Pharmacology Division

5. Pharmacology Division

The Pharmacology Division is conducting translational studies to discover new approaches for the treatment of cancer. Basic and applied pharmacological research are crucial for the development and rational use of anti-cancer drugs. The major scientific goals of the Pharmacology Division involve fundamental analysis of the mechanisms of action of anticancer drugs and clarification of the molecular determinants of drug sensitivity and resistance. The development of the most appropriate schedules is also essential for the further improvement of treatment outcome. The practical strategies include: (1) basic studies for the clinical application of combination chemotherapy, chemo-gene therapy, and chemotherapy combined with biological response modifier; (2) pharmacokinetic and pharmacodynamic analyses; (3) phase I, II, and III studies of new anticancer agents and combined modalities.
Biological and Biochemical Pharmacology

Our primary research interest has been the clarification of the molecular mechanisms of anticancer drugs which include inhibitors of DNA topoisomerases, DNA damage and repair, cell cycle regulation,⁽⁸¹⁾ and microtubule dynamics.⁽⁸²⁾ KW-2189 exerts antitumor activity by inducing DNA strand breaks and the inhibition DNA repair through a caffeine-sensitive pathway.⁽⁸³⁾ Overexpression of p16^INK4 caused increased sensitivity of lung cancer cells to topoisomerase I inhibitors such as CPT-11 through up-regulation of topoisomerase I mRNA.⁽⁸⁴⁾
Drug Resistance

Acquisition of drug resistance by tumor cells is frequently observed in cancer patients receiving chemotherapeutic treatment. One of the major mechanisms of cisplatin resistance is considered to be decreased intracellular accumulation of drugs caused by decreased influx and/or increased efflux of the drug. Another mechanism is the increased detoxification mediated by glutathion (GSH). A drug, KW-2149, was found to be active in cells that were drug-resistant due to an increase in intracellucar GSH content.⁽⁸⁵⁾ An elevation of glutathione levels and increase in cisplatin resistance have been achieved by transfection of g- glutamylcysteine synthetase heavy subunit (g-GCS) cDNA.⁽⁸⁶⁾ The expression of the g-GCS gene was transcriptionally up-regulated by cisplatin.⁽⁸⁷⁾ The contribution of the 5-flanking sequence of the g-GCS gene to cisplatin-induced transcriptional up-regulation was studied using growth hormone reporter deletion constructs. The proximal sequence from -192 to +91 bp of the g-GCS gene was found to be involved in cisplatin induced up-regulation in SBC-3 cells.^{(87, 88)} Overexpression of the g-GCS gene leads to increased drug transport activity across the cell membrane which is mediated by an ATP-dependent transporter.⁽⁸⁶⁾
The cDNA of an ATP-dependent transporter was cloned from a cisplatin-resistant human lung cancer cell line and designated as the short type of the multidrug resistance protein homologue, SMRP.⁽⁸⁹⁾ SMRP, which belongs to the ATP binding cassette (ABC) superfamily, was composed of 946 amino acids and had two ABCs with walker A and B motifs. This gene was mapped to chromosome 3 at band q27 by fluorescence in situ hybridization (FISH) analysis and was found to be expressed in various tissues by Northern blot analysis.
Development of Innovative Therapy

A three-dimensional method was developed to analyze the combination effect of anticancer drugs.^(90-92) The combination of cisplatin and gemcitabine showed a synergistic effect. Preclinical evaluation of chemotherapy combined with radiotherapy, surgery (adjuvant therapy), and immunotherapy^(93-95) were performed.^{(96, 97)} Nabelbine, an antimitotic agent, and topotecan, a topoisomerase I inhibitor, exert radiosensitizing effects. A combination phase I study of paclitaxel and cisplatin was conducted in patients with previously untreated, unresectable stage III or IV non-small cell lung cancer. Twenty five assessable patients were entered. The most frequent adverse effects were leukopenia, neutropenia, and bilirubinemia. A pharmacokinetic study revealed no drug-drug interactions. The recommended doses were 180 mg/m² of paclitaxel in combined with 60 or 80 mg/m² of cisplatin. Other related clinical studies are listed.^(98-102)




