Histochemical observations on mucins in human ovarian neoplasms

Applications and continued evolution of glycan imaging mass spectrometry

Glycosylation is an important posttranslational modifier of proteins and lipid conjugates critical for the stability and function of these macromolecules. Particularly important are N-linked glycans attached to asparagine residues in proteins. N-glycans have well-defined roles in protein folding, cellular trafficking and signal transduction, and alterations to them are implicated in a variety of diseases. However, the non-template driven biosynthesis of these N-glycans leads to significant structural diversity, making it challenging to identify the most biologically and clinically relevant species using conventional analyses. Advances in mass spectrometry instrumentation and data acquisition, as well as in enzymatic and chemical sample preparation strategies, have positioned mass spectrometry approaches as powerful analytical tools for the characterization of glycosylation in health and disease. Imaging mass spectrometry expands upon these strategies by capturing the spatial component of a glycan's distribution in-situ, lending additional insight into the organization and function of these molecules. Herein we review the ongoing evolution of glycan imaging mass spectrometry beginning with widely adopted tissue imaging approaches and expanding to other matrices and sample types with potential research and clinical implications. Adaptations of these techniques, along with their applications to various states of disease, are discussed. Collectively, glycan imaging mass spectrometry analyses broaden our understanding of the biological and clinical relevance of N-glycosylation to human disease.

Comparative glycoproteomics study on the surface of SKOV3 versus IOSE80 cell lines

Objective: Site- and structure-specific quantitative N-glycoproteomics study of differential cell-surface N-glycosylation of ovarian cancer SKOV3 cells with the non-cancerous ovarian epithelial IOSE80 cells as the control.

Methods: C18-RPLC-MS/MS (HCD with stepped normalized collision energies) was used to analyze the 1: 1 mixture of labeled intact N-glycopeptides from SKOV3 and IOSE80 cells, and the site- and structure-specific intact N-glycopeptide search engine GPSeeker was used to conduct qualitative and quantitative search on the obtained raw datasets.

Results: With the control of the spectrum-level false discovery rate ≤1%, 13,822 glycopeptide spectral matches coming from 2,918 N-glycoproteins with comprehensive N-glycosite and N-glycan structure information were identified; 3,733 N-glycosites and 3,754 N-glycan sequence structures were confirmed by site-determining and structure-diagnostic fragment ions, respectively. With the control of no less than two observations among the three technical replicates, fold change ≥1.5, and p-value ≤ 0.05, 746 DEPGs in SKOV3 cells relative to IOSE80 cells were quantified, where 421 were upregulated and 325 downregulated.

Conclusion: Differential cell-surface N-glycosylation of ovarian cancer SKOV3 cells were quantitatively analyzed by isotopic labeling and site- and structure-specific N-glycoproteomics. This discovery study provides putative N-glycoprotein biomarker candidates for future validation study using multiple reaction monitoring and biochemical methods.

Functional impact of tumor-specific N-linked glycan changes in breast and ovarian cancers

Changes in glycosylation have been implicated in various human diseases, including cancer. Research over the past few decades has produced significant findings that illustrate the importance of cancer-specific alterations in glycosylation in the regulation of tumor formation and metastasis. The identification of glycan-based biomarkers and strategies targeting specific glycan epitopes on the tumor cell surface has become one of the widely pursued research areas. In this chapter, we will summarize and provide perspective on available knowledge about the functional roles that glycan structures play in the development and progression of the gynecological cancers, breast and ovarian, with a specific focus on N-linked glycans. A better understanding of the functional roles for glycans in cancer will drive future innovations for diagnostics and therapeutics.

Transitional cell carcinoma pattern in primary carcinoma of the fallopian tube

BACKGROUND

A broad papillary proliferation resembling that in transitional cell carcinoma (TCC) of the urinary bladder was seen in 12 of 21 primary carcinomas of the Fallopian tube (PCFT).

METHODS

According to their predominant histologic pattern (more than 50%), PCFT were classified into 9 TCC-predominant and 12 non-TCC-predominant tumors. The two groups were compared by clinicopathologic, histochemical, and immunohistochemical means.

RESULTS

TCC-predominant tumors were grossly solid and microscopically demonstrated more frequent tumor necrosis and spindled tumor cells than non-TCC-predominant tumors. Mucin histochemistry revealed a correlation between TCC-predominant tumor and sulfomucin-predominant secretion and between non-TCC-predominant tumor and sialomucin-predominant secretion. Immunohistochemical studies for cytokeratins, vimentin, epithelial membrane antigen (EMA), Leu-M1, carcinoembryonic antigen (CEA), and CA 125 were not useful for discrimination between the two groups. Both groups showed similar features in patient age, clinical stage, cytology of ascites or peritoneal washing, and serum CA 125 level. Despite the similarity in treatment (surgery and postoperative chemotherapy) between the two groups, TCC-predominant tumors tended to relapse later (mean, 31.2 months after diagnosis) than non-TCC-predominant tumors (mean, 14.4 months after diagnosis), resulting in a significant difference in the 2-year disease-free survival rate.

CONCLUSIONS

TCC pattern and non-TCC pattern are considered to be worthy of distinction in PCFT.

Lectin binding to serous ovarian tumours

Sections of normal ovarian surface epithelium, benign serous cystadenomas, borderline serous cystadenomas and serous cyst-adenocarcinomas were stained with a pattern of lectins (Con A, WGA, SBA, DBA, UEA I, PNA and RCA I) to determine the different glycoproteins and their cellular changes. The epithelial cells stained with Con A, WGA, UEA I and RCA, although the intensity of the staining was generally higher in the malignant tumours. PNA stained only the malignant cells of the cystadenocarcinoma and DBA only the benign epithelial cells. These findings show that ovarian epithelial cells contain different glycoconjugates and that malignant transformation is accompanied by changes in the composition of these glycoconjugates.

