Correction: Kedzierska, H., et al. Decreased Expression of SRSF2 Splicing Factor Inhibits Apoptotic Pathways in Renal Cancer. Int. J. Mol. Sci. 2016, 17, 1598.

The authors wish to make the following corrections to this paper [1]: in Figure 4 the same gelscans were mistakenly pasted to illustrate splicing changes of: i) BIM in KIJ-265T and KIJ308T cells,and ii) MCL-1 in UOK171 and KIJ-265T [...].

microRNA-mediated regulation of splicing factors SRSF1, SRSF2 and hnRNP A1 in context of their alternatively spliced 3'UTRs.

SRSF1, SRSF2 and hnRNP A1 are splicing factors that regulate the expression of oncogenes and tumor suppressors. SRSF1 and SRSF2 contribute to the carcinogenesis in the kidney. Despite their importance, the mechanisms regulating their expression in cancer are not entirely understood. Here, we investigated the microRNA-mediated regulation of SRSF1, SRSF2 and hnRNP A1 in renal cancer. The expression of microRNAs predicted to target SRSF1, SRSF2 and hnRNP A1 was disturbed in renal tumors compared with controls. Using qPCR, Western blot/ICC and luciferase reporter system assays we identified microRNAs that contribute to the regulation of expression of SRSF1 (miR-10b-5p, miR-203a-3p), SRSF2 (miR-183-5p, miR-200c-3p), and hnRNP A1 (miR-135a-5p, miR-149-5p). Silencing of SRSF1 and SRSF2 enhanced the expression of their targeting microRNAs. miR-183-5p and miR-200c-3p affected the expression of SRSF2-target genes, TNFRSF1B, TNFRSF9, CRADD and TP53. 3'UTR variants of SRSF1 and SRSF2 differed by the presence of miRNA-binding sites. In conclusion, we identified a group of microRNAs that contribute to the regulation of expression of SRSF1, SRSF2 and hnRNP A1. The microRNAs targeting SRSF1 and SRSF2 are involved in a regulatory feedback loop. microRNAs miR-183-5p and miR-200c-3p that target SRSF2, affect the expression of genes involved in apoptotic regulation.

The role of SRSF1 in cancer.

SRSF1 jest wielofunkcyjnym bialkiem bioracym udzial w procesach zwiazanych z metabolizmem RNA. Nastepstwem zaburzen ekspresji SRSF1, obserwowanych w wielu typach nowotworów, sa nieprawidlowosci w skladaniu pre-mRNA, zmiany stabilnosci transkryptów i poziomu translacji onkogenów oraz genów supresorowych. Regulujac róznicowe skladanie transkryptów genów CCND1, RAC1, KLF6, BCL2L1, MCL1 oraz CASP9, SRSF1 indukuje zmiany w cyklu komórkowym, proliferacji i apoptozie. Czynnik SRSF1 wplywa takze na angiogeneze nowotworowa i przerzutowanie, m.in. promujac powstawanie proangiogennych wariantów VEGF oraz wariantu splicingowego genu RON, który aktywuje proces przejscia nablonkowo-mezenchymalnego. Ze wzgledu na istotna role SRSF1 w rozwoju i progresji nowotworów, bialko to jest obiecujacym celem terapii przeciwnowotworowych wykorzystujacych zwiazki hamujace jego aktywnosc. W artykule przedstawiono najnowsze informacje o wplywie SRSF1 na nowotworzenie oraz jego potencjalne znaczenie w opracowaniu nowych strategii w leczeniu chorych z nowotworami.

Decreased Expression of SRSF2 Splicing Factor Inhibits Apoptotic Pathways in Renal Cancer.

Serine and arginine rich splicing factor 2(SRSF2) belongs to the serine/arginine (SR)-rich family of proteins that regulate alternative splicing. Previous studies suggested that SRSF2 can contribute to carcinogenic processes. Clear cell renal cell carcinoma (ccRCC) is the most common subtype of kidney cancer, highly aggressive and difficult to treat, mainly due to resistance to apoptosis. In this study we hypothesized that SRSF2 contributes to the regulation of apoptosis in ccRCC. Using tissue samples obtained from ccRCC patients, as well as independent validation on The Cancer Genome Atlas (TCGA) data, we demonstrate for the first time that expression of SRSF2 is decreased in ccRCC tumours when compared to non-tumorous control tissues. Furthermore, by employing a panel of ccRCC-derived cell lines with silenced SRSF2 expression and qPCR arrays we show that SRSF2 contributes not only to splicing patterns but also to expression of multiple apoptotic genes, including new SRSF2 targets: DIABLO, BIRC5/survivin, TRAIL, BIM, MCL1, TNFRSF9, TNFRSF1B, CRADD, BCL2L2, BCL2A1, and TP53. We also identified a new splice variant of CFLAR, an inhibitor of caspase activity. These changes culminate in diminished caspase-9 activity and inhibition of apoptosis. In summary, we show for the first time that decreased expression of SRSF2 in ccRCC contributes to protection of cancer cells viability.

TGF-ß1 targets a microRNA network that regulates cellular adhesion and migration in renal cancer.

In our previous study we found altered expression of 19 adhesion-related genes in renal tumors. In this study we hypothesized that disturbed expression of adhesion-related genes could be caused by microRNAs: short, non-coding RNAs that regulate gene expression. Here, we found that expression of 24 microRNAs predicted to target adhesion-related genes was disturbed in renal tumors and correlated with expression of their predicted targets. miR-25-3p, miR-30a-5p, miR-328 and miR-363-3p directly targeted adhesion-related genes, including COL5A1, COL11A1, ITGA5, MMP16 and THBS2. miR-363-3p and miR-328 inhibited proliferation of renal cancer cells, while miR-25-3p inhibited adhesion, promoted proliferation and migration of renal cancer cells. TGF-ß1 influenced the expression of miR-25-3p, miR-30a-5p, and miR-328. The analyzed microRNAs, their target genes and TGF-ß1 formed a network of strong correlations in tissue samples from renal cancer patients. The expression signature of microRNAs linked with TGF-ß1 levels correlated with poor survival of renal cancer patients. The results of our study suggest that TGF-ß1 coordinates the expression of microRNA network that regulates cellular adhesion in cancer.

microRNAs target SRSF7 splicing factor to modulate the expression of osteopontin splice variants in renal cancer cells.

SRSF7 is a SR splicing factor involved in the regulation of splicing and mRNA export of cancer-related genes. The mechanisms regulating the expression of SRSF7 are unknown. This study shows that SRSF7 expression in cancer cells is regulated by microRNAs: short, non-coding RNAs that bind to 3'UTR of target genes and downregulate their expression. We show that microRNAs miR-30a-5p and miR-181a-5p together with SRSF7 form regulatory feedback loop in which the expression of microRNAs is recurrently regulated by its target. Finally, we demonstrate that silencing of SRSF7 affects the expression of osteopontin splice variants and decreases proliferation rate of renal cancer cells.