Abundant expression of AMACR in many distinct tumour types

AIMS: Alpha-methylacyl-CoA racemase (AMACR), a mitochondrial and peroxisomal enzyme, is a valuable tool to confirm the diagnosis of prostate cancer, especially if combined with basal cell markers. To extend this diagnostic utility to other neoplasias, we comprehensively surveyed AMACR expression in human tumours. METHODS: We performed immunohistochemical analyses on tissue microarrays of AMACR expression in over 125 different human tumour types and 80 normal tissues. RESULTS: Microarray analysis revealed that tumours with prominent AMACR expression included adenocarcinomas of the prostate (72%), hepatocellular carcinomas (77%), papillary renal cell carcinomas (70%), and colorectal adenocarcinomas (71%). AMACR expression was equally frequent in colorectal adenomas and carcinomas. No significant difference in AMACR expression between untreated and hormone-refractory prostate cancers was observed. In the thyroid, AMACR expression was found in 42% of the follicular carcinomas but in only 16% of follicular adenomas. However, a more detailed analysis on a thyroid tissue microarray did not confirm a significant difference of AMACR expression in follicular adenoma and carcinomas. CONCLUSION: Taken together, the results indicate that AMACR is expressed in a wide variety of adenocarcinomas, and its diagnostic utility is restricted to specific areas.     

Comprehensive analysis of HE4 expression in normal and malignant human tissues.

The HE4 (WFDC2) gene encodes a WAP-type four disulphide core domain-containing protein with a presumptive role in natural immunity. Multiple studies have consistently identified upregulation of HE4 gene expression in carcinomas of the ovary; however, the expression in normal and malignant adult tissues has not been examined in detail. Here, we examined the expression of the HE4 gene and protein in a large series of normal and malignant adult tissues by oligonucleotide microarray and tissue microarray, respectively. HE4 gene expression was highest in normal human trachea and salivary gland, and to a lesser extent, lung, prostate, pituitary gland, thyroid, and kidney. In a series of 175 human adult tumors, gene expression was highest in ovarian serous carcinomas. However, adenocarcinomas of the lung, and occasional breast, transitional cell and pancreatic carcinomas had moderate or high levels of HE4 expression. Using tissue microarrays and full tissue sections of normal and 448 neoplastic tissues, HE4 immunoreactivity was found in normal glandular epithelium of the female genital tract and breast, the epididymis and vas deferens, respiratory epithelium, distal renal tubules, colonic mucosa, and salivary glands, consistent with HE4 gene expression. In addition to consistent positivity in ovarian carcinoma, some pulmonary, endometrial, and breast adenocarcinomas, mesotheliomas, and less often, gastrointestinal, renal and transitional cell carcinomas were also positive. Knowledge of the expression patterns of HE4 in our survey is useful for application in histopathologic diagnosis, and should be taken into consideration in future studies that examine the role of HE4 as a serological tumor biomarker or as a target for gene-based therapy.     

Cell lineage specificity of newly raised monoclonal antibodies against gastric mucins in normal, metaplastic, and neoplastic human tissues and their application to pathology diagnosis

The specificity of monoclonal antibodies against gastric mucins (designated as HIK1083, PGM 36, and PGM 37) was studied immunohistochemically in normal, metaplastic, and neoplastic human tissues. These antibodies labeled class III mucin-producing cells identified by paradoxical concanavalin A staining in normal stomach, duodenum (Brunner gland), biliary tract, and main pancreatic duct; in mucinous metaplasia of pancreas and gallbladder; and in adenocarcinomas of stomach (90%), bile duct (80%), gallbladder (100%), pancreas (80%), lung (100% of goblet cell type adenocarcinomas), ovary (67% of mucinous carcinomas), and uterine cervix (100% of adenoma malignum tumors). Normal and neoplastic cells of esophagus, colon, salivary gland, kidney, endometrium, breast, prostate, and liver, as well as normal small intestine, lung, and uterine cervix, were all negative. The antibodies used should be valuable for the detection of class III mucin and class III mucin-producing cells in normal, metaplastic, and neoplastic tissues.     

