Detection of Cu(I) and Zn(II) ions in colon tissues by multi-photon microscopy: novel marker of antioxidant status of colon neoplasm

AIMS Establishing probe-based analysis is important for developing multi-photon microscopy (MPM) to make an early diagnosis of colon neoplasm and assess its antioxidant status. Cu(I) and Zn(II) ions are trace elements which roll as cofactors of antioxidant, superoxide dismutase. However, there have been no reports on the features of MPM image using probe of Cu(I) and Zn(II) ions. Our main objective in this study was application of newly developed multi-photon probe (MP) probe on Cu(I) and Zn(II) ions as a tool to assess antioxidative status of colon neoplasm. METHODS This study was a pilot study. Colon cancer cell lines (ACT116 and HT-29), NIH3T3 cells and tissues of normal colon mucosa and colon neoplasm obtained during colonoscopic biopsy from 17 patients were stained with MP probes for Cu(I) and Zn(II) (ACu1 and AZn1). Cu(I)/Zn(II) levels in the cells and tissues were determined by detecting MP-excited fluorescence by MPM. RESULTS MPM images of cells stained with MP probes revealed that Cu(I) was more abundant in ACT116 and HT-29 cells than in NIH3T3 cells, while Zn(II) was more abundant in NIH3T3 cells than in ACT116 and HT-29 cells. Normal tissues had a defined texture, whereas adenoma/adenocarcinoma tissues were amorphous. The level of Cu(I) increased and that of Zn(II) decreased with the transition from normal to adenoma to adenocarcinoma tissue. CONCLUSION MPM can be used to determine the relative Cu(I)/Zn(II) levels in cells and colon tissues by using ACu1 and AZn1 as MPM probes. These finding are new research tools for gastroenterologists to assess antioxidant status of colon neoplasm.