Ronald Rodriguez

miR-21: an androgen receptor-regulated microRNA that promotes hormone-dependent and hormone-independent prostate cancer growth.

Androgen receptor (AR)-mediated oncogenic pathways have not been fully elucidated. In this study, we used high-throughput microarray analysis on two AR-positive prostate cancer (CaP) cell lines to identify 16 AR-responsive microRNAs (miRNA). We focused on miR-21 because of its previously reported oncogenic activity in other cancers. We show androgen-induced AR binding to the defined miR-21 promoter, miPPR-21, suggesting direct transcriptional regulation. Inhibition of miR-21 diminished androgen-induced CaP cell proliferation, providing new evidence that miRNAs can contribute to androgen-driven cell growth. Elevated expression of miR-21 enhanced CaP tumor growth in vivo and, surprisingly, was sufficient for androgen-dependent tumors to overcome castration-mediated growth arrest. Thus, elevated miR-21 expression alone is sufficient to impart castration resistance. Moreover, quantitative reverse transcription-PCR analysis revealed elevated miR-21 expression in CaP when compared with adjacent normal tissue. These results suggest that miR-21 may contribute to CaP pathogenesis.

Biodistribution, Tumor Detection, and Radiation Dosimetry of 18F-DCFBC, a Low-Molecular-Weight Inhibitor of Prostate-Specific Membrane Antigen, in Patients with Metastatic Prostate Cancer

Prostate-specific membrane antigen (PSMA) is a type II integral membrane protein expressed on the surface of prostate cancer (PCa) cells, particularly in androgen-independent, advanced, and metastatic disease. Previously, we demonstrated that N-[N-[(S)-1,3-dicarboxypropyl]carbamoyl]-4-18F-fluorobenzyl-l-cysteine (18F-DCFBC) could image an experimental model of PSMA-positive PCa using PET. Here, we describe the initial clinical experience and radiation dosimetry of 18F-DCFBC in men with metastatic PCa. Methods: Five patients with radiologic evidence of metastatic PCa were studied after the intravenous administration of 370 MBq (10 mCi) of 18F-DCFBC. Serial PET was performed until 2 h after administration. Time–activity curves were generated for selected normal tissues and metastatic foci. Radiation dose estimates were calculated using OLINDA/EXM 1.1. Results: Most vascular organs demonstrated a slow decrease in radioactivity concentration over time consistent with clearance from the blood pool, with primarily urinary radiotracer excretion. Thirty-two PET-positive suspected metastatic sites were identified, with 21 concordant on both PET and conventional imaging for abnormal findings compatible with metastatic disease. Of the 11 PET-positive sites not identified on conventional imaging, most were within the bone and could be considered suggestive for the detection of early bone metastases, although further validation is needed. The highest mean absorbed dose per unit administered radioactivity (μGy/MBq) was in the bladder wall (32.4), and the resultant effective dose was 19.9 ± 1.34 μSv/MBq (mean ± SD). Conclusion: Although further studies are needed for validation, our findings demonstrate the potential of 18F-DCFBC as a new positron-emitting imaging agent for the detection of metastatic PCa. This study also provides dose estimates for 18F-DCFBC that are comparable to those of other PET radiopharmaceuticals such as 18F-FDG.

Renal medullary carcinoma: clinical, pathologic, immunohistochemical, and genetic analysis with pathogenetic implications

