Ethanol-induced DNA damage and the expression of repair-related molecules in human gastric carcinoma AGS cells with use of an acid pump antagonist and proton pump inhibitor

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Background: Proton pump inhibitor (PPI) inhibits gastric acid secretion by strongly suppressing H + / K +- ATPase of parietal cells and is a major drug for peptic ulcers and gastroesophageal reflux. Recently it was reported that PPI has antioxidant and anti- inflammatory effects as well as a powerful acid inhibitory effect. To analyze the DNA repair capacity from the antioxidant effect of acid pump antagonist (Revanex-RN) and proton pump inhibitor (Omeprazole-OP), this study examined ethanol-induced DNA damage and the expression of repair related molecules in human gastric cancer AGS cells pretreated with an acid pump antagonist and a proton pump inhibitor.

Methods: AGS, a human gastric cancer cell line was obtained from ATCC, was treated with ethanol (0, 2, 4, 6, 8, 10%) during 1hr. MTT and Comet assay were performed to evaluate ethanol-induced DNA damage. The optimum concentration of ethanol which caused DNA damage was established. And AGS cells were cultured in proper concentration of RN or OP overnight. Then, these cells were treated with 5% ethanol during 1hr. DNA damage and recovery were represented the value of Olive tail moment in comet assay. Western blot was also performed to detect expression of DNA polymerase beta, APE/ref-1, PCNA, and GADD45.

Results: The DNA damage of AGS cell depended upon ethanol concentration distinctly. Damaged cells showed up recovered tendency in the group treated with low dose RN or OP. In addition, DNA repair enzymes including DNA polymerase beta and APE/ref-1 which were associated with mechanism of base excision repair (BER) were increased. A relevant protein such as GADD45 was also increased significantly.

Conclusions: PPI has capacity to recover damaged DNA, which is associated with increased expression of GADD45 directly. Therefore, PPI offers cancer prevention by reducing the level of DNA damage in the gastric mucosa. GADD45 is also likely to suggest that it could be used a major factor on the injury mechanism and an indicator of mucosal damage in stomach. Moreover, RN, an acid pump antagonist is expected to have the higher safety compared to the existing PPIs and considered to be equal to PPIs in terms of anti-cancer effect.

No significant financial relationships to disclose.

Novel multiphoton microscopy probe and feasibility study for colon cancer: Probe on trace elements–related antioxidant

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Background: Multiphoton microscopy (MPM) has gained increasing popularity during the past few years because of the distinct advantages over single-photon microscopy, which includes increased penetration depth and low out-of-focus photodamage. However, there had been no report on multiphoton probes for malignancy. Previous studies reported that Zn and Cu ions which are co-factor of antioxidants such as superoxide dismutase (SOD), altered in malignancy tissue. The aim of this study was to evaluate application of the multiphoton (MP) probe of Zn and Cu for colon cancer tissues.

Methods: We monitored the Zn/Cu ions in the colon cancer cell lines with multiphoton probe Microscopy. The multiphoton probe AZn2+ (C38H38N6O3) and ACu+ (C34H47N3O3S4), we developed and obtained the patent on it, were stained in live cancer cell lines. The tissues of colon cancer, adenoma and normal mucosa were obtained by biopsy during colonoscopy. Then the tissues were stained with 20μM of the MP probes for Zn/Cu ions. The distribution and concentration of zinc and copper ions were monitored by MPM by following the change in MPEF along the depth of tissue.

Results: The majority of Zn2+ and Cu+ ions distributed in cytosole. The average multi-photon excited fluorescence (MPEF) intensities due to Cu, Zn, and Cu/Zn ratio were remarkably different between the normal mucosa and adenoma/adenocarcinoma tissues. The Zn2+ content was significantly lower and the Cu2+ content was significantly higher to result in a much lower the Zn/Cu ratio in adenoma/adenocarcinoma than in normal mucosa tissues.

Conclusions: We have obtained multiphoton microscopy images of normal and cancer cell lines as well as mucosa and adenoma/adenocarcinoma tissues labeled with newly developed MP probes AZn1 and ACu1.

No significant financial relationships to disclose.