Prognostic significance of p21WAF1/CIP1, p27Kip1, p53 and E-cadherin expression in gastric cancer

Application of serum gastric function markers and digestive tumor indices to the diagnosis of early gastric cancer and precancerous lesions

OBJECTIVES

To study the levels of carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 199, CA724, CA242, pepsinogen (PG) I, PGII, gastrin-17 (G-17), the PGI/PGII ratio (PGR), as well as the expression of p27 and Ki67, in patients suffering from early gastric cancer and intraepithelial neoplasia and to provide new markers for the diagnosis of early gastric cancer and precancerous lesions.

METHODS

A retrospective study where the blood serum concentration of CEA, CA199, CA724, CA242, PGI, PGII, G-17 and PGR were tested and also the protein expression of p27 and Ki67 was detected in patients tissues by immunohistochemistry in the Gastrointestinal Endoscopy Center of the Affiliated Hospital of Xuzhou Medical University, Xuzhou, China, from March 2018 to March 2021.

RESULTS

Carbohydrate antigen 242 and CA199 levels in tumor tissue significantly differed among the groups. Pepsinogen I levels decreased with increasing disease severity, G-17 levels increased with the aggravation of severity, and p27 expression decreased with the severity.

CONCLUSION

The combination of serum gastric function markers (PGI and G-17) and p27 digestive tumor indices can serve as markers for the diagnosis of early gastric cancer and intraepithelial neoplasia.

The Role of P21 Protein Expression in Predicting Progression and Biological Behaviors of Gastric Adenocarcinomas

Background: P21 protein is a cyclin-dependent kinase inhibitor and has a crucial function as a cell cycle regulator in malignant tissues. Thus, its association with aggressive characteristics of malignant lesions is suggested. Objectives: We evaluated the expression level of P21 in gastric cancers and its association with the histopathological findings of cancer. Methods: This cross-sectional study was performed on gastric adenocarcinomas from radical gastrectomy. The histopathological examination was assessed by Hematoxylin & Eosin. The immunohistochemistry technique was then used to assess the expression of the P21 marker. Results: P21 positivity was revealed in 28 specimens of the cancerous lesions with an overall prevalence of 70.0% in our population. There was no association between P21 positivity and tumor-related characteristics, including tumor location, type, grade and stage, as well as the size of the cancerous lesion. P21 positivity could not be related to perineural or lymphovascular invasion of the tumor (P-value > 0.05). Conclusions: In our population, the expression of P21 may not be prognostic or predict tumor biological behavior among patients with gastric adenocarcinomas.

Signaling pathways of oxidative stress response: the potential therapeutic targets in gastric cancer

Gastric cancer is one of the top causes of cancer-related death globally. Although novel treatment strategies have been developed, attempts to eradicate gastric cancer have been proven insufficient. Oxidative stress is continually produced and continually present in the human body. Increasing evidences show that oxidative stress contributes significantly to the development of gastric cancer, either through initiation, promotion, and progression of cancer cells or causing cell death. As a result, the purpose of this article is to review the role of oxidative stress response and the subsequent signaling pathways as well as potential oxidative stress-related therapeutic targets in gastric cancer. Understanding the pathophysiology of gastric cancer and developing new therapies for gastric cancer depends on more researches focusing on the potential contributors to oxidative stress and gastric carcinogenesis.

Cyclin-dependent kinase inhibitors in malignant hematopoiesis

The cell-cycle is a tightly orchestrated process where sequential steps guarantee cellular growth linked to a correct DNA replication. The entire cell division is controlled by cyclin-dependent kinases (CDKs). CDK activation is balanced by the activating cyclins and CDK inhibitors whose correct expression, accumulation and degradation schedule the time-flow through the cell cycle phases. Dysregulation of the cell cycle regulatory proteins causes the loss of a controlled cell division and is inevitably linked to neoplastic transformation. Due to their function as cell-cycle brakes, CDK inhibitors are considered as tumor suppressors. The CDK inhibitors p16^INK4a and p15^INK4b are among the most frequently altered genes in cancer, including hematopoietic malignancies. Aberrant cell cycle regulation in hematopoietic stem cells (HSCs) bears severe consequences on hematopoiesis and provokes hematological disorders with a broad array of symptoms. In this review, we focus on the importance and prevalence of deregulated CDK inhibitors in hematological malignancies.

