PHARMACOLOGY DIVISION

5.PHARMACOLOGY DIVISION

　The research program in the Pharmacology Division focuses on the discovery of new approaches for cancer treatments that can be translated to clinical application. The basis of this work is fundamental research into the anti- tumor mechanisms of the immunocompetent cells and drugs, and determination of the cellular and molecular determinants of tumor cell recognition, drug sensitivity and drug resistance. The more translational research projects include the development of the most appropriate schedules for different types of effector cells and drugs for cancer treatment.
Anti-tumor Immunity of NK-like T Cells

　The murine NK- like tMK- 2 T cell line was established by subcutaneous xenografting of surgical specimens from an inflammatory breast cancer patient. These cells are also excellent effector cells in vivo against the autochthonously methylcholanthrene- induced tumors either for prevention of tumors or for therapeutic treatment of progressed tumors.⁽¹⁰⁶⁾ Immunization of these tMK- 2U cells enabled us to establish a U5A2- 13 monoclonal antibody (mAb), which recognizes NK- like T cells. The U5A2- 13- positive T cells produced abundant IL- 4 as well as extremely high levels of IFN g , while this was not observed with U5A2- 13- negative T cells. Based on the present results, the U5A2- 13 mAb appears to be a valuable tool for the study of NK- like T cells.⁽¹⁰⁷⁾
Elevated Serum Levels of Thioredoxin in Patients with Chronic and/or Malignant Liver Diseases

　The serum concentration of TRX in hepatocellular carcinoma (HCC) patients was much higher than that in both liver cirrhosis or chronic hepatitis without HCC and of normal volunteers. An immunohistochemical study of TRX expression in patients with HCC was performed. HCC specimens were strongly stained for TRX, whereas the normal liver of the same patient was only weakly stained.^(108,¹⁰⁹⁾
Biological and Biochemical Pharmacology

　Antitumor activities of novel agents were evaluated by in vitro and in vivo studies. Anti- ganglioside and anti- EGFR antibodies showed potent antitumor activities in vitro and in vivo.⁽¹¹⁰⁾ Target- based drugs do not always show tumor shrinkage. Therefore the appropriate biological markers are essential to evaluate the clinical effect of these drugs. The receptors for target- based drugs such as CPT- 11, UCN- 01, and E7070 were investigated. Cell cycle regulatory molecules including p16^INK4, p27^KIP1, IRF- 1, p53, and cyclins were found to be determinants of the activities of these drugs.^(111-¹¹³⁾ Autophosphorylation of EGFR is a possible biological marker for a tyrosine kinase inhibitor for EGFR (ZD- 1839). We examinated the potential combined effects of cytotoxic and non cytotoxic agents. In vitro and in vivo evaluation demonstrated that KRN5500, TAS103, and Herceptin exerted the supraadditive effects if combined with cytotoxic agents including platinums or CPT- 11.^(114,¹¹⁵⁾
Antimitotic Agents

　Antimitotic agents including paclitaxel and docetaxel are active against solid tumors. It is important to clarify the factors responsible for the antitumor effects of these agents to predict the clinical response. Taxanes act on the MAP kinase pathway and influence microtubule dynamics through the interaction of tubulin with microtubule- associated proteins.⁽¹¹⁶⁾ Inhibition of MAP kinase caused growth inhibition and induced apoptosis of tumor cells.⁽¹¹⁷⁾ The antimitotic agents possibly act on the microenvironment around the tumor tissues in vivo. Lewis lung carcinoma secreting IL- 6 or TNF- a showed higher sensitivity to antimitotic agents and increased permeability of tumor vessels.
Drug Resistance

　Drug- transport, intracellular de- toxification,⁽¹¹⁸⁾ and DNA repair ⁽¹¹⁹⁾ are the major determinants of the tumor sensitivity to DNA- damaging agents.⁽¹²⁰⁾ A human ATP- binding cassette transporter SMRP and its mouse homologue were isolated, and the SMRP transcript was found to be a splicing variant of the MRP5 gene. We designated the MRP5 mRNA as MRP5a and the previously identified SMRP mRNA as MRP5b. Both MRP5b and MRP5a were expressed in normal human tissues. Another splicing variant was expressed in pituitary gland. Investigations into the functional differences between these variants are on- going.




