Expression of mucins and cytokeratins in primary carcinomas of the digestive system

Cytokeratin 7/20 and mucin core protein expression in ulcerative colitis-associated colorectal neoplasms

Different histogenetic pathways have been suggested between ulcerative colitis (UC)-associated neoplasia and sporadic colorectal neoplasia. Little is known about the cytokeratin (CK) and mucin expression in UC-associated neoplasms. To clarify the characteristics of UC-associated colorectal carcinogenesis, we examined the immunohistochemical expression of CK7, CK20, MUC2, MUC5AC and MUC6 in 90 colorectal neoplasms, including 22 UC-associated adenocarcinomas (colitic cancer; CC), ten high-grade dysplasias (HGD) in UC, nine low-grade dysplasias (LGD) in UC, 24 sporadic tubular adenomas (TA) and 25 adenocarcinomas (AC). CK7 was positive in most of UC-associated neoplasms: 59% of CC cases, 80% of HGD and 89% of LGD, respectively, whereas, in non-UC associated neoplasia, 21% of TA and 12% of AC. The frequency of MUC6 expression in UC-associated neoplasia was 32% in CC, 30% in HGD and 44% in LGD, respectively, whereas, in non-UC associated neoplasia, 4.2% in TA and 0% in AC. MUC5AC expression in UC-associated neoplasia was detectable in 73% of CC, 90% of HGD and 89% of LGD, respectively; in non-UC associated neoplasia 67% in AC and 20% in TA. There were obvious differences in the expression of CK7 and MUC6 between UC-associated neoplasms and sporadic tumors. The incidence of MUC5AC expression in UC-associated neoplasms was also higher than sporadic tumors. These results suggest that gastric-type mucins play an important role in the initial step of CC-tumorigenesis, and CK7 and gastric-type mucins may be useful in the differential diagnosis between UC-associated neoplasms and sporadic ones.

Immunohistochemical expressions of cytokeratins, mucin core proteins, p53, and neuroendocrine cell markers in epithelial neoplasm of appendix

Epithelial neoplasms of appendix are infrequent, and their pathological features are not fully characterized. We collected 33 cases of appendiceal tumors and examined immunohistochemically the expression of cytokeratins (CK, CK7, and CK20), mucin core protein (MUC1, MUC2, MUC5AC, and MUC6), E-cadherin, chromogranin A, and p53 protein. Gene analysis of TP53 was also conducted on exons 5 to 8. Clinically, mucinous tumors were predominant in females. Immunohistochemically, all the tumors expressed CK20, whereas CK7 was positive in one third of the cases. Similarly, MUC2 was expressed in all the tumors, whereas MUC1 and MUC5AC were detected in about a half of the cases. Although chromogranin A-positive cells are generally sparse in normal appendix, they were more common in mucinous tumors than in nonmucinous tumors. Contrary to the previous data reported (Mod Pathol 2002;15:599-605), mucinous carcinoma exhibited a higher frequency of p53-positive cells (mean 29%) compared with mucinous adenoma (2.8%) (P < .001), whereas nonmucinous tumors showed high levels of p53-positive cells to similar extent (51%-67%) in both adenoma and carcinoma. The high expression of p53 protein coincided with the presence of mutations in multiple sites of TP53 gene in mucinous tumors. This is the first report that characterized the immunophenotypic profile of appendiceal epithelial neoplasms with an emphasis of a higher frequency of p53 positivity in mucinous carcinoma cases compared with mucinous adenoma in the appendix.

Detection of CK20 in peripheral blood of rectal cancer patients with fluorescence quantitative polymerase chain reaction and its significance

AIM: To analyze the relations of CK20 expression in the peripheral blood with the Dukes stages and histological types, and to discuss the value of fluorescence quantitative polymerase chain reaction (FQ-PCR) for predicting the metastases and prognosis of rectal cancer.

METHODS: The peripheral blood samples were collected from 47 patients with rectal cancer, 10 patients with benign intestinal diseases, and 10 healthy volunteers. Then FQ-PCR was performed to detect the expression of CK20 mRNA in the peripheral blood.

RESULTS: There was no positive expression of CK20 mRNA in the patients with benign intestinal diseases and the healthy volunteers, which was significantly different from that in the patients with rectal cancer (72.34%, 34/47) (χ² = 37.434, P < 0.01). The level of CK20 expression in the peripheral blood of the 47 patients with rectal cancer was positively correlated with the Dukes stages of rectal cancer (r = 0.680, P < 0.01).

