Publications by authors named "Irene Ng"

303 Publications

Inhibition of CMTM4 Sensitizes Cholangiocarcinoma and Hepatocellular Carcinoma to T Cell-Mediated Antitumor Immunity Through PD-L1.

Hepatol Commun 2021 Jul 21. Epub 2021 Jul 21.

Department of Pathology, The University of Hong Kong, Hong Kong.

Liver cancers consist primarily of hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC). Immune checkpoint inhibitors have emerged as promising therapeutic agents against liver cancers. Programmed cell death protein 1 (PD-1) is an immunoinhibitory receptor present on T cells that interacts with its ligand programmed death-ligand 1 (PD-L1) found on cancer cells. Blocking PD-1/PD-L1 binding improves T-cell survival, proliferation and cytotoxicity, which enhances their antitumor activity. Better understanding of the molecular mechanisms governing PD-1/PD-L1 response is essential to the development of predictive markers and therapeutic combinations that could improve the efficiency of anti-PD-1/PD-L1 treatment. Chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing 6 (CMTM6) has been recently identified as a major regulator of PD-L1. Another member in the CMTM family, CKLF-like MARVEL transmembrane domain-containing 4 (CMTM4), has been shown to compensate for the effects of CMTM6 when CMTM6 is lost. Interestingly, we found that CMTM4 is the major regulator of PD-L1 in the context of liver cancer. Up-regulated CMTM4 in patients with HCC and ICC is associated with poor patient survival, potentially due to its function in stabilizing PD-L1 expression, hence facilitating escape from T cell-mediated cytotoxicity. We confirmed the role of CMTM4 as a positive regulator of PD-L1 in multiple HCC and ICC cell lines and demonstrated that CMTM4 stabilizes PD-L1 through posttranslational mechanisms. In vivo, suppression of Cmtm4 inhibited HCC growth and increased CD8 T-cell infiltration in immunocompetent mice. Furthermore, we found that depletion of CMTM4 sensitized HCC tumor to anti-PD-L1 treatment compared with control. This suggests that CMTM4 expression level could be a predictive marker for patient response to anti-PD-L1 treatment, and CMTM4 depletion can potentially be used to enhance the clinical benefits of anti-PD-L1 immunotherapy in patients with liver cancer.
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http://dx.doi.org/10.1002/hep4.1682DOI Listing
July 2021

High levels of psychosocial distress among Australian frontline healthcare workers during the COVID-19 pandemic: a cross-sectional survey.

Gen Psychiatr 2021 6;34(5):e100577. Epub 2021 Sep 6.

College of Health and Biomedicine, Victoria University, Footscray, Victoria, Australia.

Background: The coronavirus disease 2019 (COVID-19) pandemic has had a profound and prolonged impact on healthcare services and healthcare workers.

Aims: The Australian COVID-19 Frontline Healthcare Workers Study aimed to investigate the severity and prevalence of mental health issues, as well as the social, workplace and financial disruptions experienced by Australian healthcare workers during the COVID-19 pandemic.

Methods: A nationwide, voluntary, anonymous, single timepoint, online survey was conducted between 27 August and 23 October 2020. Individuals self-identifying as frontline healthcare workers in secondary or primary care were invited to participate. Participants were recruited through health organisations, professional associations or colleges, universities, government contacts and national media. Demographics, home and work situation, health and psychological well-being data were collected.

Results: A total of 9518 survey responses were received; of the 9518 participants, 7846 (82.4%) participants reported complete data. With regard to age, 4110 (52.4%) participants were younger than 40 years; 6344 (80.9%) participants were women. Participants were nurses (n=3088, 39.4%), doctors (n=2436, 31.1%), allied health staff (n=1314, 16.7%) or in other roles (n=523, 6.7%). In addition, 1250 (15.9%) participants worked in primary care. Objectively measured mental health symptoms were common: mild to severe anxiety (n=4694, 59.8%), moderate to severe burnout (n=5458, 70.9%) and mild to severe depression (n=4495, 57.3%). Participants were highly resilient (mean (SD)=3.2 (0.66)). Predictors for worse outcomes on all scales included female gender; younger age; pre-existing psychiatric condition; experiencing relationship problems; nursing, allied health or other roles; frontline area; being worried about being blamed by colleagues and working with patients with COVID-19.

Conclusions: The COVID-19 pandemic is associated with significant mental health symptoms in frontline healthcare workers. Crisis preparedness together with policies and practices addressing psychological well-being are needed.
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http://dx.doi.org/10.1136/gpsych-2021-100577DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8423519PMC
September 2021

Coping strategies adopted by Australian frontline health workers to address psychological distress during the COVID-19 pandemic.

Gen Hosp Psychiatry 2021 Sep-Oct;72:124-130. Epub 2021 Aug 20.

School of Allied Health, Human Services and Sport, La Trobe University, Bundoora, Melbourne, Vic 3083, Australia; Division of Critical Care and Investigative Services, Royal Melbourne Hospital, Grattan Street, Parkville, Vic 3050, Australia.

Objectives: The Australian COVID-19 Frontline Healthcare Workers Study investigated coping strategies and help-seeking behaviours, and their relationship to mental health symptoms experienced by Australian healthcare workers (HCWs) during the COVID-19 pandemic.

Methods: Australian HCWs were invited to participate a nationwide, voluntary, anonymous, single time-point, online survey between 27th August and 23rd October 2020. Complete responses on demographics, home and work situation, and measures of health and psychological wellbeing were received from 7846 participants.

Results: The most commonly reported adaptive coping strategies were maintaining exercise (44.9%) and social connections (31.7%). Over a quarter of HCWs (26.3%) reported increased alcohol use which was associated with a history of poor mental health and worse personal relationships. Few used psychological wellbeing apps or sought professional help; those who did were more likely to be suffering from moderate to severe symptoms of mental illness. People living in Victoria, in regional areas, and those with children at home were significantly less likely to report adaptive coping strategies.

Conclusions: Personal, social, and workplace predictors of coping strategies and help-seeking behaviour during the pandemic were identified. Use of maladaptive coping strategies and low rates of professional help-seeking indicate an urgent need to understand the effectiveness of, and the barriers and enablers of accessing, different coping strategies.
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http://dx.doi.org/10.1016/j.genhosppsych.2021.08.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8437691PMC
August 2021

TPI1-reduced extracellular vesicles mediated by Rab20 downregulation promotes aerobic glycolysis to drive hepatocarcinogenesis.

J Extracell Vesicles 2021 08 11;10(10):e12135. Epub 2021 Aug 11.

Department of Pathology Li Ka Shing Faculty of Medicine The University of Hong Kong Hong Kong China.