Expression and distribution of insulin-like growth factor-1 receptor in human carcinomas

The insulin-like growth factor-1 receptor (IGF1-R) is a cellular receptor overexpressed in many tumor cell lines and in some human tumors that seems to play a critical role in transformation, tumorigenicity, and metastasis. To date, a comprehensive evaluation of tissue distribution of IGF1-R in human carcinomas from different anatomical sites has been lacking. Using stage-oriented human cancer tissue microarrays, we studied IGF1-R expression and distribution in a group of 152 human carcinomas from a variety of anatomical sites and from 63 normal tissues through immunohistochemistry. The tumors included carcinomas from breast (8), ovary (9), endometrium (7), esophagus (5), stomach (7), pancreas (7), liver (4), colon (10), kidney (14), bladder (17), prostate (11), head and neck (31), salivary glands (8), lung (13), and skin (1). Formalin-fixed, paraffin embedded tissues of each case were immuno-stained using the avidin-biotin peroxidase method and an anti-IGF1-R rabbit polyclonal antibody. High-membranous IGF1-R staining was observed in 7 of 8 (87.5%) breast carcinomas, in 9 of 9 (100%) ovarian carcinomas, in 7 of 7 (100%) endometrial carcinomas, in 5 of 7 (71.1%) gastric carcinomas, in 4 of 7 (57.1%) pancreatic carcinomas, in 9 of 10 (90%) colon adenocarcinomas, in 11 of 13 (84.6%) lung carcinomas, in 6 of 11 (54.5%) prostatic adenocarcinomas, and in 17 of 17 (100%) transitional cell carcinomas of the bladder. Only a minority of squamous cell carcinomas of the head and neck and esophagus (34), salivary gland tumors (5), and renal cell carcinomas (14) were IGF1-R positive. This study demonstrates the overexpression of IGF1-R across a wide variety of human carcinomas of glandular or transitional cell origin.     

Immunohistochemical expression of cytokeratins 7 and 20 in malignant salivary gland tumors.

On the basis of the heterogeneity of cytokeratins 7 and 20 expression in malignant epithelial tumors, the cytokeratin 7/20 immunophenotype has served as a useful diagnostic tool for discrimination of primary and/or metastatic carcinomas of unknown origin. However, the expression pattern of these cytokeratins in malignant salivary gland tumors has not been thoroughly studied. Our study material was composed of 84 malignant tumors of primary major or minor salivary gland origin. Nine histologic types of carcinoma were represented, including mucoepidermoid (26 cases), adenoid cystic (25), polymorphous low grade (11), salivary duct (8), acinic cell (4), ex mixed tumor (3), not otherwise specified (3), clear cell (2), and basal cell (2). In all, 13 cases of primary skin or mucosal squamous cell carcinoma with secondary salivary gland involvement were also examined. Immunoreactivity for cytokeratin 7 was evident in all malignant salivary gland tumors; the staining pattern was diffuse and strong in 62 cases, and focal and strong in 22 cases. In contrast, 78 cases were negative for cytokeratin 20, whereas only six cases (two mucoepidermoid, one adenoid cystic, and three salivary duct) displayed focal weak positivity. Overall, 92.9% of malignant salivary gland tumors were characterized by a cytokeratin 7 positive/20 negative immunoprofile, the remaining 7.1% of cases being positive for both cytokeratins. The latter phenotype was more common in salivary duct carcinomas (P< or =0.05). On the other hand, most squamous cell carcinomas (69%) were negative for both cytokeratins, while the remaining cases (31%) were negative for cytokeratin 20 and focally weakly positive for cytokeratin 7. We suggest that assessment of cytokeratin 7/20 immunoprofile may facilitate the differential diagnosis of (a) primary malignant salivary gland tumors from metastatic tumors, (b) metastatic salivary gland tumors, (c) primary salivary gland tumors, especially mucoepidermoid carcinomas, from squamous cell carcinomas, and (d) salivary duct carcinomas from other malignant salivary gland tumors.     

