Publications by authors named "Thupten Tsering"

9 Publications

  • Page 1 of 1

Acetylsalicylic Acid Exerts Potent Antitumor and Antiangiogenic Effects in Cutaneous and Uveal Melanoma Cell Lines.

Ocul Oncol Pathol 2020 Dec 4;6(6):442-455. Epub 2020 Nov 4.

Henry C. Witelson Ocular Pathology Laboratory, McGill University, Montreal, Québec, Canada.

Introduction: Acetylsalicylic acid (ASA) has been investigated for a potential anticancer role in several cancers, such as colorectal, ovarian, and endometrial cancer. Moreover, ASA has been shown to abrogate various processes that contribute to tumor growth and progression.

Objective: The aim of this study was to evaluate the effects of ASA on cutaneous melanoma (CM) and uveal melanoma (UM).

Methods: Human CM and UM cells were treated with 5 mM ASA and assessed for changes in cellular functions. Antiangiogenic effects of ASA were determined using an ELISA-based assay for 10 proangiogenic cytokines, and then validated by Western blot. Finally, proteomic analysis of ASA-treated cells was performed to elucidate the changes that may be responsible for ASA-mediated effects in melanoma cells.

Results: Treatment with ASA significantly inhibited the proliferation, invasion, and migration capabilities, and caused a significant decrease in angiogenin and PIGF secretion in both CM and UM. Mass spectrometry revealed 179 protein changes associated with ASA in the CM and UM cell lines.

Conclusions: These results suggest that ASA may be effective as an adjuvant therapy in metastatic CM and UM. Future studies are needed to determine the regulating targets that are responsible for the antitumor effects of ASA.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1159/000510582DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7772880PMC
December 2020

The effect of different organic solvents in liposome properties produced in a periodic disturbance mixer: Transcutol®, a potential organic solvent replacement.

Colloids Surf B Biointerfaces 2021 Feb 4;198:111447. Epub 2020 Nov 4.

Department of Electrical Engineering, École de technologie supérieure, 1100 Notre Dame-West, Montreal, QC H3C 1K3, Canada.

Liposomes are versatile particles used in the biomedical field as drug delivery systems (DDS). Liposome production using micromixers have shown to yield nanoparticles for DDS in a single step with a controllable size by changing flow conditions. Nonetheless, other factors such as the organic solvent, play a crucial role in the liposome formation process. Furthermore, drug solubility and toxicity are pivotal when deciding which organic solvent to choose. In this work, liposomes were produced in a periodic disturbance mixer (PDM). We investigated three conventional organic solvents: ethanol, methanol, and isopropanol as well as Transcutol®. We assessed the organic solvent influence on liposome characteristics (size, size distribution and zeta potential). Among the four organic solvents, Transcutol® yielded the smallest liposomes, which ranged from 80 nm to 160 nm. Moreover, a more in-depth investigation showed that Transcutol® produced smaller or similar-sized particles under different temperature and lipid concentration conditions, compared with ethanol. Furthermore, we proved that particles zeta potential was not influenced by the organic solvent, production temperature, or lipid concentration. This work results show that Transcutol® could replace the conventional alcohol-based solvents and can potentially avoid filtration steps due to its low toxicity. Therefore, the present approach is appealing for DDS development.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.colsurfb.2020.111447DOI Listing
February 2021

Uveal Melanoma-Derived Extracellular Vesicles Display Transforming Potential and Carry Protein Cargo Involved in Metastatic Niche Preparation.

Cancers (Basel) 2020 Oct 11;12(10). Epub 2020 Oct 11.

Cancer Research Program, Research Institute of the McGill University Health Centre, 1001 Decarie Blvd, Montreal, QC H4A 3J1, Canada.

Extracellular vesicles (EVs) carry molecules derived from donor cells and are able to alter the properties of recipient cells. They are important players during the genesis and progression of tumors. Uveal melanoma (UM) is the most common primary intraocular tumor in adults and is associated with a high rate of metastasis, primarily to the liver. However, the mechanisms underlying this process are poorly understood. In the present study, we analyzed the oncogenic potential of UM-derived EVs and their protein signature. We isolated and characterized EVs from five UM cell lines and from normal choroidal melanocytes (NCMs). BRCA1-deficient fibroblasts (Fibro-BKO) were exposed to the EVs and analyzed for their growth in vitro and their reprograming potential in vivo following inoculation into NOD-SCID mice. Mass spectrometry of proteins from UM-EVs and NCM-EVs was performed to determine a protein signature that could elucidate potential key players in UM progression. In-depth analyses showed the presence of exosomal markers, and proteins involved in cell-cell and focal adhesion, endocytosis, and PI3K-Akt signaling pathway. Notably, we observed high expression levels of HSP90, HSP70 and integrin V in UM-EVs. Our data bring new evidence on the involvement of UM-EVs in cancer progression and metastasis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/cancers12102923DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7600758PMC
October 2020

Extracellular vesicles from genetically unstable, oncogene-driven cancer cells trigger micronuclei formation in endothelial cells.