CONCLUSION: The level of CK20 expression is positively related with tumor stages in the peripheral blood of the rectal cancer patients. CK20 detection by FQ-PCR is more sensitive than routine histological methods in predicting the metastases and prognosis of rectal cancer.

Expression of cytokeratins 7 and 20 in serrated adenoma and related diseases

The entity of serrated adenoma of the colorectum was first proposed in 1990, and it was characterized as epithelial neoplasia combining the architectural features of a hyperplastic polyp with the cytological features of an adenoma. Over the past few years, various clinicopathological studies on serrated adenoma have been reported, but its histogenesis remains unclear. Recently the existence of a "serrated neoplasia pathway" leading to malignancy, which is different from the so-called adenoma-carcinoma sequence, has been discussed. Yao et al. reported that hyperplastic polyps and serrated adenomas share a common cell lineage with gastric differentiation. To clarify the existence of the serrated neoplasia pathway, we performed immunohistochemical staining of cytokeratin 7 (CK7) and cytokeratin 20 (CK20), which are commonly used to determine the primary site of a metastatic lesion, and we examined the pattern of CK7/CK20 expression in various colorectal lesions including 44 serrated adenomas, 25 hyperplastic polyps, 20 traditional adenomas, and 48 carcinomas. An obvious difference existed in the pattern of CK7/CK20 expression between the serrated lesions (hyperplastic polyps and serrated adenomas) and others. The majority of serrated adenomas and hyperplastic polyps presented a CK7+/CK20+ pattern, whereas most conventional adenomas and adenocarcinomas expressed CK7-/CK20+. Adenocarcinoma developing in serrated adenoma also presented a CK7+/CK20+ pattern. There are several reports that CK7 is a possible marker of transient dedifferentiation in the gastric carcinogenesis process. Taken together with the present results, a distinct pathway of colorectal carcinogenesis must exist, which is different from the adenoma-carcinoma sequence. CK7 is a possible marker for the serrated neoplasia pathway of colorectal carcinogenesis.

Diagnostic challenge of secondary (metastatic) ovarian tumors simulating primary endometrioid and mucinous neoplasms

Secondary (metastatic) neoplasms to the ovary often cause diagnostic problems, especially those tumors that produce large, symptomatic ovarian tumors that masquerade clinically and pathologically as primary ovarian tumors of surface epithelial type. Most of these tumors arise from organs of the digestive system. Except for typical Krukenberg tumors, which usually originate in the stomach and generally are easily recognized, the most diagnostically problematic secondary ovarian tumors are those that originate in the large intestine, appendix, and pancreas. Metastases from these sites typically produce histologic patterns resembling primary ovarian endometrioid carcinoma or mucinous epithelial neoplasms of borderline and malignant types. This review focuses on the diagnostic challenge of distinguishing these secondary ovarian tumors from primary ovarian neoplasms. Studies on useful or potentially applicable immunohistochemical stains are also detailed.

Detection of CK20mRNA in peripheral blood of pancreatic cancer and its clinical significance

AIM: To detect the expression of CK20mRNA in peripheral blood of pancreatic cancer and evaluate its clinical significance.

METHODS: Expression of CK20mRNA in peripheral blood was detected by fluorogenic qualitative reverse transcription-polymerase chain reaction (RT-PCR) in 40 cases of pancreatic cancer at the night before operation, in 5 cases of benign pancreatic diseases, in 5 cases of healthy individuals. The relationships were investigated between CK20mRNA expression and the clinicopathological variables, and clinical follow-up outcome in those patients with pancreatic cancer having undergone radical resection.

RESULTS: Of the 40 patients with pancreatic cancer, 23 (57.5%) cases were positive for CK20mRNA expression. CK20mRNA expression was significantly correlated with lymphatic metastasis (P = 0.008), histopathological grading (P = 0.009), and pathological stage (P = 0.021); there was no significant correlation between CK20mRNA expression and age, gender, tumor diameter, and depth of invasion. The cumulative metastasis rates of patients with CK20mRNA expression were higher than those of patients with no CK20mRNA expression within 6 mo (34.7% vs 5.9%, P = 0.043) or 12 mo (73.9% vs 35.3%, P = 0.02) after operation. CK20mRNA expression in peripheral blood of pancreatic cancer indicated poorer prognosis. The survival rate of patients with CK20mRNA expression was lower than that of patients with negative CK20mRNA expression (Log-Rank = 13.31, P = 0.0003).

CONCLUSION: CK20mRNA is a sensitive and specific molecular marker for the detection of micrometastasis in peripheral blood of patients with pancreatic cancer. The CK20mRNA expression in peripheral blood is correlated with biological characteristic of pancreatic cancer. It can help to predict the prognosis of pancreatic cancer after operation, and to determine which patient will benefit from aggressive adjuvant therapies.