Rab GTPases are major mediators that ensure the proper spatiotemporal regulation of intracellular trafficking. Functional impairment and altered expression of Rab proteins have been revealed in various human cancers. There is an emerging evidence about the role of Rab proteins in the biogenesis of extracellular vesicles (EVs). In hepatocellular carcinoma (HCC), using RNA sequencing comparing expression profiles of adjacent non-tumorous tissues and HCC, Rab20 is identified to be the most frequently downregulated Rab member in HCC. Functionally, restoration of Rab20 in metastatic HCC cells results in the release of EVs with a diminished activity to promote cell growth, motility and metastasis. Conversely, EVs released from normal liver cells with Rab20 knockdown loses suppressive effect on HCC cell growth and motility. Proteomic profiling revealed the level of triosephosphate isomerase 1 (TPI1), a glycolytic enzyme, in EVs to be positively associated with Rab20 expression of the releasing cells. TPI1 targeted to be expressed in EVs released by Rab20 knockdown cells compromises the oncogenic activity of EVs. Besides, EVs released by TPI1 knockdown cells recapitulates the promoting effect of EVs derived from HCC cells with Rab20 underexpression. Aerobic glycolysis is beneficial to the survival and proliferation of tumour cells. Here, we observed that the enhanced cell growth and motility are driven by the enhanced aerobic glycolysis induced by EVs with reduced TPI1. The addition of glycolytic inhibitor blocks the promoting effect of EVs with reduced TPI1. Taken together, our study provides a mechanistic link among tumour cell-derived EVs and glucose metabolism in HCC with Rab20 deregulation.
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http://dx.doi.org/10.1002/jev2.12135DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8357635PMC
August 2021

"It's like the stages of grief": A Qualitative Study of the Psychological Experience of Frontline Perioperative Healthcare Staff in Responding to COVID-19.

JMIR Perioper Med 2021 Aug 2. Epub 2021 Aug 2.

Allied Health; Royal Melbourne Hospital, Parkville, AU.

Background: The rapid spread of the novel corona virus (COVID-19) has presented immeasurable challenges to healthcare workers who remain at the frontline of the pandemic. A rapidly evolving body of literature has quantitatively demonstrated significant psychological impacts of the pandemic on healthcare workers. However, little is known about the lived experience of the pandemic for frontline medical staff.

Objective: This study aimed to explore the qualitative experience of peri-operative staff from a large trauma hospital in Melbourne, Australia.

Methods: Inductive thematic analysis using a critical realist approach was used to analyse data from nine semi-structured interviews.

Results: Four key themes were identified. Hospital preparedness related to the perceived readiness of the hospital to respond to the pandemic and encompassed key subthemes around communication of policy changes, team leadership and resource availability. Perceptions of readiness contributed to the perceived psychological impacts of the pandemic, which were highly varied and ranged from anger to anxiety. A number of coping strategies were identified in response to psychological impacts which incorporated both internal and external coping mechanisms. Finally, adaptation with time reflected change and growth over time, and encompassed all other themes.

Conclusions: While frontline staff and hospitals have rapidly marshalled a response to managing the virus, relatively less consideration was seen regarding staff mental health in our study. Findings highlight the vulnerability of healthcare workers in response to the pandemic and reinforce the need for a coordinated approach to managing mental health.

Clinicaltrial:
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http://dx.doi.org/10.2196/27166DOI Listing
August 2021

Bromodomain-containing protein BRPF1 is a therapeutic target for liver cancer.

Commun Biol 2021 07 20;4(1):888. Epub 2021 Jul 20.

State Key Laboratory of Liver Research, The University of Hong Kong, Pok Fu Lam, Hong Kong.

Epigenetic deregulation plays an essential role in hepatocellular carcinoma (HCC) progression. Bromodomains are epigenetic "readers" of histone acetylation. Recently, bromodomain inhibitors have exhibited promising therapeutic potential for cancer treatment. Using transcriptome sequencing, we identified BRPF1 (bromodomain and PHD finger containing 1) as the most significantly upregulated gene among the 43 bromodomain-containing genes in human HCC. BRPF1 upregulation was significantly associated with poor patient survival. Gene ablation or pharmacological inactivation of BRPF1 significantly attenuated HCC cell growth in vitro and in vivo. BRPF1 was involved in cell cycle progression, senescence and cancer stemness. Transcriptome sequencing revealed that BRPF1 is a master regulator controlling the expression of multiple key oncogenes, including E2F2 and EZH2. We demonstrated that BRPF1 activated E2F2 and EZH2 expression by facilitating promoter H3K14 acetylation through MOZ/MORF complex. In conclusion, BRPF1 is frequently upregulated in human HCCs. Targeting BRPF1 may be an approach for HCC treatment.
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http://dx.doi.org/10.1038/s42003-021-02405-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8292510PMC
July 2021

Impact on quantitative fit-test results after application of prophylactic hydrocolloid dressing under N95 respirators.

Infect Control Hosp Epidemiol 2021 Jun 24:1-4. Epub 2021 Jun 24.

Department of Anaesthesia and Pain Management, Royal Melbourne Hospital, Parkville, Australia.

Objective: Discomfort and device-related pressure injury (DRPI) caused by N95 filtering facepiece respirators (FFRs) are common. The use of prophylactic hydrocolloid dressings is one of the strategies that may improve comfort and reduce DRPI. In this study, we investigated the impact of these dressings on N95 respirator fit.

Methods: We performed a repeat quantitative fit testing through the Respiratory Protection Program on 134 healthcare workers (HCWs), who applied hydrocolloid dressings on the bridge of their nose under the N95 FFRs that they passed the initial fit test with, but reported discomfort with the FFR.

Results: With the hydrocolloid dressings in place, the fit-test pass rate for the semirigid cup style (3M 1860) was 94% (108 of 115); for the the vertical flat-fold style (BYD), the pass rate was 85% (44 of 52); for the duckbill style (BSN medical ProShield and Halyard Fluidshield), the pass rate was 81% (87 of 108); and for the 3-panel flat-fold style (3M Aura) N95 FFRs, the pass rate was 100% (3 of 3). There was a statistically significant reduction in the overall fit factors for both the vertical flat-fold and duckbill type N95 respirators after the application of hydrocolloid dressings.