Sci Rep 2020 05 22;10(1):8532. Epub 2020 May 22.

Research Institute of the McGill University Health Centre, McGill University, Montreal, QC, H4A 3J1, Canada.

Oncogenic transformation impacts cancer cell interactions with their stroma, including through formation of abnormal blood vessels. This influence is often attributed to angiogenic growth factors, either soluble, or associated with tumor cell-derived extracellular vesicles (EVs). Here we examine some of the cancer-specific components of EV-mediated tumor-vascular interactions, including the impact of genetic driver mutations and genetic instability. Cancer cells expressing mutant HRAS oncogene exhibit aberrations of chromatin architecture, aneuploidy, cytoplasmic chromatin deposition and formation of micronuclei with a non-random chromosome content. EVs released from such HRAS-driven cells carry genomic DNA, including oncogenic sequences, and transfer this material to endothelial cells while inducing abnormal formation of micronuclei, along with cell migration and proliferation. Micronuclei were also triggered following treatment with EVs derived from glioma cells (and stem cells) expressing EGFRvIII oncogene, and in both endothelial cells and astrocytes. EVs from HRAS and EGFRvIII-driven cancer cells carry 19 common proteins while EVs from indolent control cells exhibit more divergent proteomes. Immortalized endothelial cell lines with disrupted TP53 pathway were refractory to EV-mediated micronuclei induction. We suggest that oncogenic transformation and intercellular trafficking of cancer-derived EVs may contribute to pathological vascular responses in cancer due to intercellular transmission of genomic instability.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41598-020-65640-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7244541PMC
May 2020

Leukobiopsy - A Possible New Liquid Biopsy Platform for Detecting Oncogenic Mutations.

Front Pharmacol 2019 24;10:1608. Epub 2020 Jan 24.

Montreal Children's Hospital, RI MUHC, McGill University, Montreal, QC, Canada.

Detection of unique oncogenic alterations encoded by the sequence or biochemical modification in cancer-associated transforming macromolecules has revolutionized diagnosis, classification and management of human cancers. While these signatures were traditionally regarded as largely intracellular and confined to the tumor mass, oncogenic mutations and actionable cancer-related molecular alterations can also be accessed remotely through their recovery from biofluids of either rare circulating tumor cells (CTCs), or of more abundant non-cellular carriers, such as extracellular vesicles (EVs), protein complexes, or cell-free tumor DNA (ctDNA). Tumor-related macromolecules may also accumulate in circulating platelets. Collectively, these approaches are known as liquid biopsy and hold promise as non-invasive, real-time opportunities to access to the evolving molecular landscape of human malignancies. More recently, a possibility of recovering cancer-specific DNA sequences from circulating leukocytes has also been postulated using experimental models. While it is often assumed that these and other liquid biopsy approaches rely on material passively shed from the tumor mass or its debris, recent evidence suggests that several regulated processes contribute to the abundance, nature, half-life, and turnover of different circulating cancer-related molecular signals. Moreover, many of these signals possess biological activity and may elicit local and systemic regulatory responses. Thus, a better understanding of the biology of liquid biopsy platforms and analytes may enable achieving improved performance of this promising and emerging diagnostic strategy in cancer.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3389/fphar.2019.01608DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6993065PMC
January 2020

Beta-blockers exert potent anti-tumor effects in cutaneous and uveal melanoma.

Cancer Med 2019 12 7;8(17):7265-7277. Epub 2019 Oct 7.

Cancer Research Program, Research Institute of the McGill University Health Centre, Montreal, QC, Canada.

Background: Melanoma is a life-threatening group of cancers mainly affecting the skin (cutaneous melanoma, CM) and the eyes (uveal melanoma, UM). Nearly half of patients with UM develop liver metastases regardless of the primary treatment. For this reason, adjuvant therapy to prevent disease progression is essential to improve survival of patients with melanoma. Beta-adrenoceptors (β-AR) have emerged as novel targets to inhibit tumor growth and dissemination in CM, but have not been investigated in UM.

Methods: The aim of this study was to comprehensively evaluate the effects of a non-selective β-blocker in UM and CM. Propranolol was tested on four UM and two CM cell lines to determine the effects of this beta-blocker. The expression of β-AR in UM was assessed in enucleated eyes of 36 patients.

