Rosmarinic acid enhances 5-fluorouracil sensitivity in HGC27 gastric cancer cells

Abstract

Gastric cancer remains a prominent contributor to global cancer-related mortality, even though major advances in treatment have been made. Its high mortality rate is associated with resistance to chemotherapy and the limited clinical efficacy of commonly used drugs, such as 5-fluorouracil (5-FU). Rosmarinic acid (RA), a polyphenol found in high concentrations in Lamiaceae species, has antioxidant and anti-cancer properties. However, its potential to improve the effectiveness of 5-FU in poorly differentiated gastric cancer has not been adequately investigated. The objective of this study was to assess the cytotoxic effects, apoptosis-inducing potential, and underlying molecular alterations of RA and 5-FU, administered individually or in combination, in HGC27 gastric cancer cells. The effects on cell viability were assessed using the MTT assay, and apoptotic cell death was analyzed by Annexin V-FITC flow cytometry. The expression of the genes associated with apoptosis, stemness, and proliferation was evaluated by qRT-PCR. The IC25 and IC50 values of 5-FU were approximately 1.25 µM and 3.62 µM, respectively, whereas those of RA were approximately 23.2 µM and 50.7 µM, respectively. Both RA and 5-FU reduced cell viability in a concentration-dependent fashion and induced apoptosis at their respective IC₅₀ concentrations. Specifically, the combined use of RA and 5-FU resulted in a much greater decrease in cell viability. A significant increase in apoptotic cell death was also observed compared with either treatment alone. This was accompanied by an augmentation in the pro-apoptotic genes APAF1 and BCL2L11, a reduction in the anti-apoptotic genes XIAP and NOL3, reduced expression of the proliferation-related marker MKI67, and suppression of the stemness-associated transcription factors OCT4 and NANOG. These results demonstrate that RA enhances the anticancer effects of 5-FU in gastric cancer cells through molecular alterations that may contribute to improved chemosensitivity. These results suggest that RA may improve the therapeutic response to 5-FU and represents a promising candidate for combination treatment of gastric cancer.

Keywords

• Apoptosis
• chemosensitivity
• fluorouracil
• gastric cancer
• rosmarinic acid

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