6,7-dimethoxy-1,2,3,4-tetrahydro-isoquinoline-3-carboxylic acid attenuates colon carcinogenesis via blockade of IL-6 mediated signals.

In this study, we investigated the in vivo antiproliferative activity of 6,7-dimethoxy-1,2,3,4-tetrahydro-isoquinoline-3-carboxylic acid (M1) in dimethylhydrazine (DMH) induced colorectal carcinoma (CRC) using albino Wistar rats. M1 was administered to DMH induced CRC rats at 10 and 25 mg/kg doses for 15 days. Various physiological, oxidative parameters, histopathology, ELISA, gene and protein expression studies were conducted to evaluate the anti-CRC potential of M1. The histopathology and biochemical tests indicated the protective action of M1 in DMH-induced colon cancer. ELISA confirms that M1 reduced the increased concentration of IL-6 more prominently than those of IL-2 and COX-2. Gene expression analysis revealed that M1 attenuated the increased mRNA over-expression of IL-6, JAK2 and STAT3. The result obtained from quantitative western blot analysis demonstrated that the CRC condition was produced by the IL-6 induced activation/phosphorylation of JAK2 and STAT3 and further down-regulated with M1 treatment. This evidence was supported well with the application of data-based mathematical modeling. Applying the fitted model, we predicted the quantitative behavior of STAT3 populations not accessible to experimental measurement. Later, H NMR based serum metabolic profiling was carried out using rat sera to investigate the impact of M1 on CRC-induced metabolic alterations. M1 showed its ability to restore the perturbed metabolites in CRC condition. Altogether, our study provided the first time evidence that M1 exhibits anti-CRC potential through the blockade of IL-6/JAK2/STAT3 oncogenic signaling.