High SRPX2 protein expression predicts unfavorable clinical outcome in patients with prostate cancer

P, Danieli-Mackay A, Lenz C, Brockmeyer P, Gross JC. The Ceramide-Dependent EV Secretome Differentially Affects Prostate Cancer Cell Migration

Tumor-derived extracellular vesicles (EVs) play an important role in cancer progression. Neutral sphingomyelinases (nSMases) are lipid-modifying enzymes that modulate the secretion of EVs from cells. How nSMase activity and therefore ceramide generation affect the composition and functionality of secreted EVs is not fully understood. Here, we aimed to investigate the expression of nSMases 1 and 2 in prostate cancer (PCa) tissue and their role in EV composition and secretion for prostate cancer cell migration. Reduced nSMase 1 and 2 expression was found in prostate cancer and correlated with the age of the patient. When nSMase 2 was inhibited by GW4869 in PCa cells (PC3 and DU145), the EV secretome was significantly altered, while the number of EVs and the total protein content of released EVs were not significantly changed. Using proteomic analysis, we found that extracellular matrix proteins, such as SDC4 (Syndecan-4) and SRPX-2, were differentially secreted on EVs from GW4869-treated PC3 cells. In scratch wound migration assays, GW4869 significantly increased migration compared to control PC3 cells but not DU145 cells, while SDC4 knockdown significantly reduced the migration of PC3 cells. These and other nSMase-2-dependent secreted proteins are interesting candidates for understanding the role of stress-induced EVs in the progression of prostate cancer.

The oncogenic role of LGR6 overexpression induced by aberrant Wnt/β-catenin signaling in lung cancer

BACKGROUND

Molecular abnormalities in the Wnt/β-catenin pathway confer malignant phenotypes in lung cancer. Previously, we identified the association of leucine-rich repeat-containing G protein-coupled receptor 6 (LGR6) with oncogenic Wnt signaling, and its downregulation upon β-catenin knockdown in non-small cell lung cancer (NSCLC) cells carrying CTNNB1 mutations. The aim of this study was to explore the mechanisms underlying this association and the accompanying phenotypes.

METHODS

LGR6 expression in lung cancer cell lines and surgical specimens was analyzed using quantitative RT-PCR and immunohistochemistry. Cell growth was assessed using colony formation assay. Additionally, mRNA sequencing was performed to compare the expression profiles of cells subjected to different treatments.

RESULTS

LGR6 was overexpressed in small cell lung cancer (SCLC) and NSCLC cell lines, including the CTNNB1-mutated NSCLC cell lines HCC15 and A427. In both cell lines, LGR6 knockdown inhibited cell growth. LGR6 expression was upregulated in spheroids compared to adherent cultures of A427 cells, suggesting that LGR6 participates in the acquisition of cancer stem cell properties. Immunohistochemical analysis of lung cancer specimens revealed that the LGR6 protein was predominantly overexpressed in SCLCs, large cell neuroendocrine carcinomas, and lung adenocarcinomas, wherein LGR6 overexpression was associated with vascular invasion, the wild-type EGFR genotype, and an unfavorable prognosis. Integrated mRNA sequencing analysis of HCC15 and A427 cells with or without LGR6 knockdown revealed LGR6-related pathways and genes associated with cancer development and stemness properties.

CONCLUSIONS

Our findings highlight the oncogenic roles of LGR6 overexpression induced by aberrant Wnt/β-catenin signaling in lung cancer.

SRPX2 promotes cancer cell proliferation and migration of papillary thyroid cancer

Thyroid cancer is the endocrine tumor with the highest incidence at present. It originates from the thyroid follicular epithelium or follicular paraepithelial cells. There is an increasing incidence of thyroid cancer all over the world. We found that SRPX2 expression level was higher in papillary thyroid tumors than in normal thyroid tissues, and SRPX2 expression was closely related to tumor grade and clinical prognosis. Previous reports showed that SRPX2 could function by activating PI3K/AKT signaling pathway. In addition, in vitro experiments showed that SRPX2 promoted the proliferation and migration of papillary thyroid cancer (PTC). In conclusion, SRPX2 could promote the malignant development of PTC. This may be a potential treatment target for PTC.

