Biology subjects

Iwakuma, T.

Publications and source records attributed to Iwakuma, T..

3 recordsLinked to original sources

bioRxiv2026

The combination of EWSR1-FLI1 and loss of one EWSR1 allele leads to the induction of trisomy 8

Ewing sarcoma is a pediatric cancer that develops in skeletal elements. The majority of Ewing sarcoma patients carry the aberrant EWSR1-FLI1 fusion gene. Despite trisomy 8 being an additional common aberration associated with a poor prognosis for patients, its induction mechanism remains unknown. When the EWSR1-FLI1 gene is formed, the cell loses one wildtype EWSR1 allele. To elucidate the induction mechanism of trisomy 8, we generated a cell line that allows for the conditional induction of EWSR1-FLI1 expression and EWSR1 knockdown (derived from a single EWSR1 allele. Specifically, the conditional cell line was generated by integrating the Tet-on EWSR1-FLI1 construct into the AAVS locus and adding a miniAID tag at the 5 end of the EWSR1 locus using auxin-degron system. A combination of the EWSR1-FLI1 expression and degradation of one allele-derived EWSR1 induced a high incidence of trisomy 8 within eight days, enhancing colony formation. Mechanistically, trisomy 8 is induced by the haploinsufficiency of EWSR1, and the remaining EWSR1 proteins are likely inhibited by interaction with EWSR1-FLI1. Our data showed that the knockout of EWSR1 alone was sufficient to increase the incidence of trisomy 8. Expression of wild-type EWSR1 in EWSR1 knockout cells rescued the high incidence of trisomy 8. In contrast, the EWSR1:R565A mutant, which lacks the ability to interact with Aurora B kinase, failed to rescue this phenotype. We propose that the combination of EWSR1-FLI1 expression and loss of EWSR1 contributes to the induction of trisomy 8 through the compromised EWSR1-Aurora B pathway. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=135 SRC="FIGDIR/small/726567v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@999891org.highwire.dtl.DTLVardef@1ef6748org.highwire.dtl.DTLVardef@65e475org.highwire.dtl.DTLVardef@179da40_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2021

RNA binding protein RBM3 augments kissing loop formation with lncRNAs to enhance translational control

It is becoming apparent that translational regulation involves the coordinated actions of RNA binding proteins (RBPs) and non-coding RNAs. For efficient translation, mRNA needs to be circularized, which is catalyzed by RNA binding proteins and translation factors. However, the role of lncRNAs in the process is not yet defined. We first performed RNA-seq and RNA- immunoprecipitation coupled-Seq and identified LSAMP-3 and Flii-1. Moreover, modeling studies suggest enhanced kissing loop interactions including of transcripts that encode angiogenesis and epithelial mesenchymal transition. While intestinal epithelial cell specific RBM3 transgenic mice showed increased LSAMP-3 and Flii-1, this was reduced in knockout mice. Also, RBM3 overexpression increased tumor xenograft growth, this was suppressed by knockdown of the lncRNAs. Also, knockdown of endogenous RBM3 reduced lncRNA levels and tumor xenograft growth. In addition, it reduced colitis-associated cancers. We propose that RBPs such as RBM3 mediate their function through regulatory lncRNAs that enable circularization to control translation.

cancer biology↗

bioRxiv2020

Mutant p53 suppresses innate immune signaling to promote tumorigenesis

Mutations in the p53 tumor suppressor occur very frequently in human cancer. Often, such mutations lead to the constitutive overproduction of mutant p53 (mtp53) proteins, which can exert a cancer-promoting gain-of-function (GOF). We have identified a novel mechanism by which mtp53 controls both cell-autonomous and non-cell autonomous signaling to promote cancer cell survival and suppress tumor immune surveillance. Mtp53 interferes with the function of the cytoplasmic DNA sensing machinery, cGAS-STING-TBK1-IRF3, that controls the activation of the innate immune response. We find that mtp53, but not wildtype p53, binds to TANK binding protein kinase (TBK1) and inhibits both its basal and agonist-induced activity. The association of mtp53 with TBK1 prevents the formation of a trimeric complex between TBK1-STING-IRF3, which is required for activation, nuclear translocation and transcriptional activity of IRF3. Mtp53 knockdown restores TBK1 activity, resulting in the transcriptional induction of IRF3 target genes and IRF3-dependent apoptosis. Furthermore, inactivation of innate immune signaling by mtp53 alters cytokine production resulting in immune evasion. Restored TBK1 signaling was sufficient to bypass mtp53 and reactivate cell-autonomous and non-cell autonomous tumor control. Thus, overriding mtp53s inhibition of this cytosolic DNA sensing pathway may ultimately lead to restored immune cell function and cancer cell eradication.

cancer biology↗