Background: Cell entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) depends on binding of the viral spike (S) proteins to angiotensin-converting enzyme 2 and on S protein priming by TMPRSS2. Inhibition of TMPRSS2 may work to block or decrease the severity of SARS-CoV-2 infections. Intriguingly, TMPRSS2 is an androgen-regulated gene that is up-regulated in prostate cancer where it supports tumor progression and is involved in a frequent genetic translocation with the ERG gene. First-or second-generation androgen-deprivation therapies (ADTs) decrease the levels of TMPRSS2. Here we put forward the hypothesis that ADTs may protect patients affected by prostate cancer from SARS-CoV-2 infections. Materials and methods: We extracted data regarding 9280 patients (4532 males) with laboratory-confirmed SARS-CoV-2 infection from 68 hospitals in Veneto, one of the Italian regions that was most affected by the coronavirus disease 2019 (COVID-19) pandemic. The parameters used for each COVID-19-positive patient were sex, hospitalization, admission to intensive care unit, death, tumor diagnosis, prostate cancer diagnosis, and ADT. Results: There were evaluable 9280 SARS-CoV-2-positive patients in Veneto on 1 April 2020. Overall, males developed more severe complications, were more frequently hospitalized, and had a worse clinical outcome than females. Considering only the Veneto male population (2.4 million men), 0.2% and 0.3% of non-cancer and cancer patients, respectively, tested positive for SARS-CoV-2. Comparing the total number of SARS-CoV-2-positive cases, prostate cancer patients receiving ADT had a significantly lower risk of SARS-CoV-2 infection compared with patients who did not receive ADT (OR 4.05; 95% CI 1.55e10.59). A greater difference was found comparing prostate cancer patients receiving ADT with patients with any other type of cancer (OR 4.86; 95% CI 1.88e12.56). Conclusion: Our data suggest that cancer patients have an increased risk of SARS-CoV-2 infections compared with noncancer patients. However, prostate cancer patients receiving ADT appear to be partially protected from SARS-CoV-2 infections.

Small interfering RNAs (siRNAs) directed to gene promoters can silence genes at the transcriptional level. siRNA-directed transcriptional silencing (RdTS) was first described in plants and yeasts and more recently in mammalian cells. RdTS has been associated with the induction of epigenetic changes and the formation of complexes containing RNA interference and chromatin-remodelling factors. Here, we show that a promoter-targeted siRNA inhibits transcription of the c-myc gene. Transcriptional silencing of c-myc did not involve changes of known epigenetic marks. Instead, the c-myc promoter-targeted siRNA interfered with transcription initiation blocking the assembly of the pre-initiation complex. Transcriptional interference depended on Argonaute 2 and a noncoding promoter-associated RNA initiated upstream and overlapping the transcription start site. Silencing of c-myc led to growth arrest, reduced clonogenic potential and senescence of c-myc over-expressing prostate cancer cells with minimal effect on normal cells. RNA-directed transcriptional interference may be a natural mechanism of transcriptional control and siRNAs targeting noncoding RNAs participating in this regulatory pathway could be valuable tools to control expression of deregulated genes in human diseases.

Cancer stem cells (CSC) play a significant role in tumor progression, disease recurrence, and treatment failure. Here, we show that the endogenously expressed ETS transcription factor ESE3/EHF controls prostate epithelial cell differentiation and stem-like potential. We found that loss of ESE3/EHF induced epithelial-to-mesenchymal transition (EMT), stem-like features, and tumor-initiating and metastatic properties in prostate epithelial cells, and reexpression of ESE3/EHF inhibited the stem-like properties and tumorigenic potential of prostate cancer cells. Mechanistically, ESE3/EHF repressed the expression of key EMT and CSC genes, including TWIST1, ZEB2, BMI1, and POU5F1. Analysis of human tissue microarrays showed that reduced ESE3/EHF expression is an early event in tumorigenesis, frequently occurring independently of other ETS gene alterations. Additional analyses linked loss of ESE3/EHF expression to a distinct group of prostate tumors with distinctive molecular and biologic characteristics, including increased expression of EMT and CSC genes. Low ESE3/EHF expression was also associated with increased biochemical recurrence of prostate cancer and reduced overall survival after prostatectomy. Collectively, our findings define a key role for ESE3/EHF in the development of a subset of prostate tumors and highlight the clinical importance of identifying molecularly defined tumor subgroups. Cancer Res; 72(11); 2889-900. Ó2012 AACR.

