SCUBE2 as a Marker of Resistance to Taxane-based Neoadjuvant Chemotherapy and a Potential Therapeutic Target in Breast Cancer

Objective

Taxane-based neoadjuvant chemotherapy is the most common neoadjuvant approach in breast cancer, especially in human epidermal growth factor receptor 2 (HER2)-positive and triple-negative subtypes. However, chemoresistance is a problem in many patients, and success rates are low in estrogen receptor (ER)-positive breast cancer. The aim of this study was to identify predictive markers for resistance to taxane-based therapy, which may have a potential as therapeutic targets in breast cancer.

Materials and Methods

Three comprehensive breast cancer Gene Expression Omnibus datasets were analyzed to identify differentially expressed genes (DEGs) in breast cancer patients resistant to taxane-based neoadjuvant chemotherapy. Functional annotation clustering and enrichment analysis were performed on the DEGs list. A protein-protein interaction network was established with the upregulated genes. The predictive value and the differential expression of the central genes were validated in the extensive ROC Plotter database.

Results

Seventeen upregulated genes were found which were associated with resistance to taxane-based neoadjuvant therapy and high connectivity in the network analysis. ESR1, CCND1, and SCUBE2 emerged as the top three key genes associated with resistance. SCUBE2 displayed a high predictive power comparable to ESR1, and better than CCND1, the two commonly accepted markers. The predictive ability of SCUBE2 was higher in ER-positive and HER2-positive breast cancers.

Conclusion

These results suggest that SCUBE2 may be used as a predictive marker to guide decisions on neoadjuvant therapy. Emerging evidence about the role of SCUBE2 as a coreceptor involved in tumor progression and angiogenesis also suggests SCUBE2 as a potential therapeutic target. These points should be investigated in further studies.

Knockdown of circ_0025908 inhibits proliferation, migration, invasion, and inflammation while stimulates apoptosis in fibroblast-like synoviocytes by regulating miR-650-dependent SCUBE2

BACKGROUND

Circular RNAs (circRNAs) are demonstrated to play vital roles in human diseases, including rheumatoid arthritis (RA). Therefore, this research aimed to explore the effects of hsa_circRNA_0025908 (circ_0025908) on RA.

METHODS

RNA expression of circ_0025908, microRNA-650 (miR-650), and Signal peptide-CUBepidermal growth factor-like containing protein 2 (SCUBE2) were assessed by real-time quantitative polymerase chain reaction; protein expression of SCUBE2, apoptosis- and invasion-related proteins was evaluated by western blot assay. Functional assays were performed using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazol-3-ium bromide, 5-ethynyl-2'-deoxyuridine, transwell, flow cytometry, and enzyme linked immunosorbent assay assays. Dual-luciferase reporter, RNA immunoprecipitation, and RNA pull-down assays confirmed the interaction relationship among circ_0025908, miR-650, and SCUBE2.

RESULTS

Circ_0025908 was overexpressed in synovial tissues and fibroblast-like synoviocytes (FLS) from RA patients. Inhibition of circ_0025908 repressed proliferation, migration, invasion, inflammation, and cell cycle progression, while induced apoptosis in the FLS isolated from RA patients (FLS-RA), accompanied with increased Bax, cleaved caspase-3 and E-cadherin, but declined Bcl-2, N-cadherin and Vimentin. MiR-650 was a target of circ_0025908, and SCUBE2 was a target for miR-650. Silencing of miR-650 could overturned above effects of circ_0025908 knockdown in FLS-RA, whereas its overexpression could mimic those effects by downregulating SCUBE2. Additionally, SCUBE2 expression could be positively regulated by circ_0025908 and inversely regulated by miR-650. Notably, Pearson's correlation analysis confirmed the linear correlation among circ_0025908, miR-650 and SCUBE2 in these RA tissues.

CONCLUSION

Circ_0025908 inhibition can suppress FLS-RA dysfunctions through targeting miR-650/SCUBE2 axis, suggesting a new potential therapeutic clue for RA patients.

Expression of SCUBE2 and BCL2 Predicts Favorable Response in ERα Positive Breast Cancer

BACKGROUND

The study aimed at evaluating steroid biomarker genes (ERα, PGR, ERβ) and determining the expression level of estrogen-regulated genes (SCUB2 and BCL2) and growth factors receptors (HER2 and IGFR1) in cancer tissue samples obtained from Iranian patients with breast cancer. Moreover, relationships with clinicopathologic aspects of tumor and response to treatment were studied.

METHODS

The current study was conducted on 246 breast tissue samples. The expression levels of these genes and their relationships with clinicopathologic aspects and treatment response were evaluated.

