Defective hCNT1 transport contributes to gemcitabine chemoresistance in ovarian cancer subtypes: Overcoming transport defects using a nanoparticle approach

Abstract

Nucleoside analogs are used as chemotherapeutic options for the treatment of platinum-resistant ovarian cancers. Human concentrative nucleoside transporter 1 (hCNT1) is implicated in sensitizing solid tumors to nucleoside analogs although its role in determining drug efficacy in ovarian cancers remains unclear. Here we examined the functional expression of hCNT1 and compared its contributions towards gemcitabine efficacy in histological subtypes of ovarian cancer. Radioactivity analysis identified hCNT1-mediated 3H-gemcitabine transport in ovarian cancer cells to be significantly reduced compared with that of normal ovarian surface epithelial cells. Biochemical and immunocytochemical analysis identified that unlike normal ovarian cells which expressed high levels of hCNT1 at the apical cell surface, the transporter was either diminished in expression and/or mislocalized in cell lines of various subtypes of ovarian cancer. Retroviral expression of hCNT1 selectively rescued gemcitabine transport in cell lines representing serous, teratocarcinoma, and endometrioid subtypes, but not clear cell carcinoma (CCC). In addition, exogenous hCNT1 predominantly accumulated in intracytoplasmic vesicles in CCC suggesting defective cellular trafficking of hCNT1 as a contributing factor to transport deficiency. Despite diminution of hCNT1 transport in the majority of ovarian cancers and apparent trafficking defects with CCC, the chemotherapeutic efficacy of gemcitabine was broadly enhanced in all subtypes when delivered via engineered nanoparticles (NPs). Additionally, by bypassing the transport requirement, the delivery of a gemcitabine-cisplatin combination in NP formulation increased their synergistic interactions. These findings uncover hCNT1 as a putative determinant for nucleoside analog chemoresistance in ovarian cancer and may help rationalize drug selection and delivery strategies for various histological subtypes of ovarian cancer.

The Application of Biomaterials in the Treatment of Platinum‐Resistant Ovarian Cancer

“…Gemcitabine is a nucleoside analogue that triggers apoptosis by replacing cytidine during DNA replication . This drug is associated with several limitations, including poor pharmacokinetics and rapid metabolic deactivation of gemcitabine . Co‐delivery via NCP made the effects of each drug more efficient by allowing them to retain and accumulate the drug in the tumor, resulted in tumor regression.…”

Overcoming tumor cell chemoresistance using nanoparticles: lysosomes are beneficial for (stearoyl) gemcitabine-incorporated solid lipid nanoparticles

“…For example, we have data showing that our previously developed stearoyl gemcitabine solid lipid nanoparticles (ie, 4-(N)-GemC18-SLNs) enter tumor cells by clathrin-mediated endocytosis. 174 Hung et al showed that a nanoparticle formulation of gemcitabine has significantly smaller IC 50 values, compared to free gemcitabine, in ovarian cancer cells that express low levels of hCNT1, 175 indicating that the nanoparticle formulation can bypass nucleoside transporter defects.…”

“…The gemcitabine-PLGA-b-PEG-OH nanoparticles effectively delivered gemcitabine into hCNT1-decreased ES-2 and TOV-21G tumor cells and were significantly more cytotoxic to those cells than free gemcitabine. 175 Papa et al reported gemcitabine-loaded PLGA nanoparticles (PLGem) and evaluated their cytotoxicity to aggressive human Panc-1 cells, which are well-known to exhibit gemcitabine resistance. 194 The PLGem was significantly more cytotoxic than free gemcitabine to Panc-1 cells.…”

Nanoscale Coordination Polymers Codeliver Carboplatin and Gemcitabine for Highly Effective Treatment of Platinum-Resistant Ovarian Cancer

“…18–21 However, gemcitabine is often limited by its poor pharmacokinetics and rapid metabolic deactivation. 22–24 Furthermore, the combination with Pt often enhances gemcitabine’s hematological toxicity. 25,26 Therefore, there is an urgent need to develop a delivery system for combination drugs that can overcome the limitations imposed by free platinum drugs and gemcitabine.…”