Browsing by Author "Akbar, Muhammad Waqas"
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Item Open Access Characterization of chemosensitivity profiles of breast cancer cell lınes, with and without stem cell like features = Kök-hücre özelliği olan ve olmayan meme kanseri hücre hatlarının ilaç hassasiyet profillerinin tanımlanması(Bilkent University, 2014) Akbar, Muhammad WaqasBreast cancer is the second most common cause of death worldwide from cancer due to complications with its diagnosis and resistance to therapy. Recent studies have shown that breast tumors when compared with other solid tumors also contain a subpopulation termed as cancer stem cells (CSCs). CSCs are hard to kill due to their therapy resistant capacities. These unharmed cells then result into relapse of tumor after treatment. Some established breast cancer cell lines also behave in similar fashion to CSCs in overall manner thus termed as CSC like cell lines. This study primarily focuses on characterizing CSC like cell lines from non CSC like cell lines based upon their gene expression and prediction of drugs which can target these groups separately. In this study two databases, Cancer Cell Line Encyclopedia (CCLE) and Cancer Genome Project (CGP), were used which contain gene expression data and drugs cytotoxicity data for most of the established cancer cell lines. Breast cancer cell lines gene expression data was used to predict two gene lists which can separate breast cancer cell lines into CSC like and non CSC like cell lines by in silico analysis. These gene lists were named as Patentable and Non Patentable. Additionally four drugs were predicted which can target CSC like group (Midostaurin and Elesclomol) and non CSC like group (Panobinostat and Lapatinib) separately. Later these findings were validated in vitro. Non Patentable gene list could not be validated due to low concordance with microarray data. On the other hand, Patentable gene list was validated and was found concordant with microarray data. Out of four selected drugs, Panobinostat and Lapatinib showed increased toxicity to non CSC like cell lines while only Midostaurin showed toxicity to CSC like cell lines. To investigate further that cell lines were grown in 3D cell culture conditions, to increase their stem cell like properties (stemness). But only one cell line MDA-MB-157 which was found as CSC like, showed expected behavior. Additionally this cell line increased resistance to Lapatinib and Panobinostat and became more sensitive to Midostaurin. Correlation analysis showed some genes as potential biomarkers for selected drugs. In conclusion, in this study various genes are proposed to differentiate CSC like cell lines from non CSC like cell lines. And Midostaurin can be potential drug to treat CSC like cells while Lapatinib and Panobinostat showed increased activity against non CSC like cell lines.Item Open Access Epithelial-to-mesenchymal transition is not a major modulating factor in the cytotoxic response to natural products in cancer cell lines(MDPI AG, 2021-09-27) Küçükkaraduman, Barş; Çiçek, Ekin Gökçe; Akbar, Muhammad Waqas; Demirkol Canlı, Seçil; Vural, Burçak; Gure, Ali OsmayNumerous natural products exhibit antiproliferative activity against cancer cells by modulating various biological pathways. In this study, we investigated the potential use of eight natural compounds (apigenin, curcumin, epigallocatechin gallate, fisetin, forskolin, procyanidin B2, resveratrol, urolithin A) and two repurposed agents (fulvestrant and metformin) as chemotherapy enhancers and mesenchymal-to-epithelial (MET) inducers of cancer cells. Screening of these compounds in various colon, breast, and pancreatic cancer cell lines revealed anti-cancer activity for all compounds, with curcumin being the most effective among these in all cell lines. Although some of the natural products were able to induce MET in some cancer cell lines, the MET induction was not related to increased synergy with either 5-FU, irinotecan, gemcitabine, or gefitinib. When synergy was observed, for example with curcumin and irinotecan, this was unrelated to MET induction, as assessed by changes in E-cadherin and vimentin expression. Our results show that MET induction is compound and cell line specific, and that MET is not necessarily related to enhanced chemosensitivity.Item Open Access A novel 20-gene prognostic score in pancreatic adenocarcinoma(Public Library of Science, 2020) Demirkol-Canlı, S.; Dedeoğlu, Ege; Akbar, Muhammad Waqas; Küçükkaraduman, Barış; İşbilen, Murat; Şükrüoğlu-Erdoğan, Ö.; Kılıç-Erciyas, S.; Yazıcı, H.; Vural, B.; Güre, Ali OsmayPancreatic ductal adenocarcinoma (PDAC) is among the most lethal cancers. Known risk factors for this disease are currently insufficient in predicting mortality. In order to better prognosticate patients with PDAC, we identified 20 genes by utilizing publically available high-throughput transcriptomic data from GEO, TCGA and ICGC which are associated with overall survival and event-free survival. A score generated based on the expression matrix of these genes was validated in two independent cohorts. We find that this “Pancreatic cancer prognostic score 20 –PPS20” is independent of the confounding factors in multivariate analyses, is dramatically elevated in metastatic tissue compared to primary tumor, and is higher in