Lipid Bound Sialic Acid in Cancer Patients

Total Sialic Acid as a Tumor Marker for Oral Cancer

Serum sialic acid levels were measured in 80 healthy subjects, in 60 patiens with benign tumors and in 110 patients with oral cancer. It was shown that these levels were significantly elevated in oral cancer patients compared to healthy controls and patients with benign tumors (p < 0.01); they were higher in patients with stage III and stage IV disease than in those with stage I and II disease (p < 0.01). However, no difference was observed between healthy controls and stage I and II cancer patients. The results of this study suggest that the determination of sialic acid levels may be of value in the diagnosis of oral cancer, but its usefulness as an adjunct in clinical staging is limited.

Graphic-aided study of metabolic modifications of plasma in cancer using proton magnetic resonance spectroscopy

Proton high-resolution MRS of human plasma allows the rapid detection, on the same spectrum, of many compounds originating from different metabolic pathways. In this paper, we illustrate the modifications of the plasma metabolic profiles recorded by proton NMR spectroscopy in different classes of cancers. These modifications can be easily monitored with graphic aids such as 'star plots' which define for each type of cancer a particular pattern describing the most altered metabolic pathways. By using 'star plots' three types of metabolic patterns have been distinguished: (i) the 'inflammatory' pattern characterized by an increase of glycosylated moieties of glycoproteins; (ii) a 'lipid modified' pattern, characterized by various modifications occurring mainly in the lipid moieties detected by MRS; and (iii) a pattern which is often observed in sarcomas and mainly characterized by an alteration in the N-acetyl glucosamine/N-acetyl neuraminic acid ratio. This study demonstrates the ability of proton MRS of plasma to rapidly detect the occurrence of metabolic modifications brought about by cancer evolution or therapy.

Lipid-associated sialic acid, squamous cell carcinoma antigen, carcinoembryonic antigen, and lactic dehydrogenase levels as tumor markers in squamous cell carcinoma of the head and neck

BACKGROUND

Circulating tumor markers are valuable adjuncts in the management of several malignant lesions, including germ cell tumors and adenocarcinomas of the breast, colon, prostate, and ovary. However (to the authors' knowledge), currently, no serologic markers have been shown to have prognostic value for patients with squamous cell carcinomas of the head and neck (SCCHN).

METHODS

Novel and existing markers were evaluated prospectively in patients with SCCHN: The levels of lipid-associated sialic acids (LASA), squamous cell carcinoma circulating antigen (SCC-Ag), carcinoembryonic antigen (CEA), and lactic dehydrogenase (LDH) were evaluated in 52 patients: 42 with active measurable SCCHN and 10 with no clinical evidence of active disease after treatment (NED).

RESULTS

In patients with active disease, LASA, SCC-Ag, CEA, and LDH were elevated in 71%, 33%, 27%, and 18%, respectively, and in seven patients with distant metastasis (M1) in 100%, 86%, 57%, and 33%, respectively. None of the markers were elevated in the NED group. The incidence and magnitude of LASA and SCC-Ag elevations correlated with the extent of disease (active disease versus NED, Stage III versus IV, T0-3 versus T4 primary lesions, M0 versus M1). LDH and CEA elevations correlated primarily with the presence of distant metastases.

CONCLUSIONS

LASA appears to be a promising sensitive marker of SCCHN, followed in decreasing order of sensitivity by SCC-Ag, CEA, and LDH. Additional study to evaluate the specificity of LASA and its correlation with tumor response to therapy is warranted.

Serum sialic acid levels in patients with oral and maxillofacial malignancy

Serum sialic acid levels were measured using the thiobarbituric acid method in 80 healthy subjects and in 40 patients with benign and 61 with malignant tumors in the oral and maxillofacial region. It was shown that the cancer group had statistically higher sialic acid levels than control group and the group with benign disease (P less than .05), but no significant difference was noted between the normal control group and the patients with benign tumor (P greater than .05). Serum sialic acid levels were significantly higher in the patients with stages III and IV cancer than in those individuals with stage I and II cancer, but no differences were seen between stages I and II, and between stages III and IV cancer patients (P greater than .05). There was also no difference when considering the anatomic site of the malignant lesion. Furthermore, during the serial sialic acid determination in cancer patients before and following treatment, the sialic acid levels usually declined with remission of the disease and increased with recurrence, metastasis, or a poor prognosis. We conclude from this study that the sequential measurement of sialic acid level is particularly useful in monitoring patients with oral cancer, and sialic acid may prove to be a valuable tumor marker in oral and maxillofacial malignancy.

