Therapy-relevant aberrant expression of MRP3 and BCRP mRNA in TCC-/SCC-bladder cancer tissue of untreated patients

Overcoming Cancer Multi-drug Resistance (MDR): Reasons, mechanisms, nanotherapeutic solutions, and challenges

Multi-drug resistance (MDR) in cancer cells, either intrinsic or acquired through various mechanisms, significantly hinders the therapeutic efficacy of drugs. Typically, the reduced therapeutic performance of various drugs is predominantly due to the inherent over expression of ATP-binding cassette (ABC) transporter proteins on the cell membrane, resulting in the deprived uptake of drugs, augmenting drug detoxification, and DNA repair. In addition to various physiological abnormalities and extensive blood flow, MDR cancer phenotypes exhibit improved apoptotic threshold and drug efflux efficiency. These severe consequences have substantially directed researchers in the fabrication of various advanced therapeutic strategies, such as co-delivery of drugs along with various generations of MDR inhibitors, augmented dosage regimens and frequency of administration, as well as combinatorial treatment options, among others. In this review, we emphasize different reasons and mechanisms responsible for MDR in cancer, including but not limited to the known drug efflux mechanisms mediated by permeability glycoprotein (P-gp) and other pumps, reduced drug uptake, altered DNA repair, and drug targets, among others. Further, an emphasis on specific cancers that share pathogenesis in executing MDR and effluxed drugs in common is provided. Then, the aspects related to various nanomaterials-based supramolecular programmable designs (organic- and inorganic-based materials), as well as physical approaches (light- and ultrasound-based therapies), are discussed, highlighting the unsolved issues and future advancements. Finally, we summarize the review with interesting perspectives and future trends, exploring further opportunities to overcome MDR.

Polymorphic renal transporters and cisplatin's toxicity in urinary bladder cancer patients: current perspectives and future directions

Urinary bladder cancer (UBC) holds a potentially profound social burden and affects over 573,278 new cases annually. The disease's primary risk factors include occupational tobacco smoke exposure and inherited genetic susceptibility. Over the past 30 years, a number of treatment modalities have emerged, including cisplatin, a platinum molecule that has demonstrated effectiveness against UBC. Nevertheless, it has severe dose-limiting side effects, such as nephrotoxicity, among others. Since intracellular accumulation of platinum anticancer drugs is necessary for cytotoxicity, decreased uptake or enhanced efflux are the root causes of platinum resistance and response failure. Evidence suggests that genetic variations in any transporter involved in the entry or efflux of platinum drugs alter their kinetics and, to a significant extent, determine patients' responses to them. This review aims to consolidate and describe the major transporters and their polymorphic variants in relation to cisplatin-induced toxicities and resistance in UBC patients. We concluded that the efflux transporters ABCB1, ABCC2, SLC25A21, ATP7A, and the uptake transporter OCT2, as well as the organic anion uptake transporters OAT1 and OAT2, are linked to cisplatin accumulation, toxicity, and resistance in urinary bladder cancer patients. While suppressing the CTR1 gene's expression reduced cisplatin-induced nephrotoxicity and ototoxicity, inhibiting the expression of the MATE1 and MATE2-K genes has been shown to increase cisplatin's nephrotoxicity and resistance. The roles of ABCC5, ABCA8, ABCC10, ABCB10, ABCG1, ATP7B, ABCG2, and mitochondrial SLC25A10 in platinum-receiving urinary bladder cancer patients should be the subject of further investigation.

Epigallocatechin-3-gallate promotes apoptosis and reversal of multidrug resistance in esophageal cancer cells

Evidence for demonstrating the role of the green tea component epigallocatechin-3-gallate (EGCG) in esophageal squamous cell carcinoma cells is limited. In this study, we investigated apoptosis induced by EGCG and the underlying molecular mechanisms in human esophageal squamous cell carcinoma cells. The growth-inhibitory effects of EGCG on esophageal cancer cell (Eca109 and Ec9706) were detected by MTT. Using flow cytometry, we determined the cellular apoptosis, bcl-2, bax and caspase-3 protein expression in Eca109 and Ec9706 cells following treatment with EGCG for 24h. After treatment of Eca109/ABCG2 (an esophageal cancer multidrug resistance cell line) cells with adriamycin (ADM) combined with EGCG for 24h, the cellular apoptosis, mitochondrial membrane potential, ADM concentration in cells and ABCG2 protein expression were detected by flow cytometry. EGCG inhibited the growth of Eca109 and Ec9706 cells in a dose- and time- dependent manner. EGCG induced apoptosis, decreased the bcl-2 protein expression and increased the expression of bax and caspase-3 protein. The rate of apoptosis and ADM concentration in the Eca109/ABCG2 cells following treatment with ADM and EGCG were higher than that with ADM treatment alone, although the mitochondrial membrane potential was significantly lower (P<0.01). EGCG reduced the ABCG2 expression of Eca109/ABCG2 cells. Our data indicated that EGCG inhibited cell growth and induced esophageal cancer cell apoptosis. It reduced the bcl-2 protein expression and increased the bax and caspase-3 protein expression. EGCG reversed multi-drug resistance by reducing ABCG2 expression and increasing the anticancer drug concentration in cancer cells.