primary tumors compared to normal pancreatic tissue. Transcriptomic analyses show that tumors with low PPS20 have overall more immune cell infiltration and a higher CD8 T cell/Treg ratio when compared to those with high PPS20. Analyses of proteomic data from TCGA PAAD indicated higher levels of Cyclin B1, RAD51, EGFR and a lower E-cadherin/Fibronectin ratio in tumors with high PPS20. The PPS20 score defines not only prognostic and biological sub-groups but can predict response to targeted therapy as well. Overall, PPS20 is a stronger and more robust transcriptomic signature when compared to similar, previously published gene lists.Item Open Access Prediction of prognosis and chemosensitivity in breast cancer(Bilkent University, 2020-09) Akbar, Muhammad WaqasBreast cancer (BC) is responsible for the highest mortality and morbidity out of all the cancers in women which is primarily due to both inter and intra-tumoral molecular heterogeneity. This heterogeneity arises from stemness, epithelial to mesenchymal transition and the type of treatment given to patients. These three biological processes are highly related with each other. Traditional therapy when given to breast cancer patients generally results in the transition of epithelial cells to mesenchymal phenotype. Because treatment targets primarily non-stem cells, it can leave stem cells alive which can later result in a relapse of cancer. In this study we aimed to identify such markers that could classify breast cancer patients into stem/mesenchymal or non-stem/epithelial like phenotypes, to determine how generalized the above stated hypotheses are. We developed a gene list of 15 genes we term as CSC/non-CSC gene list (CNCL) which classifies tumors into stemness and/or EMT based phenotypes and can also classify tumor cells based on their relative sensitivity to treatment with traditional therapeutics such as paclitaxel and doxorubicin. When classified into stem/mesenchymal (CS/M) and non-stem/epithelial (NS/E) phenotypes, we showed that Lapatinib and Midostaurin have a specific growth inhibitory effects on NS/E cells, and CS/M cells, respectively. Surprisingly the CNCL showed prognostic significance only for patients who were treated with paclitaxel in neoadjuvant setting, while it could not prognosticate most other BC cohorts. We argue that this is due to the dynamic plasticity of these tumors, as studied within the third aim of this thesis. Secondly, we aimed to identify chemotherapy biomarkers for paclitaxel, cisplatin and doxorubicin to stratify patients in groups that will or will not benefit from these drugs. Using biomarkers, we selected for this purpose, we performed linear regression analysis using breast cancer cell lines to generate cytotoxicity prediction models which can predict IC50 values for these drugs, based on the expression of two genes in each model. Two models were selected for doxorubicin and cisplatin, and three models were selected for paclitaxel. All models were validated both in silico and in vitro. Thirdly, we aimed to evaluate breast cancer plasticity that occurs upon treatment or when a tumor metastasizes. We noted that some breast tumors not only switch their clinical subtype but also change their molecular subtype upon treatment or metastasis. As breast cancer patient treatment in the routine practice is routed based on breast cancer subtype, it is very important to identify the subtype switches which can be critical for changes in treatment decisions. Additionally, we also identified metastatic biomarkers using large number of cohorts. Lastly, as CNCL genes did not show any prognostic importance in terms of both overall survival and metastasis free survival, we checked if the same is true for melanoma. We used Melanin A (MLANA) and Inhibin (INHBA) genes as the markers for invasive/proliferative, stem/non-stem and mesenchymal/epithelial phenotypes. High INHBA expression, which is epithelial, proliferative and non-stem phenotype biomarker, was associated with poor survival and high MLANA expression, which is mesenchymal, invasive and stem phenotype marker, was associated with good prognosis in melanoma patients. Therefore, these findings in melanoma supported our results in breast cancer.Item Open Access Renin angiotensin system genes are biomarkers for personalized treatment of acute myeloid leukemia with Doxorubicin as well as etoposide(Public Library of Science, 2020) Türk, S.; Türk, C.; Akbar, Muhammad Waqas; Küçükkaraduman, Barış; İşbilen, Murat; Demirkol-Canlı, S.; Malkan, Ü. Y.; Okay, M.; Uçar, G.; Sayınalp, N.; Haznedaroğlu, İ. C.; Güre, Ali OsmayDespite the availability of various treatment protocols, response to therapy in patients with Acute Myeloid Leukemia (AML) remains largely unpredictable. Transcriptomic profiling studies have thus far revealed the presence of molecular subtypes of AML that are not accounted for by standard clinical parameters or by routinely used biomarkers. Such molecular subtypes of AML are predicted to vary in response to chemotherapy or targeted therapy. The Renin-Angiotensin System (RAS) is an important group of proteins that play a critical role in regulating blood pressure, vascular resistance and fluid/electrolyte balance. RAS pathway genes are also known to be present locally in tissues such as the bone marrow, where they play an important role in