5.PHARMACOLOGY DIVISION



	The research program in the Pharmacology Division focuses on the discovery of new approaches for cancer treatments that can be translated to clinical application. The basis of this work is fundamental research into the anti- tumor mechanisms of the immunocompetent cells and drugs, and determination of the cellular and molecular determinants of tumor cell recognition, drug sensitivity and drug resistance. The more translational research projects include the development of the most appropriate schedules for different types of effector cells and drugs for cancer treatment. Anti-tumor Immunity of NK-like T Cells 　The murine NK- like tMK- 2 T cell line was established by subcutaneous xenografting of surgical specimens from an inflammatory breast cancer patient. These cells are also excellent effector cells in vivo against the autochthonously methylcholanthrene- induced tumors either for prevention of tumors or for therapeutic treatment of progressed tumors.⁽¹⁰⁶⁾ Immunization of these tMK- 2U cells enabled us to establish a U5A2- 13 monoclonal antibody (mAb), which recognizes NK- like T cells. The U5A2- 13- positive T cells produced abundant IL- 4 as well as extremely high levels of IFN g , while this was not observed with U5A2- 13- negative T cells. Based on the present results, the U5A2- 13 mAb appears to be a valuable tool for the study of NK- like T cells.⁽¹⁰⁷⁾ Elevated Serum Levels of Thioredoxin in Patients with Chronic and/or Malignant Liver Diseases 　The serum concentration of TRX in hepatocellular carcinoma (HCC) patients was much higher than that in both liver cirrhosis or chronic hepatitis without HCC and of normal volunteers. An immunohistochemical study of TRX expression in patients with HCC was performed. HCC specimens were strongly stained for TRX, whereas the normal liver of the same patient was only weakly stained.^(108,¹⁰⁹⁾ Biological and Biochemical Pharmacology 　Antitumor activities of novel agents were evaluated by in vitro and in vivo studies. Anti- ganglioside and anti- EGFR antibodies showed potent antitumor activities in vitro and in vivo.⁽¹¹⁰⁾ Target- based drugs do not always show tumor shrinkage. Therefore the appropriate biological markers are essential to evaluate the clinical effect of these drugs. The receptors for target- based drugs such as CPT- 11, UCN- 01, and E7070 were investigated. Cell cycle regulatory molecules including p16^INK4, p27^KIP1, IRF- 1, p53, and cyclins were found to be determinants of the activities of these drugs.^(111-¹¹³⁾ Autophosphorylation of EGFR is a possible biological marker for a tyrosine kinase inhibitor for EGFR (ZD- 1839). We examinated the potential combined effects of cytotoxic and non cytotoxic agents. In vitro and in vivo evaluation demonstrated that KRN5500, TAS103, and Herceptin exerted the supraadditive effects if combined with cytotoxic agents including platinums or CPT- 11.^(114,¹¹⁵⁾ Antimitotic Agents 　Antimitotic agents including paclitaxel and docetaxel are active against solid tumors. It is important to clarify the factors responsible for the antitumor effects of these agents to predict the clinical response. Taxanes act on the MAP kinase pathway and influence microtubule dynamics through the interaction of tubulin with microtubule- associated proteins.⁽¹¹⁶⁾ Inhibition of MAP kinase caused growth inhibition and induced apoptosis of tumor cells.⁽¹¹⁷⁾ The antimitotic agents possibly act on the microenvironment around the tumor tissues in vivo. Lewis lung carcinoma secreting IL- 6 or TNF- a showed higher sensitivity to antimitotic agents and increased permeability of tumor vessels. Drug Resistance 　Drug- transport, intracellular de- toxification,⁽¹¹⁸⁾ and DNA repair ⁽¹¹⁹⁾ are the major determinants of the tumor sensitivity to DNA- damaging agents.⁽¹²⁰⁾ A human ATP- binding cassette transporter SMRP and its mouse homologue were isolated, and the SMRP transcript was found to be a splicing variant of the MRP5 gene. We designated the MRP5 mRNA as MRP5a and the previously identified SMRP mRNA as MRP5b. Both MRP5b and MRP5a were expressed in normal human tissues. Another splicing variant was expressed in pituitary gland. Investigations into the functional differences between these variants are on- going.