Plasma lipid-bound sialic acid alterations in neoplastic diseases

Aberrant sialylation in ovarian cancers

Sialylation (the covalent addition of sialic acid to the terminal end of glycoproteins or glycans), tightly regulated cell- and microenvironment-specific process and orchestrated by sialyltransferases and sialidases (neuraminidases) family, is one of the posttranslational modifications, which plays an important biological role in the maintenance of normal physiology and involves many pathological dysfunctions. Glycans have roles in all the cancer hallmarks, referring to capabilities acquired during all steps of cancer development to initiate malignant transformation (a driver of a malignant genotype), enable cancer cells to survive, proliferate, and metastasize (a consequence of a malignant phenotype), which includes sustaining proliferative signaling, evading growth suppressor, resisting cell apoptosis, enabling replicative immortality, inducing angiogenesis, reprogramming of energy metabolism, evading tumor destruction, accumulating inflammatory microenvironment, and activating invasion and accelerating metastases. Regarding the important role of altered sialylation of cancers, further knowledge about the initiation and the consequences of altered sialylation pattern in tumor cells is needed, because all may offer a better chance for developing novel therapeutic strategy. In this review, we would like to update alteration of sialylation in ovarian cancers.

Serum sialylation changes in cancer

Cancer is a major cause of death in both developing and developed countries. Early detection and efficient therapy can greatly enhance survival. Aberrant glycosylation has been recognized to be one of the hallmarks of cancer as glycans participate in many cancer-associated events. Cancer-associated glycosylation changes often involve sialic acids which play important roles in cell-cell interaction, recognition and immunological response. This review aims at giving a comprehensive overview of the literature on changes of sialylation in serum of cancer patients. Furthermore, the methods available to measure serum and plasma sialic acids as well as possible underlying biochemical mechanisms involved in the serum sialylation changes are surveyed. In general, total serum sialylation levels appear to be increased with various malignancies and show a potential for clinical applications, especially for disease monitoring and prognosis. In addition to overall sialic acid levels and the amount of sialic acid per total protein, glycoprofiling of specific cancer-associated glycoproteins, acute phase proteins and immunoglobulins in serum as well as the measurements of sialylation-related enzymes such as sialidases and sialyltransferases have been reported for early detection of cancer, assessing cancer progression and improving prognosis of cancer patients. Moreover, sialic-acid containing glycan antigens such as CA19-9, sialyl Lewis X and sialyl Tn on serum proteins have also displayed their value in cancer diagnosis and management whereby increased levels of these factors positively correlated with metastasis or poor prognosis.

Evaluation of lipid-bound sialic acid (LSA) as a tumor marker

The objective of this study is the evaluation of serum levels of lipid-bound sialic acid (LSA) as a of marker cancer. This is a case-control study, and the levels of LSA were determined with blinded duplicates of cases and controls. Histologic verification of all cancer cases was used to confirm the diagnosis. The study included 135 patients with cancer (breast carcinoma, head and neck squamous cell carcinoma, lung cancer and gastrointestinal cancer) and 95 controls (57 normal subjects and 38 with chronic non-malignant diseases). Marker determination was done by the spectrophotometric procedure of Katopodis with resorcinol. The mean LSA level in the 57 healthy individuals was 15.09 mg/dl (95% C.I., 13.51-16.67), in the entire control group of 95 non-tumoral individuals it was 19.21 mg/dl (17.18-21.24), and in the 135 cancer patients it was 26.64 mg/dl (24.42-28.87). There was a statistically significant difference between patients with chronic non-tumoral diseases and healthy individuals (p<0.001) and also between cancer patients and healthy individuals (p<0.001), but not between cancer patients and patients with chronic non-tumoral diseases (p>0.05). The mean LSA serum values related to tumor site were (mg/dl): breast cancer, 21.49; gastrointestinal tumors, 28.45; head and neck cancer, 28.61 and lung cancer, 32.54. The means according to clinical stage were: complete remission, 18.50, significantly higher than the healthy controls (p<0.05); local disease, 23.50 (p<0.01); locoregional disease, (p<0.05); local disease, 23.50 (p < 0.01); locoregional disease, 27.21 (p < 0.001); metastatic disease, 34.49 (p < 0.001), and relapses, 20.87 (p<0.05). When comparing patients with clinically active cancer with healthy persons, the estimated cutoff value was 19.1 mg/dl, with a sensitivity of 74.7% and a specificity of 74.7%. We conclude that LSA values increase in cases of clinically active cancer and decrease in complete remission. LSA is of great value as a tumor marker in the diagnosis of disease extent.