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BackgroundETS transcription factors regulate important signaling pathways involved in cell differentiation and development in many tissues and have emerged as important players in prostate cancer. However, the biological impact of ETS factors in prostate tumorigenesis is still debated.Methodology/Principal FindingsWe performed an analysis of the ETS gene family using microarray data and real-time PCR in normal and tumor tissues along with functional studies in normal and cancer cell lines to understand the impact in prostate tumorigenesis and identify key targets of these transcription factors. We found frequent dysregulation of ETS genes with oncogenic (i.e., ERG and ESE1) and tumor suppressor (i.e., ESE3) properties in prostate tumors compared to normal prostate. Tumor subgroups (i.e., ERGhigh, ESE1high, ESE3low and NoETS tumors) were identified on the basis of their ETS expression status and showed distinct transcriptional and biological features. ERGhigh and ESE3low tumors had the most robust gene signatures with both distinct and overlapping features. Integrating genomic data with functional studies in multiple cell lines, we demonstrated that ERG and ESE3 controlled in opposite direction transcription of the Polycomb Group protein EZH2, a key gene in development, differentiation, stem cell biology and tumorigenesis. We further demonstrated that the prostate-specific tumor suppressor gene Nkx3.1 was controlled by ERG and ESE3 both directly and through induction of EZH2.Conclusions/SignificanceThese findings provide new insights into the role of the ETS transcriptional network in prostate tumorigenesis and uncover previously unrecognized links between aberrant expression of ETS factors, deregulation of epigenetic effectors and silencing of tumor suppressor genes. The link between aberrant ETS activity and epigenetic gene silencing may be relevant for the clinical management of prostate cancer and design of new therapeutic strategies.

The aureolic acid antibiotic mithramycin (MTM) binds selectively to GC-rich DNA sequences and blocks preferentially binding of proteins, like Sp1 transcription factors, to GC-rich elements in gene promoters. Genetic approaches can be applied to alter the MTM biosynthetic pathway in the producing microorganism and obtain new products with improved pharmacological properties. Here, we report on a new analog, MTM SDK, obtained by targeted gene inactivation of the ketoreductase MtmW catalyzing the last step in MTM biosynthesis. SDK exhibited greater activity as transcriptional inhibitor compared to MTM. SDK was a potent inhibitor of Sp1-dependent reporter activity and interfered minimally with reporters of other transcription factors, indicating that it retained a high degree of selectivity toward GC-rich DNA-binding transcription factors. RT–PCR and microarray analysis showed that SDK repressed transcription of multiple genes implicated in critical aspects of cancer development and progression, including cell cycle, apoptosis, migration, invasion and angiogenesis, consistent with the pleiotropic role of Sp1 family transcription factors. SDK inhibited proliferation and was a potent inducer of apoptosis in ovarian cancer cells while it had minimal effects on viability of normal cells. The new MTM derivative SDK could be an effective agent for treatment of cancer and other diseases with abnormal expression or activity of GC-rich DNA-binding transcription factors.

Epigenetic silencing of tumour suppressor genes is an important mechanism involved in cell transformation and tumour progression. The Set and RING-finger-associated domain-containing protein UHRF1 might be an important link between different epigenetic pathways. Here, we report that UHRF1 is frequently overexpressed in human prostate tumours and has an important role in prostate cancer pathogenesis and progression. Analysis of human prostate cancer samples by microarrays and immunohistochemistry showed increased expression of UHRF1 in about half of the cases. Moreover, UHRF1 expression was associated with reduced overall survival after prostatectomy in patients with organ-confined prostate tumours (Po0.0001). UHRF1 expression was negatively correlated with several tumour suppressor genes and positively with the histone methyltransferase (HMT) EZH2 both in prostate tumours and cell lines. UHRF1 knockdown reduced proliferation, clonogenic capability and anchorage-independent growth of prostate cancer cells. Depletion of UHRF1 resulted in reactivation of several tumour suppressor genes. Gene reactivation upon UHRF1 depletion was associated with changes in histone H3K9 methylation, acetylation and DNA methylation, and impaired binding of the H3K9 HMT Suv39H1 to the promoter of silenced genes. Co-immunoprecipitation experiments showed direct interaction between UHRF1 and Suv39H1. Our data support the notion that UHRF1, along with Suv39H1 and DNA methyltransferases, contributes to epigenetic gene silencing in prostate tumours. This could represent a parallel and convergent pathway to the H3K27 methylation catalyzed by EZH2 to synergistically promote inactivation of tumour suppressor genes. Deregulated expression of UHRF1 is involved in the prostate cancer pathogenesis and might represent a useful marker to distinguish indolent cancer from those at high risk of lethal progression.

Deregulated expression of ETS transcription factors has emerged as an important event in prostate cancer pathogenesis. Here we show that the expression of epithelial-specific ETS (ESE)-3 factor is frequently reduced at the RNA and protein level in prostate cancer clinical samples compared to normal prostate. In PC3 and DU145 cells, ESE-3 was silenced by methylation of an evolutionarily conserved CpG site in its promoter and treatment with 5-aza-2 0 -deoxycytidine restored its expression. In a prostate epithelial cell transformation model, methylation of this site was inversely correlated with ESE-3 expression and occurred only in Ras-transformed and tumorigenic cells and not in normal and immortalized cells suggesting that ESE-3 silencing was functionally linked to oncogenic transformation. Consistent with a tumor suppressor function, re-expression of ESE-3 in prostate cancer cells inhibited clonogenic survival and induced apoptotic cell death. ESE-3 increased the level of procaspase-3, a key element in the apoptotic cascade. This effect was mediated at the transcriptional level by direct binding of ESE-3 to the caspase-3 promoter. Collectively, our findings implicate ESE-3 as a candidate tumor suppressor in prostate cancer. Decreased expression of ESE-3 may result in loss of important regulatory mechanisms in prostate epithelial cells and contribute to the pathogenesis of prostate cancer.