Evaluating the therapeutic efficacy of the US FDA-designated Orphan drug, uttroside B in impeding hepatocarcinogenesis via induction of immunogenic apoptosis, using a murine model of Aflatoxin B1-induced liver carcinogenesis

Abstract

The sustained exposure to aflatoxin B1 (AFB1), a mycotoxin produced by Aspergillus sp., is one of the fundamental causes of hepatocellular carcinoma (HCC). We have previously documented the exceptional anti-HCC potential and pharmacological safety of uttroside B, a phytosaponin isolated in our lab (Utt-B). The current results indicate that Utt-B mitigates tumor development in mice that have been subjected to AFB1 exposure. Utt-B was found to be cytotoxic towards primary liver cancer cells cultured from mice bearing AFB1-induced liver tumors and the compound effectively prevented the formation of AfBO-DNA adducts in AFB1-induced liver tumors as well as primary liver cancer cells. In vitro studies revealed that treatment with Utt-B resulted in the induction of damage associated molecular patterns such as, ROS, HSP70 and inflammatory cytokines, IL-1{beta} and CXCL-10, suggesting the potential of Utt-B in triggering immunogenic cell death. Mechanistically, treatment with Utt-B enhances the antigen presentation potential, causes blockade of the major immune checkpoint molecules, namely, CTLA-4, PD-1, TIM-3, LAG-3 and TOX, and potentiates immunogenic apoptosis in the hepatic tumor microenvironment of mice pre-exposed to AFB1 via the activation of Zap70/Lck/GRZB signaling axis. Interestingly, it was also observed that Utt-B could abrogate the mutations induced by AFB1 in a concentration dependent manner. Taken together, the findings of the current study attest Utt-B as a propitious drug candidate against HCC.