RESULTS

Based on immunohistochemistry (IHC) results, 12% of the ER negative patients expressed ERα. Comparing the effects of ERα and coexpression of BCL2 and SCUBE2 on the survival of the patients demonstrated remarkably poorer survival in ERα positive, SCUBE2, and BCL2 negative groups in comparison with other patients, which was statistically significant in the log-rank analysis (P = 0.01). Evaluation of the effects of coexpression of HER2 and IGFR1 on patients' survival demonstrated a worse survival rate in patients with positive expression of both receptors, which was insignificant.

CONCLUSION

Many studies suggest that PGR alone is not enough for the functional evaluation of ERα. Evaluation of the progesterone receptor expression as well as other genes such as BLC2, SCUBE2, and IGFR1, seems necessary to evaluate functionality.

Circular RNA circ_SETD2 represses breast cancer progression via modulating the miR-155-5p/SCUBE2 axis

Breast cancer (BC) is the leading cause of cancer deaths in women worldwide. Circular RNA circ_SETD2 (circ_SETD2), also termed as hsa_circ_0065173, is reported to be abnormally expressed in BC. Nevertheless, the role and mechanism of circ_SETD2 in BC are unclear. Expression of circ_SETD2, miR-155-5p, and SCUBE2 mRNA was evaluated by quantitative real-time polymerase chain reaction. Cell cycle progression, proliferation, apoptosis, migration, and invasion were determined by flow cytometry, MTT, and transwell assays. The relationship between circ_SETD2 or SCUBE2 and miR-155-5p was verified through a dual-luciferase reporter assay. The role of circ_SETD2 in BC in vivo was confirmed by a xenograft assay. circ_SETD2 and SCUBE2 were downregulated, while miR-155-5p was upregulated in BC tissues and cells. Both circ_SETD2 and SCUBE2 elevation arrested cell cycle progression, inhibited cell proliferation, migration, and invasion, and accelerated cell apoptosis in BC cells. Moreover, circ_SETD2 upregulation repressed BC growth in vivo. Importantly, circ_SETD2 modulated SCUBE2 expression through competitively binding to miR-155-5p in BC cells. Also, the inhibitory impacts of circ_SETD2 enhancement on the malignant behavior of BC cells were restored by miR-155-5p overexpression. Besides, SCUBE2 silencing abolished miR-155-5p downregulation mediated effects on the malignant behavior of BC cells. Therefore, circ_SETD2 curbed BC progression via upregulating SCUBE2 via binding to miR-155-5p.

Knockdown of long non-coding RNA PVT1 induces apoptosis of fibroblast-like synoviocytes through modulating miR-543-dependent SCUBE2 in rheumatoid arthritis

Background

Rheumatoid arthritis (RA), a kind of autoimmune disorder, is featured by many physical symptoms and proliferation of fibroblast-like synoviocytes (FLSs). The relevance of long non-coding RNAs (lncRNAs) in the progression of RA has been probed. Hence, the goal of this report was to investigate the action of plasmacytoma variant translocation 1 (PVT1), a lncRNA, in FLSs and the basic mechanism.

Methods

Initially, RA rats were developed to evaluate the expression of PVT1, microRNA-543 (miR-543), and signal peptide-CUB-EGF-like containing protein 2 (SCUBE2) in synovial tissues. Enhancement or loss of PVT1 or miR-543 was achieved to explore their effects on proliferation, cell cycle, and apoptosis of FLSs. The interaction between PVT1 and miR-543 and between miR-543 and its putative target SCUBE2 was examined to elucidate the correlations. Finally, the protein expression of proliferation- and apoptosis-associated genes were assessed by western blot assays.

Results

PVT1 was overexpressed in synovial tissues from RA patients through microarray expression profiles. The PVT1 and SCUBE2 expression was boosted, and miR-543 was reduced in synovial tissues of rats with RA. PVT1 specifically bound to miR-543, and miR-543 negatively regulated SCUBE2 expression. Overexpression of PVT1 or silencing of miR-543 enhanced SCUBE2 expression, thereby promoting proliferation and interleukin-1β (IL-1β) secretion, while inhibiting apoptosis rate of FLSs. Conversely, si-SCUBE2 reversed the role of miR-543 inhibitor.

Conclusion

The key findings support that PVT1 knockdown has the potency to hinder RA progression by inhibiting SCUBE2 expression to sponge miR-543.

