Pretreatment with methanolic extract of Pistacia lentiscus L. increases sensitivity to DNA damaging drugs in primary high-grade serous ovarian cancer cells

Introduction: Ovarian cancer remains the most lethal gynecologic cancer in women. Despite achievements in surgical and systemic therapy, most patients develop platinum resistance. Thus, new strategies to increase or reverse the platinum sensitivity in ovarian cancer patients are urgently needed. In this study, we aimed to investigate the anti-cancer effect of the leaves of Pistacia lentiscus L medicinal plants used in Algerian traditional medicine on ovarian cancer cells in vitro. Methods: Four newly established primary cell lines derived from ascites of patients with high-grade serous and clear cell ovarian cancer were used to test the anti-cancer effect of the leaves of Pistacia lentiscus L. An experimental study was performed to study the therapeutic effects of the plant leaves substances in patient derived models. The anti- proliferative activity of ethanolic, acetonic and methanolic plant leaves extracts was measured by cell viability assays, and the apoptotic effect assessed using flow cytometry analysis. The impact on constitutive active oncogenic pathways and cytokine release in cell culture supernatant were monitored by Western blotting and ELISA, respectively. Results: Sequencing analysis confirmed the presence of mutations in several genes, such as TP53, RB1, PIK3C, which are commonly mutated in high-grade serous ovarian cancer. Obtained results indicated a cytotoxic effect of the methanolic extract of P. lentiscus L (MEPL) on primary cell line cultures, inhibiting PI3K/AKT and MAPK/ERK signaling pathways, and decreasing the release of IL6 and VEGF by the malignant cells. Moreover, treatment with MEPL enhanced the sensitivity to platinum-based chemotherapy in our primary cell lines of patients. Conclusion: Methanolic extract of P. lentiscus L might be a promising candidate for novel therapeutic approaches in combination with classic chemotherapy for patients with high-grade serous ovarian cancer.