Immunohistochemical study of MUC5AC expression in human gastric carcinomas using a novel monoclonal antibody

Phenotypic classification of gastric signet ring cell carcinoma and its relationship with clinicopathologic parameters and prognosis

AIM: To distinguish subtypes of gastric signet ring cell (SRC) carcinoma by investigating the expression of gastric and intestinal phenotypic markers, and to study the significance of phenotypic classification in predicting tumor progression and outcome.

METHODS: Immunohistochemistry was performed in 66 cases of SRC carcinoma with MUC2, VILLIN, CDX2, Li-cadherin antibodies as intestinal phenotype markers and MUC5AC, HGM, MUC6 antibodies as gastric phenotype markers, and the relationship was analyzed between the phenotypic expression pattern and clinicopathologic parameters, as well as the 3-year survival rate.

RESULTS: Expression of intestinal phenotypic markers was positively associated with tumor size, wall invasion, vascular invasion, lymph node metastasis and tumor-node-metastasis (TNM) stage. Cases expressing one or more intestinal markers had a significant lower survival rate than cases expressing none of the intestinal markers.

CONCLUSION: The SRC carcinomas expressing intestinal phenotype markers exhibited a high pro-liferative potential, bad biological behaviors and poor prognosis. Examination of phenotype expression may be useful in distinguishing histological type and in predicting the prognosis of gastric SRC carcinoma.

Relationships between mucinous gastric carcinoma, MUC2 expression and survival

AIM: To investigate the expression of the four secreted gel-forming mucins (MUC2, MUC5AC, MUC5B and MUC6) in a series of gastric carcinomas, classified according Laurén’s, Mulligan’s, WHO and Goseki’s classifications, with special attention to all the different components (major and minor) present in tumors and to follow up clinical data.

METHODS: Expression of MUC2, MUC5AC, MUC5B and MUC6 was investigated using immunohistochemistry and in situ hybridization.

RESULTS: Expression of secreted gel-forming mucins in gastric carcinoma was particularly complex, each mucin being not restricted to any histopathological type even considering all components (major and minor) present in a given tumor. There was a worst survival in patients with a higher content of mucus (Goseki II or IV) and high positive MUC2 expression.

CONCLUSION: Complexity of mucin gene expression patterns in gastric cancer may reflect a precise state of differentiation at the cell level not recognized in used morphologic classification systems. High expression of MUC2 was nevertheless associated with mucinous subtype of the WHO classification and with group II of Goseki’s classification identified by the major component of a particular tumor. The quantity and quality of mucus were related to survival.

Differences in biological features of gastric dysplasia, indefinite dysplasia, reactive hyperplasia and discriminant analysis of these lesions

AIM: To investigate the differences in biological features of gastric dysplasia (Dys), indefinite dysplasia (IDys) and reactive hyperplasia (RH) by studying the biomarker alterations in cell proliferation, cell differentiation, cell cycle control and the expression of house-keeping genes, and further to search for markers which could be used in guiding the pathological diagnosis of three lesions.

METHODS: Expressions of MUC5AC, MUC6, adenomatous polyposis coli (APC), p53, Ki-67, proliferation cell nuclear antigen (PCNA) and EGFR were studied by immunohistochemistry with a standard Envision technique in formalin-fixed and paraffin-embedded specimens from 43 RH, 35 IDys, 35 Dys and 36 intestinal type gastric carcinomas (IGC). In addition, Bayes discriminant analysis was used to investigate the value of markers studied in differential diagnosis of RH, IDys, Dys and IGC.

RESULTS: The MUC5AC and MUC6 antigen expressions in RH, IDys, Dys and IGC decreased gradually (MUC5AC: 86.04%, 77.14%, 28.57%, 6.67%; MUC6: 65.15%, 54.29%, 20.00%, 25.00%, respectively). The expressions of the two markers had no significant difference between RH and IDys, but were all significantly higher than those of the other two lesions (MUC5AC: χ² = 27.607, 38.027 and 17.33, 26.092; MUC6: χ² = 16.54, 12.665 and 9.282, 6.737, P<0.01). There was no significant difference between RH and IDys, Dys and IGC in MUC6 expression. The APC gene expression in the four lesions had a similar decreasing tendency (RH 69.76%, IDys 68.57%, Dys 39.39%, IGC 22.86%), and it was significantly higher in the first two lesions than in the last two (χ² = 7.011, 16.995 and 14.737, 19.817, P<0.05). The p53 expression in RH, IDys, Dys and IGC was 6.98%, 20%, 57.14% and 50%, respectively. There was no significant difference between RH and IDys or Dys and IGC, but the p53 expression in RH and IDys was significantly lower than that in Dys and IGC (χ² = 7.011, 16.995 and 14.737, 19.817, P<0.01). The Ki-67 label index was significantly different among four lesions (RH: 0.298±8.92%, IDys: 0.358±9.25%, Dys: 0.498±9.03%, IGC: 0.620±10.8%, P<0.001). Positive immunostaining of PCNA was though observed in all specimens, significant differences were detected among four lesions (F = 95.318, P<0.01). In addition, we used Bayes discriminant analysis to investigate molecular pathological classification of the lesions, and obtained the best result with the combination of MUC5AC, Ki-67 and PCNA. The overall rate of correct classification was 67.4% (RH), 68.6% (IDys), 70.6% (Dys) and 84.8% (IGC), respectively.

