Gemcitabine-resistant Lines Research Articles

MiRNA signatures underlie chemoresistance in the gemcitabine-resistant pancreatic ductal adenocarcinoma cell line MIA PaCa-2 GR.

Introduction: Chemotherapy resistance remains a significant challenge in the treatment of pancreatic adenocarcinoma (PDAC), particularly in relation to gemcitabine (Gem), a commonly used chemotherapeutic agent. MicroRNAs (miRNAs) are known to influence cancer progression and chemoresistance. This study investigates the association between miRNA expression profiles and gemcitabine resistance in PDAC. Methods: The miRNA expression profiles of a gemcitabine-sensitive (GS) PDAC cell line, MIA PaCa-2, and its gemcitabine-resistant (GR) progeny, MIA PaCa-2 GR, were analyzed. miRNA sequencing (miRNA-seq) was employed to identify miRNAs expressed in these cell lines. Differential expression analysis was performed, and Ingenuity Pathway Analysis (IPA) was utilized to elucidate the biological functions of the differentially expressed miRNAs. Results: A total of 1867 miRNAs were detected across both cell lines. Among these, 97 (5.2%) miRNAs showed significant differential expression between the GR and GS cell lines, with 65 (3.5%) miRNAs upregulated and 32 (1.7%) miRNAs downregulated in the GR line. The most notably altered miRNAs were implicated in key biological processes such as cell proliferation, migration, invasion, chemosensitization, alternative splicing, apoptosis, and angiogenesis. A subset of these miRNAs was further analyzed in patient samples to identify potential markers for recurrent tumors. Discussion: The differential miRNA expression profiles identified in this study highlight the complex regulatory roles of miRNAs in gemcitabine resistance in PDAC. These findings suggest potential targets for improving prognosis and tailoring treatment strategies in PDAC patients, particularly those showing resistance to gemcitabine. Future research should focus on validating these miRNAs as biomarkers for resistance and exploring their therapeutic potential in overcoming chemoresistance.

Abstract A080: Target genes in pancreatic cancer cells of the pan-quadruplex clinical candidate compound QN-302 revealed by comparative transcriptome profiling

Abstract QN-302 is a tetra-substituted naphthalene derivative designed to have high affinity to quadruplexes in cancer-related genes, which have multiple quadruplex occurrence in their promoter sequences. QN-302 has ca 1 nM in vitro activity against a panel of pancreatic ductal adenocarcinoma (PDAC) cell lines and shows high activity against four distinct PDAC in vivo models, including the KPC genetic model. QN-302 is currently being developed for clinical trials in solid tumors including PDAC. It has also recently been granted orphan drug drug (ODD) status by the FDA. We have previously reported on whole-genome transcriptome studies for QN-302, which show that it selectively targets quadruplex-rich genes in PDAC-related pathways, and thus acts as a pan-quadruplex agent. We have recently extended our analysis to include two closely related analogs of QN-302 as well as data from a gemcitabine-resistant line. QN-302 is consistently ca 10-fold more potent in PDAC cells and in vivo than the second-best analog. RNA-seq whole-cell and comparative bioinformatics analyses have been used to probe these differences. This has resulted in the identification of those target genes that the naphthalene diimide family have in common, many of which are involved in PDAC pathways such as hedgehog, axon guidance, WNT/β-catenin and hippo. It has also been possible to identify a small number of quadruplex target genes that are highly and selectively down-regulated by QN-302, and which are also highly up-regulated in human PDAC. We suggest that these contribute to the exceptional in vivo potency of this compound. Citation Format: Ahmed Ahmed, Tariq Arshad, Maria Roman-Escorza, Dan M. Neidle, Stephen Neidle. Target genes in pancreatic cancer cells of the pan-quadruplex clinical candidate compound QN-302 revealed by comparative transcriptome profiling [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr A080.