Expression of androgen,estrogen, and progesterone receptors in salivary gland tumors. Frequent expression of androgen receptor in a subset of malignant salivary gland tumors

The expression of sex hormone receptors in some tumors suggests a role for these receptors in tumor pathogenesis and therapy. Previous studies of the expression of estrogen and progesterone receptors in salivary gland tumors have reported conflicting results. We evaluated the immunohistochemical expression of androgen, estrogen, and progesterone receptors (AR, ER, and PR) in a series of 78 formalin-fixed, paraffin-embedded salivary gland tumors. Immunoreactivity for AR was seen in 14 of 14 carcinoma ex pleomorphic adenomas, 6 of 6 salivary duct carcinomas, and 2 of 2 basal cell adenocarcinomas but in only 2 of 10 acinic cell carcinomas, mucoepidermoid carcinomas, and adenoid cystic carcinomas each. AR expression was distributed evenly between the sexes. ER and PR were expressed in only a few cases of salivary gland tumors. All 26 benign salivary gland tumors were negative for AR, ER, and PR. The uniform expression of AR exclusively in a subset of malignant salivary gland tumors suggests a possible role for AR in the histogenesis and possibly in the clinical management of these malignant salivary gland tumors.     

Alpha-methyl CoA racemase expression in renal cell carcinomas

Alpha-methyl CoA racemase (AMACR), a new molecular marker for prostate cancer, has been recently reported to be one of the most highly expressed genes in papillary renal cell carcinomas (RCCs). We tested the diagnostic usefulness of AMACR antibody in a series of 110 renal tumors: 53 papillary RCCs (33 type 1, 20 type 2); 25 conventional RCCs; 6 chromophobe RCCs; 9 oncocytomas; 5 mucinous tubular and spindle tumors; 2 urothelial carcinomas; 7 angiomyolipomas; and 2 Bellini carcinomas. Immunohistochemical staining was performed on formalin-fixed, paraffin-embedded tissue sections, with a primary prediluted rabbit monoclonal anti-AMACR antibody. Both type 1 and type 2 papillary RCCs exhibited cytoplasmic immunoreactivity for AMACR, with diffuse strong granular staining in 96.4% (53/55) of tumors, without correlation with type or nuclear grade. The 5 mucinous, tubular, and spindle cell carcinomas strongly expressed AMACR, and only 5 of 25 clear cell RCCs and 1 of 9 oncocytomas were focally reactive. The remaining 6 chromophobe RCCs, 5 urothelial carcinomas, and Bellini duct carcinomas showed no immunoreactivity for AMACR. Because high expression of AMACR is found in papillary RCCs (type 1 and 2) and in mucinous, tubular, and spindle cell carcinomas of the kidney, immunostaining for AMACR should be used in conjunction with other markers when histological typing of a renal tumor is difficult.     

AMACR is highly expressed in gastric adenomas and intestinal-type carcinomas

Alpha-methylacyl-CoA racemase (AMACR) is a novel tumor biomarker expressed in a number of neoplasms, including colorectal and prostatic adenocarcinomas. However, AMACR expression has not been investigated in preneoplastic and neoplastic lesions of the stomach. Using immunohistochemistry we studied the expression of AMACR in normal gastric mucosa (n=32), intestinal metaplasia (n=26), adenomas (n=29) and adenocarcinomas (n=132) of the stomach from 135 patients. Synchronous adenocarcinomas arising in the background of adenomas were observed in 26 cases. AMACR immunoreactivity was not observed in all normal gastric mucosa. Tissue from intestinal metaplasia, adenomas, and adenocarcinomas was positive in 7.7% (2/26), 79.3% (23/29), and 62.9% (83/132) of cases, respectively. The difference in AMACR expression between adenomas or adenocarcinomas and non-neoplastic mucosa was statistically significant (p=0.0001). Moreover, intestinal-type carcinomas showed significantly higher expression of AMACR (69.8%) compared to diffuse-type carcinomas (47.2%) (p=0.02). Our results indicate that as well as being an additional diagnostic tool, altered AMACR expression in gastric adenomas and intestinal-type carcinomas suggests that AMACR may be involved early in the development of intestinal-type gastric carcinomas.     

c-fos oncogene underexpression in salivary gland tumors as measured by in situ hybridization.

