journal contribution
posted on 2023-03-30, 21:50 authored by Nilay Shah, Kideok Jin, Leigh-Ann Cruz, Sunju Park, Helen Sadik, Soonweng Cho, Chirayu Pankaj Goswami, Harikrishna Nakshatri, Rajnish Gupta, Howard Y. Chang, Zhe Zhang, Ashley Cimino-Mathews, Leslie Cope, Christopher Umbricht, Saraswati Sukumar <p>PDF file, 154K, Table S1: Primers used for PCR ; Table S2. Antibodies used for Western Blot ; Table S3 Treatment comparisons of tumor volumes at selected time points. ; Table S4: Treatment comparisons of tumor volumes at selected time points -MCF7-HOXB13 cell line, SC xenografts ; Table S5: Treatment comparisons of tumor volumes at selected time points MCF7-LPCX cell line, MFP xenografts ; Table S6. Treatment comparisons of tumor volumes at selected time points-MCF7-HOXB13 cell line, MFP xenografts.</p>
History
ARTICLE ABSTRACT
Most breast cancers expressing the estrogen receptor α (ERα) are treated successfully with the receptor antagonist tamoxifen (TAM), but many of these tumors recur. Elevated expression of the homeodomain transcription factor HOXB13 correlates with TAM-resistance in ERα-positive (ER+) breast cancer, but little is known regarding the underlying mechanism. Our comprehensive evaluation of HOX gene expression using tiling microarrays, with validation, showed that distant metastases from TAM-resistant patients also displayed high HOXB13 expression, suggesting a role for HOXB13 in tumor dissemination and survival. Here we show that HOXB13 confers TAM resistance by directly downregulating ERα transcription and protein expression. HOXB13 elevation promoted cell proliferation in vitro and growth of tumor xenografts in vivo. Mechanistic investigations showed that HOXB13 transcriptionally upregulated interleukin (IL)-6, activating the mTOR pathway via STAT3 phosphorylation to promote cell proliferation and fibroblast recruitment. Accordingly, mTOR inhibition suppressed fibroblast recruitment and proliferation of HOXB13-expressing ER+ breast cancer cells and tumor xenografts, alone or in combination with TAM. Taken together, our results establish a function for HOXB13 in TAM resistance through direct suppression of ERα and they identify the IL-6 pathways as mediator of disease progression and recurrence. Cancer Res; 73(17); 5449–58. ©2013 AACR.
