Plasma sialic acid as a marker of the effect of the treatment on metastatic colorectal cancer

Association of Serum Proteases and Acute Phase Factors Levels with Survival Outcomes in Patients with Colorectal Cancer

Colorectal cancer (CRC) represents a substantial burden on global healthcare, contributing to significant morbidity and mortality worldwide. Despite advances in screening methodologies, its incidence remains high, necessitating continued efforts in early detection and treatment. Neoplastic invasion and metastasis are primary determinants of CRC lethality, emphasizing the urgency of understanding underlying mechanisms to develop effective therapeutic strategies. This study aimed to explore the potential of serum biomarkers in predicting survival outcomes in CRC patients, with a focus on cathepsin B (CB), leukocytic elastase (LE), total sialic acid (TSA), lipid-associated sialic acid (LASA), antitrypsin activity (ATA), C-reactive protein (CRP), and cystatin C (CC). We recruited 185 CRC patients and 35 healthy controls, assessing demographic variables, tumor characteristics, and 7 serum biomarker levels, including (1) CB, (2) LE, (3) TSA, (4) LASA, (5) ATA, (6) CRP, and (7) CC. Statistical analyses included ANOVA with Tukey's post hoc tests and MANOVA for continuous variables. Student's t-test was used for dependent samples, while non-parametric tests like Mann-Whitney U and Wilcoxon signed-rank tests were applied for variables deviating from the normal distribution. Categorical variables were assessed using chi-square and Kruskal-Wallis tests. Spearman's rank correlation coefficient was utilized to examine variable correlations. Survival analysis employed the Kaplan-Meier method with a log-rank test for comparing survival times between groups. Significant associations were observed between CB (p = 0.04), LE (p = 0.01), and TSA (p = 0.008) levels and survival outcomes in CRC patients. Dukes' classification stages also showed a significant correlation with survival (p = 0.001). However, no significant associations were found for LASA, ATA, CRP, and CC. Multivariate analysis of LE, TSA, and ATA demonstrated a notable correlation with survival (p = 0.041), notwithstanding ATA's lack of significance in univariate analysis (p = 0.13). CB, LE, and TSA emerged as promising diagnostic markers with prognostic value in CRC, potentially aiding in early diagnosis and treatment planning. Further research is needed to validate these findings and explore additional prognostic indicators.

Diagnostic usefulness of selected proteases and acute phase factors in patients with colorectal adenocarcinoma

BACKGROUND

Uncontrolled growth and loss of control over basic metabolic functions, leading to invasive proliferation and metastases, are the salient traits of malignant tumors in general and colorectal cancer in particular. Invasion and metastases hinder effective tumor treatment. While surgical techniques and radiotherapy can be used to remove tumor focus, only chemotherapy can eliminate dispersed neoplastic cells. However, the efficacy of the latter method is limited in the advanced stages of the disease. Therefore, recognition of the mechanisms involved in neoplastic cell spreading is indispensable for developing effective therapies.

AIM

To use a number of biomarkers involved in cancer progression and identify a panel that could be used for effective early diagnosis.

METHODS

We recruited 185 patients with colorectal adenocarcinoma (98 men, 87 women with median age 63). Thirty-five healthy controls were sex and age-matched. Dukes’ staging was as follows: A = 22, B = 52, C = 72, D = 39. We analyzed patients' blood serum before surgery. We determined: (1) Cathepsin B (CB) with Barrett's method (fluorogenic substrate); (2) Leukocytic elastase (LE) in a complex with alpha 1 trypsin inhibitor (AAT) using the immunoenzymatic MERCK test; (3) Total sialic acid (TSA) with the colorimetric periodate-resorcinol method; (4) Lipid-bound sialic acid (LASA) with the colorimetric Taut's method; and (5) The antitrypsin activity (ATA) employing the colorimetric test.

