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[Inhibitory effect of all-trans-retinoid and polyphenon-100 on microsatellite instability in a colon cancer line]
Jian Ye1, Hua Lu, Jianwei Zhou
1Institute of Applied Toxicology, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, 210029 P. R. China. yejian89@hotmail.com
Objective:
To investigate the effects of all-trans-retinoic acid(ATRA) and polyphenon-100 (PP) on genetic instability of human tumor cells via their role in alteration of microsatellite sequence(MS) and the expression of mismatch repair gene hMLH(1) and hMSH(2) in RER(+) (replication error) cells.
Methods:
RER(+) colon cancer cell line was used as a host for lipofection with pCMV-CAR in which a foreign (CA)(14) repeat was inserted in the coding sequence of LacZ reporter gene, resulting in misreading LacZ frame. Any mutation which made the base number of (CA)(14) tract to be 3-fold resumed normal reading frame of LacZ, and thus led to expression of beta-galactosidase. Variable expression of LacZ in the transfectant cells resulting from RATA or PP treatment was measured by OD reading at lambda 620 after X-gal staining. Expression of mismatch repair genes of hMLH(1) and hMSH(2) was examined at mRNA level by reverse transcription-polymerase chain reaction (RT-PCR).
Results:
ATRA at 1 mu mol/L, 0.1 u mol/L and PP at 3 mu g/ml had no significant inhibitory effect on cell proliferation. After being treated with ATRA or PP for 1 week, the blue cells of RKO transfectant clones were significantly reduced, and this meant the mutation of exogenous (CA)(14) in RKO cells were inhibited. But no expression of hMLH(1) and hMSH(2) was observed.
Conclusion:
The above data showed both ATRA and PP had inhibitory effects on MS instability of cancer and thus demonstrated directly their beneficial role in stabilization of genomic DNA. However, the present authors have not observed any expression of hMLH(1) and hMSH(2) in RKO cells treated with ATRA or PP.
Insights
All-trans-retinoic acid (ATRA) and polyphenon-100 (PP) reduce microsatellite instability in cancer cells. These compounds stabilize genomic DNA but did not affect mismatch repair gene expression in RER(+) cells.
Area of Science:
- Genetics
- Molecular Biology
- Cancer Research
Background:
- Microsatellite (MS) instability is a hallmark of many cancers.
- Replication error (RER)(+) cells exhibit heightened genetic instability.
- Understanding agents that can modulate MS instability is crucial for cancer therapy.
Purpose of the Study:
- To evaluate the impact of all-trans-retinoic acid (ATRA) and polyphenon-100 (PP) on genetic instability.
- To investigate their effects on microsatellite sequences and mismatch repair gene expression (hMLH(1) and hMSH(2)) in RER(+) cells.
Main Methods:
- Utilized a RER(+) colon cancer cell line with a modified LacZ reporter gene containing a (CA)(14) repeat.
- Assessed microsatellite mutation frequency by measuring beta-galactosidase expression post-treatment with ATRA or PP.
- Examined mRNA levels of hMLH(1) and hMSH(2) using reverse transcription-polymerase chain reaction (RT-PCR).
Main Results:
- ATRA and PP did not inhibit cell proliferation at tested concentrations.
- Treatment with ATRA or PP significantly reduced microsatellite mutations in RKO transfectant clones.
- No detectable expression of hMLH(1) and hMSH(2) was observed following ATRA or PP treatment.
Conclusions:
- ATRA and PP demonstrate inhibitory effects on microsatellite instability in cancer cells.
- These findings suggest a beneficial role for ATRA and PP in stabilizing genomic DNA.
- The mechanism does not appear to involve the direct upregulation of hMLH(1) and hMSH(2) expression in this context.
