Involvement of DNA polymerase beta overexpression in the malignant transformation induced by benzo[a]pyrene

Abstract

Objective To explore the relationship between DNA polymerase β (pol β) overexpression and benzo[a]pyrene (BaP) carcinogenesis. Methods Firstly, mouse embryonic fibroblasts that express wild-type level of DNA polymerase β (pol β cell) and high level of pol β (pol β oe cell) were treated by various concentrations of BaP to determine genetic instability induced by BaP under differential expression levels of pol β. Secondly, malignant transformation of pol β cells by low concentration of BaP (20 μM) was determined by soft agar colony formation assay and transformation focus assay. Thirdly, the mRNA and protein levels of BaP-transformed pol β cells (named pol β-T cells) was measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blot, and the genetic instability of these cells were examined by HPRT gene mutation assay and random amplified polymorphic DNA (RAPD) assay. Results Pol β cells were successfully transformed into malignant pol β-T cells by an exposure to low concentration of BaP for 6 months. Pol β-T cells exhibited increased levels of pol β gene expression, HPRT gene mutation frequency and polymorphisms of RAPD products that were comparable to those of pol β oe cells. Conclusion Pol β overexpression and its-associated genetic instability may play a key role in BaP carcinogenesis.

A High Throughput Micro-Chamber Array Device for Single Cell Clonal Cultivation and Tumor Heterogeneity Analysis

“…Series of events occurred during the fission and clonal proliferation of single cells, through which some of the cells survived and acquired preponderant characteristics over other cells, then heterogeneity happened 6 . Single cell isolation and clonal cultivation pave ways for tumor heterogeneity researches 7 8 9 10 11 12 13 14 15 . Traditional single cell cloning techniques including limiting dilution cloning, feeder layer cloning, agar cloning have made great contribution to tumor cell heterogeneity studies.…”