Transcription factor DDIT3 is a potential driver in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal and aggressive tumor that affects the digestive tract, leading to high mortality and poor survival rates. The purpose of the present study was to evaluate the expression levels of DNA damage-inducible transcript 3 (DDIT3) in pancreatic cancer and to investigate its effects in in vitro and in vivo experiments. Bioinformatics analysis indicated that DDIT3 expression was higher in pancreatic cancer tumor tissues and associated with a poor prognosis. Positive or strong positive DDIT3 expression was observed in PDAC, and no or weak expression was observed in normal pancreatic tissues. It was also highly expressed in PDAC cells, while being expressed at lower levels in normal pancreatic ductal epithelial cells. Transfection of short hairpin RNA targeting the DDIT3 gene reduced the proliferation, migration and invasion of PANC-1 cells. In vivo, in an in situ implantation tumor model with Pan02 cells, the size and weight of the tumors were reduced in the DDIT3 knockdown Pan02 cell-implanted group. These data suggested that DDIT3 represents a novel predictive biomarker for the potential treatment of patients presenting with PDAC.

Engineering c-Met-CAR NK-92 cells as a promising therapeutic candidate for lung adenocarcinoma.

Mesenchymal-epithelial transition factor (C-Met) has been acknowledged as a significant therapeutic target for treating lung adenocarcinoma (LUAD). However, the potential application of chimeric antigen receptors (CAR)-modified natural killer (NK) cells targeting c-Met in LUAD is rarely explored. In this study, bioinformatic databases were searched and a tissue microarray (TMA) was enrolled to investigate expression status and prognostic role of c-Met in LUAD. Then, four types of c-Met-CAR structures were designed and prepared. The engineering CAR-NK cells containing c-Met-CARs were transfected, verified and characterized. The tumor-inhibitory role of c-Met-CAR-NK cells was finally evaluated in vitro and in vivo. The results demonstrated that c-Met expression elevated and confirmed that high c-Met expression was significantly associated with unfavorable prognosis in LUAD. Then, C-Met-CAR-NK cells were successfully constructed and DAP10 designed in CAR structure was a favorable stimulator for NK cell activation. CCN4 containing DAP10 co-stimulator exhibited the strongest cytotoxicity compared with other CAR-NK cells. Furthermore, CCN4 cells also exerted the prominent tumor-inhibitory effect on xenograft tumor growth. Collectively, this study suggests that DAP10 is a potent stimulator in CAR structure for NK cell activation, and CCN4-based immunotherapy may represent a promising strategy for the treatment of c-Met-positive LUAD.

A novel immune checkpoint siglec-15 antibody inhibits LUAD by modulating mφ polarization in TME.

BACKGROUND: Siglec-15 (S15) is a type-I transmembrane protein and is considered a new candidate of immune checkpoint inhibitor for cancer immunotherapy. METHODS: In the present study, we first constructed and characterized a chimeric S15-specific monoclonal antibody (S15-4E6A). Then, the antitumor effectiveness and modulatory role of S15-4E6A in macrophages (mφs) were explored in vitro and in vivo. Finally, the underlying mechanism by which S15mAb inhibits LUAD was preliminarily explored. RESULTS: The results demonstrated the successful construction of S15-4E6A, and S15-4E6A exerted an efficacious tumor-inhibitory effect on LUAD cells and xenografts. S15-4E6A could promote M1-mφ polarization while inhibiting M2-mφ polarization, both in vitro and in vivo. CONCLUSIONS: S15-based immunotherapy that functions by modulating mφ polarization may be a promising strategy for the treatment of S15-positive LUAD.

Proteasome Subunit Alpha Type 7 Promotes Proliferation and Metastasis of Gastric Cancer Through MAPK Signaling Pathway.

BACKGROUND: Proteasome subunit alpha type 7 (PSMA7) shows a carcinogenic effect on various human malignancies, but its role and regulatory mechanism in gastric carcinoma (GC) remain unclear. AIMS: This study aimed to explore the role and mechanism of PSMA7 in GC. METHODS: In this study, PSMA7 expressions in GC cells and tissues were detected, and relationships between PSMA7 and clinicopathological features were explored. Then, PSMA7 levels in human GC cells were intervened, and changes in cell biological behavior were observed in vitro and vivo. Key proteins and downstream factors of MAPK signaling pathway were detected after PSMA7 intervention. RESULTS: PSMA7 was upregulated in GC tissues and cell lines. PSMA7 overexpression was significantly associated with poor pTNM, cTNM stage, and high HP infection. PSMA7 can promote proliferation, invasion, and metastasis of GC cells in vitro and vivo. Furthermore, PSMA7 expression affected the phosphorylation level of JNK, P38, ERK and the expressions of their downstream factors Ap-1, c-myc, P53. CONCLUSION: PSMA7 can promote GC proliferation, invasion, and metastasis through MAPK signaling pathway in GC cells.

