Ornithine decarboxylase and glutamate decarboxylase 65 as prognostic markers of gallbladder malignancy: a clinicopathological study in benign and malignant lesions of the gallbladder. Mol Med Rep. 2013;7:413-418. [PMID: 23152127 DOI: 10.3892/mmr.2012.1178]

GAD2 Is a Highly Specific Marker for Neuroendocrine Neoplasms of the Pancreas

Glutamate decarboxylase 2 (GAD2) is the most important inhibitory neurotransmitter and plays a role in insulin-producing β cells of pancreatic islets. The limitation of GAD2 expression to a few normal cell types makes GAD2 a potential immunohistochemical diagnostic marker. To evaluate the diagnostic utility of GAD2 immunohistochemistry, a tissue microarray containing 19,202 samples from 152 different tumor entities and 608 samples of 76 different normal tissue types was analyzed. In normal tissues, GAD2 staining was restricted to brain and pancreatic islet cells. GAD2 staining was seen in 20 (13.2%) of 152 tumor categories, including 5 (3.3%) tumor categories containing at least 1 strongly positive case. GAD2 immunostaining was most commonly seen in neuroendocrine carcinomas (58.3%) and neuroendocrine tumors (63.2%) of the pancreas, followed by granular cell tumors (37.0%) and neuroendocrine tumors of the lung (11.1%). GAD2 was only occasionally (<10% of cases) seen in 16 other tumor entities including paraganglioma, medullary thyroid carcinoma, and small cell neuroendocrine carcinoma of the urinary bladder. Data on GAD2 and progesterone receptor (PR) expression (from a previous study) were available for 95 pancreatic and 380 extrapancreatic neuroendocrine neoplasms. For determining a pancreatic origin of a neuroendocrine neoplasm, the sensitivity of GAD2 was 64.2% and specificity 96.3%, while the sensitivity of PR was 56.8% and specificity 92.6%. The combination of PR and GAD2 increased both sensitivity and specificity. GAD2 immunohistochemistry is a highly useful diagnostic tool for the identification of pancreatic origin in case of neuroendocrine neoplasms with unknown site of origin.

Effect of CEACAM6 silencing on the biological behavior of human gallbladder cancer cells

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is abnormally expressed in various malignant tumors and thus represents a potential biomarker, although information regarding its role in gallbladder cancer (GBC) is limited. This study aimed to evaluate the expression of CEACAM6 in GBC and the effect of CEACAM6 gene silencing on the proliferation, migration, invasion and apoptosis of human GBC cells. Immunochemistry was used to evaluate CEACAM6 expression in 95 GBC specimens and 40 peritumoral tissue specimens. GBC-SD and SGC-996 cell lines were used for in vitro experiments. CEACAM6 was knocked down by transfection of targeted small interfering RNA (siRNA), and reverse-transcription quantitative PCR and western blot analysis were used to detect knockdown efficiency. Cell Counting Kit-8 and colony formation assays were undertaken to evaluate cell proliferation. Variations in cell migration and invasion were detected by wound-healing and Transwell assays, respectively. Flow cytometry was applied to measure cell apoptosis and cell cycle distribution. CEACAM6 gene expression was significantly greater in GBC tissues than in peritumoral tissues, and its positive expression was associated with poor prognosis. CEACAM6 mRNA and protein expression in the CEACAM6 siRNA treatment group was significantly lower than that in the negative control group and the blank group. CEACAM6 knockdown inhibited GBC cell proliferation, migration and invasion but promoted cell apoptosis. Western blot analysis of invasion- and apoptosis-related proteins matrix metalloproteinase-2, Vimentin, BCL-2 and BAX further confirmed CEACAM6 mRNA depletion promoted cell apoptosis and inhibited invasion. Additionally, CEACAM6 mRNA depletion affected the progression of the GBC cell cycle to increase cell distribution in G₀/G₁ phase, and to reduce it in G₂/M phase and S phase. These findings indicated that CEACAM6 overexpression may be related to the tumorigenesis and development of GBC. In summary, depletion of CEACAM6 mRNA suppressed the malignant biological behaviors of human gallbladder cancer cells.

Ornithine decarboxylase inhibition downregulates multiple pathways involved in the formation of precancerous lesions of esophageal squamous cell cancer

