Evaluating The Mechanisms Of Proliferative Inhibitor Isolated From Marine Sponge Symbionts In Experimental Liver Carcinogenesis

Abstract

Hepatocellular carcinoma (HCC) is the most common primary cancer of the liver and is the fourth most common cause of cancer- related death worldwide. The phosphatidylinositol 3 protein kinase (PI3K)/AKT pathway is a vital and majorly explored intracellular signaling pathway in tumorigenesis and is commonly upregulated in HCC. Therefore, designing drugs that regulate PI3K/AKT will have a significant impact on the prevention and eradication of HCC. Marine sponges and their symbiotic microbiota are considered as a rich source of anticancer metabolites. Therefore, our study was initiated to explore PI3K inhibitor molecule from bacterial symbionts of Marine Sponges. In this regards, Sponge samples were collected from Gulf of Mannar, India and isolated 12 bacterial strains. Among them Bacillus pumilus AMK1 isolated from Callyspongia fistularis sponge showed potent cytotoxic activity by MTT assay against HepG2 cancer cell line. Further purifying the bio-molecules responsible for the cytotoxic activity by different spectral analysis (HPLC, LC-MS/MS, FTIR, NMR) led to the identification of Cyclo(-Pro-Tyr) (CPT), a dipeptide that showed promising cytotoxic activity and apoptotic inducing activity on HepG2 liver cancer cell line. Supporting this, the protein expression levels of PI3K/AKT pathway markers PI3K, p-PI3K, AKT, p-AKT and apoptotic protein markers Bcl2, Bax, Caspase-3, PARP and Cyt-c/p53 were significantly altered compared with control groups in both invitro and invivo studies. newline newline newlineFurther in order to enhance the anticancer effect, CPT was conjugated with ZnO nanoparticles and evaluated for anticancer activity. newline newline newline newlineIt was observed that ZnO-CPT showed enhanced cytotoxicity against HepG2 cells and showed a significant higher apoptosis. In addition to this, the toxicity study on zebrafish embryos concluded that ZnONP- CPT was toxic and teratogenic activities against zebrafish embryo only at higher concentrations. Hence with all the above results, it is concluded that naturally available CPT