Attenuation of TGF-β signaling suppresses premature senescence in a p21-dependent manner and promotes oncogenic Ras-mediated metastatic transformation in human mammary epithelial cells

Shu Lin, Junhua Yang, Abdel G. Elkahloun, Abhik Bandyopadhyay, Long Wang, John E. Cornell, I. Tien Yeh, Joseph Agyin, Gail Tomlinson, Lu Zhe Sun

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29 Scopus citations


The molecular mechanisms that drive triple-negative, basal-like breast cancer progression are elusive. Few molecular targets have been identified for the prevention or treatment of this disease. Here we developed a series of isogenic basal-like human mammary epithelial cells (HMECs) with altered transforming growth factor-β (TGF-β) sensitivity and different malignancy, resembling a full spectrum of basal-like breast carcinogenesis, and determined the molecular mechanisms that contribute to oncogene-induced transformation of basal-like HMECs when TGF-β signaling is attenuated. We found that expression of a dominant-negative type II receptor (DNRII) of TGF-β abrogated autocrine TGF-β signaling in telomerase-immortalized HMECs and suppressed H-Ras-V12-induced senescence-like growth arrest (SLGA). Furthermore, coexpression of DNRII and H-Ras-V12 rendered HMECs highly tumorigenic and metastatic in vivo in comparison with H-Ras-V12-transformed HMECs that spontaneously escaped H-Ras-V12-induced SLGA. Microarray analysis revealed that p21 was the major player mediating Ras-induced SLGA, and attenuated or loss of p21 expression contributed to the escape from SLGA when autocrine TGF-β signaling was blocked in HMECs. Furthermore, knockdown of p21 also suppressed H-Ras-V12-induced SLGA. Our results identify that autocrine TGF-β signaling is an integral part of the cellular anti-transformation network by suppressing the expression of a host of genes, including p21-regulated genes, that mediate oncogene-induced transformation in basal-like breast cancer.

Original languageEnglish (US)
Pages (from-to)1569-1581
Number of pages13
JournalMolecular Biology of the Cell
Issue number8
StatePublished - Apr 15 2012


ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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