Publications by authors named "Remant K C"

13 Publications

  • Page 1 of 1

Therapeutic delivery of siRNA with polymeric carriers to down-regulate STAT5A expression in high-risk B-cell acute lymphoblastic leukemia (B-ALL).

PLoS One 2021 22;16(6):e0251719. Epub 2021 Jun 22.

Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.

Overexpression and persistent activation of STAT5 play an important role in the development and progression of acute lymphoblastic leukemia (ALL), the most common pediatric cancer. Small interfering RNA (siRNA)-mediated downregulation of STAT5 represents a promising therapeutic approach for ALL to overcome the limitations of current treatment modalities such as high relapse rates and poor prognosis. However, to effectively transport siRNA molecules to target cells, development of potent carriers is of utmost importance to surpass hurdles of delivery. In this study, we investigated the use of lipopolymers as non-viral delivery systems derived from low molecular weight polyethylenimines (PEI) substituted with lauric acid (Lau), linoleic acid (LA) and stearic acid (StA) to deliver siRNA molecules to ALL cell lines and primary samples. Among the lipid-substituted polymers explored, Lau- and LA-substituted PEI displayed excellent siRNA delivery to SUP-B15 and RS4;11 cells. STAT5A gene expression was downregulated (36-92%) in SUP-B15 and (32%) in RS4;11 cells using the polymeric delivery systems, which consequently reduced cell growth and inhibited the formation of colonies in ALL cells. With regard to ALL primary cells, siRNA-mediated STAT5A gene silencing was observed in four of eight patient cells using our leading polymeric delivery system, 1.2PEI-Lau8, accompanied by the significant reduction in colony formation in three of eight patients. In both BCR-ABL positive and negative groups, three of five patients demonstrated marked cell growth inhibition in both MTT and trypan blue exclusion assays using 1.2PEI-Lau8/siRNA complexes in comparison with their control siRNA groups. Three patient samples did not show any positive results with our delivery systems. Differential therapeutic responses to siRNA therapy observed in different patients could result from variable genetic profiles and patient-to-patient variability in delivery. This study supports the potential of siRNA therapy and the designed lipopolymers as a delivery system in ALL therapy.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0251719PLOS
June 2021

Investigation of water-insoluble hydrophobic polyethylenimines as RNAi vehicles in chronic myeloid leukemia therapy.

J Biomed Mater Res A 2021 May 8. Epub 2021 May 8.

Department of Chemical and Materials Engineering, Faculty of Engineering, University of Alberta, Edmonton, Canada.

The discovery of RNA interference (RNAi) more than two decades ago opened avenues for avant-garde cancer treatments that possess the ability to evade issues hampering current chemotherapeutic strategies, owing to its specific gene sequence-driven mechanism of action. A potent short interfering RNA (siRNA) delivery vehicle designed to overcome physiological barriers is imperative for successful RNAi therapy. For this purpose, this study explored the characteristics and therapeutic efficacy of low-molecular weight (MW) polyethylenimine (PEI) with high cholesterol substitution, yielding water-insoluble polymers, in chronic myeloid leukemia (CML) K562 cells. A strong impact of cholesterol grafting on the physicochemical attributes of the resultant polymers and their corresponding complexes with siRNA was observed, with the siRNA binding capacity of polymers increasing and complex dissociation sensitivity decreasing with increase in cholesterol content of the polymers. The modified polymer complexes were significantly smaller in size and possessed higher cationic charge compared to the parent polymer. The interaction with anionic heparan sulfate preoteoglycans present on the cell surface was significant in cellular uptake of the complexes. The therapeutic efficacy of siRNA/polymer complexes was reflected in their ability to effectively silence the reporter green fluorescent protein gene and endogenous CML oncogene BCR-ABL as well as significantly inhibit colony formation by K562 cells post BCR-ABL silencing. The results of this study demonstrated beneficial effects of high levels of hydrophobic substitution on low MW PEI on their functional performance bestowing them the potential to be potent RNAi agents for CML therapy.
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http://dx.doi.org/10.1002/jbm.a.37214DOI Listing
May 2021

Cholesterol grafted cationic lipopolymers: Potential siRNA carriers for selective chronic myeloid leukemia therapy.

J Biomed Mater Res A 2020 03 26;108(3):565-580. Epub 2019 Nov 26.

Department of Chemical & Material Engineering, Faculty of Engineering, University of Alberta, Edmonton, Alberta, Canada.

