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Abstract Background Esophageal cancer (EC) is one of the malignant tumors with a poor prognosis. The early stage of EC is asymptomatic, so identification of cancer biomarkers is important for early detection and clinical practice. Methods In this study, we compared the protein expression profiles in esophageal squamous cell carcinoma (ESCC) tissues and adjacent normal esophageal tissues from five patients through high-resolution label-free mass spectrometry. Through bioinformatics analysis, we found the differentially expressed proteins of ESCC. To perform the rapid identification of biomarkers, we adopted a high-throughput protein identification technique of Quantitative Dot Blot (QDB). Meanwhile, the QDB results were verified by classical immunohistochemistry. Results In total 2297 proteins were identified, out of which 308 proteins were differentially expressed between ESCC tissues and normal tissues. By bioinformatics analysis, the four up-regulated proteins (PTMA, PAK2, PPP1CA, HMGB2) and the five down-regulated proteins (Caveolin, Integrin beta-1, Collagen alpha-2(VI), Leiomodin-1 and Vinculin) were selected and validated in ESCC by Western Blot. Furthermore, we performed the QDB and IHC analysis in 64 patients and 117 patients, respectively. The PTMA expression was up-regulated gradually along the progression of ESCC, and the PTMA expression ratio between tumor and adjacent normal tissue was significantly increased along with the progression. Therefore, we suggest that PTMA might be a potential candidate biomarker for ESCC. Conclusion In this study, label-free quantitative proteomics combined with QDB revealed that PTMA expression was up-regulated in ESCC tissues, and PTMA might be a potential candidate for ESCC. Since Western Blot cannot achieve rapid and high-throughput screening of mass spectrometry results, the emergence of QDB meets this demand and provides an effective method for the identification of biomarkers.

Abstract Background Mounting evidences have displayed that the dysregulation of miRNAs plays important roles in the pathogenesis of gastric cancer (GC). The purpose of this study was to explore the biological functions and potential mechanism of miR-489 in GC progression. Methods Quantitative real-time PCR (qRT-PCR) and western blot were performed to examine the mRNA expression and protein levels of miR-489 and HDAC7. The relationship between miR-489 and HDAC7 was analyzed by Spearman rank correlation. 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay and transwell assays were conducted for determining the effect of miR-489 and HDAC7 on GC cell viability, migration, and invasion. TargetScan and luciferase reporter assay were used to confirm the target gene of miR-489 in GC cells. Results The findings showed that miR-489 was dramatically decreased in GC tissues and GC cell lines (SGC-7901 and MKN45). Moreover, it was closely correlated with overall survival (OS) and progression-free survival (PFS) of GC patients. Downregulation of miR-489 significantly promoted GC cell proliferation, invasion, and migration. Additionally, HDAC7 was confirmed as the direct target of miR-489. Knockdown of HDAC7 exerted inhibited effect on GC progression and it markedly overturned miR-489 inhibitor-medicated effect on GC cells. More interestingly, via targeting HDAC7, miR-489 blocked the activation of PI3K/AKT pathway in GC cells. Conclusions Correctively, miR-489 played as a tumor suppressor in GC cell growth by targeting HDAC7, and miR-489 might function as a novel biomarker for diagnosis or therapeutic targets of human GC.