Furthermore, MUC1-CD is also involved in promoting expression of multi drug resistance (MDR) genes and finally, silencing MUC1 expression was together with resensitization of human epidermal growth factor receptor 2 positive (HER2+) and/or estrogen receptor (ER+) positive breast cancer cells to bortezomib, trastuzumab and tamoxifen respectively.
Total mucin-1 (CA 15-3) levels are rather inversely associated with tumor grade and SPF, and elevated levels even indicate prolonged DFS in ER+ breast cancer patients.