Phenotypic alterations of mucins and cytokeratins during gallbladder carcinogenesis

In order to evaluate the significance of altered expression of mucin and cytokeratin during gallbladder carcinogenesis, we characterized the expressional profiles of MUC1, MUC2, MUC5AC, MUC6, CK7 and CK20 in 33 normal mucosa, 31 adenomas, 55 dysplasias and 131 carcinomas of the gallbladder. In normal gallbladder mucosa, the expressions of MUC5AC and MUC6 were diffuse and MUC1 expression was absent. However, in adenomas, dysplasias and carcinomas, the expressions of MUC5AC and MUC6 tended to decrease, whereas MUC1 expression was elevated. MUC2 and CK20 were infrequently expressed in all of the gallbladder epithelia, but adenomas expressing MUC2 and/or CK20 were more frequently associated with carcinomas and showed a higher grade of atypia than those without these antigens. In carcinomas, MUC1 expression was related to invasive growth, lymph node metastasis and a non-papillotubular type, whereas MUC6 expression was related to non-invasive growth. CK7 was diffusely expressed in almost all lesions, but carcinomas with a loss of CK7 expression showed poor survival. In conclusion, normal gallbladder mucosa has a gastric phenotype, but during carcinogenesis and tumor progression, the gastric phenotype is gradually lost and the aberrant expression of MUC1 occurs. The intestinal phenotype is not common in the gallbladder.

Utility of CD10 and RCCma in the diagnosis of metastatic conventional renal-cell adenocarcinoma by fine-needle aspiration biopsy

The cytologic diagnosis of primary conventional renal-cell adenocarcinoma (cRCC) is usually straightforward; however, metastatic cRCC must be distinguished from a variety of neoplasms with clear-cell features. CD10, a cell membrane-associated neutral endopeptidase, and renal-cell carcinoma marker (RCCma), an antibody against human proximal tubular brush border antigen, have recently been shown to be useful in the diagnosis of cRCC. We compared CD10 and RCCma in cell block material from fine-needle aspiration biopsies (FNABs) to assess their utility in the diagnosis of metastatic cRCC, in cytologic specimens. Seven primary and sixteen metastatic cRCCs were immunostained with CD10 and RCCma. The immunoreactivity results were compared with those of a variety of neoplasms originating from other sites such as the liver, lungs, breast, and the gastrointestinal tract. The sensitivity and specificity of CD10 for cRCC were 100% and 59%, respectively. The sensitivity and specificity of RCCma for cRCC were 35% and 100%, respectively. We conclude that CD10 has limited value in confirming the diagnosis of cRCC because of its low specificity. RCCma, when positive, is highly specific for cRCC, but its low sensitivity hinders its diagnostic usefulness.

Alteration of Cytokeratin 7 and Cytokeratin 20 Expression Profile Is Uniquely Associated With Tumorigenesis of Primary Adenocarcinoma of the Small Intestine

Twenty-four cases of primary nonampullary small intestinal adenocarcinoma were immunohistochemically examined for the expression of cytokeratin (CK) 7 and CK20 and compared with 23 colorectal adenocarcinomas secondarily involving the small intestine by direct extension or metastasis. While normal small intestinal mucosa was diffusely positive for CK20 and completely negative for CK7 expression, all small intestinal adenocarcinomas (24 of 24) showed a variable degree of CK7 expression. Specifically, the CK7 staining pattern was diffuse in 13 cases (54%) and focal in the remaining cases. Sixteen small intestinal adenocarcinomas (67%) coexpressed CK7 and CK20, and 8 (33%) completely lost CK20 immunoreactivity when compared with adjacent non-neoplastic small intestinal mucosa. In the latter cases, the loss of CK20 immunoreactivity with a reciprocal emergence of CK7 expression was evident. This was in contrast to secondary colorectal adenocarcinomas where 22 cases (96%) expressed CK20, among which only 1 case showed focal CK7 expression. The remaining 1 case was negative for both CK7 and CK20. Interestingly, adenomatous epithelium associated with small intestinal adenocarcinomas identified in 18 cases also exhibited CK7 positivity with a sharp transition from CK7-negative normal-appearing epithelium. Taken together, these observations delineate an alteration of CK7 and CK20 expression profile that occurs early in small intestinal tumorigenesis. This unique pattern may be of diagnostic value in distinguishing primary small intestinal adenocarcinoma from secondary colorectal adenocarcinoma.