	5. Pharmacology Division



		The Pharmacology Division is conducting translational studies to discover new approaches for the treatment of cancer. Basic and applied pharmacological research are crucial for the development and rational use of anti-cancer drugs. The major scientific goals of the Pharmacology Division involve fundamental analysis of the mechanisms of action of anticancer drugs and clarification of the molecular determinants of drug sensitivity and resistance. The development of the most appropriate schedules is also essential for the further improvement of treatment outcome. The practical strategies include: (1) basic studies for the clinical application of combination chemotherapy, chemo-gene therapy, and chemotherapy combined with biological response modifier; (2) pharmacokinetic and pharmacodynamic analyses; (3) phase I, II, and III studies of new anticancer agents and combined modalities. Biological and Biochemical Pharmacology Our primary research interest has been the clarification of the molecular mechanisms of anticancer drugs which include inhibitors of DNA topoisomerases, DNA damage and repair, cell cycle regulation,⁽⁸¹⁾ and microtubule dynamics.⁽⁸²⁾ KW-2189 exerts antitumor activity by inducing DNA strand breaks and the inhibition DNA repair through a caffeine-sensitive pathway.⁽⁸³⁾ Overexpression of p16^INK4 caused increased sensitivity of lung cancer cells to topoisomerase I inhibitors such as CPT-11 through up-regulation of topoisomerase I mRNA.⁽⁸⁴⁾ Drug Resistance Acquisition of drug resistance by tumor cells is frequently observed in cancer patients receiving chemotherapeutic treatment. One of the major mechanisms of cisplatin resistance is considered to be decreased intracellular accumulation of drugs caused by decreased influx and/or increased efflux of the drug. Another mechanism is the increased detoxification mediated by glutathion (GSH). A drug, KW-2149, was found to be active in cells that were drug-resistant due to an increase in intracellucar GSH content.⁽⁸⁵⁾ An elevation of glutathione levels and increase in cisplatin resistance have been achieved by transfection of g- glutamylcysteine synthetase heavy subunit (g-GCS) cDNA.⁽⁸⁶⁾ The expression of the g-GCS gene was transcriptionally up-regulated by cisplatin.⁽⁸⁷⁾ The contribution of the 5-flanking sequence of the g-GCS gene to cisplatin-induced transcriptional up-regulation was studied using growth hormone reporter deletion constructs. The proximal sequence from -192 to +91 bp of the g-GCS gene was found to be involved in cisplatin induced up-regulation in SBC-3 cells.^{(87, 88)} Overexpression of the g-GCS gene leads to increased drug transport activity across the cell membrane which is mediated by an ATP-dependent transporter.⁽⁸⁶⁾ The cDNA of an ATP-dependent transporter was cloned from a cisplatin-resistant human lung cancer cell line and designated as the short type of the multidrug resistance protein homologue, SMRP.⁽⁸⁹⁾ SMRP, which belongs to the ATP binding cassette (ABC) superfamily, was composed of 946 amino acids and had two ABCs with walker A and B motifs. This gene was mapped to chromosome 3 at band q27 by fluorescence in situ hybridization (FISH) analysis and was found to be expressed in various tissues by Northern blot analysis. Development of Innovative Therapy A three-dimensional method was developed to analyze the combination effect of anticancer drugs.^(90-92) The combination of cisplatin and gemcitabine showed a synergistic effect. Preclinical evaluation of chemotherapy combined with radiotherapy, surgery (adjuvant therapy), and immunotherapy^(93-95) were performed.^{(96, 97)} Nabelbine, an antimitotic agent, and topotecan, a topoisomerase I inhibitor, exert radiosensitizing effects. A combination phase I study of paclitaxel and cisplatin was conducted in patients with previously untreated, unresectable stage III or IV non-small cell lung cancer. Twenty five assessable patients were entered. The most frequent adverse effects were leukopenia, neutropenia, and bilirubinemia. A pharmacokinetic study revealed no drug-drug interactions. The recommended doses were 180 mg/m² of paclitaxel in combined with 60 or 80 mg/m² of cisplatin. Other related clinical studies are listed.^(98-102)