Androgen signaling regulates the PDCD4 tumor suppressor gene. In the February 2019 issue of Molecular Cancer Research, Kenji Zennami reports that androgen receptor signaling leads to the suppression of PDCD4 mRNA and protein expression through the induction of miR-21 expression. In cell and tumor models of Prostate Cancer, Kenji found PDCD4 knockdown to enhance cell proliferation, reduce apoptosis, augment tumorigenesis, and drive castration resistance. He also found, through collaboration with Luigi Marchionni, that high Gleason grade prostate cancers exhibit low levels of PDCD4 mRNA and high levels of miR-21. Read about it in Molecular Cancer Research.
AJA Outstanding Paper Award. Our 2016 review of microRNA expression and function was recognized with the AJA Outstanding Paper Award of 2018. We thank the Asian Journal of Andrology for this recognition.
Cell-type specific expression of miRNAs in prostate cancer. In the May 2018 issue of Scientific Reports, Binod Kumar examined the cell-type specific expression of oncogenic and tumor suppressive microRNAs in microdissected radical prostatectomy specimens. We worked with Marc Halushka and Avi Rosenberg from the Department of Pathology to apply expression microdissection (xMD), a developing technology where one can immunohistochemically stain a tissue slide and then capture all positively-stained cells. Through this technique, Binod found that some prostate cancer associated miRNAs were predominantly expressed in stromal cells, rather than cancer or epithelial cells. He was then able to compare expression of these miRNAs in the normal and cancer-associated stroma. This study was a collaborative effort between our laboratory, Marc Halushka’s laboratory, Luigi Marchionni’s laboratory, and Nate Brennen’s laboratory at Johns Hopkins and Larisa Nonn’s laboratory at the University of Illinois, Chicago. Read about it in Scientific Reports.
Promise and Progress. Our collaborative research with Dr. Ted DeWeese and the Department of Radiation Oncology and Molecular Radiation Sciences is featured in the May 2018 issue of Promise and Progress
Prostate cancer therapy through induced redox stress. In the February 2018 issue of the Prostate, Thiago Martino published his studies of an orally active pterocarpanquinone, LQB-118, in prostate cancer cell line and tumor models. His results show that LQB-118 is activated by quinone reduction, causing an increase in reactive oxygen species in treated cells. He found that LQB-118 treated cells induced the expression of genes, such as SOD1, to dampen reactive oxygen. The cytotoxicity of LQB-118 increased when these genes were inhibited by siRNAs or miRNAs. This study was a collaborative effort between our laboratory and the Rio de Janeiro State University (UERJ). Read about it in the Prostate.
Don Coffey, Aptamers, and Apple Pies. It was an incredible honor to edit a special issue of the American Journal of Clinical and Experimental Urology in memoriam and celebration of Donald S. Coffey, Ph.D. We were all so lucky to have known and worked with this extraordinary man. You can read our article and explore the entire issue at the AJCEU.
How long are microRNAs stable in archived tissues? In the January 6th, 2017 issue of BMC Cancer, Sarah Peskoe published an analysis of miRNA transcript levels in 12-20 year old archived formalin-fixed paraffin-embedded prostate cancer specimens. The levels of miRNA transcript levels decreased with sample age, indicating a clear loss of stability over time. RNU6B, a small nuclear RNA commonly applied to normalize for RNA sample loading, was the most rapidly degraded RNA among four other microRNAs. Different miRNAs also demonstrated differential rates of degradation. These results indicate that long-term archived FFPE samples may benefit from epidemiology study design to account for storage-dependent RNA degradation. This study resulted from our long-term collaborations with Johns Hopkins Pathology (De Marzo and Meeker Labs) and the Johns Hopkins School of Public Health (Elizabeth Platz team). Read about it in BMC Cancer.
What microRNAs regulate the Androgen Receptor and Androgen Receptor Signaling? In the November 8th, 2016 issue of Oncotarget, Dr. Binod Kumar published his work characterizing miRNAs that regulate the Androgen Receptor (AR) and AR Signaling. The AR is a nuclear hormone receptor that plays a key role in prostate biology and in the progression of prostate cancer to therapeutic resistance. A library of miRNA mimics was screened to identify miRNAs with the ability to alter AR protein expression, AR transcriptional activity, and AR-dependent cell viability. Several AR-regulating miRNAs were identified. These results confirmed previous discoveries of AR-regulating miRNAs and uncovered previously unrecognized AR-regulating miRNAs. Members of the miR-30 family were identified as inhibitors of the AR and AR signaling, and miR-30d-5p expression was found to be significantly lower in metastatic castration resistant cancers when compared to healthy prostate tissue. Read about it in Oncotarget:
Changing the Genes in Prostate Cancer. Laboratory research on alternative polyadenylation is featured in the Discovery Newsletter, Volume 12, Winter 2017.
MicroRNAs: Genes that May Make Radiation and Chemotherapy More Effective. Laboratory research featured in Discovery Newsletter, Special Centennial Edition, Winter 2016.
