The role of folate receptor alpha (FRalpha) in the response of malignant pleural mesothelioma to pemetrexed-containing chemotherapy.

BACKGROUND: The standard treatment of choice for malignant pleural mesothelioma is chemotherapy with pemetrexed and platinum, but the clinical outcome is poor. This study investigates the response to pemetrexed in a panel of eight mesothelioma cell lines and the clinical outcome for patients treated with pemetrexed in relation to folate receptor alpha (FRalpha). METHODS: Cell lines were treated with pemetrexed to determine the concentration that reduced growth to 50% (GI(50)). FRalpha expression was determined by western blotting and that of FRalpha, reduced folate carrier (RFC) and proton-coupled folate transporter (PCFT) by real-time quantitative RT-PCR. Immunohistochemistry for FRalpha was carried out on 62 paraffin-embedded samples of mesothelioma from patients who were subsequently treated with pemetrexed. RESULTS: A wide range of GI(50) values was obtained for the cell lines, H2452 cells being the most sensitive (GI(50) 22 nM) and RS5 cells having a GI(50) value greater than 10 microM. No FRalpha protein was detected in any cell line, and there was no relationship between sensitivity and expression of folate transporters. FRalpha was detected in 39% of tumour samples, generally in a small percentage of cells. There was no correlation between the presence of FRalpha and the outcome of pemetrexed treatment, and no significant difference between histological subtypes. CONCLUSION: Response to treatment with pemetrexed does not depend on the presence of FRalpha.

hEGR1 is induced by EGF, inhibited by gefitinib in bladder cell lines and related to EGF receptor levels in bladder tumours.

The effect of EGF and gefitinib on two EGFR-positive human bladder cancer cell lines has been investigated using array-based gene expression profiling. The most prominent transcript, increased up to 6.7-fold by EGF compared with controls in RT112 cells, was human early growth response protein 1 (hEGR1). This induction was prevented by gefitinib. The hEGR1 mRNA in EGF-treated samples was reduced in the presence of gefitinib, as was hEGR1 protein in cell lysates. In the RT4 cells, hEGR1 expression was halved in the presence of EGF and gefitinib in combination. In bladder tumour samples, there was a significant correlation between hEGR1 mRNA detected by RT-PCR and EGFR detected by ligand binding, (P=0.042). The induction by EGF of the hEGR1 gene, mRNA and protein in RT112 cells, and its inhibition by gefitinib, together with the detection of hEGR1 mRNA in bladder tumours, suggests that hEGR1 may be important in the EGFR growth-signalling pathway in bladder cancer and should be further investigated for its prognostic significance and as a potential therapeutic target.

Gefitinib ('Iressa', ZD1839) inhibits the growth response of bladder tumour cell lines to epidermal growth factor and induces TIMP2.

The effect of EGF stimulation and its inhibition with gefitinib ('Iressa', ZD1839), an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, has been investigated in two EGFR-positive human bladder tumour cell lines, RT112 and RT4. The growth of RT112 cells in a medium containing 10% foetal bovine serum was inhibited by 50% with 10 microM gefitinib, whereas this dose completely inhibited RT4 cell growth. Cells were more sensitive to growth inhibition in the serum-free medium. Increased growth of cells in the serum-free medium was observed with 10 or 50 ng x ml(-1) EGF and the proliferative effect of EGF stimulation in both cell lines was inhibited in the presence of 1 microM, but not 0.1 microM gefitinib. Zymography of the conditioned medium from RT112 cells treated with EGF and gefitinib showed a decrease in matrix metalloproteinase 2 (MMP2) concentrations. Western blot analysis showed that tissue inhibitor of metalloproteinase 1(TIMP1) increased in the conditioned medium from RT112 cells treated with EGF, and this was partially inhibited with both 1 and 5 microM gefitinib. Conversely, TIMP2 decreased with EGF stimulation and this was reversed with gefitinib. Tissue inhibitor of metalloproteinase 1 had no effect on the growth of either cell line. These studies show alterations in the balance of MMPs and their inhibitors in EGF-stimulated bladder tumour cells, which are reversed by gefitinib, suggesting gefitinib should be investigated for its effect on human bladder tumours.

Matrix metalloproteinases (MMPs) in bladder cancer: the induction of MMP9 by epidermal growth factor and its detection in urine.

