Conjugated and non-conjugated androgens differentially modulate specific early gene transcription in breast cancer in a cell-specific manner

The role of androgen in breast cancer development is not fully understood, although androgen receptors (ARs) have been identified in breast cancer clinical samples and cell lines. However the whole spectrum of androgen actions cannot be accounted to the classic AR activation and the possible existence of a cell surface-AR has been suggested. Indeed, androgen, like all steroids, has been reported to trigger membrane-initiated signaling activity and exert specific actions, including ion channels and kinase signaling pathway activation, ultimately affecting gene expression. However, the molecular nature of membrane androgen sites represents another major persisting question. In the present study, we investigated early transcriptional effects of testosterone and the impermeable testosterone-BSA conjugate, in two breast cancer cell lines (T47D and MDA-MB-231), in an attempt to decipher specific genes modified in each case, providing evidences about specific membrane-initiating actions. Our data indicate that the two agents affect the expression of several genes. A group of genes were commonly affected while others were uniquely modified by each agent, including interaction with growth factors and K+-channels. In MDA-MB-231 cells, that are AR negative, the majority of genes affected by testosterone were also affected by testosterone-BSA indicating a membrane-initiated action. Subsequent analysis revealed that the two agents trigger different molecular pathways and cellular/molecular functions, suggestive of a molecular or functional heterogeneity of membrane and intracellular AR. In addition, the reported phenotypic interactions of membrane-acting androgen with growth factor were verified at the transcriptomic level, as well as their ion channel-modifying effects. Finally an interesting interplay between membrane-acting androgen with inflammation-related molecules, with potential clinical implications was revealed.