14-3-3 zeta mediated epithelial -mesenchymal transition (EMT) contributes to ErbB2 overexpressing ductal carcinoma in situ (DCIS) progression into invasive breast cancer

Jing Lu, The University of Texas Grad. Sch. of Biomed. Sci. at Houston

Abstract

ErbB2, is overexpressed in 20-30% of invasive/metastatic breast cancers, but is more frequently detected in an early stage, non-invasive breast cancer ductal carcinoma in situ (DCIS) (50-60%). It is still not clear how a sub-group of the ErbB2 overexpressing DCIS progress into invasive breast cancer. ^ Our lab recently found that high levels of both ErhB2 and 14-3-3 zeta expression in breast cancer patients correlated with poor clinical outcome. More interestingly, our lab also found that co-overexpression of ErbB2 and 14-3-3 zeta in DCIS associated with recurrence of invasive disease. Therefore, I hypothesized that: ErbB2 and 14-3-3 zeta cooperatively drive DCIS progression into invasive breast cancer. I generated MCF10A cells overexpressing either ErbB2 alone or both ErbB2 and 14-3-3 zeta. ErbB2 overexpression in MCF-10A cells (grown in 3-dimensional matrigel culture) led to the disruption of acinar structures with no invasion, which mimics DCIS in vivo. Interestingly, co-overexpression of ErbB2 and 14-3-3 zeta in MCF10A cells led to further disrupted acinar structures formation, with strikingly invasive properties. I found that ErbB2 overexpression led to increased migration. 14-3-3 zeta overexpression led to epithelial-mesenchymal transition (EMT), with reduced expression of epithelial cell proteins, and de novo expression of mesenchymal cell proteins. Further studies demonstrated that loss of E-cadherin, the key event of EMT phenotype, was mediated by Smad interacting protein 1 (SIP-1) upregulation. SIP-1 is a zinc-finger transcriptional repressor that is regulated by TGFβ/Smads pathway. I found that 14-3-3 zeta interacted with TGFβ receptor I to stabilize it. The increased TGFβ receptor I led to the increased phospho-Smad3 levels in the nuclei of 10A.ErbB2.zeta cells, where it bound to SIP-1 promoter to upregulate SIP-1 expression. Indeed, inhibition of TGFβ/Smads pathway by its inhibitor led to a partial recovery of E-cadherin expression, which correlated with less invasive phenotype of 10A.ErbB2.zeta cells. Thus, ErbB2 overexpression contributed to the increased migration, while 14-3-3 zeta overexpression contributed to the decreased cell-cell adhesion via regulating EMT. Taken together, co-overexpression of ErbB2 and 14-3-3 zeta promoted invasion in MCF10A cells. ^ Therefore, co-overexpression of ErbB2 and 14-3-3 zeta in DCIS patients may indicate a higher risk of progression into invasive breast cancer. ^

Subject Area

Biology, Cell

Recommended Citation

Lu, Jing, "14-3-3 zeta mediated epithelial -mesenchymal transition (EMT) contributes to ErbB2 overexpressing ductal carcinoma in situ (DCIS) progression into invasive breast cancer" (2008). Texas Medical Center Dissertations (via ProQuest). AAI3305166.
http://digitalcommons.library.tmc.edu/dissertations/AAI3305166

Share

COinS