The Expression Of MicroRNA-181b-5p In Kaposi’s Sarcoma And Effects On Biological Characteristic Of Human Kaposi’s Sarcoma Cell Line SLK

Obiective:To compare miR-181b-5p expression in Kaposi’s sarcoma and adjacent normal tissue and to explore the clinical significance of such difference. miR-181b-5p mimics and inhibitors were transfected into Kaposi’s sarcoma cell line SLK through liposomal transfection. The effect of miR-181b-5p on SLK cell proliferation, apoptosis, migration, invasion and a series of biological activities were studied to provide theoretical basis for further investigation on the role of miR-181b-5p in the pathogenesis of Kaposi’s sarcoma. Methods:(A) Quantitative PCR was performed on18pairs of frozen Kaposi’s sarcoma and adjacent normal tissues to determine miR-181b-5p expression; statistic analysis was made on miR-181b-5p expressions in different age, sex, pathological types, HIV infection, HHV-8infection,co-infection of HIV and HHV-8,disease duration,lesion sizes and systemic lesion types (B) Human Kaposi’s sarcoma cell line SLK was transfected by liposomes, and the optimal transfection concentration and optimal transfection time were determined by transfection with different concentrations of positive control followed by MTT assay to plot a growth curve. After miR-181b-5pminic or inhibitor was transfected,SLK cell proliferation was assessed by MTT assay;apoptosis rate of each groupwas determined by flow cytometry after48hours after transfection.(C) After miR-181b-5pminic or inhibitor was transfected, cell migration and invasion was determined by transwell assay followed by hematoxylin staining after24hours. Results: Quantitative PCR showed that miR-181b-5p expression in Kaposi’s sarcoma significantly increased to about3.10fold of that in adjacent tissues; the ratio showedno significant correlation with age, sex, HIV infection,HHV-8infection, co-infecti on of HIV and HHV-8, disease duration, lesion size and systemic lesion type, butthe ratio in patch phase of Kaposi’s sarcoma showed significant difference with that in the plaque phase and nodular phase. MTT assay showed that, the optimal transfection concentration was94ng/L and optimal time was48hours;Compared tothe negative control group, proliferative capacity of miR-181b-5p significantly increased after transfection with miR-181b-5p mimics(P＜0.01)and significantly decreased after transfection with miR-181b-5p inhibitor(P＜0.01). Flow cytometry showedthat, apoptosis rate of the SLK cells has significantly decreased after transfectionwith miR-181b-5p mimics(5.5±0.6)%compared to that of corresponding negativecontrol(7.6±0.4)%. Apoptosis rate of the SLK cells has significantly increased after transfection with miR-181b-5p inhibitor(14.8±1.0)compared to that of corresponding negative control(7.8±0.5)%. Transwell migration assay results showed that number of migrated cell in the group treated with miR-181b-5p mimics was184±9, significantly higher than that of control group (151±11), suggesting that miR-181b-5p mimics significantly increased cell migration ability.While number of migrated cell in the group treated with miR-181b-5p inhibitor(105±10)significantly reduced. Transwell invasion assay showed that cell number of miR-181b-5p mimics group(48±5)significantly increased compared to negative control group (35±6) suggesting increased invasiveness. And cell numbers of miR-181b-5p inhibitor group(23±4)significantly reduced suggesting decreased invasiveness. It was observed that invasiveness of Kaposi’s sarcoma cells is weak, and large number of cells are needed to get enough cell counts. Conclusion:miR-181b-5p might be involved in tumorigenesis of Kaposi’s sarcoma and has the potential to be one of potential molecular diagnostic indicators.Transfection with miR-181b-5p mimics/inhibitors significantly affected SLK cell proliferation, apoptosis, invasion and migration. Further researches on biological characteristics of miR-181b-5p and validation of the associatedtarget genes are therefore of great significance.