PSP94, an upstream signaling mediator of prostasin found highly elevated in ovarian cancer

GPI-anchored serine proteases: essential roles in development, homeostasis, and disease

The glycosylphosphatidylinositol (GPI)-anchored serine proteases, prostasin and testisin, have essential roles in diverse physiological functions including development, reproduction, homeostasis and barrier function of epithelia, angiogenesis, coagulation, and fibrinolysis. Important functions in pathological conditions such as cancer, kidney disease and cardiovascular disease have also been reported. In this review, we summarize current knowledge of the cellular and in vivo roles of prostasin and testisin in physiology and pathophysiology and explore the underlying molecular mechanisms. We discuss how new insights of their role in cancer and cardiovascular disease may facilitate translation into clinical settings in the future.

The microRNA Let-7 and its exosomal form: Epigenetic regulators of gynecological cancers

Many types of gynecological cancer (GC) are often silent until they reach an advanced stage, and are therefore often diagnosed too late for effective treatment. Hence, there is a real need for more efficient diagnosis and treatment for patients with GC. During recent years, researchers have increasingly studied the impact of microRNAs cancer development, leading to a number of applications in detection and treatment. MicroRNAs are a particular group of tiny RNA molecules that regulate regular gene expression by affecting the translation process. The downregulation of numerous miRNAs has been observed in human malignancies. Let-7 is an example of a miRNA that controls cellular processes as well as signaling cascades to affect post-transcriptional gene expression. Recent research supports the hypothesis that enhancing let-7 expression in those cancers where it is downregulated may be a potential treatment option. Exosomes are tiny vesicles that move through body fluids and can include components like miRNAs (including let-7) that are important for communication between cells. Studies proved that exosomes are able to enhance tumor growth, angiogenesis, chemoresistance, metastasis, and immune evasion, thus suggesting their importance in GC management.

Peptidase inhibitor 16 promotes proliferation of pancreatic ductal adenocarcinoma cells through OASL signaling

Pancreatic ductal adenocarcinoma (PDAC) is a highly invasive cancer with a poor prognosis and a 5-year survival rate of less than 11%. As a member of the CAP superfamily of proteins, the role of peptidase inhibitor 16 (Pi16) in tumor progression is still unclear. Immunohistochemistry and quantitative RT-PCR methods were used to detect the expression levels of Pi16 protein and mRNA in PDAC patients. CRISPR/Cas9 technology was used to knock out the expression of Pi16 in PDAC cell lines. In vivo and in vitro experiments were used to verify the effect of Pi16 on PDAC proliferation ability. By RNA sequencing, we found that oligoadenylate synthetase L (OASL) can serve as a potential downstream target of Pi16. The expression of Pi16 was higher in PDAC tissues than in matched adjacent tissues. High expression of Pi16 was associated with PDAC progression and poor prognosis. Overexpression of Pi16 could promote the proliferation of PDAC cells in vitro and in vivo. Bioinformatics analysis and coimmunoprecipitation assays showed that Pi16 could bind to OASL. Moreover, the functional recovery test confirmed that Pi16 could promote the proliferation of PDAC via OASL. Our present study demonstrates that Pi16 might participate in the occurrence and development of PDAC by regulating cell proliferation by binding to OASL, indicating that Pi16 might be a promising novel therapeutic target for PDAC.

Peptidase inhibitor (PI16) impairs bladder cancer metastasis by inhibiting NF-κB activation via disrupting multiple-site ubiquitination of NEMO

BACKGROUND

Bladder cancer (BLCA) is a malignancy that frequently metastasizes and leads to poor patient prognosis. It is essential to understand the molecular mechanisms underlying the progression and metastasis of BLCA and identify potential biomarkers.

METHODS

The expression of peptidase inhibitor 16 (PI16) was analysed using quantitative PCR, immunoblotting and immunohistochemistry assays. The functional roles of PI16 were evaluated using wound healing, transwell, and human umbilical vein endothelial cell tube formation assays, as well as in vivo tumour models. The effects of PI16 on nuclear factor κB (NF-κB) signalling activation were examined using luciferase reporter gene systems, immunoblotting and immunofluorescence assays. Co-immunoprecipitation was used to investigate the interaction of PI16 with annexin-A1 (ANXA1) and NEMO.