Mucosubstances in classification of serous and mucinous ovarian tumors: a morphometrical study

108 serous and 106 mucinous ovarian cystadenomas of varying malignancy were studied with the saliva-periodic acid-Schiff (SPAS) reaction and with the Alcian blue (AB) pH 2.7 method, which stain neutral and acid mucosubstances, respectively. Positively stained mucin was quantitated morphometrically and the measured parameters were tested by discriminant analysis. As expected, the mucinous tumors were more positive for mucin than the serous ones. Also the borderline tumors contained more mucin than their benign or malignant counterparts. The best discriminating capacity for mucin was obtained in serous tumors with the AB stain and in mucinous tumors with the SPAS reaction. The ratio of neutral to acid mucosubstances decreased in mucinous cystadenomas with increasing malignancy.

Periodic acid-Schiff stain as a prognostic indicator in serous and mucinous ovarian tumors

The prognostic significance of periodic acid-Schiff (PAS) stain in 112 serous: 43 benign, 25 borderline and 44 malignant cystadenomas: and in 106 mucinous: 60 benign, 32 borderline and 14 malignant cystadenomas of the ovary were investigated. The amount of positively stained mucin was estimated morphometrically. The outcome of most patients with benign or borderline lesion was good. One patient with benign mucinous cystadenoma died, however, of pseudomyxoma peritonei and another patient with borderline mucinous cystadenoma died of peritoneal carcinosis. Other patients were alive and free of the disease after a follow-up of 1-14 years, or had died of causes unrelated to the ovarian disease. Abundant PAS positive mucin predicted a longer survival both in serous and in mucinous malignant tumors. The 5-year survivals for the serous cystadenocarcinomas with and without PAS positive mucin were 21% and 13%, respectively (not statistically significant). For mucinous cystadenocarcinomas with mucin value over and below the median, the 5-year survival rates were 57% and 14%, respectively (P less than 0.10). High PAS positivity in both serous and mucinous cystadenocarcinomas clearly indicated better prognosis, although statistical significance was not achieved. Thus, further studies are needed for final evaluation of the prognostic significance of the PAS stain in these ovarian tumors.

O-acylated sialic acid variants in mucinous tumours of the ovary

O-acylated sialic acid variants (site 8) can be demonstrated histochemically by the PB/KOH/PAS method. They are secreted by goblet cells of the lower gastrointestinal tract, by colorectal adenocarcinomas, and by their metastases. Since the metastases are positive only when the primary tumour is positive, O-acylated sialomucins can be considered to be specific markers of colorectal adenocarcinomas if identified in metastases of a tumour of unknown origin. In our histochemical study we evaluated 29 mucinous cystomas of the ovary (23 benign and 6 malignant). We found that six cases were positive to PB/KOH/PAS. The positivity was observed in a limited number of cells and only in areas which presented an intestinal type epithelium. It was also more evident in malignant cystomas than in benign ones. We therefore think that the PB/KOH/PAS positivity can not only be considered a marker of colorectal adenocarcinomas, but also of all neoplasms which originate from an intestinal epithelium or appear to an "intestinal type epithelium".

Histogenesis of Brenner tumors, II: histochemistry and CEA

The histochemical characteristics of 21 benign Brenner tumors were studied. The mucins associated with these tumors are of transitional cell origin and do not represent a secondary metaplasia of transitional to intestinal-type epithelium. The goblet and ciliated columnar cells associated with the proliferative Brenner tumor are thought to represent a parallel mucinous metaplasia from celomic epithelium. Thirteen of the 16 benign Brenner tumors and the one proliferative Brenner tumor were found to contain carcinoembyronic antigen (CEA), indicating an additional antigenic similarity to transitional epithelium.

Histochemistry of glycoconjugates of pleomorphic adenomas of minor salivary glands, with special reference to glycocalyx of tubular areas

Histochemical characterization of glycoconjugates elaborated by palatal pleomorphic adenomas showed that glycoproteins, glycosaminoglycans, and perhaps glycolipids were present in both the "epithelial" and "connective tissue" components of these tumors, as well as in the distinct glycocalyx present in the luminal surface of tubular and cystic areas.

The histochemistry of complex carbohydrates in the ovarian follicles of adult mice

In the ovarian follicles of adult mice, complex carbohydrate-containing structures have been studied by means of light microscopic histochemical methods. In the ovarian follicles, the zona pellucida of oocytes, follicular fluid and intercellular matrix of the granulosa layer are found to exhibit positive reactions for complex carbohydrates with 1,2-glycol and acidic groups and alpha-D-mannosyl and alpha-D-glucosyl residues. The present histochemical analyses have revealed that the complex carbohydrates common to the three types of the structures are hyaluronic acid, sulfated glycosaminoglycans other than isomeric chondroitin sulfates and neutral glycoproteins and that sialic acid is a particular moiety of the zona pellucida, whereas isomeric chondroitin sulfates being that of the follicular fluid and intercellular matrix of the granulosa layer. The histophysiological activities of the carbohydrate-containing structures have been discussed with special reference to their histochemical properties determined in the present study.

Value of histochemical reactions for mucosubstances in the diagnosis of certain pathological conditions of the colon and rectum

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