Journal Article

ERK-mediated TIMELESS expression suppresses G2/M arrest in colon cancer cells

Neilsen, Beth K., Fisher, Kurt W., Frodyma, Danielle E., Lewis, Robert E., McCall, Jamie L.

2019

Overview

The cell cycle is under circadian regulation. Oncogenes can dysregulate circadian-regulated genes to disrupt the cell cycle, promoting tumor cell proliferation. As a regulator of G2/M arrest in response to DNA damage, the circadian gene Timeless Circadian Clock (TIMELESS) coordinates this connection and is a potential locus for oncogenic manipulation. TIMELESS expression was evaluated using RNASeq data from TCGA and by RT-qPCR and western blot analysis in a panel of colon cancer cell lines. TIMELESS expression following ERK inhibition was examined via western blot. Cell metabolic capacity, propidium iodide, and CFSE staining were used to evaluate the effect of TIMELESS depletion on colon cancer cell survival and proliferation. Cell metabolic capacity following TIMELESS depletion in combination with Wee1 or CHK1 inhibition was assessed. TIMELESS is overexpressed in cancer and required for increased cancer cell proliferation. ERK activation promotes TIMELESS expression. TIMELESS depletion increases γH2AX, a marker of DNA damage, and triggers G2/M arrest via increased CHK1 and CDK1 phosphorylation. TIMELESS depletion in combination with Wee1 or CHK1 inhibition causes an additive decrease in cancer cell metabolic capacity with limited effects in non-transformed human colon epithelial cells. The data show that ERK activation contributes to the overexpression of TIMELESS in cancer. Depletion of TIMELESS increases γH2AX and causes G2/M arrest, limiting cell proliferation. These results demonstrate a role for TIMELESS in cancer and encourage further examination of the link between circadian rhythm dysregulation and cancer cell proliferation.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Biology / Biology and Life Sciences / Breast cancer / Cancer / Cancer cells / CDC2 Protein Kinase - metabolism / Cell activation / Cell cycle / Cell Cycle Proteins - antagonists & inhibitors / Cell Cycle Proteins - genetics / Cell Cycle Proteins - metabolism / Cell growth / Cell Line, Tumor / Cell Proliferation / Cell survival / Checkpoint Kinase 1 - antagonists & inhibitors / Checkpoint Kinase 1 - metabolism / CHK1 protein / Circadian rhythm / Circadian rhythms / Colon / Colon cancer / Colonic Neoplasms - genetics / Colonic Neoplasms - metabolism / Colonic Neoplasms - pathology / Colorectal cancer / Deoxyribonucleic acid / Depletion / DNA / DNA Damage / Epithelial cells / Extracellular signal-regulated kinase / Fibroblasts / G2 Phase Cell Cycle Checkpoints - genetics / G2 Phase Cell Cycle Checkpoints - physiology / Gene expression / Gene Expression Regulation, Neoplastic / Genomes / HCT116 Cells / Histones - metabolism / Humans / Inhibition / Intracellular Signaling Peptides and Proteins - antagonists & inhibitors / Intracellular Signaling Peptides and Proteins - genetics / Intracellular Signaling Peptides and Proteins - metabolism / Iodides / Kinases / MAP Kinase Signaling System / Medical research / Medicine and Health Sciences / Nuclear Proteins - antagonists & inhibitors / Oncogenes / Phosphorylation / Propidium iodide / Protein-Tyrosine Kinases - antagonists & inhibitors / RNA, Small Interfering - genetics / Timeless protein / Tumor cell lines / Tumors / Virology