Substance P is overexpressed in cervical squamous cell carcinoma and promoted proliferation and invasion of cervical cancer cells <em>in vitro</em>

This study aimed to investigate the expression and function of substance P in cervical squamous cell carcinoma. Cancer tissues and adjacent tissues of 20 patients with cervical squamous cell carcinoma in our hospital were collected. The expression of substance P was detected by immunohistochemistry and Western blot analysis. Cervical squamous cell carcinoma line SiHa was treated with different concentrations of substance P. The proliferation of SiHa cells was detected by EdU assay, and the invasion ability of SiHa cells was detected by transwell assay. The phosphorylation of ERK1/2 and the expression of MMP9 were detected by Western blot analysis. The results showed that substance P was expressed in the cytoplasm and some cell membranes of cervical squamous cell carcinoma cells. The expression of substance P in cervical cancer tissues was significantly higher than that in the adjacent tissues. Compared with the control group, substance P significantly promoted the proliferation and invasion of SiHa cells in a concentration dependent manner and activated the phosphorylation of ERK1/2 and upregulated the expression of MMP9 in SiHa cells. In conclusion, substance P is highly expressed in cervical squamous cell carcinoma and can promote cervical cancer cell proliferation and invasion. The mechanism is related to the activation of ERK1/2 pathway to upregulate MMP9.

Global hypo-methylation in a proportion of glioblastoma enriched for an astrocytic signature is associated with increased invasion and altered immune landscape

We describe a subset of glioblastoma, the most prevalent malignant adult brain tumour, harbouring a bias towards hypomethylation at defined differentially methylated regions. This epigenetic signature correlates with an enrichment for an astrocytic gene signature, which together with the identification of enriched predicted binding sites of transcription factors known to cause demethylation and to be involved in astrocytic/glial lineage specification, point to a shared ontogeny between these glioblastomas and astroglial progenitors. At functional level, increased invasiveness, at least in part mediated by SRPX2, and macrophage infiltration characterise this subset of glioblastoma.

SRPX2 Promotes Tumor Proliferation and Migration via the FAK Pathway in Papillary Thyroid Carcinoma

Thyroid cancer is the most common form of endocrine cancer around the world, and among which papillary thyroid carcinoma (PTC) is the most ubiquitous pathological sub-kind. Sushi repeat-containing protein X-linked 2 (SRPX2) was reported to be an independent prognostic factor and significantly overexpressed in advanced PTC patients. However, the biological functions of SRPX2 remain ambiguous in PTC. Here, we explored SRPX2 expression profiles and functions in PTC, finding that SRPX2 expression was remarkably upregulated in PTC tissues and cell lines. Further colony formation, CCK-8, as well as transwell assay, suggested that SRPX2 silencing remarkably dampened PTC growth and migration. Mouse xenograft models were established to find that SRPX2 silence remarkably suppressed PTC proliferation and migration in vivo. Following mechanism studies revealed that SRPX2 realized its functions in the PTC process partially through activating the Focal adhesion kinase (FAK) phosphorylation. In conclusion, this study investigated the functions and mechanisms of the SRPX2/FAK pathway in PTC progression. SRPX2 could act as a prospective biologic signature and therapeutic target molecule for PTC.

Sushi-Repeat-Containing Protein X-Linked 2: A Potential Therapeutic Target for Inflammation and Cancer Therapy

Accumulating evidence has showed that sushi-repeat-containing protein X-linked 2 (SRPX2) is an abnormal expression in a variety of cancers and involved in cancer carcinogenesis, chemosensitivity, and prognosis, which mainly promote cancer cell metastasis, invasion, and migration by regulating the uPAR/integrins/FAK signaling pathway, epithelial-mesenchymal transition (EMT), angiogenesis, and glycosylation. Inflammation has been regarded as a key role in regulating cancer initiation, progression, EMT, and therapeutics. Furthermore, SRPX2 exhibited excellent antifibrosis effect via the TGFβR1/SMAD3/SRPX2/AP1/SMAD7 signaling pathway. Therefore, this review provides compelling evidence that SRPX2 might be a therapeutic target for inflammation and cancer-related inflammation for future cancer therapeutics.

