[Chemotherapy of hormonorefractory and hormonoresistant metastatic prostate cancer]

Tumor-suppressive microRNA-218 inhibits cancer cell migration and invasion via targeting of LASP1 in prostate cancer

Our recent studies of the microRNA (miRNA) expression signature in prostate cancer (PCa) indicated that miRNA-218 (miR-218) was significantly downregulated in clinical specimens, suggesting that miR-218 might act as a tumor-suppressive miRNA in PCa. The aim of the present study was to investigate the functional significance of miR-218 in PCa and to identify novel miR-218-regulated cancer pathways and target genes involved in PCa oncogenesis and metastasis. Restoration of miR-218 in PCa cell lines (PC3 and DU145) revealed that this miRNA significantly inhibited cancer cell migration and invasion. Gene expression data and in silico analysis demonstrated that LIM and SH3 protein 1 (LASP1) is a potential target of miR-218 regulation. LASP1 is a cytoskeletal scaffold protein that plays critical roles in cytoskeletal organization and cell migration. Luciferase reporter assays showed that miR-218 directly regulated expression of LASP1. Moreover, downregulating the LASP1 gene significantly inhibited cell migration and invasion in cancer cells, and the expression of LASP1 was upregulated in cancer tissues. We conclude that loss of tumor-suppressive miR-218 enhanced cancer cell migration and invasion in PCa through direct regulation of LASP1. Our data on pathways regulated by tumor-suppressive miR-218 provide new insight into the potential mechanisms of PCa oncogenesis and metastasis.

Tumor-suppressive microRNA-29s inhibit cancer cell migration and invasion via targeting LAMC1 in prostate cancer

Our recent studies of microRNA (miRNA) expression signatures revealed that microRNA-29s (miR-29s; including miR-29a/b/c) were significantly downregulated in prostate cancer (PCa) and was a putative tumor-suppressive miRNA family in PCa. Herein, we aimed to investigate the functional significance of miR-29 in cancer cells and to identify novel miR-29s-mediated cancer pathways and target genes involved in PCa oncogenesis and metastasis. Restoration of miR-29s in PC3 and DU145 cell lines revealed significant inhibition of cancer cell migration and invasion. To identify miR-29s-mediated molecular pathways and targets, we used gene expression data and in silico database analysis. Our analysis demonstrated that miR-29s modulated the focal adhesion pathway. Moreover, the laminin γ1 (LAMC1) gene was a candidate target of miR-29s regulation. Luciferase reporter assays showed that miR-29s directly regulated LAMC1. Silencing of LAMC1 significantly inhibited cell migration and invasion in cancer cells, and LAMC1 was upregulated in PCa. miR-29s acted as tumor suppressors, contributing to cancer cell migration and invasion and directly targeting laminin signaling. Recognition of tumor-suppressive miRNA-mediated cancer pathways provides new insights into the potential mechanisms of PCa oncogenesis and metastasis, and suggests novel therapeutic strategies for treating this disease.

The tumor-suppressive microRNA-143/145 cluster inhibits cell migration and invasion by targeting GOLM1 in prostate cancer

Our recent study of microRNA (miRNA) expression signature of prostate cancer (PCa) has revealed that the microRNA-143/145 (miR-143/145) cluster is significantly downregulated in cancer tissues, suggesting that these cluster miRNAs are candidate tumor suppressors. The aim of this study was to investigate the functional significance of the miR-143/145 cluster in PCa cells and to identify novel targets regulated by these cluster miRNAs in PCa. Restoration of miR-143 or miR-145 in PCa cell lines (PC3 and DU145) revealed that these miRNAs significantly inhibited cancer cell migration and invasion. Gene expression data and in silico analysis demonstrated that Golgi membrane protein 1 (GOLM1) resembling a type II golgi transmembrane protein was a potential target of miR-143/145 cluster target gene. Gene expression studies and luciferase reporter assays showed that GOLM1 was directly regulated by the miR-143/145 cluster. Silencing of GOLM1 resulted in significant inhibition of cell migration and invasion in PCa cells. Furthermore, the expression of GOLM1 was upregulated in cancer tissues by immunohistochemistry. Loss of the tumor-suppressive miR-143/145 cluster enhanced cancer cell migration and invasion in PCa through directly regulating GOLM1. Our data on target genes regulated by the tumor-suppressive miR-143/145 cluster provide new insights into the potential mechanisms of PCa oncogenesis and metastasis.

