Primary Melanoma miRNA Trafficking Induces Lymphangiogenesis.

Melanoma, the deadliest cutaneous tumor, initiates within the epidermis; during progression, cells invade into the dermis and become metastatic through the lymphatic and blood system. Before melanoma cell invasion into the dermis, an increased density of dermal lymphatic vessels is observed, generated by a mechanism which is not fully understood. In this study, we show that, while at the primary epidermal stage (in situ), melanoma cells secrete extracellular vesicles termed melanosomes, which are uptaken by dermal lymphatic cells, leading to transcriptional and phenotypic pro-lymphangiogenic changes. Mechanistically, melanoma-derived melanosomes traffic mature let-7i to lymphatic endothelial cells, which mediate pro-lymphangiogenic phenotypic changes by the induction of type I IFN signaling. Furthermore, transcriptome analysis upon treatment with melanosomes or let-7i reveals the enhancement of IFI6 expression in lymphatic cells. Because melanoma cells metastasize primarily via lymphatic vessels, our data suggest that blocking lymphangiogenesis by repressing either melanosome release or type I IFN signaling will prevent melanoma progression to the deadly metastatic stage.

Comparison between Roche and Xpert in HIV-1 RNA quantitation: A high concordance between the two techniques except for a CRF02_AG subtype variant with high viral load titters detected by Roche but undetected by Xpert.

BACKGROUND: HIV-1 viral load (VL) testing is important to predict viral progression and to monitor the response to antiretroviral therapy. New HIV-1 VL tests are continuously introduced to the market. Their performance is usually compared to Abbott and/or Roche HIV-1 VL assays, as reference. The Xpert HIV-1 VL test was recently introduced, but its performance compared to Roche has not been sufficiently studied. OBJECTIVES: To compare the Xpert assay with Roche and to assess its use in the HIV clinical laboratory. STUDY DESIGN: A total of 383 plasma samples of HIV-1 infected patients previously tested by Roche, were retrospectively tested by Xpert to determine concordance between the two assays. Samples included a diversity of HIV-1 subtypes and a wide range of VLs. RESULTS: There was a high concordance between the two assays, except for a CRF02_AG subtype variant with high VL titters, that was detected by Roche but undetected by Xpert. The 5' long terminal repeat gene region of this virus, targeted by the Xpert assay, was amplified and sequenced. A 25 nucleotide insert was identified, but was unmatched to any known sequences of HIV-1. This particular insert, however could not explain the false-negativity by the Xpert assay. CONCLUSIONS: This study underlines the challenge to routine VL testing due to the high genetic diversity of HIV-1. Clinicians should, therefore be advised that a negative VL in cases where the clinical picture does not match the laboratory report, might in fact be, a false-negative result of the VL assay.