Follicular growth and oocyte competence in the in vitro cultured mouse follicle: effects of gonadotrophins and steroids.

Although there have been extensive studies on the effects of gonadotrophins and steroids on follicular development, less is known as to the effects these hormones have on the acquisition of oocyte developmental competence. This study investigates the effect of altering the gonadotrophin or steroidal environment on follicular development and on oocyte viability and DNA methylation. Oocytes were obtained from pre-ovulatory follicles after individual follicle culture from the pre-antral stage; gonadotrophin or steroid levels were manipulated during the culture period. Oocytes obtained from follicles grown in gonadotrophin free conditions were able to fertilize and develop to the blastocyst stage despite their impaired follicle development. There was no effect of luteinizing hormone or steroids on follicular growth. Altering the steroidal environment did, however, affect oocyte development. The oocytes of follicles exposed to high estrogen levels had lower fertilization rates, regardless of the presence or absence of high androgen levels. The combined presence of high levels of both steroids altered the level of global methylation. This study demonstrates that gonadotrophins and steroids influence the acquisition of developmental competence of the oocyte and suggests that optimal steroid exposure during follicle development is required for the oocyte to mature correctly.

Hypoxia in prostate cancer: correlation of BOLD-MRI with pimonidazole immunohistochemistry-initial observations.

PURPOSE: To investigate the ability of blood oxygen level-dependent (BOLD) MRI to depict clinically significant prostate tumor hypoxia. METHODS AND MATERIALS: Thirty-three patients with prostate carcinoma undergoing radical prostatectomy were studied preoperatively, using gradient echo sequences without and with contrast medium enhancement, to map relative tissue oxygenation according to relaxivity rates and relative blood volume (rBV). Pimonidazole was administered preoperatively, and whole-mount sections of selected tumor-bearing slices were stained for pimonidazole fixation and tumor and nontumor localization. Histologic and imaging parameters were independently mapped onto patient prostate outlines. Using 5-mm grids, 861 nontumor grid locations were compared with 237 tumor grids (with >50% tumor per location) using contingency table analysis with respect to the ability of imaging to predict pimonidazole staining. RESULTS: Twenty patients completed the imaging and histologic protocols. Pimonidazole staining was found in 33% of nontumor and in 70% of tumor grids. The sensitivity of the MR relaxivity parameter R(2)* in depicting tumor hypoxia was high (88%), improving with the addition of low rBV information (95%) without changing specificity (36% and 29%, respectively). High R(2)* increased the positive predictive value for hypoxia by 6% (70% to 76%); conversely, low R(2)* decreased the likelihood of hypoxia being present by 26% (70% to 44%) and by 41% (71% to 30%) when combined with rBV information. CONCLUSION: R(2)* maps from BOLD-MRI have high sensitivity but low specificity for defining intraprostatic tumor hypoxia. This together with the negative predictive value of 70% when combined with blood volume information makes BOLD-MRI a potential noninvasive technique for mapping prostatic tumor hypoxia.

An immunohistochemical assessment of hypoxia in prostate carcinoma using pimonidazole: implications for radioresistance.

PURPOSE: To investigate the presence of hypoxia in human prostate carcinoma by using pimonidazole immunohistochemical labeling in radical prostatectomy specimens. METHODS AND MATERIALS: Forty-three patients (median age, 69 years; range, 49-83 years) with localized prostate adenocarcinoma received 0.5 gm/m2 i.v. pimonidazole 16-24 h before radical prostatectomy. Hypoxia was detected with a monoclonal antibody directed against pimonidazole and scored in formalin-fixed, paraffin-embedded sections. Median and maximal vessel counts were measured with CD34. RESULTS: Thirty-seven patients completed the study. Pimonidazole binding was present in prostate carcinomas in 34 of 37 patients (92%) and in benign prostatic hyperplasia in 35 of 37 patients (95%). A positive correlation of 3+ pimonidazole binding with Gleason score was demonstrated (Spearman's rank, p = 0.044). Vascularity scores did not correlate with hypoxic status or clinical prognostic parameters. CONCLUSION: Prostate carcinoma and benign prostatic hyperplasia have significant areas of hypoxia; greater hypoxia scores are seen with more aggressive prostate cancer. It is postulated that a hypoxic microenvironment within the prostate might be responsible for the promotion of secondary genetic alterations and angiogenic stimulation, leading to malignant progression, a more aggressive cell phenotype, and greater radioresistance. Modification of radiation regimens to specifically target hypoxia might improve local tumor control.

Target validation of cytochrome P450 CYP1B1 in prostate carcinoma with protein expression in associated hyperplastic and premalignant tissue.

PURPOSE: To investigate the localization and distribution of cytochrome P450 CYP1B1 protein expression in patients diagnosed with prostate carcinoma compared to those with bladder carcinoma. To validate CYP1B1 as a molecular target for the development of selective cancer therapeutics for use in combination with radiation. METHODS AND MATERIALS: Prostatectomy specimens (n = 33) of moderate Gleason grade (3 + 3 and 3 + 4) were analyzed immunohistochemically for CYP1B1 protein expression using a specific monoclonal antibody for the enzyme. The intensity of CYP1B1 staining was assessed both semiquantitatively using visual scoring and quantitatively by spectral imaging microscopy using reference spectra and compared with bladder carcinoma (n = 22). RESULTS: CYP1B1 protein expression was present in 75% of prostate carcinomas (n = 27) compared to 100% of bladder carcinomas (n = 22). In both cases, CYP1B1 protein expression was heterogeneous and localized in the cytoplasm of the tumor cells but absent from the surrounding stromal tissue. CYP1B1 was also detected in premalignant prostatic intraepithelial neoplasia (n = 2, 100%), as well as noncancerous tissues, including benign prostatic hyperplasia (n = 27, 82%), metaplastic prostatic urothelium (n = 8, 100%), and hyperplastic prostatic urothelium (n = 14, 100%). Higher CYP1B1 protein expression in bladder vs. prostate carcinoma was confirmed by their corresponding average normalized absorbances (+/- standard deviation), measured as 1.40 +/- 0.44 and 0.55 +/- 0.09, respectively. Overall CYP1B1 staining intensity in prostate carcinoma was similar to that in prostatic intraepithelial neoplasia, benign prostatic hyperplasia, and hyper-/metaplastic urothelial tissue. No CYP1B1 was detected in normal prostate tissue. CONCLUSIONS: CYP1B1 is overexpressed in prostate carcinoma at a high frequency and is also detectable in the associated premalignant and hyperplastic tissue, implicating a possible link with malignant progression and CYP1B1 as a suitable target for therapy. Spectral imaging microscopy has highlighted differences in CYP1B1 protein expression between different cancers.