Conclusions: Hydrocolloid dressings are likely to disturb the mask seal for nonrigid-style N95 FFRs, particularly the vertical flat-fold style and the duckbill style N95 FFRs. Given the risk of mask seal disturbance of N95 respirators as shown in this study, we advocate that any HCW requiring the use of prophylactic dressings should undergo repeat quantitative fit testing with the dressing in place prior to using the dressing and mask in combination.
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http://dx.doi.org/10.1017/ice.2021.293DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8314196PMC
June 2021

Single-cell RNA sequencing shows the immunosuppressive landscape and tumor heterogeneity of HBV-associated hepatocellular carcinoma.

Nat Commun 2021 06 17;12(1):3684. Epub 2021 Jun 17.

Department of Pathology, The University of Hong Kong, Hong Kong, China.

Interaction between tumor cells and immune cells in the tumor microenvironment is important in cancer development. Immune cells interact with the tumor cells to shape this process. Here, we use single-cell RNA sequencing analysis to delineate the immune landscape and tumor heterogeneity in a cohort of patients with HBV-associated human hepatocellular carcinoma (HCC). We found that tumor-associated macrophages suppress tumor T cell infiltration and TIGIT-NECTIN2 interaction regulates the immunosuppressive environment. The cell state transition of immune cells towards a more immunosuppressive and exhaustive status exemplifies the overall cancer-promoting immunocellular landscape. Furthermore, the heterogeneity of global molecular profiles reveals co-existence of intra-tumoral and inter-tumoral heterogeneity, but is more apparent in the latter. This analysis of the immunosuppressive landscape and intercellular interactions provides mechanistic information for the design of efficacious immune-oncology treatments in hepatocellular carcinoma.
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http://dx.doi.org/10.1038/s41467-021-24010-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8211687PMC
June 2021

A single oral glucose load decreases arterial plasma [K ] during exercise and recovery.

Physiol Rep 2021 Jun;9(11):e14889

Institute for Health and Sport, Victoria University, Melbourne, VIC, Australia.

Aim: We investigated whether acute carbohydrate ingestion reduced arterial potassium concentration ([K ]) during and after intense exercise and delayed fatigue.

Methods: In a randomized, double-blind crossover design, eight males ingested 300 ml water containing 75 g glucose (CHO) or placebo (CON); rested for 60 min, then performed high-intensity intermittent cycling (HIIC) at 130% , comprising three 45-s exercise bouts (EB), then a fourth EB until fatigue. Radial arterial (a) and antecubital venous (v) blood was sampled at rest, before, during and after HIIC and analyzed for plasma ions and metabolites, with forearm arteriovenous differences (a-v diff) calculated to assess inactive forearm muscle effects.

Results: Glucose ingestion elevated [glucose] and [insulin] above CON (p = .001), being, respectively, ~2- and ~5-fold higher during CHO at 60 min after ingestion (p = .001). Plasma [K ] rose during and declined following each exercise bout in HIIC (p = .001), falling below baseline at 5 min post-exercise (p = .007). Both [K ] and [K ] were lower during CHO (p = .036, p = .001, respectively, treatment main effect). The [K ] across the forearm widened during exercise (p = .001), returned to baseline during recovery, and was greater in CHO than CON during EB1, EB2 (p = .001) and EB3 (p = .005). Time to fatigue did not differ between trials.

Conclusion: Acute oral glucose ingestion, as used in a glucose tolerance test, induced a small, systemic K -lowering effect before, during, and after HIIC, that was detectable in both arterial and venous plasma. This likely reflects insulin-mediated, increased Na ,K -ATPase induced K uptake into non-contracting muscles. However, glucose ingestion did not delay fatigue.
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http://dx.doi.org/10.14814/phy2.14889DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8191174PMC
June 2021

Suppression of ACADM-Mediated Fatty Acid Oxidation Promotes Hepatocellular Carcinoma via Aberrant CAV1/SREBP1 Signaling.

Cancer Res 2021 Jul 11;81(13):3679-3692. Epub 2021 May 11.

Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China.

Lipid accumulation exacerbates tumor development, as it fuels the proliferative growth of cancer cells. The role of medium-chain acyl-CoA dehydrogenase (ACADM), an enzyme that catalyzes the first step of mitochondrial fatty acid oxidation, in tumor biology remains elusive. Therefore, investigating its mode of dysregulation can shed light on metabolic dependencies in cancer development. In hepatocellular carcinoma (HCC), ACADM was significantly underexpressed, correlating with several aggressive clinicopathologic features observed in patients. Functionally, suppression of ACADM promoted HCC cell motility with elevated triglyceride, phospholipid, and cellular lipid droplet levels, indicating the tumor suppressive ability of ACADM in HCC. Sterol regulatory element-binding protein-1 (SREBP1) was identified as a negative transcriptional regulator of ACADM. Subsequently, high levels of caveolin-1 (CAV1) were observed to inhibit fatty acid oxidation, which revealed its role in regulating lipid metabolism. CAV1 expression negatively correlated with ACADM and its upregulation enhanced nuclear accumulation of SREBP1, resulting in suppressed ACADM activity and contributing to increased HCC cell aggressiveness. Administration of an SREBP1 inhibitor in combination with sorafenib elicited a synergistic antitumor effect and significantly reduced HCC tumor growth . These findings indicate that deregulation of fatty acid oxidation mediated by the CAV1/SREBP1/ACADM axis results in HCC progression, which implicates targeting fatty acid metabolism to improve HCC treatment. SIGNIFICANCE: This study identifies tumor suppressive effects of ACADM in hepatocellular carcinoma and suggests promotion of β-oxidation to diminish fatty acid availability to cancer cells could be used as a therapeutic strategy.
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http://dx.doi.org/10.1158/0008-5472.CAN-20-3944DOI Listing
July 2021

EPHB2 Activates β-Catenin to Enhance Cancer Stem Cell Properties and Drive Sorafenib Resistance in Hepatocellular Carcinoma.

Cancer Res 2021 Jun 26;81(12):3229-3240. Epub 2021 Apr 26.

Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, P.R. China.

