Natural sesquiterpenes as potential modulator of intracellular pathways in CCA proliferation

Many natural compounds are able to control apoptotic signaling pathways particularly by modulating the NFkB and STAT3 cascades. The natural sesquiterpenes β-caryophyllene (CRY) and beta-caryophyllene oxide (CRYO) exhibited in vitro chemosensitizing properties in different human cancer cell lines, among which liver cancer cells. Cholangiocarcinoma (CCA), that originates at the level of the intrahepatic or extrahepatic bile ducts,is one the most aggressive type of cancer for its chemotherapy resistance and invasiveness. Increasing efforts are directed to identify new cellular targets for cancer cell survival and metastatization and some alternative approaches. In this context, ourprevious studies highlighted that a combined treatment of low-dose doxorubicin (DOXO) and a nontoxic concentration of CRY(10 μg/mL) and CRYO (10 μg/mL) increased the effectiveness of the anticancer drug. Present study was aimed at identifyingthe possible interference of the combined treatment of low-dose DOXO and CRY or CRYO on the STAT3 activation pathway inCCA cells. To this end, cholangiocytes were exposed to the test substances for 24h and 72h, before to evaluate the apoptosis,through the Annexin V staining, and the nuclear translocation of STAT3, through immunofluorescence. We found that DOXO in association with CRY, but not with CRYO, suppresses the STAT3 activation in CCA cells with a time-dependent effect.Accordingly, an increased apoptosis was found in cholangiocytes treated with DOXO + CRY, compared to DOXO alone. Our results show for the first time that the combination DOXO and CRY is able to modulate the STAT3 pathway and could be considered ablocker of the same signaling cascade.