miR-656-3p inhibits melanomas in vitro and in vivo by inducing senescence via inhibiting LMNB2.

BACKGROUND: Ultra-Violet Radiation (UVR) is the most significant exogenous contributor to skin aging. UVB causes the senescence of melanocytes, which results in a permanent arrest in the proliferative process. Senescence is also regarded as a physiological tumor-suppressing mechanism of normal cells. However, the mechanism of the relationship between melanocyte senescence and melanoma was not sufficiently clarified. METHODS: Melanocytes and melanoma cells were irradiated with UVB for the indicated time. The miRNA expression profile of melanocytes were obtained by miRNA sequencing and confirmed by real-time PCR. Cell count kit-8 assays, cell cycle assays were also employed to explore the effect of miR-656-3p and LMNB2 on senescence. Dual-luciferase reporter assays were applied to determine the miRNA targets. Finally, a xenograft model and a photoaging model of mice were conducted to verified the function of miR-656-3p in vivo. RESULTS: Melanoma cells did not alter into a senescence stage and the expressions of miR-656-3p had no significant changes under the same intensity of UVB radiation. miR-656-3p appeared to be upregulated in melanocytes rather than melanoma cells after UVB radiation. miR-656-3p could promote the photoaging of human primary melanocytes by targeting LMNB2. Finally, overexpression of miR-656-3p significantly induced senescence and inhibited the growth of melanomas in vitro and in vivo. CONCLUSION: Our work not only demonstrated the mechanism by which miR-656-3p induced the senescence of melanocytes but also proposed a treatment strategy for melanomas by using miR-656-3p to induce senescence.

"Red Spitz Tumor" on the Ear: Case Report and Review of the Literature.

Spitz nevus (SN) is a benign melanocytic lesion with cytologic and architectural atypia. It is sometimes difficult to distinguish SNs from atypical Spitz tumor (AST), Spitz melanoma, or conventional melanoma. SNs frequently develop in Caucasians and appear on the skin of the head and lower extremities. Lesions on the ear in Asian populations are rare. Here, we report a "red Spitz tumor" on the ear of a Chinese 18-year-old boy. Dermoscopic examination revealed possibly malignant features presented as polymorphous vessels along with central white area, pseudo-network depigmentation and atypical peripheral globular pattern. The results of histopathological examination strongly suggested that the neoplasm was a compound SN and no recurrences or metastases occurred during 1-year follow-up post-surgery. Further, we review the literature on 4 previously reported cases of SN on the ear and summarize the main points of SN diagnosis and differential diagnosis with atypical Spitz tumors and melanoma.