TY - JOUR
T1 - Adenomatous polyposis coli-mediated hypersensitivity of mouse embryonic fibroblast cell lines to methylmethane sulfonate treatment
T2 - Implication of base excision repair pathways
AU - Kundu, Chanakya N.
AU - Balusu, Ramesh
AU - Jaiswal, Aruna S.
AU - Narayan, Satya
PY - 2007/10
Y1 - 2007/10
N2 - The role of adenomatous polyposis coli (APC) has been implicated in various cellular functions including cell migration, cell-cell adhesion, cell cycle control, chromosomal segregation and apoptosis. Recently, we discovered a novel role of APC in DNA base excision repair (BER) and showed that APC interacts with DNA polymerase β (Pol-β) and flap endonuclease 1 and interferes long-patch base excision repair (LP-BER) by blocking strand displacement synthesis. Many times, the chemotherapeutic drugs induce DNA alkylation damage, which is primarily repaired by the BER pathway. Thus, the efficacy of such drugs can be increased by APC resulting in the blockage of LP-BER. In the present study, we tested this hypothesis by using isogenic wild-type and Pol-β-knockout mouse embryonic fibroblast (MEF) cell lines in which the Apc gene was knocked down by the small interfering RNA technique and treated with methylmethane sulfonate (MMS). The MEF- Apc(WT)/Polβ-/- cells were hypersensitive to MMS treatment compared with the MEF- Apc(WT)/Polβ+/+ cells. However, once the Apc gene was knocked down, these cells became more resistant to MMS treatment, suggesting that the MMS-induced hypersensitivity was associated with Apc. We then determined whether the hypersensitivity of MEF- Apc(WT)/Polβ-/- and MEF- Apc(WT)/Polβ+/+ cell lines were due to decreased Pol-β-independent and Pol-β-dependent LP-BER pathways, respectively. The results of in vivo and in vitro LP-BER assays supported our findings. Furthermore, Apc-mediated hypersensitivity to MMS treatment was correlated with increased apoptosis of MEF- Apc(WT)/ Polβ-/- and MEF- Apc(WT)/Polβ-/- as compared with MEF- Apc(KD)/Polβ-/- and MEF- Apc(KD)/ Polβ+/+ cells. These results suggest that an increased level of Apc can increase the efficacy of DNA-alkylating drugs used as a curative therapy.
AB - The role of adenomatous polyposis coli (APC) has been implicated in various cellular functions including cell migration, cell-cell adhesion, cell cycle control, chromosomal segregation and apoptosis. Recently, we discovered a novel role of APC in DNA base excision repair (BER) and showed that APC interacts with DNA polymerase β (Pol-β) and flap endonuclease 1 and interferes long-patch base excision repair (LP-BER) by blocking strand displacement synthesis. Many times, the chemotherapeutic drugs induce DNA alkylation damage, which is primarily repaired by the BER pathway. Thus, the efficacy of such drugs can be increased by APC resulting in the blockage of LP-BER. In the present study, we tested this hypothesis by using isogenic wild-type and Pol-β-knockout mouse embryonic fibroblast (MEF) cell lines in which the Apc gene was knocked down by the small interfering RNA technique and treated with methylmethane sulfonate (MMS). The MEF- Apc(WT)/Polβ-/- cells were hypersensitive to MMS treatment compared with the MEF- Apc(WT)/Polβ+/+ cells. However, once the Apc gene was knocked down, these cells became more resistant to MMS treatment, suggesting that the MMS-induced hypersensitivity was associated with Apc. We then determined whether the hypersensitivity of MEF- Apc(WT)/Polβ-/- and MEF- Apc(WT)/Polβ+/+ cell lines were due to decreased Pol-β-independent and Pol-β-dependent LP-BER pathways, respectively. The results of in vivo and in vitro LP-BER assays supported our findings. Furthermore, Apc-mediated hypersensitivity to MMS treatment was correlated with increased apoptosis of MEF- Apc(WT)/ Polβ-/- and MEF- Apc(WT)/Polβ-/- as compared with MEF- Apc(KD)/Polβ-/- and MEF- Apc(KD)/ Polβ+/+ cells. These results suggest that an increased level of Apc can increase the efficacy of DNA-alkylating drugs used as a curative therapy.
UR - http://www.scopus.com/inward/record.url?scp=35148859739&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=35148859739&partnerID=8YFLogxK
U2 - 10.1093/carcin/bgm125
DO - 10.1093/carcin/bgm125
M3 - Article
C2 - 17522063
AN - SCOPUS:35148859739
SN - 0143-3334
VL - 28
SP - 2089
EP - 2095
JO - Carcinogenesis
JF - Carcinogenesis
IS - 10
ER -