The Landscape of the Tumor Microenvironment in Skin Cutaneous Melanoma Reveals a Prognostic and Immunotherapeutically Relevant Gene Signature

The tumorigenesis of skin cutaneous melanoma (SKCM) remains unclear. The tumor microenvironment (TME) is well known to play a vital role in the onset and progression of SKCM. However, the dynamic mechanisms of immune regulation are insufficient. We conducted a comprehensive analysis of immune cell infiltration in the TME. Based on the differentially expressed genes (DEGs) in clusters grouped by immune infiltration status, a set of hub genes related to the clinical prognosis of SKCM and tumor immune infiltration was explored. Methods: We analyzed immune cell infiltration in two independent cohorts and assessed the relationship between the internal pattern of immune cell infiltration and SKCM characteristics, including clinicopathological features, potential biological pathways, and gene mutations. Genes related to the infiltration pattern of TME immune cells were determined. Furthermore, the unsupervised clustering method (k-means) was used to divide samples into three different categories according to TME, which were defined as TME cluster-A, -B, and -C. DEGs among three groups of samples were analyzed as signature genes. We further distinguished common DEGs between three groups of samples according to whether differences were significant and divided DEGs into the Signature gene-A group with significant differences and the Signature gene-B group with insignificant differences. The Signature gene-A gene set mainly had exon skipping in SKCM, while the Signature gene-B gene set had no obvious alternative splicing form. Subsequently, we analyzed genetic variations of the two signatures and constructed a competing endogenous RNA (ceRNA) regulatory network. LASSO Cox regression was used to determine the immune infiltration signature and risk score of SKCM. Finally, we obtained 13 hub genes and calculated the risk score based on the coefficient of each gene to explore the impact of the high- and low-risk scores on biologically related functions and prognosis of SKCM patients further. The correlation between the risk score and clinicopathological characteristics of SKCM patients indicated that a low-risk score was associated with TME cluster-A classification (p < 0.001) and metastatic SKCM (p < 0.001). Thirteen hub genes also showed different prognostic effects in pan-cancer. The results of univariate and multivariate Cox analyses revealed that risk score could be used as an independent risk factor for predicting the prognosis of SKCM patients. The nomogram that integrated clinicopathological characteristics and immune characteristics to predict survival probability was based on multivariate Cox regression. Finally, 13 hub genes that showed different prognostic effects in pan-cancers were obtained. According to immunohistochemistry staining results, Ube2L6, SRPX2, and IFIT2 were expressed at higher levels, while CLEC4E, END3, and KIR2DL4 were expressed at lower levels in 25 melanoma specimens. Conclusion: We performed a comprehensive assessment of the immune-associated TME. To elucidate the potential development of immune-genomic features in SKCM, we constructed an unprecedented set of immune characteristic genes (EDN3, CLEC4E, SRPX2, KIR2DL4, UBE2L6, and IFIT2) related to the immune landscape of TME. These genes are related to different prognoses and drug responses of SKCM. The immune gene signature constructed can be used as a robust prognostic biomarker of SKCM and a predictor of an immunotherapy effect.

SRPX2 boosts pancreatic cancer chemoresistance by activating PI3K/AKT axis

Background and aim

This investigation was aimed at disclosing whether SRPX2 affected pancreatic cancer (PC) chemoresistance by regulating PI3K/Akt/mTOR signaling.

Methods

Totally 243 PC patients were recruited, and they were incorporated into partial remission (PR) group, stable disease (SD) group and progressive disease (PD) group in accordance with their chemotherapeutic response. PC cell lines (i.e. AsPC1, Capan2, VFPAC-1, HPAC, PANC-1, BxPC-3 and SW1990) and human pancreatic ductal epithelial cell lines (hTERT-HPNE) were also collected.

