TSAP6 is a novel candidate marker of poor survival in metastatic high-grade serous carcinoma

Comprehensive Landscape of STEAP Family Members Expression in Human Cancers: Unraveling the Potential Usefulness in Clinical Practice Using Integrated Bioinformatics Analysis

The human Six-Transmembrane Epithelial Antigen of the Prostate (STEAP) family comprises STEAP1-4. Several studies have pointed out STEAP proteins as putative biomarkers, as well as therapeutic targets in several types of human cancers, particularly in prostate cancer. However, the relationships and significance of the expression pattern of STEAP1-4 in cancer cases are barely known. Herein, the Oncomine database and cBioPortal platform were selected to predict the differential expression levels of STEAP members and clinical prognosis. The most common expression pattern observed was the combination of the over- and underexpression of distinct STEAP genes, but cervical and gastric cancer and lymphoma showed overexpression of all STEAP genes. It was also found that STEAP genes’ expression levels were already deregulated in benign lesions. Regarding the prognostic value, it was found that STEAP1 (prostate), STEAP2 (brain and central nervous system), STEAP3 (kidney, leukemia and testicular) and STEAP4 (bladder, cervical, gastric) overexpression correlate with lower patient survival rate. However, in prostate cancer, overexpression of the STEAP4 gene was correlated with a higher survival rate. Overall, this study first showed that the expression levels of STEAP genes are highly variable in human cancers, which may be related to different patients’ outcomes.

Sialyl-Tn antigen facilitates extracellular vesicle-mediated transfer of FAK and enhances motility of recipient cells

Protein glycosylation plays a pivotal role in tumor development by modulating molecular interactions and cellular signals. Sialyl-Tn (sTn) antigen is a tumor associating carbohydrate epitope whose expression correlates with metastasis and poor prognosis of various cancers; however, its pathophysiological function is poorly understood. Extracellular vesicles (EVs) derived from cancer cells act as a signal mediator among tumor microenvironments by transferring cargo molecules. sTn antigen has been found in the glycans of EVs, thereby the functional relevance of sTn antigen to the regulation of tumor microenvironments could be expected. In the present study, we showed that sTn antigen induced TP53 and tumor suppressor activated pathway 6 (TSAP6), and consequently enhanced EV-production. Besides, the genetic attenuation of TSAP6 resulted in the reduction of the EV-production in the sTn antigen expressing cells. The enhanced EV-production in the sTn antigen expressing cells consequently augmented the delivery of EVs to recipient cells. The produced EVs selectively and abundantly encased focal adhesion kinase and transferred it to EV-recipient cells, and thus their cellular motility was enhanced. These findings would contribute to facilitate the elucidation of the pathophysiological significance of the sTn antigen in the tumor microenvironments and tumor development.

STEAP3 promotes cancer cell proliferation by facilitating nuclear trafficking of EGFR to enhance RAC1-ERK-STAT3 signaling in hepatocellular carcinoma

STEAP3 (Six-transmembrane epithelial antigen of the prostate 3, TSAP6, dudulin-2) has been reported to be involved in tumor progression in human malignancies. Nevertheless, how it participates in the progression of human cancers, especially HCC, is still unknown. In the present study, we found that STEAP3 was aberrantly overexpressed in the nuclei of HCC cells. In a large cohort of clinical HCC tissues, high expression level of nuclear STEAP3 was positively associated with tumor differentiation and poor prognosis (p < 0.001), and it was an independent prognostic factor for HCC patients. In HCC cell lines, nuclear expression of STEAP3 significantly promoted HCC cells proliferation by promoting stemness phenotype and cell cycle progression via RAC1-ERK-STAT3 and RAC1-JNK-STAT6 signaling axes. Through upregulating the expression and nuclear trafficking of EGFR, STEAP3 participated in regulating EGFR-mediated STAT3 transactivity in a manner of positive feedback. In summary, our findings support that nuclear expression of STEAP3 plays a critical oncogenic role in the progression of HCC via modulation on EGFR and intracellular signaling, and it could be a candidate for prognostic marker and therapeutic target in HCC.

lncRNA STEAP3-AS1 Modulates Cell Cycle Progression via Affecting CDKN1C Expression through STEAP3 in Colon Cancer

