Abnormal signalling events mediated by receptor tyrosine kinases (RTKs) contribute to human carcinogenesis. Sprouty2 (Spry2) is a key antagonistic regulator of RTK signalling and suppression of its expression or function may facilitate proliferation and angiogenesis. Using prostate cancer (CaP) as a model, we investigated the significance of Spry2 in human malignancy. We observed downregulated Spry2 expression in invasive CaP cell lines and high-grade clinical CaP (compared to benign prostatic hyperplasia (BPH) and well-differentiated tumours, P ¼ 0.041). A large CpG island is associated with hSPRY2, and extensive hypermethylation of this CpG island was observed in 76-82% of high-grade CaP, while control BPH tissues were predominantly unmethylated (P ¼ 0.0005). Furthermore, suppressed Spry2 expression correlated with methylation of the CpG region in clinical samples (P ¼ 0.004) and treatment with 5-aza-2 0 -deoxycytidine reactivated Spry2 expression in LNCaP and PC-3M cells. hSPRY2 maps to the long arm of chromosome 13 (13q31.1), where loss of heterozygosity (LOH) has been reported. We found no evidence of mutation; however, we demonstrated 27-40% LOH using flanking markers to hSPRY2. Hence, while biallelic epigenetic inactivation of hSPRY2 represents the main genetic event in prostate carcinogenesis, the observed 27-40% LOH presents evidence of hemizygous deletion with the remaining allele hypermethylated. We therefore propose hSPRY2 as a potential tumour suppressor locus in CaP.
Overexpression of fibroblast growth factors (FGFs) has been implicated in prostate carcinogenesis. FGFs function via their high-affinity interactions with receptor tyrosine kinases, FGFR1 -4. Expression of FGFR1 and FGFR2 in prostate cancer (CaP) was not found to be associated with clinical parameters. In this report, we further investigated for abnormal FGFR expression in prostate cancer and explore their significance as a potential target for therapy. The expression levels of FGFR3 and FGFR4 in CaP were examined and corroborated to clinical parameters. FGFR3 immunoreactivity in benign prostatic hyperplasia (BPH) and CaP (n ¼ 26 and 57, respectively) had similar intensity and pattern. Overall, FGFR4 expression was significantly upregulated in CaP when compared to BPH. A significant positive correlation between FGFR4 expression and Gleason score was noted: Gleason score 7 -10 tumours compared to BPH (Po0.0001, Fisher's exact test), Gleason score 4 -6 tumours compared to BPH (Po0.0004), and Gleason 7 -10 compared to Gleason 4 -6 tumours (Po0.005). FGFR4 overexpression was associated with an unfavourable outcome with decreased disease-specific survival (Po0.04, log rank test). FGF-induced signalling is targeted using soluble FGF receptor (sFGFR), potent inhibitor of FGFR function. We have previously shown that sFGFR expression via a replication-deficient adenoviral vector (AdlllcRl) suppresses in vitro FGF-induced signalling and function in human CaP DU145 cells. We tested the significance of inhibiting FGF function along with conventional therapeutic modalities in CaP, and confirmed synergistic effects on in vitro cell growth (proliferation and colony formation) by combining sFGFR expression and treatment with either Paclitaxel (Taxol s ) or g-irradiation. In summary, our data support the model of FGF system as valid target for therapy in CaP. Prostate cancer is the commonest cancer in men and the second commonest cause of cancer-related death in men, and its incidence is increasing (Woolf, 1995;Boyle et al, 1996). Prostate cancer is an enigmatic disease. It is histologically present in 80% of men over the age of 80 years, but will only clinically manifest itself in about 10%. Increasing use of serum measurement of prostate-specific antigen is facilitating early diagnosis of prostate cancer. There are currently limited prognostic markers that may allow patients found to have early prostate cancer to be stratified into different management plans. Hence, new methods of predicting disease progression are urgently needed.Abnormal expression of peptide growth factors and their highaffinity receptor tyrosine kinases are important in the development and progression of prostate cancer. These mitogens enhance tumour proliferation and invasion while inhibiting apoptosis. Several peptide growth factors have been implicated in prostate cancer development and progression, including insulin-like growth factors, epidermal growth factor and members of the fibroblast growth factors (Byrne et al, 1996;Tennant et al, 1996;Dorkin et...