RESULTS

PI16 expression was downregulated in bladder cancer tissues, and lower PI16 levels correlated with disease progression and poor survival in patients with BLCA. Overexpressing PI16 inhibited BLCA cell growth, motility, invasion and angiogenesis in vitro and in vivo, while silencing PI16 had the opposite effects. Mechanistically, PI16 inhibited the activation of the NF-κB pathway by interacting with ANXA1, which inhibited K63 and M1 ubiquitination of NEMO.

CONCLUSIONS

These results indicate that PI16 functions as a tumour suppressor in BLCA by inhibiting tumour growth and metastasis. Additionally, PI16 may serve as a potential biomarker for metastatic BLCA.

LIN28B promotes the development of neuroendocrine prostate cancer

Therapy-induced neuroendocrine prostate cancer (t-NEPC) is a highly aggressive subtype of prostate cancer with poor patient survival. Emerging evidence indicates that t-NEPC can develop when prostate adenocarcinoma cells acquire cancer stem-like cell signaling in the presence of androgen receptor inhibition, followed by redifferentiation toward neuroendocrine lineage and subsequent t-NEPC progression. Whether the stem-like signaling is controlled by the core pluripotency stem cell genes (e.g., LIN28 and SOX2) remains unknown. Here, we report that the transcription of the LIN28B isoform and SOX2 were co-upregulated in t-NEPC patient tumors, patient-derived xenografts, transgenic mice, and cell models. Immunohistochemistry validated that LIN28B and SOX2 protein expression were elevated in t-NEPC patient biopsies. Using prostate adenocarcinoma and t-NEPC cell models, we demonstrated that LIN28B induced a stem-like gene network, neuroendocrine biomarkers, and neuroendocrine cell morphology. LIN28B depletion by CRISPR inhibited t-NEPC tumorigenesis and xenograft growth. These LIN28B functions were mediated mainly through the suppression of let-7 miRNA expression, resulting in de-repression of the transcription factor HMGA2 and HMGA2-mediated SOX2 expression. This study revealed a mechanism by which t-NEPC can develop through the LIN28B/let-7/SOX2 axis that regulates a cancer cell stem-like gene network, highlighting LIN28B as a potential therapeutic target in t-NEPC.

RNA-Seq analysis on ets1 mutant embryos of Xenopus tropicalis identifies microseminoprotein beta gene 3 as an essential regulator of neural crest migration

The proto-oncogene ets1 is highly expressed in the pre-migratory and migratory neural crest (NC), and has been implicated in the delamination and migration of the NC cells. To identify the downstream target genes of Ets1 in this process, we did RNA sequencing (RNA-Seq) on wild-type and ets1 mutant X. tropicalis embryos. A list of genes with significantly differential expression was obtained by analyzing the RNA-Seq data. We validated the RNA-Seq data by quantitative PCR, and examined the expression pattern of the genes identified from this assay with whole mount in situ hybridization. A majority of the identified genes showed expression in migrating NC. Among them, the expression of microseminoprotein beta gene 3 (msmb3) was positively regulated by Ets1 in both X. laevis and X. tropicalis. Knockdown of msmb3 with antisense morpholino oligonucleotides or disruption of msmb3 by CRISPR/Cas9 both impaired the migratory streams of NC. Our study identified msmb3 as an Ets1 target gene and uncovered its function in maintaining neural crest migration pattern.

