Bufalin Inhibits Prostate Cancer Bone Metastasis Through HOTAIR

Objectives: Prostate cancer bone metastasis is a serious threat to health and life in male,the prognosis is still poor,so there is an urgent need to explore new effective drugs.Bufalin,the extract from Chansu,has a broad-spectrum anti-tumor effect,but there was no research of its effect on the invasion and metastasis of prostate cancer.This study aimed to study the effects and mechanisms of bufalin on bone metastasis of prostate cancer.Methods: Firstly,the effects of bufalin on the migration and invasion of castrated resistant prostate cancer cells DU145 and PC3 were studied by cell migration and transwell invasion assay.The expression of HOX transcript antisense RNA(HOTAIR)was found to be significantly down-regulated after bufalin treatment using microarray analysis of the long non-coding RNA(lnc RNA)profile.The target gene of HOTAIR was predicted by bioinformatics analysis and verified by experiments.Secondly,the role of HOTAIR in prostate cancer bone metastasis was explored through experimental and clinical studies: in experimental study,prostate cancer cell and osteoblast-like cell MG-63 were co-cultured to simulate the bone metastasis microenvironment,the effects of overexpression of HOTAIR on proliferation activity of co-cultured osteoblast-like cell and its secreted cytokines were observed;in clinical research we detected the expression of HOTAIR in paraffin sections of primary prostate cancer and bone metastasis tissues using in situ hybridization assay,and detected the levels of serum HOTAIR and bone metabolic markers of prostate cancer patients with or without bone metastasis.Then we compared the HOTAIR levels between primary tumors and bone metastases,analyzed the correlation between HOTAIR and clinicopathological characteristics,analyzed the correlation between serum levels of HOTAIR and bone metabolic markers,and explore the effeciency of serum HOTAIR as a biomarker of prostate cancer bone metastasis.Results: Bufalin significantly suppressed the migration and invasion of DU145 and PC3 cells,the mechanism was inhibiting the HOTAIR/mi R-520b/FGFR1 pathway.Prostate cancer cell with overexpressed HOTAIR can enhance osteoblast-like cell proliferation activity in co-culture environment,can up-regulate expression of receptor activator of nuclear factor κB ligand(RANKL)and down-regulate expression of osteoprotegerin(OPG)in osteoblast-like cell,subsequently may promote osteoclastogenesis and bone metastasis by regulating the RNAKL/RANK/OPG pathway.The expression of HOTAIR in prostate cancer bone metastatic tissues was significantly higher than that in primary tumors and correlated with serum PSA levels.Serum HOTAIR levels in prostate cancer patients were positively correlated with bone metabolic markers,and had high sensitivity and specificity for diagnosing prostate cancer bone metastasis.Conclusions: Bufalin inhibits the invasion and metastasis of prostate cancer by down-regulating HOTAIR.HOTAIR is closely related to prostate cancer bone metastasis,it promotes prostate cancer bone metastasis both by enhancing the migration and invasion ability of cancer cell and regulating bone metastasis microenvironment.Serum HOTAIR level can be used as a reasonable biomarker for the diagnosis of prostate cancer bone metastasis.