Overexpression of p42.3 promotes cell proliferation, migration, and invasion in human gastric cancer cells.

As a newly discovered tumor-specific gene, p42.3 is overexpressed in most of human gastric cancers (GC). However, the role of p42.3 in GC progression remains unclear. To assess the role of p42.3 in gastric cancers, immunohistochemistry and western blot were performed to detect the p42.3 expression in human GC tissues and cells. We also investigated the role of p42.3 in GC cell proliferation, migration, and invasion. Our results showed that the p42.3 expression was increased dramatically in human GC tissue and cells. In addition, we found that overexpression of p42.3 promotes GC cell proliferation, migration, and invasion abilities. Furthermore, p42.3 expression suppressed the E-cadherin protein level and promoted the ß-catenin and p-ERK protein level. Taken together, overexpressed p42.3 is correlated with gastric cancer cell proliferation, migration, and invasion, suggesting its use as a biological marker in gastric cancer.

Cell cycle-dependent expression of p42.3 promotes mitotic progression in malignant transformed cells.

In an earlier study, we cloned the p42.3 gene and showed that its expression was specific to tumors in a number of tumor cell lines and primary tumor tissues. However, the biological role and function of this gene remains largely unknown. In this study, p42.3 expression was found to be cell cycle-dependent at both the mRNA and protein levels in several human tumor cell lines. Typically, abundant expression was detected at G1 and M phases compared with S and G2 phases. Expression peaked at early G1 phase then decreased drastically at late G1, S, and G2. Furthermore, transfection of the p42.3 gene into NIH3T3 cells promoted malignant transformation, accompanied by accelerated mitotic progression and altered chromosome segregation. It was also observed that Cyclin B1 was upregulated and Cdc2-Tyr15 was downregulated following p42.3 overexpression in NIH3T3 cells. Combined, these results indicate that p42.3 as a cell cycle-regulated gene contributes to promoting cell cycle progression through disruption of mitotic regulation, and may play important roles in malignant transformation.

The Function and Regulation of SAPCD2 in Physiological and Oncogenic Processes.

The Suppressor APC Domain Containing 2 (SAPCD2) gene, also known by its aliases p42.3 and c9orf140, encodes a protein with an approximate molecular weight of 42.3 kDa. It was initially recognized as a cell cycle-associated protein involved in mitotic progression. Since the initial discovery of this gene, emerging evidence has suggested that its functions extend beyond that of regulating cell cycle progression to include modulation of planar polarization of cell progenitors and determination of cell fate throughout embryonic development. The underlying mechanisms driving such functions have been partially elucidated. However, the detailed mechanisms of action remain to be further characterized. The expression level of SAPCD2 is high throughout embryogenesis but is generally absent in healthy postnatal tissues, with restored expression in adult tissues being associated with various disease states. The pathological consequences of its aberrant expression have been investigated, most notably in the development of several types of cancers. The role of SAPCD2 in tumorigenesis has been supported by in vitro, in vivo, and retrospective clinical investigations and the mechanisms underlying its oncogenic function have been partially revealed. The potential of SAPCD2 as a diagnostic marker and therapeutic target of cancers have also been explored and have shown great promise. However, many questions pertaining to its oncogenic mechanisms as well as its value as a diagnostic marker and therapeutic target remain to be answered. In addition to its function as an oncogene, an involvement of SAPCD2 in other pathological processes such as inflammation has also been implicated and provides additional directions that warrant future investigation. This article reviews the current understanding of the normal cellular functions of SAPCD2 and the relevance of SAPCD2 in disease development with a primary focus on tumorigenesis. The mechanisms that regulate p43.2 expression, including the potential role of microRNAs in regulating its expression, are also reviewed. To the best of our knowledge, we are the first to comprehensively review the published findings regarding the physiological and pathological functions of this gene.

Expression of p42.3 in non-small cell lung cancer.