Previous studies have reported that long noncoding RNAs (lncRNAs) have acted as new players during tumorigenesis. Metallothionein also plays an important role in tumor progression. It is mainly considered to be involved in the process of cell proliferation, oxidative stress, and multidrug resistance. However, the potential involvement of metallothionein-related lncRNAs in colon cancer remains poorly understood. In our study, we found that MT1M affected the expression of lncRNA STEAP3-AS1. STEAP3-AS1 is located in physical contiguity with STEAP3 and notably increased in colon cancer tissues and cell lines. STEAP3-AS1 expression was negatively associated with the expression of STEAP3. High levels of STEPA3-AS1 were associated with poor overall survival in colon cancer patients. In in vitro assays, STEAP3-AS1 knockdown could inhibit colon cancer cell proliferation and migration and arrest colon cancer cells at the G₀-G₁ phase. In tumorigenicity assays, STEAP3-AS1 knockdown could strongly inhibit tumor growth. Mechanistic investigations demonstrated that STEAP3-AS1 downregulation could increase the expression of cyclin-dependent kinase inhibitor 1C (CDKN1C) by STEAP3 upregulation. Overall, we identify the underlying role of MT1M-related lncRNA STEAP3-AS1 in colon cancer progression, which provides a novel strategy for colon cancer therapy.

Role of the Exosome Secretion Machinery in Ovarian Carcinoma: In Vitro and In Vivo Models

Objective. We recently reported on the expression and clinical role of molecules that mediate exosome secretion in high-grade serous carcinoma. In the present study, the biological role of these molecules was analyzed. Methods. OVCAR8 and ES-2 ovarian carcinoma cells were studied using a combination of CRISPR/Cas9 technology and two 3D in vitro models—spheroids emulating effusions and alginate scaffolds representing solid lesions. Isolation of exosomes was validated by electron microscopy. TSAP6, NSMASE2, RAB27A, and RAB27B mRNA and protein levels were analyzed using qRT-PCR and Western blotting, respectively. Tumor aggressiveness was studied in vitro using scratch assay, invasion assay, and matrix metalloproteinase (MMP) activity assay and in vivo using a mouse model. Results. In OVCAR8 cells, mRNA expression of TSAP6 and RAB27A was significantly higher in spheroids compared to scaffolds, whereas the opposite was true for NSMASE2 mRNA. In ES-2 cells, TSAP6 and RAB27B mRNA expression was significantly higher in spheroids versus scaffolds. In addition, nSMase2 and TSAP6 protein expression was significantly higher in scaffolds compared to spheroids. CRISPR-edited cells with silencing of NSMASE2, TSAP6, and RAB27A/B had reduced migration, invasion, and MMP activity. Additionally, knockout (KO) of these molecules resulted in significantly diminished exosome secretion. In vivo assay showed that when injected to mice, OVCAR8 RAB27A/B KO cells, as opposed to control OVCAR8 cells, did not form ascites or visible tumor lesions and had reduced MMP expression. Conclusion. The present study provides evidence that different models for culturing ovarian carcinoma cells affect the expression of molecules mediating exosome secretion and that these molecules have a tumor-promoting role. Silencing these molecules may consequently have therapeutic relevance in this cancer.

Molecular testing on serous effusions

Serous effusions constitute a significant part of the material processed and diagnosed by cytopathology laboratories. Effusions may occur in a variety of clinical settings and the differential diagnosis between these conditions often requires ancillary tests. Immunohistochemistry is still the most frequently used method in this context. However, a wide array of other methods measuring the expression of DNA, mRNA, noncoding RNA, proteins, and other compounds may be applied to the diagnosis of serous effusions, particularly in the setting of cancer, as well as to studies focusing on tumor biology and understanding of tumor progression. In addition, as serous effusions provide ideal material for molecular testing, they have in recent years assumed central role as specimens informative of prediction in the context of targeted therapy, as well as prognostication. This review discusses recent studies in this field.