Synthetic siRNA technology has emerged as a promising approach for molecular therapy of cancer but, despite its potential for post-transcriptional gene silencing, there is an urgent need to develop efficient delivery systems particularly for difficult-to-transfect, anchorage-independent cells. In this study, we designed highly hydrophobic cationic lipopolymers by grafting cholesterol (Chol) onto low-molecular weight (0.6, 1.2, and 2.0 kDa) polyethylenimines (PEIs) to enable specific siRNA therapy to chronic myeloid leukemia (CML) cells. The siRNA binding by PEI-Chol led to nano-sized (100-200 nm diameter) polyplexes with enhanced ζ-potential (+20 to +35 mV) and ability to protect the loaded siRNA completely in fresh serum. The siRNA delivery to CML (K562) cells was proportional to degree of substitution and, unexpectedly, inversely proportional to molecular size of the polymeric backbone. Chol grafting with as little as ~1.0 Chol/PEI on 0.6 and 1.2 kDa PEIs enabled silencing of the reporter Green Fluorescent Protein gene as well as the endogenous BCR-Abl oncogene in K562 cells. The PEI-Chol mediated delivery of siRNAs specific for BCR-Abl and KSP genes significantly arrested the growth the cells which was significantly reflected in colony formation potency of K562 cells. BCR-Able siRNA mediated therapeutic efficacy was also observed in significantly increased caspase activity and apoptosis of K562 cells. Thus, Chol-grafted low-molecular weight PEIs appear to be unique siRNA carriers to realize the molecular therapy in CML cells.
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http://dx.doi.org/10.1002/jbm.a.36837DOI Listing
March 2020

Current outlook on drug resistance in chronic myeloid leukemia (CML) and potential therapeutic options.

Drug Discov Today 2019 07 15;24(7):1355-1369. Epub 2019 May 15.

Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada; Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada; Department of Biomedical Engineering, University of Alberta, Edmonton, AB, Canada. Electronic address:

Chronic myeloid leukemia cells are armed with several resistance mechanisms that can make current drugs ineffective. A better understanding of resistance mechanisms is yielding new approaches to management of the disease. Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm the hallmark of which, the breakpoint cluster region-Abelson (BCR-ABL) oncogene, has been the target of tyrosine kinase inhibitors (TKIs), which have significantly improved the survival of patients with CML. However, because of an increase in TKI resistance, it is becoming imperative to identify resistance mechanisms so that drug therapies can be better prescribed and new agents developed. In this review, we discuss the various BCR-ABL-dependent and -independent mechanisms of resistance observed in CML, and the range of therapeutic solutions available to overcome such resistance and to ultimately improve the survival of patients with CML.
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http://dx.doi.org/10.1016/j.drudis.2019.05.007DOI Listing
July 2019

siRNA Library Screening to Identify Complementary Therapeutic Pairs in Triple-Negative Breast Cancer Cells.

Methods Mol Biol 2019 ;1974:1-19

Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada.

The existence of tightly integrated cross talk through multiple signaling and effector pathways has been appreciated in malignant cells. The realization of the plasticity of such networks is stimulating the development of combinational therapy to overcome the limitations of one-dimensional therapies. Synergistic pairs of siRNAs or siRNA and drug combinations are the new frontiers in identifying effective therapeutic combinations. To elucidate effective combinations, we developed a versatile protocol to screen siRNA libraries in triple-negative breast cancer cell models. This protocol outlines the steps to identify synergistic combinations of siRNA-siRNA or siRNA-drug combinations using siRNA libraries via a robotic screen. By focusing on smaller functional siRNA libraries, we present methodologies to identify synergistic siRNA pairings against cancerous cell growth and molecular targets to augment the activity of pro-apoptotic TRAIL protein. Here, we summarize the critical steps to undertake such combinational target identification, emphasizing critical factors that affect the outcome of the screens. Our experience suggests that siRNA library screening is an efficient protocol to identify complementary therapeutic pairs of new or already-existing drugs. This protocol is simple, robust and can be completed within a 1-week working period.
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http://dx.doi.org/10.1007/978-1-4939-9220-1_1DOI Listing
November 2019

Additive Polyplexes to Undertake siRNA Therapy against CDC20 and Survivin in Breast Cancer Cells.

Biomacromolecules 2018 11 2;19(11):4193-4206. Epub 2018 Oct 2.