Results

PC patients of SD + PD group were associated with higher post-chemotherapeutic SRPX2 level than PR group, and their post-chemotherapeutic SRPX2 level was above the pretherapeutic SRPX2 level (P < 0.05). PR population showed lower SRPX2 level after chemotherapy than before chemotherapy (P < 0.05). Besides high serum SRPX2 level and SRPX2 level change before and after chemotherapy were independent predictors of poor PC prognosis. Additionally, si-SRPX2 enhanced chemosensitivity of PC cell lines, and expressions of p-PI3K, p-AKT and p-mTOR were suppressed by si-SRPX2 (P < 0.05). IGF-1 treatment could changeover the impact of si-SRPX2 on proliferation, migration, invasion and chemoresistance of PC cells (P < 0.05).

Conclusion

The SRPX2-PI3K/AKT/mTOR axis could play a role in modifying progression and chemoresistance of PC cells, which might help to improve PC prognosis.

Sushi Repeat Containing Protein X-linked 2 Is a Downstream Signal of LEM Domain Containing 1 and Acts as a Tumor-Promoting Factor in Oral Squamous Cell Carcinoma

Because oral squamous cell carcinomas (OSCCs) have a high potential for locoregional invasion and nodal metastasis, early detection and treatment are essential. A LAP2, emerin, MAN1 (LEM) domain containing 1 (LEMD1) is associated with local progression, clinical stage, nodal metastasis, poor prognosis, angiogenesis, and lymphangiogenesis in OSCC. Although LEMD is a cancer-testis antigen, the cancer-related signals related to LEMD1 remain unknown. In this study, we used a microarray analysis of OSCC cells to identify sushi repeat containing protein X-linked 2 (SRPX2) as a LEMD1-related downstream signal. LEMD1 expression was correlated with lymph node metastasis of OSCC according to the immunohistochemistry analysis. Furthermore, patients expressing SRPX2 had a significantly worse prognosis than those without SRPX2 expression. The concentration of SRPX2 in OSCC was positively correlated with the concentrations of LEMD1, urokinase plasminogen activator receptor (uPAR), and hepatocyte growth factor (HGF). In OSCC cells, SRPX2 secretion levels were elevated by interactions with uPAR and HGF. We also found that SRPX2 promotes endothelial cell proliferation and adhesion between endothelial cells and OSCC cells. These results suggest that SRPX2 might be a useful tumor marker for OSCC.

Downregulated NOX4 underlies a novel inhibitory role of microRNA-137 in prostate cancer

Prostate cancer is the second highest caused by cancer-related death among males. microRNAs (miRs) have been reported to participate in carcinogenesis, yet their roles in prostate cancer are rarely studied or investigated. Therefore, the present study attempted to explore the effect of miR-137 in prostate cancer via regulating NADPH oxidase 4 (NOX4). Initially, microarray analysis was performed to obtain prostate cancer-related differentially expressed genes and miRs that regulated NOX4, followed by detecting the expression of miR-137 and NOX4 and its target relationship. Moreover, PC-3 cells were transfected with small interfering RNA (siNOX4) and miR-137 mimic for exploring the effect of miR-137 on glycolysis, cell proliferation, and apoptosis in prostate cancer by evaluating lactate production, glucose uptake, adenosine triphosphate (ATP) production, viability rate, and expression of cleaved caspases 3, 8, and 9, cytochrome c, cleaved poly ADP ribose polymerase (PARP), Bax, and Bcl-2. miR-137 was vital to prostate cancer progression via regulating NOX4. Besides, miR-137 expressed poorly while NOX4 expressed highly in prostate cancer. NOX4 was the target gene of miR-137. Additionally, overexpression of miR-137 and silencing of NOX4 were observed to decrease NOX4 and Bcl-2 protein expression, but increase cleaved caspases 3, 8, and 9, cytochrome c, cleaved-PARP, and Bax protein expression. Furthermore, miR-137 overexpression and NOX4 silencing contributed to decreased lactate production, glucose uptake, ATP production, and cell proliferation, but increased apoptosis rate. Collectively, the present study showed that miR-137 repressed glycolysis in prostate cancer through knockdown of NOX4, which might be a potential theoretical target for prostate cancer treatment.