PubMed · 5564173
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A Dupont. 1971. [Rectocolic polyps and polyposis. Anatomopathologic study].. https://pubmed.ncbi.nlm.nih.gov/5564173/
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We have found a significant concordance between the in vitro replication errors of human DNA polymerase beta and in vivo point mutations of the adenomatous polyposis coli (APC) gene that leads to colon cancer. We determined the error spectrum of DNA polymerase beta in the human APC gene under PCR conditions and compared it with the set of mutations reported in human colon tumors. Polymerase beta created seven hotspot mutations within 141 target bp analyzed in APC exon 15. Three of these polymerase beta hotspots, 2 frameshifts and a bp substitution mutation, were concordant with 3 of 13 APC hotspots detected in human colon cancers in the same DNA sequences. These 3 concordant hotspots accounted for some 54% of reported in vivo APC hotspot mutations. Using the assumption of a hypergeometric distribution of hotspot mutations among bp of the scanned sequences, the probability of this concordance occurring by chance is <4 x 10(-4). These data support the hypothesis that DNA polymerase beta errors are an important fraction of cancer-causing APC mutations.
OBJECTIVE: To clarify the possible effect of reactive oxygen species such as hydrogen peroxide on progression of human colorectal cancer. METHOD: Human colon carcinoma cell lines, L174T and HCT8, were treated with low concentration of hydrogen peroxide (10(-5) mol/L, 10(-7) mol/L and 10(-9) mol/L, possessed no effect on cancer cell growth) for 24 hours before being co-cultured with human endothelial cell line ECV-304. The migration of ECV-304 induced by cancer cells was calculated and the expression of vascular endothelial growth factor (VEGF) in cancer cells was determined using RT-PCR and ELISA. Dactinomycin (1.5 microg/ml) was applied to block the transcription of cancer cell so as to observe the effect site of cell. Finally the activity of NF-KappaB of cancer cells was estimated using laser scanning cytometry. RESULTS: Exogenous hydrogen peroxide of low concentration promoted the migration of endothelial cell induced by colon cancer cell. When the concentration of H(2)O(2) was 10(-5) mol/L, the average number of migration of endothelial cell induced by LS174T was 202.6 +/- 70.2, higher than the value of 154.6 +/- 37.9 when no H(2)O(2) was given (t = 3.4751, P = 0.0083). When the concentration of H(2)O(2) was 10(-5) mol/L, the average number of migration of endothelial cell induced by HCT8 was 145.4 +/- 65.3, higher than the value of 113 +/- 72.7 when no H(2)O(2) was given (t = 4.4183, P = 0.0084). The expression of vascular endothelial growth factor in cancer cells was enhanced to a certain degree, which could be blocked by Dactinomycin. And the half-time of VEGF mRNA was not prolonged by treatment with hydrogen peroxide. The activity of NF-KappaB of both colon carcinoma cell lines was at a higher level after being treated with hydrogen peroxide for 24 hours. CONCLUSION: Hydrogen peroxide increases vascular endothelial growth factor expression in colon cancer cell, and it is possible that such reactive oxygen species as hydrogen peroxide facilitates development of colon cancer.
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