Conjugated and non-conjugated androgen differentially modulate gene expression in breast cancer cell lines.

The role of androgen in breast cancer development is not fully understood although androgen receptors (AR) have been identified in breast cancer clinical samples and cell lines. However the whole spectra of androgen actions cannot be accounted to the classic AR mode of action and the possible existence of a cell surface AR has been suggested. Indeed androgens like all steroids have been reported to trigger membrane initiated signaling activity and exert specific actions. Androgens acting on the membrane can rapidly activate kinase signaling pathways and ultimately could affect gene expression. However, the molecular nature of membrane androgen binding 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, 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 tested affect the expression of several genes. A group of genes were commonly affected while others were uniquely modified by each agent. 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 action. Subsequent analysis revealed that the two agents trigger different molecular pathways and cellular/molecular functions, suggestive of a molecular heterogeneity of membrane and intracellular AR. In addition, the phenotypic interactions of membrane-acting androgen with growth factor were verified at the transcriptomic level. Finally an interesting interplay between membrane-acting androgen with inflammation-related molecules, with potential clinical implications was revealed.

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Notas G, Pelekanou V, Castanas E, Kampa M