DSG2 expression is low in colon cancer and correlates with poor survival.

BACKGROUND: Desmoglein2 (DSG2) is a transmembrane protein that helps regulate intercellular connections and contributes to desmosome assembly. Desmosome are associated with cell adhesion junctions, which play an important role in cancer progression specially cancer cell migration and invasion. However, DSG2 expression in colon cancer (CC) and its association with CC patients' overall survival (OS) are still unclear. METHODS: We collected 587 CC samples, 41 colitis tissues and 114 pericarcinomatous tissues, as well as corresponding clinicopathological data about the patients who contributed them. All samples were tested immunohistochemically in tissue microarrays. Kaplan-Meier method was used for calculating patient survival. Univariate and multivariate analyses was used for investigating DGS2 link with CC patient's clinicopathological factors. Bioinformatics analysis was also used in study. RESULTS: The results showed that DSG2 expression was lower in CC tissues than in pericarcinomatous tissues (P < 0.001). DSG2 expression was associated with differentiation (P = 0.033), lymph node metastasis (P = 0.045), distant metastasis (P = 0.006) and AJCC stage (P < 0.001). Univariate analysis indicated that poor OS in patients with CC was associated with low DSG2 expression (P < 0.001), tumor size (P < 0.001), lymph node metastasis (P < 0.001), distant metastasis (P < 0.001), AJCC stage (P < 0.001) and venous invasion (P < 0.001). In multivariate analysis, low DSG2 expression (P < 0.001), distant metastasis (P < 0.001), AJCC stage (P = 0.002), venous invasion (P < 0.001) were independent prognostic factors for CC patients. Bioinformatics analysis indicated that low DSG2 expression affects protein activation, regulates the P53-related pathway in CC, and activates the EGFR pathway. CONCLUSIONS: The results suggest that low DSG2 expression is associated with poor survival for CC patients. DSG2 could be a prognostic biomarker for CC.

Trop2 Promotes Multidrug Resistance by Regulating Notch1 Signaling Pathway in Gastric Cancer Cells.

BACKGROUND Chemotherapy is widely used in gastric cancer treatment, but multidrug resistance remains a leading cause of chemotherapy failure. Trop2 is highly expressed in gastric tumor tissues and greatly influences cancer progression. However, little is known about the relationship between Trop2 and drug resistance in gastric cancer. MATERIAL AND METHODS In the present study, Trop2 was knocked down in BGC823 cells and overexpressed in HGC27. CCK-8 assay was performed to explore the relationship of Trop2 expression and cell proliferation treated with anticancer drugs. Flow cytometry was performed to assess the relationship between Trop2 and cell apoptosis after chemotherapy. Subcutaneous xenograft models were generated to explore the curative effect of DDP to GC in vivo. MRP1 and Notch1 expressions were assessed by Western blot. RESULTS Trop2 decreased cell proliferation inhibition and apoptosis after chemotherapeutic treatments. DDP showed stronger therapeutic effects on Trop2-knockdown tumor than control in vivo. MRP1 and Notch1 signaling pathway were confirmed to participate in Trop2-induced drug resistance. CONCLUSIONS Our findings suggest that Trop2 promotes the resistance of gastric cancer to chemotherapy by activating the Notch1 pathway.

RNA-Binding Motif 4 (RBM4) Suppresses Tumor Growth and Metastasis in Human Gastric Cancer.

