Hao Zeng

BCL-xL Is a Target Gene Regulated by Hypoxia-inducible Factor-1α

The transcription factor hypoxia-inducible factor-1α (HIF-1α) plays pivotal roles in physiology and pathophysiology. Constitutive or hypoxia-induced HIF-1α overexpression is observed in many types of cancers including prostate adenocarcinoma, in which it is associated with resistance to apoptosis and therapeutic agents. BCL-xL, a hypoxia-responsive, anti-apoptotic protein of the Bcl-2 family, is also overexpressed in prostate carcinoma and many other cancers. Despite this connection, whether BCL-xL expression is directly regulated by HIF-1α is not known. We used prostate cancer PC-3 cell with constitutive high HIF-1α level as a model to address this important question. We first generated prostate cancer PC-3 cells in which HIF-1α was stably knocked-down (HIF-KD) by using small interference RNA. BCL-xL was dramatically decreased in HIF-KD PC-3 cells, in parallel with sensitization to apoptosis with caspase-3 activation as well as decreased cell proliferation. We then demonstrated that HIF-1α directly regulated BCL-xL transcription by binding to a hypoxia-responsive element in the BCL-xL promoter (-865 to -847) by reporter gene assay, chromatin immunoprecipitation, and electrophoretic mobility shift and supershift assays. HIF-1α-dependent BCL-xL overexpression may be an important mechanism by which HIF-1α protects prostate cancer cells from apoptosis and leads to treatment resistance.

MicroRNA145 Targets BNIP3 and Suppresses Prostate Cancer Progression

The putative tumor suppressor miR145 is transcriptionally regulated by TP53 and is downregulated in many tumors; however, its role in prostate cancer is unknown. On the other hand, BCL2/adenovirus E1B 19-kDa interacting protein 3 (BNIP3) is overexpressed in various tumors, including prostate cancer, and may transcriptionally repress the apoptosis-inducing factor (AIF) gene. Although BNIP3 transcription is controlled by hypoxia-inducible factor 1alpha (also elevated in prostate cancer), we postulated the posttranscriptional regulation of BNIP3 by miR145 through bioinformatics analysis, and herein we experimentally showed that miR145 negatively regulated BNIP3 by targeting its 3-untranslated region. Artificial overexpression of miR145 by using adenoviral vectors in prostate cancer PC-3 and DU145 cells significantly downregulated BNIP3, together with the upregulation of AIF, reduced cell growth, and increased cell death. Artificial overexpression of wild-type TP53 in PC-3 cells (which lack TP53 protein) and DU145 cells (in which mutated nonfunctioning TP53 is expressed) significantly upregulated miR145 expression with consequent effects on BNIP3 and cell behavior as with miR145 overexpression. Analysis of prostate cancer (n = 134) and benign prostate (n = 83) tissue sample showed significantly decreased miR145 and increased BNIP3 expression in prostate cancer (P < 0.001), particularly in those with tumor progression, and both molecular changes were associated with unfavorable outcome. Abnormalities of the miR145-BNIP3 pair as part of TP53-miR145-BNIP3-AIF network may play a major role in prostate cancer pathogenesis and progression.

A functional insertion/deletion polymorphism in the promoter region of the NFKB1 gene increases susceptibility for prostate cancer

Among men, cancers of the prostate, lung and bronchus, and colon and rectum account for about 50% of all newly diagnosed cancers, and prostate cancer alone accounts for about 25% of incident cases. Nuclear factor-kappaB (NF-kappaB)-activation plays a critical role in prostate cancer by NF-kappaB inhibitor kinase beta pathway-mediated inflammatory-induced tumorigenesis. A functional insertion/deletion polymorphism (-94 insertion/deletion ATTG) in the promoter of the NFKB1 gene, which encodes the p50 subunit of NF-kappaB, was identified recently. A total of 117 prostate cancer patients and 143 control subjects were recruited in this study. The NFKB1 -94 insertion/deletion ATTG genotype was determined using polymerase chain reaction-polyacrylamide gel electrophoresis. The frequency of the ATTG(2) allele in prostate cancer patients was significantly higher than that in the controls (63.7 vs. 54.5%; P=0.035, OR=1.461). Prostate cancer patients with a history of prostatitis have a 2.275 times higher risk for prostate cancer, compared to the control group (P=0.001). The functional NFKB1 promoter polymorphism is associated with increased risk of prostate cancer.

