A Novel Synthetic Dihydroindeno[1,2-b] Indole Derivative (LS-2-3j) Reverses ABCB1- and ABCG2-Mediated Multidrug Resistance in Cancer Cells

Formulation, Characterization and Cytotoxicity Effects of Novel Thymoquinone-PLGA-PF68 Nanoparticles

Thymoquinone has anti-cancer properties. However, its application for clinical use is limited due to its volatile characteristics. The current study aims to develop a polymeric nanoformulation with PLGA-PEG and Pluronics F68 as encapsulants to conserve thymoquinone’s (TQ) biological activity before reaching the target sites. Synthesis of nanoparticles was successfully completed by encapsulating TQ with polymeric poly (D, L-lactide-co-glycolide)-block-poly (ethylene glycol) and Pluronics F68 (TQ-PLGA-PF68) using an emulsion–solvent evaporation technique. The size and encapsulation efficiency of TQ-PLGA-PF68 nanoparticles were 76.92 ± 27.38 nm and 94%, respectively. TQ released from these encapsulants showed a biphasic released pattern. Cytotoxicity activity showed that tamoxifen-resistant (TamR) MCF-7 breast cancer cells required a higher concentration of TQ-PLGA-PF68 nanoparticles than the parental MCF-7 cells to achieve IC₅₀ (p < 0.05). The other two resistant subtypes (TamR UACC732 inflammatory breast carcinoma and paclitaxel-resistant (PacR) MDA-MB 231 triple-negative breast cell line) required a lower concentration of TQ-PLGA-PF68 nanoparticles compared to their respective parental cell lines (p < 0.05). These findings suggest that TQ encapsulation with PLGA-PEG and Pluronics F68 is a promising anti-cancer agent in mitigating breast cancer resistance to chemotherapeutics. In future studies, the anti-cancer activity of TQ-PLGA-PF68 with the standard chemotherapeutic drugs used for breast cancer treatment is recommended.

Current scenario of indole derivatives with potential anti-drug-resistant cancer activity

Cancer chemotherapy is frequently hampered by drug resistance, so the resistance to anticancer agents represents one of the major obstacles for the effective cancer treatment. Indole derivatives have the potential to act on diverse targets in cancer cells and exhibit promising activity against drug-resistant cancers. Moreover, some indole-containing compounds such as Semaxanib, Sunitinib, Vinorelbine, and Vinblastine have already been applied in clinics for various kinds of cancer even drug-resistant cancer therapy. Thus, indole derivatives are one of significant resources for the development of novel anti-drug-resistant cancer agents. This review focuses on the recent development of indole derivatives with potential therapeutic application for drug-resistant cancers, and the mechanisms of action, the critical aspects of design as well as structure-activity relationships, covering articles published from 2010 to 2020.

Advanced oxidation protein products upregulate efflux transporter expression and activity through activation of the Nrf-2-mediated signaling pathway in vitro and in vivo

Clinical and benchtop studies suggest that chronic kidney disease (CKD) alters both renal and nonrenal clearance of drugs. Although studies have documented that the accumulating uremic toxins in the body under CKD conditions are humoral factors that alter the expression and/or activity of drug transporters, the specific process is poorly understood. In this study, we found that advanced oxidation protein products (AOPPs), which are a modified protein uremic toxin, could upregulate efflux transporters, including P-glycoprotein (ABCB1), multi-drug resistance-associated protein 2 (ABCC2) and breast cancer resistance protein (ABCG2) expression in CKD rat models and in HepG2 cells. Our research shows that renal function decline was associated with the accumulation of AOPPs in serum and the upregulation of efflux transporters in the liver in two rat models of CKD. In HepG2 cells, AOPPs significantly increased the expression of efflux transporters in a dose- and time-dependent manner and upregulated the mRNA expression, protein expression and activity of efflux transporters, but bovine serum albumin (BSA), a synthetic precursor of AOPPs, had no effect. This effect correlated with AOPPs activation of the nuclear factor E2-related factor 2 (Nrf-2)-mediated signaling pathway. Further investigation of the regulation of Nrf-2 by AOPPs revealed that ML385 and siNrf-2 abolished the upregulatory effects of AOPPs. These findings suggest that AOPPs upregulate ABCB1, ABCG2 and ABCC2 through Nrf-2 signaling pathways. Protein uremic toxins, such as AOPPs, may modify the nonrenal clearance of drugs in patients with CKD through effects on drug transporters.

Inhibitors of Human ABCG2: From Technical Background to Recent Updates With Clinical Implications

The ATP-binding cassette transporter G2 (ABCG2; also known as breast cancer resistance protein, BCRP) has been suggested to be involved in clinical multidrug resistance (MDR) in cancer like other ABC transporters such as ABCB1 (P-glycoprotein). As an efflux pump exhibiting a broad substrate specificity localized on cellular plasma membrane, ABCG2 excretes a variety of endogenous and exogenous substrates including chemotherapeutic agents, such as mitoxantrone and several tyrosine kinase inhibitors. Moreover, in the normal tissues, ABCG2 is expressed on the apical membranes and plays a pivotal role in tissue protection against various xenobiotics. For this reason, ABCG2 is recognized to be an important determinant of the pharmacokinetic characteristics of its substrate drugs. Although the clinical relevance of reversing the ABCG2-mediated MDR has been inconclusive, an appropriate modulation of ABCG2 function during chemotherapy should logically enhance the efficacy of anti-cancer agents by overcoming the MDR phenotype and/or improving their pharmacokinetics. To confirm this possibility, considerable efforts have been devoted to developing ABCG2 inhibitors, although there is no clinically available substance for this purpose. As a clue for addressing this issue, this mini-review provides integrated information covering the technical backgrounds necessary to evaluate the ABCG2 inhibitory effects on the target compounds and a current update on the ABCG2 inhibitors. This essentially includes our recent findings, as we serendipitously identified febuxostat, a well-used agent for hyperuricemia as a strong ABCG2 inhibitor, that possesses some promising potentials. We hope that an overview described here will add value to further studies involving in the multidrug transporters.