Metformin enhances the antiproliferative and apoptotic effect of bicalutamide in prostate cancer.

BACKGROUND: Prostate cancer incidence and mortality vary dramatically by geographical location. Both are higher in developed countries. Some attribute this to westernized lifestyles of high-energy diets and limited physical activity with consequent obesity. Obesity and obesity-related diseases like diabetes cause hyperinsulinaemia, which upregulates pro-survival cell signalling. Previous work revealed diet-induced hyperinsulinaemia enhances prostate cancer xenograft growth in vivo. Metformin, an antidiabetic medication, reduces hyperinsulinaemia and also exhibits antineoplastic properties. Herein, we assess the potential additive benefit of combining bicalutamide antiandrogen therapy with metformin, in vitro and in vivo. METHODS: Using clonogenic assays, we assessed the effect of bicalutamide and/or metformin on clonogenicity in prostate cancer cell lines. Western blot and cell cycle analyses were used to elucidate mechanisms of interaction between the drugs in androgen receptor (AR)-positive (LNCaP) and AR-negative (PC3) cell lines. The combination treatment regimen was assessed in vivo using an LNCaP murine xenograft model. RESULTS: Micromolar bicalutamide or millimolar metformin caused a significant dose-dependent reduction in clonogenicity (P<0.001). Combination treatment further significantly reduced clonogenicity (P<0.005) with greater effects in AR-positive cells. Western blot and cell cycle analyses suggested differing mechanisms of interaction in AR-positive and -negative cell lines. Following combination treatment, LNCaP cells exhibited an altered cell proliferation (decreased phospho mammalian target of rapamycin expression) and perturbed cell cycle kinetics (G1/S cell cycle arrest). PC3 cells showed evidence of enhanced apoptosis (increased Bcl-2-associated X protein and decreased total caspase 3 expression). Markedly diminished tumour growth occurred following combination treatment in vivo (P<0.001). CONCLUSIONS: Combining bicalutamide and metformin significantly reduces prostate cancer cell growth further than either monotherapy. In AR-positive cells, this effect appeared to be mediated by reducing proliferation rates, whereas in AR-negative cells the combination treatment appeared to promote apoptosis. This combination drug regimen may improve prostate-cancer-specific survival by the direct antineoplastic properties outlined.

Carbonic anhydrase IX expression and outcome after radiotherapy for muscle-invasive bladder cancer.

AIMS: Carbonic anhydrase IX (CA IX) expression has been described as an endogenous marker of hypoxia in solid neoplasms. Furthermore, CA IX expression has been associated with an aggressive phenotype and resistance to radiotherapy. We assessed the prognostic significance of CA IX expression in patients with muscle-invasive bladder cancer treated with radiotherapy. MATERIALS AND METHODS: A standard immunohistochemistry technique was used to show CA IX expression in 110 muscle-invasive bladder tumours treated with radiotherapy. Clinicopathological data were obtained from medical case notes. RESULTS: CA IX immunostaining was detected in 89 ( approximately 81%) patients. Staining was predominantly membranous, with areas of concurrent cytoplasmic and nuclear staining and was abundant in luminal and perinecrotic areas. No significant correlation was shown between the overall CA IX status and the initial response to radiotherapy, 5-year bladder cancer-specific survival or the time to local recurrence. CONCLUSIONS: The distribution of CA IX expression in paraffin-embedded tissue sections seen in this series is consistent with previous studies in bladder cancer, but does not provide significant prognostic information with respect to the response to radiotherapy at 3 months and disease-specific survival after radical radiotherapy.

Combination treatment with ionising radiation and gefitinib ('Iressa', ZD1839), an epidermal growth factor receptor (EGFR) inhibitor, significantly inhibits bladder cancer cell growth in vitro and in vivo.

PURPOSE: External beam radiotherapy (EBRT) is the principal bladder-preserving monotherapy for muscle-invasive bladder cancer. Seventy percent of muscle-invasive bladder cancers express epidermal growth factor receptor (EGFR), which is associated with poor prognosis. Ionising radiation (IR) stimulates EGFR causing activation of cytoprotective signalling cascades and thus may be an underlying cause of radioresistance in bladder tumours. MATERIALS AND METHODS: We assessed the ability of IR to activate EGFR in bladder cancer cells and the effect of the anti-EGFR therapy, gefitinib on potential radiation-induced activation. Subsequently we assessed the effect of IR on signalling pathways downstream of EGFR. Finally we assessed the activity of gefitinib as a monotherapy, and in combination with IR, using clonogenic assay in vitro, and a murine model in vivo. RESULTS: IR activated EGFR and gefitinib partially inhibited this activation. Radiation-induced activation of EGFR activated the MAPK and Akt pathways. Gefitinib partially inhibited activation of the MAPK pathway but not the Akt pathway. Treatment with combined gefitinib and IR significantly inhibited bladder cancer cell colony formation more than treatment with gefitinib alone (p = 0.001-0.03). J82 xenograft tumours treated with combined gefitinib and IR showed significantly greater growth inhibition than tumours treated with IR alone (p = 0.04). CONCLUSIONS: Combining gefitinib and IR results in significantly greater inhibition of invasive bladder cancer cell colony formation in vitro and significantly greater tumour growth inhibition in vivo. Given the high frequency of EGFR expression by bladder tumours and the low toxicity of gefitinib there is justification to translate this work into a clinical trial.