Clinicopathological significance and prognostic value of P27 expression in gastric cancer patients: a meta-analysis

Loss of P27 expression correlates with clinical progression in a variety of human cancers. However, the correlation between P27 expression and gastric cancer remains controversial. In this meta-analysis, we performed an electronic search based on six databases to select a sufficient number of studies. Pooled hazard ratio (HR) was used as estimates to investigate the association between P27 expression and prognosis of patients with gastric cancer. We identified 19 studies with 2387 gastric cancer patients, ranging between 50 and 316 samples per study. Q and I2 tests demonstrated that the homogeneity among 19 studies (I2 = 47%, P = 0.0004), thus we applied a fixed-effects model to calculate the pooled HR of P27expression and overall survival (OS) of gastric cancer patients was 0.68, and 95% confidence interval (CI) was 0.60-0.78. Next, we conducted a subgroup meta-analysis and found that patients with low P27 expression in Asians (HR = 0.69, 95% CI: 0.58-0.82) and non-Asians (HR = 0.57, 95% CI: 0.41-0.79) had poor prognosis. In addition, we found the publication bias results of OS in the final included 19 studies showed that this funnel plot presented incomplete symmetry, and then removed three literatures with larger HRs bias, and found that the remaining 16 literatures were homogeneity (I2 = 0%, P = 0.47), the pooled HR was 0.52 with 95% CI of 0.43-0.62, and the publication bias disappeared. These results suggested a strong association between P27 underexpression and poorer prognosis of gastric cancer in patients. P27 may be a tumor suppressor for predicting survival outcome of gastric cancer patients.

Typical and Atypical Carcinoid Tumors of the Mediastinum: A Biomarker Analysis of 27 Cases With Clinical Correlation

Thymic typical and atypical carcinoids are rare and appear to be more aggressive than similar tumors in other sites. We retrospectively analyzed a group of biomarkers that hold therapeutic and prognostic utility, in 27 of these tumors. All cases were immunohistochemically stained with PAX5, MET, CRMP5, paxillin, p21, p27, EZH2, PDL-1, and Ki-67, and then H-scored. Clinicopathologic and survival data were statistically analyzed against staining (χ² test). Five- and 10-year-survival rates were 53% and 18%, respectively. Mitotic counts ≥4 per 2 mm² and tumor size ≥5 cm, associated with death of disease (DoD; P = .010 and .016). Ki-67 expression ≥1% associated with DoD (P = .003) and death within 5 years (P = .031). Biomarkers stained tumor cases as follows: PDL-1 = 0%, PAX-5 = 0%, MET = 7.4%, paxillin = 41%, CRMP5 = 78%, p21 = 63%, p27 = 63%, EZH2 = 37%, and MASH1 = 59%. Overall ± staining did not associate with survival or grade. Cases with low CRMP5 H-scores (<80) associated with DoD (P = .002), while CRMP5 H-scores >80 associated with 10-year survival (P = .022). Cases with high MASH1 H-score (>100) associated with DoD (P = .021). Accurate grading and staging remain paramount in predicting clinical outcome. Biomarkers may have significance in subsets of patients and the use of these studies likely should be focused on a more personalize type of approach.

Expression of p27 and p16 and their clinical significance in gastric cancer

BACKGROUND

Deregulated expression of cell cycle regulators p27 and p16 is associated with cancer progression. p27^kip1 and p16^INKa are a cyclin dependent kinase inhibitor whose major target is the cyclinE/CDK2 and cyclinD/CDK4/6 complex, respectively, that governs cell cycle transition from late G1 to S phase.

METHODS

We recruited biopsies of a total of 84 subjects including 72 primary tumor biopsies from histopathologically proven gastric carcinoma, 8 adjacent controls and 12 independent controls. We used gastric cancer cell line, AGS, for validation of our data. Expression profiling at transcript level was done by semi-quantitative RT-PCR and at proteome level by immunohistochemistry and immunofluorescence. Receiver operator characteristics analysis was done for determining the diagnostic utility of p27 and p16 with respect to the sensitivity and specificity.

RESULTS

We demonstrate that p27 and p16 are frequently over expressed in early stages of gastric carcinoma. Our semi-quantitative data show a significant upregulation of p27 (Mean ± SEM, 0.4771 ± 0.0895; p = 0.0001) and p16 (Mean ± SEM, 0.4676 ± 0.04305; p = 0.0001) at mRNA level. Concordant to semi-quantitative data, immunohistochemistry data also showed a significant upregulation of p27 (Mean ± SEM, 196.4 ± 10.84; p < 0.0001) and p16 (Mean ± SEM, 100.4 ± 23.71; p < 0.0001) at protein level.

