Microsatellite instability in human mammary epithelial cells transformed by heavy ions.
We analyzed DNA and proteins obtained from normal and transformed human mammary epithelial cells for studying the neoplastic transformation by high-LET irradiation in vitro. We also examined microsatellite instability in human mammary cells transformed to various stages of carcinogenesis, such as normal, growth variant and tumorigenic, using microsatellite marker D5S177 on the chromosome 5 and CYl7 on the Chromosome 10. Microsatellite instabilities were detected in the tumorigenic stage. These results suggest that microsatellite instability may play a role in the progression of  tumorigenecity. The cause of the genomic instability has been suggested as abnormalities of DNA-repair systems which may be due to one of the three reasons: 1) alterations of cell cycle regulating genes. 2) mutations in any of the DNA mismatch repair genes, 3) mutation in any of the DNA strand breaks repair genes. No abnormality of these genes and encoded proteins, however was found in the present studies. These studies thus suggest that the microsatellite instability is induced by an alternative mechanism.
Yamada
S
S
Research Center of Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
Yang
T C
TC
George
K
K
Okayasu
R
R
Ando
K
K
Tsujii
H
H
D001940:Breast / Q000166:cytology / Q000473:pathology / Q000528:radiation effects; D002453:Cell Cycle / Q000235:genetics*; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic; D004249:DNA Damage; D004260:DNA Repair / Q000235:genetics*; D004847:Epithelial Cells / Q000166:cytology / Q000473:pathology / Q000528:radiation effects; D018816:Genes, cdc / Q000528:radiation effects*; D020450:Heavy Ions; D006801:Humans; D007501:Iron; D018499:Linear Energy Transfer; D018895:Microsatellite Repeats; D009154:Mutation
D007501:Iron