Small interfering RNA (siRNA) delivered to silence overexpressed genes associated with malignancies is a promising targeted therapy to decrease the uncontrolled growth of malignant cells. To create potent delivery agents for siRNA, here we formulated additive polyplexes of siRNA using linoleic acid-substituted polyethylenimine and additive polymers (hyaluronic acid, poly(acrylic acid), dextran sulfate, and methyl cellulose) and characterized their physicochemical properties and effectiveness. Incorporating polyanionic polymer along with anionic siRNA in polyplexes was found to decrease the ζ-potential of polyplexes but enhance the cellular delivery of siRNA. The CDC20 and survivin siRNAs delivered by additive polyplexes showed promising efficacy in breast cancer MDA-MB-231, SUM149PT, MDA-MB-436, and MCF7 cells. However, the side effects of the siRNA delivery were observed in nonmalignant cells, and a careful formulation of siRNA/polymer polyplexes was needed to minimize side effects on normal cells. Because the efficacy of siRNA delivery by additive polyplexes was independent of breast cancer phenotypes used in this study, these polyplexes could be further developed to treat a wide range of breast cancers.
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http://dx.doi.org/10.1021/acs.biomac.8b00918DOI Listing
November 2018

Combinational siRNA delivery using hyaluronic acid modified amphiphilic polyplexes against cell cycle and phosphatase proteins to inhibit growth and migration of triple-negative breast cancer cells.

Acta Biomater 2018 01 26;66:294-309. Epub 2017 Nov 26.

Faculty of Pharmacy & Pharmaceutical Sciences, U. of Alberta, Edmonton, AB, Canada; Department of Chemical & Materials Engineering, Faculty of Engineering, U. of Alberta, Edmonton, AB, Canada; Department of Biomedical Engineering, Faculty of Medicine & Dentistry, U. of Alberta, Edmonton, AB, Canada. Electronic address:

Triple-negative breast cancer is an aggressive form of breast cancer with few therapeutic options if it recurs after adjuvant chemotherapy. RNA interference could be an alternative therapy for metastatic breast cancer, where small interfering RNA (siRNA) can silence the expression of aberrant genes critical for growth and migration of malignant cells. Here, we formulated a siRNA delivery system using lipid-substituted polyethylenimine (PEI) and hyaluronic acid (HA), and characterized the size, ζ-potential and cellular uptake of the nanoparticulate delivery system. Higher cellular uptake of siRNA by the tailored PEI/HA formulation suggested better interaction of complexes with breast cancer cells due to improved physicochemical characteristics of carrier and HA-binding CD44 receptors. The siRNAs against specific phosphatases that inhibited migration of MDA-MB-231 cells were then identified using library screen against 267 protein-tyrosine phosphatases, and siRNAs to inhibit cell migration were further validated. We then assessed the combinational delivery of a siRNA against CDC20 to decrease cell growth and a siRNA against several phosphatases shown to decrease migration of breast cancer cells. Combinational siRNA therapy against CDC20 and identified phosphatases PPP1R7, PTPN1, PTPN22, LHPP, PPP1R12A and DUPD1 successfully inhibited cell growth and migration, respectively, without interfering the functional effect of the co-delivered siRNA. The identified phosphatases could serve as potential targets to inhibit migration of highly aggressive metastatic breast cancer cells. Combinational siRNA delivery against cell cycle and phosphatases could be a promising strategy to inhibit both growth and migration of metastatic breast cancer cells, and potentially other types of metastatic cancer.

Statement Of Significance: The manuscript investigated the efficacy of a tailored polymeric siRNA delivery system formulation as well as combinational siRNA therapy in metastatic breast cancer cells to inhibit malignant cell growth and migration. The siRNA delivery was undertaken by non-viral means with PEI/HA. We identified six phosphatases that could be critical targets to inhibit migration of highly aggressive metastatic breast cancer cells. We further report on specifically targeting cell cycle and phosphatase proteins to decrease both malignant cell growth and migration simultaneously. Clinical gene therapy against metastatic breast cancer with effective and safe delivery systems is urgently needed to realize the potential of molecular medicine in this deadly disease and our studies in this manuscript is intended to facilitate this endeavor.
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http://dx.doi.org/10.1016/j.actbio.2017.11.036DOI Listing
January 2018

Biomaterials to Facilitate Delivery of RNA Agents in Bone Regeneration and Repair.

ACS Biomater Sci Eng 2017 Jul 12;3(7):1195-1206. Epub 2016 Oct 12.

Department of Chemical & Materials Engineering, Faculty of Engineering, Department of Biomedical Engineering, Faculty of Medicine & Dentistry, and Faculty of Pharmacy & Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta T6G 2R3, Canada.

