Knockdown of Skp2 by siRNA inhibits melanoma cell growth in vitro and in vivo.

BACKGROUND: Low levels of p27Kip1 expression are associated with poor prognosis in various malignancies including malignant melanoma. Recently, it has been reported that S phase kinase-interacting protein 2 (Skp2), the specific ubiquitin ligase subunit that targets p27Kip1 for degradation, was overexpressed and was inversely related to p27Kip1 levels in malignant melanoma with poor prognosis. OBJECTIVE: We investigated whether small interfering RNA (siRNA)-mediated gene silencing of Skp2 can be employed in order to inhibit p27Kip1 down-regulation and suppress melanoma cell growth as a consequence in vitro and in vivo. METHODS: We constructed a plasmid vector, which synthesizes siRNAs to determine the effects of decreasing the high constitutive levels of Skp2 protein in melanoma cells. Western blot and real-time RT-PCR were performed to examine the decreases of Skp2 protein and mRNA in vitro. Furthermore, melanoma cells were injected into the back of nude mice subcutaneously to examine the suppression of tumorigenicity targeting Skp2 gene silencing in vivo. RESULTS: Skp2 protein was decreased and the p27Kip1 protein was accumulated in Skp2 siRNA transfected melanoma cells. Skp2 siRNA inhibited the cell growth of melanoma cells in vitro. Moreover, Skp2 siRNA also suppressed tumor proliferation in vivo. CONCLUSION: Our results suggest that siRNA-mediated gene silencing of Skp2 can be a potent tool of cancer gene therapy for suppression of p27Kip1 degradation in malignant melanoma.

Hydroa vacciniforme-like eruptions in a patient with chronic active EB virus infection.

We report a case of chronic active Epstein-Barr (EB) virus infection (CAEBV) associated with skin eruptions mimicking hydroa vacciniforme (HV) in a 4-year-old boy. The patient had repeated episodes of vesiculo-necrotic eruptions on the face, scalp, and bilateral forearms one year before the first visit to our department. General symptoms including fever, hepatosplenomegaly, abnormal liver function, and cervical lymph node swelling were noted three months before the first visit. At the first visit, small, bean-sized, erythemic papules with central necrosis were observed on the face and anterior chest wall. Thumb-sized ulcers with crust were present on the bilateral forearms. Histopathological examination of an erythematous lesion in the submandibular area revealed parakeratosis with a thick crust, mild spongiosis in the epidermis, and a dense infiltration of lymphoid cells into the dermis and perivascular space. Laboratory examination showed EBNA x 40, EBV VCA IgG x 1,280, and EBV DNA (PCR) 8 x 10(4). EBV-encoded small nuclear RNA (EBER) positive cells were detected in the dermis by an in situ hybridization (ISH) method. Large granular lymphocytes (65%) with the NK cell phenotype were found in the peripheral blood. A real time PCR method showed 171,741 copies/ micro g DNA in CD 16 positive cells. Although latent EBV infection-associated eruptions have been documented, detailed skin manifestations in CAEBV are less well known.