BACKGROUND: Lung cancer is the most malignant tumor with the highest morbidity and mortality. This study aimed to investigate the role of the expression and the significance of the p42.3 gene in non-small cell lung cancer (NSCLC). METHODS: Lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) were analyzed based on the biological information data of The Cancer Genome Atlas (TCGA). Furthermore, 142 postoperative tumor tissue and normal tissue samples (70 cases of LUAD and 72 cases of LUSC) from NSCLC patients admitted to our hospital from 2005 to 2009 were retrospectively collected. Paraffin-embedded tissues were used to make the tissue microarrays (TMA), and the expression of the p42.3 protein was detected by immunohistochemical staining. RESULTS: The expression of p42.3 in both LUAD and LUSC was significantly upregulated (P<0.01) compared with the normal lung tissues. The p42.3 expression was significantly higher than that of LUAD (P<0.01) in the LUSC group. LUSC had a lower level of p42.3 DNA methylation and a higher level of p42.3 DNA amplification than LUAD. The expression rate of p42.3 protein decreased in patients 70 years or older (P=0.029). High expression of the p42.3 protein was an independent factor for worse pathological differentiation (P=0.043). CONCLUSIONS: Both genetic and epigenetic alterations contributed to dysregulated p42.3 in NSCLC. Despite the temporary absence of TCGA-LUSC (TCGA data on LUSC) survival information, we observed that the up-regulated expression of p42.3 in LUSC was significantly higher than that in LUAD by analyzing the public database and reviewing the real-world data. Furthermore, a high expression of p42.3 protein was significantly correlated with poor differentiation of tumor tissues. Therefore, the prognostic value of p42.3 in LUSC deserves further study.

Depletion of p42.3 gene inhibits proliferation and invasion in melanoma cells.

PURPOSE: The p42.3 gene is identified recently, and the upregulated expression has been characterized in a variety of human cancers and embryonic tissues but not yet in malignant melanoma. In this study, we explored the role of p42.3 gene in the development of melanoma. METHODS: The expression of p42.3 was detected by immunohistochemistry staining of 261 cases of patient lesions, including nevi and melanoma, and its correlation with clinical pathological characteristics and prognosis was analyzed. Furthermore, a series of in vitro assays were used to investigate the biological function of p42.3 in melanoma cells. RESULTS: Immunohistochemistry staining showed an elevated expression level of p42.3 in melanoma compared to nevi (P = 0.001). Statistical analysis indicated that this high level was well correlated with patients' clinical stage (P = 0.045), but not with gender, age, clinical type, mitotic rate, and overall survival (P > 0.05). Moreover, in vitro assays showed knockdown p42.3 gene expression could inhibit the biological profiling, including proliferation, migration, and invasion of melanoma cells, and also affect PI3K/Akt pathway, MAPK pathway, and ß-catenin. CONCLUSIONS: This study suggests that p42.3, acting like an oncogene, is involved in the malignant transformation process of melanoma and may serve as a biomarker for diagnostic and treatment purposes.

Establishment of optimal regulatory network of colorectal cancer based on p42.3 protein.

Objective: to establish regulatory network of colorectal cancer involving p42.3 protein and to provide theoretical evidence for deep functional exploration of p42.3 protein in the onset and development of colorectal cancer. Methods: with protein similarity algorithm, reference protein set of p42.3 cell apoptosis was built according to structural features of p42.3. GO and KEGG databases were used to establish regulatory network of tumor cell apoptosis involving p42.3; meanwhile, the largest possible working pathway that involves p42.3 protein was screened out based on Bayesian network theory. Besides, GO and KEGG were used to build regulatory network on early diagnosis gene markers for colorectal cancer including WWOX, K-ras, COX-2, p53, APC, DCC and PTEN, at the same time, a regulatory network of colorectal cancer cell apoptosis which involves p42.3 was established. Results: cell apoptotic regulatory network that p42.3 participates in primarily consists of Bcl-2 family genes and the largest possible pathway is p42.3 → FKBP → Bcl-2 centered as FKBP protein. Combined with colorectal cancer regulatory network that involves early diagnosis gene markers, it can be predicted that p42.3 is most likely to regulate the colorectal cancer cell apoptosis through FKBP → Bcl-2 → Bax → caspase-9 → caspase-3 pathway. Conclusion: the colorectal cancer apoptosis network based on p42.3 established in the study provides theoretical evidence for deep exploration of p42.3 regulatory mechanism and molecular targeting treatment of colorectal cancer.

Positive relationship between p42.3 gene and inflammation in chronic non-atrophic gastritis.

