Activation of PERK Contributes to Apoptosis and G2/M Arrest by Microtubule Disruptors in Human Colorectal Carcinoma Cells

Ming-Shun Wu,Yen-Chou Chen,Chih-Chiang Chien,Ganbolor Jargalsaikhan,Noor Andryan Ilsan

doi:10.3390/cancers12010097

Abstract

Microtubule-targeting agents (MTAs) are widely used in cancer chemotherapy, but the therapeutic responses significantly vary among different tumor types. Protein kinase RNA-like endoplasmic reticular (ER) kinase (PERK) is an ER stress kinase, and the role of PERK in the anticancer effects of MTAs is still undefined. In the present study, taxol (TAX) and nocodazole (NOC) significantly induced apoptosis with increased expression of phosphorylated PERK (pPERK; Tyr980) in four human colon cancer cell lines, including HCT-15, COLO205, HT-20, and LOVO cells. Induction of G2/M arrest by TAX and NOC with increases in phosphorylated Cdc25C and cyclin B1 protein were observed in human colon cancer cells. Application of the c-Jun N-terminal kinase (JNK) inhibitors SP600125 (SP) and JNK inhibitor V (JNKI) significantly reduced TAX- and NOC-induced apoptosis and G2/M arrest of human colon cancer cells. Interestingly, TAX- and NOC-induced pPERK (Tyr980) protein expression was inhibited by adding the JNK inhibitors, SP and JNKI, and application of the PERK inhibitor GSK2606414 (GSK) significantly reduced apoptosis and G2/M arrest by TAX and NOC, with decreased pPERK (Tyr980) and pJNK, phosphorylated Cdc25C, and Cyc B1 protein expressions in human colon cancer cells. Decreased viability by TAX and NOC was inhibited by knockdown of PERK using PERK siRNA in COLO205 and HCT-15 cells. Disruption of the mitochondrial membrane potential and an increase in B-cell lymphoma-2 (Bcl-2) protein phosphorylation (pBcl-2; Ser70) by TAX and NOC were prevented by adding the PERK inhibitor GSK and JNK inhibitor SP and JNKI. A cross-activation of JNK and PERK by TAX and NOC leading to anti-CRC actions including apoptosis and G2/M arrest was first demonstrated herein.

Highlights

Colorectal cancer (CRC) is the third most common diagnosis and second deadliest malignancy for both sexes combined [1]
We first examined the effect of two Microtubule-targeting agents (MTAs) (TAX and NOC) on the viability of four human CRC cell lines, including COLO205, HCT-15, LOVO, and HT-29 cells
We found a cross-activation between Jun N-terminal kinase (JNK) and PERK leading to apoptosis and G2 /M arrest by TAX and NOC in human CRC cells

Summary

Introduction

Colorectal cancer (CRC) is the third most common diagnosis and second deadliest malignancy for both sexes combined [1]. Many therapeutic strategies, such as surgery, chemotherapy, and radiotherapy, are used to treat CRC, and radiotherapy combined with chemotherapy is the standard of care in locally advanced rectal cancer in the setting of neoadjuvant treatment, but the outcome remains suboptimal for advanced cases. PD-1 inhibitors, nivolumab, and pembrolizumab, which currently constitute the new standard of care as treatment of chemotherapy-refractory microsatellite-instability-high (MSI-high)/mismatch repair-deficient (MMR-d) CRC. Microtubule-targeting agents (MTAs) were developed to induce stabilization or destabilization of microtubules, leading to blockage of the deregulated mitotic process and induction of apoptosis of cancer cells, and have been extensively used in clinical cancer treatment [5,6]. MTAs have been applied as cancer therapeutics for several decades, drug resistance is one of the key factors obstructing the clinical applicability of MTAs

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