Radiosensitivity of colorectal cancer cells and its relationship to related genes

2002 Fiscal Year Final Research Report Summary

• Project/Area Number: 13671285
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Digestive surgery
• Research Institution: The University of Tokyo
• Principal Investigator: HORI Nobukazu The University of Tokyo, Faculty of Medicine, Research Associate, 医学部附属病院, 助手 (90282631)
• Co-Investigator(Kenkyū-buntansha): NAGAWA Hirokazu The University of Tokyo, Faculty of Medicine, Professor, 医学部附属病院, 教授 (80228064) ; WATAMABE Toshiaki The University of Tokyo, Faculty of Medicine, Associate Professor, 医学部附属病院, 助教授 (80210920)
• Project Period (FY): 2001 – 2002
• Keywords: colorectal cancer / primary culture / radiosensitivity

Research Abstract

The kinetics of radiation-induced cell killing were studied in cancer cell lines which express wild-type p53 and mutated p53. Cell survival was measured by standard colony-formation assay and cell lines which express wild-type p53 show greater radiosensitisvity than cell lines which express mutated p53. One of the p53 wild-type cell lines, LS174, shows prolonged radiation-induced G2 block which may be related to the down-reulation of P34^<edc2> after irradiation.
We then primarily cultured the colorectal cancer cells from the cancer specimens, and studied the expression of p53 and P21 before and after irradiation to find out the mutation status of p53 gene. We confirmed the mutation by PCR-SSCP and direct sequence. We identified the tumorigenecity of obtained cells with soft agar culture and found out cancer cell colonies which showed clifferenrt genetic characteristics from the same samples. This fact showed the heterogeneity of cancer and might be explained by the multistep carcinogenesis of colorectal cancer. We checked the truncation of APO protein and found out the mutation of most of the cultured cells, which showed the possibility that mutation of apc gene is one of the early events in carcinogenesis of colorectal cancer.
Lastly, we investigate the method to primarily culture cancer cells from very small amount of sample. We directly minced the small sample, plated on to the collgen-coated multiwells and picked up the colonies with assistance of phase-contrast microscope(Nikon). Cancer cells can be identified by the morphology of nucleus and nucleolus and nucleo-cytoplasmic ratio.