|ognizant Communication Corporation|
AN INTERNATIONAL JOURNAL
INCORPORATING ANTI-CANCER DRUG DESIGN
VOLUME 14, NUMBERS 4/5
Oncology Research, Volume 14, pp. 175-225
0965-0407/04 $20.00 + .00
Copyright © 2004 Cognizant Comm. Corp.
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Emerging Roles of Targeted Small Molecule Protein-Tyrosine Kinase Inhibitors in Cancer Therapy
John K. Smith, Naila M. Mamoon, and Roy J. Duhé
Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS 39216-4505
Targeted protein-tyrosine kinase inhibitors (PTKIs) comprise a new, rapidly evolving class of low molecular weight anticancer drugs. Two members of this class, imatinib (Gleevec®) and gefitinib (Iressa®), are currently approved for market use in the United States. This review discusses the scientific history behind these two PTKI drugs, including the role of the targeted kinase in cancer etiology, the biochemistry of selective inhibition, the evaluation of clinical efficacy, and the mechanisms whereby drug resistance has emerged. Other PTKIs undergoing clinical evaluation are also described, including epidermal growth factor receptor kinase inhibitors (erlotinib, PKI166, and CI-1033) and PTKIs designed to disrupt tumor vascularization (SU5416, SU6668, SU11248, PTK787, and ZD6474). How might one apply current knowledge to the efficient development of new agents that would target as-yet-unexploited oncogenic PTKs such as chimeric anaplastic leukemia kinases or Janus kinases? Ideally, the targets should contain structurally distinct drug interaction epitopes, although it is not necessary that these epitopes be unique to a single target, because effective drugs may inhibit multiple kinases involved in an oncogenic process. Oral availability is a highly desirable feature because daily oral administration can maintain a sustained efficacious plasma concentration, whereas intermittent parenteral administration may not. Perhaps most importantly, one must verify the presence of an appropriate molecular target on a case-by-case basis before selecting a patient for PTKI therapy. Thus, the development of molecularly targeted diagnostic tools will be crucial to the ultimate success of molecularly targeted PTKI therapy.
Key words: Protein-tyrosine kinase inhibitors (PTKIs); Targeted cancer therapy; Molecularly targeted PTKI therapy
Address correspondence to Roy J. Duhé, Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, MS, 39216-4505. Tel: (601) 984-1625; Fax: (601) 984-1637; E-mail: RDUHE@pharmacology.umsmed.edu
Inhibition of Angiogenesis by Salmosin Expressed In Vitro
Soo In Kim,1 Keun Sik Kim,1 Hong Sung Kim,1 Myoung Min Choi,1 Doo Sik Kim,2 Kwang Hoe Chung,3 and Yong Serk Park1
1Department of Biomedical Laboratory
Science and Institute of Health Science, Yonsei University, Wonju 220-710,
Republic of Korea
2Department of Biochemistry, College of Science, Yonsei University, Seoul 120-749, Republic of Korea
3Cardiovascular Research Institute and BK 21 Project for Medical Sciences, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea
Recently, salmosin, a novel snake venom-derived disintegrin containing the Arg-Gly-Asp (RGD) sequence, was reported to be both antiangiogenic and antitumorigenic. The antitumor activity was substantiated by in vivo administration of recombinant salmosin into mice bearing tumors. However, it was difficult to prepare functionally active recombinant salmosin and to maintain a therapeutically effective concentration of the protein in the circulatory system by daily injections. Hence, we have suggested that salmosin gene transfer mediated by cationic liposomes may be a practical alternative for cancer treatment. Plasmids encoding the salmosin gene were constructed and then transferred by means of cationic liposomes into transformed human embryonic kidney (HEK) 293 cells. The transfected genes were able to produce functionally active salmosin proteins in vitro. In fact, the expressed salmosin remarkably inhibited proliferation of bovine capillary endothelial (BCE) cells and effectively inhibited the migration of highly metastatic B16BL6 mouse melanoma cells. Neovascularization in chick chorio-allantoic membranes (CAM) and in Matrigel implanted subcutaneously into mice was greatly inhibited in the presence of the expressed salmosin. Based on these experimental results, we suggest that the antitumor effect induced by salmosin gene transfection may be due to the antiangiogenic activity of the expressed salmosin proteins.