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Subcellular localization of the ABCG2 transporter in normal and malignant human gallbladder epithelium

Epithelium of the gallbladder and biliary tract is exposed to high concentrations of potentially harmful exogenous and endogenous compounds excreted into primary bile. As the ATP-dependent efflux pump ABCG2 can prevent cellular accumulation of anticancer drugs, estrogen sulfate, xenobiotics, porphyrins, and sterols, its expression in the biliary tract might mediate protection by hindering their penetration. We therefore investigated the expression and subcellular distribution of ABCG2 in normal and malignant human gallbladder. After demonstrating ABCG2 expression in gallbladder epithelium by RT-PCR and Western blotting, we analyzed the subcellular localization of ABCG2 by indirect immunofluorescence in gallbladder adenocarcinoma specimens, and compared it to that in cholelithiasis, and normal gallbladder samples (n = 54). In control, cholelithiasis, and well-differentiated tumor samples (grade 1, T1-3), ABCG2 is present at the luminal membrane of epithelial cells, which was proven by colocalization of apical-bound TRITC-labeled lectin (wheat germ agglutinin). In poorly differentiated gallbladder adenocarcinomas, intracellular ABCG2, in addition to luminal ABCG2 immunoreactivity, was found in 13/21 carcinoma samples (grade 2 and 3, T2-4, P < 0.01). In 3/11 of grade 3 tumors, ABCG2 was present in the cytoplasmatic compartment only (P < 0.01). In proliferating bile ducts of cholangiocarcinomas, ABCG2 showed an analogous staining pattern with presence in cytosolic compartments. However, the apical marker enzyme neutral endopeptidase remained on the membrane in all samples. To study whether phosphatidylinositol 3-kinase (PI3K) signaling might be necessary for ABCG2 membrane insertion, we treated freshly isolated human gallbladder epithelial cells with the PI3K inhibitor wortmannin. As assessed by indirect immunofluorescence, this maneuver redistributes ABCG2 to intracellular compartments. In conclusion, our data suggest a protective role for ABCG2 in well-differentiated gallbladder epithelial cells. Cytoplasmatic accumulation of ABCG2 in poorly differentiated carcinomas might coincide with malfunctioning of PI3K-signaling pathways during tumor progression.

MUC1 and MUC2 in pancreatic neoplasia

MUCs are glycoproteins with various roles in homeostasis and carcinogenesis. Among other actions, MUC1 may inhibit cell-cell and cell-stroma interactions and function as a signal transducer, participating in cancer progression. In contrast, MUC2 is normally found only in goblet cells, where it contributes to the protective barrier function of these cells. Recently, a tumour suppressor role has been demonstrated for MUC2, and both MUC1 and MUC2 appear to have important roles in pancreatic neoplasia. MUC1 appears to be a marker of aggressive phenotype and may facilitate the vascular spread of carcinoma cells. In contrast, MUC2 is rarely detectable in aggressive pancreatic tumours, but is commonly expressed in intraductal papillary mucinous neoplasms (IPMNs), which are rare, indolent tumours, in intestinal IPMNs, and in indolent colloid carcinomas. MUC2 appears to be not only a marker of this indolent pathway, but also partly responsible for its less aggressive nature. Thus, in pancreatic neoplasia, MUC1 and MUC2 have potential diagnostic and prognostic value as markers of aggressive and indolent phenotypes, respectively, and have potential as therapeutic targets.

Primary epithelial neoplasms and other epithelial lesions of the appendix (excluding carcinoid tumors)

Epithelial tumors of the appendix range from low-grade mucosal-based tumors which, when confined to the appendix, have an excellent prognosis but, once outside the appendix, have a fair prognosis and often a prolonged disease course, to high grade invasive carcinomas that are rapidly fatal. Low grade mucinous neoplasms may rupture and spread to the peritoneum as pseudomyxoma peritonei, and the nomenclature of these tumors has been the subject of considerable disagreement among pathologists; the designation "low grade appendiceal mucinous neoplasm" has recently been proposed for reasons discussed herein. Demonstrating rupture of these neoplasms may require particularly diligent gross and microscopic evaluation as the rupture site often heals over leaving only subtle evidence of its presence. Invasive adenocarcinomas are often mucinous and may also spread to the peritoneum. Against this backdrop, the clinical and pathologic features of low grade appendiceal mucinous neoplasms and mucinous adenocarcinomas, as well as other types such as typical colorectal type and signet-ring cell type, are reviewed. In addition, emerging entities, serrated polyps and serrated adenomas, whose significance is only beginning to be understood, are considered. Retention cysts, hyperplastic polyps, and diffuse mucosal hyperplasia, although not necessarily neoplastic, are reviewed here as they may enter into the differential diagnosis of appendiceal mucinous neoplasms.