Tissue from 35 salivary gland tumors and 14 normal salivary glands was analyzed by in situ hybridization and computer-assisted morphometry for the expression of the c-fos oncogene. The normal salivary gland tissues were found to express c-fos focally, mainly in the acinar secretory cells. The majority of the cells in the normal tissues showed a high level of expression (47.74 +/- 5.31% of cells had 46 to 60 grains per cell and another 45.79 +/- 2.18% showed > 60 grains per cell). All the tumors examined exhibited a relatively low, uniform distribution of c-fos expression. For example, in the poorly differentiated adenocarcinomas, 96.83 +/- 04% of the cells were found to have < 15 grains per cell. A general linear model for multivariate analysis showed a significant difference between the various tumor types and the normal salivary gland tissues (P = 0.0001). These data support the hypothesis that salivary gland tumors belong to a group of epithelial neoplasias in which the loss of cellular differentiation is linked with underexpression of the c-fos oncogene.     

Gross cystic disease fluid protein-15 in salivary gland tumors

Gross cystic disease fluid protein-15 (GCDFP-15) is a 15-kd glycoprotein that is expressed by normal apocrine epithelia and in a majority of breast carcinomas. However, recent studies have demonstrated that this substance is also present in tumors of the salivary glands, sweat glands, and prostate gland. To determine whether the expression of CGDFP-15 might aid in the differential diagnosis of salivary gland lesions, the anti-GCDFP-15 monoclonal antibody D6 was applied to paraffin sections of 133 such neoplasms. Benign tumors (76% reactive) were more often labeled than malignant lesions (28% reactive) by this antibody; overall, 53 (41%) of 133 cases were positive for GCDFP-15. Notably, the tubuloglandular components in 17 (81%) of 21 pleomorphic adenomas were reactive, but no example of either adenoid cystic carcinoma or polymorphous low-grade adenocarcinoma were labeled. In contrast, 24% of adenocarcinomas stained with this antibody. The apparent expression of GCDFP-15 by a spectrum of salivary gland tumors supports their biologic relationship to lesions of the cutaneous apocrine glands and breast. Furthermore, the demonstration of this determinant may be of use in suggesting the salivary gland nature of poorly differentiated carcinomas of the head and neck, and it may facilitate the separation of pleomorphic adenoma from histologically similar malignant neoplasms in the salivary glands themselves.     

Distribution of p63, cytokeratins 5/6 and cytokeratin 14 in 51 normal and 400 neoplastic human tissue samples using TARP-4 multi-tumor tissue microarray