The survival benefit derived from sorafenib treatment for patients with hepatocellular carcinoma (HCC) is modest due to acquired resistance. Targeting cancer stem cells (CSC) is a possible way to reverse drug resistance, however, inhibitors that specifically target liver CSCs are limited. In this study, we established two sorafenib-resistant, patient-derived tumor xenografts (PDX) that mimicked development of acquired resistance to sorafenib in patients with HCC. RNA-sequencing analysis of sorafenib-resistant PDXs and their corresponding mock controls identified EPH receptor B2 (EPHB2) as the most significantly upregulated kinase. EPHB2 expression increased stepwise from normal liver tissue to fibrotic liver tissue to HCC tissue and correlated with poor prognosis. Endogenous EPHB2 knockout showed attenuation of tumor development in mice. EPHB2 regulated the traits of liver CSCs; similarly, sorted EPHB2High HCC cells were endowed with enhanced CSC properties when compared with their EPHB2-Low counterparts. Mechanistically, EPHB2 regulated cancer stemness and drug resistance by driving the SRC/AKT/GSK3β/β-catenin signaling cascade, and EPHB2 expression was regulated by TCF1 via promoter activation, forming a positive Wnt/β-catenin feedback loop. Intravenous administration of rAAV-8-shEPHB2 suppressed HCC tumor growth and significantly sensitized HCC cells to sorafenib in an NRAS/AKT-driven HCC immunocompetent mouse model. Targeting a positive feedback loop involving the EPHB2/β-catenin axis may be a possible therapeutic strategy to combat acquired drug resistance in HCC. SIGNIFICANCE: This study identifies a EPHB2/β-catenin/TCF1 positive feedback loop that augments cancer stemness and sorafenib resistance in HCC, revealing a targetable axis to combat acquired drug resistance in HCC. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/12/3229/F1.large.jpg.
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http://dx.doi.org/10.1158/0008-5472.CAN-21-0184DOI Listing
June 2021

A randomised crossover study to compare the user seal check and quantitative fit test between two types of duckbill N95 particulate respirator masks: The Halyard Fluidshield® N95 and the BSN Medical ProShield® N-95 particulate respirator masks.

Anaesth Intensive Care 2021 Mar 4;49(2):112-118. Epub 2021 Apr 4.

Department of Anaesthesia and Pain Management, Royal Melbourne Hospital, Parkville, Australia.

N95 particulate respirator masks are currently recommended for all healthcare workers who care for patients with suspected or confirmed coronavirus disease (COVID-19) when performing aerosol-generating procedures. The protection provided by N95 particulate respirator masks is dependent on the filter's efficiency and seal quality. In this prospective randomised crossover study, we conducted the user seal check and the quantitative fit test on two readily available duckbill models of N95 masks, the Halyard Fluidshield® N95 (Halyard, Alpharetta, GA, USA) and the BSN Medical ProShield® N-95 (BSN Medical, Mount Waverley, Victoria) particulate respirator masks. We recruited a total of 96 anaesthetic staff, of whom 26% were of South-East Asian ethnicity. We found that both types of masks provided reasonably high fit test pass rates among our participants and there was no significant difference between the two brands (77% for the Fluidshield and 65% for the ProShield,  = 0.916). Ninety-two percent of the participants could find at least one well-fitted mask among these two types of masks. We also demonstrated that the user seal check had low accuracy and low concordance (kappa coefficient of 0.16 for the Fluidshield and 0.08 for the ProShield) when compared to the quantitative fit test, and hence was not a reliable method to test seal quality.
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http://dx.doi.org/10.1177/0310057X20974022DOI Listing
March 2021

Rare case of torsion of giant ovarian mass post-colonoscopy.

J Surg Case Rep 2021 Mar 29;2021(3):rjab070. Epub 2021 Mar 29.

Department of Sarcoma, Peritoneal and Rare Tumours (SPRinT), Division of Surgery and Surgical Oncology, National Cancer Centre Singapore, Singapore.

We present an unprecedented case of torsion of a large ovarian cyst following colonoscopy. A 43-year-old female was found to have a 20 × 13 × 19 cm pelviabdominal mass possibly arising from the right ovary. Endoscopic evaluation was performed prior to planned resection of the ovarian mass. The patient experienced progressive lower abdominal pain after the procedure with a computed topography finding of torsion. She underwent exploratory laparotomy, right salpingo-oophorectomy with intra-operative frozen section and omentectomy. Final histology revealed features of benign serous cystadenoma with extensive haemorrhagic infarction in keeping with torsion. To our knowledge, this is the first reported case of torsion of a large ovarian cyst after colonoscopy. We propose a postulated mechanism of this patient's ovarian torsion and urge clinicians to be cognizant of acute ovarian torsion as a cause of severe abdominal pain following endoscopy.
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http://dx.doi.org/10.1093/jscr/rjab070DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8007174PMC
March 2021

RALYL increases hepatocellular carcinoma stemness by sustaining the mRNA stability of TGF-β2.

Nat Commun 2021 03 9;12(1):1518. Epub 2021 Mar 9.

Department of Clinical Oncology, The University of Hong Kong, Hong Kong, China.

Growing evidences suggest that cancer stem cells exhibit many molecular characteristics and phenotypes similar to their ancestral progenitor cells. In the present study, human embryonic stem cells are induced to differentiate into hepatocytes along hepatic lineages to mimic liver development in vitro. A liver progenitor specific gene, RALY RNA binding protein like (RALYL), is identified. RALYL expression is associated with poor prognosis, poor differentiation, and metastasis in clinical HCC patients. Functional studies reveal that RALYL could promote HCC tumorigenicity, self-renewal, chemoresistance, and metastasis. Moreover, molecular mechanism studies show that RALYL could upregulate TGF-β2 mRNA stability by decreasing N6-methyladenosine (mA) modification. TGF-β signaling and the subsequent PI3K/AKT and STAT3 pathways, upregulated by RALYL, contribute to the enhancement of HCC stemness. Collectively, RALYL is a liver progenitor specific gene and regulates HCC stemness by sustaining TGF-β2 mRNA stability. These findings may inspire precise therapeutic strategies for HCC.
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http://dx.doi.org/10.1038/s41467-021-21828-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7943813PMC
March 2021

Cellular heterogeneity and plasticity in liver cancer.

Semin Cancer Biol 2021 Feb 26. Epub 2021 Feb 26.

Department of Pathology, The University of Hong Kong, Hong Kong; State Key Laboratory of Liver Research, The University of Hong Kong, Hong Kong. Electronic address:

Hepatocarcinogenesis involves complex genetic and cellular dysregulations which drive the formation of hepatocellular carcinoma (HCC), the predominant form of primary liver cancer, with extensive heterogeneity. In contrast to the broad spectrum of molecularly driven therapies available for defined patient groups in certain cancer types, unfortunately the treatment options for HCC are highly limited. The lack of representative molecular and cellular signatures in the heterogeneous HCC tumors that can effectively guide the choice of the most appropriate treatment among the patients unavoidably limits the treatment outcome. Advancement and wide availability of the next-generation sequencing technologies have empowered us to examine and capture not only the detailed genetic alterations of the HCC cells but also the precise composition of different cell types within the tumor microenvironment and their interactions with the HCC cells at an unprecedented level. The information generated has provided new insight and better defined the inter-patient intertumoral heterogeneity, intra-patient intratumoral heterogeneity as well as the plasticity of HCC cells. These collectively provide a robust scientific basis in guiding the development and use of targeted therapy and immunotherapy. To complement, liquid biopsy coupled with high-sensitivity sequencing could potentially be adopted as a more practical and safer approach to detect and reflect the tumor heterogeneity in HCC patients in guiding the choice of treatment and monitoring disease progression.
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http://dx.doi.org/10.1016/j.semcancer.2021.02.015DOI Listing
February 2021

Adaptive and Constitutive Activations of Malic Enzymes Confer Liver Cancer Multilayered Protection Against Reactive Oxygen Species.

