UNASSIGNED: Cystatin SA (CST2) plays multiple roles in different types of malignant tumours; however, its role in serous ovarian cancer (SOC) remains unclear. Therefore, we aimed to investigate the expression levels, survival outcomes, immune cell infiltration, proliferation, cell cycle, and underlying molecular mechanisms associated with the CST2 signature in SOC.
UNASSIGNED: The Cancer Genome Atlas database was used to acquire clinical information and CST2 expression profiles from patients with SOC. Wilcoxon rank-sum tests were used to compare CST2 expression levels between SOC and normal ovarian tissues. A prognostic assessment of CST2 was conducted using Cox regression analysis and the Kaplan-Meier method. Differentially expressed genes were identified using functional enrichment analysis. Immune cell infiltration was examined using a single-sample gene set enrichment analysis. Cell cycle characteristics and proliferation were assessed using a colony formation assay, flow cytometry, and a cell counting kit-8 assay. Western blots and quantitative reverse transcription PCR analyses were employed to examine CST2 expressions and related genes involved in the cell cycle and the Wnt-β-catenin signalling pathway.
UNASSIGNED: Our findings revealed significant upregulation of CST2 in SOC, and elevated CST2 expression was correlated with advanced clinicopathological characteristics and unfavourable prognoses. Pathway enrichment analysis highlighted the association between the cell cycle and the Wnt signalling pathway. Moreover, increased CST2 levels were positively correlated with immune cell infiltration. Functionally, CST2 played vital roles in promoting cell proliferation, orchestrating the G1-to-S phase transition, and driving malignant SOC progression through activating the Wnt-β-catenin signalling pathway.
UNASSIGNED: The elevated expression of CST2 may be related to the occurrence and progression of SOC by activating the Wnt-β-catenin pathway. Additionally, our findings suggest that CST2 is a promising novel biomarker with potential applications in therapeutic, prognostic, and diagnostic strategies for SOC.
Serous ovarian cancer is a type of gynecological malignant tumour with high mortality rates. Understanding this disease is crucial for improving treatments and enhancing patient survival. In our study, we investigated a protein called CST2 and its role in serous ovarian cancer. We found that CST2 levels vary among patients and are associated with the progression of cancer and the prognosis of the patient, which could be valuable for future diagnosis and treatment strategies. However, further research is needed to validate these findings. Despite its limitations, our findings suggest that CST2 holds promise as a potential biomarker for detecting serous ovarian cancer and as a therapeutic target in the management of patients with this type of cancer.

OBJECTIVE: Cystatin SA (CST2) belongs to the superfamily of cysteine protease inhibitors. Emerging research indicates that CST2 is often dysregulated across various cancers. Its role and molecular mechanisms in gastric cancer remain underexplored. This study aims to explore the expression and function of CST2 in gastric cancer.
METHODS: CST2 expression was analyzed and validated through Western blot. CST2 overexpression was induced by lentivirus in GC cells, and the correlation between CST2 expression levels and downstream signaling pathways was assessed. In addition, multiple assays, including cell proliferation, colony formation, wound-healing, and transwell migration/invasion, were considered to ascertain the influence of CST2 overexpression on gastric cancer. The cell cycle and apoptosis were detected by flow cytometry.
RESULTS: CST2 expression at the protein level was decreased to be reduced in both gastric cancer tissues and cell lines, and CST2 expression attenuate gastric cancer growth, an effect restricted to gastric cancer cells and absent in gastric epithelial GES-1 cells. Furthermore, CST2 was demonstrated to improve chemosensitivity to Oxaliplatin in gastric cancer cells through the PI3K/AKT signaling pathway.
CONCLUSIONS: These findings indicate that CST2 is downregulated at the protein level in gastric cancer tissues and cell lines. Additionally, CST2 was found to attenuate the growth of gastric cancer cells and to enhance sensitivity to Oxaliplatin through the PI3K/AKT signaling pathway, specific to gastric cancer cell lines. CST2 may serve as a tumor suppressor gene increasing sensitivity to Oxaliplatin in gastric cancer.

