Investigative Treatment Division

19. Investigative Treatment Division

　The main goal of the research in this division is the development of new strategies of cancer prevention, diagnosis and treatment based on the better understanding of biology of cancer tissues and interactions between tumor and host.
Analysis of Precancerous Lesions

　We have continued some research on histogenesis of cancer and biology of precancerous lesion.^(239-243) We found that isolated single gastric glands from intestinal metaplasia showed polyclonality in terms of X chromosome inactivation.⁽²⁴⁰⁾ This finding was unexpected from the classical view of histogenesis of gastric gland. A study using transgenic mouse having b-galactosidase gene on an X chromosome revealed that a proportion of gastric glands retain their polyclonality during animal development suggesting the existence of stem gland.⁽²⁴³⁾
Analysis of Lung Cancer Patients with Extreme Clinicopathological Features

　We have chosen a fraction of lung cancer patients having extreme clinicopathological features to analyze the genetic factors of lung cancer.⁽²⁴⁴⁾ This year, lung cancer patients with familial clustering of cancer were analyzed for replication errors. RER was higher in the lung cancer tissue from patients with a family history than in those without a family history.⁽²⁴⁵⁾ Some lung adenocarcinoma patients were found to be associated with extremely large numbers of atypical adenomatous hyperplasia (AAH). Since the histology of TSC-associated rare lung lesions and AAH is almost indistinguishable, and because one of our lung adenocarcinoma patients had more than one hundred AAH in the resected lobe, tuberous sclerosis gene-associated regions were analyzed for a possible tumor suppresser gene by LOH analysis. Results clearly showed that in some fraction of patients with lung adenocarcinoma, especially those associated with large number of AAH, genetic factors closely linked to TSC genes play a role in carcinogenesis.⁽²⁴⁶⁾
A New Method for Treating Small Lung Cancer

　Since the introduction of helical CT into screening of lung cancer, lesions less than 0.5 cm in diameter have been diagnosed as lung tumor. It is extremely important to characterize these tumors both clinically and pathologically. It is also very important to develop a new method of treatment for these lesions. The possibility of injecting ethanol or paclitaxel directly from outside under CT guidance was examined.⁽²⁴⁷⁾ Results showed that ethanol or paclitaxel injection into the lung is not as harmful and the effect was confined to the portion of injection, indicating the potential application of this approach.
Implication of Nitric Oxide in Carcinogenesis and Clinical Course of Cancer

　The molecular mechanisms of gene regulation of nitric oxide synthases and biochemical consequences of nitric oxide production have been studied.^(248-252) Both NO and prostaglandin are produced by the processes of inflammation. Prostaglandin J2, an oxidative product of D2, was found to suppress iNOS induction in macrophages stimulated by LPS.⁽²⁵¹⁾ This finding was further analyzed and the ligand of the nuclear receptor PPARg was found to inhibit the induction. In connection to the hypoxic reaction which is critical for tumor progression, we have analyzed the effect of nitric oxide on hypoxia response gene expression. When several tumor cell lines were treated with nitric oxide-generating compounds, VEGF gene expression was remarkably stimulated. Together with VEGF, expression of some hypoxia response genes was also stimulated. These findings suggest that nitric oxide produced by either tumor cells or surrounding tissue could be a determining factor of tumor vascular formation. When several tumor cell lines were treated with nitric oxide, they were found to become more resistant to apoptosis induced by vincristine, vinblastine and paclitaxel.⁽²⁴⁹⁾ The mechanisms of apoptosis resistance were found to be at least in part due to inhibition of caspase 3, and caspase 9 activation (unpublished data). It was shown that nitric oxide is produced when cells and tissues are exposed to hypoxia,⁽²⁴⁸⁾ DNA damaging agents and nutrient deficiency. These results suggest that nitric oxide may act as an SOS-signaling mediator.
Construction of a New Strategy of Gene Therapy

　A completely new gene therapy expression vector was constructed based on the human U1 snRNA transcription cassette.⁽²⁵³⁾ U1 snRNA forms a complex with pre-mRNA between the 5'terminus and the splice donor sites and regulates mRNA splicing, and is characterized by its extremely long half life. When mutations were introduced into the 5'end of U1 snRNA, changes in the splicing pattern were noticed using rat serum albumin gene as a model. This vector could be applicable to a wide variety of gene systems.