Hepatology 2021 Aug;74(2):776-796

Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong.

Background And Aims: HCC undergoes active metabolic reprogramming. Reactive oxygen species (ROS) are excessively generated in cancer cells and are neutralized by NADPH. Malic enzymes (MEs) are the less studied NADPH producers in cancer.

Approach And Results: We found that ME1, but not ME3, was regulated by the typical oxidative stress response pathway mediated by kelch-like ECH associated protein 1/nuclear factor erythroid 2-related factor (NRF2). Surprisingly, ME3 was constitutively induced by superenhancers. Disruption of any ME regulatory pathways decelerated HCC progression and sensitized HCC to sorafenib. Therapeutically, simultaneous blockade of NRF2 and a superenhancer complex completely impeded HCC growth. We show that superenhancers allow cancer cells to counteract the intrinsically high level of ROS through constitutively activating ME3 expression. When HCC cells encounter further episodes of ROS insult, NRF2 allows cancer cells to adapt by transcriptionally activating ME1.

Conclusions: Our study reveals the complementary regulatory mechanisms which control MEs and provide cancer cells multiple layers of defense against oxidative stress. Targeting both regulatory mechanisms represents a potential therapeutic approach for HCC treatment.
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http://dx.doi.org/10.1002/hep.31761DOI Listing
August 2021

The interplay of UBE2T and Mule in regulating Wnt/β-catenin activation to promote hepatocellular carcinoma progression.

Cell Death Dis 2021 02 1;12(2):148. Epub 2021 Feb 1.

Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, Hong Kong.

Emerging evidence indicates the role of cancer stem cells (CSCs) in tumor relapse and therapeutic resistance in patients with hepatocellular carcinoma (HCC). To identify novel targets against liver CSCs, an integrative analysis of publicly available datasets involving HCC clinical and stemness-related data was employed to select genes that play crucial roles in HCC via regulation of liver CSCs. We revealed an enrichment of an interstrand cross-link repair pathway, in which ubiquitin-conjugating enzyme E2 T (UBE2T) was the most significantly upregulated. Consistently, our data showed that UBE2T was upregulated in enriched liver CSC populations. Clinically, UBE2T overexpression in HCC was further confirmed at mRNA and protein levels and was correlated with advanced tumor stage and poor patient survival. UBE2T was found to be critically involved in the regulation of liver CSCs, as evidenced by increases in self-renewal, drug resistance, tumorigenicity, and metastasis abilities. Mule, an E3 ubiquitin ligase, was identified to be the direct protein binding partner of UBE2T. Rather than the canonical role of acting as a mediator to transfer ubiquitin to E3 ligases, UBE2T is surprisingly able to physically bind and regulate the protein expression of Mule via ubiquitination. Mule was found to directly degrade β-catenin protein, and UBE2T was found to mediate liver CSC functions through direct regulation of Mule-mediated β-catenin degradation; this effect was abolished when the E2 activity of UBE2T was impaired. In conclusion, we revealed a novel UBE2T/Mule/β-catenin signaling cascade that is involved in the regulation of liver CSCs, which provides an attractive potential therapeutic target for HCC.
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http://dx.doi.org/10.1038/s41419-021-03403-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7862307PMC
February 2021

Genome-wide CRISPR-Cas9 knockout library screening identified PTPMT1 in cardiolipin synthesis is crucial to survival in hypoxia in liver cancer.

Cell Rep 2021 01;34(4):108676

Department of Pathology, The University of Hong Kong, Hong Kong; State Key Laboratory of Liver Research, The University of Hong Kong, Hong Kong. Electronic address:

Hypoxia, low oxygen (O), is a key feature of all solid cancers, including hepatocellular carcinoma (HCC). Genome-wide CRISPR-Cas9 knockout library screening is used to identify reliable therapeutic targets responsible for hypoxic survival in HCC. We find that protein-tyrosine phosphatase mitochondrial 1 (PTPMT1), an important enzyme for cardiolipin (CL) synthesis, is the most significant gene and ranks just after hypoxia-inducible factor (HIF)-1α and HIF-1β as crucial to hypoxic survival. CL constitutes the mitochondrial membrane and ensures the proper assembly of electron transport chain (ETC) complexes for efficient electron transfer in respiration. ETC becomes highly unstable during hypoxia. Knockout of PTPMT1 stops the maturation of CL and impairs the assembly of ETC complexes, leading to further electron leakage and ROS accumulation at ETC in hypoxia. Excitingly, HCC cells, especially under hypoxic conditions, show great sensitivity toward PTPMT1 inhibitor alexidine dihydrochloride (AD). This study unravels the protective roles of PTPMT1 in hypoxic survival and cancer development.
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http://dx.doi.org/10.1016/j.celrep.2020.108676DOI Listing
January 2021

Apobec1 complementation factor overexpression promotes hepatic steatosis, fibrosis, and hepatocellular cancer.

J Clin Invest 2021 01;131(1)

Division of Gastroenterology, Washington University School of Medicine, St. Louis, Missouri, USA.

The RNA-binding protein Apobec1 complementation factor (A1CF) regulates posttranscriptional ApoB mRNA editing, but the range of RNA targets and the long-term effect of altered A1CF expression on liver function are unknown. Here we studied hepatocyte-specific A1cf-transgenic (A1cf+/Tg), A1cf+/Tg Apobec1-/-, and A1cf-/- mice fed chow or high-fat/high-fructose diets using RNA-Seq, RNA CLIP-Seq, and tissue microarrays from human hepatocellular cancer (HCC). A1cf+/Tg mice exhibited increased hepatic proliferation and steatosis, with increased lipogenic gene expression (Mogat1, Mogat2, Cidea, Cd36) associated with shifts in polysomal RNA distribution. Aged A1cf+/Tg mice developed spontaneous fibrosis, dysplasia, and HCC, and this development was accelerated on a high-fat/high-fructose diet and was independent of Apobec1. RNA-Seq revealed increased expression of mRNAs involved in oxidative stress (Gstm3, Gpx3, Cbr3), inflammatory response (Il19, Cxcl14, Tnfα, Ly6c), extracellular matrix organization (Mmp2, Col1a1, Col4a1), and proliferation (Kif20a, Mcm2, Mcm4, Mcm6), and a subset of mRNAs (including Sox4, Sox9, Cdh1) were identified in RNA CLIP-Seq. Increased A1CF expression in human HCC correlated with advanced fibrosis and with reduced survival in a subset with nonalcoholic fatty liver disease. In conclusion, we show that hepatic A1CF overexpression selectively alters polysomal distribution and mRNA expression, promoting lipogenic, proliferative, and inflammatory pathways leading to HCC.
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http://dx.doi.org/10.1172/JCI138699DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7773377PMC
January 2021

Exosomes derived from Vδ2-T cells control Epstein-Barr virus-associated tumors and induce T cell antitumor immunity.

