Knocking down AR promotes osteoblasts to recruit prostate cancer cells by altering exosomal circ-DHPS/miR-214-3p/CCL5 pathway.

ABSTRACT: Tumor-derived exosomes have been shown to play a key role in organ-specific metastasis, and the androgen receptor regulates prostate cancer (PCa) progression. It is unclear whether the androgen receptor regulates the recruitment of prostate cancer cells to the bone microenvironment, even bone metastases, through exosomes. Here, we found that exosomes isolated from PCa cells after knocking down androgen receptor (AR) or enzalutamide treatment can facilitate the migration of prostate cancer cells to osteoblasts. In addition, AR silencing or treatment with the AR antagonist enzalutamide may increase the expression of circular RNA-deoxyhypusine synthase (circ-DHPS) in PCa cells, which can be transported to osteoblasts by exosomes. Circ-DHPS acts as a competitive endogenous RNA (ceRNA) against endogenous miR-214-3p to promote C-C chemokine ligand 5 (CCL5) levels in osteoblasts. Increasing the level of CCL5 in osteoblasts could recruit more PCa cells into the bone microenvironment. Thus, blocking the circ-DHPS/miR-214-3p/CCL5 signal may decrease exosome-mediated migration of prostate cancer cells to osteoblasts.

Tetrandrine suppresses proliferation, induces apoptosis, and inhibits migration and invasion in human prostate cancer cells.

Tetrandrine (TET), a traditional Chinese medicine, exerts remarkable anticancer activity on various cancer cells. However, little is known about the effect of TET on human prostate cancer cells, and the mechanism of function of TET on prostate cancer has not yet been elucidated. To investigate the effects of TET on the suppression of proliferation, induction of apoptosis, and inhibition of migration and invasion in human prostate cancer cell lines, DU145 and PC-3. Inhibition of growth was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and clone formation assay, and flow cytometry analysis was performed to detect the induction of apoptosis. Activation of poly (ADP-ribose) polymerase, caspase-3, Akt, phospho-Akt, Bcl-2, and Bax was analyzed by Western blotting. Wound healing assay and transwell migration assay were used to evaluate the effect of TET on migration and invasion of cancer cells. TET inhibited the growth of DU145 and PC-3 cells in a dose- and time-dependent manner. Cell cloning was inhibited in the presence of TET in DU145 and PC-3 cells. TET suppressed the migration of DU145 and PC-3 cells. Transwell invasion assay showed that TET significantly weakened invasion capacity of DU145 and PC-3 cells. TET exhibited strong inhibitory effect on proliferation, migration, and invasion of prostate cancer cells. In addition, TET induced apoptosis in a dose-dependent manner by activating the caspase cascade and inhibiting phosphoinositide 3-kinase-Akt signal pathway. The accumulating evidence suggests that TET could be a potential therapeutic candidate against prostate cancer in a clinical setting.

[Establishment of an animal model of prostate cancer metastasis to the lung traced by AsRed2].

OBJECTIVE: To establish an animal model of prostate cancer (PCa) metastasis to the lung using PCa PR7 (PCa PC-3 cells stably expressing red fluorescent protein AsRed2) cell lines that can be monitored by in vivo fluorescence imaging technology. METHODS: MTT and Transwell assay were used to compare the abilities of proliferation, migration and invasion of PC-3 and PR7 cells. Twenty BALB/c nude mice were equally randomized to 4 groups to receive tail vein injection of PR7 cell suspension at the concentration of 1 x 107/ml (group A), 2.5 x 107/ml (group B), 5 x 107/ml (group C) and 2.5 x 107/ml followed by the same dose 1 week later (group D). PCa metastasis to the lung was then monitored by in vivo fluorescence imaging technology at the end of 2, 4, 6 and 8 weeks. RESULTS: There were no statistically significant differences between PC-3 and PR7 cells in their abilities of proliferation, migration and invasion (P > 0.05). At the end of 4 weeks, lung metastasis was observed in 40% of the mice in group D, and at the end of 8 weeks, it was detected in 20% in group A, 60% in group B, 100% in group C, and 100% in group D, all confirmed by pathological examination. CONCLUSION: The animal model of PCa metastasis to the lung that can be monitored by in vivo fluorescence imaging technology was established successfully by tail vein injection of PR7 cells carrying red fluorescent protein.

[GLI-1 is involved in EGF-regulated enhancement of the invasiveness of prostate cancer ARCaP(E) cells in vitro].

OBJECTIVE: To investigate the role of the hedgehog (HH) signaling pathway transcription factor glioma-associated oncogene hoinolog 1 (GLI-1) in EGF-regulated enhancement of the invasiveness of the prostate cancer ARCaP(E) cell line in vitro. METHODS: The expressions of EGFR and GLI-1 in prostate cancer ARCaP(E) cells were analyzed by immunofluorescence staining. ARCaP(E) cells were treated with EGF at 100 ng/ml, followed by detection of the changes in cell morphology and invasiveness, as well as in the expressions of p-ERK, ERK and GLI-1. Migration transwell assay was used to determine the effects of 100 ng/ml EGF and GLI-1 antagonist GANT61 on the invasiveness of the ARCaP(E) cells. RESULTS: Both EGFR and GLI-1 were expressed in the ARCaP(E) cells. EGF induced morphological transition of epithelial-like ARCaP(E) cells to mesenchymal-like cells, increased their in vitro invasiveness, and significantly upregulated the expressions of p-ERK and GLI-1 in the ARCaP(E) cells (P<0.05). GANT61 significantly inhibited the in vitro invasiveness of the ARCaP(E) cells and reduced the enhancing effect of EGF on their invasiveness (P<0.05). CONCLUSION: The results from ARCaP(E) cells shed light on the cross-talk of the HH pathway with the EGF/ERK signaling pathway. GLI-1 might be responsible for EGF-regulated enhancement of the invasiveness of ARCaP(E) cells in vitro.