Variations of plasma sialic acid and N-acetylglucosamine levels in cancer, inflammatory diseases and bone marrow transplantation: a proton NMR spectroscopy study

Proton NMR spectroscopy allows the detection in plasma of resonances arising from N-acetyl-glucosamine (NAG) and N-acetyl-neuraminic acid (NANA) which have been shown to be borne by acute phase glycoproteins. These resonances can be identified using 2 different protocols of spectrum acquisition detecting different physical states in the global pool of glycoproteins, ie mobile and less mobile moieties of glycosylated chains. In this study we demonstrate that NMR spectroscopy allows a precise monitoring of the variations of glycosylated residues in cancers, inflammatory processes and bone marrow transplantation. The most important findings are that: i), the distribution of glycosylated residues varies with the origin of the cancerous tissue; ii), the level of these residues is a function of tumor development; iii), the concentrations in NAG and NANA are well correlated with the standard biological parameters of acute phase and leucocyte activation. Proton NMR spectroscopy of glycosylated residues in plasma may offer a new means of monitoring sialic acid in cancer and other pathological conditions.

Serum sialic acid and carcinoembryonic levels in the detection and monitoring of colorectal cancer

Total sialic acid (TSA), total protein (TP), TSA normalized to total TP (TSA/TP), and carcinoembryonic antigen levels were determined in 146 consecutive colorectal patients. These results were compared with results from 73 people with nonmalignant gastrointestinal disease, and with results from 96 normal controls. All malignancies were staged according to the Astler-Coller modification of Dukes' classification for colorectal cancer. All blood samples were drawn before surgical therapy. The TSA/TP ratio for colorectal cancer was 13.4 (mg/gm) in contrast to 12.1 (mg/gm) for pathologic controls, and 9.7 (mg/gm) for normal controls. Student's t test showed a P value less than 0.001 for normal controls and a P value less than 0.001 for pathologic controls. The TSA/TP also showed statistical significance in Dukes A, B2, C, and D subgroups when compared with normal controls. There were only four patients with stage C1 carcinoma, thus statistical analysis would be questionable. In contrast, carcinoembryonic antigen levels showed no significant elevations until Dukes C2 tumors were encountered. These preliminary findings suggest that TSA/TP ratio may detect colorectal cancer patients with less tumor burden and be more beneficial as a tumor marker than CEA for monitoring patients with colorectal cancer.

Evaluation and limitations of the lipid-associated sialic acid test for the detection of human cancer

Previous studies and those of the authors have reported about raised levels of lipid-bound sialic acid (LSA) in sera of patients with various neoplasms. Most authors have used the method of Katopodis and Stock for isolating serum LSA. Because of the discrepancy of the amount of extracted LSA with the content of pure gangliosides in sera reported by other groups the authors analyzed the composition of the extracted LSA by immunochemical approaches. They were able to isolate considerable amounts of glycoproteins containing sialic acid as acid alpha-1-glycoprotein, antitrypsin, haptoglobin, antichymotrypsin, and immunoglobulins from the so-called "LSA" fraction. There is a very strong correlation between the raised LSA levels and the content of acid-alpha-1-glycoprotein in the sera of patients with malignancy. Therefore the term lipid-bound sialic acid applied to this test is misleading, since glycoproteins containing sialic acid are mostly responsible for the high "LSA" levels.

Malignant cell glycoproteins and glycolipids

The cell surface is involved in cell growth and division, cell-cell interaction, communication, differentiation and migration, and other processes likely to be involved in malignant transformation and/or the metastatic spread of cancer. Although there are many alterations of glycoproteins and glycolipids on the malignant cell surface, it is unclear whether these alterations are epiphenomena or an integral part of the malignancy process. This article reviews the recent literature and some earlier studies relevant for understanding emerging concepts and trends with respect to malignant cell glycoconjugates. Emphasis is on structural alterations of the carbohydrate portions of malignant cell glycoproteins and glycolipids and on the enzymes (glycosyltransferases and glycosidases) involved in their metabolism. Practical applications derived from malignant cell glycoconjugate studies are discussed briefly with respect to the diagnosis, staging, monitoring, and treatment of malignant disease. The review concludes by indicating which research areas on malignant cell glycoconjugates are likely to be fruitful in increasing our basic understanding of, and ability to deal effectively with, malignant disease.