Expression of Somatostatin Receptor Subtypes (SSTR-1-SSTR-5) in Pediatric Hematological and Oncological Disorders.

Hematological and oncological disorders represent leading causes of childhood mortality. Neuropeptide somatostatin (SST) has been previously demonstrated in various pediatric tumors, but limited information exists on the expression and characteristics of SST receptors (SSTR) in hematological and oncological disorders of children. We aimed to investigate the expression of mRNA for SSTR subtypes (SSTR-1-5) in 15 pediatric hematological/oncological specimens by RT-PCR. The presence and binding characteristics of SSTRs were further studies by ligand competition assay. Our results show that the pediatric tumor samples highly expressed mRNA for the five SSTR subtypes with various patterns. The mRNA for SSTR-2 was detected in all specimens independently of their histological type. A Hodgkin lymphoma sample co-expressed mRNA for all five SSTR subtypes. SSTR-3 and SSTR-5 were detected only in malignant specimens, such as rhabdomyosarcoma, Hodgkin lymphoma, acute lymphoblastic leukemia, and a single nonmalignant condition, hereditary spherocytosis. The incidence of SSTR-1 and SSTR-4 was similar (60%) in the 15 specimens investigated. Radioligand binding studies demonstrated the presence of specific SSTRs and high affinity binding of SST analogs in pediatric solid tumors investigated. The high incidence of SSTRs in hematological and oncological disorders in children supports the merit of further investigation of SSTRs as molecular targets for diagnosis and therapy.

Somatostatin Receptors as Molecular Targets in Human Uveal Melanoma.

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults, with an incidence of 4⁻5 cases per million. The prognosis of UM is very poor. In the present study, our aim was to investigate the expression of mRNA and protein for somatostatin receptor types-1, -2, -3, -4, -5 (SSTR-1⁻5) in human UM tissue samples and in OCM-1 and OCM-3 human UM cell lines by qRT-PCR, western blot and ligand competition assay. The mRNA for SSTR-2 showed markedly higher expression in UM tissues than SSTR-5. The presence of SSTRs was demonstrated in 70% of UM specimens using ligand competition assay and both human UM models displayed specific high affinity SSTRs. Among the five SSTRs, the mRNA investigated for SSTR-2 and SSTR-5 receptors was strongly expressed in both human UM cell lines, SSTR-5 showing the highest expression. The presence of the SSTR-2 and SSTR-5 receptor proteins was confirmed in both cell lines by western blot. In summary, the expression of somatostatin receptors in human UM specimens and in OCM-1 and OCM-3 human UM cell lines suggests that they could serve as a potential molecular target for therapy of UM using modern powerful cytotoxic SST analogs targeting SSTR-2 and SSTR-5 receptors.

Experimental therapy of doxorubicin resistant human uveal melanoma with targeted cytotoxic luteinizing hormone-releasing hormone analog (AN-152).

BACKGROUND: Cytotoxic analogs of LHRH (luteinizing hormone-releasing hormone) can be successfully used for the treatment of hormone-dependent cancers such as prostatic, ovarian, endometrial, but our knowledge about their effect on hormone-independent cancers such as human uveal melanoma (UM) is limited. Previously, we have demonstrated that 46% of UM express full-length LHRH receptors. This finding has led us to further examine the mechanism of action of LHRH receptor based targeted therapies in this malignancy. AIMS: In the present study we investigated the cellular uptake of doxorubicin (DOX) and cytotoxic LHRH analog AN-152 (AEZS-108, zoptarelin doxorubicin) on human UM cell lines (OCM3) and its DOX resistant form OCM3DOX320 by confocal laser scanning microscopy. The LHRH receptor expression was characterized by RT-PCR and immunocytochemistry. RESULTS: We were able to establish a new, stable and DOX resistant human UM cell line OCM3DOX320. Our results demonstrated the expression of splice variants and isoforms of receptor for LHRH in OCM3 UM cell line and its doxorubicin resistant form OCM3DOX320. It has been revealed by MTT assay that AN-152 inhibited cell proliferation in a dose dependent manner in OCM3DOX320 cells. Furthermore, receptor-mediated uptake of AN-152 was demonstrated using confocal laser scanning microscopy in both cell line. CONCLUSIONS: Our results suggest that the antiproliferative effect of AN-152 can be detected even if only LHRH receptor isoforms are expressed. Our study also demonstrates the LHRH receptor-mediated uptake of AN-152 in DOX resistant OCM3DOX320 cells. Our experiments provide new insights into a potential targeted therapy of UM and give further details about the accumulation of AN-152 in hormone-independent DOX-resistant cells expressing splice variants of the LHRH receptors.

Expression of miRNA-21 and miRNA-221 in clear cell renal cell carcinoma (ccRCC) and their possible role in the development of ccRCC.

AIM: Clear cell renal cell carcinoma (ccRCC) is the third most common urological cancer after prostate and bladder cancer but has the highest rate of mortality affecting over 40% of patients. microRNAs (miRNAs) are small noncoding RNAs that have become potential biomarkers and molecular targets for cancer treatment. Molecular markers such as miRNAs may have a role in the diagnosis of ccRCC. In this study, we examined the expressions of miRNA-21 and miRNA-221 in renal cancer patients׳ tumor and adjacent paired normal tissues investigating the possible role of these miRNAs in the development of ccRCC. MATERIALS AND METHODS: Renal tumors (n = 24) and paired normal renal tissue (n = 24) samples, obtained from the Department of Urology, University of Debrecen, were analyzed for miRNA-21 and miRNA-221 expressions with quantitative real-time polymerase chain reaction. RESULTS: miRNA-21 and miRNA-221 expressions were significantly up-regulated in tumor specimens compared to normal tissue (P<0.05). miRNA-21 and miRNA-221 showed coexpression pattern in 19 (79.2%) cases of tumor samples and 8 (33.3%) cases of paired normal renal tissues. Increased miRNA pattern showed a positive correlation with pathological status of the patients. CONCLUSIONS: Expression of oncogenic miRNA-21 and miRNA-221 in human ccRCC tumor tissue samples compared to adjacent nontumorous tissues might suggest that these miRNAs are involved in the development of ccRCC.