Over-expression of fibroblast growth factor 8 (FGF8) in human prostate cancer is associated with clinically aggressive disease. Among different members of the FGF family, FGF17 and FGF8 share high sequence homology and have similar patterns of expression during embryogenesis. In this study, the clinical significance of FGF17 expression and its in vitro function in prostate cancer cells were tested. Forty resected prostate specimens from patients with benign prostatic hyperplasia (BPH, n = 12) and prostate cancer (CaP, n = 28; Gleason sum scores 3-10) were studied using semi-quantitative RT-PCR. In addition, 85 cases of CaP (Gleason sum scores 5-9) and 20 cases of BPH were examined using immunohistochemistry and findings were correlated with clinical parameters. In vitro experiments using prostate cancer cell lines examined the functional significance of FGF17 in prostate cancer. These studies revealed a significant linear correlation between increasing Gleason sum scores and FGF17 expression using both immunohistochemistry (p < 0.0001, rho = 0.99) and RT-PCR (p = 0.008, rho = 0.99). Immunohistochemistry demonstrated upregulation of FGF17 in CaP compared with BPH (p < 0.0001) and, when comparing high-grade CaP (Gleason sum score 7-10) with BPH, RT-PCR showed a fourfold upregulation of FGF17 mRNA expression (p < 0.0001). Men with tumours displaying high levels of FGF17 expression had a worse outcome on survival analysis (p = 0.044) and a higher risk of progression with metastases (p < 0.0001). Proliferation assays showed low-dose recombinant (r) FGF17 (1 ng/ml) to be a more potent mitogen than rFGF1 and rFGF8 in prostate cancer cell lines (LNCaP, DU145, and PC3M) (p < 0.001). Furthermore, FGF8 was shown to induce expression of FGF17 in these cell lines. These data support a role for FGF17, and a model of co-expression of multiple FGFs, with FGF17 as a potential mediator of FGF8 function, in human prostate carcinogenesis.
Prostate cancer is the most common cancer amongst men in the USA and the second most common malignant cause of male death worldwide after lung cancer. The life time risk of having microscopic evidence of prostate cancer for a 50 year old man is 42%. Prostate cancer is thus becoming an increasingly significant global health problem in terms of mortality, morbidity, as well as economically. This review, discusses current medical therapeutic options for prostate cancer including traditional treatments using luteinising hormone releasing analogues (LHRH), anti-androgens and estrogen treatments, and the use of novel drugs directed against molecular targets considered important in oncogenesis and metastasis. Prostate cancer chemoprevention using 5alpha-reductase inhibitors and the role of gene therapy are also considered.
BACKGROUND:Meta-analysis data demonstrate a 5% absolute survival benefit for neoadjuvant chemotherapy (NAC) using cisplatinbased combination regimens in the radical treatment of muscle-invasive bladder cancer (MIBC). However, there are no randomized, controlled trial data on the optimum regimen. Accelerated methotrexate, vinblastine, doxorubicin, and cisplatin (AMVAC) is a doseintense regimen that has the potential to minimize delays to definitive, potentially curative therapy. A retrospective analysis is presented of the efficacy and toxicity of AMVAC as NAC in patients with MIBC and its impact on the patient pathway. METHODS: Eighty consecutive patients with MIBC were treated with AMVAC as NAC by 2 UK multidisciplinary uro-oncology teams. Three or 4 cycles of AMVAC (methotrexate 30 mg/m 2 , vinblastine 3 mg/m 2 , doxorubicin 30 mg/m 2 , and cisplatin 70 mg/m 2 ) were given at 2-week intervals, with granulocyte colony-stimulating factor support, prior to either radical surgery or radical radiotherapy. RESULTS: All planned cycles of chemotherapy were completed, without dose reduction or delay in 84% of patients. All 80 patients subsequently received their planned definitive therapy. Grade 3/4 toxicities were seen in 26% of the 42% of patients for whom toxicity data are available, including 12% grade 3/4 neutropenia. Pathological complete response to AMVAC was seen in 43% of 60 surgical patients. Objective radiological local response was seen in 83% of 57 evaluable patients. Two-year disease-free and overall survival were 65% and 77%, respectively. CONCLUSIONS: AMVAC is safe and appears to be a well-tolerated and effective NAC regimen for MIBC. It minimizes delays to definitive treatment and produces excellent pathological and radiological response rates. It is an appropriate comparator for future randomized trials. Cancer 2012;118:3920-7.
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