Contribution of MicroRNAs in Chemoresistance to Cisplatin in the Top Five Deadliest Cancer: An Updated Review

Dual‑regulated oncolytic adenovirus carrying ERCC1‑siRNA gene possesses potent antitumor effect on ovarian cancer cells

Ovarian cancer is a multifactorial and deadly disease. Despite significant advancements in ovarian cancer therapy, its incidence is on the rise and the molecular mechanisms underlying ovarian cancer invasiveness, metastasis and drug resistance remain largely elusive, resulting in poor prognosis. Oncolytic viruses armed with therapeutic transgenes of interest offer an attractive alternative to chemical drugs, which often face innate and acquired drug resistance. The present study constructed a novel oncolytic adenovirus carrying ERCC1 short interfering (si)RNA, regulated by hTERT and HIF promoters, termed Ad‑siERCC1. The findings demonstrated that this oncolytic adenovirus effectively inhibits the proliferation, migration and invasion of ovarian cancer cells. Furthermore, the downregulation of ERCC1 expression by siRNA ameliorates drug resistance to cisplatin (DDP) chemotherapy. It was found that Ad‑siERCC1 blocks the cell cycle in the G1 phase and enhances apoptosis through the PI3K/AKT‑caspase‑3 signaling pathways in SKOV3 cells. The results of the present study highlighted the critical effect of oncolytic virus Ad‑siERCC1 in inhibiting the survival of ovarian cancer cells and increasing chemotherapy sensitivity to DDP. These findings underscore the potent antitumor effect of Ad‑siERCC1 on ovarian cancers in vivo.

Role of Epigenetics for the Efficacy of Cisplatin

The clinical utility of the chemotherapeutic agent cisplatin is restricted by cancer drug resistance, which is either intrinsic to the tumor or acquired during therapy. Epigenetics is increasingly recognized as a factor contributing to cisplatin resistance and hence influences drug efficacy and clinical outcomes. In particular, epigenetics regulates gene expression without changing the DNA sequence. Common types of epigenetic modifications linked to chemoresistance are DNA methylation, histone modification, and non-coding RNAs. This review provides an overview of the current findings of various epigenetic modifications related to cisplatin efficacy in cell lines in vitro and in clinical tumor samples. Furthermore, it discusses whether epigenetic alterations might be used as predictors of the platinum agent response in order to prevent avoidable side effects in patients with resistant malignancies. In addition, epigenetic targeting therapies are described as a possible strategy to render cancer cells more susceptible to platinum drugs.

Tumorigenic effects of human mesenchymal stromal cells and fibroblasts on bladder cancer cells

Background

Patients with muscle-invasive bladder cancer face a poor prognosis due to rapid disease progression and chemoresistance. Thus, there is an urgent need for a new therapeutic treatment. The tumor microenvironment (TME) has crucial roles in tumor development, growth, progression, and therapy resistance. TME cells may also survive standard treatment of care and fire up disease recurrence. However, whether specific TME components have tumor-promoting or tumor-inhibitory properties depends on cell type and cancer entity. Thus, a deeper understanding of the interaction mechanisms between the TME and cancer cells is needed to develop new cancer treatment approaches that overcome therapy resistance. Little is known about the function and interaction between mesenchymal stromal cells (MSC) or fibroblasts (FB) as TME components and bladder cancer cells.

Methods

We investigated the functional impact of conditioned media (CM) from primary cultures of different donors of MSC or FB on urothelial carcinoma cell lines (UCC) representing advanced disease stages, namely, BFTC-905, VMCUB-1, and UMUC-3. Underlying mechanisms were identified by RNA sequencing and protein analyses of cancer cells and of conditioned media by oncoarrays.

Results

Both FB- and MSC-CM had tumor-promoting effects on UCC. In some experiments, the impact of MSC-CM was more pronounced. CM augmented the aggressive phenotype of UCC, particularly of those with epithelial phenotype. Proliferation and migratory and invasive capacity were significantly increased; cisplatin sensitivity was reduced. RNA sequencing identified underlying mechanisms and molecules contributing to the observed phenotype changes. NRF2 and NF-κB signaling was affected, contributing to improved cisplatin detoxification. Likewise, interferon type I signaling was downregulated and regulators of epithelial mesenchymal transition (EMT) were increased. Altered protein abundance of CXCR4, hyaluronan receptor CD44, or TGFβ-signaling was induced by CM in cancer cells and may contribute to phenotypical changes. CM contained high levels of CCL2/MCP-1, MMPs, and interleukins which are well known for their impact on other cancer entities.

Conclusions

The CM of two different TME components had overlapping tumor-promoting effects and increased chemoresistance. We identified underlying mechanisms and molecules contributing to the aggressiveness of bladder cancer cells. These need to be further investigated for targeting the TME to improve cancer therapy.

Tumor Cells Transmit Drug Resistance via Cisplatin-Induced Extracellular Vesicles

Cisplatin is a first-line clinical agent used for treating solid tumors. Cisplatin damages the DNA of tumor cells and induces the production of high levels of reactive oxygen species to achieve tumor killing. Tumor cells have evolved several ways to tolerate this damage. Extracellular vesicles (EVs) are an important mode of information transfer in tumor cells. EVs can be substantially activated under cisplatin treatment and mediate different responses of tumor cells under cisplatin treatment depending on their different cargoes. However, the mechanism of action of tumor-cell-derived EVs under cisplatin treatment and their potential cargoes are still unclear. This review considers recent advances in cisplatin-induced release of EVs from tumor cells, with the expectation of providing a new understanding of the mechanisms of cisplatin treatment and drug resistance, as well as strategies for the combined use of cisplatin and other drugs.

MicroRNAs as master regulators of FOXO transcription factors in cancer management

MicroRNAs are critical regulators of the plethora of genes, including FOXO "forkhead" dependent transcription factors, which are bonafide tumour suppressors. The FOXO family members modulate a hub of cellular processes like apoptosis, cell cycle arrest, differentiation, ROS detoxification, and longevity. Aberrant expression of FOXOs in human cancers has been observed due to their down-regulation by diverse microRNAs, which are predominantly involved in tumour initiation, chemo-resistance and tumour progression. Chemo-resistance is a major obstacle in cancer treatment. Over 90% of casualties in cancer patients are reportedly associated with chemo-resistance. Here, we have primarily discussed the structure, functions of FOXO and also their post-translational modifications which influence the activities of these FOXO family members. Further, we have addressed the role of microRNAs in carcinogenesis by regulating the FOXOs at post-transcriptional level. Therefore, microRNAs-FOXO axis can be exploited as a novel cancer therapy. The administration of microRNA-based cancer therapy is likely to be beneficial to curb chemo-resistance in cancers.

Regulation of cisplatin resistance in bladder cancer by epigenetic mechanisms

Bladder cancer is one of the most common malignancies in the world. Cisplatin is one of the most potent and widely used anticancer drugs and has been employed in several malignancies. Cisplatin-based combination chemotherapies have become important adjuvant therapies for bladder cancer patients. Cisplatin-based treatment often results in the development of chemoresistance, leading to therapeutic failure and limiting its application and effectiveness in bladder cancer. To develop improved and more effective cancer therapy, research has been conducted to elucidate the underlying mechanism of cisplatin resistance. Epigenetic modifications have been demonstrated involved in drug resistance to chemotherapy, and epigenetic biomarkers, such as urine tumor DNA methylation assay, have been applied in patients screening or monitoring. Here, we provide a systematic description of epigenetic mechanisms, including DNA methylation, noncoding RNA regulation, m6A modification and posttranslational modifications, related to cisplatin resistance in bladder cancer.