Inhibition of Twist1-mediated invasion by Chk2 promotes premature senescence in p53-defective cancer cells

Abstract

Twist1, a basic helix-loop-helix transcription factor is implicated as a key mediator of epithelial-mesenchymal transition (EMT) and metastatic dissemination in p53-deficient cancer cells. On the other hand, checkpoint kinase 2 (Chk2), a major cell cycle regulatory protein provides a barrier to tumorigenesis due to DNA damage response by preserving genomic stability of the cells. Here we demonstrate that Chk2 induction proficiently abrogates invasion, cell scattering and invadopodia formation ability of p53-mutated invasive cells by suppressing Twist1, indicating Chk2 confers vital role in metastasis prevention. In addition, ectopic Chk2, as well as its (Chk2) induction by natural podophyllotoxin analog, 4'-demethyl-deoxypodophyllotoxin glucoside (4DPG), strongly restrain Twist1 activity along with other mesenchymal markers, for example, ZEB-1, vimentin and Snail1, whereas the epithelial markers such as E-cadherin and TIMP-1 expression augmented robustly. However, downregulation of endogenous Chk2 by siRNA as well as Chk2 selective inhibitor PV1019 implies that 4DPG-mediated inhibition of Twist1 is Chk2-dependent. Further, mechanistic studies unveil that Chk2 negatively regulates Twist1 promoter activity and it (Chk2) interacts steadily with Snail1 protein to curb EMT. Strikingly, Chk2 overexpression triggers premature senescence in these cells with distinctive increase in senescence-associated β-galactosidase (SA-β-gal) activity, G2/M cell cycle arrest and induction of senescence-specific marker p21. Importantly, stable knockdown of Twist1 by shRNA markedly augments p21 expression, its nuclear accumulation, senescence-associated heterochromatin foci (SAHF) and amplifies the number of SA-β-gal-positive cells. Moreover, our in vivo studies also validate that 4DPG treatment significantly abrogates tumor growth as well as metastatic lung nodules formation by elevating the level of phospho-Chk2, Chk2 and suppressing Twist1 activity in mouse mammary carcinoma model. In a nutshell, this report conceives a novel strategy of Twist1 suppression through Chk2 induction, which prevents metastatic dissemination and promotes premature senescence in p53-defective invasive cancer cells.

Dihydropyrimidine dehydrogenase predicts survival and response to interferon-α in hepatocellular carcinoma

“…Then, by western blot screening and subsequent confirmatory assays, we identified that p38 is a novel target gene of DPYD in HCC, and could regulate NF-κB/Snail1 signaling in DPYD-induced EMT (Figs. 7 and 8 ) 23 , which is in concordance with the effects in other cell lines as previously reported 24 – 26 . However, the other EMT markers, such as vimentin, MMP2, and Twist1, were not observed to be involved in the DPYD-mediated EMT in HCC.…”

Senescence Induction by Combined Ionizing Radiation and DNA Damage Response Inhibitors in Head and Neck Squamous Cell Carcinoma Cells

“…Various therapies aim to restore the capacity to senesce in cancer cells. As an example, overexpression of Chk2 was found to help restore senescence in some p53-deficient cancer cells [ 18 , 45 ]. In line with this finding, inhibition of ATR/ATM or Chk1/Chk2 was found to delay the onset of replicative senescence [ 24 ].…”

Anticancer effects of oridonin on colon cancer are mediated via BMP7/p38 MAPK/p53 signaling

“…The downregulation of p53 (a vital tumor suppressor) is a primary causative factor for colon cancer. The mutation or functional loss of p53 have been identified in >50% of human tumor cells (43,44). Stress can activate the p35 signal, such as p38 MAPK (21).…”