[Expression of XBP-1 in breast cancer cell lines and its role in ERalpha signaling].
Estrogen receptor (ERalpha) plays an important role in the development and progression of breast cancer. Several recent studies have demonstrated that expression of human X-box binding protein 1 (XBP-1) is associated with ERalpha status in breast tumors and overexpressed in a subset of breast tumors. XBP-1 has two splicing variants, which were designated as XBP-1S and XBP-1U, respectively. However, little is known about the expression pattern of XBP-1S and XBP-1U in breast cancer cells and about their roles in ERalpha signaling. In this study, the expression of two splicing forms of XBP-1 was detected in breast cancer cell lines with RT-PCR. Estrogen response element (ERE) -containing luciferase reporter assay was used to determine the effects of XBP-1S and XBP-1U on the transcription activity of ERalpha in MDA-MB-435 breast cancer cells. The result showed that both XBP-1S and XBP-1U enhanced the transcription activity of ERalpha in a hormone-independent and dose-dependent manner and the activity of of XBP-1S is higher than that of XBP-1U. Enhancement of ERE-containing luciferase reporter gene expression by XBP-1S and XBP-1U was dependent on ERalpha. These data suggest that XBP-1S and XBP-1U may play important roles in breast cancer growth and progression through ERalpha signaling.
Beijing Institute of Biotechnology, Beijing 100850, China.
Li-Hu
LH
Ding
Qi-Nong
QN
Ye
Qiu-Jun
QJ
Lu
Jian-Hua
JH
Zhu
Jing-Hua
JH
Yan
Zong-Hua
ZH
Wang
Cui-Fen
CF
Huang
D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D047628:Estrogen Receptor alpha; D005260:Female; D006801:Humans; D012333:RNA, Messenger / Q000032:analysis; D011960:Receptors, Estrogen / Q000502:physiology*; D000071701:Regulatory Factor X Transcription Factors; D020218:Response Elements / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D000071717:X-Box Binding Protein 1
D004268:DNA-Binding Proteins; D047628:Estrogen Receptor alpha; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605543:XBP1 protein, human