Sialic acids: biomarkers in endocrinal cancers

Sialylations are post translational modification of proteins and lipids that play important role in recognition, signaling, immunological response and cell-cell interaction. Improper sialylations due to altered sialyl transferases, sialidases, gene structure and expression, sialic acid metabolism however lead to diseases and thus sialic acids form an important biomarker in disease. In the endocrinal biology such improper sialylations including altered expression of sialylated moieties have been shown to be associated with disorders. Cancer still remains to be the major cause of global death and the cancer of the endocrine organs suffer from the dearth of appropriate markers for disease prediction at the early stage and monitoring. This review is aimed at evaluating the role of sialic acids as markers in endocrinal disorders with special reference to cancer of the endocrine organs. The current study is summarized under the following headings of altered sialylations in endocrinal cancer of the (i) ovary (ii) pancreas (iii) thyroid (iv) adrenal and (v) pituitary gland. Studies in expression of sialic acid in testis cancer are limited. The future scope of this review remains in the targeting of endocrinal cancer by targeting altered sialylation which is a common expression associated with endocrinal cancer.

Protective role of Withaferin-A on red blood cell integrity during 7,12-dimethylbenz[a]anthracene induced oral carcinogenesis

The aim of the present study was to investigate the protective effect of Withaferin-A on red blood cell integrity during 7,12-dimethylbenz[a]anthracene (DMBA) induced oral carcinogenesis. The protective effect of Withaferin-A was assessed by measuring the status of glycoconjugates, membrane bound enzyme activity and red blood cell osmotic fragility. Oral squamous cell carcinoma was induced in the buccal pouch of Syrian golden hamsters by painting with 0.5% DMBA in liquid paraffin thrice a week for 14 weeks. The levels of glycoconjugates, membrane bound enzyme activity, osmotic fragility and thiobarbituric acid reactive substances (TBARS) were analyzed by using specific colorimetric methods. We observed 100% tumor formation in DMBA painted hamsters. Increase in plasma glycoconjugates at the expense of red blood cell membrane glycoconjugates levels were observed in DMBA painted hamsters as compared to control hamsters. Erythrocytes from DMBA painted hamsters were more fragile than those from control hamsters. The activity of membrane bound enzyme (Na(+) K(+) ATPase) decreased whereas TBARS level was increased in DMBA painted hamsters as compared to control hamsters. Oral administration of Withaferin-A at a dose of 20 mg kg(-1) bw significantly prevented the tumor formation as well as normalized the biochemical variables in DMBA painted hamsters. Our results thus demonstrate the protective effect of Withaferin-A on red blood cell integrity during DMBA induced oral carcinogenesis.

Serum total sialic acid in differential diagnostics of jaundice caused by malignant and nonmalignant diseases: a ROC curve analysis

The purpose of this study was to evaluate the usefulness of serum total sialic acid (SA) for discrimination of malignant and nonmalignant jaundice. Serum SA concentration and its ratio with total protein (SA/TP) were determined in 55 patients with jaundice: 25 malignant and 30 nonmalignant. SA was estimated by enzymatic method. Serum total SA and the ratio SA/TP were significantly higher in malignant than in nonmalignant jaundice. Diagnostic sensitivity of SA and the ratio of SA/TP in both types of jaundice reached the value of 95.8%. The specificity, positive and negative predictive values, and efficiency of SA and SA/TP were higher in malignant than in nonmalignant jaundice. Areas under ROC curves for SA and the ratio of SA/TP in malignant jaundice were higher than in nonmalignant, but there were not statistically significant differences. SA levels and the ratio of SA/TP do not have the ability to discriminate between these types of jaundice.

