In this week's Science, an international research team reports that certain gut microbes can influence the growth and spread of liver cancer, suggesting that the microbiome could be a target for therapeutic intervention for the disease. In mouse models of liver cancer, the team found that reducing commensal bacteria with antibiotics led to a reduction in the number of tumors — an effect associated with with an increase in activated liver natural killer cells. Further analysis shows that antibiotic treatment caused increased liver expression of the ligand CXCL16 — which helps recruit the natural killer cells — and that this activity is apparently caused by the bacterium genus Clostridium. Notably, increasing levels of Clostridium in the mice led to a decrease of natural killer cells in the liver and tumor metastasis.
And in Science Translational Medicine, a group of Chinese investigators publishes a study showing the anti-cancer potential of a synthetic small circular single-stranded DNA (CSSD) that is designed to absorb the oncogenic microRNA miR9. Earlier studies had shown that cancer patients with low tumor expression of the tumor-suppressor genes KLF17, CDH1, and LASS2 — all of which are suppressed by miR9 — had shortened survival times. As such, the researchers used CSSD to increase the genes' expression, which inhibited tumor proliferation and metastasis, and promoted apoptosis in vitro, ex vivo, and in patient-derived xenograft models. The findings provide "new insights into the miRNA-based resurrection of 'co-silenced' tumor suppressor genes and reports a precise multitarget drug for potential tumor therapy," the authors conclude.