Differentiation pathways in duodenal and ampullary carcinomas: a comparative study on mucin and trefoil peptide expression, including gastric and colon carcinomas

Duodenal carcinomas, such as ampullary tumors, may be a heterogeneous group of neoplasms that share differentiation features with gastric or colorectal carcinomas. Because of the cell- and tissue-specific expression patterns of mucins and trefoil peptides, these markers were used to investigate the differentiation status of duodenal and ampullary carcinomas in comparison with gastric and colorectal carcinomas. Adenocarcinomas (14 duodenal, 10 gastric, 11 ampullary and 10 colorectal) were examined immunohistochemically for the mucin gene products MUC1, MUC2, MUC5AC, MUC6 and the trefoil peptides TFF1 and TFF2. The tumors' expression profile for MUC5AC, MUC6 and TFF1 was used to distinguish between gastric- and intestinal-directed differentiation. The mucins that were most often expressed in the individual tumor types were MUC1 (duodenal and ampullary carcinomas), MUC2 (colorectal carcinomas) and MUC5AC (gastric carcinomas). Further classification focusing on the expression profile for MUC5AC, MUC6 and TFF1 revealed that 21% of the duodenal and 45% of the ampullary carcinomas demonstrated mainly gastric differentiation (positivity for all three markers or only two of them). The remaining duodenal and ampullary carcinomas showed nongastric, i.e., intestinal differentiation (all three markers negative or only one marker positive). The gastric differentiation pattern characterized 60% of gastric carcinomas. Colorectal carcinomas showed intestinal differentiation in 100% of cases. Duodenal carcinomas have a heterogeneous mucin expression pattern that is mainly related to either gastric differentiation or intestinal differentiation. This also holds for ampullary carcinomas. Among the markers used, MUC5AC, MUC6 and TFF1 are most useful for revealing differentiation pathways in duodenal and ampullary carcinoma.

Primary Mucinous (So-called Colloid) Carcinomas of the Lung

Herein we describe the clinicopathologic and immunohistochemical features of 13 primary mucinous (colloid) carcinomas (MCs) of the lung, an uncommon and controversial tumor. The patients, 7 males and 6 females, ranged in age from 50 to 79 years (mean, 64.5 years). All the tumors presented as a peripheral solitary nodule with gelatinous cut-surface and well circumscribed but lacking a complete fibrous wall. The size ranged from 1 to 5.5 cm. Microscopically, they consisted of neoplastic elements floating in large mucin pools and focally lining the alveolar spaces. Eleven cases were predominantly composed of tall, columnar goblet cells (goblet cell-type MC), while 2 consisted of signet-ring tumor cells (signet-ring cell-type MC). Five tumors were incidentally discovered by chest radiographs, while the others were symptomatic. All patients underwent complete surgical resection (six lobectomies and seven wedge resections). Postoperative chemotherapy was performed in 3 cases. Overall, the median follow-up was 26 months (mean 33 months; range 9-95 months). All patients with goblet cell-type MC were alive and well, while the 2 patients with signet-ring cell-type MC died of disease. Immunohistochemically, all the 11 goblet cell-type MCs were strongly stained with CDX-2 and MUC2, 8 reacted with TTF-1, 6 with cytokeratin 20 (CK20), 9 with cytokeratin 7 (CK7), and 2 with MUC-5AC. Conversely, the two signet-ring cell-type MCs were stained with TTF-1, CK7, and MUC5AC but were negative for CDX-2, MUC2, and CK20. Surfactant apoprotein-A (SP-A) was positive in four goblet cell-type and one signet-ring cell-type MC. When compared with 10 mucinous bronchioloalveolar carcinomas (m-BAC), the latter reacted with CK7, CK20, MUC5AC, TTF-1, SP-A, CDX-2, and MUC2 in 100%, 90%, 100%, 30%, 10%, 0%, and 0% of the cases, respectively. In summary, MC of the lung represents an entity with two distinct clinicopathologic and immunophenotypic variants: 1) the goblet cell-type, presenting a more indolent clinical behavior and frequently co-expressing markers of intestinal and pulmonary differentiation; and 2) the more aggressive signet-ring cell-type, which retains only markers of pulmonary origin. On morphologic and immunohistochemical grounds, MCs are easily distinguishable from m-BAC. Since goblet cell-type MC strongly stains with CDX2, MUC2, and CK20, differential diagnosis with metastatic colorectal carcinoma is very challenging and requires appropriate clinical correlation.