CONCLUSIONS

The present study showed that the significant upregulation of p27 and p16 were associated with early events in gastric carcinogenesis. Our data suggests that clinical correlation of these differentially expressed genes may be useful as diagnostic biomarkers for early detection of gastric carcinoma and promising therapeutics target for GC patients.

The role of E-cadherin and Runx3 in Helicobacter Pylori - Associated gastric carcinoma is achieved through regulating P21waf and P27 expression

BACKGROUND

We assessed the role of E-cadherin (CDH1), runt-related transcription factor 3, p21waf and p27 promoter methylation (PM) and protein expression in Helicobacter pylori (HP)-associated gastric carcinomas (GCs) and adjacent non-neoplastic tissues (ANNTs).

PATIENTS AND METHODS

192 cases were assessed for PM and protein expression of CDH1, RUNX3, p21waf and p27 by methylation-specific PCR (MSP) and immunohistochemistry. The CagA gene was also assessed.

RESULTS

In GCs, 66 (34.4%) and 84 (43.8%) cases showed CDH1-PM and reduced expression. It is significantly affected in GCs rather than in non-neoplastic groups (p < 0.001). In ANNTs, 108 (56.3%) cases showed CDH1-PM and all cases revealed preserved protein expression. RUNX3-PM was detected in 78 GCs (40.6%) and 69 ANNTs (35.9%), whereas reduced protein expression was detected in 99 (51.65%) GC compared to ANNTs 90 (46.9%). p21WAF and p27 showed PM in (48.4% and 45.3%) GCs and ANNTs; respectively. p21waf protein was reduced in 90 (46.9%) cases and 91 ANNTs (47.4%). p27 was reduced in 86 (44.8%) cases and 87 ANNTs (45.3%). CDH1 aberrations correlated with HP in tumors and ANNTs and with diffuse/intestinal tumors (p = 0.014, p = 0.014 and p = 0.02). RUNX3 aberrations associated with HP (p = 0.04), high grade (p = 0.04), and advanced stage (p = 032). Tumor grade associated with RUNX3-PM, CDH, p21 and p27 protein (p < 0.05 for all). Tumor stage associated significantly with PM and reduced protein expression of all markers. Positive lymph nodes associated significantly with p27PM (p < 0.001).

CONCLUSIONS

HP plays an important role in the development and progression of GC through silencing of CDH1, RUNX3, p21WAF and p27 expression.

Molecular Signaling in Tumorigenesis of Gastric Cancer

Gastric cancer (GC) is regarded as the fifth most common cancer and the third cause of cancer-related deaths worldwide. Mechanism of GC pathogenesis is still unclear and relies on multiple factors, including environmental and genetic characteristics. One of the most important environmental factors of GC occurrence is infection with Helicobacter pylori that is classified as class one carcinogens. Dysregulation of several genes and pathways play an essential role during gastric carcinogenesis. Dysregulation of developmental pathways such as Wnt/β-catenin signaling, Hedgehog signaling, Hippo pathway, Notch signaling, nuclear factor-kB, and epidermal growth factor receptor have been found in GC. Epithelial-mesenchymal transition, as an important process during embryogenesis and tumorigenesis, is supposed to play a role in initiation, invasion, metastasis, and progression of GC. Although surgery is the main therapeutic modality of the disease, the understanding of biological processes of cell signaling pathways may help to develop new therapeutic targets for GC.

Characterization of oncogene suppressor marker expression in patients with submucosal gastric carcinoma

The aim of the present study was to determine the clinical significance of p53 and p21^ras p21^wafl, p27^kip1 and p16^ink4a expression in cases of early gastric cancer. A total of 81 patients who had undergone gastrectomy with D2 lymphadenectomy between 1971 and 2004 were retrospectively investigated. The immunohistochemical expression of p21^ras, p53, p21^waf1/cip1, p27^kip1 and p16^ink4a in the tissues was evaluated. In normal, metaplastic and tumoral mucosa, p53 was positive in 53, 87.3, and 87.1% of the cases, respectively. In the same tissues, p21^ras was positivE in 85.3, 86 and 96.8%, respectively. Positivity FOR p16^ink4a was DETECTED IN 46.3, 91.1 and 86% OF THE CASES, respectively, WHEREAS p27^kip1 WAS positiVE IN 60, 94.7 and 95.3%, and p21^wafl/cip1 WAS positivE IN 32.4, 72.7 and 71.4% OF THE CASES, respectively. All THE tumors WERE positive for p53. Tumors with lymph node invasion presented WITH OVERexpression (+4) of p53 in 47% of the cases VS. 17% OF patients who DID not HAVE lymph node involvement. THEREFORE, higher expression of p53, p21^ras and p21^wafl/cip1 IN the tumor exhibited a statistically significant association with lymph node involvement.

