Non-coding RNAs in Precursor Lesions of Colorectal Cancer: Their Role in Cancer Initiation and Formation

RNA splicing variants of the novel long non-coding RNA, CyKILR, possess divergent biological functions in non-small cell lung cancer

The CDKN2A gene, responsible for encoding the tumor suppressors p16(INK4A) and p14(ARF), is frequently inactivated in non-small cell lung cancer (NSCLC). Herein, an uncharacterized long non-coding RNA (lncRNA) (ENSG00000267053) on chromosome 19p13.12 was found to be overexpressed in NSCLC cells with an active, wild-type CDKN2A gene. This lncRNA, named cyclin-dependent kinase inhibitor 2A-regulated lncRNA (CyKILR), also correlated with an active WT STK11 gene, which encodes the tumor suppressor, liver kinase B1. CyKILR displayed two splice variants, CyKILRa (exon 3 included) and CyKILRb (exon 3 excluded), which are cooperatively regulated by CDKN2A and STK11 as knockdown of both tumor suppressor genes was required to induce a significant loss of exon 3 inclusion in mature CyKILR RNA. CyKILRa localized to the nucleus, and its downregulation using antisense RNA oligonucleotides enhanced cellular proliferation, migration, clonogenic survival, and tumor incidence. In contrast, CyKILRb localized to the cytoplasm, and its downregulation using small interfering RNA reduced cell proliferation, migration, clonogenic survival, and tumor incidence. Transcriptomics analyses revealed the enhancement of apoptotic pathways with concomitant suppression of key cell-cycle pathways by CyKILRa demonstrating its tumor-suppressive role. CyKILRb inhibited tumor suppressor miRNAs indicating an oncogenic nature. These findings elucidate the intricate roles of lncRNAs in cell signaling and tumorigenesis.

RNA splicing variants of the novel long non-coding RNA, CyKILR, possess divergent biological functions in non-small cell lung cancer

The CDKN2A gene, responsible for encoding the tumor suppressors p16(INK4A) and p14(ARF), is frequently inactivated in non-small cell lung cancer (NSCLC). Herein, an uncharacterized long non-coding RNA (lncRNA) (ENSG00000267053) on chromosome 19p13.12 was found to be overexpressed in NSCLC cells with an active, wild-type CDKN2A gene. This lncRNA, named Cy clin-Dependent K inase I nhibitor 2A-regulated l nc R NA (CyKILR), also correlated with an active WT STK11 gene, which encodes the tumor suppressor, Liver kinase B1. CyKILR displayed two splice variants, CyKILRa (exon 3 included) and CyKILRb (exon 3 excluded), which are cooperatively regulated by CDKN2A and STK11 as knockdown of both tumor suppressor genes was required to induce a significant loss of exon 3 inclusion in mature CyKILR RNA. CyKILRa localized to the nucleus, and its downregulation using antisense RNA oligonucleotides enhanced cellular proliferation, migration, clonogenic survival, and tumor incidence. In contrast, CyKILRb localized to the cytoplasm, and its downregulation using siRNA reduced cell proliferation, migration, clonogenic survival, and tumor incidence. Transcriptomics analyses revealed enhancement of apoptotic pathways with concomitant suppression of key cell cycle pathways by CyKILRa demonstrating its tumor-suppressive role. CyKILRb inhibited tumor suppressor microRNAs indicating an oncogenic nature. These findings elucidate the intricate roles of lncRNAs in cell signaling and tumorigenesis.

The implication of TET1, miR-200, and miR-494 expression with tumor formation in colorectal cancer: through targeting Wnt signaling

OBJECTIVE

Colorectal cancer (CRC) is a diverse and multifaceted disease characterized by genetic and epigenetic changes that contribute to tumor initiation and progression. CRC pathophysiology has been linked to the deregulation of the Wnt signaling pathway and the ten-eleven translocation (TET) DNA demethylases. This study aimed to evaluate the expression level of selective miRNAs (miR-200 and miR-494), TET1, and Wnt1 in colorectal polyps, actual colorectal tumors, and normal adjacent tissues. We also evaluated the effect of 5-aza cytidine on the expression level of TET1 and wnt1 in the HT29 cell line.

MATERIALS AND METHODS

In this study, we assessed TET1 and Wnt1 expression in 5-azacytidine-treated HT29 cells, a demethylating agent commonly used in cancer therapy. Additionally, we enrolled 114 individuals who underwent radical surgical colon resection, including 47 with cancerous tissues and 67 with polyps. We utilized qRT-PCR to measure miR-200, miR-494, TET1, and Wnt1 mRNA levels in colorectal polyps, actual colorectal tumors, and normal adjacent tissues.

RESULTS

Our study revealed that TET1 expression was notably lower in both polyps and CRC tissue compared to adjacent normal tissue, with higher TET1 expression in tumors than polyps. We also observed significant differences in miR-200 and miR-494 expression in tumor samples compared to adjacent normal tissue. Our in vitro experiments revealed that 5-azacytidine administration increased TET1 and decreased Wnt1 expression in CRC cell lines. This suggests that DNA-demethylating drugs may have a therapeutic role in modifying TET1 and Wnt signaling in the development of CRC.

CONCLUSIONS

Overall, our findings shed light on the intricate interactions between TET1, Wnt1, and specific miRNAs in colorectal cancer (CRC) and their potential implications for diagnosis and treatment.