BACKGROUND Dysregulation of the splicing activator, RNA-binding motif 4 (RBM4), has recently been reported to be involved in the progression of several cancers. However, the mechanisms that underpin the activity of RBM4 in gastric cancer (GC) remain unknown. The purpose of our study was to explore how RBM4 affects the biological behavior of GC through in vivo and in vitro experiments. MATERIAL AND METHODS Western blot and flow cytometry analyses were used to investigate the RBM4 protein levels in normal gastric epithelial cells and 5 types of GC cells. Cell Counting Kit-8 assay, flow cytometry analysis, wound-healing, and migration and invasion assays were evaluated in vitro in BGC823 and MGC803 GC cells. A xenograft tumor model was used to assess whether RBM4 inhibits GC growth in vivo. Mitogen-activated protein kinase (MAPK) protein levels were determined using western blot analyses. RESULTS Our study revealed that RBM4 protein was downregulated in GC cells. Re-expression of RBM4 inhibited the proliferation, migration, and invasion of GC cells, while promoting apoptosis. Thus, the overexpression of RBM4 can inhibit tumor growth in GC mouse models. We also report that RBM4 was involved in the activation of MAPK-dependent signaling pathways in human GC. CONCLUSIONS It is hoped that these findings will improve our understanding of GC pathogenesis while also helping us to explore the feasibility of RBM4-targeted therapy for GC treatment.

Human monoclonal anti-protective antigen antibody for the low-dose post-exposure prophylaxis and treatment of Anthrax.

BACKGROUND: Disease caused by Bacillus anthracis is often accompanied by high mortality primarily due to toxin-mediated injury. In the early disease course, anthrax toxins are secreted; thus, antibiotic use is limited to the early stage. In this regard, antibodies against the toxin component, protective antigen (PA), play an important role in protecting against anthrax. Therefore, we developed PA21, a fully human anti-PA immunoglobulin G monoclonal antibody. METHODS: Combining human Fab was screened from a phage library with human heavy constant regions. Enzyme-linked immune sorbent assay, Western blot analysis and immunoprecipitation test evaluated the binding ability of PA21. Moreover, the affinity and neutralizing activity of the antibody was detected in vitro while the protective effectiveness in 60 rats was also examined in vivo. RESULTS: The Fischer 344 rats challenged with the lethal toxin can be protected by PA21 at a concentration of 0.067 mg/kg. All six rats remained alive although PA21 was injected 24 h before the toxin challenge. PA21 did not influence the binding of PA to cell receptors and that of a lethal factor to PA. CONCLUSION: The PA21 monoclonal antibody against PA can be used for emergency prophylaxis and anthrax treatment.

A human Fab exclusively binding to the extracellular domain of LMP2A.

In the areas of North Africa, Southeast Asia as well as South China, Nasopharyngeal carcinoma (NPC) is among the most widespread cancers. Plenty of research findings confirmed that Epstein-Barr virus (EBV) played a crucial role in NPC. EBV-encoded Latent membrane protein 2A (LMP2A) which continuously expressed in cell membrane protein induced an epithelial-mesenchymal transition and increased the number of side population stem-like cancer cells in NPC. This reveals that LMP2A could contribute to the development and recurrence in NPC. Above evidences suggest that LMP2A could be the potential target molecule in the treatment of NPC. In the current study, a novel human antibody Fab (Fab29) against the extracellular domain of LMP2A was produced with success. Through immunofluorescence experiment it was proved that human antibody Fab29 exclusively combined the surface of SUNE cells (LMP2A-positive). Then flow cytometry result exhibited that the fluorescent intensities of SUNE cells and CNE cells were distinct (96.89% and 0.02% respectively). After that, it was shown by affinity test that the Fab29 fragment had high affinity (KD (M) 1.79E-09) with LMP2A. It was also revealed by immunohistochemical analysis that the Fab29 fragment could combine with LMP2A-positive human NPC tissues in comparison with the control group. Finally, the MTT result indicated that the Fab29 fragment could inhibit the proliferation of LMP2A-positive NPC cells. The inhibiting rate to SUNE cell proliferation reached a peak by Fab29 (19.67%) compared with unrelated Fab and CNE with Fab29 at a concentration of 500 µg/L in first 24 h and in the next 24 h the inhibition rate grew to 22.54%. In brief, it was shown that Fab29, a characteristic human antibody, could recognize LMP2A protein and inhibit the proliferation of LMP2A-expressing NPC cells in vitro.

The Fab Fragment of a Humanized Anti-Toll Like Receptor 4 (TLR4) Monoclonal Antibody Reduces the Lipopolysaccharide Response via TLR4 in Mouse Macrophage.