Clinical significances of p27 in digestive tract cancers: a comprehensive analysis on immunohistochemistry staining, published literatures, microarray and RNA-seq data

In the present study, we conducted a comprehensive analysis on the clinical roles of p27 protein and p27 gene in digestive tract cancers (DTCs). First, we performed immunohistochemistry staining and found that p27 protein was down-regulated in DTCs. Then we collected 62 publications and calculated the combined hazard ratios (HRs), odds ratios (ORs) and 95% confidence intervals (95% CIs) to clarify the relationships of p27 protein expression with prognoses and clinicopathological parameters. The overall HRs indicated that the down-regulated p27 protein was an independent prognostic biomarker for overall survival (HR: 1.58, 95% CI: 1.38-1.81, P < 0.0001) but not for disease-free survival and cancer-specific survival. The combined ORs indicated that a low expression of p27 protein was positively related to lymph node metastasis (OR: 2.15, 95% CI: 1.57-2.96, P < 0.0001), distant metastasis (OR: 2.02, 95% CI: 1.12-3.63, P = 0.019) and pathology grading (OR: 2.14, 95% CI: 1.75-2.62, P < 0.0001). Additionally, 60 DTCs-related microarray and RNA-seq datasets were obtained to investigate the expression level and clinical value of p27 gene in DTCs patients. We found that the expression level of p27 gene in DTCs was similar to that in normal controls. And no significant associations of p27 gene expression with prognoses and clinicopathological factors were observed. In conclusion, according to our results, it was p27 protein, but not p27 gene, that can function as an effective biomarker to predict the clinical outcome in patients with DTCs. The down-regulation of p27 protein in DTCs may not result from the altered expression of p27 gene.

Poorly Differentiated Medullary Phenotype Predicts Poor Survival in Early Lymph Node-Negative Gastro-Esophageal Adenocarcinomas

BACKGROUND

5-year survival rate in patients with early adenocarcinoma of the gastro-esophageal junction or stomach (AGE/S) in Caucasian patients is reported to be 60-80%. We aimed to identify prognostic markers for patients with UICC-I without lymph-node involvement (N0).

METHODS

Clinical data and tissue specimen from patients with AGE/S stage UICC-I-N0, treated by surgery only, were collected retrospectively. Tumor size, lymphatic vessel or vein invasion, grading, classification systems (WHO, Lauren, Ming), expression of BAX, BCL-2, CDX2, Cyclin E, E-cadherin, Ki-67, TP53, TP21, SHH, Survivin, HIF1A, TROP2 and mismatch repair deficiency were analyzed using tissue microarrays and correlated with overall and tumor related survival.

RESULTS

129 patients (48 female) with a mean follow-up of 129.1 months were identified. 5-year overall survival was 83.9%, 5-year tumor related survival was 95.1%. Poorly differentiated medullary cancer subtypes (p<0.001) and positive vein invasion (p<0.001) were identified as risk factors for decreased overall-and tumor related survival. Ki-67 (p = 0.012) and TP53 mutation (p = 0.044) were the only immunohistochemical markers associated with worse overall survival but did not reach significance for decreased tumor related survival.

CONCLUSION

In the presented study patients with AGE/S in stage UICC-I-N0 had a better prognosis as previously reported for Caucasian patients. Poorly differentiated medullary subtype was associated with reduced survival and should be considered when studying prognosis in these patients.

Genomic landscape of gastric cancer: molecular classification and potential targets

Gastric cancer imposes a considerable health burden worldwide, and its mortality ranks as the second highest for all types of cancers. The limited knowledge of the molecular mechanisms underlying gastric cancer tumorigenesis hinders the development of therapeutic strategies. However, ongoing collaborative sequencing efforts facilitate molecular classification and unveil the genomic landscape of gastric cancer. Several new drivers and tumorigenic pathways in gastric cancer, including chromatin remodeling genes, RhoA-related pathways, TP53 dysregulation, activation of receptor tyrosine kinases, stem cell pathways and abnormal DNA methylation, have been revealed. These newly identified genomic alterations await translation into clinical diagnosis and targeted therapies. Considering that loss-of-function mutations are intractable, synthetic lethality could be employed when discussing feasible therapeutic strategies. Although many challenges remain to be tackled, we are optimistic regarding improvements in the prognosis and treatment of gastric cancer in the near future.

