ASH2L drives proliferation and sensitivity to bleomycin and other genotoxins in Hodgkin's lymphoma and testicular cancer cells

It is of clinical importance to identify biomarkers predicting the efficacy of DNA damaging drugs (genotoxins) so that non-responders are not unduly exposed to the deleterious effects of otherwise inefficient drugs. Using a whole genome CRISPR/Cas9 gene knockout approach we have identified that low levels of ASH2L cause resistance to genotoxins. ASH2L is a core component of the H3K4 methyl transferase complex. We show that ASH2L absence decreases cell proliferation and favors DNA repair upon genotoxin exposure. The cell models we have used are derived from cancers currently treated either partially (Hodgkins lymphoma), or entirely (testicular cancer) with genotoxins. For such cancers, ASH2L levels could be used as a biomarker to predict the response to genotoxins. Our data also indicate that patients with low ASH2L expressing tumors do not develop resistance to ATR inhibitors. In these patients, such inhibitors may represent an alternative treatment to DNA damaging drugs.