BIOLOGY DIVISION

4.BIOLOGY DIVISION

　The Biology Division is performing genetic and functional analyses of genes whose structure and/or expression are altered in cancer cells to understand the molecular basis of human carcinogenesis. The associations of genetic polymorphisms and germline mutations with cancer susceptibility are also being investigated. Those genes include tumor suppressor genes, oncogenes, and DNA repair genes. Application of the knowledge obtained from these studies in the cancer clinic has been further investigated to develop novel ways of molecular diagnosis, therapy, and prevention.
Genetic Alterations in Human Cancers

　Several chromosomal regions have been identified as being deleted or translocated in human cancers, and target genes in those regions have been cloned or identified.^(70-⁷³⁾ For example, the PPP1R3 gene on chromosome 7q is mutated in a wide range of human cancers.⁽⁷¹⁾ Extensive mutational analyses of the p53, p51, and ATM genes have been performed, however, p51 and ATM were not mutated in human cancer cells.^(74-⁷⁶⁾ The spectra of p53 gene mutations were different between lung adenocarcinoma and squamous cell carcinoma.⁽⁷⁴⁾ Several genes putatively involved in human carcinogenesis were cloned,^(77-⁷⁹⁾ and microsatellite instability was found in lymphoid but not in myeloid leukemia cell lines.⁽⁸⁰⁾
Functional Analysis of Cancer-related Genes

　There are several projects underway to study the functional consequence of genetic alterations in cancer cells. The mechanisms of phosphorylation of the p53 and RB proteins were investigated by preparing antibodies specific for each site of phosphorylation on these proteins.^(81-⁹⁴⁾ It was shown that phosphorylation of Ser20, in addition to Ser15, was important for activation of p53.⁽⁸⁷⁾ While it was previously shown that ATM phosphorylates Ser15 after DNA damage by gamma rays, ATR was found to phosphorylate the same site when cells were UV- irradiated. ⁽⁸⁸⁾ In contrast, DNA- PK, another member of ATM- family, was not involved in the phosphorylation of Ser15 in vivo. ^(82,⁹⁰⁾ A novel Cdk4- binding protein, p34SEI- 1, was discovered.⁽⁹⁵⁾ This protein activates Cdk4- cyclin D1 by inhibiting binding of p16 to Cdk4.
　The EVI- 1 gene was shown to be activated during and is sufficient for neuroectodermal P19 cell differentiation,⁽⁹⁶⁾ while the wild- type p16 gene activates the RB protein and suppresses the growth of small cell lung carcinoma cells with p16 inactivation.⁽⁹⁵⁾
Genetic Markers for Prognosis of Patients with Lung Cancer

　The prognostic significance of tumor suppressor gene inactivation was investigated in early stage lung carcinoma, and allelic imbalance on chromosome 9p as well as p53 mutations were shown to be associated with poor prognosis of stage I patients with non- small cell lung cancer.^(97,⁹⁸⁾
Genetic Polymorphisms and Cancer Susceptibility

　To develop novel methods to evaluate the cancer risk in each individual, genetic polymorphisms in genes for DNA repair and carcinogen metabolizing enzymes were determined in association with their enzymatic activities.^(99-¹⁰²⁾ It was shown that differences in the activities of the OGG1 and CYP2A6 genes were associated with susceptibility to lung cancers in patients with a smoking history.^(100,¹⁰¹⁾
Genetic Factors for Familial Aggregation of Gastric Cancer

　Familial gastric cancers were clinicopathologically characterized, and their genetic backgrounds were investigated.^(103,¹⁰⁴⁾ Criteria and guidelines for management of familial gastric cancer were defined by an international collaboration.⁽¹⁰⁴⁾ Familial aggregation of gastric cancer was detected in about 1% (31 of 3632)of gastric cancer patients. None of 31 familial cases fitted the clinical criteria of hereditary non- polyposis colorectal cancer or Li- Fraumeni syndrome in 31 familial cases. Microsatellite instability was detected in 3 of 13 familial cases, but no germline p53 mutations were detected. A germline E- cadherin mutation was detected in one of 3 diffuse types. These results indicated that germline mutations of the DNA mismatch repair, p53 and E- cadherin genes do not significantly contribute to such clustering.⁽¹⁰³⁾
Gene Therapy for Pleural Metastasis of Lung Cancer

　To assess the possibility of suicidal gene therapy for the treatment of pleural metastasis in lung cancer patients, liposome- mediated transfer of the herpes simplex virus thymidine kinase gene was performed using a mouse model of pleural metastasis for lung cancer,⁽¹⁰⁵⁾ which was previously developed in the Division. The survival rates of the ganciclovir- treated group were significantly better than those of the control groups, suggesting the therapeutic feasibility of an in vivo lipofection- based suicidal gene/prodrug strategy for pleural metastasis of lung cancer.