The opposite prognostic significance of nuclear and cytoplasmic p21 expression in resectable gastric cancer patients

BACKGROUND

Protein p21(Cip1/Waf1) is a cyclin-dependent kinase inhibitor, which plays important roles in cell cycle arrest, senescence, and apoptosis. Interestingly, the nuclear and cytoplasmic p21 executes various functions in the cell. In this study, we investigated the prognostic impact of subcellular p21 expression in gastric cancer (GC).

METHODS

Expressions of subcellular p21 was assessed by immunohistochemistry using a tissue microarray in a training cohort and it went into a second testing cohort and finally to a validating cohort. Prognostic and predictive role of subcellular p21 expression status was evaluated. We also studied the roles of subcellular p21 in GC cell migration and invasion.

RESULTS

Nuclear and cytoplasmic p21 protein levels were significantly reduced and increased in GC lesions compared with adjacent non-cancerous tissues, respectively. Low nuclear p21 or high cytoplasmic p21 expression significantly correlated with shorter overall survival (OS), as well as with clinicopathologic characteristics in patients. Multivariate regression analysis showed that low nuclear and high cytoplasmic p21 expression, separately and together, were independent negative markers of OS. Finally, we found that nuclear p21 inhibits but cytoplasmic p21 promotes cell migration and invasion abilities.

CONCLUSIONS

These findings suggest that nuclear and cytoplasmic p21 protein expression in tumor are novel candidate prognostic markers in resectable human gastric carcinoma, and they exert distinct roles in cell migration and invasion.

Immunohistochemical expression of p27(kip1) in metastatic laryngeal squamous cell carcinoma

PURPOSE

Laryngeal squamous cell carcinoma (LSCC) is an interesting diagnostic and therapeutic issue. The diagnostic delay is mainly a consequence of the lack of evident symptoms in the early stage of the disease. The purpose of current studies was the evaluation of the expression of p27(kip1) in primary and metastatic LSCC in correlation with patients' clinicopathological data.

MATERIAL/METHODS

The indirect immunohistochemical studies were performed on the series of 60 sections (primary tumor: 20 cases of N(0) and 20 cases of N(+), and nodal meta: 20 cases), using primary antibody against p27(kip1) [clone 1B4]. The expression of analyzed protein was performed using automated morphometric methods.

RESULTS

The p27(kip1) nuclear expression was found in 100% (40/40) cases of primary tumor, and in 85% (17/20) cases of SCC meta at lymph nodes. In primary LSCC N(0) the expression of p27(kip1) was significantly higher compared to N(+) cases (p=0.036672). However, the p27(kip1) expression in SCC metastases was higher compared to the primary SCC. Moreover, the analyses based on the classification trees revealed the cutoff p27(kip1) expression in primary LSCC (IRS ≤ 76) which was characteristic for N(+) patients. Consequently, our analysis revealed that high expression of p27(kip1) (IRS>76) was characteristic for N(0) patients.

CONCLUSIONS

Our results suggest that p27(kip1) might be useful prognostic factor of metastatic potential in laryngeal squamous cell carcinoma.

Expression of CD24, p21, p53, and c-myc in alpha-fetoprotein-producing gastric cancer: Correlation with clinicopathologic characteristics and survival

BACKGROUND AND OBJECTIVE

The aim of this study was to evaluate the expression of CD24, p21, p53, and c-myc in lesions of patients with Alpha-Fetoprotein (AFP)-producing gastric cancer and their correlation with clinicopathological features and prognosis.

METHODS

One hundred and four patients with AFP-producing gastric cancer were included into this study. The levels of CD24, p21, p53, and c-myc were examined by immunohistochemistry.The prognostic value of these biological markers and the correlation between biological markers and clinicopathological factors were investigated.

RESULTS

The percentages of positive expression of CD24, p21, p53, and c-myc were 31.7%, 77.9%, 75.0%, and 66.3%, respectively. CD24 expression correlated with histological grade (P = 0.045) and Lauren type (P = 0.006); p21expression with Borrmann type (P = 0.035); c-myc expression with Borrmann type (P = 0.029). p21 expression was related with poor survival in univariate analysis (P = 0.016). Multivariate analysis showed that p21 expression, vascular invasion, and pathological stage were defined as independent prognostic factors.

CONCLUSION

The expression of p21 was an independent prognostic factor for patients with AFP-producing gastric cancer.

