Probes for PTEN

The emergence of castration resistant prostate cancer is associated with a high mortality and remains an area of unmet clinical need. We recently identified a rare subpopulation of normal prostate progenitor cells, characterized by an intrinsic resistance to androgen-deprivation and marked by the expression of LY6D. We here describe the underlying mechanisms driving castration-resistance of LY6D+ luminal progenitors and their contribution to advanced prostate cancer. We demonstrate that conditional deletion of PTEN in the murine prostate epithelium causes an expansion of transformed LY6D+ progenitor cells in proximal and distal regions of the prostate without impairing stem cell properties. Transcriptomic analyses of LY6D+  luminal cells identified an autocrine positive feed-back loop, based on the secretion of amphiregulin (AREG), further increasing cellular fitness and organoid formation. Pharmacological interference with AREG-activated MAPK-signaling overcomes the castration-resistant properties of LY6D+ cells with a near complete suppression of organoid formation. Notably, LY6D+  tumor cells are enriched in prostate specimens from high-grade and androgen-resistant prostate cancer, providing clinical evidence for their contribution to advanced and also metastatic disease. Our data indicate that the prospective identification of LY6D+ cells could allow for an early interference with MAPK-inhibitors to prevent the emergence of castration-resistant prostate cancer.

Primary female urethral carcinoma (PUC-F) accounts for less than 1% of all genitourinary malignancies and comprises a histologically diverse group of tumors that are usually associated with poor prognosis. The carcinomas documented at this site include adenocarcinoma (clear cell adenocarcinoma, columnar cell carcinoma, and Skene gland adenocarcinoma), urothelial carcinoma (UCa), and squamous cell carcinoma (SCC). Recent studies have shown adenocarcinomas to be the most common type of primary urethral carcinoma in females. As most of the urethral carcinomas morphologically resemble carcinomas arising from surrounding pelvic organs or metastases, these should be ruled out before making the diagnosis of PUC-F. These tumors are currently staged according to the 8th edition of the American Joint Committee on Cancer (AJCC) staging system. However, the AJCC system has limitations, including the staging of tumors involving the anterior wall of the urethra. Staging systems like the recently proposed histology-based female urethral carcinoma staging system (UCS) takes into account the unique histological landmarks of the female urethra to better stratify pT2 and pT3 tumors into prognostic groups, that correlate with clinical outcomes including recurrence rates, disease-specific survival and overall survival. Further larger multi-institutional cohorts are however required to validate the results of this staging system. There is very limited information regarding the molecular profiling of PUC-F. Thirty-one percent of clear cell adenocarcinomas have been reported to show PIK3CA alterations, whereas 15% of adenocarcinomas show PTEN mutations. Higher tumor mutational burden and PD-L1 staining have been reported in UCa and SCC. Although multimodality treatment is usually recommended in locally advanced and metastatic disease, the role of immunotherapy and targeted therapy is promising in select PUC-F cases.

The corticospinal tract (CST) is clinically important for the recovery of motor functions after spinal cord injury. Despite substantial progress in understanding the biology of axon regeneration in the central nervous system (CNS), our ability to promote CST regeneration remains limited. Even with molecular interventions, only a small proportion of CST axons regenerate1. Here we investigate this heterogeneity in the regenerative ability of corticospinal neurons following PTEN and SOCS3 deletion with patch-based single cell RNA sequencing (scRNA-Seq)2,3, which enables deep sequencing of rare regenerating neurons. Bioinformatic analyses highlighted the importance of antioxidant response and mitochondrial biogenesis along with protein translation. Conditional gene deletion validated a role for NFE2L2 (or NRF2), a master regulator of antioxidant response, in CST regeneration. Applying Garnett4, a supervised classification method, to our dataset gave rise to a Regenerating Classifier (RC), which, when applied to published scRNA-Seq data, generates cell type- and developmental stage-appropriate classifications. While embryonic brain, adult dorsal root ganglion and serotonergic neurons are classified as Regenerators, most neurons from adult brain and spinal cord are classified as Non-regenerators. Adult CNS neurons partially revert to a regenerative state soon after injury, which is accelerated by molecular interventions. Our data indicate the existence of universal transcriptomic signatures underlying the regenerative abilities of vastly different neuronal populations, and further illustrate that deep sequencing of only hundreds of phenotypically identified CST neurons has the power to reveal new insights into their regenerative biology.

