TSPAN1 overexpression as an indicator of poor prognosis in estrogen receptor-positive breast cancer.

Background: Tetraspanin 1 (TSPAN1) is a newly discovered protein of the tetrameric protein family encoded by the TSPAN1 gene localized in the 1p34 chromosome region. TSPAN1 has been shown to be associated with various malignancies. In this study, we aimed to investigate the prognostic significance of TSPAN1 in breast cancer. Estrogen receptor-positive (ER+) breast cancer is the largest breast cancer subgroup, and ER-targeted therapies have significantly prolonged survival and improved symptoms in advanced breast cancer. TSPAN1 overexpression was found to be associated with a poor prognosis in ER+ breast cancer.

Methods: We analyzed the expression of TSPAN1 in breast cancer tissues and cell lines using western blotting and quantitative reverse transcription polymerase chain reaction (RT-qPCR).

Results: TSPAN1 expression was higher in breast cancer cells as compared with normal breast tissue. There was a significant association between a high TSPAN1 level and a low survival rate. Inhibition of TSPAN1 significantly reduced the proliferation and invasion of BT474 cells both in vitro and in vivo. The downregulation of TSPAN1 in breast cancer cells significantly reduced the levels of p-mitogen-activated protein kinase 1 (MEK1) (S298) and p-extracellular signal-regulating kinase (ERK) 1/2.

Conclusions: TSPAN1 modulates downstream extracellular matrix (ECM) receptor signaling cascades and promotes cellular proliferation and invasion in breast cancer. TSPAN1 inhibition may be a potential new treatment strategy for breast cancer.