Development and clinical evaluation of a rapid antibody lateral flow assay for the diagnosis of SARS-CoV-2 infection.

BACKGROUND: The novel coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has quickly spread worldwide since its outbreak in December 2019. One of the primary measures for controlling the spread of SARS-CoV-2 infection is an accurate assay for its diagnosis. SARS-CoV-2 real-time PCR kits suffer from some limitations, including false-negative results in the clinic. Therefore, there is an urgent need for the development of a rapid antibody test kit for COVID-19 diagnosis. METHODS: The nuclear capsid protein (N) and spike protein 1 (S1) fragments of SARS-CoV-2 were expressed in Escherichia coli, and rapid antibody-based tests for the diagnosis of SARS-CoV-2 infection were developed. To evaluate their clinical applications, the serum from COVID-19 patients, suspected COVID-19 patients, recovering COVID-19 patients, patients with general fever or pulmonary infection, doctors and nurses who worked at the fever clinic, and health professionals was analyzed by the rapid antibody test kits. The serum from patients infected with Mycoplasma pneumoniae and patients with respiratory tract infection was further analyzed to test its cross-reactivity with other respiratory pathogens. RESULTS: A 47 kDa N protein and 67 kDa S1 fragment of SARS-CoV-2 were successfully expressed, purified, and renatured. The rapid antibody test with recombinant N protein showed higher positive rate than the rapid IgM antibody test with recombinant S1 protein. Clinical evaluation showed that the rapid antibody test kit with recombinant N protein had 88.56 % analytical sensitivity and 97.42 % specificity for COVID-19 patients, 53.48 % positive rate for suspected COVID-19 patients, 57.14 % positive rate for recovering COVID-19 patients, and 0.5-0.8 % cross-reactivity with other respiratory pathogens. The analytical sensitivity of the kit did not significantly differ in COVID-19 patients with different disease courses (p < 0.01). CONCLUSIONS: The rapid antibody test kit with recombinant N protein has high specificity and analytical sensitivity, and can be used for the diagnosis of SARS-CoV-2 infection combined with RT-PCR.

CDX2 and Reg IV expression and correlation in gastric cancer.

BACKGROUND: Ectopic expression of CDX2 is associated with the development and progression of gastric cancer. Previous studies showed that CDX2 may be an upstream regulator of Reg IV expression in gastric cancer, and our previous report showed that Reg IV upregulated SOX9 expression and enhanced cell migration and invasion in gastric cancer cells. However, the regulatory roles of CDX2 have not been clarified in gastric cancer, and the correlation between CDX2 and Reg IV requires further study. METHODS: CDX2 and Reg IV were examined in gastric cancer specimens and paired adjacent tissues via real-time PCR and immunohistochemistry (IHC). The association between CDX2 and Reg IV was assessed using the χ2-test and Spearman's rank correlation. To verify their relationship, knockdown and exogenous expression of CDX2 or Reg IV were performed in AGS and MKN-45 gastric cancer cells, and their expression was subsequently analyzed via a real-time PCR and western blotting. Wound-healing and Transwell assays were used to examine migration and invasion in AGS and MKN-45 cells following CDX2 silencing or overexpression. RESULTS: A positive correlation was observed between CDX2 and Reg IV expression at the mRNA and protein levels in gastric cancer tissues. CDX2 silencing significantly downregulated Reg IV expression, and CDX2 overexpression significantly upregulated Reg IV expression in AGS and MKN-45 cells. Neither Reg IV silencing nor overexpression had any effect on CDX2 protein expression in AGS or MKN-45 cells, even though both affected the expression of CDX2 mRNA. Functionally, CDX2 silencing significantly inhibited cell migration and invasion, and CDX2 overexpression significantly promoted cell migration and invasion in AGS and MKN-45 cells. CONCLUSIONS: Our findings demonstrate that CDX2 expression was positively correlated with that of Reg IV in gastric cancer, and CDX2 promoted cell migration and invasion through upregulation of Reg IV expression in AGS and MKN-45 cells.

ß2-microglobulin has a different regulatory molecular mechanism between ER+ and ER- breast cancer with HER2.