The prognostic significance of p21 and Her-2 gene expression and mutation/polymorphism in patients with gastric adenocarcinoma

Analyses of gene expression status and genetic polymorphisms are methods to identify novel histopathological prognostic factors. In patients with gastric cancer, some cell cycle regulators p53, p21, p27 and Her-2 oncogene have been proposed as prognostic factors. We aimed to investigate the expression and mutation/polymorphism of p21 and Her-2 and also relationship between that genes status and histopathological factors and prognosis in patients with gastric cancer. Forty-four patients with locally advanced gastric cancer were analyzed in this study from January 2000 to December 2008. Clinicopathological parameters, expression and mutation/polymorphism of p21 and Her-2 results were used to predict disease-free survival and overall survival. The positive expression of p21 and Her-2 was observed in 61.4 % (n = 27) and 9.1 % (n = 4) of all 44 tumors, respectively. p21 gene mutation and Her-2 gene polymorphism were detected in 20 % (n = 11) and 2.3 % (n = 1, II phenotype) of cases, respectively. The negative expression of p21 was correlated significantly with diffuse and undifferential type histologies, whole gastric involvement and positive vascular/neural invasion. The median survival rate of patients with negative expression was significantly poorer than that of patients with positive expression of p21 (17 vs. 27 months, p = 0.01, cox regression). p21 mutation was significantly higher in patients with diffuse (p = 0.03) and undifferential (p = 0.02) type histologies. There was no statistically significant association between histopathological parameters and Her-2 gene polymorphism/expression. The negative expression of p21 correlates with disease survival and may be a poor prognostic factor in patients with resected gastric cancer treated with adjuvant chemotherapy.

Synergistic role between p53 and JWA: prognostic and predictive biomarkers in gastric cancer

Expression of p53 appears to be correlated to prognosis in patients with malignancy, but its role in gastric carcinoma has remained controversial. Recently we reported that JWA, an ADP-ribosylation-like factor 6 interacting protein 5 (ARL6ip5), was both prognostic for overall survival and predictive for platinum-based treatment of gastric cancer. In this study, we aimed to investigate p53 expression as a prognostic and predictive marker in resectable gastric cancer, alone and in combination with JWA. Expression of p53 was examined in three large patient cohorts (total n = 1155) of gastric cancer. High expression of p53 was significantly correlated with unfavorable clinicopathologic parameters and decreased overall patient survival. Furthermore, patients with high p53 expression in tumors acquired remarkable survival benefit from adjuvant first-line platinum-based-chemotherapy. The synergy between p53 and JWA in predicting patient outcome was demonstrated, while no significantly elevated predictive value concerning chemotherapy was observed. Thus, p53 expression is a potent prognostic and predictive factor for resectable gastric cancer with adjuvant platinum-based chemotherapy. A combined effect of p53 with JWA as efficient prognostic indicators was found for the first time.

Human ribosomal protein S13 promotes gastric cancer growth through down-regulating p27(Kip1)

Our previous works revealed that human ribosomal protein S13 (RPS13) was up-regulated in multidrug-resistant gastric cancer cells and overexpression of RPS13 could protect gastric cancer cells from drug-induced apoptosis. The present study was designed to explore the role of RPS13 in tumorigenesis and development of gastric cancer. The expression of RPS13 in gastric cancer tissues and normal gastric mucosa was evaluated by immunohistochemical staining and Western blot analysis. It was found RPS13 was expressed at a higher level in gastric cancer tissues than that in normal gastric mucosa. RPS13 was then genetically overexpressed in gastric cancer cells or knocked down by RNA interference. It was demonstrated that up-regulation of RPS13 accelerated the growth, enhanced in vitro colony forming and soft agar cologenic ability and promoted in vivo tumour formation potential of gastric cancer cells. Meanwhile, down-regulation of RPS13 in gastric cancer cells resulted in complete opposite effects. Moreover, overexpression of RPS13 could promote G1 to S phase transition whereas knocking down of RPS13 led to G1 arrest of gastric cancer cells. It was further demonstrated that RPS13 down-regulated p27^kip1 expression and CDK2 kinase activity but did not change the expression of cyclin D, cyclin E, CDK2, CDK4 and p16^INK4A. Taken together, these data indicate that RPS13 could promote the growth and cell cycle progression of gastric cancer cells at least through inhibiting p27^kip1 expression.

