4-Aryl-1,3,2-oxathiazolylium-5-olate: a novel GST inhibitor to release JNK and activate c-Jun for cancer therapy

Purpose The over-expression of glutathion S -transferase Pi (GSTπ) in tumors and inhibitory effect of GSTπ to JNK are two possible causes of the development of drug-resistance in chemotherapy. This research is to develop a novel pH-controlled NO donor to inhibit GSTπ(and to activate the JNK/c-Jun pathway (omit “to induce apoptosis”). Methods Four 4-Aryl-1,3,2-oxathiazolylium-5-olate (OZO) derivatives with varying aryl para- substitutions (–H, –CF 3 , –Cl, and –OCH 3 ) were synthesized. Anticancer activity was determined by MTS assay. GST activity was measured with spectrophotometry using 1-chlro-2,4-dinitrobenzene (CDNB) and GSH as substrates. (omit “Apoptosis was evaluated by annexin V staining and flow cytometry”). c-Jun N-terminal kinase 1 (JNK1) association with GSTπ and activation of c-Jun were evaluated with immunoprecipitation and western blot. Results OZO derivatives showed anticancer effect against leukemia and breast cancer cells by MTS assay. The relative potency of their anticancer effects is OZO-H > OZO-Cl, OZO-OMe > OZO-CF 3 . The anticancer activity of these compounds was correlated with their inhibition of GST activity in cancer cells. The immunoprecipitaion result showed that the treatment of OZO-H released JNK1 from GSTπ-JNK1 complex. Consequently, the treatment of OZO-H in cancer cells induced JNK1 phophorylation and activated c-Jun in cancer cells. Conclusion OZO-H is a novel GST inhibitor to release JNK1 for activation of JNK/c-Jun pathway (original is “c-Jun to trigger apoptosis in cancer cells”). It provides a new class of GST target compound for anticancer therapy.