Abstract 4380: Role of FAM3B/PANDER in inhibition of cell death and tumor growth in breast and prostate cancer

Abstract

Abstract FAM3B/PANDER is a novel cytokine-like protein that induces apoptosis in beta-cells and regulates the effects of insulin in peripheral tissues. Since previous data revealed that FAM3B can be expressed by prostate and breast tumors, we evaluated the role of this cytokine in prostate and breast tumor progression. FAM3B expression was compared by quantitative PCR in LnCAP, PC-3 and DU145 prostate tumor cell lines and MCF-7 and MDA-MB- 231 breast tumor cell lines. After treatment with either recombinant FAM3B protein or secreted FAM3B obtained from conditioned media (CM) derived from FAM3B-overexpressing 293T cells, the cell death and viability of DU145 and MDA-MB- 231 cell lines were evaluated. DU145 and MDA-MB- 231 cells overexpressing FAM3B protein were produced by lentiviral-mediated transduction of full-length FAM3B cDNA. Cell viability and apoptosis were analyzed in DU145-FAM3B and MDA-231-FAM3B cells after treatment with cell death inducers. Anchorage-independent growth and scratch wound assays were used to evaluate in vitro tumorigenicity and cell migration, respectively. In vivo tumorigenicity and invasiveness were evaluated by tumor xenograft growth in nude mice. We observed that FAM3B was highly expressed by hormone responsive cells (LnCAP and MCF-7) and low expressed in unresponsive hormone cells (PC-3, DU145 and MDA-MB- 231). Cell viability and survival of DU145 and MDA-MB- 231 cells increased after exogenous treatment with recombinant FAM3B protein or CM containing FAM3B-secreted protein. Overexpression of FAM3B in DU145 and MDA-MB- 231 cells promoted an inhibition of apoptosis triggered by TNF-alpha and staurosporine. Cell death inhibition was accompanied by increased gene expression of the anti-apoptotic Bcl-2 and Bcl-xL genes, and by slight decrease in expression of pro-apoptotic gene Bax and with a decrease of caspases proteolytic activities. When compared to control, cells overexpressing FAM3B displayed a decreased anchorage independent growth and increased motility in vitro, as well as an increased tumor growth in xenografted nude mice. In agreement Immunohistochemistry analysis from tumor xenografts revealed similar anti-apoptotic phenotype in FAM3B overexpression, with an increase of Bcl-2. The results showed that FAM3B was capable to activates pro-survival mechanisms with an increasing of tumor growth by, activation of Bcl-2 and Bcl-xl pathways, suggesting the role of this cytokine in breast and in prostate tumors progression. Citation Format: Izabela D. Caldeira. Role of FAM3B/PANDER in inhibition of cell death and tumor growth in breast and prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4380.