The functions of long noncoding RNAs (lncRNAs) have been identified in several cancers, but the roles of lncRNAs in colorectal cancer (CRC) are less well understood. The transcription factor MYC is known to regulate lncRNAs and has been implicated in cancer cell proliferation and tumorigenesis. CRC cells and tissues were profiled to identify lncRNAs differentially expressed in CRC, from which we further selected MYC-regulated lncRNAs. We used luciferase promoter assay, ChIP, RNA pull-down assay, deletion mapping assay, LC-MS/MS and RNA immunoprecipitation to determine the mechanisms of MYC regulation of lncRNAs. Moreover, soft agar assay and in vivo xenograft experiments (four athymic nude mice per group) provided evidence of MYC-regulated lncRNAs in cancer cell transformation and tumorigenesis. The Kaplan-Meier method was used for survival analyses. All statistical tests were two-sided. We identified lncRNAs differentially expressed in CRC (P < .05, greater than two-fold) and verified four lncRNAs upregulated and two downregulated in CRC cells and tissues. We further identified MYC-regulated lncRNAs, named MYCLos. The MYC-regulated MYCLos may function in cell proliferation and cell cycle by regulating MYC target genes such as CDKN1A (p21) and CDKN2B (p15), suggesting new regulatory mechanisms of MYC-repressed target genes through lncRNAs. RNA binding proteins including HuR and hnRNPK are involved in the function of MYCLos by interacting with MYCLo-1 and MYCLo-2, respectively. Knockdown experiments also showed that MYCLo-2, differentially expressed not only in CRC but also in prostate cancer, has a role in cancer transformation and tumorigenesis. Our results provide novel regulatory mechanisms in MYC function through lncRNAs and new potential lncRNA targets of CRC.

Lung cancer is the leading cause of cancer-related deaths worldwide and non-small cell lung cancer (NSCLC) accounts for over 80% of lung cancer cases. The RNA binding protein, QKI, belongs to the STAR family and plays tumor-suppressive functions in NSCLC. QKI-5 is a major isoform of QKIs and is predominantly expressed in NSCLC. However, the underlying mechanisms of QKI-5 in NSCLC progression remain unclear. We found that QKI-5 regulated microRNA (miRNA), miR-196b-5p, and its expression was significantly up-regulated in NSCLC tissues. Up-regulated miR-196b-5p promotes lung cancer cell migration, proliferation, and cell cycle through directly targeting the tumor suppressors, GATA6 and TSPAN12. Both GATA6 and TSPAN12 expressions were down-regulated in NSCLC patient tissue samples and were negatively correlated with miR-196b-5p expression. Mouse xenograft models demonstrated that miR-196b-5p functions as a potent onco-miRNA, whereas TSPAN12 functions as a tumor suppressor in NSCLC in vivo. QKI-5 bound to miR-196b-5p and influenced its stability, resulting in up-regulated miR-196b-5p expression in NSCLC. Further analysis showed that hypomethylation in the promoter region enhanced miR-196b-5p expression in NSCLC. Our findings indicate that QKI-5 may exhibit novel anticancer mechanisms by regulating miRNA in NSCLC, and targeting the QKI5∼miR-196b-5p∼GATA6/TSPAN12 pathway may enable effectively treating some NSCLCs.

Significance: Many cancer-associated variants have been found in the 8q24.21 region harboring enhancer activity. However, the functional mechanism of the variants is not clear due to the lack of protein-coding genes in the region and no significant correlation with the nearest oncogene MYC . We identified long noncoding RNAs (lncRNAs) named cancer-associated region long noncoding RNAs ( CARLo s) in the 8q24.21 region. Interestingly, we found that the cancer-associated variant rs6983267 regulating the enhancer activity is significantly associated with the expression of one of the lncRNAs CARLo-5 and that CARLo-5 has an oncogenic function. By showing direct interaction between the enhancer region and active regulatory region of the CARLo-5 promoter, we provide a regulatory mechanism of cancer susceptibility caused by the cancer-associated variants.

MicroRNAs (miRNAs) are small 19- to 24-nt noncoding RNAs that have the capacity to regulate fundamental biological processes essential for cancer initiation and progression. In cancer, miRNAs may function as oncogenes or tumor suppressors. Here, we conducted global profiling for miRNAs in a cohort of stage 1 nonsmall cell lung cancers ( n = 81) and determined that miR-486 was the most down-regulated miRNA in tumors compared with adjacent uninvolved lung tissues, suggesting that miR-486 loss may be important in lung cancer development. We report that miR-486 directly targets components of insulin growth factor (IGF) signaling including insulin-like growth factor 1 (IGF1), IGF1 receptor (IGF1R), and phosphoinositide-3-kinase, regulatory subunit 1 (alpha) (PIK3R1, or p85a) and functions as a potent tumor suppressor of lung cancer both in vitro and in vivo. Our findings support the role for miR-486 loss in lung cancer and suggest a potential biological link to p53.

Significance: Aberrant microRNA (miRNA) expression is involved in tumorigenesis, and miR-224 was observed to be up-regulated in certain tumor types. However, the role of miR-224 in the pathogenesis of lung cancer remains poorly understood. Here, we comprehensively analyzed and revealed mechanisms of miR-224 up-regulation and its oncogenic role in nonsmall cell lung cancer (NSCLC). We showed that miR-224 promotes cellular migratory, invasive, and proliferative capacity and tumor growth both in vitro and in vivo. Furthermore, we identified TNFα-induced protein 1 and SMAD4 as targets of miR-224 . In addition, up-regulated miR-224 expression in NSCLC is partially controlled by its promoter region’s hypomethylation and activated ERK signaling. Our finding suggests that targeting miR-224 might be a promising therapeutic strategy in the treatment of NSCLC.