Bone healing after traumatic injuries or pathological diseases remains an important worldwide problem. In search of safer and more effective approaches to bone regeneration and repair, RNA-based therapeutic agents, specifically microRNAs (miRNAs) and short interfering RNA (siRNA), are beginning to be actively explored. In this review, we summarize current attempts to employ miRNAs and siRNAs in preclinical models of bone repair. We provide a summary of current limitations when attempting to utilize bioactive nucleic acids for therapeutic purposes and position the unique aspects of RNA reagents for clinical bone repair. Delivery strategies for RNA reagents are emphasized and nonviral carriers (biomaterial-based) employed to deliver such reagents are reviewed. Critical features of biomaterial carriers and various delivery technologies centered around nanoparticulate systems are highlighted. We conclude with the authors' perspectives on the future of the field, outlining main critical issues important to address as RNA reagents are explored for clinical applications.
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http://dx.doi.org/10.1021/acsbiomaterials.6b00387DOI Listing
July 2017

Nucleic acid combinations: A new frontier for cancer treatment.

J Control Release 2017 06 24;256:153-169. Epub 2017 Apr 24.

Department of Chemical & Material Engineering, Faculty of Engineering, University of Alberta, Edmonton, AB, Canada; Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada; Department of Biomedical Engineering, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, Canada. Electronic address:

The emerging molecular understanding of cancer cell behavior is leading to increasing possibilities to control unchecked cell growth and metastasis. On the other hand, development of multifunctional drug carriers at the 'nano'-scale is providing exciting new therapeutic strategies in clinical management of cancer beyond the conventional cytotoxic drugs. A new frontier in this regard is the combinational use of complementary agents based on nucleic acids to overcome the limitations of conventional therapy. The existence of tightly-integrated cross-talk through multiple signaling and effector pathways have been appreciated for some time, and the plasticity of such a network to overcome one-dimensional intervention is stimulating development of combinational therapy. The objective of this review is to underline the cutting edge technologies and opportunities employed in combination cancer therapy using nucleic acids therapeutics for successful clinical translation. Here, we provide a detailed analysis of the multifunctional carriers designed for different types of payloads, surveying the biomaterials used to construct the functional carriers. We then provide effective nucleic acid combinations employed to obtain more comprehensive outcomes, highlighting the critical factors involved in successful therapy. We conclude with an authors' perspective on the future of combinational therapy using nucleic acid therapeutics, articulating the main challenges to advance this promising approach to the clinical realm.
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http://dx.doi.org/10.1016/j.jconrel.2017.04.029DOI Listing
June 2017

Multiple siRNA delivery against cell cycle and anti-apoptosis proteins using lipid-substituted polyethylenimine in triple-negative breast cancer and nonmalignant cells.

J Biomed Mater Res A 2016 12 9;104(12):3031-3044. Epub 2016 Aug 9.

Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada.

Conventional breast cancer therapies have significant limitations that warrant a search for alternative therapies. Short-interfering RNA (siRNA), delivered by polymeric biomaterials and capable of silencing specific genes critical for growth of cancer cells, holds great promise as an effective, and more specific therapy. Here, we employed amphiphilic polymers and silenced the expression of two cell cycle proteins, TTK and CDC20, and the anti-apoptosis protein survivin to determine the efficacy of polymer-mediated siRNA treatment in breast cancer cells as well as side effects in nonmalignant cells in vitro. We first identified effective siRNA carriers by screening a library of lipid-substituted polyethylenimines (PEI), and PEI substituted with linoleic acid (LA) emerged as the most effective carrier for selected siRNAs. Combinations of TTK/CDC20 and CDC20/Survivin siRNAs decreased the growth of MDA-MB-231 cells significantly, while only TTK/CDC20 combination inhibited MCF7 cell growth. The effects of combinational siRNA therapy was higher when complexes were formulated at lower siRNA:polymer ratio (1:2) compared to higher ratio (1:8) in nonmalignant cells. The lead polymer (1.2PEI-LA6) showed differential transfection efficiency based on the cell-type transfected. We conclude that the lipid-substituted polymers could serve as a viable platform for delivery of multiple siRNAs against critical targets in breast cancer therapy. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 3031-3044, 2016.
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http://dx.doi.org/10.1002/jbm.a.35846DOI Listing
December 2016

Dual secured nano-melittin for the safe and effective eradication of cancer cells.

J Mater Chem B 2015 Jan 28;3(1):25-29. Epub 2014 Oct 28.

Department of Drug Discovery and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, 715 Sumter St., Columbia, SC 29208, USA.

