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Biomedical subjects

Joanne Edwards

Publications and source records attributed to Joanne Edwards.

11 recordsLinked to original sources
PubMed2006

The role of HER1-HER4 and EGFRvIII in hormone-refractory prostate cancer.

PURPOSE: The role of the type I receptor tyrosine kinase (HER) family in progression of prostate cancer is controversial. Breast cancer studies show that these receptors should be investigated as a family. The current study investigates expression of HER1-HER4 and EGFRvIII in matched hormone-sensitive and hormone-refractory prostate tumors. EXPERIMENTAL DESIGN: Immunohistochemical analysis was used to investigate protein expression of HER1-HER4, EGFRvIII, and phosphorylated Akt (pAkt) in matched hormone-sensitive and hormone-refractory prostate tumors. RESULTS: Surprisingly, high HER2 membrane expression in hormone-sensitive tumors was associated with an increased time to biochemical relapse (P = 0.0003), and this translated into longer overall survival (P = 0.0021). Consistent with other studies, HER4 membrane expression in hormone-sensitive tumors was associated with longer time to biochemical relapse (P = 0.042), and EGFRvIII membrane expression was associated with shorter time to biochemical relapse (P = 0.015). An increase in pAkt expression was associated with reduced survival (P = 0.0098). Multivariate analysis showed that HER2 was an independent positive predictive marker of time to relapse in hormone-sensitive prostate tumors (P = 0.014). In contrast, high HER2 expression in hormone-refractory tumors was associated with decreased time to death from biochemical relapse (P = 0.039), and EGFRvIII nuclear expression was associated with decreased time to death from biochemical relapse and decreased overall survival (P = 0.02 and P = 0.005). CONCLUSION: These results suggest that the HER family may have multiple roles in prostate cancer, and that expression of the proteins alone is insufficient to predict the biological response that they may elicit.

Biomarkers, Tumor↗
PubMed2005

Type I receptor tyrosine kinases are associated with hormone escape in prostate cancer.

Relapse during androgen withdrawal therapy is a significant cause of morbidity and mortality from prostate cancer. Androgen receptor mutations (6-10%) and amplifications (20-30%) may explain relapse in some patients, but in approximately 70% of cases, alternative mechanisms must be invoked and preliminary evidence suggests that type I receptor tyrosine kinases play a role in mediating hormone escape. In this study, EGFR and HER2 gene amplification and expression were analysed by fluorescence in situ hybridization and immunohistochemistry, respectively, in a cohort of matched tumour pairs (one taken before and one after hormone relapse) from 49 prostate cancer patients. No EGFR amplification and low-level, heterogeneous HER2 amplification were observed (6.5%). No significant correlation between EGFR/HER2 gene copy and protein expression was found. Almost one quarter of the cases (12/49, 24.5%) showed increased HER2 or EGFR expression at hormone relapse; this was associated with a significant reduction in time from hormone relapse to death (p = 0.0003). EGFR and HER2 amplification do not play a significant role in prostate cancer, but increased expression of HER2 or EGFR may influence progression to androgen independence in about a quarter of cases as a rise in EGFR/HER2 expression at hormone relapse is associated with a significant reduction in time to death. These findings support the development of EGFR/HER2 targeted therapies in androgen-independent prostate cancer and demonstrate, using a carefully characterized patient cohort, that the EGFR/HER2 pathway may represent one of a number of independent routes to hormone escape in prostate cancer.

Androgens↗
PubMed2005

The relationship between angiogenesis and cyclooxygenase-2 expression in prostate cancer.

OBJECTIVE: To test the hypothesis that angiogenesis in prostate cancer is associated with tumour invasion and metastasis, and that this is mediated through increased cyclooxygenase-2 (COX-2) expression. PATIENTS AND METHODS: Angiogenesis was assessed in 105 patients with either prostate cancer (79) or benign prostatic hyperplasia (BPH, 26) and these data correlated with levels of COX-2 expression in the same dataset. The mean microvessel density (MVD) was analysed as a marker of angiogenesis, using the endothelial antigen CD34 stained by immunohistochemistry. RESULTS: There was no difference in MVD in progressive tumour stages compared with BPH. There was a negative correlation between MVD and COX-2 expression, but the effect of increased COX-2 expression on MVD was not marked. CONCLUSION: These data suggest that COX-2 drives tumour spread in prostate cancer by means other than the promotion of angiogenesis.

Aged↗
PubMed2004

The role of c-Jun and c-Fos expression in androgen-independent prostate cancer.