p63, cytokeratin (CK) 5/6 and CK 14 have been employed in diagnostic pathology as markers of basal, squamous and myoepithelial differentiation in several types of human neoplasms; however, there is scant data on the concurrent expression of these markers in large series of human neoplasms. We analyzed the distribution of these three immunohistochemical markers in 51 normal human tissue samples, 350 carcinomas, 25 malignant melanomas (MMs), and 25 glioblastomas using three serial sections of tissue array research program (TARP)-4 multi-tumor tissue microarray. Also, we performed double immunostainings to characterize the differential distribution of p63/CK 5/6 and p63/CK 14 in normal breast, salivary gland and skin. p63, CK 5/6 and CK 14 were expressed in basal cells of the prostate and respiratory epithelia and in breast and bronchial myoepithelial cells. p63 was also expressed in cytotrophoblast cells of human placenta and in scattered cells of lymph node germinal center. CK 5/6 and CK 14 also stained the cytoplasm of basal cells of esophageal stratified squamous epithelium and transitional epithelial cells of the bladder. No mesenchymal, neural, endothelial, smooth muscle or adipose cells were stained by any of the markers. p63, CK 5/6, and CK 14 were respectively expressed in 92.6%, 75.0%, and 52.9% of the squamous cell carcinomas of the lung, 10.2%, 20.0%, and 7.4% of the ductal carcinomas of the breast, 12.9%, 34.4%, and 11.8% of the serous and 25.0%, 0%, and 0% of the endometrioid carcinomas of the ovary. Lung, prostate and colonic adenocarcinomas, as well as MMs and glioblastomas were only rarely decorated by one of the markers. Only matched samples of 16 squamous cell carcinomas and two ductal carcinomas of the breast co-expressed these three markers. In double immunostainings, p63-CK 5/6, as well as p63-CK 14 were co-expressed by basal/myoepithelial cells of the salivary glands and basal cells of the epidermis. Our results demonstrate that p63, CK 5/6 and CK 14 may be used together in immunohistochemical panels to characterize squamous differentiation in poorly differentiated carcinomas or carcinomas of unknown origin.     

Conserved antigen expression in epithelial tumors recognized by monoclonal antibody 4A9 generated against canine mammary carcinoma cells

Hybridoma-derived murine monoclonal antibodies (MoAbs) were generated by fusing P3X63-Ag8.653 myeloma cells with splenic cells from BALB/c mouse which had been immunized with viable canine mammary adenocarcinoma cells, CMT-2. Fifteen MoAbs were shown to react with immunizing cells in indirect immunofluorescence (IFA) and enzyme-linked immunosorbent (ELISA) assays. The reactivity of one IgM MoAb, designated 4A9, was evaluated. The antigen recognized by 4A9 on CMT-2 cells appeared to be localized both in cell membrane and cytoplasm against fixed and unfixed preparations by IFA. The 4A9 MoAb was found to bind with four of five canine mammary carcinoma cell lines while no binding was detected with normal fibroblastic cell lines. In vivo tissue distribution of 4A9 antigen was evaluated by indirect immunoperoxidase (IP) assay against formalin-fixed, paraffin-embedded sections of normal and neoplastic tissues. 4A9 MoAb reacted strongly to moderately with 75% of mammary carcinomas, moderately to weakly with 57% of benign mammary tumors, and strongly with squamous cell and perianal gland carcinomas (100%), interstitial cell tumors (100%), transitional cell carcinomas (43%), lung adenocarcinomas (40%), colon carcinomas (33%), and pancreatic adenocarcinomas (20%). Moderate to weak staining was detected with granulosa cell tumors (25%) and apocrine gland adenocarcinomas (50%). Strong reactivity with perianal gland carcinomas contrasted to no reactivity with perianal gland adenomas. No immunostaining was detected with a large variety and number of normal adult and fetal tissues tested; negligible and very restricted staining was observed in a few adult and fetal tissues. Normal mammary gland was negative. Since the antigen is expressed on the cell surface and in the cytoplasm of most mammary carcinoma cells and a variety of other epithelial tumor cells, the 4A9 antibody may have potential application in diagnosis and management of canine mammary cancer and a variety of other epithelial tumors.     

The myoepithelial immunophenotype in 135 benign and malignant salivary gland tumors other than pleomorphic adenoma.