BACKGROUND: Previous studies have demonstrated that ß2-microglobulin (ß2M) promotes the growth and survival of a variety of cancer cells and has different regulatory effects on the expression of Bcl-2 and HER2 in HER2- breast cancer cells. However, ß2M-mediated signaling in ER+ and ER- breast cancer with HER2- remains unclear. METHODS: ß2M expression vector and siRNA were transfected into two types of HER2- breast cancer cells, and the possible relevant signaling molecules were subsequently analyzed by real-time PCR and western blotting. These signaling molecules were also analyzed by real-time PCR and immunohistochemistry (IHC) in two types of HER2- breast cancer tissues, and the associations between ß2M and these signaling molecules were assessed using Spearman's correlation analysis. RESULTS: ß2M silencing downregulated p-SGK1/SGK1 levels and Bcl-2 expression, and ß2M overexpression downregulated p-CREB/CREB and significantly upregulated p-SGK1/SGK1 levels and Bcl-2 expression, and both resulting processes did not affect HER2, HIF-1α, VEGF, and ERK signaling in ER+ breast cancer cells with HER2-. ß2M silencing upregulated p-CREB/CREB and VEGF protein and significantly downregulated p-ERK/ERK levels, and ß2M overexpression downregulated p-CREB/CREB and VEGF, significantly upregulated p-ERK/ERK levels, and both resulting processes did not affect HIF-1α and SGK1 signaling in ER- breast cancer cells with HER2-. ß2M expression was positively correlated with p-CREB, p-SGK1, and Bcl-2 expression and had no correlation with HIF-1α, VEGF, and p-ERK1/2, whereas p-SGK1 exhibited a significantly positive correlation with Bcl-2 expression in cancer tissues of patients with luminal A breast cancer, which coincide with the results obtained from the same molecular types of breast cancer cells except CREB signaling. However, ß2M expression did not show a significant correlation with HIF-1α, p-CREB, VEGF, p-SGK1, p-ERK1/2, and Bcl-2 expression in cancer tissues of patients with basal-like breast cancer, which was discordant with the results obtained from the same molecular types of breast cancer cells. CONCLUSIONS: ß2M has a different molecular regulatory mechanism between ER+ and ER- breast cancer with HER2-, and it may promote tumor survival through the SGK1/Bcl-2 signaling pathway in ER+ breast cancer with HER2- and has no regulatory effects on ER- breast cancer with HER2-.

Expression of Reg IV and SOX9 and their correlation in human gastric cancer.

BACKGROUND: Reg IV is a member of the regenerating gene family and has been demonstrated to be overexpressed in gastric cancer. However, the functional mechanism of Reg IV in gastric cancer is still unclear. METHODS: Expression of Reg IV and SOX9 were investigated by immunohistochemistry (IHC) and real-time PCR, and the correlation between the expression of Reg IV and SOX9 was analyzed in gastric cancer tissues. Reg IV expression vectors and a siRNA of Reg IV and SOX9 were transfected into human gastric cancer cells and the protein and mRNA levels of Reg IV and SOX9 were investigated by western blot and real-time PCR. The invasion and migration ability of gastric cancer cells with overexpressed Reg IV and with gene silence of Reg IV and SOX9 were examined by transwell chambers and wound healing assay. RESULTS: The Reg IV and SOX9 protein expression levels were both significantly higher in gastric cancer tissues compared with adjacent tissues (p = 0.022, p = 0.003). Reg IV protein expression significantly correlated with tumor invasion depth (p <  0.001), but had no significant correlations with age, clinical stage or lymph node metastasis. SOX9 protein expression also had no significant correlations with age, clinical stage, tumor invasion depth or lymph node metastasis. Reg IV transcript expression demonstrated a significant correlation with invasion depth and lymph node metastasis (p = 0.005, p <  0.001) and no significant correlations with age, clinical stage, tumor tissue differentiation or tumor size. SOX9 transcript expression demonstrated a significant correlation with invasion depth and tumor tissue differentiation (p = 0.044, p = 0.007) and no significant correlations with age, clinical stage or tumor size. The Reg IV expression showed a positive correlation with the SOX9 expression (p <  0.000, p = 0.008). Overexpression of Reg IV could upregulate SOX9 expression and promote invasiveness and migration of tumor cells, and silencing of Reg IV could downregulate SOX9 and inhibit invasiveness and migration of tumor cells in MKN-45 and AGS cells. On the other hand, silencing of SOX9 could upregulate Reg IV protein expression. CONCLUSIONS: Our study demonstrated that Reg IV positively regulates the expression of SOX9 and is involved in tumor cell invasion and migration in gastric cancer.

Establishment and characterization of a metastasis model of human gastric cancer in nude mice.

