HNF1β drives glutathione (GSH) synthesis underlying intrinsic carboplatin resistance of ovarian clear cell carcinoma (OCCC)

Abstract

Chemoresistance to platinum-based antineoplastic agents is a consistent feature among ovarian carcinomas; however, whereas high-grade serous carcinoma (OSC) acquires resistance during chemotherapy, ovarian clear cell carcinoma (OCCC) is intrinsically resistant. The main objective of this study was to explore, in vitro and in vivo, if hepatocyte nuclear factor 1β (HNF1β) and glutaminolysis contribute for the resistance of OCCC to carboplatin through the intrinsically increased GSH bioavailability. To disclose the role of HNF1β, experiments were also performed in an OSC cell line, which does not express HNF1β. Metabolic profiles, GSH quantification, HNF1β, and γ-glutamylcysteine ligase catalytic subunit (GCLC) and modifier subunit (GCLM) expression, cell cycle, and death were assessed in ES2 cell line (OCCC) and OVCAR3 cell line (OSC); HNF1β knockdown was performed in ES2 and murine model of subcutaneous and peritoneal OCCC tumors was established to test buthionine sulphoxamine (BSO), as a sensitizer to carboplatin. Glutaminolysis is activated in ES2 and OVCAR3, though ES2 exclusively synthesizes amino acids and GSH. ES2 cells are more resistant to carboplatin than OVCAR3 and the abrogation of GSH production by BSO sensitizes ES2 to carboplatin. HNF1β regulates the expression of GCLC, but not GCLM, and consequently GSH production in ES2. In vivo, BSO prior to carboplatin reduces dramatically subcutaneous tumor size and GSH levels, as well as peritoneal dissemination. Our study discloses HNF1β as the mediator of intrinsic OCCC chemoresistance and sheds a light to re-explore a cancer adjuvant therapeutic approach using BSO to overcome the lack of efficient therapy in OCCC.

Integrating modern approaches to pathogenetic concepts of malignant transformation of endometriosis

“…HNF-1β may repair damage caused by oxidative stress and can promote survival by upregulating antioxidant proteins via binding with antioxidant response element (37,68,81,83,84). This gene upregulates the synthesis of glutathione (GSH), a powerful antioxidant (85). HNF-1β also triggers ROS resistance in CCC cells via rBAT, a cystine transporter (68).…”

Modern approaches to noninvasive diagnosis of malignant transformation of endometriosis

“…EAOC allows the rapid reduction of metHb possibly through the conversion of metHb into oxyHb (in vivo autoreduction). Glutathione, an antioxidant overexpressed in EAOC, is shown to be responsible for the conversion of metHb to oxyHb (14,15). The difference in the metHb-to-oxyHb ratio between benign and malignant endometriosis supports the hypothesis that this is not a consequence of the simple dilution of the cyst fluids.…”

Polyurea Dendrimer Folate-Targeted Nanodelivery of l-Buthionine Sulfoximine as a Tool to Tackle Ovarian Cancer Chemoresistance

“…The platinum drugs induce cell death through two mechanisms: the establishment of adducts of DNA and proteins, and the generation of reactive oxygen species (ROS) [9,10]. We have previously found that ovarian cancer cells exhibit a great metabolic reliance on cysteine and glutathione (GSH), as these thiols were shown to protect cells under stressful conditions such as hypoxia or carboplatin exposure, hence, also accounting for chemoresistance [11][12][13]. GSH can explain this protective effect given its role as a ROS scavenger and as a pivotal drug detoxifier, allowing cells to evade cell death [14][15][16][17][18].…”

“…GSH can explain this protective effect given its role as a ROS scavenger and as a pivotal drug detoxifier, allowing cells to evade cell death [14][15][16][17][18]. We have reported that chemoresistance, supported by high GSH levels, can be abrogated upon the exposure to l-buthionine sulfoximine (l-BSO) [11], an inhibitor of γ-glutamylcysteine ligase (GCL), the first enzyme catalyzing the synthesis of GSH [19,20]. However, the systemic administration of l-BSO is associated to an elevated toxicity, since l-BSO is an irreversible inhibitor of GCL [19].…”