Greenberg Bladder Cancer Institute Award for bladder cancer research. We were fortunate to receive an award from the Greenberg Bladder Cancer Institute to study mechanisms of exceptional responders to therapy.
Can large macromolecular reagents be specifically targeted to prostate tumors? In August of 2016, Dr. Amar Mukherjee published his work with a model system to study active and passive tumor targeting. Active tumor targeting utilizes conjugated targeting ligands to direct reagent binding to cells through a tumor-specific receptor, while passive targeting relies on inert reagent uptake through leaky tumor vasculature. The results support that conjugated ligands can increase macromolecular reagent uptake within tumors. This targeting could be enhanced or inhibited by increasing the reagent size and circulating half-life, depending on the tumor model. These studies shed new light on tumor-targeted regents. Read about it in Molecular Cancer Therapy.
Delivering radiation-sensitizing reagents to prostate tumors. In December of 2015 Dr. Xiaohua Ni demonstrated that small interfering RNAs (siRNA) targeting the DNA repair gene, DNA-PK (PRKDC), could be delivered to PSMA-positive prostate cancer xenografts by linking them to the PSMA-targeting RNA aptamer, A10-3. After intravenous injection, the aptamer-siRNA conjugates selectively knocked down DNA-PK expression and enhanced the potency of external beam radiation therapy for PSMA-positive xenograft tumors. Read about it in Molecular Cancer Therapy.
miRNAs, DNA repair, and cancer susceptibility to ionizing radiation therapy. In April of 2015 Dr. Koji Hatano reported results of his high throughput miRNA mimic library screen to identify miRNAs that influence DNA repair pathways and prostate cancer cell sensitivity to ionizing radiation (IR) therapy. The screen identified miRNAs with anti-proliferative, IR protective, and IR sensitizing properties. Two potent IR-sensitizing miRNAs, miR-890 and miR-744-3p, were found to inhibit DNA repair by limiting the expression of several DNA repair genes including MAD2L2, WEE1, XPC, and RAD23B. The treatment of established prostate xenograft tumors with miR-890 mimics significantly enhanced IR therapeutic effects. Read about these studies in Nucleic Acids Research.
microRNAs and risk of recurrence after radical prostatectomy. In September of 2014 we reported the results of a study on three microRNAs, miR-221, miR-141, and miR-21, and their expression levels in prostate cancers which either recurred, or did not recur, after radical prostatectomy. The nested case-control study applied tumor tissue from 118 radical prostatectomy specimens which were matched for patient age, race, pathologic stage, and Gleason grade. However, only half of these patients had a later prostate cancer recurrence. The results found that lower miR-221 tumor expression was associated with a greater risk of recurrence. These preliminary studies may shed light on the biology of recurrent cancer. This work is the result of a collaborative group including the Departments of Pathology, Epidemiology, Oncology and Urology at the Johns Hopkins School of Medicine and the Bloomberg School of Public Health. Read about it in The Prostate.
Noncoding RNAs and RNA Therapeutics in prostate cancer. Brady Research Blog.
Recombinant adenovirus as Circulating Tumor Cell detection agents. In September of 2014 Dr. Ping Wu reported the development of a new approach for detecting Circulating Tumor Cells (CTCs) using recombinant adenoviral reporter vectors and secreted reporter genes. The study took a classic gene therapy approach, where recombinant adenovirus are engineered to selectively replicate and kill cancer cells, and converted it for detection purposes, to label and quantify the level of living prostate cancer cells in blood. This was accomplished by applying prostate gene regulatory elements to selectively turn on viral replication in prostate cancer cells. Then, after the viral genome has replicated, a secreted reporter gene was activated in concert with viral packaging genes. This reporter signal could then be detected in the cell media. These preliminary studies, published in The Prostate, explored the sensitivity and specificity of this new approach in a prostate CTC model using cancer cells diluted in blood. This was a highly collaborative project with the laboratory of Ronald Rodriguez here at the James Buchanan Brady Urological Institute. Read about it in The Prostate.
Exploiting prostate-specific genes as potential imaging reporters. In May of 2014 Dr. Mark Castanares published a study characterizing PSMA as a new imaging reporter gene. What is an imaging reporter? They are foreign genes which can be used to label cells, tissues or biologic activities. The corresponding cells or tissues can then be easily identified and measured over time using medical or biotechnological imaging methods. Good imaging reporter genes have naturally restricted gene expression, so that labelled cells stand out as shining beacons. PSMA is an ideal candidate because it has restricted expression to only a few select tissues. The manuscript compares PSMA to established imaging reporter genes and applies PSMA to PET, SPECT, and optical imaging. These preliminary studies indicate that PSMA may be a useful imaging reporter. This was a collaborative project with Marty Pomper’s lab in the Department of Radiology at the Johns Hopkins Division of Neuroradiology. Read about it in the Journal of Nuclear Medicine.