The high incidence and mortality of esophageal squamous cell cancer (ESCC) is a major health problem worldwide. Precancerous lesions of ESCC may either progress to cancer or revert to normal epithelium with appropriate interventions; the bidirectional instability of the precancerous lesions of ESCC provides opportunities for intervention. Reports suggest that the upregulation of ornithine decarboxylase (ODC) is closely related to carcinogenesis. In this study, we investigated whether ODC may act as a target for chemoprevention in ESCC. Immunohistochemistry (IHC) assays indicate that ODC expression is higher in esophageal precancerous lesions compared with normal tissue controls. Its overexpression promotes cell proliferation and transformation of normal esophageal epithelial cells, and its activity is increased after N-nitrosomethylbenzylamine (NMBA) induction in Shantou human embryonic esophageal cell line (SHEE) and human immortalized cells (Het1A) cells. In addition, p38 α, extracellular regulated kinase (ERK1/2) in the mitogen-activated protein kinase pathway and protein kinase B (AKT)/mammalian target of rapamycin (mTOR)/ribosomal protein S6 kinase (p70S6K) pathways are activated in response to NMBA treatment. Difluoromethylornithine (DFMO) is an ODC inhibitor, which inhibits NMBA-induced activation of p38 α, ERK1/2 and AKT/mTOR/p70S6K pathways; this has been verified by Western blotting. DFMO was also found to suppress the development of esophageal precancerous lesions in an NMBA-induced rat model; IHC demonstrated p38 α, ERK1/2, and AKT/mTOR/p70S6K pathways to be downregulated in these rats. These findings indicate the mechanisms by which ODC inhibition suppresses the development of esophageal precancerous lesions by downregulating p38 α, ERK1/2, and AKT/mTOR/p70S6k signaling pathways, ODC may be a potential target for chemoprevention in ESCC.

Gallbladder cancer epidemiology, pathogenesis and molecular genetics: Recent update

Gallbladder cancer is a malignancy of biliary tract which is infrequent in developed countries but common in some specific geographical regions of developing countries. Late diagnosis and deprived prognosis are major problems for treatment of gallbladder carcinoma. The dramatic associations of this orphan cancer with various genetic and environmental factors are responsible for its poorly defined pathogenesis. An understanding to the relationship between epidemiology, molecular genetics and pathogenesis of gallbladder cancer can add new insights to its undetermined pathophysiology. Present review article provides a recent update regarding epidemiology, pathogenesis, and molecular genetics of gallbladder cancer. We systematically reviewed published literature on gallbladder cancer from online search engine PubMed (http://www.ncbi.nlm.nih.gov/pubmed). Various keywords used for retrieval of articles were Gallbladder, cancer Epidemiology, molecular genetics and bullion operators like AND, OR, NOT. Cross references were manually searched from various online search engines (http://www.ncbi.nlm.nih.gov/pubmed,https://scholar.google.co.in/, http://www.medline.com/home.jsp). Most of the articles published from 1982 to 2015 in peer reviewed journals have been included in this review.

Association between the ornithine decarboxylase G316A polymorphism and breast cancer survival

Ornithine decarboxylase (ODC) is a significant rate-limiting enzyme in polyamine synthesis, required for normal cell growth, and is highly expressed in various malignancies, including colorectal and breast cancer. In the present study, the associations between the ODC G316A single nucleotide polymorphism (SNP) and breast cancer-specific survival were investigated. In addition, the functional effects of this SNP were examined in the MCF-7 human breast cancer cell line. The present study recruited 300 stage I-III breast cancer cases, which were diagnosed at the Affiliated Cancer Hospital of Zhengzhou University (Zhengzhou, China) between 2002 and 2003, with follow-up visits conducted until May 2013. ODC G316A was genotyped (ODC GG vs. ODC AG/AA) in the 300 cases and the association of the genotypes with cancer-specific survival was analyzed. In the MCF-7 cell line, the ODC allele-specific binding of E-box transcription factors was determined using western blot and chromatin immunoprecipitation assays. Survival differences were observed between the two genotypes: Compared with the ODC GG genotype, patients with ODC GA/AA exhibited significantly higher survival rates (P<0.05). In cultured cells, the ODC SNP, which is flanked by two E-boxes, appeared to predict ODC promoter activity. Furthermore, the E-box activator c-MYC and repressor MAX interactor 1 were found to preferentially bind to ODC minor A-alleles compared with major G-alleles, in cultured MCF-7 cells. In conclusion, the results of the current study suggest that the regulation of ODC may affect survival in breast cancer patients and indicate a model in which the ODC SNP may be protective for breast adenoma recurrence and detrimental for survival following a diagnosis of breast cancer.

The role of glutamate decarboxylase 65 in gastric cancer development, progression, and prognosis

AIMS

Recent studies have revealed that glutamate decarboxylase 65 (GAD65) plays important roles in cancer progression. The role of GAD65 in gastric cancer development, progression and prognosis is currently unknown, and we aimed to investigate this.

METHODS AND RESULTS

Immunohistochemistry revealed that GAD65 expression in 313 gastric cancer tissues was significantly higher than in 60 adjacent non-tumour tissues. Moreover, the expression level of GAD65 significantly correlated with the depth of tumour invasion and TNM stage. GAD65 expression level was a significant prognostic factor in univariate survival analysis, but did not remain an independent prognostic factor following Cox multivariate analysis. For tumours with an intermediate type growth pattern, when those showing low expression of GAD65 were reclassified with expanding type tumours, and those showing high expression with infiltrative type tumours, there was a significant difference in prognosis between these two novel subgroups, and this remained a significant prognostic factor in multivariate analysis.

CONCLUSIONS

Our findings indicate that GAD65 is involved in the development and progression of gastric cancer as a tumour oncoprotein. Further elucidation of the molecular mechanisms underlying the role of GAD65 is warranted.