Dataset Information

Expression and alternative splicing of the cyclin-dependent kinase inhibitor-3 gene in human cancer.

ABSTRACT: The cyclin-dependent kinase inhibitor-3 (CDKN3) gene encodes a dual-specificity protein tyrosine phosphatase that dephosphorylates CDK1/CDK2 and other proteins. CDKN3 is often overexpressed in human cancer, and this overexpression correlates with reduced survival in several types of cancer. CDKN3 transcript variants and mutations have also been reported. The mechanism of CDKN3 overexpression and the role of CDKN3 transcript variants in human cancer are not entirely clear. Here, we review the literature and provide additional data to assess the correlation of CDKN3 expression with patient survival. Besides the full-length CDKN3 encoding transcript and a major transcript that skips exon 2 express in normal and cancer cells, minor aberrant transcript variants have been reported. Aberrant CDKN3 transcripts were postulated to encode dominant-negative inhibitors of CDKN3 as an explanation for overexpression of the perceived tumor suppressor gene in human cancer. However, while CDKN3 is often overexpressed in human cancer, aberrant CDKN3 transcripts occur infrequently and at lower levels. CDKN3 mutations and copy number alternation are rare in human cancer, implying that neither loss of CDKN3 activity nor constitutive gain of CDKN3 expression offer an advantage to tumorigenesis. Recently, it was found that CDKN3 transcript and protein levels fluctuate during the cell cycle, peaking in mitosis. Given that rapidly growing tumors have more mitotic cells, the high level of mitotic CDKN3 expression is the most plausible mechanism of frequent CDKN3 overexpression in human cancer. This finding clarifies the mechanism of CDKN3 overexpression in human cancer and questions the view of CDKN3 as a tumor suppressor.

SUBMITTER: Cress WD

PROVIDER: S-EPMC5641230 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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Expression and alternative splicing of the cyclin-dependent kinase inhibitor-3 gene in human cancer.

Cress W Douglas WD Yu Peng P Wu Jie J

The international journal of biochemistry & cell biology 20170511 Pt B

The cyclin-dependent kinase inhibitor-3 (CDKN3) gene encodes a dual-specificity protein tyrosine phosphatase that dephosphorylates CDK1/CDK2 and other proteins. CDKN3 is often overexpressed in human cancer, and this overexpression correlates with reduced survival in several types of cancer. CDKN3 transcript variants and mutations have also been reported. The mechanism of CDKN3 overexpression and the role of CDKN3 transcript variants in human cancer are not entirely clear. Here, we review the lit ...[more]

PMID: 28504190

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Project description:BackgroundThe expression signature of deregulated long non-coding RNAs (lncRNAs) and related genetic variants is implicated in every stage of tumorigenesis, progression, and recurrence. This study aimed to explore the association of lncRNA cyclin-dependent kinase inhibitor 2B antisense RNA 1 (CDKN2B-AS1) gene expression and the rs2383207A>G intronic variant with breast cancer (BC) risk and prognosis and to verify the molecular role and networks of this lncRNA in BC by bioinformatics gene analysis.MethodsSerum CDKN2B-AS1 relative expression and rs2383207 genotypes were determined in 214 unrelated women (104 primary BC and 110 controls) using real-time PCR. Sixteen BC studies from The Cancer Genome Atlas (TCGA) including 8925 patients were also retrieved for validation of results.ResultsCDKN2B-AS1 serum levels were upregulated in the BC patients relative to controls. A/A genotype carriers were three times more likely to develop BC under homozygous (OR = 3.27, 95% CI 1.20-8.88, P = 0.044) and recessive (OR = 3.17, 95% CI 1.20-8.34, P = 0.013) models. G/G homozygous patients had a higher expression level [median and quartile values were 3.14 (1.52-4.25)] than A/G [1.42 (0.93-2.35)] and A/A [1.62 (1.33-2.51)] cohorts (P = 0.006). The Kaplan-Meier curve also revealed a higher mean survival duration of G/G cohorts (20.6 months) compared to their counterparts (A/A: 15.8 and A/G: 17.2 months) (P < 0.001). Consistently, BC data sets revealed better survival in cohorts with high expression levels (P = 0.003). Principal component analysis (PCA) showed a deviation of patients who had shorter survival towards A/A and A/G genotypes, multiple lesions, advanced stage, lymphovascular invasion, and HER2+ receptor staining. Ingenuity Pathway Analysis (IPA) showed key genes highly enriched in BC with CDKN2B-AS1.ConclusionsThe findings support the putative role of CDKN2B-AS1 as an epigenetic marker in BC and open a new avenue for its potential use as a therapeutic molecular target in this type of cancer.

Project description:Novel treatments for glioblastoma, the most common malignant primary brain tumor, are urgently required. Type I interferons (IFN) are natural cytokines primarily involved in the defense against viral infections, which may also serve a role in the control of cancer, notably in the suppression of the cancer stem cell phenotype. TG02 is a novel orally available cyclin-dependent kinase 9 inhibitor which induces glioma cell apoptosis without profound caspase activation, which is currently explored in early clinical trials in newly diagnosed and recurrent glioblastoma. In the present study, human glioma-initiating cell line models were used to explore whether IFN-? modulates the anti-glioma activity of TG02. The present study employed immunoblotting to assess protein levels, several viability assays and gene silencing strategies to assess gene function. Pre-exposure to IFN-? sensitized human glioma models to a subsequent exposure to TG02. Combination treatment was associated with increased DEVD-amc cleaving caspase activity that was blocked by the anti-apoptotic protein, BCL2. However, BCL2 did not protect from the synergistic effects of IFN and TG02 on glioma cell growth. Furthermore, although IFN strongly induced pro-apoptotic XIAP-associated factor (XAF) expression, disrupting XAF expression did not abrogate the synergy with TG02. Consistent with that, caspase 3 gene silencing did not abrogate the effects of TG02 or IFN-? alone or in combination. Finally, it was observed that IFN-? may indeed modulate the effects of TG02 upstream in the signaling cascade since inhibition of RNA polymerase II phosphorylation, a direct readout of the pharmacodynamic activity of TG02, was facilitated when glioma cells were pre-exposed to IFN-?. In summary, these data suggest that type I IFN may be combined with TG02 to limit glioblastoma growth, but that the well characterized effects of IFN and TG02 on apoptotic signaling are dispensable for synergistic tumor growth inhibition. Instead, exploring how IFN signaling primes glioma cells for TG02-mediated direct target inhibition may help to design novel and effective pharmacological approaches to glioblastoma.

Dataset Information

Expression and alternative splicing of the cyclin-dependent kinase inhibitor-3 gene in human cancer.

Publications

Expression and alternative splicing of the cyclin-dependent kinase inhibitor-3 gene in human cancer.

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