Optimizing a prostate-cancer targeted nanoparticle. In March of 2014 Dr. Amarnath Mukherjee published a manuscript in ChemMedChem describing a multidisciplinary effort to develop PSMA targeted iron oxide nanoparticles. In this study a series of silica coated iron oxide nanoparticles were develop with varying densities of surface-displayed polyethylene glycol and PSMA-targeting antibody. These nanoparticles were then screened for their targeting properties in small scale assays, such as spectral absorbance and ELISA, using multiwell plates. The nanoparticles with the best targeting properties had intermediate (rather than high) densities of polyethylene glycol and targeting ligand. These preliminary studies may shed light on future nanoparticle targeting strategies. This was a collaborative project with Robert Ivkov’s laboratory in the department of Radiation Oncology and Molecular Radiation Sciences at the Johns Hopkins University School of Medicine. Read about it in ChemMedChem.
Do cells respond differently to nanoparticle heating? In February of 2014 Dr. Amarnath Mukherjee published a study in Nanomedicine (UK) which evaluated cellular responses to mild hyperthermia from macroscopic sources (water baths) and nanoscopic sources (iron oxide nanoparticles stimulated for heating). By using a heat sensitive reporter system, Dr. Mukherjee could detect cellular responses to very mild and non-lethal heating doses. These preliminary results indicate that cells can detect mild heat stress from nanoparticles at temperatures too low to measurably alter the macroscopic temperature of the system. The results also suggest that cells which were closer to the nanoscopic heat source experienced greater thermal stress. Further work is needed in diverse nanoparticle systems to study these phenomona. This was a joint project with the laboratory of Robert Ivkov in the department of Radiation Oncology and Molecular Radiation Sciences at the Johns Hopkins University School of Medicine. Read about this study at Nanomedicine (UK).
New Way To Find Elusive Cancer Cells Floating in the Bloodstream: The Common Cold Virus? Laboratory research featured in Prostate Cancer Discover, Winter 2016.
The Prognostic Potential of microRNA in Prostate Cancer. Laboratory research featured by the Department of Defense
New insights into the miR-21 gene. In August of 2012 Dr. Judit Ribas published a manuscript in Nucleic Acids Research where she characterized the unique organization of the miR-21 gene. The miR-21 hairpin is located immediately downstream of a coding gene, VMP1, and is flanked by several polyadenylation signals. The VMP1 gene appears to primarily use the proximal polyadenylation signals, where pri-miR-21 appears to preferentially use the distal polyadenylation signals. Alternative polyadenylation of VMP1 transcripts can then also result in an alternative primary transcript of miR-21, VMP1-miR-21. It is not yet clear how these diverse pathways are used in biology. Read about this at Nucleic Acids Research.
Sensitizing prostate cancer to radiotherapy. Science Daily Featured Research Article (May 2011)
Sensitizing specific tissues to radiation therapy. In June of 2011 Dr. Xiaohua Ni published a manuscript in the Journal of Clinical Investigation where he explored the use of aptamers as siRNA targeting agents for radiation sensitization therapy. A high throughput screen was used to identify DNA-PK as an optimal target for siRNA-mediated radiation sensitization of prostate cancer cells. When DNA-PK specific siRNAs were conjugated to our PSMA-targeting RNA aptamer, A10-3, they could selectively sensitize prostate cancer cells and tumors to radiation therapy in an aptamer-specific and PSMA-specific manner. Additional studies are needed to determine if this approach can be translated to the clinical setting. This was a highly collaborative project with the DeWeese Laboratory in the department of Radiation Oncology and Molecular Radiation Sciences at the Johns Hopkins University School of Medicine. Read about this at JCI.
Selecting the optimized peptide-targeted adenovirus
In December of 2010 Dr. Ping Wu published a priority report in Cancer Research which described a process for developing and screening peptide-displayed adenovirus. The approach utilized a known PSMA targeting peptide, which was flanked by a library of randomized amino acid cassettes. The randomized cassettes theoretically provided a high diversity of environments for the targeting peptide and viral capsid protein to optimally fold. The screen resulted in a PSMA-targeted adenoviral vector. This effort was a highly collaborative project with the Rodriguez Laboratory at Johns Hopkins. Read about it in Cancer Research.
Androgenic Regulation of a microRNA Plays Critical Role in Prostate Cancer Progression. AACR Press Release, September 2009.
Does the androgen receptor regulate microRNA gene expression? Dr. Judit Ribas investigated whether non-coding microRNA genes were activated or suppressed by the Androgen Receptor in prostate cancer cells. The results, published in Cancer Research in September of 2009, found several androgen induced microRNAs, including one with oncogenic properties, miR-21. Elevated expression of miR-21 in prostate cancer model systems caused enhanced cell and tumor growth, as well as resistance to castration therapy. This was a collaborative project with the Mendell Laboratory at Johns Hopkins. Read about it in Cancer Research.
Podcast on Aptamer targeting agents
Brany Brews: Hopkins Magazine: Brainy Brews (2004)