Molecular analysis of gastric differentiated-type intramucosal and submucosal cancers

Identification of the molecular characteristics of intramucosal (IMCs) and submucosal cancers (SMCs) is essential to our understanding of early gastric carcinogenesis. However, little is known regarding the differences between the 2 lesions. One hundred and forty-eight patients with primary early gastric cancer [IMC, 106; SMC, 42] were characterized for expression of cell cycle-related proteins and loss of heterozygosity (LOH). We also examined microsatellite instability (MSI) and methylation status. For LOH and methylation studies, we used a panel of 17 microsatellite markers (3p, 4p, 5q, 9p. 13q, 17p, 18q and 22q) and promoter regions of 9 genes (MLH-1, RUNX3, p16, HPP1, RASSF2A, SFRP1, DKK-1, ZFP64 and SALL4) that are frequently altered or methylated in gastric cancers. Overexpression of p53 and cyclin D1 was observed in SMC. In addition, low expression of p27 was more frequent in SMC than in IMC. Frequencies of 4p, 9p, 13q and 22q were significantly higher in SMC than in IMC. The SALL4 gene was frequently methylated in SMC compared with IMC. However, other gene methylations were common in both IMC and SMC. The frequency of LOH-high status/methylation-low status was significantly higher in SMC than in IMC. However, LOH-low status/methylation-high status in SMC was more frequently found in IMC. Our data confirm that methylation of cancer-related genes plays a major role in the development of IMCs. Importantly, the results also show that gastric submucosal progression is characterized by the accumulation of specific genetic alterations. In addition, changes of cell cycle-related proteins are associated with cancer progression.

Prognostic significance of E-cadherin expression and peripheral blood micrometastasis in gastric carcinoma patients

BACKGROUND

The primary objective is to evaluate the prognostic value of E-cadherin (E-cad) expression and peripheral blood micrometastasis (PBMM) in gastric carcinoma. Secondary objective is to study the association between these 2 markers and the clinicopathological features of the patients.

MATERIALS AND METHODS

This study took place at Ain Shams University Hospitals. A total of 30 patients with histologically proven gastric adenocarcinoma after curative surgical resection were enrolled in this study. E-cad expression was assessed in tumor tissue samples. Before the start of adjuvant chemoradiotherapy, fresh blood samples were collected to detect PBMM as indicated by cytokeratin18 mRNA expression using real-time quantitative polymerase chain reaction (RQ-PCR).

RESULTS

Both abnormal E-cad expression and PBMM were significantly associated with lymph node metastasis, TNM stage, and lymphatic invasion. Moreover, PBMM was significantly associated with poor tissue differentiation and vascular invasion (P < .05). We found strong agreement between E-cad expression and presence of PBMM (P = .001). Both cases with altered E-cad expression and cases with positive PPMM showed shorter relapse-free survival (RFS) (P = .003 and <.001, respectively). Cox regression analysis showed that positive PBMM was independent predictor factor for relapse (hazard ratio [HR] = 6.14; 95% confidence interval [95% CI] = 1.06-35.63; P = .04). Cases with positive PBMM showed shorter overall survival (OS) (P = .001).

CONCLUSIONS

In conclusion, loss of normal E-cad expression in gastric cancer showed a close correlation with the presence of PBMM. PBMM was associated with poor RFS independent of other clinicopathological features. Additionally, detection of PBMM was a significant indicator of OS, and intensive chemotherapy seems to be indicated for these patients.

Analysis of cell cycle-related proteins in gastric intramucosal differentiated-type cancers based on mucin phenotypes: a novel hypothesis of early gastric carcinogenesis based on mucin phenotype

Background

Abnormalities of cell cycle regulators are common features in human cancers, and several of these factors are associated with the early development of gastric cancers. However, recent studies have shown that gastric cancer tumorigenesis was characterized by mucin expression. Thus, expression patterns of cell cycle-related proteins were investigated in the early phase of differentiated-type gastric cancers to ascertain any mechanistic relationships with mucin phenotypes.

Methods

Immunostaining for Cyclins D1, A, E, and p21, p27, p53 and β-catenin was used to examine impairments of the cell cycle in 190 gastric intramucosal differentiated-type cancers. Mucin phenotypes were determined by the expressions of MUC5AC, MUC6, MUC2 and CD10. A Ki-67 positive rate (PR) was also examined.

Results

Overexpressions of p53, cyclin D1 and cyclin A were significantly more frequent in a gastric phenotype than an intestinal phenotype. Cyclin A was overexpressed in a mixed phenotype compared with an intestinal phenotype, while p27 overexpression was more frequent in an intestinal phenotype than in a mixed phenotype. Reduction of p21 was a common feature of the gastric intramucosal differentiated-type cancers examined.