Prostate-specific markers to identify rare prostate cancer cells in liquid biopsies

Despite improvements in early detection and advances in treatment, patients with prostate cancer continue to die from their disease. Minimal residual disease after primary definitive treatment can lead to relapse and distant metastases, and increasing evidence suggests that circulating tumour cells (CTCs) and bone marrow-derived disseminated tumour cells (BM-DTCs) can offer clinically relevant biological insights into prostate cancer dissemination and metastasis. Using epithelial markers to accurately detect CTCs and BM-DTCs is associated with difficulties, and prostate-specific markers are needed for the detection of these cells using rare cell assays. Putative prostate-specific markers have been identified, and an optimized strategy for staining rare cancer cells from liquid biopsies using these markers is required. The ideal prostate-specific marker will be expressed on every CTC or BM-DTC throughout disease progression (giving high sensitivity) and will not be expressed on non-prostate-cancer cells in the sample (giving high specificity). Some markers might not be specific enough to the prostate to be used as individual markers of prostate cancer cells, whereas others could be truly prostate-specific and would make ideal markers for use in rare cell assays. The goal of future studies is to use sensitive and specific prostate markers to consistently and reliably identify rare cancer cells.

Crystal structure of the complex between venom toxin and serum inhibitor from Viperidae snake

Venomous snakes have endogenous proteins that neutralize the toxicity of their venom components. We previously identified five small serum proteins (SSP-1-SSP-5) from a highly venomous snake belonging to the family Viperidae as inhibitors of various toxins from snake venom. The endogenous inhibitors belong to the prostate secretory protein of 94 amino acids (PSP94) family. SSP-2 interacts with triflin, which is a member of the cysteine-rich secretory protein (CRISP) family that blocks smooth muscle contraction. However, the structural basis for the interaction and the biological roles of these inhibitors are largely unknown. Here, we determined the crystal structure of the SSP-2-triflin complex at 2.3 Å resolution. A concave region centrally located in the N-terminal domain of triflin is fully occupied by the terminal β-strands of SSP-2. SSP-2 does not bind tightly to the C-terminal cysteine-rich domain of triflin; this domain is thought to be responsible for its channel-blocker function. Instead, the cysteine-rich domain is tilted 7.7° upon binding to SSP-2, and the inhibitor appears to sterically hinder triflin binding to calcium channels. These results help explain how an endogenous inhibitor prevents the venomous protein from maintaining homeostasis in the host. Furthermore, this interaction also sheds light on the binding interface between the human homologues PSP94 and CRISP-3, which are up-regulated in prostate and ovarian cancers.

Loss of PSP94 expression is associated with early PSA recurrence and deteriorates outcome of PTEN deleted prostate cancers

Objective

Prostate secretory protein of 94 amino acids (PSP94) is a target gene of the EZH2 transcriptional repressor and is often downregulated in prostate cancer; however, its prognostic value is disputed.

Methods

Immunohistochemical analysis of a tissue microarray of 12, 432 prostate cancer specimens was performed to evaluate PSP94 expression. Correlation of PSP94 expression with tumor phenotype, patient prognosis, TMPRSS2:ERG fusion status, EZH2 expression and PTEN deletion was studied.

Results

PSP94 expression was increased in benign prostatic hyperplasia; however, it was downregulated in 48% and negative in 42% of the 9, 881 interpretable prostate cancer specimens. The loss of PSP94 expression was inversely correlated to EZH2 expression (P < 0.0001) and largely unrelated to the ERG status, but strongly correlated with high Gleason grade, advanced tumor stage, and nodal metastasis ( P <0.0001 each). The fraction of PSP94-negative cancer specimens increased from 40% in pT2 to 52% in pT3b-pT4 ( P < 0.0001) and from 40% in Gleason 3+3 = 6 to 46% in Gleason 4+3 = 7 and 60% in Gleason ≥4+4 = 8 ( P < 0.0001). Loss of PSP94 was linked to early prostate-specific antigen recurrence, but with little absolute effect ( P < 0.0001). However, it provided additional prognostic impact in cancer specimens with PTEN deletion. Loss of PSP94 deteriorated prognosis of cancer patients with PTEN deletion by more than 10% (P < 0.0001). The combination of PTEN deletion and PSP94 loss provided independent prognostic information that was observed in several subgroups defined by classical and quantitative Gleason grade.

Conclusions

The results of our study suggest that combined PSP94/PTEN analysis can be potentially used in the clinical prognosis of prostate cancer.