Bethany N. Hannafon

Oklahoma nitrone-007 is an effective anticancer therapeutic agent targeting inflammatory and immune metabolism pathways in endometrial cancer

Advanced-stage endometrial cancer patients typically receive a combination of platinum and paclitaxel chemotherapy. However, limited treatment options are available for those with recurrent disease, and there is a need to identify alternative treatment options for the advanced setting. Our goal was to evaluate the preclinical efficacy and mechanism of action of the anticancer drug Oklahoma Nitrone-007 (OKN-007) alone and in combination with carboplatin and paclitaxel in endometrial cancer. The effect of OKN-007 on the metabolic viability of endometrial cancer cells in both two- and three-dimensional (2D and 3D) cultures, as well as on clonogenic growth, in vitro was assessed. We also evaluated OKN-007 in vivo using an intraperitoneal xenograft model and targeted gene expression profiling to determine the molecular mechanism and gene expression programs altered by OKN-007. Our results showed that endometrial cancer cells were generally sensitive to OKN-007 in both 2D and 3D cultures. OKN-007 displayed a reduction in 3D spheroid and clonogenic growth. Subsequent targeted gene expression profiling revealed that OKN-007 significantly downregulated the immunosuppressive immunometabolic regulatory enzyme indolamine 2,3-dioxygenase 1 (IDO1) (-11.27-fold change) and modulated upstream inflammatory pathways that regulate IDO1 expression (interferon-gamma [IFN-γ], Janus kinase/signal transducer and activator of transcription [JAK-STAT], transforming growth factor beta [TGF-β], and nuclear factor-kappa B [NF-κB]), downstream IDO1 effector pathways (mammalian target of rapamycin [mTOR] and aryl hydrocarbon receptor [AhR]), and altered T cell signaling pathways. OKN-007 treatment reduced IDO1, sulfatase 2 (SULF2), and TGF-β protein expression in vivo and inhibited TGF-β, NF-κB, and AhR-mediated nuclear signaling in vitro. These findings indicate that OKN-007 surmounts proinflammatory, immunosuppressive, and protumorigenic pathways and is a promising approach for the effective treatment of endometrial cancer. SIGNIFICANCE STATEMENT: Women with advanced and recurrent endometrial cancer have limited therapeutic options. Oklahoma Nitrone-007 (OKN-007), which has minimal toxicity and is currently being evaluated in early-phase clinical trials for the treatment of cancer, is a potential new strategy for the treatment of endometrial cancer.

Targeting doublecortin-like kinase 1 reveals a novel strategy to circumvent chemoresistance and metastasis in ovarian cancer

Ovarian cancer (OvCa) has a dismal prognosis because of its late-stage diagnosis and the emergence of chemoresistance. Doublecortin-like kinase 1 (DCLK1) is a serine/threonine kinase known to regulate cancer cell "stemness", epithelial-mesenchymal transition (EMT), and drug resistance. Here we show that DCLK1 is a druggable target that promotes chemoresistance and tumor progression of high-grade serous OvCa (HGSOC). Importantly, high DCLK1 expression significantly correlates with poor overall and progression-free survival in OvCa patients treated with platinum chemotherapy. DCLK1 expression was elevated in a subset of HGSOC cell lines in adherent (2D) and spheroid (3D) cultures, and the expression was further increased in cisplatin-resistant (CPR) spheroids relative to their sensitive controls. Using cisplatin-sensitive and resistant isogenic cell lines, pharmacologic inhibition (DCLK1-IN-1), and genetic manipulation, we demonstrate that DCLK1 inhibition was effective at re-sensitizing cells to cisplatin, reducing cell proliferation, migration, and invasion. Using kinase domain mutants, we demonstrate that DCLK1 kinase activity is critical for mediating CPR. The combination of cisplatin and DCLK1-IN-1 showed a synergistic cytotoxic effect against OvCa cells in 3D conditions. Targeted gene expression profiling revealed that DCLK1 inhibition in CPR OvCa spheroids significantly reduced TGFβ signaling, and EMT. We show in vivo efficacy of combined DCLK1 inhibition and cisplatin in significantly reducing tumor metastases. Our study shows that DCLK1 is a relevant target in OvCa and combined targeting of DCLK1 in combination with existing chemotherapy could be a novel therapeutic approach to overcome resistance and prevent OvCa recurrence.