Primary female urethral carcinoma (PUC-F) accounts for less than 1% of all genitourinary malignancies and comprises a histologically diverse group of tumors that are usually associated with poor prognosis. The carcinomas documented at this site include adenocarcinoma (clear cell adenocarcinoma, columnar cell carcinoma and Skene gland adenocarcinoma), urothelial carcinoma (UCa) and squamous cell carcinoma (SCC). Recent studies have shown adenocarcinomas to be the most common type of primary urethral carcinoma in females. Since most of the urethral carcinomas morphologically resemble carcinomas arising from surrounding pelvic organs or metastases, these should be ruled out before making the diagnosis of PUC-F. These tumors are currently staged according to the 8th edition of the American Joint Committee on Cancer (AJCC) staging system. However, the AJCC system has limitations, including the staging of tumors involving the anterior wall of the urethra. Staging systems like the recently proposed histology based female urethral carcinoma staging system (UCS) takes into account the unique histological landmarks of the female urethra to better stratify pT2 and pT3 tumors into prognostic groups, that correlate with clinical outcomes including recurrence rates, disease-specific and overall survival. Further larger multi-institutional cohorts are however required to validate the results of this staging system. There is very limited information regarding the molecular profiling of PUC-F. 31% of clear cell adenocarcinomas have been reported to show PIK3CA alterations, while 15% of adenocarcinomas show PTEN mutations. Higher tumor mutational burden (TMB) and PD-L1 staining have been reported in UCa and SCC. Although multimodality treatment is usually recommended in locally advanced and metastatic disease, the role of immunotherapy and targeted therapy is promising in select PUC-F cases.

Peribiliary glands (PBGs), clusters of epithelial cells residing in the submucosal compartment of extrahepatic bile ducts, have been suggested as biliary epithelial stem/progenitor cell niche; however, evidence to support this claim is limited due to a lack of PBG-specific markers. We therefore sought to identify PBG-specific markers to investigate the potential role of PBGs as stem/progenitor cell niches, as well as an origin of cancer. We examined the expression pattern of the Wnt target gene Axin2 in extrahepatic bile ducts. We then applied lineage tracing to investigate whether Axin2-expressing cells from PBGs contribute to biliary regeneration and carcinogenesis using Axin2-CreERT mice. Wnt signaling activation, marked by Axin2, was limited to PBGs located in the periampullary region. Lineage tracing revealed that Axin2-expressing periampullary PBG cells are capable of self-renewal and supplying new biliary epithelial cells (BECs) to the luminal surface. Additionally, the expression pattern of Axin2 and the mature ductal cell marker CK19 was mutually exclusive in periampullary region, and fate tracing of CK19+ luminal surface BECs revealed gradual replacement by CK19- cells, further supporting the continuous replenishment of new BECs from PBGs to the luminal surface. We also found that Wnt signal enhancer R-spondin3 secreted from Myh11-expressing stromal cells, corresponding to human sphincter of Oddi, maintained the periampullary Wnt signal-activating niche. Notably, introduction of PTEN deletion into Axin2+ PBG cells, but not CK19+ luminal surface BECs, induced ampullary carcinoma whose development was suppressed by Wnt inhibitor. A specific cell population receiving Wnt-activating signal in periampullary PBGs functions as biliary epithelial stem/progenitor cells and also cellular origin of ampullary carcinoma.

Glycine transporters (GlyT1 and GlyT2) that regulate levels of brain glycine, an inhibitory neurotransmitter with co-agonist activity for NMDA receptors (NMDARs), have been considered to be important targets for the treatment of brain disorders with suppressed NMDAR function such as schizophrenia. However, it remains unclear whether other amino acid transporters expressed in the brain can also regulate brain glycine levels and NMDAR function. Here, we report that SLC6A20A, an amino acid transporter known to transport proline based on in vitro data but is understudied in the brain, regulates proline and glycine levels and NMDAR function in the mouse brain. SLC6A20A transcript and protein levels were abnormally increased in mice carrying a mutant PTEN protein lacking the C terminus through enhanced β-catenin binding to the Slc6a20a gene. These mice displayed reduced extracellular levels of brain proline and glycine and decreased NMDAR currents. Elevating glycine levels back to normal ranges by antisense oligonucleotide-induced SLC6A20 knockdown, or the competitive GlyT1 antagonist sarcosine, normalized NMDAR currents and repetitive climbing behavior observed in these mice. Conversely, mice lacking SLC6A20A displayed increased extracellular glycine levels and NMDAR currents. Lastly, both mouse and human SLC6A20 proteins mediated proline and glycine transports, and SLC6A20 proteins could be detected in human neurons. These results suggest that SLC6A20 regulates proline and glycine homeostasis in the brain and that SLC6A20 inhibition has therapeutic potential for brain disorders involving NMDAR hypofunction.

