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01.12.2018 | Research article | Ausgabe 1/2018 Open Access

BMC Cancer 1/2018

FAM3B/PANDER inhibits cell death and increases prostate tumor growth by modulating the expression of Bcl-2 and Bcl-XL cell survival genes

Zeitschrift:
BMC Cancer > Ausgabe 1/2018
Autoren:
Paula Maciel-Silva, Izabela Caldeira, Icaro de Assis Santos, Ana Claudia Oliveira Carreira, Flavia Ramos Siqueira, Eliane Antonioli, Anna Carla Goldberg, José Ernesto Belizário, Humberto Miguel Garay-Malpartida
Wichtige Hinweise

Electronic supplementary material

The online version of this article (https://​doi.​org/​10.​1186/​s12885-017-3950-9) contains supplementary material, which is available to authorized users.

Abstract

Background

FAM3B/PANDER is a novel cytokine-like protein that induces apoptosis in insulin-secreting beta-cells. Since in silico data revealed that FAM3B can be expressed in prostate tumors, we evaluated the putative role of this cytokine in prostate tumor progression.

Methods

FAM3B expression was analyzed by quantitative PCR in tumor tissue clinical samples and prostate tumor cell lines. Culture growth and viability of DU145 cell line were evaluated after treatment with either exogenous FAM3B protein obtained from conditioned media (CM) of 293 T cells overexpressing FAM3B or a recombinant FAM3B protein produced in a bacterial host. DU145 cells overexpressing FAM3B protein were produced by lentiviral-mediated transduction of full-length FAM3B cDNA. Cell viability and apoptosis were analyzed in DU145/FAM3B cells after treatment with several cell death inducers, such as TNF-alpha, staurosporine, etoposide, camptothecin, and serum starvation conditions. Anchorage-independent growth in soft agarose assay was used to evaluate in vitro tumorigenicity. In vivo tumorigenicity and invasiveness were evaluated by tumor xenograft growth in nude mice.

Results

We observed an increase in FAM3B expression in prostate tumor samples when compared to normal tissues. DU145 cell viability and survival increased after exogenous treatment with recombinant FAM3B protein or FAM3B-secreted protein. Overexpression of FAM3B in DU145 cells promoted inhibition of DNA fragmentation and phosphatidylserine externalization in a time and dose-dependent fashion, upon apoptosis triggered by TNF-alpha. These events were accompanied by increased gene expression of anti-apoptotic Bcl-2 and Bcl-XL, decreased expression of pro-apoptotic Bax and diminished caspase-3, −8 and −9 proteolytic activities. Furthermore, inhibition of Bcl-2 anti-apoptotic family proteins with small molecules antagonists decreases protective effects of FAM3B in DU145 cells. When compared to the respective controls, cells overexpressing FAM3B displayed a decreased anchorage- independent growth in vitro and increased tumor growth in xenografted nude mice. The immunohistochemistry analysis of tumor xenografts revealed a similar anti-apoptotic phenotype displayed by FAM3B-overexpressing tumor cells.

Conclusions

Taken together, by activating pro-survival mechanisms FAM3B overexpression contributes to increased resistance to cell death and tumor growth in nude mice, highlighting a putative role for this cytokine in prostate cancer progression.
Zusatzmaterial
Additional file 1: Figure S1. Cell proliferation assays in DU145/FAM3B cells (A) Viable DU145/FAM3B and DU145-control cells were harvested and counted under a light microscope using the trypan blue exclusion method at 48 h intervals during 15 days to determine growth curves. The growth curves shown represent data from three separate experiments. (B) Cell proliferation was measured by labeling cells with bromodeoxyuridine (BrdU) incorporation assay kit according to manufacturer’s protocol. The results are expressed as means of three independent experiments and as relative ratios to BrdU incorporation in DU145-control cells. (TIFF 2263 kb)
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Literatur
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