TY - JOUR
T1 - Mismatch repair deficiency
T2 - A temozolomide resistance factor in medulloblastoma cell lines that is uncommon in primary medulloblastoma tumours
AU - Von Bueren, A. O.
AU - Bacolod, M. D.
AU - Hagel, C.
AU - Heinimann, K.
AU - Fedier, A.
AU - Kordes, U.
AU - Pietsch, T.
AU - Koster, J.
AU - Grotzer, M. A.
AU - Friedman, H. S.
AU - Marra, G.
AU - Kool, M.
AU - Rutkowski, S.
N1 - Funding Information:
We would like to thank Dr Bert Vogelstein, Dr Josef Jiricny, and Dr Stefan M Pfister for helpful comments. We thank Dr Darell D Bigner for kindly providing D283Med cells. We are grateful to Dr Udo zur Stadt and Guido Looft for some assistance in sequencing experiments. Temozolomide was a generous gift of Schering-Plough (Kenilworth, NJ). We acknowledge the following sources of funding: The Swiss Research Foundation Child and Cancer (AOVB, MAG), German Children’s Cancer Foundation/ Deutsche Kinderkrebsstiftung (AOVB, SR, TP), Krebsliga Zürich (GM), Krebsliga beider Basel (KH), Oncosuisse (KH), German Research Foundation (TP) and Fördergemeinschaft Kinderkrebs-zentrum Hamburg e. V. (AOVB, SR).
PY - 2012/10/9
Y1 - 2012/10/9
N2 - Background: Tumours are responsive to temozolomide (TMZ) if they are deficient in O6-methylguanine-DNA methyltransferase (MGMT), and mismatch repair (MMR) proficient. Methods: The effect of TMZ on medulloblastoma (MB) cell killing was analysed with clonogenic survival assays. Expression of DNA repair genes and enzymes was investigated using microarrays, western blot, and immunohistochemistry. DNA sequencing and promoter methylation analysis were employed to investigate the cause of loss of the expression of MMR gene MLH1. Results: Temozolomide exhibited potent cytotoxic activity in D425Med (MGMT deficient, MLH1 proficient; IC50 1.7 μM), moderate activity against D341Med (MGMT proficient, MLH1 deficient), and DAOY MB cells (MGMT proficient, MLH1 proficient). MGMT inhibitor O6-benzylguanine sensitised DAOY, but not D341Med cells to TMZ. Of 12 MB cell lines, D341Med, D283Med, and 1580WÜ cells exhibited MMR deficiency due to MLH1 promoter hypermethylation. DNA sequencing of these cells provided no evidence for somatic genetic alterations in MLH1. Expression analyses of MMR and MGMT in MB revealed that all patient specimens (n74; expression array, n61; immunostaining, n13) are most likely MMR proficient, whereas some tumours had low MGMT expression levels (according to expression array) or were totally MGMT deficient (3 out of 13 according to immunohistochemistry). Conclusion: A subset of MB may respond to TMZ as some patient specimens are MGMT deficient, and tumours appear to be MMR proficient.
AB - Background: Tumours are responsive to temozolomide (TMZ) if they are deficient in O6-methylguanine-DNA methyltransferase (MGMT), and mismatch repair (MMR) proficient. Methods: The effect of TMZ on medulloblastoma (MB) cell killing was analysed with clonogenic survival assays. Expression of DNA repair genes and enzymes was investigated using microarrays, western blot, and immunohistochemistry. DNA sequencing and promoter methylation analysis were employed to investigate the cause of loss of the expression of MMR gene MLH1. Results: Temozolomide exhibited potent cytotoxic activity in D425Med (MGMT deficient, MLH1 proficient; IC50 1.7 μM), moderate activity against D341Med (MGMT proficient, MLH1 deficient), and DAOY MB cells (MGMT proficient, MLH1 proficient). MGMT inhibitor O6-benzylguanine sensitised DAOY, but not D341Med cells to TMZ. Of 12 MB cell lines, D341Med, D283Med, and 1580WÜ cells exhibited MMR deficiency due to MLH1 promoter hypermethylation. DNA sequencing of these cells provided no evidence for somatic genetic alterations in MLH1. Expression analyses of MMR and MGMT in MB revealed that all patient specimens (n74; expression array, n61; immunostaining, n13) are most likely MMR proficient, whereas some tumours had low MGMT expression levels (according to expression array) or were totally MGMT deficient (3 out of 13 according to immunohistochemistry). Conclusion: A subset of MB may respond to TMZ as some patient specimens are MGMT deficient, and tumours appear to be MMR proficient.
KW - Drug resistance
KW - Medulloblastoma
KW - Mismatch repair
KW - Temozolomide
UR - http://www.scopus.com/inward/record.url?scp=84867397241&partnerID=8YFLogxK
U2 - 10.1038/bjc.2012.403
DO - 10.1038/bjc.2012.403
M3 - Article
C2 - 22976800
AN - SCOPUS:84867397241
SN - 0007-0920
VL - 107
SP - 1399
EP - 1408
JO - British Journal of Cancer
JF - British Journal of Cancer
IS - 8
ER -