Lipopolysaccharides (LPS) can induce acute inflammation, sepsis, or chronic inflammatory disorders through the Toll receptor 4 (TLR4) signaling pathway. The TLR4/MD2 (myeloid differentiation protein 2) complex plays a major role in the immune response to LPS. However, there is not a good method to suppress the immune response induced by LPS via this complex in macrophages. In this article, we aimed to evaluate the effects of humanized anti-TLR4 monoclonal antibodies on LPS-induced responses in mouse macrophages. The peritoneal macrophages of mice were incubated with anti-TLR4 monoclonal antibodies and stimulated with LPS. The expression levels of cytokines were analyzed by quantitative polymerase chain reaction and enzyme-linked immunosorbent assays. Additionally, activation of various signaling pathways was evaluated by Western blotting. The results showed that the humanized anti-TLR4 monoclonal antibody blocked the inflammatory cytokines expression at both the mRNA and protein level. We also found that the Fab fragment significantly inhibited the nuclear factor kappaB signaling pathway by reducing the phosphorylation of the inhibitor of kappaBalpha and decreasing the translocation of p65, resulting in the suppression of p38, extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase 1/2, and IFN-ß regulatory factor 3 phosphorylation. Therefore, our study showed that this humanized anti-TLR4 monoclonal antibody could effectively protect against LPS-induced responses by blocking the TLR4 signaling pathway in mouse peritoneal macrophages.

A novel human Fab antibody for Trop2 inhibits breast cancer growth in vitro and in vivo.

Human trophoblastic cell surface antigen 2 (Trop2) has been suggested as an oncogene, which is associated with the different types of tumors. In this study, a human Fab antibody against Trop2 extracellular domain was isolated from phage library by phage display technology, and characterized by ELISA, FACS, fluorescence staining and Western blotting analysis. MTT, apoptosis assay and wound healing assay were employed to evaluate the inhibitory effects of Trop2 Fab on breast cancer cell growth in vitro, while tumor-xenograft model was employed to evaluate the inhibitory effects on breast cancer growth in vivo. The results showed that Trop2 Fab inhibited the proliferation, induced the apoptosis and suspended the migration of MDA-MB-231 cells in a dose dependent manner. The expression caspase-3 was activated, and the expression of Bcl-2 was reduced while that of Bax was elevated in MDA-MB-231 cells by treating with Trop2 Fab. In addition, Trop2 Fab inhibited the growth of breast cancer xenografts and the expression of Bcl-2 was reduced while that of Bax was elevated in xenografts. Trop2 Fab, which was isolated successfully in this research, is a promising therapeutic agent for the treatment of Trop2 expressing breast cancer.

Preparation and evaluation of human-murine chimeric antibody against protective antigen of Bacillus anthracis.

The aim of this research is to develop a human/murine chimeric Fab antibody which neutralizes the anthrax toxin, protective antigen (PA). The chimeric Fab was constructed using variable regions of murine anti-PA monoclonal antibody in combination with constant regions of human IgG. The chimeric PA6-Fab was expressed in E. coli. BL21 and evaluated by ELISA and co-immunoprecipitation- mass spectra. The potency of PA6-Fab to neutralize LeTx was examined in J774A.1 cell viability in vitro and in Fisher 344 rats in vivo. The PA6-Fab did not have domain similarity corresponding to the current anti PA mAbs, but specifically bound to anthrax PA at an affinity of 1.76 nM, and was able to neutralize LeTx in vitro and protected 56.9% cells at 20 µg/mL against anthrax LeTx. One hundred µg PA6-Fab could neutralize 300 µg LeTx in vivo. The PA6-Fab has potential as a therapeutic mAb for treatment of anthrax.

Significantly upregulated TACSTD2 and Cyclin D1 correlate with poor prognosis of invasive ductal breast cancer.

