Evaluation of the efficacy and treatment sequence of paclitaxel and gemcitabine-loaded microparticles in a serous-like endometrial cancer cell line: a novel treatment strategy

Abstract

<h3>Objectives:</h3> Uterine serous carcinoma (USC) presents a clinical challenge due its propensity to present at advanced stages, high recurrence rate and development of chemoresistance. The majority of patients with advanced disease will progress or recur following first-line platinum-based chemotherapy. As a result, new treatment strategies are urgently needed. Poly (lactic-co-glycolic acid)-based (PLGA) microparticles (MP) are a promising tool for delivery of chemotherapy due to prolonged drug elution over a period of several weeks, offering the benefit of sustained anti-cancer activity in the target tissue while limiting systemic toxicity. This is an attractive treatment strategy for USC, which can be accessed vaginally, allowing for the delivery of drug-loaded MP directly to the tumor. Previous work demonstrates paclitaxel and gemcitabine can be successfully loaded to PLGA-MP for drug delivery. <h3>Methods:</h3> The human endometrial cancer (EC) cell line KLE, representing a poorly differentiated serous-like EC was obtained from ATCC. Cells were treated with paclitaxel-loaded MP only (PMP), gemcitabine-loaded MP only (GMP), PMP-GMP sequence (PG), GMP-PMP sequence (GP) and PMP-GMP delivered concurrently (C). Blank MP (BMP) were used as control for each treatment. Cells were then collected at 6-days post-treatment for isolation of protein and assessment of cytotoxicity by cell viability assay. Protein lysates were analyzed for expression of multiagent chemoresistance protein AXL and paclitaxel resistance protein beta III tubulin (TUBB3) and apoptotic protein cleaved-PARP by Western Blot. <h3>Results:</h3> We observed morphologic changes and a decrease in cell density in all treatment regimens versus controls. These changes were most marked in the two-drug combination regimens. A significant increase in cleaved-PARP was observed in all treatments compared to controls. Chemoresistance proteins AXL and TUBB3 were not expressed in controls. AXL expression was increased in all treatment regimens. TUBB3 expression was significantly greater in PMP and GP regimens compared to PG (p=0.05). All treatment regimens were associated with a significantly decrease in cell viability versus controls (p<0.001). GMP containing regimens produced a greater decrease in cell viability compared to single agent paclitaxel. C treatment produced a significantly greater decrease in cell viability compared to all other regimens (p<0.001). <h3>Conclusions:</h3> PMP and GMP demonstrated significant cytotoxicity in a serous-like EC cell line. Concurrent PMP-GMP administration elicited the greatest decrease in cell viability. TUBB3 expression was markedly less when cells received PG, indicating the sequence of paclitaxel followed by gemcitabine may counteract paclitaxel resistance observed with single agent paclitaxel and alternate sequencing. Chemotherapy delivered via MP is an attractive treatment strategy for advanced and recurrent USC. Future <i>in vivo</i> studies are needed to validate this new treatment approach.