The clinical application of natural and synthetic amphipathic peptides (e.g., melittin) for cancer therapy is hindered by their notorious side effect, lysing red blood cells. To safely deliver a therapeutic peptide to the tumor tissue and kill cancer cells, we developed an environment-sensitive peptide delivery system, dual secured nano-sting (DSNS), through the combination of a zwitterionic glycol chitosan and disulfide bonds. Melittin loaded DSNS could kill almost 100% of MCF-7, HCT-116, SKOV-3, and NCI/ADR-RES (multidrug resistant) cancer cells at the concentration of 5 μM, while not showing any hemolytic effect.
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http://dx.doi.org/10.1039/C4TB01401DDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4342614PMC
January 2015

pH and redox dual responsive nanoparticle for nuclear targeted drug delivery.

Mol Pharm 2012 Sep 22;9(9):2719-29. Epub 2012 Aug 22.

Department of Pharmaceutical and Biomedical Sciences, South Carolina College of Pharmacy, University of South Carolina, 715 Sumter Street, Columbia, South Carolina 29208, United States.

To mimic the clinic dosing pattern, initially administering high loading dose and then low maintenance dose, we designed a novel poly(2-(pyridin-2-yldisulfanyl)ethyl acrylate) (PDS) based nanoparticle delivery system. Side chain functional PDS was synthesized by free radical polymerization. Polyethylene glycol and cyclo(Arg-Gly-Asp-d-Phe-Cys) (cRGD) peptide was conjugated to PDS through thiol-disulfide exchange reaction to achieve RPDSG polymer. RPDSG/DOX, RPDSG nanoparticle loaded with doxorubicin, was fabricated by cosolvent dialysis method. The size of the nanoparticles was 50.13 ± 0.5 nm in PBS. The RPDSG/DOX nanoparticle is stable in physiological condition while quickly releasing doxorubicin with the trigger of acidic pH and redox potential. Furthermore, it shows a two-phase release kinetics, providing both loading dose and maintenance dose for cancer therapy. The conjugation of RGD peptide enhanced the cellular uptake and nuclear localization of the RPDSG/DOX nanoparticles. RPDSG/DOX exhibits IC(50) close to that of free doxorubicin for HCT-116 colon cancer cells. Due to the synergetic effect of RGD targeting effect and its two-phase release kinetics, RPDSG/DOX nanoparticles display significantly higher anticancer efficacy than that of free DOX at concentrations higher than 5 μM. These results suggest that RPDSG/DOX could be a promising nanotherapeutic for tumor-targeted chemotherapy.
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http://dx.doi.org/10.1021/mp300274gDOI Listing
September 2012

Synthesis and characterization of thermally responsive Pluronic F127-chitosan nanocapsules for controlled release and intracellular delivery of small molecules.

ACS Nano 2010 Nov 1;4(11):6747-59. Epub 2010 Nov 1.

Department of Mechanical Engineering, University of South Carolina, Columbia, South Carolina 29208, United States.

In this study, we synthesized empty core-shell structured nanocapsules of Pluronic F127 and chitosan and characterized the thermal responsiveness of the nanocapsules in size and wall-permeability. Moreover, we determined the feasibility of using the nanocapsules to encapsulate small molecules for temperature-controlled release and intracellular delivery. The nanocapsules are ∼37 nm at 37 °C and expand to ∼240 nm when cooled to 4 °C in aqueous solutions, exhibiting >200 times change in volume. Moreover, the permeability of the nanocapsule wall is high at 4 °C (when the nanocapsules are swollen), allowing free diffusion of small molecules (ethidium bromide, MW = 394.3 Da) across the wall, while at 37 °C (when the nanocapsules are swollen), the wall-permeability is so low that the small molecules can be effectively withheld in the nanocapsule for hours. As a result of their thermal responsiveness in size and wall-permeability, the nanocapsules are capable of encapsulating the small molecules for temperature-controlled release and intracellular delivery into the cytosol of both cancerous (MCF-7) and noncancerous (C3H10T1/2) mammalian cells. The cancerous cells were found to take up the nanocapsules much faster than the noncancerous cells during 45 min incubation at 37 °C. Moreover, toxicity of the nanocapsules as a delivery vehicle was found to be negligible. The Pluronic F127-chitosan nanocapsules should be very useful for encapsulating small therapeutic agents to treat diseases particularly when it is combined with cryotherapy where the process of cooling and heating between 37 °C and hypothermic temperatures is naturally done.
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http://dx.doi.org/10.1021/nn101617nDOI Listing
November 2010