The tumor-associated calcium signal transducer 2 (TACSTD2) gene has been reported to be highly expressed in many types of human epithelial cancers, and is associated with tumor metastasis and poor prognosis. The aims of the present investigation were to analyze the TACSTD2 and Cyclin D1 expression at the mRNA and protein levels and to assess its prognostic significance in invasive ductal breast cancer (IDC). The expressions of TACSTD2 and Cyclin D1 in IDC tissues were consistently higher than those in the tumor-adjacent non-malignant tissues by a one-step real-time polymerase chain reaction and immunohistochemistry (P<0.001 and P=0.023, respectively). The statistical analysis of clinicopathologic characteristics and immunohistochemistry by the χ(2) test showed that the high expression of TACSTD2 in IDC was correlated to histological grade (P=0.023), P53 status (P=0.042), Cyclin D1 status (P<0.001), lymph node metastasis (P<0.001), distant metastasis (P=0.004) and TNM staging (P<0.001). Kaplan-Meier survival and Cox regression analyses were performed to evaluate the prognosis of IDC. These analyses also showed that a high TACSTD2 expression (P=0.003), a high Cyclin D1 expression (P=0.041), and lymph node metastasis (P=0.006) were independent prognosis factors. Collectively, our studies demonstrated that the high expression of TACSTD2 correlates with a poor prognosis in IDC.

A novel LMP1 antibody synergizes with mitomycin C to inhibit nasopharyngeal carcinoma growth in vivo through inducing apoptosis and downregulating vascular endothelial growth factor.

Combined therapy emerges as an attractive strategy for cancer treatment. The aim of this study was to investigate the inhibitory effects of mitomycin C (MMC) combined with a novel antibody fragment (Fab) targeting latent membrane protein 1 (LMP1) on nasopharyngeal carcinoma (NPC) xenograft nude mice. The inhibitory rates of MMC (2 mg/kg), Fab (4 mg/kg), MMC (2 mg/kg) + Fab (4 mg/kg), and MMC (1 mg/kg) + Fab (4 mg/kg) were 20.1%, 7.3%, 42.5% and 40.5%, respectively. Flow cytometry analysis showed that the apoptotic rate of xenograft tumor cells in the MMC and Fab combination group was 28 ± 4.12%, significantly higher than the MMC (2 mg/kg) group (P < 0.01). Immunohistochemical staining showed that VEGF expression in NPC xenografts was significantly inhibited in the combination group compared to the Fab (4 mg/kg) group (P < 0.05). In conclusion, both MMC and Fab could inhibit NPC xenograft tumor growth in vivo and combination therapy showed apparent synergistic anti-tumor effects, which may be due to the induction of tumor cell apoptosis and the downregulation of VEGF expression. These results suggest that the novel combined therapy utilizing traditional chemotherapeutics and antibody-targeted therapy could be a promising strategy for the treatment of NPC.

TROP2 Down-regulated DSG2 to Promote Gastric Cancer Cell Invasion and Migration by EGFR/AKT and DSG2/PG/ß-Catenin Pathways.

BACKGROUND: Gastric cancer (GC) is the fourth most commonly found cancer and the second- highest cause of cancer-related death worldwide. TROP2 overexpression is closely related to many cancers, including gastrointestinal tumors. DSG2 is an important protein in cell adhesion, and its loss affects cell migration. AIMS AND OBJECTIVE: This study aimed to explore the specific mechanism of TROP2 in promoting gastric cancer and provide a basis for the prevention and treatment of gastric cancer. METHOD: DSG2 was identified as an interacting protein of TROP2 in GC cells by coimmunoprecipitation and mass spectrometry. The regulated behavior of TROP2 on DSG2 expression was investigated with TROP2 over-expressure or knockdown. Cell-cell adhesion capacity mediated by DSG2 was evaluated by adhesion-related assays. Electron microscope observation was made for accessing GC tumor desmosome assembly. Proteins in EGFR/AKT and DSG2/PG/ß-catenin pathways were evaluated by western blotting. RESULT: This study suggests that abundant expression of TROP2 in GC cells lessened DSG2 levels as well as desmosome adhesion, increased cell invasion and migration, and promoted malignant progression through EGFR/AKT and DSG2/PG/ß-catenin pathways. CONCLUSION: TROP2 promotes cell invasion and migration in gastric cancer by decreasing DSG2 expression through EGFR/AKT and DSG2/PG/ß-catenin pathways.

Transcription factor p8 regulates autophagy in response to disulfiram via PI3K/mTOR/p70S6K signaling pathway in pancreatic cancer cells.

