Here is the most recent research on pubmed by Rana (maybe explaining benefit of blocking estrogen with chemo in ER+..i.e.
chemoendocrine therapy):
Cancer Res. 2010 Feb 15;70(4):1731-40. Epub 2010 Feb 9.
Estrogen Suppresses MLK3-Mediated Apoptosis Sensitivity in ER+ Breast Cancer Cells.
Rangasamy V,
Mishra R,
Mehrotra S,
Sondarva G,
Ray RS,
Rao A,
Chatterjee M,
Rana B,
Rana A.
Authors' Affiliations: Department of Pharmacology and Division of Gastroenterology, Hepatology and Nutrition, Department of Medicine, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois; Department of Pathology, Scott and White Hospital and Texas A&M Health Science Center, College of Medicine, Temple, Texas; Division of Biochemistry, Department of Pharmaceutical Technology, Jadavpur University, Kolkata, India; and Hines Veterans Affairs Medical Center, Hines, Illinois.
Little knowledge exists about the mechanisms by which estrogen can impede chemotherapy-induced cell death of breast cancer cells. 17beta-Estradiol (E(2)) hinders cytotoxic drug-induced cell death in estrogen receptor-positive (ER(+)) breast cancer cells. We noted that the activity of the proapoptotic mixed lineage kinase 3 (MLK3) kinase was relatively higher in estrogen receptor-negative (ER(-)) breast tumors, suggesting that E(2) might inhibit MLK3 activity. The kinase activities of MLK3 and its downstream target, c-Jun NH(2)-terminal kinase, were rapidly inhibited by E(2) in ER(+) but not in ER(-) cells. Specific knockdown of AKT1/2 prevented MLK3 inhibition by E(2), indicating that AKT mediated this event. Furthermore, MLK3 inhibition by E(2) involved phosphorylation of MLK3 Ser(674) by AKT, attenuating the proapoptotic function of MLK3. We found that a pan-MLK inhibitor (CEP-11004) limited Taxol-induced cell death and that E(2) accentuated this limitation. Taken together, our findings indicate that E(2) inhibits the proapoptotic function of MLK3 as a mechanism to limit cytotoxic drug-induced death of ER(+) breast cancer cells. Cancer Res; 70(4); 1731-40.
PMID: 20145118 [PubMed - in process]