FAT10 mediates the effect of TNF-α in inducing chromosomal instability

Abstract

SummaryTumor necrosis factor-alpha (TNF-a) plays important roles in chronic inflammation-associated tumorigenesis but the mechanisms involved remain poorly understood. Previously, we reported that high levels of FAT10 led to chromosomal instability that is mediated by an abbreviated mitotic phase. Here, we show that TNF-a induces FAT10 gene expression through TNF receptor 1 (TNFR1) and activates the NF-kB pathway in HCT116 and SW620 cells. TNF-a treatment also leads to an abbreviated mitotic phase that can be reversed by inhibiting FAT10 expression. This abbreviated mitotic phase is correlated with a TNF-a-induced reduction in the kinetochore localization of MAD2 during prometaphase which, again, can be reversed by inhibiting FAT10 gene expression. There is greater variability of chromosome numbers in HCT116 and SW620 cells treated with TNF-a than in untreated cells, which can be reversed by the introduction of short hairpin RNA (shRNA) against FAT10. The more stable chromosome numbers in HCT116 cells expressing FAT10 shRNA can revert to greater variability with the addition of a mutant FAT10 that is not recognized by the FAT10 shRNA. Upon TNF-a stimulation, higher cell death is observed when FAT10 expression is inhibited by shRNA. These data strongly suggest that FAT10 plays an important role in mediating the function of TNF-a during tumorigenesis by inducing cell cycle deregulation and chromosomal instability, and by inhibiting apoptosis.

The ubiquitin-like modifier FAT10 in cancer development

“…Tumor formation by TNF-␣-induced and thus FAT10 expressing HCT116 cells in nude mice was diminished when the mice were treated at the same time with silibinin which correlated with reduced FAT10 expression in the tumors. The dependency of endogenous FAT10 expression on NF-B signaling was further supported by data showing that the induction of FAT10 expression by TNF-␣ was greatly diminished when p65 was downregulated by specific siRNAs in HCT116 and HepG2 cells (Gao et al, 2015;Ren et al, 2011).…”

“…As already pointed out, FAT10 mRNA and protein expression is highly and synergistically inducible in all cell types by the pro-inflammatory cytokines IFN-␥ and TNF-␣ (Aichem et al, 2010;Raasi et al, 1999;Ren et al, 2011) or by a combination of TNF-␣ and IL-6 as shown in HepG2 cells (Choi et al, 2014). In HCT116 cells it was shown, that TNF-␣ signaling via the TNF-␣ receptor 1 (TNFR1) induced FAT10 expression, a receptor mainly found on tumor and stromal cells where it mediates the activation of NF-B (Balkwill, 2009;Ren et al, 2011). The analysis of the FAT10 promoter sequence revealed seven potential p65/NF-B binding sites as well as three binding sites for transcription factors of the family of signal transducer and activator of transcription (STAT)3 (Canaan et al, 2006;Choi et al, 2014;Gao et al, 2015).…”

“…On the one hand FAT10 may act as a regulator of NF-B signaling and on the other hand FAT10 expression itself is regulated by NF-B. As already pointed out, FAT10 mRNA and protein expression is highly and synergistically inducible in all cell types by the pro-inflammatory cytokines IFN-␥ and TNF-␣ (Aichem et al, 2010;Raasi et al, 1999;Ren et al, 2011) or by a combination of TNF-␣ and IL-6 as shown in HepG2 cells (Choi et al, 2014). In HCT116 cells it was shown, that TNF-␣ signaling via the TNF-␣ receptor 1 (TNFR1) induced FAT10 expression, a receptor mainly found on tumor and stromal cells where it mediates the activation of NF-B (Balkwill, 2009;Ren et al, 2011).…”

“…In FAT10 overexpressing HCT116 cells as well as in TNF-␣-treated HCT116 cells, the localization of MAD2 at the kinetochores was much reduced in the prometaphase of the cell cycle, indicating that FAT10 interferes with the binding of MAD2 to kinetochores (Fig. 2B) (Ren et al, 2006(Ren et al, , 2011. Moreover, after release from G1/S arrest, FAT10 overexpressing cells showed a delayed entry into mitosis.…”

“…Upregulation of endogenous FAT10 expression by TNF-␣ as well as overexpression of FAT10 has directly been linked to chromosomal instability in several reports (Gao et al, 2015;Ren et al, 2006Ren et al, , 2011Theng et al, 2014). It was shown that about 60% of HCT116 and HepG2 cells which had been treated for about ten passages with IFN-␥ and TNF-␣ displayed abnormally high chromosome numbers in a karyotype analysis and inhibition of FAT10 expression with silibinin, a potent inhibitor of the NF-B signaling pathway, was able to abolish this effect (Gao et al, 2015).…”