SCUBE2, vascular endothelium, and vascular complications: A systematic review

The vascular endothelium plays a vital role in regulating normal vascular function. Endothelial lining maintains the balance of thrombolytic and fibrinolytic microenvironment in the vasculature. Alterations of vascular endothelium referred to as endothelial dysfunction, caused the pathological changes in vessel wall such activation of proinflammatory and procoagulatory that initiate atherosclerosis. The concept that endothelial dysfunction plays a critical role in the initiation of atherosclerosis due to vascular inflammation gained tremendous attention. Diabetes mellitus is a metabolic-related disease that caused high mortality and morbidity, leading to its cardiovascular complication over the past decade. Atherosclerosis is the leading cardiovascular complication in diabetes mellitus. Despite metabolic and glycemic control, atherosclerotic plaque progression remains an enormous problem in diabetes mellitus complications. Thus, new inroads therapeutic approach in preventing complications that induced inflammation in endothelial cells could help prevent the disease progression. Signal peptide-CUB-EGF like domain-containing protein 2 (SCUBE2) expressed in vascular endothelium and reported to involve in inflammation. A recent study reported an increased SCUBE2 expression in diabetes mellitus and correlated with high expression of endothelin-1 (ET-1), a proinflammatory endothelial cell-derived peptide. Moreover, this gene showed to increase during atherosclerosis development. The present systematic review will summarize the involvement of SCUBE2 in vascular endothelium function changes and vascular complication, particularly in diabetes mellitus and atherosclerosis.

Upregulation of SCUBE2 expression in dyslipidemic type 2 diabetes mellitus is associated with endothelin-1

Type 2 diabetes mellitus (T2DM) is a major health problem for morbidity and mortality world-wide due to diabetic vascular complication. Following T2DM, dyslipidemia is known well for the main reason of vascular complication leading to atherosclerosis and impaired life expectancy in diabetes. Thus, a new prediction marker in T2DM could help prevent the progression disease despite of metabolic control. Signal peptide-CUB-EGF like containing protein 2 (SCUBE2), has been detected in vascular endothelium and was affected by cytokines. Recently, SCUBE2 was reported to increase in atherosclerotic human coronary artery, involving vascular smooth muscle cells (VSMCs) and macrophages. The aims of this study were to examine the expression level of SCUBE2 in T2DM patients with dyslipidemia and its correlation with endothelial dysfunction marker, endothelin-1 (ET-1) in this group. This study design was cross sectional control study, recruited 28 patients diagnosed as T2DM who were found with dyslipidemia and 15 healthy control subjects. Our results showed that T2DM patients showed higher LDL cholesterol, triglycerides, and ET-1 expression level compared to healthy subjects. Further, we found that SCUBE2 had strong correlation with ET-1 in these dyslipidemic T2DM patients. In conclusion, our study confirmed first that SCUBE2 was upregulated in T2DM with dyslipidemia. Moreover, Pearson correlation analysis of ET-1 and SCUBE2 in this group showed high correlation r = 0.797, P < 0.001, suggesting that SCUBE2 may plausible target in vascular function changes in dyslipidemic T2DM. Improving our exploration of these findings may lead to uncover SCUBE2 involvement in diabetic vascular complication in T2DM.

Candidate Predisposition Variants in Kaposi Sarcoma as Detected by Whole-Genome Sequencing

Familial clustering of classic Kaposi sarcoma (CKS) is rare with, approximately 100 families reported to date. We studied 2 consanguineous families, 1 Iranian and 1 Israeli, with multiple cases of adult CKS and without overt underlying immunodeficiency. We performed genome-wide linkage analysis and whole-genome sequencing to discover the putative genetic cause for predisposition. A 9-kb homozygous intronic deletion in RP11-259O2.1 in the Iranian family and 2 homozygous variants, 1 in SCUBE2 and the other in CDHR5, in the Israeli family were identified as possible candidates. The presented variants provide a robust starting point for validation in independent samples.

Upregulated SCUBE2 expression in breast cancer stem cells enhances triple negative breast cancer aggression through modulation of notch signaling and epithelial-to-mesenchymal transition

BACKGROUND

Metastatic and/or recurrent breast carcinomas are leading causes of cancer-related death worldwide. Breast cancer stem cells (BCSCs) have been implicated in cancer metastases and progression, thus, the need for the discovery and development of effective BCSCs-specific therapies against metastatic and triple negative breast cancer (TNBC). The expression of SCUBE2, originally identified in vascular endothelia, then in several non-endothelial cell types, is downregulated in invasive breast carcinomas. However, the role of SCUBE2 in BCSCs remains unknown. This present study investigated the probable involvements of SCUBE2 in BCSCs and TNBC metastasis.