Conclusions

Our results suggest that the levels of some cell cycle regulators appear to be associated with mucin phenotypes of early gastric differentiated-type cancers.

Dysregulation of cellular signaling in gastric cancer

The pathogenesis of gastric cancer is complex and related to multiple factors. Dysregulation of intracellular signaling pathways represents a common pathogenic mechanism and may be amenable to drug targeting. Multiple well-established oncogenic pathways, such as those mediated by cell cycle regulators, nuclear factor-kappaB, cyclooxygenase-2 and epidermal growth factor receptor are implicated in gastric carcinogenesis. Emerging evidence also underscores the importance of signaling pathways involved in the developmental process, including transforming growth factor-beta/bone morphogenetic protein signaling, Wnt/beta-catenin signaling, Hedgehog signaling and Notch signaling. Understanding their biological significance will provide a rational basis for drug development. Their relative importance and cross-talk in gastric carcinogenesis, however, are still not completely understood and warrant further investigation.

p27KIP1 expression in gastric cancer: differential pathways in the histological subtypes associated with Helicobacter pylori infection

OBJECTIVE

Decreases in p27(KIP1) and C-MYC expression have been associated with Helicobacter pylori infection. Furthermore, C-MYC seems to be a transcriptional repressor of p27(KIP1). Therefore, in a series of gastric adenocarcinomas we studied the association of p27(KIP1) expression with H. pylori genotype (vacA, cagA, cagE and virB11) and the involvement of C-MYC in this process.

MATERIAL AND METHODS

Expression of p27(KIP1) and C-MYC was determined by immunohistochemistry in 84 gastric adenocarcinoma samples and H. pylori infection and genotype were determined by polymerase chain reaction.

RESULTS

Most p27(KIP1)-negative cases (94.0%) were H. pylori-positive and 44.8% were C-MYC-positive. In the diffuse gastric cancer subtype, p27-negative-C-MYC-positive was the most frequent combination (cluster II), and was associated with the more pathogenic H. pylori strains. Although an association with p27(KIP1) and H. pylori strain was found in the intestinal gastric cancer subtype, negativity for p27(KIP1) and C-MYC markers was the most frequent cluster, followed by cluster II, and both were present, independent of the H. pylori genotype.

CONCLUSIONS

Reduced expression of p27(KIP1) was closely linked to H. pylori infection, and was dependent on the more pathogenic strains. Moreover, intestinal and diffuse subtypes showed distinct carcinogenic pathways influenced by H. pylori strains. These data add insight to the differential influence and relevance of H. pylori genotype in gastric cancer development.

Clinicopathological significance of E-cadherin, β-catenin and p53 expression in gastric adenocarinoma

BACKGROUND

E-cadherin/catenin complexes exert a role in cell adhesion. β-catenin is a key player in Wnt signaling pathway in gastric cancer. P53 is a tumor suppressor gene which also regulates apoptosis. We assessed the expression of E-cadherin, β-catenin and p53 in gastric adenocarcinoma, and their correlations with clinicopathological features.

METHODS

Fifty six formalin-fixed, paraffin-embedded archival specimens of gastric adenocarcinoma were randomly included as cases. Adjacent tumor-free gastric mucosa of different premalignant stages was obtained from the cases. Immunohistochemical staining was performed to assess E-cadherin, β-catenin and p53 expression.

RESULTS

All chronic atrophic gastritis and intestinal metaplasia revealed normal membranous staining. Only one patient with dysplasia had abnormal expression of E-cadherin and β-Catenin. Abnormal E-cadherin, β-catenin and p53 expression was found in 50%, 48.2% and 76.8% of cancer specimens respectively. Abnormal expression of E-cadherin was significantly correlated with aberrant β-catenin expression. Abnormal E-cadherin and β-catenin expression were significantly correlated with depth of tumor invasion and advanced gastric cancer (p < 0.05), lower degree of differentiation and diffused tumor type (p < 0.001). Node metastasis was not influenced by abnormal expression of E-cadherin and β-catenin. P53 was not associated with clinicopathological variables.

CONCLUSIONS

Abnormal expression of the E-cadherin and β-catenin were associated with each other and influenced by histogenesis of gastric cancer and malignant behavior of tumor but not significant in premalignant lesions. They are more frequent in diffuse type and associated with advanced gastric cancer. P53 alterations are more frequent in the Iranian population compared with others.