	19. Investigative Treatment Division



		The main goal of the research in this division is the development of new strategies of cancer prevention, diagnosis and treatment based on the better understanding of biology of cancer tissues and interactions between tumor and host. Analysis of Precancerous Lesions 　We have continued some research on histogenesis of cancer and biology of precancerous lesion.^(239-243) We found that isolated single gastric glands from intestinal metaplasia showed polyclonality in terms of X chromosome inactivation.⁽²⁴⁰⁾ This finding was unexpected from the classical view of histogenesis of gastric gland. A study using transgenic mouse having b-galactosidase gene on an X chromosome revealed that a proportion of gastric glands retain their polyclonality during animal development suggesting the existence of stem gland.⁽²⁴³⁾ Analysis of Lung Cancer Patients with Extreme Clinicopathological Features 　We have chosen a fraction of lung cancer patients having extreme clinicopathological features to analyze the genetic factors of lung cancer.⁽²⁴⁴⁾ This year, lung cancer patients with familial clustering of cancer were analyzed for replication errors. RER was higher in the lung cancer tissue from patients with a family history than in those without a family history.⁽²⁴⁵⁾ Some lung adenocarcinoma patients were found to be associated with extremely large numbers of atypical adenomatous hyperplasia (AAH). Since the histology of TSC-associated rare lung lesions and AAH is almost indistinguishable, and because one of our lung adenocarcinoma patients had more than one hundred AAH in the resected lobe, tuberous sclerosis gene-associated regions were analyzed for a possible tumor suppresser gene by LOH analysis. Results clearly showed that in some fraction of patients with lung adenocarcinoma, especially those associated with large number of AAH, genetic factors closely linked to TSC genes play a role in carcinogenesis.⁽²⁴⁶⁾ A New Method for Treating Small Lung Cancer 　Since the introduction of helical CT into screening of lung cancer, lesions less than 0.5 cm in diameter have been diagnosed as lung tumor. It is extremely important to characterize these tumors both clinically and pathologically. It is also very important to develop a new method of treatment for these lesions. The possibility of injecting ethanol or paclitaxel directly from outside under CT guidance was examined.⁽²⁴⁷⁾ Results showed that ethanol or paclitaxel injection into the lung is not as harmful and the effect was confined to the portion of injection, indicating the potential application of this approach. Implication of Nitric Oxide in Carcinogenesis and Clinical Course of Cancer 　The molecular mechanisms of gene regulation of nitric oxide synthases and biochemical consequences of nitric oxide production have been studied.^(248-252) Both NO and prostaglandin are produced by the processes of inflammation. Prostaglandin J2, an oxidative product of D2, was found to suppress iNOS induction in macrophages stimulated by LPS.⁽²⁵¹⁾ This finding was further analyzed and the ligand of the nuclear receptor PPARg was found to inhibit the induction. In connection to the hypoxic reaction which is critical for tumor progression, we have analyzed the effect of nitric oxide on hypoxia response gene expression. When several tumor cell lines were treated with nitric oxide-generating compounds, VEGF gene expression was remarkably stimulated. Together with VEGF, expression of some hypoxia response genes was also stimulated. These findings suggest that nitric oxide produced by either tumor cells or surrounding tissue could be a determining factor of tumor vascular formation. When several tumor cell lines were treated with nitric oxide, they were found to become more resistant to apoptosis induced by vincristine, vinblastine and paclitaxel.⁽²⁴⁹⁾ The mechanisms of apoptosis resistance were found to be at least in part due to inhibition of caspase 3, and caspase 9 activation (unpublished data). It was shown that nitric oxide is produced when cells and tissues are exposed to hypoxia,⁽²⁴⁸⁾ DNA damaging agents and nutrient deficiency. These results suggest that nitric oxide may act as an SOS-signaling mediator. Construction of a New Strategy of Gene Therapy 　A completely new gene therapy expression vector was constructed based on the human U1 snRNA transcription cassette.⁽²⁵³⁾ U1 snRNA forms a complex with pre-mRNA between the 5'terminus and the splice donor sites and regulates mRNA splicing, and is characterized by its extremely long half life. When mutations were introduced into the 5'end of U1 snRNA, changes in the splicing pattern were noticed using rat serum albumin gene as a model. This vector could be applicable to a wide variety of gene systems.