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Biomedical subjects

Simon F Brewster

Publications and source records attributed to Simon F Brewster.

5 recordsLinked to original sources
PubMed2005

Silencing of the IGF1R gene enhances sensitivity to DNA-damaging agents in both PTEN wild-type and mutant human prostate cancer.

The type 1 insulin-like growth factor receptor (IGF1R) is overexpressed in prostate cancer, and mediates proliferation, motility, and survival. Many prostate cancers harbor inactivating PTEN mutations, enhancing Akt phosphorylation. This activates the principal antiapoptotic pathway downstream of the IGF1R, calling into question the value of IGF1R targeting in this tumor. The aim of the current study was to assess the effect of IGF1R gene silencing in prostate cancer cells that lack functional PTEN protein. In human DU145, LNCaP and PC3 prostate cancer cells, transfection with IGF1R small interfering RNA induced significant enhancement of apoptosis and inhibition of survival, not only in PTEN wild-type DU145 but also in PTEN mutant LNCaP and PC3. This was attributed to attenuation of IGF signaling via Akt, ERKs and p38. In both DU145 and PC3, IGF1R knockdown led to enhancement of sensitivity to mitoxantrone, etoposide, nitrogen mustard and ionizing radiation. There was no sensitization to paclitaxel or 5-fluorouracil, which do not damage DNA, suggesting that chemosensitization results from impairment of the DNA damage response, in addition to removal of apoptosis protection. These results support the concept of IGF1R targeting in prostate cancer, and indicate that PTEN loss does not render tumor cells refractory to this strategy.

Antineoplastic Agents↗
PubMed2005

A double-blind, randomized, controlled trial of topical glyceryl trinitrate for transrectal ultrasound guided prostate biopsy.

PURPOSE: We evaluated the efficacy and tolerance of topical 0.2% glyceryl trinitrate (GTN) paste vs placebo to decrease pain associated with transrectal ultrasound guided prostate biopsy. MATERIALS AND METHODS: Between October 2003 and April 2004, 134 consecutive patients referred for a first prostate biopsy were randomized to receive topical 0.2% GTN paste or placebo 30 minutes prior to biopsy. Participants completed a 10 point visual analog pain score following the procedure. RESULTS: Mean patient age was 68.5 years in the GTN group and 68.8 in the placebo group. There was a significant decrease in mean pain score in the GTN group compared with placebo (3.7 vs 4.8, p <0.05). Six patients (10%) in the GTN group complained of headache. CONCLUSIONS: Topical GTN paste is an effective and well tolerated method of decreasing pain associated with transrectal ultrasound guided prostate biopsy. It is safe and easy to use, and it should be offered to patients undergoing this procedure.

Administration, Topical↗
PubMed2002

Expression of the type 1 insulin-like growth factor receptor is up-regulated in primary prostate cancer and commonly persists in metastatic disease.

The type 1 insulin-like growth factor receptor (IGF1R) mediates tumor cell growth, adhesion, and protection from apoptosis. High plasma IGF-I levels predispose to prostate cancer, but there is no consensus regarding IGF1R expression in primary and metastatic prostate cancer. Recent studies in a human cell line and a mouse model suggest that metastatic prostate cancer cell detachment may be favored by impairing cadherin function via loss of expression of insulin receptor substrate-1 (IRS-1), the principal IGF1R docking molecule. This may be accompanied by PTEN mutation, reactivating a key antiapoptotic pathway, and by IGF1R down-regulation to prevent Shc-mediated differentiation. We studied IGF1R expression in 54 samples of primary prostate tissue including 44 archival and 10 prospectively collected biopsies. We performed semiquantitative immunostaining for the IGF1R, IRS-1, and PTEN, and in situ hybridization for IGF1R. The IGF1R was significantly up-regulated at the protein and mRNA level in primary prostate cancer compared with benign prostatic epithelium. There was a trend toward increased expression of IRS-1 in the malignant biopsies. We also measured IGF1R, IRS-1, and PTEN expression in 12 paired biopsies of primary prostate cancer and subsequent bone metastases. In four cases, IGF1R and IRS-1 levels were lower in the metastases than in the primary tumors. Three of these metastases also lacked significant PTEN staining, compatible with findings in the model systems described above. However, this pattern was relatively uncommon, and 8 of 12 cases expressed detectable IGF1R and IRS-1 in both primary and metastatic biopsies. These findings challenge earlier reports of IGF1R down-regulation in metastatic disease and reinforce the importance of the IGF1R in prostate cancer biology.

Adenocarcinoma↗