Sci Transl Med 2020 09;12(563)

Department of Paediatrics and Adolescent Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong 999077, China.

Treatment of life-threatening Epstein-Barr virus (EBV)-associated tumors remains a great challenge, especially for patients with relapsed or refractory disease. Here, we found that exosomes derived from phosphoantigen-expanded Vδ2-T cells (Vδ2-T-Exos) contained death-inducing ligands (FasL and TRAIL), an activating receptor for natural killer (NK) cells (NKG2D), immunostimulatory ligands (CD80 and CD86), and antigen-presenting molecules (MHC class I and II). Vδ2-T-Exos targeted and efficiently killed EBV-associated tumor cells through FasL and TRAIL pathways and promoted EBV antigen-specific CD4 and CD8 T cell expansion. Administration of Vδ2-T-Exos effectively controlled EBV-associated tumors in Rag2γc and humanized mice. Because expanding Vδ2-T cells and preparing autologous Vδ2-T-Exos from cancer patients ex vivo in large scale is challenging, we explored the antitumor activity of allogeneic Vδ2-T-Exos in humanized mouse cancer models. Here, we found that allogeneic Vδ2-T-Exos had more effective antitumor activity than autologous Vδ2-T-Exos in humanized mice; the allogeneic Vδ2-T-Exos increased the infiltration of T cells into tumor tissues and induced more robust CD4 and CD8 T cell-mediated antitumor immunity. Compared with exosomes derived from NK cells (NK-Exos) with direct cytotoxic antitumor activity or dendritic cells (DC-Exos) that induced T cell antitumor responses, Vδ2-T-Exos directly killed tumor cells and induced T cell-mediated antitumor response, thus resulting in more effective control of EBV-associated tumors. This study provided proof of concept for the strategy of using Vδ2-T-Exos, especially allogeneic Vδ2-T-Exos, to treat EBV-associated tumors.
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http://dx.doi.org/10.1126/scitranslmed.aaz3426DOI Listing
September 2020

RSK2-inactivating mutations potentiate MAPK signaling and support cholesterol metabolism in hepatocellular carcinoma.

J Hepatol 2021 02 9;74(2):360-371. Epub 2020 Sep 9.

Department of Pathology, The University of Hong Kong, Hong Kong; State Key Laboratory of Liver Research, The University of Hong Kong, Hong Kong. Electronic address:

Background & Aims: Mutational profiling of patient tumors has suggested that hepatocellular carcinoma (HCC) development is mainly driven by loss-of-function mutations in tumor suppressor genes. p90 ribosomal S6 kinase 2 (RSK2) functions as a direct downstream kinase of ERK1/2 and elevated RSK2 expression has been reported to support oncogenic functions in some cancers. We investigated if RSK2 was also dysregulated by inactivating mutations in cancers including HCC.

Methods: We performed exome sequencing and targeted DNA sequencing on HBV-associated HCCs to examine recurrent RSK2 mutations. The functional significance and mechanistic consequences of RSK2 mutations were examined in natural RSK2-null HCC cells, and RSK2-knockout HCC cells. The potential downstream pathways underlying RSK2 mutations were investigated by RNA sequencing, qRT-PCR and mass spectrometry.

Results: We detected recurrent somatic RSK2 mutations at a rate of 6.3% in our HCC cohorts and revealed that, among many cancer types, HCC was the cancer most commonly harboring RSK2 mutations. The RSK2 mutations were inactivating and associated with a more aggressive tumor phenotype. We found that, functionally, restoring RSK2 expression in natural RSK2-null HBV-positive Hep3B cells suppressed proliferation and migration in vitro and tumorigenicity in vivo. Mechanistically, RSK2-inactivating mutations attenuated a SOS1/2-dependent negative feedback loop, leading to the activation of MAPK signaling. Of note, this RSK2 mutation-mediated MAPK upregulation rendered HCC cells more sensitive to sorafenib, a first-line multi-kinase inhibitor for advanced HCC. Furthermore, such activation of MAPK signaling enhanced cholesterol biosynthesis-related gene expression in HCC cells.

Conclusions: Our findings reveal the mechanistic and functional significance of RSK2-inactivating mutations in HCC. These inactivating mutations may serve as an alternative route to activate MAPK signaling and cholesterol metabolism in HCC.

Lay Summary: In this study, we identified and functionally characterized RSK2-inactivating mutations in human hepatocellular carcinoma and demonstrated their association with aggressive tumor behavior. Mutations in RSK2 drive signaling pathways with known oncogenic potential, leading to enhanced cholesterol biosynthesis and potentially sensitizing tumors to sorafenib treatment.
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http://dx.doi.org/10.1016/j.jhep.2020.08.036DOI Listing
February 2021

Corrigendum to "NRF2/SHH signaling cascade promotes tumor-initiating cell lineage and drug resistance in hepatocellular carcinoma" [Canc. Lett. 476 (2020) 48-56].

Cancer Lett 2021 Feb 17;499. Epub 2020 Jun 17.

Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong; State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong. Electronic address:

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http://dx.doi.org/10.1016/j.canlet.2020.06.007DOI Listing
February 2021

Anti-tumour effects of PIM kinase inhibition on progression and chemoresistance of hepatocellular carcinoma.

J Pathol 2020 09 31;252(1):65-76. Epub 2020 Jul 31.

Department of Pathology, The University of Hong Kong, Hong Kong SAR, PR China.