Hepatocyte-derived exosomal MiR-194 activates PMVECs and promotes angiogenesis in hepatopulmonary syndrome

Hepatopulmonary syndrome (HPS) is a serious vascular complication in the setting of liver disease. Factors produced by the liver are essential to regulate pulmonary angiogenesis in the pathogenesis of HPS; however, the pathogenic mechanisms of pulmonary angiogenesis are not fully understood. We investigated the role of HPS rat serum exosomes (HEs) and sham-operated rat serum exosomes (SEs) in the regulation of angiogenesis. We found that HEs significantly enhance PMVEC proliferation, migration, and tube formation. We further identified miR-194 was the most notably increased miRNA in HEs compared to SEs. Once released, hepatocyte-derived exosomal miR-194 was internalized by PMVECs, leading to the promotion of PMVEC proliferation, migration, and tube formation through direct targeting of THBS1, STAT1, and LIF. Importantly, the pathogenic role of exosomal miR-194 in initiating angiogenesis was reversed by P53 inhibition, exosome secretion inhibition or miR-194 inhibition. Additionally, high levels of miR-194 were found in serum exosomes and were positively correlated with P(A-a)O₂ in HPS patients and rats. Thus, our results highlight that the exosome/miR-194 axis plays a critical pathologic role in pulmonary angiogenesis, representing a new therapeutic target for HPS.

Soluble AXL is ubiquitously present in malignant serous effusions

OBJECTIVE

The objective of this study was to analyze the expression level and clinical role of soluble AXL (sAXL) in cancers affecting the serosal surfaces, with focus on ovarian carcinoma.

METHODS

sAXL protein expression by ELISA was analyzed in 572 effusion supernatants, including 424 peritoneal, 147 pleural and 1 pericardial specimens.

RESULTS

sAXL was overexpressed in peritoneal effusions compared to pleural and pericardial specimens (p < 0.001). sAXL levels were additionally significantly higher in effusions from patients with ovarian carcinoma, malignant mesothelioma and breast carcinoma compared to specimens from patients with other cancers (predominantly carcinomas of lung, gastrointestinal or uterine corpus/cervix origin) or benign reactive effusions (p < 0.001). sAXL was further overexpressed in high-grade serous carcinoma (HGSC; n = 373) compared to low-grade serous carcinoma (LGSC; n = 32; p = 0.036). In HGSC, sAXL levels were significantly lower in post-chemotherapy effusions compared to primary diagnosis pre-chemotherapy specimens (p = 0.002). sAXL levels in HGSC were unrelated to chemoresponse at diagnosis, progression-free survival or overall survival. Levels were similarly unrelated to survival in LGSC and breast carcinoma.

CONCLUSIONS

sAXL is widely expressed in malignant effusions, particularly in ovarian and breast carcinoma and in malignant mesothelioma. sAXL is overexpressed in HGSC compared to LGSC and its levels are lower following exposure to chemotherapy. However, sAXL levels are not informative of chemoresponse or survival.

Extracellular vesicles in the tumor microenvironment: Therapeutic resistance, clinical biomarkers, and targeting strategies

Numerous studies have proved that cell-nonautonomous regulation of neoplastic cells is a distinctive and essential characteristic of tumorigenesis. Two way communications between the tumor and the stroma, or within the tumor significantly influence disease progression and modify treatment responses. In the tumor microenvironment (TME), malignant cells utilize paracrine signaling initiated by adjacent stromal cells to acquire resistance against multiple types of anticancer therapies, wherein extracellular vesicles (EVs) substantially promote such events. EVs are nanoscaled particles enclosed by phospholipid bilayers, and can mediate intercellular communications between cancerous cells and the adjacent microenvironment to accelerate pathological proceeding. Here we review the most recent studies of EV biology and focus on key cell lineages of the TME and their EV cargoes that are biologically active and responsible for cancer resistance, including proteins, RNAs, and other potentially essential components. Since EVs are emerging as novel but critical elements in establishing and maintaining hallmarks of human cancer, timely and insightful understanding of their molecular properties and functional mechanisms would pave the road for clinical diagnosis, prognosis, and effective targeting in the global landscape of precision medicine. Further, we address the potential of EVs as promising biomarkers in cancer clinics and summarize the technical improvements in EV preparation, analysis, and imaging. We highlight the practical issues that should be exercised with caution to guide the development of targeting agents and therapeutic methodologies to minimize cancer resistance driven by EVs, thereby allowing to effectively control the early steps of disease exacerbation.