4.BIOLOGY DIVISION



	The Biology Division is performing genetic and functional analyses of genes whose structure and/or expression are altered in cancer cells to understand the molecular basis of human carcinogenesis. The associations of genetic polymorphisms and germline mutations with cancer susceptibility are also being investigated. Those genes include tumor suppressor genes, oncogenes, and DNA repair genes. Application of the knowledge obtained from these studies in the cancer clinic has been further investigated to develop novel ways of molecular diagnosis, therapy, and prevention. Genetic Alterations in Human Cancers 　Several chromosomal regions have been identified as being deleted or translocated in human cancers, and target genes in those regions have been cloned or identified.^(70-⁷³⁾ For example, the PPP1R3 gene on chromosome 7q is mutated in a wide range of human cancers.⁽⁷¹⁾ Extensive mutational analyses of the p53, p51, and ATM genes have been performed, however, p51 and ATM were not mutated in human cancer cells.^(74-⁷⁶⁾ The spectra of p53 gene mutations were different between lung adenocarcinoma and squamous cell carcinoma.⁽⁷⁴⁾ Several genes putatively involved in human carcinogenesis were cloned,^(77-⁷⁹⁾ and microsatellite instability was found in lymphoid but not in myeloid leukemia cell lines.⁽⁸⁰⁾ Functional Analysis of Cancer-related Genes 　There are several projects underway to study the functional consequence of genetic alterations in cancer cells. The mechanisms of phosphorylation of the p53 and RB proteins were investigated by preparing antibodies specific for each site of phosphorylation on these proteins.^(81-⁹⁴⁾ It was shown that phosphorylation of Ser20, in addition to Ser15, was important for activation of p53.⁽⁸⁷⁾ While it was previously shown that ATM phosphorylates Ser15 after DNA damage by gamma rays, ATR was found to phosphorylate the same site when cells were UV- irradiated. ⁽⁸⁸⁾ In contrast, DNA- PK, another member of ATM- family, was not involved in the phosphorylation of Ser15 in vivo. ^(82,⁹⁰⁾ A novel Cdk4- binding protein, p34SEI- 1, was discovered.⁽⁹⁵⁾ This protein activates Cdk4- cyclin D1 by inhibiting binding of p16 to Cdk4. 　The EVI- 1 gene was shown to be activated during and is sufficient for neuroectodermal P19 cell differentiation,⁽⁹⁶⁾ while the wild- type p16 gene activates the RB protein and suppresses the growth of small cell lung carcinoma cells with p16 inactivation.⁽⁹⁵⁾ Genetic Markers for Prognosis of Patients with Lung Cancer 　The prognostic significance of tumor suppressor gene inactivation was investigated in early stage lung carcinoma, and allelic imbalance on chromosome 9p as well as p53 mutations were shown to be associated with poor prognosis of stage I patients with non- small cell lung cancer.^(97,⁹⁸⁾ Genetic Polymorphisms and Cancer Susceptibility 　To develop novel methods to evaluate the cancer risk in each individual, genetic polymorphisms in genes for DNA repair and carcinogen metabolizing enzymes were determined in association with their enzymatic activities.^(99-¹⁰²⁾ It was shown that differences in the activities of the OGG1 and CYP2A6 genes were associated with susceptibility to lung cancers in patients with a smoking history.^(100,¹⁰¹⁾ Genetic Factors for Familial Aggregation of Gastric Cancer 　Familial gastric cancers were clinicopathologically characterized, and their genetic backgrounds were investigated.^(103,¹⁰⁴⁾ Criteria and guidelines for management of familial gastric cancer were defined by an international collaboration.⁽¹⁰⁴⁾ Familial aggregation of gastric cancer was detected in about 1% (31 of 3632)of gastric cancer patients. None of 31 familial cases fitted the clinical criteria of hereditary non- polyposis colorectal cancer or Li- Fraumeni syndrome in 31 familial cases. Microsatellite instability was detected in 3 of 13 familial cases, but no germline p53 mutations were detected. A germline E- cadherin mutation was detected in one of 3 diffuse types. These results indicated that germline mutations of the DNA mismatch repair, p53 and E- cadherin genes do not significantly contribute to such clustering.⁽¹⁰³⁾ Gene Therapy for Pleural Metastasis of Lung Cancer 　To assess the possibility of suicidal gene therapy for the treatment of pleural metastasis in lung cancer patients, liposome- mediated transfer of the herpes simplex virus thymidine kinase gene was performed using a mouse model of pleural metastasis for lung cancer,⁽¹⁰⁵⁾ which was previously developed in the Division. The survival rates of the ganciclovir- treated group were significantly better than those of the control groups, suggesting the therapeutic feasibility of an in vivo lipofection- based suicidal gene/prodrug strategy for pleural metastasis of lung cancer.