Hepatocellular carcinoma (HCC) is a biologically aggressive cancer. Targeted therapy is in need to tackle challenges in the treatment perspective. A growing body of evidence suggests a promising role of pharmacological inhibition of PIM (proviral integration site for Moloney murine leukaemia virus) kinase in some human haematological and solid cancers. Yet to date, the potential application of PIM inhibitors in HCC is still largely unexplored. In the present study we investigated the pre-clinical efficacy of PIM inhibition as a therapeutic approach in HCC. Effects of PIM inhibitors on cell proliferation, migration, invasion, chemosensitivity, and self-renewal were examined in vitro. The effects of PIM inhibitors on tumour growth and chemoresistance in vivo were studied using xenograft mouse models. Potential downstream molecular mechanisms were elucidated by RNA sequencing (RNA-seq) of tumour tissues harvested from animal models. Our findings demonstrate that PIM inhibitors SGI-1776 and PIM447 reduced HCC proliferation, metastatic potential, and self-renewal in vitro. Results from in vivo experiments supported the role of PIM inhibition in suppressing of tumour growth and increasing chemosensitivity of HCC toward cisplatin and doxorubicin, the two commonly used chemotherapeutic agents in trans-arterial chemoembolisation (TACE) for HCC. RNA-seq analysis revealed downregulation of the MAPK/ERK pathway upon PIM inhibition in HCC cells. In addition, LOXL2 and ICAM1 were identified as potential downstream effectors. Taken together, PIM inhibitors demonstrated remarkable anti-tumourigenic effects in HCC in vitro and in vivo. PIM kinase inhibition is a potential approach to be exploited in formulating adjuvant therapy for HCC patients of different disease stages. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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http://dx.doi.org/10.1002/path.5492DOI Listing
September 2020

Knowledge-based analyses reveal new candidate genes associated with risk of hepatitis B virus related hepatocellular carcinoma.

BMC Cancer 2020 May 11;20(1):403. Epub 2020 May 11.

Department of Psychiatry, the University of Hong Kong, Pokfulam, Hong Kong.

Background: Recent genome-wide association studies (GWASs) have suggested several susceptibility loci of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) by statistical analysis at individual single-nucleotide polymorphisms (SNPs). However, these loci only explain a small fraction of HBV-related HCC heritability. In the present study, we aimed to identify additional susceptibility loci of HBV-related HCC using advanced knowledge-based analysis.

Methods: We performed knowledge-based analysis (including gene- and gene-set-based association tests) on variant-level association p-values from two existing GWASs of HBV-related HCC. Five different types of gene-sets were collected for the association analysis. A number of SNPs within the gene prioritized by the knowledge-based association tests were selected to replicate genetic associations in an independent sample of 965 cases and 923 controls.

Results: The gene-based association analysis detected four genes significantly or suggestively associated with HBV-related HCC risk: SLC39A8, GOLGA8M, SMIM31, and WHAMMP2. The gene-set-based association analysis prioritized two promising gene sets for HCC, cell cycle G1/S transition and NOTCH1 intracellular domain regulates transcription. Within the gene sets, three promising candidate genes (CDC45, NCOR1 and KAT2A) were further prioritized for HCC. Among genes of liver-specific expression, multiple genes previously implicated in HCC were also highlighted. However, probably due to small sample size, none of the genes prioritized by the knowledge-based association analyses were successfully replicated by variant-level association test in the independent sample.

Conclusions: This comprehensive knowledge-based association mining study suggested several promising genes and gene-sets associated with HBV-related HCC risks, which would facilitate follow-up functional studies on the pathogenic mechanism of HCC.
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http://dx.doi.org/10.1186/s12885-020-06842-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7216662PMC
May 2020

Hepatocellular Carcinoma Cells Up-regulate PVRL1, Stabilizing PVR and Inhibiting the Cytotoxic T-Cell Response via TIGIT to Mediate Tumor Resistance to PD1 Inhibitors in Mice.

Gastroenterology 2020 08 8;159(2):609-623. Epub 2020 Apr 8.

Department of Pathology, The University of Hong Kong, Hong Kong; State Key Laboratory of Liver Research, The University of Hong Kong, Hong Kong. Electronic address:

Background & Aims: Immune checkpoint inhibitors are effective in the treatment of some hepatocellular carcinomas (HCCs), but these tumors do not always respond to inhibitors of programmed cell death 1 (PDCD1, also called PD1). We investigated mechanisms of resistance of liver tumors in mice to infiltrating T cells.

Methods: Mice were given hydrodynamic tail vein injections of clustered regularly interspaced short palindromic repeats-Cas9 (CRISPR-Cas9) and transposon vectors to disrupt Trp53 and overexpress C-Myc (Trp53/C-Myc mice). Pvrl1 and Pvrl3 were knocked down in Hepa1-6 cells by using short hairpin RNAs. Hepa1-6 cells were injected into livers of C57BL/6 mice; some mice were given intraperitoneal injections of antibodies against PD1, T-cell immunoreceptor with Ig and ITIM domains (TIGIT), or CD8 before the cancer cells were injected. Liver tissues were collected from mice and analyzed by histology, immunohistochemistry, and quantitative real-time polymerase chain reaction; tumors were analyzed by mass cytometry using markers to detect T cells and other lymphocytes. We obtained HCC and nontumorous liver tissues and clinical data from patients who underwent surgery in Hong Kong and analyzed the tissues by immunohistochemistry.

Results: Trp53/C-Myc mice developed liver tumors in 3-5 weeks; injections of anti-PD1 did not slow tumor development. Tumors from mice given anti-PD1 had larger numbers of memory CD8 T cells (CD44CD62LKLRG1) and T cells that expressed PD1, lymphocyte activating 3 (LAG3), and TIGIT compared with mice not given the antibody. HCC tissues from patients had higher levels of PVRL1 messenger RNA and protein than nontumorous tissues. Increased PVRL1 was associated with shorter times of disease-free survival. Knockdown of Pvrl1 in Hepa1-6 cells caused them to form smaller tumors in mice, infiltrated by higher numbers of CD8 T cells that expressed the inhibitory protein TIGIT; these effects were not observed in mice with depletion of CD8 T cells. In Hepa1-6 cells, PVRL1 stabilized cell surface PVR, which interacted with TIGIT on CD8 T cells; knockdown of Pvrl1 reduced cell-surface levels of PVR but not levels of Pvr messenger RNA. In Trp53/C-Myc mice and mice with tumors grown from Hepa1-6 cells, injection of the combination of anti-PD1 and anti-TIGIT significantly reduced tumor growth, increased the ratio of cytotoxic to regulatory T cells in tumors, and prolonged survival.

Conclusions: PVRL1, which is up-regulated by HCC cells, stabilizes cell surface PVR, which interacts with TIGIT, an inhibitory molecule on CD8 effector memory T cells. This suppresses the ant-tumor immune response. Inhibitors of PVRL1/TIGIT, along with anti-PD1 might be developed for treatment of HCC.
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http://dx.doi.org/10.1053/j.gastro.2020.03.074DOI Listing
August 2020

Cancer stemness in hepatocellular carcinoma: mechanisms and translational potential.

