ABSTRACT
Uveal melanoma is the most common primary intraocular malignancy in adults, with a very high mortality rate due to frequent liver metastases. Consequently, the therapy of uveal melanoma remains a major clinical challenge and new treatment approaches are needed. For improving diagnosis and designing a rational and effective therapy, it is essential to elucidate molecular characteristics of this malignancy. The aim of this study therefore was to evaluate as a potential therapeutic target the expression of luteinizing hormone-releasing hormone (LHRH) receptor in human uveal melanoma. The expression of LHRH ligand and LHRH receptor transcript forms was studied in 39 human uveal melanoma specimens by RT-PCR using gene specific primers. The binding charachteristics of receptors for LHRH on 10 samples were determined by ligand competition assays. The presence of LHRH receptor protein was further evaluated by immunohistochemistry. The expression of mRNA for type I LHRH receptor was detected in 18 of 39 (46%) of tissue specimens. mRNA for LHRH-I ligand could be detected in 27 of 39 (69%) of the samples. Seven of 10 samples investigated showed high affinity LHRH-I receptors. The specific presence of full length LHRH receptor protein was further confirmed by immunohistochemistry. A high percentage of uveal melanomas express mRNA and protein for type-I LHRH receptors. Our results support the merit of further investigation of LHRH receptors in human ophthalmological tumors. Since diverse analogs of LHRH are in clinical trials or are already used for the treatment of various cancers, theseanalogs could be considered for the LHRH receptor-based treatment of uveal melanoma.
Subject(s)
Melanoma/metabolism , Receptors, LHRH/biosynthesis , Uveal Neoplasms/metabolism , Adult , Aged , Aged, 80 and over , Female , Humans , Immunohistochemistry , Male , Melanoma/genetics , Middle Aged , RNA, Messenger/biosynthesis , RNA, Messenger/genetics , Receptors, LHRH/genetics , Uveal Neoplasms/geneticsABSTRACT
Despite significant improvement in the diagnosis and treatment of various human carcinomas, the 5-year survival rate for lung cancer remains below 20%. Vasoactive intestinal peptide (VIP) is an important neuropeptide in the control of lung physiology, and exerts its functions mainly through two receptor subtypes, VPAC1 and VPAC2. Receptors for VPAC1 and VPAC2 are present in human lung cancer cells, but very limited information exists about the mRNA expression of these VIP receptor subtypes in lung cancer specimens. The aim of the present study was to investigate by RT-PCR the mRNA expression of the VPAC1 and VPAC2 receptors in surgical specimens of 43 human lung cancer specimens and 7 normal lung samples. mRNA expression of the VPAC1 receptor was detected in 51% of the tumor specimens, while the incidence of mRNA expression for VPAC2 was 46%. Twenty-one percent of the tumor samples expressed only the VPAC1 receptor and 16% displayed only the VPAC2 receptor, while 13 samples (30%) expressed neither subtype. Thirteen cancer tissue specimens (30%), expressed both of these VIP receptor subtypes. Three normal lung tissue specimens also displayed gene expression for VPAC1 and/or VPAC2 receptors. Our results support the additional investigation of the role of VIP and its receptors in human lung cancer and suggest a further development of VIP analogs for therapeutic and imaging purposes in this malignancy.