A G-quadruplex-binding compound shows potent activity in human gemcitabine-resistant pancreatic cancer cells

Gemcitabine is a drug of choice in the treatment of human pancreatic cancer. Chemo-resistance to this drug is common and has been attributed to a variety of distinct mechanisms, involving > 100 genes. A recently developed small-molecule G-quadruplex ligand, the trisubstituted naphthalene diimide compound CM03, has previously been shown to have equivalent potency to gemcitabine in the pancreatic cancer cell line MIA PaCa-2. We report here on cell lines of increased resistance to gemcitabine that have been generated from this line, with the most resistant having 1,000-fold reduced sensitivity to gemcitabine. These resistant lines retain nM sensitivity to CM03. The molecular basis for the retention of potency by this G-quadruplex ligand has been examined using whole transcriptome data analysis with RNA-seq. This has revealed that the pattern of pathways down regulated by CM03 in the parental MIA PaCa-2 cell line is largely unaffected in the gemcitabine-resistant line. The analysis has also shown that the expression patterns of numerous genes involved in gemcitabine sensitivity are down regulated in the resistant line upon CM03 treatment. These results are supportive of the concept that G-quadruplex small molecules such as CM03 have potential for clinical use in the treatment of gemcitabine-resistant human pancreatic cancer.

Abstract 2114: Glycosyltransferase ST6Gal-I protects against chemotherapy induced DNA damage and subsequent apoptosis in pancreatic adenocarcinoma cells

Abstract ST6Gal-I is a sialyltransferase that adds α2-6 linked sialic acids to cell surface proteins as they pass through the trans-Golgi. Sialic acids, being negatively charged, are able to alter the function of selected cell surface receptors, which leads to dysregulation of various downstream cellular pathways. Overexpression of ST6Gal-I has been observed in various cancers including ovarian and pancreatic cancer. We have previously shown that knockdown of ST6Gal-I expression increases ovarian cancer cell susceptibility to the chemotherapeutic drug cisplatin. In the present study we further investigate whether resistance to additional drugs such as gemcitabine, the front line treatment for pancreatic cancer, is affected by ST6Gal-I activity. MiaPaCa-2 and BxPC3 pancreatic cancer cell lines, having high ST6Gal-I expression, were employed for our studies. To elucidate the mechanistic role of ST6Gal-I in gemcitabine resistance we created stable ST6Gal-I knockdown lines of MiaPaCa-2 and BxPC3 cells. Gemcitabine induced cell death was more pronounced in the knockdown cell lines, indicated by heightened activation of caspase-3. Gemcitabine is metabolized to a nucleoside analogue, gemcitabine triphosphate, which induces apoptosis by promoting DNA damage. Increased single stand DNA damage in the knockdown cells was confirmed using alkaline comet assay. Gemcitabine treatment led to greater activation of DNA damage markers and response elements (γH2AX, phospho CHK1, phospho CHK2), along with increased levels of cleaved caspase-3 in the knockdown cells as compared to empty vector control cells. We next developed a stable gemcitabine resistant MiaPaCa-2 cell line by growing parental cells in gemcitabine. We selected for the population of cells that survived and were able to replicate in gemcitabine containing media. ST6Gal-I levels were found to be increased in the stable gemcitabine resistant lines relative to parental cell lines, suggesting that cells with high ST6Gal-I expression selectively survive gemcitabine treatment. By measuring the levels of genes involved in activation over those responsible for inactivation of gemcitabine, we were able to obtain a gemcitabine sensitivity predictive ratio for MiaPaCa-2 and BxPC3 ST6Gal-I knockdown, empty vector, parental and stable gemcitabine resistant cell lines. This ratio has been described previously in literature as a metric for gauging gemcitabine resistance. According to the ratios obtained, ST6Gal-I knockdown enhanced drug sensitivity whereas high expression of ST6Gal-I offered protection against gemcitabine induced apoptosis. Collectively these data indicate that upregulation of ST6Gal-I imparts tumor cell survival through prevention of gemcitabine induced DNA damage. Citation Format: Asmi Chakraborty, Matthew Schultz, Hoa Q. Trummell, James A. Bonner, Susan Bellis. Glycosyltransferase ST6Gal-I protects against chemotherapy induced DNA damage and subsequent apoptosis in pancreatic adenocarcinoma cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2114.