Expression of androgen and estrogen related proteins in normal weight and obese prostate cancer patients.

BACKGROUND: Obesity is associated with an aggressive form of prostate cancer and with alterations in androgen and estrogen metabolism. We hypothesized that changes in components of the sex steroid receptor axis may contribute to the clinical aggressiveness of prostate cancer in obese patients. METHODS: A database was assembled containing clinical and pathological variables from 539 patients treated with radical prostatectomy at a single urban hospital between 1994 and 2002. Tissue microarrays were constructed from representative patients and expression of androgen receptor (AR), PSA, estrogen receptor alpha (ERalpha), estrogen receptor beta (ERbeta), and aromatase was examined. RESULTS: Higher BMI correlated strongly with black race, the presence of extra-capsular extension, and higher pathologic stage. Expression of AR, PSA, ERbeta and aromatase in cancerous epithelial cells did not differ according to obesity status. However, decreased expression of ERalpha and aromatase was observed in the stromal compartment surrounding non-cancerous acini in obese patients. CONCLUSION: We confirm the previously reported associations between obesity and aggressive clinical and pathologic features in our single-institution, urban teaching hospital. In comparing obese versus non-obese patients, there was no difference in expression of androgen or estrogen related proteins in cancerous epithelial cells. However, there was a down-regulation of ERalpha and aromatase in the stroma of obese patients. Our data suggest obesity may cause stromal changes in the sex steroid production and signaling pathways which may affect prostate cancer growth via intracrine/paracrine mechanisms.

Successful treatment of metastatic androgen-independent prostate carcinoma in a transsexual patient.

The occurrence of prostate carcinoma in transsexual patients has rarely been reported. These cases present a unique challenge in that such patients are effectively receiving androgen deprivation therapy. By definition, their disease is androgen-independent prostate cancer, and the role of local therapy is undefined. We report on a male-to-female transsexual patient with metastatic prostate cancer treated successfully with combination chemotherapy after previous standard therapy failed.

In vitro selection of external guide sequences for directing RNase P-mediated inhibition of viral gene expression.

External guide sequences (EGSs) are small RNA molecules that bind to a target mRNA, form a complex resembling the structure of a tRNA, and render the mRNA susceptible to hydrolysis by RNase P, a tRNA processing enzyme. An in vitro selection procedure was used to select EGSs that direct human RNase P to cleave the mRNA encoding thymidine kinase (TK) of herpes simplex virus 1. One of the selected EGSs, TK17, was at least 35 times more active in directing RNase P in cleaving TK mRNA in vitro than the EGS derived from a natural tRNA sequence. TK17, when in complex with the TK mRNA sequence, resembles a portion of tRNA structure and exhibits an enhanced binding affinity to the target mRNA. Moreover, a reduction of 95 and 50% in the TK expression was found in herpes simplex virus 1-infected cells that expressed the selected EGS and the EGS derived from the natural tRNA sequence, respectively. Our study provides direct evidence that EGS molecules isolated by the selection procedure are effective in tissue culture. These results also demonstrate the potential for using the selection procedure as a general approach for the generation of highly effective EGSs for gene-targeting application.

Engineered RNase P ribozymes inhibit gene expression and growth of cytomegalovirus by increasing rate of cleavage and substrate binding.

We have previously employed an in vitro (genetic) selection procedure to select RNase P ribozyme variants for their activity in cleaving a mRNA substrate from a pool of ribozymes containing randomized sequences. In this study, one of the variants was used to target the overlapping region of the mRNAs encoding the major transcription regulatory proteins, IE1 and IE2, of human cytomegalovirus (HCMV). The ribozyme variant exhibited an enhanced substrate binding and rate of chemical cleavage, and was at least 25 times more efficient in cleaving the target mRNA in vitro than the ribozyme derived from the wild-type sequence. Our results provide the first direct evidence that a point mutation at nucleotide 86 of RNase P catalytic RNA from Escherichia coli (A(86)-->C(86)) increases the rate of chemical cleavage while another mutation at nucleotide 205 (G(205)-->C(205)) enhances substrate binding of the ribozyme. Moreover, the variant was also more effective in inhibiting IE1 and IE2 expression and HCMV growth in cultured cells. A reduction of more than 97% in IE1 and IE2 expression and a reduction of 3000-fold in viral growth were observed in cells expressing the variant. Thus, RNase P ribozyme variant is highly effective in inhibiting HCMV gene expression and growth. Our results provide the direct evidence that increasing the rate of chemical cleavage and substrate-binding affinity of the ribozymes should lead to an improvement of their anti-HCMV efficacy. Moreover, our data also suggest that highly effective anti-HCMV ribozyme variants can be developed using genetic engineering approaches including in vitro selection.