Br J Cancer 2020 05 31;122(10):1428-1440. Epub 2020 Mar 31.

Department of Pathology, The University of Hong Kong, Hong Kong, Hong Kong.

Cancer stemness, referring to the stem-cell-like phenotype of cancer cells, has been recognised to play important roles in different aspects of hepatocarcinogenesis. A number of well-established cell-surface markers already exist for liver cancer stem cells, with potential new markers of liver cancer stem cells being identified. Both genetic and epigenetic factors that affect various signalling pathways are known to contribute to cancer stemness. In addition, the tumour microenvironment-both physical and cellular-is known to play an important role in regulating cancer stemness, and the potential interaction between cancer stem cells and their microenvironment has provided insight into the regulation of the tumour-initiating ability as well as the cellular plasticity of liver CSCs. Potential specific therapeutic targeting of liver cancer stemness is also discussed. With increased knowledge, effective druggable targets might be identified, with the aim of improving treatment outcome by reducing chemoresistance.
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http://dx.doi.org/10.1038/s41416-020-0823-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7217836PMC
May 2020

Nuclear DLC1 exerts oncogenic function through association with FOXK1 for cooperative activation of MMP9 expression in melanoma.

Oncogene 2020 05 25;39(20):4061-4076. Epub 2020 Mar 25.

Shenzhen Institute of Research and Innovation (HKU-SIRI), The University of Hong Kong, Shenzhen, China.

A Rho GTPase-activating protein (RhoGAP), deleted in liver cancer 1 (DLC1), is known to function as a tumor suppressor in various cancer types; however, whether DLC1 is a tumor-suppressor gene or an oncogene in melanoma remains to be clarified. Here we revealed that high DLC1 expression was detected in most of the melanoma tissues where it was localized in both the nuclei and the cytoplasm. Functional studies unveiled that DLC1 was both required and sufficient for melanoma growth and metastasis. These tumorigenic events were mediated by nuclear-localized DLC1 in a RhoGAP-independent manner. Mechanistically, mass spectrometry analysis identified a DLC1-associated protein, FOXK1 transcription factor, which mediated oncogenic events in melanoma by translocating and retaining DLC1 into the nucleus. RNA-sequencing profiling studies further revealed MMP9 as a direct target of FOXK1 through DLC1-regulated promoter occupancy for cooperative activation of MMP9 expression to promote melanoma invasion and metastasis. Concerted action of DLC1-FOXK1 in MMP9 gene regulation was further supported by their highly correlated expression in melanoma patients' samples and cell lines. Together, our results not only unravel a mechanism by which nuclear DLC1 functions as an oncogene in melanoma but also suggest an unexpected role of RhoGAP protein in transcriptional regulation.
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http://dx.doi.org/10.1038/s41388-020-1274-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7220869PMC
May 2020

Hepatitis B Virus-Telomerase Reverse Transcriptase Promoter Integration Harnesses Host ELF4, Resulting in Telomerase Reverse Transcriptase Gene Transcription in Hepatocellular Carcinoma.

Hepatology 2021 01 26;73(1):23-40. Epub 2020 Nov 26.

Department of Pathology, The University of Hong Kong, Hong Kong, China.

Background And Aims: Hepatitis B virus (HBV) integrations are common in hepatocellular carcinoma (HCC). In particular, alterations of the telomerase reverse transcriptase (TERT) gene by HBV integrations are frequent; however, the molecular mechanism and functional consequence underlying TERT HBV integration are unclear.

Approach And Results: We adopted a targeted sequencing strategy to survey HBV integrations in human HBV-associated HCCs (n = 95). HBV integration at the TERT promoter was frequent (35.8%, n = 34/95) in HCC tumors and was associated with increased TERT mRNA expression and more aggressive tumor behavior. To investigate the functional importance of various integrated HBV components, we employed different luciferase reporter constructs and found that HBV enhancer I (EnhI) was the key viral component leading to TERT activation on integration at the TERT promoter. In addition, the orientation of the HBV integration at the TERT promoter further modulated the degree of TERT transcription activation in HCC cell lines and patients' HCCs. Furthermore, we performed array-based small interfering RNA library functional screening to interrogate the potential major transcription factors that physically interacted with HBV and investigated the cis-activation of host TERT gene transcription on viral integration. We identified a molecular mechanism of TERT activation through the E74 like ETS transcription factor 4 (ELF4), which normally could drive HBV gene transcription. ELF4 bound to the chimeric HBV EnhI at the TERT promoter, resulting in telomerase activation. Stable knockdown of ELF4 significantly reduced the TERT expression and sphere-forming ability in HCC cells.

Conclusions: Our results reveal a cis-activating mechanism harnessing host ELF4 and HBV integrated at the TERT promoter and uncover how TERT HBV-integrated HCCs may achieve TERT activation in hepatocarcinogenesis.
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http://dx.doi.org/10.1002/hep.31231DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7898544PMC
January 2021

NRF2/SHH signaling cascade promotes tumor-initiating cell lineage and drug resistance in hepatocellular carcinoma.

Cancer Lett 2020 04 13;476:48-56. Epub 2020 Feb 13.

Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong; State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong. Electronic address:

Solid evidence shows that tumor-initiating cells (T-ICs) are the root of tumor relapse and drug resistance, which lead to a poor prognosis in patients with hepatocellular carcinoma (HCC). Through an in vitro liver T-IC enrichment approach, we identified nuclear factor (erythroid-derived 2)-like 2 (NRF2) as a transcription regulator that is significantly activated in enriched liver T-IC populations. In human HCCs, NRF2 was found to be overexpressed, which was associated with poor patient survival. Through a lentiviral based knockdown approach, NRF2 was found to be critical for regulating liver T-IC properties, including self-renewal, tumorigenicity, drug resistance and expression of liver T-IC markers. Furthermore, we found that ROS-induced NRF2 activation regulates sorafenib resistance in HCC cells. Mechanistically, NRF2 was found to physically bind to the promoter of sonic hedgehog homolog (SHH), which triggers activation of the sonic hedgehog pathway. The effect of NRF2 knockdown was eliminated upon administration of recombinant SHH, demonstrating that NRF2 mediated T-IC function via upregulation of SHH expression. Our study suggests a novel regulatory mechanism for the canonical sonic hedgehog pathway that may function through the NRF2/SHH/GLI signaling axis, thus mediating T-IC phenotypes.
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http://dx.doi.org/10.1016/j.canlet.2020.02.008DOI Listing
April 2020
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