Presence Of Anticancer Agents Research Articles

Abstract B037: Characterizing and targeting polyaneuploid/polyploid giant cancer cells (PACCs/PGCCs)

Abstract Polyaneuploid/polyploid giant cancer cells (PACCs/PGCCs) are common in tumors and have been tightly linked with tumor heterogeneity, resistance to cancer therapy, tumor relapse, metastasis, malignancy, immunosuppression, modulation of the tumor microenvironment and cancer stem cells. The abundance of PACCs/PGCCs is markedly higher in high-grade malignant tumors than in low-grade tumors, in the metastatic foci than in the primary tumor, and in relapsing tumors post-chemotherapy than in tumors before therapy. Immunosuppressive proteins including programmed death-ligand 1 (PD-L1) were also found to be overexpressed in these cells. Such cells are known to escape from cytotoxicity induced by major anti-cancer agents including taxanes, vinca alkaloids and platinum-based chemotherapies. Therefore, they are responsible of contributing to a microenvironment advantageous for tumor growth and survival. However, the molecular mechanisms that cause these cells to form were not yet known. PACCs/PGCCs can repopulate in vitro as they generate tumors when inoculated into mice. Their daughter cells acquire a mesenchymal phenotype, which is a key transformation for cancer development, progression and metastasis. Emerging evidence has demonstrated PACCs/PGCCs arise in lung cancer, cervical carcinoma, ovarian cancer, prostate cancer, glioblastoma, colorectal cancer and breast cancer. Therefore, revealing the molecular events that cause PACCs/PGCCs to form could lead to clinically relevant approaches for treating recurrent and metastatic disease. With our studies, we discovered that Aurora kinases and Cyclin-dependent kinases 4/6 (CDK4/6) were two separate synergistic determinants of distinct switches from the proliferative cell cycle to polyploid growth state in lung cancer cell lines. When Aurora kinases are inhibited together, cancer cells uniformly grow into multinucleated PACCs/PGCCs whereas inactivation of CDK4/6 forms mononucleated PACCs/PGCCs. These cells adopt an endoreplication in which the genome replicates, mitosis is omitted and cells grow in size. Consequently, such cells continue to safely grow in the presence of anti-cancer agents. These PGCCs can reenter the proliferative cell cycle and grow in cell number when the treatment is terminated. Based upon our results, we were funded to find chemical inhibitors to target PACCs/PGCCs. We have conducted a high-throughput screen of 332,500 chemicals of the UT Southwestern chemical library to identify those that were toxic to our representative cell line model, but not to cells with normal ploidy, including immortalized normal human bronchial epithelial cells (HBECs). Currently, in our research program, we have two major projects, which includes: (1) A complete biological and mechanistic characterization of PACCs/PGCCs in cancer initiation, progression, metastasis and drug resistance, and (2) development of inhibitors to target PACCs/PGCCs as drug candidates for cancer therapies. To the best of our knowledge, ours are the first studies to describe the responsible genes involved in the formation of PACCs/PGCCs. Citation Format: Vural Tagal, Uttam K. Tambar, Michael G. Roth, John D. Minna. Characterizing and targeting polyaneuploid/polyploid giant cancer cells (PACCs/PGCCs) [abstract]. In: Proceedings of the AACR Special Conference on the Evolutionary Dynamics in Carcinogenesis and Response to Therapy; 2022 Mar 14-17. Philadelphia (PA): AACR; Cancer Res 2022;82(10 Suppl):Abstract nr B037.

Abstract 3767: Transcriptional and proteomic profiling of drug-tolerant cancer cell subpopulations using colonies that emerge in the presence of anticancer agents