OBJECTIVES To investigate the pathologic, clinical, and genetic features of renal medullary carcinomas (RMCs) in search of clues to their pathogenesis. METHODS We analyzed 40 RMCs for clinical features, for immunohistochemical expression using a panel of markers, and for genetic changes using comparative genomic hybridization. RESULTS Patients presented at 5 to 32 years of age, and 82% were African American. All patients tested had sickle cell trait or disease. Seven patients presented with suspected renal abscess or urinary track infection without a clinically recognizable mass. Of the 15 tumors able to be analyzed, all were positive for epithelial markers CAM 5.2 and epithelial membrane antigen. All were negative for high-molecular-weight cytokeratin 34betaE12. Cytokeratins 7 and 20 and carcinoembryonic antigen were heterogeneous and variable. Ulex was focally positive in a minority of cases. Eight of 12 tumors showed significant positivity for TP53 protein (greater than 25% nuclear positivity). All tumor tested (n = 8) were strongly positive for vascular endothelial growth factor and hypoxia inducible factor. Of nine tumors analyzed for genetic gains and losses using comparative genomic hybridization, eight showed no changes and one showed loss of chromosome 22. Survival ranged from 2 weeks to 15 months (mean 4 months). CONCLUSIONS These findings suggest that RMC is clinically and pathologically distinct from collecting duct carcinoma. The hypothesis that chronic medullary hypoxia secondary to hemoglobinopathy may be involved in the pathogenesis of RMC is suggested by strong vascular endothelial growth factor and hypoxia inducible factor expression and positivity for TP53.

IN VITRO FERTILIZATION IS ASSOCIATED WITH AN INCREASED RISK OF HYPOSPADIAS

PURPOSE The purpose of this study was to determine if there is an increased incidence of hypospadias in male offspring conceived by in vitro fertilization (IVF). MATERIALS AND METHODS A retrospective institutional chart review from 1988 to 1992 and data from the Maryland Birth Defects Registry were statistically analyzed to assess the risk of hypospadias with IVF. RESULTS The data for the 5-year period indicated a 5-fold increased risk of hypospadias after IVF, with an incidence of approximately 1.5% in the IVF group and 0.3% in the control group. The only recognized difference between the groups was maternal progesterone administration in the IVF group but the cause of the increased risk of hypospadias was unknown. The distribution of hypospadias severity was similar in both groups. CONCLUSIONS Male newborns conceived by IVF have a 5-fold increased risk of hypospadias, which may be related to maternal progesterone administration, or other maternal or fetal endocrine abnormalities that may or may not be related to infertility. Health care providers should be aware of this risk so that they can properly counsel infertile couples seeking assisted reproduction by IVF technology.

Renal ablative cryosurgery in selected patients with peripheral renal masses

OBJECTIVES To present the preliminary results of renal ablative cryosurgery in selected patients. METHODS Seven patients were treated, all of whom had small peripheral tumors and chose not to undergo partial or radical nephrectomy. Four patients underwent a rib-sparing flank incision; the remaining three underwent laparoscopy. All tumors were biopsied before cryoablation. Intraoperative ultrasound was used to monitor the cryolesion. RESULTS There were no intraoperative complications. The estimated blood loss averaged 111 mL. To date, 6 of the 7 patients have undergone at least one follow-up computed tomography scan (14.2 months average follow-up); all these scans demonstrated partial resolution of the lesion. Clinically, the patients tolerated the procedure without any renal complications or significant changes in creatinine. CONCLUSIONS This limited clinical trial has demonstrated the feasibility of treating small peripherally located renal tumors with cryosurgery with minimal morbidity and a favorable outcome. Further studies are necessary to determine the long-term efficacy of this treatment modality.

Chronic administration of valproic acid inhibits prostate cancer cell growth in vitro and in vivo