BACKGROUND: We have previously studied the immunoreactivity of 3 novel smooth muscle-specific proteins, alpha-smooth muscle actin, smooth muscle myosin heavy chains, and calponin, to assess myoepithelial differentiation in pleomorphic adenomas. OBJECTIVE: To further expand our knowledge of myoepithelial differentiation in other benign and malignant salivary gland tumors. DESIGN: Formalin-fixed paraffin sections of 135 salivary gland tumors with associated normal glands were stained with monoclonal antibodies using the avidin-biotin complex immunoperoxidase method and enzymatic and microwave heat-induced epitope retrieval. RESULTS: In adenoid cystic carcinomas and epithelial-myoepithelial carcinomas, all 3 markers exclusively highlighted the myoepithelial cell components and the epithelial cells were entirely negative. No immunostaining was detected in canalicular adenomas, oncocytomas, Warthin tumors, acinic cell carcinomas, mucoepidermoid carcinomas, squamous cell carcinomas, and polymorphous low-grade adenocarcinomas. Salivary duct carcinomas and adenocarcinomas, not otherwise specified had a distinctive pattern of uniform periductal staining of reactive myofibroblastic cells, and in salivary duct carcinomas some ducts retained a peripheral immunoreactive myoepithelial cell layer. CONCLUSION: Immunoreactivity for these 3 smooth muscle-specific proteins confirms the known neoplastic myoepithelial component of adenoid cystic carcinomas and epithelial-myoepithelial carcinomas. The consistently positive staining pattern in adenoid cystic carcinomas may be diagnostically useful in discriminating histologically similar but consistently negative polymorphous low-grade adenocarcinomas. Periductal linear staining in adenocarcinoma, not otherwise specified and salivary duct carcinomas is distinctive and appears to represent a tight cuff of myofibroblasts associated with the infiltrating glands.     

Expression of vascular endothelial growth factor in human gastric carcinomas

Vascular endothelial growth factor (VEGF), also known as vascular permeability factor, is a secreted protein which may play a pivotal role in tumor-associated microvascular angiogenesis and hyperpermeability. The expression of mRNA for VEGF was examined in eight gastric carcinoma cell lines and 30 gastric carcinoma tissues as well as corresponding normal mucosa. All the cell lines expressed VEGF mRNA at various levels that correlated well with the amounts of VEGF secreted into the condition medium. The expression of VEGF mRNA by TMK-1 cells was increased by the treatment of epidermal growth factor (EGF) or interleukin-1α (IL-1α), whereas it was decreased by the treatment of interferon-β (IFN-β). In gastric carcinoma tissues, the level of VEGF mRNA in primary tumors was higher than that in the corresponding normal mucosas in six (46%) of 13 well-differentiated adenocarcinomas and in two (12%) of 17 poorly differentiated adenocarcinomas, respectively. Vessel counts in well-differentiated adenocarcinomas had a tendency to be higher than those in poorly differentiated adenocarcinomas. In well-differentiated adenocarcinomas, the levels of VEGF mRNA expression tended to be higher in carcinomas of advanced stage than in early stage carcinomas. Both in situ mRNA hybridization and immunohistochemistry demonstrated the presence of VEGF expression within the tumor cells. These results suggest that VEGF may confer angiogenesis and progression of human gastric carcinomas, especially of the well-differentiated type.     

Expression of native and deglycosylated colon cancer mucin antigens in normal and malignant epithelial tissues

Immunohistochemical techniques were used to determine the distribution and cellular location of the mature and precursor forms of a colonic-type mucin in normal and malignant epithelial tissues. The antisera used in this study were prepared against native human colon cancer mucin (LS), partially deglycosylated mucin (HFA or GalNAc-apomucin), and fully deglycosylated mucin (HFB or apomucin). These antisera reacted with most mucin-producing cells of the normal gastrointestinal tract, salivary ductular cells, bronchial epithelial cells, some bronchial mucous glands, and squamous epithelial cells of the esophagus. Breast, endometrium, ovary, prostate, liver, and thyroid were nonreactive. In most normal organs, HFB reactivity was present in the supranuclear and perinuclear cytoplasm and LS and HFA were located primarily in goblet cell vacuoles, apical cytoplasm, and luminal secretions. These findings are consistent with the expected subcellular locations of apomucin and more "mature" mucins. LS, HFA, and HFB were frequently expressed in adenocarcinomas of the colon, stomach, pancreas, and lung. Lymphoma, sarcoma, and melanoma specimens were nonreactive. Alterations in the expression of these mucin antigens in malignant tissues included loss of subcellular compartmentalization, increased intensity of staining, and disappearance of staining. In addition, de novo expression of HFB was observed in one of five breast carcinomas and three of five ovarian mucinous cystadenocarcinomas. These data demonstrate that LS, HFA, and HFB are useful for studying the organ specificities and biosynthetic pathways of one type of mucin in normal and malignant tissues.     