Abstract Background: Cancer relapse after curative treatment is thought to originate from drug-tolerant cancer cell subpopulations. To isolate and characterize the drug-tolerant cell subpopulations, we collected individual colonies that emerged in the presence of anticancer drugs and performed proteomic profiling using reverse-phase protein arrays (RPPAs). Materials and Methods: Cancer cells (HCT116, HeLa, HT29, MCF7, and MKN45) were sparsely disseminated (10-100 cells/cm2) into the presence of anticancer drugs (cisplatin, docetaxel, gefitinib, and sorafenib) of six serially diluted concentrations on the basis of 50% colony inhibitory concentration (CI50) for each drug. A total of 2,400 individual colony lysates (20 colony lysates per drug concentration) were printed on glass slides using a dedicated microarrayer followed by immunochemical detection of 44 functionally-diverse proteins. A transcriptional profiling followed by gene ontology (GO) analysis was also performed. Results: CI50 of cisplatin and docetaxel were >10 times lower than the 50% growth inhibitory concentration (GI50) in all cell lines. This indicates that colony formation is functionally different from exponential cell growth, and drug-tolerant colony initiation can be suppressed by traditional anticancer drugs with very low doses. Colony lysate arrays revealed that the colonies expressing stemness, pluripotent, and mesenchymal markers tended to show low levels of epithelial proteins. However, individual protein expression levels were not well associated with drug concentrations, suggesting that these protein phenotypes of colonies were not necessarily induced by anticancer drugs. Instead, they may have emerged spontaneously. To identify molecular fractions important to drug-tolerant phenotypes, we screened compounds inhibiting chromatin formation, transcription, and protein biosynthesis. A transcriptional inhibitor eliminated drug-tolerant colonies within a short (four-hour) temporal treatment, suggesting that putative drug-tolerance inducing factors were controlled at the transcriptional level. Analysis of cDNA microarray using drug-free and cisplatin-resistant colonies followed by GO analysis revealed that most expressed genes in cisplatin-resistant colonies were specifically associated with embryonic development. Conclusion: These findings suggest that the regulatory system at the protein level is unlikely to be directly associated with drug-tolerant colony formation. Instead, transcriptional regulation appears to play a crucial role in forming drug-tolerant colonies. Citation Format: Kohei Kume, Satoshi Nishizuka, Miyuki Ikeda, Sawako Miura, Fumitaka Endo, Katagiri Hirokatsu, Kaoru Ishida, Kei Sato, Chihaya Maesawa, Go Wakabayashi. Transcriptional and proteomic profiling of drug-tolerant cancer cell subpopulations using colonies that emerge in the presence of anticancer agents. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3767. doi:10.1158/1538-7445.AM2014-3767

The inhibition of constitutive androstane receptor-mediated pathway enhances the effects of anticancer agents in ovarian cancer cells

BackgroundOvarian cancer is commonly treated with anticancer agents; however, many tumors become resistant. Resistance is regulated, in part, by P-glycoprotein, which is encoded by the gene multiple drug resistance 1 (MDR1) and functions as a transmembrane efflux pump for the elimination of anticancer agents. Constitutive androstane receptor (CAR) is a nuclear receptor that regulates drug metabolism through control of MDR1 and other genes. PurposeWe examined whether the inhibition of CAR-mediated pathway could influence the cytotoxicity of three anticancer drugs, cisplatin, paclitaxel, and arsenic trioxide, in ovarian cancer cells. ResultsWe observed that the cell proliferation of several ovarian cell lines expressing CAR significantly increased when CITCO was combined with anticancer agents compared with any anticancer agent alone. The up-regulation of MDR1 and UGT1A1 by anticancer agents was further enhanced in the presence of CITCO. We confirmed that combining CITCO with anticancer agents induced significantly lower levels of apoptosis than those achieved with any single anticancer drug. CAR down-regulation by RNA interference caused a significant increase in cell growth inhibition and enhancement of apoptosis in the presence of anticancer agents. Combination of CITCO with any anticancer agents significantly enhanced CAR-mediated transcription compared with any anticancer agents alone and CAR down-regulation completely inhibited the transcription in the presence of CITCO and/or anticancer agents. ConclusionInhibition of CAR pathway could be a novel therapeutic approach for the augmentation of sensitivity to anticancer agents, or to overcome resistance, in the treatment of ovarian cancer.

Drug resistance and the microenvironment: nature and nurture.

Drug resistance remains a major obstacle to the successful use of chemotherapeutic drugs for cancer therapy. It is well documented that cancer cells can adapt to the presence of chemotherapeutic agents through mutations or expression changes of key genes that control drug metabolism or response to damage. In addition, it is becoming increasingly apparent that the tumor microenvironment can have an important impact on the success of chemotherapy. Indeed, cell-cell and cell-matrix interactions can influence the cancer cells sensitivity to apoptosis and affect drug resistance. A model is proposed in which the tumor cells may actively reorganize their environment to maximize their survival in the presence of anticancer agents.

The direct activation of human multidrug resistance gene (MDR1) by anticancer agents

Enhanced expression of a multidrug-resistance gene (MDR1) is observed in some cancer patient, but any regulatory mechanism of MDR1 gene expression in this phenomenon is not yet known. In this study, the regulation of MDR1 gene was analysed by transient expression assays in the presence of anticancer agents. We found that MDR1 promoter could be activated directly on the addition of anticancer agents including vincristine, daunomycin, adriamycin and colchicine. The results suggest that the level of MDR1 mRNA expression is associated with previous chemotherapy, including drugs that select the multidrug resistance phenotype.