Epidermal growth factor receptor status predicts local response to radical radiotherapy in muscle-invasive bladder cancer.

AIMS: Epidermal growth factor receptor (EGFR) is expressed by over 70% of muscle-invasive bladder tumours and is associated with diminished overall survival. In model tumour systems, ionising radiation has been shown to activate EGFR, leading to cellular proliferation and is therefore a possible mechanism of underlying radioresistance. We carried out an immunohistochemical study relating the clinical outcome of patients receiving radical radiotherapy for muscle-invasive bladder cancer to tumour EGFR status. MATERIALS AND METHODS: Archived paraffin-embedded tumours from 110 consecutive patients receiving radical radiotherapy for muscle-invasive bladder cancer between 1991 and 1997 were immunohistochemically stained for EGFR. Data were collected concerning the tumour stage and grade, the presence of ureteric obstruction, the response to radiotherapy at 3 months, local recurrence rates, metastatic spread and survival. Multivariate analysis of potential independent prognostic factors of impaired bladder cancer-specific survival was carried out using Cox's regression. RESULTS: Of 110 tumours, 79 (72%) stained positively for EGFR. Of 87 patients undergoing the 3-month check cystoscopy, 60 (69%) had a positive response to radiotherapy. A positive response to radiotherapy correlated significantly with a negative EGFR status (chi(2) test, P = 0.05). Kaplan-Meier survival analysis revealed a trend towards improved bladder cancer-specific survival in EGFR-negative patients (Log-rank, P = 0.10). A lack of response to radiotherapy at 3 months, local recurrence, metastatic spread and the presence of ureteric obstruction were all independent prognostic factors for diminished bladder cancer-specific survival (Cox's regression: P = 0.009, P = 0.001, P = 0.04 and P = 0.005, respectively). CONCLUSIONS: EGFR status predicts the local response to radiotherapy but does not provide prognostic utility in relation to overall or bladder cancer-specific survival. As EGFR status seems to be linked to the initial response to radiotherapy, its inhibition may be a means of enhancing the radio-responsiveness of these poor prognosis tumours. Colquhoun, A. J.

Epidermal growth factor receptor and bladder cancer.

Muscle-invasive bladder cancer is a disease which causes significant morbidity and mortality. The two main forms of treatment for this disease include radical cystectomy and radical radiotherapy, but five year survival after treatment remains low at 40%. Many clinical and molecular risk factors have been shown to be associated with poor prognosis. One such factor is the expression of epidermal growth factor receptor (EGFR), which is overexpressed by many epithelial tumours, including bladder cancers. There are several methods of inhibiting the activity of EGFR and it may be that use of an anti-EGFR therapy, in combination with more conventional treatment, provides a method of improving the prognosis for muscle-invasive bladder cancer.

Effectiveness of influenza vaccine in reducing hospital admissions in people with diabetes.

The effectiveness of influenza vaccination in reducing hospitalization of people with diabetes for influenza, pneumonia, or diabetic events during influenza epidemics was assessed in a case control study in Leicestershire, England. Cases were 80 patients on the Leicestershire Diabetes Register who were admitted and discharged from hospital with International Classification of Disease codes for pneumonia, bronchitis, influenza, diabetic ketoacidosis, coma and diabetes, without mention of complications, during the influenza epidemics of 1989-90 and 1993. One hundred and sixty-controls, who were not admitted to hospital during this period, were randomly selected from the Register. Immunization against influenza was assessed in 37 cases and 77 controls for whom consent was obtained to access their clinical notes and for whom notes were available. Significant association was detected between reduction in hospitalization and influenza vaccination during the period immediately preceding an epidemic. Multiple logistic regression analysis estimated that influenza vaccination reduced hospital admissions by 79% (95% CI 19-95%) during the two epidemics, after adjustment for potential confounders.

Uptake of 2-[(14)C]abscisic acid by senescing leaf tissue of radish, Raphanus sativus L.

The uptake of [(14)C]abscisic acid by radish leaf discs rises one to two days after excision and then declines to six days. This pattern of uptake is not identical to the uptake of [(14)C]sucrose. The uptake of both [(14)C]abscisic acid and [(14)C]sucrose is substantially reduced by anaerobic conditions.

The effects of abscisic acid on senescence in leaf discs of radish, Raphanus sativus L.

After a 6 day incubation period, abscisic acid (ABA) at 10(-4) M retarded the decline in pigment levels and promoted the decline in protein levels of radish leaf discs. ABA treatment also retarded the rise in the specific activity of the RNA fraction (calculated by counts per minute incorporated of (14)C-8-adenine as a fraction of optical density at 260 nm) observed in water-treated control discs. The results indicated that ABA was primarily effective in enhancing senescence in the early stages following leaf excision. Thus the increase in RNA specific activity during an initial 24 h incubation period was especially pronounced with ABA treatment although there was no effect of the hormone on RNA level. Moreover, in contrast to control discs, the pigment levels declined markedly in ABA-treated discs in this period. When the discs had been incubated in water ("preaged") for 3 or 5 days prior to ABA treatment, however, the hormone then had little effect on RNA metabolism and protein and pigment levels relative to the water control.Data are collated from different experiments to show the changes in RNA, pigment and protein with ABA treatment during a 6 day senescence period.It is considered that ABA is speeding up the natural changes in RNA metabolism possibly by affecting both RNA synthesis and degradation.