Background Monoclonal antibodies (mAbs) have been used for cancer therapy. They are large and have some disadvantages limiting their use. Smaller antibody fragments are needed as their alternatives. A fully human single-domain antibody (sdAb) has a small size of only 15 kDa and consists of only the variable domain of the human antibody heavy chain (VH). It has no immunogenicity. It can easily penetrate into tumor tissues, target an epitope inaccessible to mAb and be manufactured in bacteria for a low cost. Epidermal growth factor receptor (EGFR) is over-expressed in many cancer cells and is a good target for cancer therapy. Methods The EGFR protein fragment located on the EGFR extracellular domain III was chosen to screen a human sdAb library. Five human anti-EGFR sdAbs were identified. Their specific binding to EGFR was confirmed by ELISA, Western blotting and flow cytometry. Their anti-tumor effects were tested. Results Five novel fully human anti-EGFR sdAbs were isolated. They specifically bound to EGFR, not to the seven unrelated proteins as negative controls. They also bound to the three different human cancer cell lines, but not to the two cell lines as negative controls. They inhibited cell proliferation, migration and invasion and increased apoptosis of these three cancer cell lines. Two of them were tested for their anti-tumor effect in vivo and showed the anti-tumor activity in a mouse xenograft model for human lung cancer. Immunohistochemical staining of xenograft tumors also showed that their anti-tumor effects were associated with the inhibition of cancer cell proliferation and the promotion of cancer cell apoptosis. Conclusions This study clearly demonstrated that the anti-EGFR sdAbs could inhibit cancer cell growth in vitro and tumor growth in vivo. They could be potential therapeutics for the treatment of different human cancers.

Over-expression of vitronectin (VN) is associated with tumorigenesis. The present study aimed to evaluate the prognostic value of VN expression in gastric cancer.The least absolute shrinkage and selection operator analysis was performed to screen the hub gene from The Cancer Genome Atlas gastric cancer patients with complete follow-up data, and 347 patients were finally included. Moreover, 102 patients were enrolled from the Affiliated Fuzhou First Hospital of Fujian Medical University. VN expression in paired gastric cancer and adjacent gastric normal tissues was detected using immunohistochemistry, and the clinicopathological significance of VN expression was evaluated. The prognostic significance of VN expression in gastric cancer patients was evaluated using by Kaplan-Meier method and Cox regression analysis and confirmed using Oncomine.VN was the prognosis relative gene which screened by The Cancer Genome Atlas dataset. Moreover, we identified the VN expression in an external dataset by immunohistochemistry. The result demonstrated that VN expression was remarkedly elevated in gastric cancer tissues (P < .001). High VN expression correlated with higher pathological Tumor-Node-Metastasis stage, and poorer survival outcomes. Cox regression analysis showed that VN expression was independently predictive of overall survival (OS) and disease-free survival (P = .004, P < .001, respectively). A prognostic risk score for OS was built based on VN expression. A metaanalysis from Oncomine datasets revealed that significantly lower VN mRNA levels in gastric cancer correlated with poorer OS.VN expression could be a prognostic marker of gastric cancer.

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