Correlation between the Serum Values of Soluble Intercellular Adhesion Molecule-1 and Total Sialic Acid Levels in Patients with Breast Cancer

BACKGROUND

In this study, we aimed to investigate serum total sialic acid (TSA) and soluble intracellular adhesion molecule-1 (sICAM-1) levels in breast cancer patients to find a correlation with the cancer stage.

METHODS

The parameters from sera of 61 patients with breast cancer were measured. The concentrations of serum sICAM-1 and TSA were measured in serum samples from 61 patients with breast cancer and 25 healthy control subjects using enzyme-linked immunoassay and thiobarbituric acid method.

RESULTS

Mean serum sICAM-1 and TSA levels were significantly higher in the total patient group than in the control group (p < 0.001). Thus, the correlation between TSA and sICAM-1 became more significant in metastatic breast cancer. There were significant positive correlations between TSA and sICAM-1 in stage I+II (r = 0.59, p < 0.05), stage III (r = 0.47, p < 0.05), and stage IV (r = 0.89, p < 0.01), and total patient group (r = 0.56, p < 0.001).

CONCLUSION

SerumsICAM-1 and TSA levels were higher in patients with breast cancer, than that of the control group, and also in the metastatic breast cancer group. Significant correlations between serum sICAM-1 and TSA may reflect the similar function of these molecules as adhesion molecules, and their roles in the carcinogenesis of breast cancer as well as metastasis.

Clinical evaluation of serum concentrations of intercellular adhesion molecule-1 in patients with colorectal cancer

AIM: To investigate the correlation between the serum soluble intercellular adhesion molecule-1 (sICAM-1) and the clinicopathologic features and to evaluate the possible prognostic significance of sICAM-1 concentration in colorectal cancer.

METHODS: A total of 56 patients (mean age 57.3 years) having transitional cell carcinoma of the colorectal and 25 control patients (mean age 42.6 years) were enrolled in the study. The serum samples of the patients were obtained on the day before surgery. Sera were obtained by centrifugation, and stored at -80°C until assay. Serum concentrations of ICAM-1 were measured with enzyme-linked immunoassay. Differences between the two groups were analyzed by Student’s t-test.

RESULTS: No significant increase of serum sICAM-1 could be demonstrated in the Dukes A₁ patients (352.63 ± 61.82 μg/L) compared to the control group (345.72 ± 49.81 μg/L, P>0.05), Dukes A₁ patients (352.63 ± 61.82 μ g/L) compared to Dukes A_2,3 patients (491.17 ± 86.36 μg/L, P < 0.05). Furthermore, the patients with Dukes B had significantly higher serum concentrations of sICAM-1 than those of the control group (496.82 ± 93.04 μg/L vs 345.72 ± 49.81 μg/L, P < 0.01). Compared with Dukes A_2,3, B colorectal cancer patients, patients with more advanced clinical stage (Dukes C and D) had higher levels of sICAM-1 (743.68 ± 113.74 μg/L vs 491.17 ± 86.36 μg/L and 496.82 ± 93.04 μg/L, P < 0.001). The difference was statistically significant in sICAM-1 levels between patients with positive lymph node status and those without lymph node involvement (756.25 ± 125.57 μg/L vs 445.62 ± 69.18 μg/L, P < 0.001). Patients with poorly differentiated colorectal cancer had a higher level of sICAM-1 than those with differentiated and highly differentiated cancer (736.49 ± 121.97 μg/L vs 410.23 ± 67.47 μg/L, P < 0.001).

CONCLUSION: In this study, serum ICAM-1 levels were found to be related to tumor presence, clinical stages, and grade. Increased ICAM-1 in patients with colorectal cancer which should be considered when the diagnostic and/or prognostic usefulness of soluble ICAM-1 is to be evaluated. sICAM-1 should prove useful for monitoring malignant disease stage and for evaluating the effectiveness of various therapeutic approaches for colorectal carcinomas.