Valproic acid (VPA) is an established drug in the long-term therapy of seizure disorders. Recently, VPA has been associated with anticancer activity, an effect thought to be mediated through the inhibition of cellular histone deacetylase 1. We investigated the effect of various doses of VPA (0, 1.2, and 5.0 mmol/L) administered either acutely or chronically on histone acetylation, p21 gene expression, androgen receptor expression, prostate-specific antigen (PSA) expression, and cell survival and proliferation in prostate cancer cell lines. We also studied the effect of chronic VPA on tumor xenograft growth in vivo. Our results show that acute treatment (3 days) VPA can increase net histone H3 acetylation and up-regulate p21, AR, and cytosolic PSA expression. Interestingly, the effects on AR and PSA are reversed with chronic treatment. In addition, acute VPA reduces cell survival but has no effect on the subsequent proliferation of surviving cells following drug withdrawal. However, when VPA is chronically administered (10-14 days) to prostate cancer cells, even lower doses of VPA result in marked decreases in the net proliferation rate, correlating with increased caspase-2 and caspase-3 activation. These effects are evident in both androgen receptor-positive (LNCaP and C4-2) and androgen receptor-negative (DU145 and PC3) prostate cancer cells. Moreover, chronic VPA treatment results in statistically significant reduction of tumor xenograft growth in vivo. We conclude that acute treatment has nominal effects on prostate cancer cell survival and proliferation, but chronic VPA results in profound decreases in proliferation, independently of androgen regulation.

Integrin αv and coxsackie adenovirus receptor expression in clinical bladder cancer

Objectives. To evaluate the expression of the coxsackie and adenovirus receptor (CAR) and αv integrins in clinical specimens of bladder cancer to determine the susceptibility to adenoviral gene therapy. Efficient adenovirus-based gene therapy requires binding of the virus to CAR and involves the αv integrins. Studies on bladder cancer cell lines have shown that low adenoviral transduction rates were associated with low-level expression of CAR. Integrin αv expression increases in various tumors suggest its importance in differentiation, proliferation, and migration. CAR is structurally a member of the Ig-type superfamily of cell-cell adhesion molecules, suggesting that its expression may also be related to the state of tumor differentiation. Methods. We performed immunohistochemistry for CAR and integrin αv expression in bladder cancer specimens in 50 paraffin-embedded tumor-normal pairs and confirmed the results by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of 11 separate bladder tumors and 4 separate normal bladder controls. Results. Immunochemistry demonstrated a stage and grade-dependent decrease in CAR expression (90.0%, 83.3%, and 31.3% of normal urothelium and superficial and invasive transitional cell carcinoma [TCC] and 83.3% and 39.5% of low and high-grade TCC, respectively). Furthermore, we found a stage and grade-dependent increase in αv integrin expression (13.3%, 46.0%, and 56.3% of normal urothelium, superficial TCC, and invasive TCC and 25% and 52.6% of low and high-grade TCC, respectively). Quantitative RT-PCR analysis confirmed a downregulation at the CAR gene expression level. Conclusions. This down-regulation may have a major impact on developing adenoviral-based gene therapy modalities. In addition, we propose that loss of CAR expression decreases rigid cell adhesion, possibly increasing the migratory potential. Loss of CAR expression correlates with the invasive phenotype in our analysis of bladder cancer. Simultaneously, the finding of increased αv expression in invasive cancer suggests a pathogenesis that involves heterophilic adhesion and migration of these cells on various extracellular ligands.

Effects of curcumin on bladder cancer cells and development of urothelial tumors in a rat bladder carcinogenesis model.

Curcumin, a well-known dietary pigment derived from Curcuma longa, inhibited growth of several types of malignant cells both in vivo and in vitro. Its effects on cell proliferation and the induction of apoptosis in human bladder cancer cell lines and intravesical activity in a rat bladder tumor model were studied. Exposure of human bladder cancer cells to curcumin resulted in the induction of apoptotic cell death and caused cells to arrest in the G2/M phase. The anti-apoptotic Bcl-2 and Survivin protein was downregulated by the curcumin treatment together with enhancement of the Bax and p53 expression. The inhibitory activities of curcumin were stronger than those of cisplatin and could not be prevented by catalase pretreatment in T24 cells. Clonal assay indicated large-dose and short-term curcumin was lethal to bladder cancer cells. Moreover, the in vivo study revealed curcumin did induce apoptosis in situ, inhibit and slow the development of bladder cancer. These observations suggest that curcumin could prove an effective chemopreventive and chemotherapy agent for bladder cancer.