Key words: Disintegrin; Salmosin; Antiangiogenesis; Cationic liposomes; Gene therapy
Address correspondence to Y. S. Park, Department of Biomedical Laboratory Science and Institute of Health Science, Yonsei University, Wonju 220-710, Republic of Korea. Tel: +82-33-760-2448; Fax: +82-33-763-5224; E-mail: email@example.com
Hydroxyurea-Induced Apoptosis in an EBV-Immortalized Lymphoblastoid Cell Line
Pauline Huyghe,1,2* Laurent Dassonneville,1* Pierre Fenaux,1,2** and Christian Bailly1
1INSERM U-524, Institut de Recherches
sur le Cancer de Lille, 1 Place de Verdun, 59045 Lille cedex, France
2Service des Maladies du Sang, Laboratoire d'Hématologie, CHU Lille
Hydroxyurea (HU) is an inhibitor of nucleotide synthesis extensively used to control the chronic phase of myeloid leukemia. This antimetabolite has been employed in the clinic for several decades but in recent years the leukemogenic potential of HU has been suspected. In the present study, a B-lymphoblastoid cell line transformed by the Epstein-Barr virus was used to investigate the apoptotic effects of HU and delineate some of the molecular pathways implicated in the cytotoxic action. The cell line, characterized by immunophenotyping, cytogenetic and fluorescence in situ hybridization (FISH) studies, showed no chromosomal abnormalities, even after a prolonged exposure to HU. Different flow cytometry assays were used to measure HU-induced impairment of the cell cycle, inhibition of DNA synthesis, and the occurrence of apoptosis. The treatment with HU leads to the appearance of a hypo-diploid DNA content peak (sub-G1) characteristic of the apoptotic cell population. The drug also induces a cell block in S phase as measured by 5-bromo-2´-deoxyuridine (BrdU) incorporation. Inhibition of DNA synthesis precedes induction of apoptosis by HU. A drug-induced loss of plasma membrane asymmetry was characterized by flow cytometry using annexin V-FITC to stain phosphatidylserine residues. The implication of the antiapoptotic protein Bcl-2 and the tumor suppressor p53 in the development of HU-mediated apoptosis was also evidenced. The drug appears to promote cell death by regulating the expression levels of these two proteins. Different criteria define the apoptotic response of the lymphoblastoid cells to the treatment with HU. However, the extent of drug-induced cell death is limited, and no DNA fragmentation and no activation of the caspase cascade was observed in this model. Beyond the specific interest in HU-induced apoptosis, the work reported here illustrates the utility of the EBV immortalization process to investigate the pharmacological activity of specific drugs from clinical samples.
Key words: Hydroxyurea; Apoptosis; Cell cycle; p53; Bcl-2
Address correspondence to Dr. Christian Bailly, INSERM U-524, Institut de Recherches sur le Cancer de Lille, 1 Place de Verdun, 59045 Lille cedex, France. Tel: +33 320 16 92 18; Fax: +33 320 16 92 18 29; E-mail: firstname.lastname@example.org
*These two authors contributed equally to the work.
**Present address: Service d'hématologie clinique, Hôpital Avicenne, 125 Route de Stalingrad, 93009 Bobigny, France.
Synthesis and In Vitro Cytotoxicity Studies of Novel L-Tryptophan-Polyamide Conjugates and L-Tryptophan Dimers Linked With Aliphatic Chains and Polyamides
Rohtash Kumar, Dinesh Rai, and J. William Lown
Department of Chemistry, University of Alberta, Edmonton, AB, Canada, T6G 2G2
The synthesis and biological evaluation of novel L-tryptophan pyrrole, imidazole polyamide conjugates (16-21), L-tryptophan-glycosylated pyrrole polyamide conjugates (28-30), L-tryptophan dimers (37-42) with straight carbon links of varying length, and L-tryptophan dimers (68-73) linked with pyrrole and imidazole polyamide from both sides by a flexible methylene chain of variable length are described. The compounds were prepared with varying numbers of pyrrole- and/or imidazole-containing polyamides and glycosylated pyrrole polyamides to determine the structural requirements for optimal in vitro antitumor activity. The compounds listed in Table 1 have been evaluated in a three cell line, one dose primary anticancer assay. The compounds listed in Table 2 have been evaluated against nine panels of 60 human cancer cell lines including leukemia, non-small cell lung cancer, colon cancer, CNS cancer, melanoma, ovarian cancer, renal cancer, prostate cancer, and breast cancer. It is observed from the initial cytotoxic data (Table 1) that compounds 16-19, 28-30, 68-69, and 71-73 have varying cytotoxic potencies against the three cancer cell lines. It is also observed, from the biological data from Table 2 for compounds 20-21, 37-42, and 70 against the 60 different tumor cells, that the L-tryptophan dimers 37-42 linked by a different number of carbon chains are more active than the L-tryptophan dimers linked by pyrrole or imidazole polyamides. The cytotoxic potency in tryptophan dimers, linked by a different number of carbon atoms increased the number of carbons between the two L-tryptophan rings.
Key words: L-Tyrptophan; L-Tryptophan-polyamide conjugates; L-Tryptophan dimers; Cytotoxic potency
Address correspondence to J. William Lown, Department of Chemistry, University of Alberta, Edmonton, AB, Canada, T6G 2G2. Tel: (780) 492-3646; Fax: (780) 492-8231; E-mail: Lynne.email@example.com