CONCLUSION: Dys has neoplastic biological characteristics, while RH and IDys display hyperplastic characteristics. MUC5AC and proliferation-related biomarkers (Ki-67, PCNA) are more specific in distinguishing Dys from RH and IDys.

Co-expression of CDX2 and MUC2 in gastric carcinomas: Correlations with clinico-pathological parameters and prognosis

AIM: To evaluate the role of CDX2 homeobox protein as a predictor for cancer progression and prognosis as well as its correlation with MUC2 expression. CDX2 represents a transcription factor for various intestinal genes (including MUC2) and thus an important regulator of intestinal differentiation, which could previously be identified in gastric carcinomas and intestinal metaplasia.

METHODS: Formalin-fixed and paraffin-embedded tissues from 190 gastric carcinoma patients were stained with monoclonal antibodies recognizing CDX2 and MUC2, respectively. Immunoreactivity was evaluated semiquantitatively and statistical analyses including χ² tests, uni- and multi-variate survival analyses were performed.

RESULTS: CDX2 was mostly expressed in a nuclear or supranuclear pattern, whereas MUC2 showed an almost exclusive supranuclear reactivity. Both antigens were present in >80% of areas exhibiting intestinal metaplasia. An immunoreactivity in >5% of the tumor area was observed in 57% (CDX2) or in 21% (MUC2) of the carcinomas. The presence of both molecules did not correlate with WHO, Laurén and Goseki classification (with the exception of a significantly stronger MUC2 expression in mucinous tumors). CDX2 correlated with a lower pT and pN stage in the subgroups of intestinal and stage I cancers and was associated with MUC2 positivity. A prognostic impact of CDX2 or MUC2 was not observed.

CONCLUSION: CDX2 and MUC2 play an important role in the differentiation of normal, inflamed, and neoplastic gastric tissues. According to our results, loss of CDX2 may represent a marker of tumor progression in early gastric cancer and carcinomas with an intestinal phenotype.

Expression of mucins and E-cadherin in gastric carcinoma and their clinical significance

AIM: To investigate the expression of three types of mucin (MUC1, MUC2, MUC5AC) and E-cadherin in human gastric carcinomas and their clinical significance.

METHODS: Ninety-four gastric cancer specimens were classified according to WHO criteria and detected by immun-ohistochemical assay of expression of mucins and E-cadherin.

RESULTS: The positive expression rates of MUC1, MUC2, MUC5AC and E-cadherin were 82% (77/94), 84% (79/94), 40% (38/94) and 56% (53/94) respectively. MUC1 expression was significantly correlated with the types of cancer (the positive rates of MUC1 in well and moderately differentiated tubular adenocarcinoma, poorly differentiated adenocarcinoma, signet-ring cell carcinoma and mucinous carcinoma were 91%, 87%, 71%, 71%, respectively, P < 0.05), age of patients (the positive rates of it among the people who are younger than 40 years, between 40-60 years and over 60 year were 74%, 81%, 89%, P < 0.05), lymph nodes involvement (the positive rates in the non-interfered group and the interfered group were 78%, 85%, P < 0.05) and tumor size (the positive rates in the tumors with the size less than 3 cm, 3-6 cm and larger than 6 cm were 69%, 92%, 69%, P < 0.05); MUC2 expression was significantly associated with types of cancers and had the strongest expression in mucinous carcinomas (the positive rates of MUC2 in well and moderately differentiated tubular adenocarcinoma, poorly differentiated adenocarcinoma, signet-ring cell carcinoma and mucinous carcinoma were 94%, 70%, 81%, 100%, P < 0.05), but it had no obvious relation to age, gender, tumor location, lymph nodes involvement, depth of invasion and metastasis to extra-gastric organs (P > 0.05); MUC5AC expression was not related to any of the characteristics investigated except that it had relation to gender, whereas MUC5AC showed the tendency to higher expression in less invasive lesions and lower expression in advanced stage cancers (P > 0.05); No significant difference was found for E-cadherin expression. There were strong positive relationships between the expression of MUC1 and E-cadherin, MUC2 and E-cadherin, MUC1 and MUC2 (R = 0.33, R = 0.22, R = 0.32, respectively, P < 0.05). According to the COX proportional hazards model, older patients, involvement of lymph nodes, different types of gastric cancer and MUC2 expression were significantly associated with poorer outcome of gastric carcinoma patients (β = 0.08, β = 3.94, β = 1.33, β = 0.75, respectively, P < 0.05).

CONCLUSION: MUC1 and MUC2 are good markers of different types of gastric cancer. MUC2 is especially a good marker of mucinous carcinoma. MUC1, MUC2 may interfere with the function of E-cadherin in gastric carcinomas, and have synergic effect on progression of gastric cancers.