ADAMTS1 alters blood vessel morphology and TSP1 levels in LNCaP and LNCaP-19 prostate tumors.

BACKGROUND: Decreased expression of the angiogenesis inhibitor ADAMTS1 (ADAM metallopeptidase with thrombospondin type 1 motif, 1) has previously been reported during prostate cancer progression. The aim of this study was to investigate the function of ADAMTS1 in prostate tumors. METHODS: ADAMTS1 was downregulated by shRNA technology in the human prostate cancer cell line LNCaP (androgen-dependent), originally expressing ADAMTS1, and was upregulated by transfection in its subline LNCaP-19 (androgen-independent), expressing low levels of ADAMTS1. Cells were implanted subcutaneously in nude mice and tumor growth, microvessel density (MVD), blood vessel morphology, pericyte coverage and thrombospondin 1 (TSP1) were studied in the tumor xenografts. RESULTS: Modified expression of ADAMTS1 resulted in altered blood vessel morphology in the tumors. Low expression levels of ADAMTS1 were associated with small diameter blood vessels both in LNCaP and LNCaP-19 tumors, while high levels of ADAMTS1 were associated with larger vessels. In addition, TSP1 levels in the tumor xenografts were inversely related to ADAMTS1 expression. MVD and pericyte coverage were not affected. Moreover, upregulation of ADAMTS1 inhibited tumor growth of LNCaP-19, as evidenced by delayed tumor establishment. In contrast, downregulation of ADAMTS1 in LNCaP resulted in reduced tumor growth rate. CONCLUSIONS: The present study demonstrates that ADAMTS1 is an important regulatory factor of angiogenesis and tumor growth in prostate tumors, where modified ADAMTS1 expression resulted in markedly changed blood vessel morphology, possibly related to altered TSP1 levels.

N-cadherin increases after androgen deprivation and is associated with metastasis in prostate cancer.

Androgen-deprivation therapy (ADT) is the standard treatment for metastatic prostate cancer. One factor that has been implicated in the metastatic process is the cell adhesion molecule N-cadherin. In this study, we investigated if the expression of N-cadherin was influenced by androgen deprivation and was associated with metastasis in prostate cancer. The effect of androgen deprivation on N-cadherin expression was initially studied in androgen-dependent (AD) LNCaP and androgen-independent (AI) LNCaP-19 and PC-3 prostate cancer cell lines. Expression of N-cadherin increased in the absence of androgens in AI LNCaP-19 primary tumors and metastases and also in vitro, but not in AI PC-3 tumors, indicating a possible involvement of the androgen receptor in the regulation of N-cadherin. N-cadherin was absent in AD LNCaP tumors. No clear associations between N-cadherin and factors related with epithelial-mesenchymal transition or neuroendocrine differentiation could be established. In addition, N-cadherin was evaluated by immunohistochemistry in human prostate tumors. Expression of N-cadherin was more frequently found in tumors from patients treated with ADT than in tumors from patients with no prior hormonal treatment. N-cadherin expression was also associated with metastasis and Gleason score. Furthermore, increased N-cadherin was detected in prostate cancer biopsies already 3 months after initiation of ADT when tumors were in a regressed state. In summary the results indicate that androgen deprivation induces N-cadherin in prostate tumors. Moreover, N-cadherin was increased in castration-resistant tumors in patients with established metastases. This might indicate that castration induces molecular alterations in the tumor cells, resulting in a more invasive and metastatic phenotype.

The prostatic environment suppresses growth of androgen-independent prostate cancer xenografts: an effect influenced by testosterone.

BACKGROUND: Interactions between prostate cancer cells and their surrounding stroma play an important role in the growth and maintenance of prostate tumors. To elucidate this further, we investigated how growth of androgen-dependent (AD) LNCaP and androgen-independent (AI) LNCaP-19 prostate tumors was affected by different microenvironments and androgen levels. METHODS: Tumor cells were implanted subcutaneously and orthotopically in intact and castrated immunodeficient mice. Orthotopic tumor growth was followed by magnetic resonance imaging (MRI). Gene expression in the tumors was evaluated by means of microarray analysis and microvessel density (MVD) was analyzed using immunohistochemistry. RESULTS: The results showed that LNCaP-19 tumors grew more rapidly at the subcutaneous site than in the prostate, where tumors were obviously inhibited. Castration of the mice did not affect ectopic tumors but did result in increased tumor growth in the prostatic environment. This effect was reversed by testosterone treatment. In contrast to LNCaP-19, the LNCaP cells grew rapidly in the prostate and castration reduced tumor development. Gene expression analysis of LNCaP-19 tumors revealed an upregulation of genes, inhibiting tumor growth (including ADAMTS1, RGS2 and protocadherin 20) and a downregulation of genes, promoting cell adhesion and metastasis (including N-cadherin and NRCAM) in the slow-growing orthotopic tumors from intact mice. CONCLUSIONS: The results show that the prostatic environment has a varying impact on AD and AI tumor xenografts. Data indicate that the androgen-stimulated prostatic environment limits growth of orthotopic AI tumors through induction of genes that inhibit tumor growth and suppression of genes that promote cell adhesion and metastasis.

Differential expression of angiopoietin-2 and vascular endothelial growth factor in androgen-independent prostate cancer models.

OBJECTIVE: To investigate the relationship between microvessel density (MVD), blood vessel morphology and the expression of angiopoietin (Ang)-1, Ang-2, tyrosine kinase with immunoglobulin and epidermal growth factor homology domains (Tie)-2, and vascular endothelial growth factor (VEGF) in androgen-dependent (AD) and androgen-independent (AI) prostate cancer models, to gain insight into the regulation of angiogenesis at different stages of prostate cancer. MATERIALS AND METHODS: MVD and blood vessel morphology were evaluated by CD34 immunohistochemical staining. The mRNA and protein secretion of the Angs, Tie-2 and VEGF were measured by real-time polymerase chain reaction and enzyme-linked immunosorbent assays, respectively, in LNCaP (AD) and LNCaP-19, C4-2, C4-2B4 and PC-3 (AI) prostate cancer xenografts in mice. RESULTS: LNCaP, C4-2 and C4-2B4 xenografts had high expression of Ang-2 and VEGF, similar MVD and blood vessel morphology. However, the most angiogenic cell line LNCaP-19 expressed low levels of both factors and had different vessel morphology. PC-3 xenografts had a similar MVD to LNCaP, C4-2 and C4-2B4, but the Ang-2 and VEGF expression as well as the vessel morphology were similar to LNCaP-19. CONCLUSION: The differences in MVD, blood vessel morphology and the expression of Ang-2 and VEGF show that prostate cancer cells display angiogenic heterogeneity, which indicates different roles of these factors in the regulation of angiogenesis in different stages of prostate cancer.