Effects of FSTL1 on cell proliferation in breast cancer cell line MDA-MB-231 and its brain metastatic variant MDA-MB-231-BR

Abstract

In the past decades, altered Follistatin-like 1 (FSTL1) expression has been documented in a variety of cancers, while its functional roles are poorly understood. Particularly in breast cancer, the expression of FSTL1 and its signaling pathway remain to be determined. In the present study, an elevated FSTL1 expression and a supressed cell proliferation were detected in a specific brain metastatic cell line MDA-MB-231-BR (231-BR), compared with its parental cell line MDA-MB-231. However, this protein was hardly detected in the other three breast cancer cell lines. Next, lentiviral vectors encoding FSTL1 or FSTL1 specific shRNAs were used to overexpress or knock down FSTL1 in MDA-MB-231 or 231-BR, respectively (MDA-MB-231FSTL1 or 231-BRsh FSTL1). Results showed that overexpression of FSTL1 inhibited MDA-MB-231 cell proliferation, while knockdown of FSTL1 in 231-BR cells promotes cell proliferation, compared with their corresponding control groups. These results were further confirmed in nude mouse xenografts. The tumor volume in 231-BR cell-bearing mice was significantly smaller than that of MDA-MB-231 group, and reduction of tumor volume was detected in MDA-MB-231FSTL1 cell-bearing mice compared with the control group. Previous studies revealed that TGF-β-Smad2/3 signaling pathway was activated in 231-BR and MDA-MB-231FSTL1 cells, which may contribute to the inhibited cell proliferation. In addition, Smad3 knockdown could restore the inhibition of cell proliferation induced by FSTL1 overexpression in MDA-MB-231FSTL1 cells, indicating that the anti-proliferative effect of FSTL1 overexpression may be associated with Smad3 involved TGF-β signaling pathway regulation. This study identified FSTL1 as an inhibitor of cell proliferation in MDA-MB-231 and 231-BR cell lines, which may provide new insights into the development and management of breast cancer.

Deficiency of Follistatin-Like Protein 1 Accelerates the Growth of Breast Cancer Cells at Lung Metastatic Sites

“…FSTL1 inhibits cell proliferation through smad3 in MBA-MD-231 cells, as observed previously [ 27 ]. To explore the function of FSTL1 in vivo , we employed FSTL1 deficient mice.…”

The glycoprotein follistatin-like 1 promotes brown adipose thermogenesis

“…Brown preadipocytes were transfected with lentiviral vector containing shRNA sequences for relevant RNA interference experiments and then subjected to differentiation. The experimental details were shown in our previously study [30]. To overexpress PPARγ2 in brown adipocytes, lentiviruses were produced by transfecting pLVX-PPARγ2 plasmids (a kind gift from Dr. Huang), pSPAX2 and pMD2G (purchased from Addgene) into 293T cells, viral particles accumulated in the supernatant and high-titer viral preparations could be obtained by ultracentrifugation, lentivirus was titrated before transfecting into brown adipocytes with polybrene.…”

Follistatin-like 1 in development and human diseases

“…On the other hand, increased expression of FSTL1 compared to healthy control tissue was observed in brain cancer cells [ 18 ], in fibroblasts but not in epithelial cells in colon tumours [ 59 ], in castration-recurrent prostate cancer [ 60 ], in most cases of hepatocellular carcinomas (HCC) [ 61 ], in head and neck squamous cell carcinoma (HNSCC) [ 62 ], and esophageal squamous cell carcinoma (ESCC) [ 63 ]. FSTL1 is higher expressed in metastatic brain tumours compared to primary breast cancer [ 64 ]. FSTL1 is not expressed at a detectable level in normal brain tissue and in diffuse-infiltrating astrocytes of grade II or III gliomas, but is expressed at high levels in grade IV gliomas, referred to as glioblastoma [ 18 ].…”

“…Transfection of lung NSCLC cell lines (PC-14 and H446) [ 58 , 67 , 68 ], ovarian, endometrial [ 19 ], NPC [ 22 ], and breast cancer [ 64 ] cell lines with FSTL1 reduces their growth rate via an unknown signaling pathway. Overexpression of FSTL1 in ovarian or endometrial cells was also found to increase the rate of apoptosis via a death receptor-initiated pathway.…”