OBJECTIVE: Gastric cancer (GC) is a typical type of inflammation-related tumor. The p42.3 gene is shown to be highly expressed in GC, but its association with gastritis remains unknown. We aimed to explore the relationship between gastric inflammation and p42.3 gene in vitro and in vivo. METHODS: Normal gastric epithelial cells (GES-1) were treated with Helicobacter pylori (H. pylori) and tumor necrosis factor (TNF)-α. Total cell mRNA and protein were extracted and collected, and polymerase chain reaction and Western blot were performed to determine the relative expression of p42.3 gene. In total, 291 biopsy samples from patients with chronic non-atrophic gastritis were collected and immunohistochemistry was used to measure the p42.3 protein expression. The association between p42.3 protein expression and the clinicopathological characteristics of these patients were analyzed. RESULTS: Both H. pylori and TNF-α significantly enhanced the p42.3 protein expression in GES-1 cells in a time and dose-dependent manner. In addition, p42.3 gene expression was positively associated with the severity of gastric mucosal inflammation and H. pylori infection (P = 0.000). Its expression was significantly more common in severe gastric inflammation and in H. pylori-infected cases. CONCLUSION: p42.3 gene expression is associated with gastric mucosal inflammation that can be upregulated by TNF-α and H. pylori infection.

p42.3 promotes cell proliferation and invasion in human Renal-Cell Carcinoma.

p42.3 is a tumor-specific gene and found to be over-expressed in many tumor cell lines and primary tumor tissues. It plays a significant role in neoplastic transformation and tumor progression. To date, the association between p42.3 and Renal-Cell Carcinoma (RCC) has not been reported. This study investigated the biological effects and mechanisms of p42.3 in RCC progression. In this study, we found that p42.3 is overexpressed in various kinds of RCC cells, and knockdown of p42.3 dramatically reduced cell proliferation and invasion in vitro. Our studies revealed that overexpression of p42.3 accelerates the epithelial-mesenchymal transition (EMT) progression and induces RCC cells proliferation and invasion. Further studies show that p42.3 may involve in activation of ß-catenin and participate in RCC cell invasion. Combined, these data indicate that p42.3 contributes to promoting RCC cells proliferation and invasion through accelerates the EMT progression and ß-catenin activation.

Overexpression of p42.3 promotes cell growth and tumorigenicity in hepatocellular carcinoma.

AIM: To investigate the association of p42.3 expression with clinicopathological characteristics and the biological function of p42.3 in human hepatocellular carcinoma (HCC). METHODS: We used reverse transcription-polymerase chain reaction (RT-PCR), quantitative real-time RT-PCR and western blotting to detect p42.3 mRNA and protein expression in hepatic cell lines. We examined primary HCC samples and matched adjacent normal tissue by immunohistochemistry to investigate the correlation between p42.3 expression and clinicopathological features. HepG2 cells were transfected with a pIRES2-EGFP-p42.3 expression vector to examine the function of the p42.3 gene. Transfected cells were analyzed for their viability and malignant transformation abilities by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, colony formation assay, and tumorigenicity assay in nude mice. RESULTS: p42.3 is differentially expressed in primary HCC tumors and cell lines. Approximately 69.6% (96/138) of cells were p42.3-positive in hepatic tumor tissues, while 30.7% (35/114) were p42.3-positive in tumor-adjacent normal tissues. Clinicopathological characteristics of the HCC specimens revealed a significant correlation between p42.3 expression and tumor differentiation (P = 0.031). However, p42.3 positivity was not related to tumor tumor-node-metastasis classification, hepatitis B virus status, or hepatoma type. Regarding p42.3 overexpression in stably transfected HepG2 cells, we discovered significant enhancement of cancer cell growth and colony formation in vitro, and significantly enhanced tumorigenicity in nude mice. Western blot analysis of cell cycle proteins revealed that enhanced p42.3 levels promote upregulation of proliferating cell nuclear antigen, cyclin B1 and mitotic arrest deficient 2. CONCLUSION: p42.3 promotes tumorigenicity and tumor growth in HCC and may be a potential target for future clinical cancer therapeutics.

A DNA vaccine targeting p42.3 induces protective antitumor immunity via eliciting cytotoxic CD8+T lymphocytes in a murine melanoma model.

The p42.3 gene was recently identified and characterized as having tumor-specific and mitosis phase-dependent expression in many types of cancer. This suggested that p42.3 antigen could be used as a target for vaccines against cancers. In this study, we immunized C57BL/6 mice with a DNA vaccine encoding p42.3. We used intramuscular injection with electroporation, either before or after challenge with tumor B16F10 cells. Vaccination with pcDNA3-p42.3 induced some degree of antitumor effect both therapeutically and prophylactically, as evaluated by the inhibition of tumor growth and decrease in tumor weight. Immunized mice showed a high level of specific cytotoxic activity against the p42.3 protein in vivo and had activated CD8 T cells that secreted IFN-γ, perforin, and granzyme B in response to stimulation with the antigen in vitro. Thus, this study presents the DNA vaccination against novel tumor target p42.3 as a promising antitumor modality.