Cystatin 2 (CST2) is a protein coding gene that belongs to a large superfamily of cysteine protease inhibitors. The deregulation of CST2 has been implicated in human cancers. The role of CST2 in pancreatic carcinogenesis has not yet been investigated. In this study, Gene Expression Profiling Interactive Analysis was performed using the Cancer Genome Atlas (TCGA) dataset containing pancreatic tumor samples and normal tissues. The functional role of CST2 in pancreatic cells was investigated by gene knockdown in vitro and in mouse xenograft tumor model. We found that CST2 was overexpressed in pancreatic tumor samples and cell lines. The knockdown of CST2 led to reduced proliferation, migration, and invasion, while apoptotic events were increased upon CST2 silencing in pancreatic cancer cells. In the xenograft mouse model of pancreatic cells, CST2 knockdown also retarded tumor growth on tumor growth. RUNX1 was identified as a transcription factor which positively regulated the expression of CST2. Further, we showed that, CST2 knockdown suppressed the activation of the PI3K/AKT signaling in pancreatic cells. Overall, our findings suggest that CST2 serves as an oncogene which facilitates the progression of pancreatic cancer. RUNX1 functions to upregulate CST2 in pancreatic cancer cells and CST2 may promote the malignancy of pancreatic cells by maintaining the activation of PI3K/AKT signaling.

Additional biomarkers for the development and progression of colorectal cancer (CRC) remain to be identified. Hence, the current study aimed to identify potential diagnostic markers for CRC. Analyses of cysteine protease inhibitor [cystatins (CSTs)] expression in CRC samples and its correlation with cancer stage or survival in patients with CRC demonstrated that CRC tissues had greater CST1 and CST2 mRNA expression compared to noncancerous adjacent tissues, while higher CST2 mRNA expression in CRC tissues was correlated with advanced stages and disease-free survival in patients with CRC, encouraging further exploration on the role of CST2 in CRC. Through an online database search and tissue microarray (TMA), we confirmed that CRC samples had higher CST2 expression compared to noncancerous adjacent tissue or normal colorectal tissues at both the mRNA and protein levels. TMA also revealed that colorectal adenoma, CRC, and metastatic CRC tissues exhibited a significantly increased CST2 protein expression. Accordingly, survival analysis demonstrated that the increase in CST2 protein expression was correlated with shorter overall survival of patients with CRC. Moreover, our results found a significant upregulation of CST2 in multiple cancer tissues. Taken together, these findings suggest the potential role of CST2 as a diagnostic and prognostic biomarker for CRC.

Despite the amazing progress in the treatment of gastric cancer (GC), it is still the third leading cause of cancer death in the world. This study explored the key genes that are related to the prognosis and pathogenesis of GC. Data from the cancer genome atlas (TCGA) and Oncomine were applied to evaluate the expression of cystatin 2 (CST2) in GC samples. Kaplan-Meier plotter was carried out to detect the overall survival of GC patients with different expression levels of CST2. Gene Set Enrichment Analysis (GSEA) was carried out to investigate the functions and pathways connected with CST2 expression. Quantitative real-time polymerase chain reaction (qPCR) and Western blot assays were used to assess CST2 expression. The biological properties of GC cells were assessed with the support of cell proliferation and Transwell assays. Important proteins involved in the regulation of CST2 in GC cell behaviors were evaluated by Western blot. Through analysis of the database, we found that CST2 expression was significantly upregulated in GC samples and actively related to GC patients\' poor outcomes. Importantly, the analysis of GSEA showed that GST2 expression was closely connected with the proliferation and migration of cells, as well as the TGF-β1 signaling pathway. In addition, biological assays illustrated that over-expression of CST2 strengthened the activity and metastasis of GC cells. After the upregulation of CST2, the expression of cyclin D1, N-cadherin, vimentin, TGF-β1, and Smad4 increased, and E-cadherin expression decreased. Our findings revealed that over-expression of CST2 enhanced the growth, migration, and invasion of GC cells through modulating the epithelial-mesenchymal transition (EMT) and TGF-β1 signaling pathway, affording a possible biomarker for the treatment of GC.