METHODS

The mRNA expression of SCUBE2, stemness and EMT markers in MDA-MB-231 and Hs578T tumorspheres or adherent cells were evaluated by qRT-PCR and microarray analyses. Using gene overexpression, in vitro migration and invasion assays, as well as in vivo bioluminescence imaging, we evaluated the role of SCUBE2 in MDA-MB-231 or Hs578T BCSCs. Western blot and cytotoxicity assays helped identify and validate SCUBE2 molecular target(s) and inhibitor(s).

RESULTS

Concurrently increased SCUBE2 expression and cell motility were observed in TNBC tumorspheres compared to the parental adherent cells. SCUBE2 overexpression augmented BCSCs motility in vitro, and enhanced TNBC metastasis in vivo. While SCUBE2 overexpression activated Notch signaling its downregulation suppressed Notch signal effectors NICD, Jagged 1, HEY1, and HES1.

CONCLUSIONS

We demonstrate that SCUBE2 expression is upregulated in BCSCs, promote EMT and enhance TNBC metastasis by activating Notch signaling. This reveals a potential druggable molecular target and an effective therapeutic strategy against metastatic and aggressive TNBC.

Inhibition of Endothelial SCUBE2 (Signal Peptide-CUB-EGF Domain-Containing Protein 2), a Novel VEGFR2 (Vascular Endothelial Growth Factor Receptor 2) Coreceptor, Suppresses Tumor Angiogenesis

OBJECTIVE

SCUBE2 (signal peptide-CUB-EGF domain-containing protein 2), expressed on the endothelial cell surface, functions as a novel coreceptor for VEGFR2 (vascular endothelial growth factor receptor 2) and enhances VEGF-induced signaling in adult angiogenesis. However, whether SCUBE2 plays a role in pathological angiogenesis and whether anti-SCUBE2 antibody is an effective strategy for blocking tumor angiogenesis remain unknown. The aim of this study was to investigate the pathological role and targeting therapy of SCUBE2 in tumor vasculature.

APPROACH AND RESULTS

Immunohistochemistry revealed that SCUBE2 is highly expressed in endothelial cells of numerous carcinomas. Genetic endothelial cell knockout of SCUBE2 and pharmacological inhibition with the anti-SCUBE2 monoclonal antibody SP.B1 significantly reduced xenograft tumor growth, decreased tumor vascular density, increased apoptosis, and decreased the proliferation of tumor cells. Mechanistic studies revealed that SP.B1 binds to SCUBE2 and induces its internalization for lysosomal degradation, thereby reducing its cell surface level and inhibiting the binding of and downstream signaling of VEGF, including VEGFR2 phosphorylation and AKT/MAPK (mitogen-activated protein kinase) activation. Importantly, dual combination therapy with anti-SCUBE2 monoclonal antibody and anti-VEGF antibody or chemotherapy was more effective than single-agent therapy.

CONCLUSIONS

Endothelial cell surface SCUBE2 is a VEGFR2 coreceptor essential for pathological tumor angiogenesis, and anti-SCUBE2 monoclonal antibody acting as an internalization inducer may provide a potent combination therapy for tumor angiogenesis.

Reduced expression of SCUBE2 predicts poor prognosis in gastric cancer patients

Signal peptide-CUB-EGF (epidermal growth factor) domain-containing protein 2 (SCUBE2) is a secreted cell-surface glycoprotein. Decreased SCUBE2 expression has been reported in a variety of human cancers, including breast cancer, but its role in gastric cancer (GC) is still unknown. The present study was designed to evaluate the role of SCUBE2 expression in the prognosis of GC patients. SCUBE2 expression in GC tissues was detected by quantitative real-time reverse transcription polymerase chain reaction, Western blotting, and immunohistochemistry. The association between SCUBE2 expression and clinicopathological characteristics was evaluated using the Chi-square test. The Kaplan-Meier method and Cox proportional hazards models were applied to estimate the effect of SCUBE2 expression on survival. Our results show that expression of SCUBE2 in GC tissues is significantly lower than that in adjacent normal gastric mucosa tissues. Loss of SCUBE2 expression was associated with larger tumors (P = 0.001), advanced clinical stage (P = 0.001), T3 or T4 lesion (P = 0.017), lymph node metastasis (P = 0.033), higher histological grade (P = 0.041), and vascular invasion (P = 0.002). Patients with decreased SCUBE2 expression showed poorer recurrence free survival (RFS) and overall survival (OS) than those with higher SCUBE2 expression levels. Furthermore, multivariate analysis indicated that reduced expression of SCUBE2 was an independent prognostic factor predicting poor RFS (HR = 1.764, P = 0.029) and OS (HR = 1.811, P = 0.026). Therefore, expression of SCUBE2 in GC tends to be downregulated, and may serve an important role in predicting the prognosis of GC patients.