OBJECTIVES: To investigate the matrix metalloproteinases (MMPs) 2 and 9 in bladder cancer cell lines stimulated with epidermal growth factor (EGF), and to investigate the presence of gelatinases in the urine of patients with bladder tumours, in relation to the stage and grade of tumour and the EGF receptor (EGFR) status. PATIENTS, SUBJECTS AND METHODS: Conditioned media from cultured tumour cells were analysed by zymography. Urine samples from 28 patients with transitional cell carcinoma and 12 normal volunteers were also analysed. Western blotting was used to verify the bands of gelatinolytic activity. The EGFR status of the tumours was assessed by immunohistochemistry. RESULTS: MMP9 was induced by EGF in the RT112 but not the RT4 bladder tumour cell line, whereas MMP2 production was unaffected by EGF. Gelatin zymography of urine samples from patients with bladder tumours showed high levels of MMP activity, with 78% positive for MMP9 and 28% positive for MMP2. The total gelatinolytic and MMP9 activity were significantly higher in patients with high-stage invasive tumours than in those with superficial tumours (P < 0.05), and were higher than in normal controls. Gelatinolytic activity at 130 and 200 kDa in urine was identified as MMP9 and MMP2. There was no significant relationship of urinary MMP9 activity to EGFR status of the tumour. CONCLUSION: EGF induces MMP9 but not MMP2 in bladder cells. Analysis of urinary gelatinases is a useful noninvasive technique and both total gelatinase and MMP9 activity are associated with high stages of bladder tumours.

Prognostic significance of matrix metalloproteinase-1 and tissue inhibitor of metalloproteinase-1 in voided urine samples from patients with transitional cell carcinoma of the bladder.

PURPOSE: To study the role of urinary matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in bladder cancer and their relationship to tumor progression. EXPERIMENTAL DESIGN: MMP-1 and TIMP-1 were measured by ELISA in urine samples from 131 patients with bladder tumors (7 cis, 74 Ta, 29 T1, and 21 T2-T4; 46 G(1), 41 G(2), and 37 G(3)), 5 patients with prostate cancer, 33 patients with benign lower urinary tract disorders, and 36 healthy volunteers. Complete clinical data were available for 100 patients with bladder cancer with a median follow-up time of 24 months (range: 4-39 months). RESULTS: MMP-1 was detected in urine samples from 21 of 131 (16%) patients with bladder cancer but was undetectable in samples from all other groups (P < 0.0001). Urinary MMP-1 was detected in a higher percentage of patients with T2-T4 tumors and G(3) tumors than patients with cis/Ta/T1 or G(1)-G(2) tumors (P = 0.04 and P = 0.0074, respectively). Patients with detectable concentrations of urinary MMP-1 had higher rates of disease progression (P = 0.04) and death from bladder cancer (P = 0.02) than patients with undetectable urinary MMP-1. All patient groups had higher urinary TIMP-1 concentrations than healthy volunteers (P = 0.02). Patients with muscle-invasive tumors had higher concentrations of urinary TIMP-1 than patients with cis/Ta/T1 tumors (P = 0.037), but there was no association between TIMP-1 and tumor grade. Urinary TIMP-1 levels strongly correlated with tumor size (P = 0.0002). Progression-free survival rates were lower for patients with urinary TIMP-1 concentrations above the median (1.8 ng/ml, P = 0.04), but urinary TIMP-1 levels were not related to disease-specific survival. Patients with T2-T4 tumors and G(3) tumors had significantly lower urinary MMP-1:TIMP-1 ratios than patients with Ta/T1 bladder tumors (P = 0.039) or G(1)-G(2) tumors (P = 0.0415). CONCLUSIONS: Where urinary MMP-1 is detectable, the patient is more likely to have a bladder tumor of advanced stage or grade and may be at increased risk of disease progression and death of bladder cancer. The relationship between urinary TIMP-1, muscle-invasion, and disease progression in bladder cancer is at variance with its role as an inhibitor of MMPs and warrants additional evaluation.

Matrix metalloproteinase-1 is induced by epidermal growth factor in human bladder tumour cell lines and is detectable in urine of patients with bladder tumours.