Molecular characterization of salivary gland malignancy using the Smgb-Tag transgenic mouse model

The molecular mechanisms underlying salivary gland tumorigenesis remain unclear. In order to identify genetic changes that occur during the development of invasive adenocarcinoma from normal salivary gland, we used the Smgb-Tag transgenic mouse model. This transgene induces the progressive development of dysplasia to invasive adenocarcinoma in the submandibular salivary gland. Gene expression patterns from 20 submandibular glands (two normal, nine dysplasia and nine adenocarcinoma samples) were assessed using a mouse 15 K cDNA array. Unsupervised hierarchical clustering was used to group gene expression based on 157 differentially expressed genes distinguishing between dysplasias and adenocarcinomas. Further analysis identified 25 significantly overexpressed and 28 underexpressed cDNA sequences in adenocarcinoma as compared to dysplasia. Differential expression of five genes (Lcn2, Ptn, Cd24a, Mapk6 and Rnps1) was validated by quantitative real-time RT-PCR in a total of 48 mouse salivary gland tissues (seven histologically normal, 13 dysplasias and 28 adenocarcinomas), including the 20 samples analyzed by cDNA arrays. Immunohistochemical analysis was used to validate the expression of Ptn and Cd24a at the protein level in a subset of 16 mouse salivary glands (four normal, five dysplasia and seven adenocarcinoma samples), as well as in 23 human submandibular gland tumors (16 pleomorphic adenomas, three adenoid cystic carcinomas, one acinic cell carcinoma, one adenocarcinoma NOS, one myoepithelial and one mucoepidermoid carcinoma). We thus demonstrated that the Smgb-Tag transgenic mouse model is a useful tool for the identification of genes that are deregulated in salivary gland adenocarcinomas. Our data suggest that Ptn and Cd24a may be genetic markers associated with salivary gland tumorigenesis and/or progression.     

Differential expression of epithelial cell adhesion molecule in salivary gland neoplasms

Epithelial cell adhesion molecule (EpCAM) is the epithelial-specific molecule expressed on various epithelial cell types. The function of EpCAM involves cellular adhesion, proliferation, and signaling in both normal tissues and cancers. The purposes of this study were to investigate the EpCAM expression in salivary gland neoplasms and examine its relationship with pathologic characteristics. Forty-two cases of salivary gland neoplasms, including 20 mucoepidermoid carcinomas (MECs), 11 adenoid cystic carcinomas (ACCs), 9 pleomorphic adenomas (PAs), and 2 polymorphous low-grade adenocarcinomas (PLGAs) were enrolled. Epithelial cell adhesion molecule expression was analyzed immunohistochemically using MOC-31 and BerEP4 antibodies. Results showed that the majority of MECs and all PLGAs showed EpCAM expression in more than 50% of neoplastic cells, whereas most PAs and ACCs did not express this protein. In MECs, most EpCAM-positive neoplastic cells were clear cells, glandular epithelial cells, and intermediate cells, whereas squamous cells and mucous cells were largely negative. The expression was limited to ductal epithelium in EpCAM-positive PAs and ACCs. The decreased EpCAM expression in MECs was significantly associated with microscopically diminished cystic components, the presence of small nest invasion at invasive front, cellular anaplasia, vascular invasion, and high pathologic grade. These data suggested that EpCAM showed different expression pattern among salivary gland neoplasms and in different grades of MECs.