1. Academic Validation
  2. Physical interaction between human ribonucleotide reductase large subunit and thioredoxin increases colorectal cancer malignancy

Physical interaction between human ribonucleotide reductase large subunit and thioredoxin increases colorectal cancer malignancy

  • J Biol Chem. 2017 Jun 2;292(22):9136-9149. doi: 10.1074/jbc.M117.783365.
Meng Lou 1 Qian Liu 1 Guoping Ren 2 Jiling Zeng 2 Xueping Xiang 3 Yongfeng Ding 4 Qinghui Lin 1 Tingting Zhong 1 Xia Liu 1 Lijun Zhu 5 Hongyan Qi 1 Jing Shen 1 Haoran Li 6 Jimin Shao 7
Affiliations

Affiliations

  • 1 From the Department of Pathology and Pathophysiology, Key Laboratory of Disease Proteomics of Zhejiang Province, Research Center for Air Pollution and Health, Zhejiang University School of Medicine, Hangzhou 310058, China.
  • 2 the Departments of Pathology and.
  • 3 the Department of Pathology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China, and.
  • 4 Surgical Oncology and.
  • 5 Key Laboratory of Precision Diagnosis and Treatment for Hepatobiliary and Pancreatic Tumor of Zhejiang Province, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China.
  • 6 Takeda Pharmaceuticals International Company, Cambridge, Massachusetts 02139.
  • 7 From the Department of Pathology and Pathophysiology, Key Laboratory of Disease Proteomics of Zhejiang Province, Research Center for Air Pollution and Health, Zhejiang University School of Medicine, Hangzhou 310058, China, shaojimin@zju.edu.cn.
Abstract

Ribonucleotide reductase (RR) is the rate-limiting Enzyme in DNA synthesis, catalyzing the reduction of ribonucleotides to deoxyribonucleotides. During each enzymatic turnover, reduction of the active site disulfide in the catalytic large subunit is performed by a pair of shuttle cysteine residues in its C-terminal tail. Thioredoxin (Trx) and glutaredoxin (Grx) are ubiquitous redox proteins, catalyzing thiol-disulfide exchange reactions. Here, immunohistochemical examination of clinical colorectal Cancer (CRC) specimens revealed that human thioredoxin1 (hTrx1), but not human glutaredoxin1 (hGrx1), was up-regulated along with human RR large subunit (RRM1) in Cancer tissues, and the expression levels of both proteins were correlated with Cancer malignancy stage. Ectopically expressed hTrx1 significantly increased RR activity, DNA synthesis, and cell proliferation and migration. Importantly, inhibition of both hTrx1 and RRM1 produced a synergistic Anticancer effect in CRC cells and xenograft mice. Furthermore, hTrx1 rather than hGrx1 was the efficient reductase for RRM1 regeneration. We also observed a direct protein-protein interaction between RRM1 and hTrx1 in CRC cells. Interestingly, besides the known two conserved cysteines, a third cysteine (Cys779) in the RRM1 C terminus was essential for RRM1 regeneration and binding to hTrx1, whereas both Cys32 and Cys35 in hTrx1 played a counterpart role. Our findings suggest that the up-regulated RRM1 and hTrx1 in CRC directly interact with each other and promote RR activity, resulting in enhanced DNA synthesis and Cancer malignancy. We propose that the RRM1-hTrx1 interaction might be a novel potential therapeutic target for Cancer treatment.

Keywords

colorectal cancer; enzyme catalysis; protein-protein interaction; ribonucleotide reductase; thioredoxin.

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