CD320 expression is increased in breast cancer stem cells but does not promote their expansion or alter key histone methylation marks

Several lines of evidence suggest a potential link between stemness and vitamin B12, which contributes to S-adenosylmethionine (SAM) generation and hence methylation-dependent epigenetic control. Here we found that the vitamin B12 receptor, CD320, is significantly increased in cancer stem cells (CSCs) in models of triple-negative breast cancer <i>.</i> We hypothesized that elevated CD320 expression promotes CSC expansive self-renewal via increased SAM-mediated histone H3K4 and H3K36 trimethylation, which were previously implicated in stemness and plasticity. However, we found that modulation of CD320 expression had no effect on SAM, H3K4me3 and H3K36me3 levels, or on CSC expansion <i>in vitro</i> .