Melanoma Differentiation-associated Gene 7/IL-24 Exerts Cytotoxic Effects by Altering the Alternative Splicing of Bcl-x Pre-mRNA via the SRC/PKCδ Signaling Axis

Abstract

A number of studies have demonstrated that the overexpression of Bcl-x(L) in cells confers apoptosis resistance as well as cooperates with oncogenic factors (e.g. c-Myc) in tumorigenesis (1-10). The regulation of Bcl-x(L) expression can be complex at times, consisting of both transcriptional and post-transcriptional processes. In regard to post-transcriptional processing/ alternative splicing, the BCL-x gene, via alternative 5Ј splice site (5ЈSS) 5 selection within exon 2, produces either the Bcl-x(s) isoform through activation of an upstream/proximal 5ЈSS or the Bcl-x(L) isoform through activation of a downstream/distal 5ЈSS. A number of studies have demonstrated that Bcl-x(s), in contrast to Bcl-x(L), promotes apoptosis (9,(11)(12)(13)(14). Hence, the alternative 5ЈSS selection of Bcl-x pre-mRNA emerged as a potential target for anti-cancer therapeutics. For example, Taylor et al. (15) demonstrated that Bcl-x 5ЈSS selection can be specifically modulated using antisense oligonucleotides specific against the Bcl-x(L) 5Ј splice site. Treatment of cells with these oligonucleotides induced an increase in the expression of Bcl-x(s) and a decrease in the expression of Bcl-x(L), resulting in sensitization of NSCLC cells to chemotherapeutic agents (15). These findings were also demonstrated by Kole and co-* This work was supported by research grants from the Veteran's Administration (VA Merit Review, I BX001792 (to C. E. C.) and a Research Career Scientist Award, 13F-RCS-002 (to C. E. C.)); from the Vietnam Education Foundation (fellowship to N. T. V.); from the National Institutes of Health via Grants HL125353 (to C. E. C.), HD087198 (to C. E. C.), CA117950 (to C. E. C.), CA154314 (to C. E. C.), RR031535 (to C. E. C.), CA192613 (to P. D.), CA097318 (to P. B. F.), CA127641 (to P. B. F.), P01 CA104177 (to P. B. F.), and a T32 PostDoctoral Fellowship (Postdoctoral Training Program in Cancer Biology, CA085159) (to B. A. S.); from the United States-Israel Binational Science Foundation via Grant BSF#2011360 (to C. E. C.); and from the National Foundation for Cancer Research (to P. B. F.). The authors declare that they have no conflicts of interest with the contents of this article.

Splice variants of cytosolic polyadenylation element–binding protein 2 (CPEB2) differentially regulate pathways linked to cancer metastasis

“…Cells were passaged once every 3 to 5 days (ϳ90% confluence), and all experiments were performed during the first 12 passages. Antibodies were purchased from Cell Signaling Technology with the exception of anti-CPEB2 (Santa Cruz Biotechnology) and anti-HIF1␣ (Abcam) (7,(23)(24)(25)(26)(27).…”

“…Plasmid transfections were accomplished using the Effectene system (Qiagen) according to manufacturer's instructions as described previously (7,(22)(23)(24)(25)(26) or Amaxa Nucleofector (Kit V).…”

“…Total protein (10 -20 g) was electrophoretically separated on 7.5-10% polyacrylamide gels. Samples were transferred electrophoretically to PVDF membranes, then probed with the appropriate antibody as described previously (7,(22)(23)(24)(25)(26).…”

“…Primer/probe sets were described previously (7). PCR was performed as described (22)(23)(24)(25)(26). cDNA was synthesized using the Superscript III kit (Life Technologies) and manufacturer's instructions.…”

miR‐203a‐3p.1 targets IL‐24 to modulate hepatocellular carcinoma cell growth and metastasis

“…IL-24 expression is lost in most cancer cells of human origin [2][3][4]. Studies have shown that loss of IL-24 expression is correlated with disease progression in prostate cancer [5], breast cancer [6], colon cancer [7], neuroblastoma [8], acute leukemia [9], oral squamous cell carcinoma [10,11], lung cancer [12] and other cancers [13][14][15][16][17]. Exogenous IL-24 expression has anti-tumor, anti-angiogenic and anti-metastatic properties and suppresses various signaling pathways, without harming normal cells [2][3][4][5].…”