The matrix metalloproteinases are a family of enzymes that degrade the extracellular matrix and are considered to be important in tumour invasion and metastasis. The effect of epidermal growth factor (EGF) on matrix metalloproteinase-1 (MMP1) production in two human bladder tumour cell lines, RT112 and RT4, has been investigated. In the RT112 cell line, an increase in MMP1 mRNA levels was found after a 6-h incubation with EGF, and this further increased to 20-fold that of control levels at 24- and 48-h treatment with 50 ng ml(-1) of EGF. MMP2 mRNA levels remained constant over this time period, whereas in the RT4 cells no MMP2 transcripts were detectable, but MMP1 transcripts again increased with 24- and 48-h treatment with 50 ng ml(-1) of EGF. MMP1 protein concentration in the conditioned medium from both cell lines increased with 24- and 48-h treatment of the cells and the total MMP1 was higher in the medium than the cells, demonstrating that the bladder tumour cell lines synthesize and secrete MMP1 protein after continuous stimulation with EGF. MMP1 protein was detected in urine from patients with bladder tumours, with a significant increase in concentration with increased stage and grade of tumour. MMP1 urine concentrations may therefore be a useful prognostic indicator for bladder tumour progression.

Induction of metalloproteinase (MMP1) expression by epidermal growth factor (EGF) receptor stimulation and serum deprivation in human breast tumour cells.

The levels of the matrix metalloproteinase MMP1 mRNA in three breast tumour cell lines with varying numbers of epidermal growth factor (EGF) receptors, MDA-MB-231, T47D and MCF7, were investigated following treatment with EGF or TGF alpha in serum-free medium for up to 24 h. A higher level of MMP1 mRNA was found in both control and treated MDA-MB-231 cells compared with the other two cell lines. A 2-fold increase in MMP1 transcripts was observed in MDA-MB-231 cells following a 30 min treatment with EGF and 2 h with TGF alpha. An increase in MMP1 transcripts following serum deprivation in the absence of growth factor stimulation was also seen. This effect was not evident with the other cell lines. In MDA-MB-231 cells, low concentrations of MMP1 protein were detected in medium from treated cells and was only significantly increased after 24 h but it was inhibited by cycloheximide. The early effect of EGF on MMP1 expression was not inhibited by cycloheximide. Treatment with cycloheximide for longer periods produced increased transcripts of MMP1, TGF alpha and EGF-receptor, suggesting the activation of processes for tissue breakdown and subsequent repair may occur on prolonged inhibition of protein synthesis. These results confirm a relationship between EGF-receptor stimulation and MMP1 expression in some EGF-receptor positive tumour cells, which, in part, occurs at the transcriptional level, and have implications for the invasive progression of EGF-receptor positive tumours particularly in areas of nutritional deprivation.

Phorbol ester and bryostatin effects on growth and the expression of oestrogen responsive and TGF-beta 1 genes in breast tumour cells.

The phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA) (10 nM) produce a marked reduction in the growth, measured by thymidine uptake, of MCF-7 cells in full growth medium, but had only a small effect on MDA-MB-231 and T47D cells. Bryostatin alone also inhibited growth but to a lesser extent than seen with TPA. The effect of TPA on MCF-7 cells was partially reversed by bryostatin, added simultaneously or after TPA, suggesting bryostatin does not simply mimic TPA in this system. Even though both are believed to act via effects on protein kinase C, bryostatin appears to act as antagonist to the effect of TPA as well as a partial agonist on its own. When the oestrogen receptor positive MCF-7 and T47D cells were maintained in charcoal stripped serum, the increase in DNA synthesis on stimulation with oestradiol was inhibited with 50 nM TPA in MCF-7 cells but not in T47D cells. The effects of these treatments on the expression of two well characterised oestrogen responsive genes pNR2(pS2) and pNR100 (Cathepsin-D) were examined. Rather than preventing transcription of these oestrogen responsive genes, TPA alone increased pNR2 and pNR100 levels in MCF-7 cells and the combined effect of oestradiol and TPA had a marked synergistic effect in increasing the transcript levels of these genes. In T47D cells pNR2 transcripts were not detected and the increase in pNR100 mRNA levels were not affected by TPA. We conclude that the inhibitory effects of TPA on the growth stimulation of MCF-7 cells by oestradiol was not due to a general inhibition of the expression of oestrogen responsive genes. An alternative possibility examined was that the growth inhibitory effect of TPA on MCF-7 cells might be due to stimulation of TGF-beta 1, acting as an autocrine inhibitory growth factor. Oestradiol treatment of MCF-7 cells reduced the levels of TGF-beta 1 mRNA whereas TPA produced a marked increase. The combined effect of TPA and oestradiol further increased TGF-beta 1 mRNA above the levels seen with TPA alone. Bryostatin had little effect on TGF-beta 1 expression either alone or in combination with oestradiol. These observations are consistent with the hypothesis that the inhibitory effect of TPA on MCF-7 cells may be partly due to autocrine inhibition by TGF-beta 1.