ESR1 and breast carcinoma: However, to our knowledge, HIF-1α inhibition of AR gene expression has not been reported in the past, although HIF-1α has been shown to repress transcription of the carbamoyl phosphate synthetase-aspartate carbamoyltransferase-dihydroorotase gene in normal cells [58] and the estrogen receptor alpha gene in breast cancer cells [48].