Results: The results showed that propranolol exerts potent anti-proliferative effects, attenuates migration, reduces VEGF and induces cell cycle arrest and apoptosis in both UM and CM in a dose-dependent manner. Furthermore, levels of cell-free DNA released from the cells correlated to propranolol treatment and may be an indicator of treatment response. Finally, immunohistochemical analysis revealed the expression of β1 and β2 adrenoceptors in all UM patients, with higher expression seen in the more aggressive epithelioid versus less aggressive spindle cells.

Conclusions: Collectively our data suggest that a nonselective beta-blocker may be effective against melanoma. For the first time, we show potent anti-tumor effects in UM cells following propranolol administration and expression of β1 and β2 adrenoceptors in patient tissue.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/cam4.2594DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6885887PMC
December 2019

Resonant Formation of Strand Breaks in Sensitized Oligonucleotides Induced by Low-Energy Electrons (0.5-9 eV).

Angew Chem Int Ed Engl 2017 08 28;56(36):10952-10955. Epub 2017 Jul 28.

Department of Chemistry-Physical Chemistry, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476, Potsdam-Golm, Germany.

Halogenated nucleobases are used as radiosensitizers in cancer radiation therapy, enhancing the reactivity of DNA to secondary low-energy electrons (LEEs). LEEs induce DNA strand breaks at specific energies (resonances) by dissociative electron attachment (DEA). Although halogenated nucleobases show intense DEA resonances at various electron energies in the gas phase, it is inherently difficult to investigate the influence of halogenated nucleobases on the actual DNA strand breakage over the broad range of electron energies at which DEA can take place (<12 eV). By using DNA origami nanostructures, we determined the energy dependence of the strand break cross-section for oligonucleotides modified with 8-bromoadenine ( A). These results were evaluated against DEA measurements with isolated A in the gas phase. Contrary to expectations, the major contribution to strand breaks is from resonances at around 7 eV while resonances at very low energy (<2 eV) have little influence on strand breaks.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/anie.201705504DOI Listing
August 2017

Dose controlled low energy electron irradiator for biomolecular films.

Rev Sci Instrum 2016 Mar;87(3):034302

Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India.

We have developed a multi target, Low Energy Electron (LEE), precise dose controlled irradiator for biomolecular films. Up to seven samples can be irradiated one after another at any preset electron energy and dose under UHV conditions without venting the chamber. In addition, one more sample goes through all the steps except irradiation, which can be used as control for comparison with the irradiated samples. All the samples are protected against stray electron irradiation by biasing them at -20 V during the entire period, except during irradiation. Ethernet based communication electronics hardware, LEE beam control electronics and computer interface were developed in house. The user Graphical User Interface to control the irradiation and dose measurement was developed using National Instruments Lab Windows CVI. The working and reliability of the dose controlled irradiator has been fully tested over the electron energy range of 0.5 to 500 eV by studying LEE induced single strand breaks to ΦX174 RF1 dsDNA.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1063/1.4944812DOI Listing
March 2016

Ethnically distinct populations of historical Tibet exhibit distinct autosomal STR compositions.

Gene 2016 Mar 11;578(1):74-84. Epub 2015 Dec 11.

Department of Molecular Biology, Colorado College, Colorado Springs, CO, USA.

At an average altitude of 4000m above sea level, the Tibetan plateau is one of the highest plains on the planet. It is surrounded on three sides by massive mountain ranges: the Kunlun, the Karakoram and the Himalayas. These natural barriers have kept Tibet relatively isolated. In the present study, 15 autosomal STR loci were genotyped in 338 unrelated individuals from three traditional provinces of historical Tibet: Amdo (86), Kham (101) and U-Tsang (151). All the studied loci were in Hardy-Weinberg equilibrium except for the D19S433 locus in the Kham province. FGA, D21S11 and D2S1338 show the highest observed heterozygosity values in Amdo (0.8954), Kham (0.9208) and U-Tsang (0.8940), respectively, whereas TPOX is the least variable marker displaying the lowest value for the same parameter. U-Tsang exhibits the highest total numbers of alleles (139) followed by Kham (130) and Amdo (128) groups. The allele frequency data from this study were compared to relevant global reference populations. Our results indicate that although these three Tibetan populations group together in both the Correspondence Analysis (CA) plot and the Neighbor Joining (NJ) tree, they exhibit some degree of genetic differentiation among themselves congruent with their unique dialects, cultures and traditions. The 15 autosomal STR loci studied were found to be informative and discriminating, thereby providing a useful set of markers for population genetic studies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.gene.2015.12.009DOI Listing
March 2016