leukemic hematopoiesis. In this study, we asked if the RAS genes could be utilized to predict drug responses in patients with AML. We show that the combined in silico analysis of up to five RAS genes can reliably predict sensitivity to Doxorubicin as well as Etoposide in AML. The same genes could also predict sensitivity to Doxorubicin when tested in vitro. Additionally, gene set enrichment analysis revealed enrichment of TNF-alpha and type-I IFN response genes among sensitive, and TGF-beta and fibronectin related genes in resistant cancer cells. However, this does not seem to reflect an epithelial to mesenchymal transition per se. We also identified that RAS genes can stratify patients with AML into subtypes with distinct prognosis. Together, our results demonstrate that genes present in RAS are biomarkers for drug sensitivity and the prognostication of AML.Item Open Access Simultaneous miRNA and mRNA transcriptome profiling of glioblastoma samples reveals a novel set of OncomiR candidates and their target genes(Elsevier, 2018) Güllüoğlu, Ş.; Tüysüz, E. C.; Şahin, M.; Kuşkucu, A.; Yaltırık, C. K.; Türe, U.; Küçükkaraduman, Barış; Akbar, Muhammad Waqas; Güre, Ali Osmay; Bayrak, Ö. F.; Dalan, A. B.Although glioblastomas are common, there remains a need to elucidate the underlying mechanisms behind their initiation and progression and identify molecular pathways for improving treatment. In this study, sixteen fresh-frozen glioblastoma samples and seven samples of healthy brain tissues were analyzed with miRNA and whole transcriptome microarray chips. Candidate miRNAs and mRNAs were selected to validate expression in fifty patient samples in total with the criteria of abundance, relevance and prediction scores. miRNA and target mRNA relationships were assessed by inhibiting selected miRNAs in glioblastoma cells. Functional tests have been conducted in order to see the effects of miRNAs on invasion, migration and apoptosis of GBM cells. Analyses were carried out to determine correlations between selected molecules and clinicopathological features. 1332 genes and 319 miRNAs were found to be dysregulated by the microarrays. The results were combined and analyzed with Transcriptome Analysis Console 3 software and the DAVID online database. Primary differential pathways included Ras, HIF-1, MAPK signaling and cell adhesion. OncomiR candidates 21-5p, 92b-3p, 182-5p and 339-5p for glioblastoma negatively correlated with notable mRNA targets both in tissues and in in vitro experiments. miR-21-5p and miR-339-5p significantly affected migration, invasion and apoptosis of GBM cells in vitro. Significant correlations with overall survival, tumor volume, recurrence and age at diagnosis were discovered. In this article we present valuable integrated microarray analysis of glioblastoma samples regarding miRNA and gene-expression levels. Notable biomarkers and miRNA-mRNA interactions have been identified, some of which correlated with clinicopathological features in our cohort.Item Open Access A stemness and EMT based gene expression signature identifies phenotypic plasticity and is a predictive but not prognostic biomarker for breast cancer(Ivyspring International Publisher, 2020) Akbar, Muhammad Waqas; Belder, Nevin; Demirkol-Canlı, Seçil; Küçükkaraduman, Barış; Türk, Can; Şahin, Özgür; Güre, Ali OsmayAims: Molecular heterogeneity of breast cancer results in variation in morphology, metastatic potential and response to therapy. We previously showed that breast cancer cell line sub-groups obtained by a clustering approach using highly variable genes overlapped almost completely with sub-groups generated by a drug cytotoxicity-profile based approach. Two distinct cell populations thus identified were CSC(cancer stem cell)-like and non-CSC-like. In this study we asked whether an mRNA based gene signature identifying these two cell types would explain variation in stemness, EMT, drug sensitivity, and prognosis in silico and in vitro. Main methods: In silico analyses were performed using publicly available cell line and patient tumor datasets. In vitro analyses of phenotypic plasticity and drug responsiveness were obtained using human breast cancer cell lines. Key findings: We find a novel gene list (CNCL) that can generate both categorical and continuous variables corresponding to the stemness/EMT (epithelial to mesenchymal transition) state of tumors. We are presenting a novel robust gene signature that unites previous observations related either to EMT or stemness in breast cancer. We show in silico, that this signature perfectly predicts behavior of tumor cells tested in vitro, and can reflect tumor plasticity. We thus demonstrate for the first time, that breast cancer subtypes are sensitive to either Lapatinib or Midostaurin. The same gene list is not capable of predicting prognosis in most cohorts, except for one that includes patients receiving neo-adjuvant taxene therapy. Significance: CNCL is a robust gene list that can identify both stemness and the EMT state of cell lines and tumors. It can be used to trace tumor cells during the course of phenotypic changes they undergo, that result in altered responses to therapeutic agents. The fact that such a list cannot be used to identify prognosis in most patient cohorts suggests that presence of factors other than stemness and EMT affect mortality.