RESULTS

In patients, the values of the five biochemical parameters were as follows: CB = 16.1 ± 8.8 mU/L, LE = 875 ± 598 µg/L, TSA = 99 ± 31 mg%, LASA = 0.68 ± 0.33 mg%, and ATA = 3211 ± 1504 U/mL. Except for LASA, they were significantly greater than those of controls: CB = 11.4 ± 6.5 mU/L, LE = 379 ± 187 µg/L, TSA = 71.4 ± 15.1 mg%, LASA = 0.69 ± 0.28 mg%, and ATA = 2016 ± 690 U/mL. For CB and LASA, the differences between the four Dukes’ stages and controls were not statistically significant. The inter-stage differences for CB and LASA were also absent. The receiver operating characteristic (ROC) analysis revealed the potential diagnostic value of CB, TSA, and ATA. The area under ROC, sensitivity, and specificity for these three parameters were: 0.85, 72%, 90%; 0.75, 66%, 77%; and 0.77, 63%, 84%, respectively. The sensitivity and specificity for the three-parameter panel CB-TSA-ATA were equal to 88.2% and 100%, respectively.

CONCLUSION

The increased value of CB, TSA, and ATA parameters are associated with tumor biology, invasion, and metastasis of colorectal cancer. The presented evidence suggests the potential value of the CB-TSA-ATA biochemical marker panel in early diagnostics.

NEU4 inhibits motility of HCC cells by cleaving sialic acids on CD44

Hepatocellular carcinoma (HCC) is an extremely metastatic tumor. Sialic acids (SAs) are associated with cancer development and metastasis. NEU4 is a sialidase that removes SAs from glycoconjugates, while the function of the NEU4 in HCC has not been clearly explored. In our research, we found the NEU4 expression was significantly down-regulated in HCC tissues, which was correlated with high grades and poor outcomes of HCC. The NEU4 expression could be regulated by histone acetylation. In the functional analysis of NEU4, the cell motility was inhibited when NEU4 was overexpressed, and restored when NEU4 expression was down-regulated. Similarly, NEU4 over-expressed HCC cells showed less metastasis in athymic nude mice. Further study revealed that NEU4 could inhibit cell migration by enzymatic decomposition of SAs. Our results verified a NEU4 active site (NEU4E235) and overexpressing inactivates NEU4E235A that weakens the inhibition ability to cell migration. Further, 70 kinds of specific interacting proteins of NEU4 including CD44 were identified through mass spectrum. Moreover, the α2,3-linked SAs on CD44 were decreased and the hyaluronic acid (HA) binding ability was increased when NEU4 over-expressed or activated. Additionally, the mutation of CD44 with six N-glycosylation sites showed less sensibility to NEU4 on cell migration compared with wild-type CD44. In summary, our results revealed the mechanism of low expression of NEU4 in HCC and its inhibitory effect on cell migration by removal of SAs on CD44, which may provide new treatment strategies to control the motility and metastasis of HCC.

Microglial activatory (immunoreceptor tyrosine-based activation motif)- and inhibitory (immunoreceptor tyrosine-based inhibition motif)-signaling receptors for recognition of the neuronal glycocalyx

Microglia sense intact or lesioned cells of the central nervous system (CNS) and respond accordingly. To fulfill this task, microglia express a whole set of recognition receptors. Fc receptors and DAP12 (TYROBP)-associated receptors such as microglial triggering receptor expressed on myeloid cells-2 (TREM2) and the complement receptor-3 (CR3, CD11b/CD18) trigger the immunoreceptor tyrosine-based activation motif (ITAM)-signaling cascade, resulting in microglial activation, migration, and phagocytosis. Those receptors are counter-regulated by immunoreceptor tyrosine-based inhibition motif (ITIM)-signaling receptors, such as sialic acid-binding immunoglobulin superfamily lectins (Siglecs). Siglecs recognize the sialic acid cap of healthy neurons thus leading to an ITIM signaling that turns down microglial immune responses and phagocytosis. In contrast, desialylated neuronal processes are phagocytosed by microglial CR3 signaling via an adaptor protein containing an ITAM. Thus, the aberrant terminal glycosylation of neuronal surface glycoproteins and glycolipids could serve as a flag for microglia, which display a multitude of diverse carbohydrate-binding receptors that monitor the neuronal physical condition and respond via their ITIM- or ITAM-signaling cascade accordingly.