Tumour suppressors miR-1 and miR-133a target the oncogenic function of purine nucleoside phosphorylase (PNP) in prostate cancer

Background:

Our recent analyses of miRNA expression signatures showed that miR-1 and miR-133a were significantly reduced in several types of cancer. Interestingly, miR-1 and miR-133a are located on the same chromosomal locus in the human genome. We examined the functional significance of miR-1 and miR-133a in prostate cancer (PCa) cells and identified the novel molecular targets regulated by both miR-1 and miR-133a.

Methods and Results:

The expression levels of miR-1 and miR-133a were significantly downregulated in PCa compared with non-PCa tissues. Restoration of miR-1 or miR-133a in PC3 and DU145 cells revealed significant inhibition of proliferation, migration, and invasion. Molecular target identification by genome-wide gene expression analysis and luciferase reporter assay showed that purine nucleoside phosphorylase (PNP) was directly regulated by both miRNAs. Silencing of the PNP gene inhibited proliferation, migration, and invasion in both PC3 and DU145 cells. Immunohistochemistry detected positive staining of PNP in PCa specimens.

Conclusions:

Downregulation of miR-1 and miR-133a was a frequent event in PCa and both function as tumour suppressors. The PNP is a novel target gene of both miRNAs and potentially functions as an oncogene. Therefore, identification of novel molecular networks regulated by miRNAs may provide new insights into the underlying causes of PCa oncogenesis.

Poor survival outcome of docetaxel every three weeks plus prednisone for treatment of patients with hormone-refractory metastatic prostate cancer

BACKGROUND AND OBJECTIVES

Since previous studies have indicated there are improvements in overall survival, the aim of this phase II clinical study was to evaluate docetaxel every three weeks plus prednisone as first-line chemotherapy for treatment of hormone-refractory metastatic prostate cancer (HRMPC).

METHODS

Thirty-five metastatic HRPC patients were treated with docetaxel 70 mg/m2 every 3 weeks plus oral prednisolone 5 mg twice daily at the clinical oncology departments of Tanta, Mansoura and Menofia university hospitals during the period from June 2006 to December 2008. The primary endpoint was assessment of the overall tumor response rate. Secondary endpoints were assessment of PSA response rate, overall survival rate, and the time-to-disease progression.

RESULTS

The median number of cycles administered was 6 cycles. Partial response was observed in 15 patients (42.9%) with evaluable measurable disease. Median survival from protocol entry was 15 months. Median time- to-disease progression was 10 months. Prostate-specific antigen (PSA) declined ≥50% in 9 patients (25.7%). The most common grade 3/4 toxicity associated with studied protocol was neutropenia (85.7%).

CONCLUSIONS

When given with prednisone, treatment with docetaxel every three weeks does not improve survival, so the benefit of docetaxel-based therapy is not clear this high risk and poor prognostic group of patients.

[The French clinical trials ongoing (GETUG and AFU) on urothelial carcinomas, kidney and prostate cancers]

The collaboration of the Association Française d'Urologie (AFU) and of the Groupe d'Etude des Tumeurs Uro-Genital (GETUG) has lead to increase more and more the credibility of French clinical trials in onco-urology. These trials are on the same level ast North American or European studies. The involvement of urologists is essential. Therefore it seemed necessary to do an update on ongoing trials to further increase recruitment from all practitioners involved in onco-urology.

[Chemotherapy in early stage of hormone-resistant metastatic prostate cancer: what are the indications?]

Treatment of hormone-refractory prostate cancer remains a source of debate. Since 2004, docétaxel-based chemotherapy has become the standard treatment as it has demonstrated efficacy on overall survival in two randomized studies. In some studies, chemotherapy seems to be also effective on pain relief. The adverse effects occur more frequently than with others chemotherapy (mitoxantrone) but are moderated and aren't responsible of specific mortality. These facts encourage to begin the chemotherapy as earlier as possible even before metastases appear. Some studies have even raised the issue of an initiation of chemotherapy before the onset of hormone independence. However these arguments might be use with caution. The treated patients have a limited life expectancy and a 2 months gain of survival may be of limited value. Furthermore, even low side effects can generate a morbidity on these fragile patients especially when they are initially asymptomatic. Thus, an early initiation of chemotherapy must be discussed case by case, on an individual basis. The prognosis factors and alternative therapeutic options based on new molecules used in metastatic cancer might also be considered for the therapeutic decision.