Disulfiram (DSF), which is an inhibitor of aldehyde dehydrogenase (ALDH) and approved by the FDA for the treatment of alcoholism previously, has been repurposed for use as a cancer treatment because of its potent effect in preclinical studies. In this study, we found that disulfiram forms potent complexes with copper (DSF/Cu) inhibited cell proliferation, induced apoptosis in human pancreatic cancer cells, which was detected by flow cytometry and western blotting. Meanwhile, autophagy and autophagic flux also clearly observed by transmission electron microscopy, confocal microscopy and flow cytometry. Our results also showed that DSF/Cu induced transcription factor p8 upregulation and PI3K/mTOR signaling pathway activation detected by real-time PCR and western blotting. Additionally, suppression of p8 inactivated the mTOR signaling pathway and autophagic flux maintained. Furthermore, mechanism study indicated that autophagy induced by DSF/Cu was regulated by p8 and was related to PI3K/mTOR/p70S6K signaling pathway in pancreatic cancer cells. Our findings provide insights into the role of p8 in regulating autophagy induced by DSF/Cu effects in pancreatic cancer cells.

A SARS-CoV-2 neutralizing antibody discovery by single cell sequencing and molecular modeling.

Although vaccines have been developed, mutations of SARS-CoV-2, especially the dominant B.1.617.2 (delta) and B.1.529 (omicron) strains with more than 30 mutations on their spike protein, have caused a significant decline in prophylaxis, calling for the need for drug improvement. Antibodies are drugs preferentially used in infectious diseases and are easy to get from immunized organisms. The current study combined molecular modeling and single memory B cell sequencing to assess candidate sequences before experiments, providing a strategy for the fabrication of SARS-CoV-2 neutralizing antibodies. A total of 128 sequences were obtained after sequencing 196 memory B cells, and 42 sequences were left after merging extremely similar ones and discarding incomplete ones, followed by homology modeling of the antibody variable region. Thirteen candidate sequences were expressed, of which three were tested positive for receptor binding domain recognition but only one was confirmed as having broad neutralization against several SARS-CoV-2 variants. The current study successfully obtained a SARS-CoV-2 antibody with broad neutralizing abilities and provided a strategy for antibody development in emerging infectious diseases using single memory B cell BCR sequencing and computer assistance in antibody fabrication.

Generation and characterization of the human neutralizing antibody fragment Fab091 against rabies virus.

AIM: To transform the human anti-rabies virus glycoprotein (anti-RABVG) single-chain variable fragment (scFv) into a Fab fragment and to analyze its immunological activity. METHODS: The Fab gene was amplified using overlap PCR and inserted into the vector pComb3XSS. The recombinant vector was then transformed into E coli Top10F' for expression and purification. The purified Fab was characterized using SDS-PAGE, Western blotting, indirect ELISA, competitive ELISA, and the fluorescent antibody virus neutralization test (FAVN), respectively, and examined in a Kunming mouse challenge model in vivo. RESULTS: A recombinant vector was constructed. The Fab was expressed in soluble form in E coli Top10F'. Specific binding of the Fab to rabies virus was confirmed by indirect ELISA and immunoprecipitation (IP). The neutralizing antibody titer of Fab was 10.26 IU/mL. The mouse group treated with both vaccine and human rabies immunoglobulin (HRIG)/Fab091 (32 IU/kg) showed protection against rabies, compared with the control group (P<0.05, Logrank test). CONCLUSION: The antibody fragment Fab was shown to be a neutralizing antibody against RABVG. It can be used together with other monoclonal antibodies for post-exposure prophylaxis of rabies virus in future studies.

An active murine-human chimeric Fab antibody derived from Escherichia coli, potential therapy against over-expressing VEGFR2 solid tumors.

Many recombinant murine monoclonal antibodies (mAbs) were studied under pre-clinical or clinical development and became one of the most prolific drug classes in oncology. Vascular endothelial growth factors receptor 2 (VEGFR2) has been implicated to play an important role in tumors. We have established a murine anti-VEGFR2 mAb. To reduce the shortcoming of the mAb, a murine-human chimeric Fab (cFab) named FA8H1 was constructed with gene engineering techniques and expressed as a soluble and functional protein in Escherichia coli Top10F'. Several immunological methods were used to characterize the cFab, including ELISA, affinity and kinetics assay, IP, IF, FACS, and IHC. The results illuminated that cFab maintained the specificity for the VEGFR2 antigen. The active cFab also effectively identified VEGFR2 over-expressing cells in a number of archived human cancer tissues, compared to its parental antibody. The FA8H1 provided the basis for potential therapy research against over-expressing VEGFR2 human solid tumors.