Evaluation of Interleukin-8 in Expressed Prostatic Secretion as a Reliable Biomarker of Inflammation in Benign Prostatic Hyperplasia

OBJECTIVESnTo evaluate the efficacy of interleukin-8 (IL-8) as a possible biomarker for diagnosis and treatment of benign prostatic hyperplasia (BPH) with chronic prostatitis. Histologic inflammation can be demonstrated in most BPH pathologic specimens. To provide objective parameters of inflammation, this prospective study quantified the IL-8 in expressed prostatic secretion (EPS) from BPH patients with or without histologic inflammation.nnnMETHODSnWhite blood cell (WBC) count and enzyme-linked immunosorbent assays of the EPS for IL-8 were done in 44 patients who underwent transurethral prostatic resection because of benign prostatic enlargement before the operations. The correlation between IL-8 and WBC count in EPS; prostatic specific antigen; and International Prostate Symptom Score, irritative, and obstructive subscores was determined by Pearson correlation analysis.nnnRESULTSnIL-8 was detectable in all patients (the threshold of detection for IL-8 is 5 pg/mL). Twenty-one (47.7%) BPH patients had chronic prostatitis. The mean level of IL-8 in EPS was higher in BPH with chronic prostatitis than in simple BPH (median +/- SE, 8175 +/- 3789 pg/mL vs 2806 +/- 1009 pg/mL). The catheter and age seemed to have no impact on the level of IL-8 in EPS. Statistically significant correlation was only found between IL-8 and WBC count. The sensitivity and specificity of IL-8 in EPS identifying the BPH with chronic prostatitis from the simple BPH were 85.7% and 91.3% respectively, at a cut-point of 3992 pg/mL.nnnCONCLUSIONSnIL-8 is significantly elevated in BPH patients with chronic prostatitis. IL-8 in EPS can serve as a reliable biomarker applicable to identifying BPH with chronic prostatitis from simple BPH.

Twenty-five Cases of Adult Prostate Sarcoma Treated at a High-volume Institution From 1989 to 2009

OBJECTIVEnTo analyze the clinical characteristics, treatment modalities, and outcomes of adult prostate sarcoma treated at our institution.nnnMATERIALS AND METHODSnThe medical records of 25 adult patients with prostate sarcoma were obtained from January 1989 to December 2009. The clinicopathologic parameters were evaluated to determine their effect on survival.nnnRESULTSnThe median age was 37 years (range 18-81). The median tumor size was 9.5 cm (range 4-25). The median serum prostate-specific antigen level was 1.39 ng/mL (range 0.39-33.20). The most common symptom was dysuria (72%). Transrectal ultrasound-guided needle biopsy was used to diagnose 22 sarcomas, transurethral resection of the prostate to diagnose 2, and open surgery to diagnose 1. The predominant histologic subtype was leiomyosarcoma (40%); 21 (88%) were high grade and 6 patients had metastatic disease. Surgical resection of curative intent was performed in 14 patients, with negative margins in 10. After a median follow-up of 21 months (range 5-63), 2 patients were disease free, 4 were alive with disease, and 19 had died of their disease. Overall, the 1-, 2-, 3-, and 5-year survival rate was 80.0%, 47.4%, 22.6%, and 11.3%, respectively, and the median survival time was 23 months. The median survival time after recurrence was 20 months (range 9-39) and that after metastasis was 10 months (range 3-23). Age >50 years, metastasis at presentation, and a lack of surgery with curative intent were independently predictive of an unfavorable outcome.nnnCONCLUSIONnAdult prostate sarcoma accounted for 0.7% of primary prostate malignancies and carried a poor prognosis. Early diagnosis and surgical resection with curative intent offer patients the best chance of survival.

Multifocal Brain Metastases in Clear Cell Renal Cell Carcinoma with Complete Response to Sunitinib

We report the case of a 70-year-old man who received sunitinib treatment for brain metastatic clear cell renal cell carcinoma. After 6 months of treatment, brain MRI showed complete disappearance of two brain metastases. To the best of our knowledge, this is the first reported case of multifocal brain metastases in renal cell carcinoma with complete response to sunitinib.

