Enhancing chemosensitivity in oral squamous cell carcinoma by lentivirus vector-mediated RNA interference targeting EGFR and MRP2

Abstract

Abstract. Oral cancer is the eighth most common type of cancer among men worldwide, with an age-standardized rate of 6.3 per 100,000, and is the fourth leading cause of cancer-associated mortality among men in Taiwan. Cisplatin and 5-fluorouracil (5-FU) are two of the most frequently utilized chemotherapy drugs for the treatment of oral cancer. Although oral cancer patients initially benefit from chemotherapy with these drugs, they may develop resistance to them, which worsens their prognosis and reduces survival rates. It has been reported that increased levels of epidermal growth factor receptor (EGFR) and multidrug resistance-associated protein 2 (MRP2) induce drug resistance in numerous types of human cancer. Therefore, the present study employed lentivirus vector-mediated RNA interference (RNAi) in order to target the genes encoding EGFR and MRP2 in the oral squamous cell carcinoma cell line OC2. It was observed that RNAi-mediated downregulation of EGFR or MRP2 increased the sensitivity to 5-FU and cisplatin in OC2 cells. Downregulation of EGFR resulted in significant suppression of OC2 tumor growth following 5-FU administration. However, simultaneous downregulation of the two genes did not further suppress the tumor growth, indicating that MRP2 does not have a significant role in the chemosensitivity of EGFR-downregulated cells to 5-FU. In contrast, downregulation of MRP2 was demonstrated to significantly enhance the therapeutic effects of cisplatin in EGFR-downregulated OC2 tumors. The observation that the expression of MRP2 was positively correlated with the level of cisplatin resistance in cells suggests that RNAi-mediated downregulation of MRP2 may be applicable as a therapeutic approach toward reversing MRP2-dependent cisplatin resistance in oral cancer. IntroductionOral cancer is the eighth most common type of cancer among men worldwide, with an age-standardized rate of 6.3 per 100,000 (1,2), and is the fourth leading cause of cancer-associated mortality among men in Taiwan (3). In addition, oral cancer has been ranked highest with respect to the rates of incidence and mortality among men aged 25-44 years in Taiwan since 2005 (3). Chemotherapy has been used as the primary treatment for patients exhibiting recurrent or metastatic cancers, including oral cancer (4). Of the various chemotherapy drugs available, cisplatin and 5-fluorouracil (5-FU) are the two most frequently utilized for the treatment of oral cancer (5). However, the efficacy of cancer chemotherapy is often limited by the development of drug resistance by the cancer cells in clinical practice (6).It has been demonstrated that multidrug resistance results largely from the expression of adenosine triphosphate-binding cassette (ABC) transporters with broad drug specificity (7-9). Multidrug resistance-associated protein 2 (MRP2), a member of the ABC transporter superfamily, has been observed in various tumors to confer resistance to a number of therapeutic drugs, including cisplatin (10-12). The levels of MRP2 messenger (m)RNA in certain hum...

Role Played by Paraoxonase-2 Enzyme in Cell Viability, Proliferation and Sensitivity to Chemotherapy of Oral Squamous Cell Carcinoma Cell Lines

“…OSCC cells, both those downregulating PON2 and controls, were treated with CDDP (0.1-2 µg/mL) or 5-FU (0.1-0.5 µg/mL) alone or with combinations of both compounds. Final drug concentration values, used in these series of experiments, were selected according to previous studies [48,49]. For each sample, sensitivity to drugs was evaluated through MTT assay and represented as percentage of decrease in cell viability.…”

“…A pulsed-selection strategy was adopted, where cells were treated with chemotherapeutic agent and then allowed to recover in a drug-free medium [48,53]. To this purpose, HOC621 cells were seeded onto a 24-well plate at 20% confluence.…”

The role of non‐coding RNAs in drug resistance of oral squamous cell carcinoma and therapeutic potential

“…EGFR inhibitors sensitized OSCC cells to 5‐FU and CDDP. It has been proposed that inhibition of the EGFR signaling pathway may serve as a reasonable strategy for the treatment of drug‐resistant OSCC patients [ 178 , 179 ]. Furthermore, Li et al.…”

Circulating Natural Autoantibodies to HER2-Derived Peptides Performed Antitumor Effects on Oral Squamous Cell Carcinoma

“…About 20-30% OSCC patients experienced relapse regardless of treatment; the prognosis of OSCC is rather poor and the overall 5-years survival rate is roughly 50% across the globe (Singhvi et al, 2017;Zhao et al, 2020;Sarkar et al, 2021). Current therapies available for treatments of OSCC include surgical resection, radiotherapy, chemotherapy, immunotherapy, gene therapy as well as combination of several therapies (Gau et al, 2019;Gigliotti et al, 2019;Yang et al, 2020); however, these treatments may result in serious problems such as complications, oral cavity disorders and multi-drug resistance (MDR) to chemotherapy (Chen et al, 2016).…”