Chaperonin CCT-mediated AIB1 folding promotes the growth of ERα-positive breast cancer cells on hard substrates.
Clinical observations have revealed a strong association between estrogen receptor alpha (ERα)-positive tumors and the development of bone metastases, however, the mechanism underlying this association remains unknown. We cultured MCF-7 (ERα-positive) on different rigidity substrates. Compared with cells grown on more rigid substrates (100 kPa), cells grown on soft substrates (10 kPa) exhibited reduced spreading ability, a lower ratio of cells in the S and G2/M cell cycle phases, and a decreased proliferation rate. Using stable isotope labeling by amino acids (SILAC), we further compared the whole proteome of MCF-7 cells grown on substrates of different rigidity (10 and 100 kPa), and found that the expression of eight members of chaperonin CCT increased by at least 2-fold in the harder substrate. CCT folding activity was increased in the hard substrate compared with the soft substrates. Amplified in breast cancer 1 (AIB1), was identified in CCT immunoprecipitates. CCT folding ability of AIB1 increased on 100-kPa substrate compared with 10- and 30-kPa substrates. Moreover, using mammalian two-hybrid protein-protein interaction assays, we found that the polyglutamine repeat sequence of the AIB1 protein was essential for interaction between CCTζ and AIB1. CCTζ-mediated AIB1 folding affects the cell area spreading, growth rate, and cell cycle. The expressions of the c-myc, cyclin D1, and PgR genes were higher on hard substrates than on soft substrate in both MCF-7 and T47D cells. ERα and AIB1 could up-regulate the mRNA and protein expression levels of the c-myc, cyclin D1, and PgR genes, and that 17 β-estradiol could enhance this effects. Conversely, 4-hydroxytamoxifen, could inhibit these effects. Taken together, our studies demonstrate that some ERα-positive breast cancer cells preferentially grow on more rigid substrates. CCT-mediated AIB1 folding appears to be involved in the rigidity response of breast cancer cells, which provides novel insight into the mechanisms of bone metastasis.
Breast Disease Center, Southwest Hospital, Third Military Medical University, Chongqing, China; Burn Research Institute, Southwest Hospital, Third Military Medical University, Chongqing, China; National Key Laboratory of Trauma and Burns, Chongqing Key Laboratory of Disease Proteomics, Chongqing, China.
Li
L
Chen
Burn Research Institute, Southwest Hospital, Third Military Medical University, Chongqing, China; National Key Laboratory of Trauma and Burns, Chongqing Key Laboratory of Disease Proteomics, Chongqing, China.
Ze
Z
Zhang
Burn Research Institute, Southwest Hospital, Third Military Medical University, Chongqing, China; National Key Laboratory of Trauma and Burns, Chongqing Key Laboratory of Disease Proteomics, Chongqing, China.
Juhui
J
Qiu
Burn Research Institute, Southwest Hospital, Third Military Medical University, Chongqing, China; National Key Laboratory of Trauma and Burns, Chongqing Key Laboratory of Disease Proteomics, Chongqing, China.
Lingling
L
Zhang
Burn Research Institute, Southwest Hospital, Third Military Medical University, Chongqing, China; National Key Laboratory of Trauma and Burns, Chongqing Key Laboratory of Disease Proteomics, Chongqing, China.
Xiangdong
X
Luo
Breast Disease Center, Southwest Hospital, Third Military Medical University, Chongqing, China.
Jun
J
Jang
D001665:Binding Sites; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D018929:Cell Culture Techniques / Q000379:methods*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D056404:Chaperonin Containing TCP-1 / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry* / Q000494:pharmacology; D004129:Dimethylpolysiloxanes / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000187:drug effects; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D061986:MCF-7 Cells; D056921:Nuclear Receptor Coactivator 3 / Q000737:chemistry / Q000378:metabolism*; D017510:Protein Folding / Q000187:drug effects; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000494:pharmacology
D003470:Culture Media; D004129:Dimethylpolysiloxanes; D047628:Estrogen Receptor alpha; D013629:Tamoxifen; C016601:afimoxifene; D004958:Estradiol; C538866:NCOA3 protein, human; D056921:Nuclear Receptor Coactivator 3; D056404:Chaperonin Containing TCP-1