We have described a rare group of prostate adenocarcinomas that show aberrant expression of p63, a protein strongly expressed in prostatic basal cells and absent from usual-type acinar prostate cancers. The partial basal-like immunophenotype of these tumors is intriguing in light of the persistent debate surrounding the cell-of-origin for prostate cancer; however, their molecular phenotype is unknown. We collected 37 of these tumors on radical prostatectomy and biopsy and assessed subsets for a diverse panel of molecular markers. The majority of p63-expressing tumors were positive for the ΔNp63 isoform (6/7) by immunofluorescence and p63 mRNA (7/8) by chromogenic in situ hybridization. Despite p63 positivity, these tumors uniformly expressed luminal-type cytokeratin proteins such as CK18 (13/13), CK8 (8/8), and markers of androgen axis signaling commonly seen in luminal cells, including androgen receptor (10/11), NKX3.1 (8/8), and prostein (12/13). Conversely, basal cytokeratins such as CK14 and CK15 were negative in all cases (0/8) and CK5/6 was weakly and focally positive in 36% (4/11) of cases. Pluripotency markers including β-catenin, Oct4, and c-kit were negative in p63-expressing tumors (0/11). Despite nearly universal expression of androgen receptor and downstream androgen signaling targets, p63-expressing tumors lacked ERG rearrangements by fluorescence in situ hybridization (0/14) and ERG protein expression (0/37). No tumors expressed SPINK1 or showed PTEN protein loss (0/19). Surprisingly, 74% (14/19) of p63-expressing tumors expressed GSTP1 protein at least focally, and 33% (2/6) entirely lacked GSTP1 CpG island hypermethylation by bisulfite sequencing. In contrast to usual prostatic adenocarcinomas, prostate tumors with p63 expression show a mixed luminal/basal immunophenotype, uniformly lack ERG gene rearrangement, and frequently express GSTP1. These data strongly suggest that p63-expressing prostate tumors represent a molecularly distinct subclass and further study of this rare tumor type may yield important insights into the role of p63 in prostatic biology and the prostate cancer cell-of-origin.

Black men are two to three times more likely to die from prostate cancer (PCa) than White men. This disparity is due in part to discrepancies in socioeconomic status and access to quality care. Studies also suggest that differences in the prevalence of innate immune cells and heightened function in the tumor microenvironment of Black men may promote PCa aggressiveness.We evaluated the spatial localization of and quantified CD66ce+ neutrophils by immunohistochemistry and CD68+ (pan), CD80+ (M1), and CD163+ (M2) macrophages by RNA in situ hybridization on formalin-fixed paraffin-embedded tissues from organ donor "normal" prostate (n = 9) and radical prostatectomy (n = 38) tissues from Black and White men. Neutrophils were quantified in PCa and matched benign tissues in tissue microarray (TMA) sets comprised of 560 White and 371 Black men. Likewise, macrophages were quantified in TMA sets comprised of tissues from 60 White and 120 Black men. The phosphatase and tensin homolog (PTEN) and ETS transcription factor ERG (ERG) expression status of each TMA PCa case was assessed via immunohistochemistry. Finally, neutrophils and macrophage subsets were assessed in a TMA set comprised of distant metastatic PCa tissues collected at autopsy (n = 6) sampled across multiple sites.CD66ce+ neutrophils were minimal in normal prostates, but were increased in PCa compared to benign tissues, in low grade compared to higher grade PCa, in PCa tissues from White compared to Black men, and in PCa with PTEN loss or ERG positivity. CD163+ macrophages were the predominant macrophage subset in normal organ donor prostate tissues from both Black and White men and were significantly more abundant in organ donor compared to prostatectomy PCa tissues. CD68,+  CD80,+ and CD163+ macrophages were significantly increased in cancer compared to benign tissues and in cancers with ERG positivity. CD68+ and CD163+ macrophages were increased in higher grade cancers compared to low grade cancer and CD80 expression was significantly higher in benign prostatectomy tissues from Black compared to White men.Innate immune cell infiltration is increased in the prostate tumor microenvironment of both Black and White men, however the composition of innate immune cell infiltration may vary between races.