Serum anti-ganglioside IgM antibodies in soft tissue sarcoma: clinical prognostic implications

PURPOSE

Gangliosides are tumor-associated antigens with many biologic functions, including complex interactions with cytokines and other modulators of the immune system. Serum total ganglioside level may be an ideal surrogate marker to predict tumor burden and response to treatment. Antibodies produced against tumor gangliosides may help predict survival. The purpose of this study is to determine whether the serum total ganglioside levels might predict the tumor burden in patients with soft tissue sarcoma, and whether the augmented anti-ganglioside immunoglobulin M (IgM) response might reflect the clinical outcome of these patients.

METHODS

Serum TG levels were measured in the cryopreserved sera by estimating lipid-associated sialic acids from 97 patients before surgical resection of soft tissue sarcoma and from 39 age- and gender-matched healthy volunteers. All sera were analyzed for IgM titers (expressed natural log) by enzyme-linked immunosorbent assay against eight gangliosides (GM1, GM2, GM3, GD3, GD2, GD1a, GD1b, and GT1b). Cox regression was used for univariate and multivariate analyses of the variables affecting progression-free and overall survival.

RESULTS

Serum TG levels were higher in soft tissue sarcoma patients than in healthy individuals (21.8 + 7.7 vs 16.1 + 2.7 mg/dL; P = 0.001). Larger tumors, high histologic grade, and more advanced stage of disease correlated with higher serum total ganglioside levels (P < 0.05). Anti-ganglioside titers to GM3, GD2, and GT1b were significantly higher in patients with soft tissue sarcoma, whereas anti-GD1a and GD1b titers were significantly higher in healthy subjects. The titers of antibodies against GM1, GM2, and GD3 in patients with soft tissue sarcoma were comparable to those of the healthy individuals. When compared with healthy controls, patients with low-grade tumors had higher titers of anti-GT1b, anti-GM3, and anti-GD2 antibodies, and patients with high-grade tumors had higher titers of anti-GT1b and anti-GD2 antibodies. These data suggest that the predominant gangliosides expressed by sarcomas may include GT1b and GD2. In addition, low-grade tumors may express an immunogenic species of GM3. On both univariate and multivariate analyses, augmented anti-GD1a IgM titers, age > 50 years, and retroperitoneal location were predictive of decreased overall survival, whereas augmented anti-GT1b titers were predictive of improved overall survival.

CONCLUSIONS

Serum TG level may be a useful marker of tumor burden and response to treatment for soft tissue sarcoma. Anti-GD1a and anti-GT1b IgM titers predicted survival and may be of therapeutic and prognostic value in the management of soft tissue sarcoma.

Sialic acid concentration in serum and tissue of endometrial cancer patients

Serum total sialic acid (TSA) level was determined in the group of 45 patients with endometrial neoplasia. Moreover, the sialic acid content in 23 surgically obtained tumor tissue specimens has been estimated. The mean value of serum total sialic acid level of the cancer patients (2.38 mmol/l) was significantly higher (P < 0.0001) than the sialic acid level in the control group (1.52 mmol/l). The elevation of serum total sialic acid level was associated with the burden of the tumor (2.30 mmol/l and 2.68 mmol/l for stages I and II + III, respectively). Tissue sialic acid content showed no significant differences between early and advanced clinical stage of the disease.

Measurement of sialic acid in serum and urine: clinical applications and limitations

Many recent studies have examined the sialic acid content of serum or urine in various pathological states. We have briefly reviewed the substances which contribute to the observed total sialic acid concentration, and given an overview of assay methods used. Three major areas of clinical interest in sialic acid metabolism are discussed. Serum total sialic acid, 'lipid-bound' and 'protein bound' sialic acid have all been proposed as tumour markers; but the usefulness of any of these tests is severely limited by changes due to accompanying inflammatory processes. Serum total sialic acid is not a valuable simple marker of an acute phase response. Urinary free and bound sialic acid measurements should be included in screening protocols for inherited disorders of lysosomal metabolism. Current developments in research and potential applications within the clinical biochemistry laboratory are briefly discussed.