Role of MYC-regulated long noncoding RNAs in cell cycle regulation and tumorigenesis.

Abstract

BACKGROUND:

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.

METHODS:

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.

RESULTS:

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.

CONCLUSIONS:

Our results provide novel regulatory mechanisms in MYC function through lncRNAs and new potential lncRNA targets of CRC.

• Authors: Taewan Kim, Young-Jun Jeon, Ri Cui, Ji-Hoon Lee, Yong Peng, Sung-Hak Kim, Esmerina Tili, Hansjuerg Alder, Carlo M Croce
• Journal: Journal of the National Cancer Institute (J Natl Cancer Inst) Vol. 107 Issue 4 (Apr 2015) ISSN: 1460-2105 [Electronic] United States
• PMID: 25663692 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)
• Copyright: © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: [email protected].

Chemical References

• CDKN1A protein, human
• CDKN2B protein, human
• Cell Cycle Proteins
• Cyclin-Dependent Kinase Inhibitor p15
• Cyclin-Dependent Kinase Inhibitor p21
• ELAV Proteins
• Heterogeneous-Nuclear Ribonucleoprotein K
• MYC protein, human
• Proto-Oncogene Proteins c-myc
• RNA, Long Noncoding
• Ribonucleoproteins
• HNRNPK protein, human

Topics

• Animals
• Carcinogenesis
• Cell Cycle Proteins (genetics, metabolism)
• Cell Proliferation
• Cell Transformation, Neoplastic (genetics, metabolism)
• Colorectal Neoplasms (genetics, metabolism, mortality)
• Cyclin-Dependent Kinase Inhibitor p15 (genetics, metabolism)
• Cyclin-Dependent Kinase Inhibitor p21 (genetics, metabolism)
• ELAV Proteins (metabolism)
• Flow Cytometry
• Gene Amplification
• Gene Expression Regulation, Neoplastic
• Heterogeneous-Nuclear Ribonucleoprotein K
• Heterografts
• Humans
• Immunoprecipitation
• Kaplan-Meier Estimate
• Mice
• Mice, Nude
• Proto-Oncogene Proteins c-myc (genetics, metabolism)
• RNA, Long Noncoding (metabolism)
• Real-Time Polymerase Chain Reaction
• Ribonucleoproteins (metabolism)