BACKGROUND: A mouse model of metastasis of human gastric cancer is one of the most important tools for studying the biological mechanisms underlying human gastric cancer metastasis. In this paper, we established a mouse model of metastatic human gastric cancer in nude mice that has a higher rate of tumor formation and metastasis than existing models. METHODS: To generate the mouse model of metastatic human gastric cancer, fresh tumor tissues from patients that have undergone surgery for gastric cancer were subcutaneously implanted in the right and left groins of nude mice. When the implanted tissue grew to 1 cubic centimeter, the mice were killed, and the tumor tissues were examined and resected. The tumor tissues were implanted into nude mice and subjected to pathological examination, immunohistochemical staining, and real-time PCR for cytokeratin 8/18 (CK8/18), E-cadherin, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1). The mice were also analyzed for metastasis in their peritoneum, abdominal cavity, and internal organs by histopathological examination. Tissues collected from these organs were examined for pathology. RESULTS: After ten generations of implantation, all mice developed tumor growth at the implanted position, 94% of the mice developed metastasis to the retroperitoneum and viscera. The implanted and metastatic tumor maintained the same histological features across all generations, and metastasis was observed in the esophagus, stomach, spleen, liver, kidney, adrenal, intestine, and pancreas. These metastatic tumors revealed no detectable expression of CK8/18, E-cadherin, VCAM-1, and ICAM-1. CONCLUSIONS: This model will serve as valuable tool for understanding the metastatic process of human gastric cancer.

Characterization of ß2-microglobulin expression in different types of breast cancer.

BACKGROUND: Βeta-2-microglobulin (ß2-M) has been demonstrated as a growth factor and signaling molecule in breast cancer and leukemia. The purpose of the study is to characterize ß2-M expression in molecular subtypes of breast cancer, thereby investigating the mechanism of ß2-M action in breast cancer. METHODS: ß2-M and B-Cell Lymphoma/Leukemia 2 (Bcl-2) transcript expression levels in breast cancer tissue and the corresponding normal tissue were quantified using real-time PCR. The protein expression levels of ß2-M, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER-2), tumor protein 53 (p53) and Ki67 were determined by immunohistochemical (IHC) staining. Following silencing of the ß2-M by siRNA, the levels of Bcl-2, ER, PR and HER-2 transcripts and the protein expression levels in human breast cancer cells were measured by real-time PCR and western blotting, respectively. RESULTS: The expression of ß2-M transcripts demonstrated no significant differences between the four breast cancer molecular subtypes and no significant correlations with age, clinical stage or lymph node metastasis. ß2-M transcript expression demonstrated a positive correlation when compared to Bcl-2 transcript expression (P<0.05). The ß2-M protein expression was significantly higher in breast cancer when compared with benign breast tumors (P<0.01), and have no significant correlation with age, clinical stage or lymph node metastasis. There was a significant difference demonstrated in ß2-M protein expression in the four breast cancer molecular subtypes (P<0.05), and between the ER+ and ER- groups (P<0.01); however, no significant difference was demonstrated between the HER-2+ and HER-2- groups. ß2-M protein expression had a negative correlation with ER protein expression (P<0.01), a positive correlation with p53 protein expression (P<0.01), and no correlation with Ki67 protein expression. ß2-M silencing significantly inhibited Bcl-2 mRNA expression, but did not inhibit ER, PR and HER-2 mRNA expression in MCF-7 cells (ER+, PR+ and HER-2-). In addition, Bcl-2 and HER-2 mRNA expression were significantly up-regulated in MDA-MB-231 cells (ER-, PR- and HER-2-), which is consistent with the silencing effect seen at the protein level. CONCLUSIONS: ß2-M expression demonstrated a significant difference in the four breast cancer molecular subtypes, and may be related to apoptosis regulation in breast cancer.

[Development and characterization of monoclonal antibodies against VP1 protein of AsiaI type foot-and-mouth virus].

AIM: To prepare the monoclonal antibodies against VP1 protein of type AsiaI foot-and mouth disease virus (FMDV) and identify the characterization. METHODS: Three cell of hybridization that strains secreted monoclonal antibody(mAb) against type AsiaI FMDV were produced by fusing mouse myeloma cells (Sp2/0) with spleen cells from BALB/c immunized with the purified recombinant VP1 protein. RESULTS: The three hybridized cell lines reacted with cattle type AsiaI FMDV, the titres of ascetic fluids of the three mAbs ranged from 1:10(5) to 1:10(6) indirect ELISA showed. Among the three mAbs,1B8 belonged to IgG1, 5E1 and 5E2 pertained to IgG2a. Besides, the three strain antibodies stably excreted antibodies and reacted with type AsiaI FMDV. CONCLUSION: VP1 protein of FMDV could replace FMDV can be use to replace FMDV to prepare mAbs.