Dataset Information

Clinical significance of a point mutation in DNA polymerase beta (POLB) gene in gastric cancer.

ABSTRACT: Gastric cancer (GC) is a major cause of global cancer mortality. Genetic variations in DNA repair genes can modulate DNA repair capability and, consequently, have been associated with risk of developing cancer. We have previously identified a T to C point mutation at nucleotide 889 (T889C) in DNA polymerase beta (POLB) gene, a key enzyme involved in base excision repair in primary GCs. The purpose of this study was to evaluate the mutation and expression of POLB in a larger cohort and to identify possible prognostic roles of the POLB alterations in GC. Primary GC specimens and their matched normal adjacent tissues were collected at the time of surgery. DNA, RNA and protein samples were isolated from GC specimens and cell lines. Mutations were detected by PCR-RFLP/DHPLC and sequencing analysis. POLB gene expression was examined by RT-PCR, tissue microarray, Western blotting and immunofluorescence assays. The function of the mutation was evaluated by chemosensitivity, MTT, Transwell matrigel invasion and host cell reactivation assays. The T889C mutation was detected in 18 (10.17%) of 177 GC patients. And the T889C mutation was associated with POLB overexpression, lymph nodes metastases and poor tumor differentiation. In addition, patients with- the mutation had significantly shorter survival time than those without-, following postoperative chemotherapy. Furthermore, cell lines with T889C mutation in POLB gene were more resistant to the treatment of 5-fluorouracil, cisplatin and epirubicin than those with wild type POLB. Forced expression of POLB gene with T889C mutation resulted in enhanced cell proliferation, invasion and resistance to anticancer drugs, along with increased DNA repair capability. These results suggest that POLB gene with T889C mutation in surgically resected primary gastric tissues may be clinically useful for predicting responsiveness to chemotherapy in patients with GC. The POLB gene alteration may serve as a prognostic biomarker for GC.

SUBMITTER: Tan X

PROVIDER: S-EPMC4279090 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Clinical significance of a point mutation in DNA polymerase beta (POLB) gene in gastric cancer.

Tan Xiaohui X Wang Hongyi H Luo Guangbin G Ren Shuyang S Li Wenmei W Cui Jiantao J Gill Harindarpal S HS Fu Sidney W SW Lu Youyong Y

International journal of biological sciences 20150101 2

Gastric cancer (GC) is a major cause of global cancer mortality. Genetic variations in DNA repair genes can modulate DNA repair capability and, consequently, have been associated with risk of developing cancer. We have previously identified a T to C point mutation at nucleotide 889 (T889C) in DNA polymerase beta (POLB) gene, a key enzyme involved in base excision repair in primary GCs. The purpose of this study was to evaluate the mutation and expression of POLB in a larger cohort and to identif ...[more]

PMID: 25561897

Similar Datasets

Project description:Replicative DNA polymerases (Pols) frequently possess two distinct DNA processing activities: DNA synthesis (polymerization) and proofreading (3'-5' exonuclease activity). The polymerase and exonuclease reactions are performed alternately and are spatially separated in different protein domains. Thus, the growing DNA primer terminus has to undergo dynamic conformational switching between two distinct functional sites on the polymerase. Furthermore, the transition from polymerization (pol) mode to exonuclease (exo) mode must occur in the context of a DNA Pol holoenzyme, wherein the polymerase is physically associated with processivity factor proliferating cell nuclear antigen (PCNA) and primer-template DNA. The mechanism of this conformational switching and the role that PCNA plays in it have remained obscure, largely due to the dynamic nature of ternary Pol/PCNA/DNA assemblies. Here, we present computational models of ternary assemblies for archaeal polymerase PolB. We have combined all available structural information for the binary complexes with electron microscopy data and have refined atomistic models for ternary PolB/PCNA/DNA assemblies in pol and exo modes using molecular dynamics simulations. In addition to the canonical PIP-box/interdomain connector loop (IDCL) interface of PolB with PCNA, contact analysis of the simulation trajectories revealed new secondary binding interfaces, distinct between the pol and exo states. Using targeted molecular dynamics, we explored the conformational transition from pol to exo mode. We identified a hinge region between the thumb and palm domains of PolB that is critical for conformational switching. With the thumb domain anchored onto the PCNA surface, the neighboring palm domain executed rotational motion around the hinge, bringing the core of PolB down toward PCNA to form a new interface with the clamp. A helix from PolB containing a patch of arginine residues was involved in the binding, locking the complex in the exo mode conformation. Together, these results provide a structural view of how the transition between the pol and exo states of PolB is coordinated through PCNA to achieve efficient proofreading.

Dataset Information

Clinical significance of a point mutation in DNA polymerase beta (POLB) gene in gastric cancer.

Publications

Clinical significance of a point mutation in DNA polymerase beta (POLB) gene in gastric cancer.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure