Screening of Therapeutic Targets for Canine Mast Cell Tumors from a Variety of Kinase Molecules

Abstract

ABSTRACT. Options of systemic treatment for canine MCT have been still limited and most canine cases with MCTs eventually undergo relapses even after achievement of a remission. Thus additional therapies are required to establish for the tumor. To identify the novel candidate therapeutic targets for canine MCT, the mRNA expression and phosphorylation statuses of several receptor or non-receptor kinases as well as the inhibitory effect of 95 specific inhibitors on the growth were assessed in three canine MCT cell lines (HRMC, VIMC1 and CMMC1). Among the 14 targets, the mRNAs of 11, 7 and 7 kinases were amplified in HRMC, VIMC1 and CMMC1, respectively. The mRNAs of VEGFR3, PDGFR, SRC, YES, LCK and FYN were detected in all cell lines. The phosphorylation of 12, 8 and 7 kinases was observed by using specific antibody arrays in HRMC, VIMC1 and CMMC1, respectively. DTK, EPHB6, AMPK1, CREB, STAT5a and STAT5b were phosphorylated in all cell lines. The 10, 9 and 17 inhibitors exhibited the biological activity against the growth of HRMC, VIMC1 and CMMC1, respectively. Only three inhibitors such as SB218078 (for Chk1), PDGF RTK inhibitor IV (for PDGFR) and radicicol (for Hsp90) suppressed the growth of all three cell lines. The present study indicated that several kinases, such as Chk1, PDGFR and Hsp90, could be used as therapeutic targets in the treatment for canine MCT. Further studies and clinical trials are warranted to apply the inhibitors for the treatment of the tumor.KEY WORDS: canine, cell line, kinases, molecular-targeted therapy, screening method.J. Vet. Med. Sci. 73(10): 1295-1302, 2011 Mast cell tumor (MCT) is one of common skin tumors in dogs and accounts for 7 to 21% of all canine cutaneous tumors [35]. Canine MCTs also arise in extracutaneous sites (visceral MCT) including the conjunctiva, salivary gland, nasopharynx, larynx, oral cavity, gastrointestinal tract, urethra and spine. The clinical behavior of canine MCTs is variable, ranging from slight to severe [7]. Based on the World Health Organization clinical staging and histological grading, treatment for canine MCTs is selected from surgical resection, irradiation, chemotherapy or combination of those [35]. In addition to the conventional therapy, the clinical efficasy of several tyrosine kinase inhibitors (TKIs) such as toceranib, masitinib and imatinib for canine MCT cases has been studied [10,12,22].Several studies revealed that approximately 15 to 40% of canine MCTs contained mutations of KIT gene encoding type III receptor protein tyrosine kinase, c-Kit receptor [15,35]. The several mutations of KIT in canine MCT cases cause constitutive autophosphorylation and activation of cKit receptor without binding of the ligand [15,21,23]. Some studies reported that the TKIs could inhibit c-Kit receptor activation and proliferation of canine MCT cells [9,16,26]. A clinical study reported that canine MCT cases harboring KIT mutation responded to treatment with imatinib [12]. Other studies indicated that canine MCT cases with KIT mutations were more likely t...

Receptor Tyrosine Kinase Expression Profiles in Canine Cutaneous and Subcutaneous Mast Cell Tumors

“…While it possible that other forms of KIT dysregulation were inhibited by toceranib (eg, other c- KIT mutations, autocrine or paracrine signaling, or spontaneous homodimerization of overexpressed receptor), an alternative possibility is that clinical responses may have been due to toceranib’s inhibition of RTKs other than KIT, such as vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptor (PDGFR). 27 These RTKs are implicated in the progression of some animal 1,6,9,21,36,42 and human 4,7,8,16,18,32 neoplasms and are also key contributors to tumor angiogenesis. 12,17,29 Drugs that inhibit these RTKs could disrupt not only neoplastic cells but stromal interactions, vascularity, and metastatic niches.…”

Studying the DNA damage response pathway in hematopoietic canine cancer cell lines, a necessary step for finding targets to generate new therapies to treat cancer in dogs

“…Upregulation of Chk1 has been proposed as a target for anticancer therapies. Different studies have confirmed Chk1 inhibitors acting as apoptosis inducers in various human and canine tumor cells, indicating, for example, proliferation decrease in human neoplastic B-cells and mast tumor cell (MTC) canine cell lines ( 68 , 69 ). Currently, there are several Chk1 inhibitors in phase II of clinical trials and the results in human cancers seem promising ( 8 , 70 ).…”

An Update on Molecular Pathways Regulating Vasculogenic Mimicry in Human Osteosarcoma and Their Role in Canine Oncology

“…An extensive knowledge concerning PDGF/PDGFR axis is available in veterinary literature. This molecular axis has been investigated as endothelial marker ( 91 ), in wound healing ( 92 ), spontaneous canine astrocytoma ( 93 ), fibrosarcoma ( 94 ), squamous cell carcinoma ( 95 ), lymphoma ( 96 ), prostate cancer ( 97 ), hemangioma and hemangiosarcoma ( 98 ), melanoma ( 99 ), mast cell tumors ( 100 ), hepatocellular carcinoma ( 101 ), mammary tumors ( 102 ), and nervous system tumors ( 103 , 104 ).…”