Molecular mechanisms underlying the development of androgen-insensitive prostate cancer (AIPC) are poorly understood. However, there is growing evidence that different molecular profiles may result in the development of AIPC. Cell line studies demonstrate that c-Jun and c-Fos, via formation of the transcription factor activated protein 1 (AP-1), activate androgen-regulated genes independent of androgens and that c-Jun alone acts as an androgen receptor co-factor. The aim of this study was to investigate whether increased levels of c-Jun and phosphorylated c-Jun are associated with the development of AIPC using clinical material. Material from a cohort of 51 patients with paired tumours, obtained before and after the development of AIPC, and with full clinical biochemical follow-up, was retrieved from the archives. Tumour c-Jun, activated c-Jun, c-Fos, and pan protein kinase C (PKC) protein expression were analysed by immunohistochemistry and protein expression was scored by two independent observers using a weighted histoscore. No evidence was found to suggest that c-Jun acting as an androgen receptor co-factor influences the development of AIPC. However, it was observed that patients with high expression levels of phosphorylated c-Jun had a significantly shorter survival from relapse compared with patients with low phosphorylated c-Jun protein expression (p = 0.023), suggesting that increased AP-1 levels may promote AIPC tumour growth. Whilst PKC did not appear to activate c-Jun in vivo, increased PKC expression in AIPC tumours was also associated with decreased patient survival from time of relapse (p = 0.014). In conclusion, the data support the hypothesis that activation of c-Jun plays a role in the development of AIPC via AP-1 formation in some patients. However, PKC appears to promote the development of AIPC independently of c-Jun activation via an as yet unexplained mechanism.

Aged↗
PubMed2003

Gene amplifications associated with the development of hormone-resistant prostate cancer.

PURPOSE: Hormone resistance remains a significant clinical problem in prostate cancer with few therapeutic options. Research into mechanisms of hormone resistance is essential. EXPERIMENTAL DESIGN: We analyzed 38 paired (prehormone/posthormone resistance) prostate cancer samples using the Vysis GenoSensor. Archival microdissected tumor DNA was extracted, amplified, labeled, and hybridized to Amplionc I DNA microarrays containing 57 oncogenes. RESULTS: Genetic instability increased during progression from hormone-sensitive to hormone-resistant cancer (P = 0.008). Amplification frequencies of 15 genes (TERC, MYBL3, HRAS, PI3KCA, JUNB, LAMC2, RAF1, MYC, GARP, SAS, FGFR1, PGY1, MYCL1, MYB, FGR) increased by >10% during hormone escape. Receptor tyrosine kinases were amplified in 73% of cases; this was unrelated to development of hormone resistance. However, downstream receptor tyrosine kinase signaling pathways showed increased amplification rates in resistant tumors for the mitogen-activated protein kinase (FGR/Src-2, HRAS, and RAF1; P = 0.005) and phosphatidylinositol 3'-kinase pathways (FGR/Src-2, PI3K, and Akt; P = 0.046). Transcription factors regulated by these pathways were also more frequently amplified after escape (MYC family: 21% before versus 63% after, P = 0.027; MYB family: 26% before versus 53% after, P = 0.18). CONCLUSIONS: Development of clinical hormone escape is linked to phosphatidylinositol 3'-kinase and mitogen-activated protein kinase pathways. These pathways may function independently of the androgen receptor or via androgen receptor activation by phosphorylation, providing novel therapeutic targets.

Aged↗
PubMed2002

Identification of loci associated with putative recurrence genes in transitional cell carcinoma of the urinary bladder.

Following an earlier study linking monosomy 9 with recurrence of transitional cell carcinomas (TCCs) of the urinary bladder, 109 primary and recurrent TCCs (from 47 patients) were examined to explore genetic alterations at chromosome 9 associated with recurrence. Patient DNA was microdissected and extracted from archival tissue sections and analysed for loss of heterozygosity (LOH) at three regions on chromosome 9 where tumour suppressor genes (TSGs) are known to reside (INK 4A, DBC1, and TSC1). Patients were categorized into two groups, non-recurrent TCC (NR, n=18) and recurrent TCC (REC, n=29). It was noted that 12% of NR tumours, compared with 54% of REC primary tumours (p=0.01), had LOH at all informative markers spanning the TSC1 region. The risk of recurrence was significantly higher in patients with deleted TSC1 than in those who retained the TSC1 region (p=0.035). Levels of LOH at DBC1 or INK 4A were not significantly different in NR tumours than in REC primary tumours and recurrence-free survival was not affected by loss of either of these genes. Loss of all informative markers spanning chromosome 9 was observed in 0% of NR tumours compared with 25% of REC primary tumours (p=0.04). The probability of recurrence was also significantly increased in patients who had LOH at all informative markers spanning chromosome 9 (p=0.016), confirming earlier fluorescence in situ hybridization results. This study provides further evidence that recurrence in bladder cancer is a distinct event, with underlying molecular causes. It also identifies the TSC1 locus as a candidate for a TSG, which drives recurrence in a proportion of TCC patients. Loss of all informative markers, including those residing in the TSC1 region, spanning chromosome 9 was also linked to recurrence.

Carcinoma, Transitional Cell↗