Gene therapy-mediated delivery of targeted cytotoxins for glioma therapeutics

Restricting the cytotoxicity of anticancer agents by targeting receptors exclusively expressed on tumor cells is critical when treating infiltrative brain tumors such as glioblastoma multiforme (GBM). GBMs express an IL-13 receptor (IL13Rα2) that differs from the physiological IL4R/IL13R receptor. We developed a regulatable adenoviral vector (Ad.mhIL-4.TRE.mhIL-13-PE) encoding a mutated human IL-13 fused to Pseudomonas exotoxin (mhIL-13-PE) that specifically binds to IL13Rα2 to provide sustained expression, effective anti-GBM cytotoxicity, and minimal neurotoxicity. The therapeutic Ad also encodes mutated human IL-4 that binds to the physiological IL4R/IL13R without interacting with IL13Rα2, thus inhibiting potential binding of mhIL-13-PE to normal brain cells. Using intracranial GBM xenografts and syngeneic mouse models, we tested the Ad.mhIL-4.TRE.mhIL-13-PE and two protein formulations, hIL-13-PE used in clinical trials (Cintredekin Besudotox) and a second-generation mhIL-13-PE. Cintredekin Besudotox doubled median survival without eliciting long-term survival and caused severe neurotoxicity; mhIL-13-PE led to ∼40% long-term survival, eliciting severe neurological toxicity at the high dose tested. In contrast, Ad-mediated delivery of mhIL-13-PE led to tumor regression and long-term survival in over 70% of the animals, without causing apparent neurotoxicity. Although Cintredekin Besudotox was originally developed to target GBM, when tested in a phase III trial it failed to achieve clinical endpoints and revealed neurotoxicity. Limitations of Cintredekin Besudotox include its short half-life, which demanded frequent or continued administration, and binding to IL4R/IL13R, present in normal brain cells. These shortcomings were overcome by our therapeutic Ad, thus representing a significant advance in the development of targeted therapeutics for GBM.

Immunoexpression Status and Prognostic Value of mTOR and Hypoxia-induced Pathway Members in Primary and Metastatic Clear Cell Renal Cell Carcinomas

The need for effective targeted therapies for renal cell carcinomas (RCCs) has fueled the interest for understanding molecular pathways involved in the oncogenesis of kidney tumors. Aiming to analyze the expression status and prognostic significance of mTOR and hypoxia-induced pathway members in patients with clear cell RCC (ccRCC), tissue microarrays were constructed from 135 primary and 41 metastatic ccRCCs. Immunoexpression levels were compared and correlated with clinicopathologic parameters and outcome. PTEN levels were significantly lower in primary and metastatic ccRCCs compared with benign tissues (P<0.001). Levels of phos-AKT, phos-S6, and 4E-binding protein-1 (4EBP1) were higher in metastatic ccRCC (P⩽0.001). For phos-S6 and 4EBP1, levels were higher in primary ccRCC compared with benign tissues (P<0.001). c-MYC levels were higher in metastatic ccRCC (P<0.0001), and incremental p27 levels were observed in benign, primary ccRCC, and metastatic ccRCC (P<0.0001). HIF-1&agr; levels were significantly higher in primary and metastatic ccRCCs compared with benign tissues (P<0.0001). In primary ccRCC, levels of all mTOR and hypoxia-induced pathway members were significantly associated with pT stage (P⩽0.036), p27 levels with Fuhrman grade (P=0.031), and 4EBP1, p27, and HIF-1&agr; levels with tumor size (P⩽0.025). Tumor size, HIF-1&agr;, and phos-S6 levels were associated with disease-specific survival (DSS) (P⩽0.032) and tumor progression (P⩽0.043). In conclusion, both mTOR and hypoxia-induced pathways were activated in primary and metastatic ccRCC. PTEN loss seems to be an early event during tumorigenesis. Tumor size, HIF-1&agr;, and phos-S6 expression were found to be independent predictors of both DSS and tumor progression in primary ccRCC.