Oxyphenbutazone promotes cytotoxicity in rats and Hep3B cellsvia suppression of PGE2 and deactivation of Wnt/β-catenin signaling pathway

Abstract

Hepatocellular carcinoma (HCC) is the fifth leading cause of death and is generally typified by elevated liver enzyme biomarkers, antioxidants, and chronic inflammation of hepatocytes. Although currently available drugs have shown remarkable alleviation of the cancerous condition, but at the same time they present a more severe challenge of toxic effects due to chemotherapy. Therefore, in order to bring more patient-compliant therapy, we aimed to refurbish the use of a COX inhibitor, oxyphenbutazone (OPB), with low dose of methotrexate (MTX) to treat diethyl nitrosamine (DENA)-induced HCC in Wistar rats and in Hep3B cells. Hep3B cells were subjected to assays like in vitro cytotoxicity, DNA synthesis, and caspase activity. The combination index was also evaluated, succeeding the cytotoxicity assay, to analyze the possible synergism. For in vivo study, Wistar strain male rats were given single intraperitoneal dose of DENA (200 mg/kg) and were supplied with sodium phenobarbital (0.1% in tap water) for promoting tumorigenesis throughout the study. MTX (2.5 and 5.0 mg/kg/week, ip) and OPB (70 mg/kg/week, po in two divided doses) were administered to the treatment groups from 3rd week till the termination of study. Several biochemical parameters including biomarkers of liver function, antioxidant enzymes, and histopathological examination of liver cells were tested. Significant synergism was witnessed in the cytotoxicity assay when Hep3B cells received varied dose combination treatment of MTX (0.25, 0.5, or 1.0 µmol/L) and OPB (2.5, 5.0, or 7.5 µmol/L). MTX (0.5 and 1.0 µmol/L) in combination with OPB (5.0 or 7.5 µmol/L) inhibited the cell proliferation as BrdU incorporation was quite low in DNA synthesis analysis, as well as caspase-9/-3 cascade was activated which led to apoptosis of cancer cells. Co-treatment with MTX and OPB exerted potential anticancer activity in rats than either of the drugs alone. Administration of combination therapy harmonized the DENA-induced elevation of serum biochemical parameters, including but not limited to, α-fetoprotein (AFP), alanine- and aspartate-aminotransferase, alkaline phosphatase, vascular endothelial growth factor (VEGF), and antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), and lipid per oxidation (LPO). All these results were optimally substantiated by histopathological examination. As evident COX-2 catalyzes the synthesis of PGE2, needed in the activation of Wnt/β-catenin pathway, which in turn is responsible for activating the transcriptional proteins required for higher degree of cell division and thence growth. Therefore, inhibition of COX-2 by our novel combination infers that even low doses of MTX can elucidate noticeable anticancer activity when paired with OPB.