Adult Renal Sarcoma: Clinical Features and Survival in a Series of Patients Treated at a High-volume Institution

OBJECTIVESnTo examine the clinical characteristics, treatment, and survival of adult patients with renal sarcoma treated at our institution during the past 2 decades.nnnMETHODSnA retrospective review of the demographic, presentation, treatment, and outcome data for 41 adult patients with renal sarcoma treated at our institution from January 1989 to December 2009 was performed. The clinicopathologic parameters were analyzed to determine their effect on survival.nnnRESULTSnOf the 41 patients, 18 were women and 23 were men. Their median age was 42 years (range 19-76). The median tumor size was 13 cm (range 4-35); 29 cases (70.7%) were high grade. The predominant histologic subtype was leiomyosarcoma (39.0%). At diagnosis, 6 patients (14.6%) had metastatic disease. Surgical resection was performed in 34 patients (82.9%), with negative margins in 22 (53.7%). After a median follow-up of 24 months (range 3-80), 3 patients (8.1%) had survived disease free, 11 (29.7%) were alive with disease, and 23 (62.2%) had died of disease. The overall 1-, 3-, and 5-year survival rate was 86.3%, 40.7%, and 14.5%, respectively, and the median survival was 28 months. The median survival after recurrence was 10 months (range 4-24) and that after metastasis 8 months (range 0-22). On univariate analyses, nonmetastatic disease (P = .001) and surgical resection (P = .000) were predictive of a favorable outcome. On multivariate analyses, surgical resection was the only independent predictor of survival (hazard ratio 35.629, P = .022).nnnCONCLUSIONSnAdult renal sarcoma accounts for 0.8% of renal cancer cases and has a poor prognosis. Early diagnosis and surgical resection offer patients the best chance of survival.

Adrenal and Extra-Adrenal Nonfunctioning Composite Pheochromocytoma/Paraganglioma with Immunohistochemical Ectopic Hormone Expression: Comparison of Two Cases

Adrenal composite pheochromocytoma is rare, most of which is functional, and extra-adrenal composite paraganglioma is extremely rare. We describe and compare the clinicopathological and immunohistochemical features of a retroperitoneal extra-adrenal composite paraganglioma and an adrenal composite pheochromocytoma. Both tumors were nonfunctioning and laboratory tests revealed no biochemical abnormalities. Both tumors were composed of typical paraganglioma/pheochromocytoma closely admixed with ganglioneuroma component. In addition to typical immunohistochemical phenotypes characteristic of each component, both tumors showed focal staining of somatostatin, and the adrenal tumor was also regionally positive for insulin and prolactin. Despite this aberrant immunohistochemical expression, relevant clinical symptoms or laboratory abnormalities were absent. These tumors serve to exemplify the extremely rare occurrences of clinically silent, nonfunctioning composite pheochromocytoma or paraganglioma with aberrant expression of hormones.

Synergistic Silencing by Promoter Methylation and Reduced AP-2α Transactivation of the Proapoptotic HRK Gene Confers Apoptosis Resistance and Enhanced Tumor Growth

The Harakiri (HRK) gene encodes an important proapoptotic mitochondrial protein of the Bcl-2 family. HRK is expressed in normal tissues but is decreased in many cancers such as melanoma, the mechanisms of which have not been fully elucidated. Here, we demonstrate that HRK is silenced by hypermethylation of a major proximal CpG island in the HRK promoter. Furthermore, we show that HRK is a novel target gene regulated by the transcription factor AP-2α, which interacts with an AP-2α binding site in the HRK promoter. Hypermethylation of the major proximal CpG island (which contains the AP-2α binding site within the most densely methylated -218- to -194-bp region) inhibited AP-2α binding and transcriptional activity. Artificial overexpression of AP-2α in melanoma cells up-regulated HRK transcription, which was further restored by treatment with DNA methyltransferase inhibitor 5-azacytidine. Artificial overexpression of HRK by recombinant adenovirus induced caspase-dependent apoptosis, inhibited melanoma cell growth inxa0vitro, and markedly reduced inxa0vivo melanoma growth in a nude mouse xenograft model. RNA interference by siHRK or siAP-2α reversed the above effects. We conclude that the synergistic effects of HRK promoter hypermethylation and loss of AP-2α transactivation lead to HRK gene silencing and confer resistance to apoptosis and enhanced tumor growth. These novel molecular lesions may provide the basis for new therapeutic approaches to treating AP-2α- and HRK-deficient cancers.

Improved effects of a double suicide gene system on prostate cancer cells by targeted regulation of prostate-specific membrane antigen promoter and enhancer

Objective:u2003 To explore the specific killing effect on prostate cancer cells of a dual cytosine deaminase (CD) and uracil phosphoribosyltransferase (UPRT) expression plasmid system controlled by the prostate‐specific membrane antigen (PSMA) promoter and enhancer.