JAK2 Inhibitor, Fedratinib, Inhibits P-gp Activity and Co-Treatment Induces Cytotoxicity in Antimitotic Drug-Treated P-gp Overexpressing Resistant KBV20C Cancer Cells

Abstract

P-glycoprotein (P-gp) overexpression is one of the major mechanisms of multidrug resistance (MDR). Previously, co-treatment with Janus kinase 2 (JAK2) inhibitors sensitized P-gp-overexpressing drug-resistant cancer cells. In this study, we assessed the cytotoxic effects of JAK2 inhibitor, fedratinib, on drug-resistant KBV20C cancer cells. We found that co-treatment with fedratinib at low doses induced cytotoxicity in KBV20C cells treated with vincristine (VIC). However, fedratinib-induced cytotoxicity was little effect on VIC-treated sensitive KB parent cells, suggesting that these effects are specific to resistant cancer cells. Fluorescence-activated cell sorting (FACS), Western blotting, and annexin V analyses were used to further investigate fedratinib’s mechanism of action in VIC-treated KBV20C cells. We found that fedratinib reduced cell viability, increased G2 arrest, and upregulated apoptosis when used as a co-treatment with VIC. G2 phase arrest and apoptosis in VIC–fedratinib-co-treated cells resulted from the upregulation of p21 and the DNA damaging marker pH2AX. Compared with dimethyl sulfoxide (DMSO)-treated cells, fedratinib-treated KBV20C cells showed two-fold higher P-gp-inhibitory activity, indicating that VIC–fedratinib sensitization is dependent on the activity of fedratinib. Similar to VIC, fedratinib co-treatment with other antimitotic drugs (i.e., eribulin, vinorelbine, and vinblastine) showed increased cytotoxicity in KBV20C cells. Furthermore, VIC–fedratinib had similar cytotoxic effects to co-treatment with other JAK2 inhibitors (i.e., VIC–CEP-33779 or VIC–NVP-BSK805) at the same dose; similar cytotoxic mechanisms (i.e., early apoptosis) were observed between treatments, suggesting that co-treatment with JAK2 inhibitors is generally cytotoxic to P-gp-overexpressing resistant cancer cells. Given that fedratinib is FDA-approved, our findings support its application in the co-treatment of P-gp-overexpressing cancer patients showing MDR.

Low-Dose Rifabutin Increases Cytotoxicity in Antimitotic-Drug-Treated Resistant Cancer Cells by Exhibiting Strong P-gp-Inhibitory Activity

“…Our findings indicate that rifabutin displayed similar efficacy to the established strong P-gp inhibitors, aripiprazole, reserpine, and tariquidar (positive controls), at comparably lower doses. As P-gp inhibitors exhibit toxicity in normal cells [20][21][22][23], rifabutin with strong P-gp-inhibitory activity could be considered as a co-treatment drug to specifically target P-gp-overexpressing resistant cancer cells. As personalized medicines are gaining popularity, our findings regarding rifabutin might contribute to effective prescriptive options for P-gp-overexpressing drugresistant cancer patients.…”

“…As aripiprazole, reserpine, and tariquidar display strong P-gp-inhibitory activities [20][21][22][23], they were used as positive controls. These well-known P-gp inhibitors were highly cytotoxic to P-gp-overexpressing KBV20C cells owing to their strong P-gp-inhibiting activity [20][21][22][23].…”

“…As aripiprazole, reserpine, and tariquidar display strong P-gp-inhibitory activities [20][21][22][23], they were used as positive controls. These well-known P-gp inhibitors were highly cytotoxic to P-gp-overexpressing KBV20C cells owing to their strong P-gp-inhibiting activity [20][21][22][23]. The number of KBV20C cells that accumulated rhoda-mine123 (a well-known P-gp substrate) following treatment with the potential P-gp inhibitors or positive controls was determined.…”

Contribution of Cancer-Targeting Drugs toward Faster Clinical Application

“…Four research articles discuss novel combination drug treatments to target various types of cancers which remain difficult to treat with cancer-targeting drugs. Oh et al [ 1 ] report novel findings of combination treatment with a chemotherapeutic drug and JAK2 inhibitor for P-gp-overexpressing resistant cancer cells. The study focuses on a Food and Drug Administration (FDA)-approved JAK2 inhibitor by exploring a drug repositioning strategy.…”

“…Considering that this study targeted HPV-positive cervical cancer cells, a specific type of tumor, it can be deemed as a personalized medicine and narrowed down to specific drug treatment. As fedratinib and bazedoxifene are currently applied in clinical settings [ 1 , 7 ], drug repositioning offers an efficient method to address the urgent need for the pharmacological treatment of drug-resistant cancer, affording treatment approval at a relatively rapid pace.…”