Effect of Neem (Azadirchta indica) on serum glycoprotein contents of rats administered 1,2 dimethylhydrazine

The present study was designed to investigate the effects of aqueous Azadirchta Indica leaf extract (AAILE) on serum glycoprotein contents and tumor incidence rate in colon of rats subjected to Dimethylhydrazine (DMH) treatment. Forty rats were divided equally and randomly into four groups viz., Group I (normal control), Group II (DMH-treated), Group III (AAILE) and Group IV (DMH + AAILE treated). Group II and IV animals were injected subcutaneously every week with DMH (30 mg/kg b.wt.) for two durations of 10 and 20 weeks. AAILE was given orally three times a week on alternate days (100 mg/kg b.wt.) to animals belonging to groups III and IV. Blood samples were drawn from all the animals by ocular vein puncture every month for the estimation of Total Sialic Acid (TSA) and Lipid Bound Sialic Acid (LSA), which served as markers for the cancer. No incidence of tumor was recorded in the animals given DMH treatment for 10 weeks. However, DMH treatment for 20 weeks showed 100% tumor incidence. Animals treated with DMH for both the time durations showed a significant increase in the levels of TSA in comparison to normal control, which however were decreased significantly following AAILE supplementation. There was no significant difference between LSA levels of DMH-treated animals and normal controls. The present study suggested that supplementation of AAILE in cancer-bearing animals attenuates considerably the molecular events that initiate the development of tumors.

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.

Characterization of the Reaction between Sialic Acid (N-Acetylneuraminic Acid) and Hydrogen Peroxide

In a previous report, we had demonstrated the antioxidant activity of the sialic acid N-acetylneuraminic acid (Neu5Ac, NANA). This activity can counteract the cytotoxicity of hydrogen peroxide (H2O2), and the antitoxicity is a result of a direct chemical reaction, whereby NANA reduces H2O2 in the culture media. The influence of the potential of hydrogen (pH) and temperature in this reaction was investigated. The reaction velocity is remarkably less at low pH and/or low temperature, but it increases with these parameters. Furthermore, the reaction product generated in the slow reaction under acidic conditions (pH 3.1) was analyzed. We detected 4-(acetylamino)-2,4-dideoxy-D-glycero-D-galacto-octonic acid (ADOA) as the decarboxylation product of NANA; this is the same product we previously obtained in a faster reaction at neutral pH (pH 7.5). Furthermore, ADOA was generated not only from the reaction with the NANA monomer but also from that with alpha(2-->8) homodimer of NANA (DP2). Thus, it can be considered that the reaction between NANA and H2O2 can occur under various pH conditions and for NANA residues in a glycochain.

Modification of oligosaccharides by reactive oxygen species decreases sialyl lewis x-mediated cell adhesion

Modification of cell surface oligosaccharides by reactive oxygen species (ROS) and the biological effect of such modifications on cell adhesion were investigated. Treatment of HL60, a human promyelocyte leukemia cell line, with ROS, generated by a combination of hypoxanthine and xanthine oxidase (HX/XO), decreased the sialic acid content on the cell surface, as indicated by a flow cytometric analysis involving sialic acid-specific lectins, and a concomitant increase of free sialic acid was observed in the supernatant. A cell adhesion assay showed that the HX/XO treatment of HL60 cells decreases their capability of binding to human umbilical vein endothelial cells (HUVEC), probably because of an impairment of the interaction involving E-selectin, whereas the decrease in the binding was canceled by the addition of superoxide dismutase (SOD) and catalase. In fact, cell surface sialyl lewis x (sLe x), but not lewis x (Le x), was decreased by HX/XO treatment. Thus, it is more likely that the impaired interaction is based on diminished levels of the selectin ligand. Cleavage of sialic acid by ROS was further verified by the degradation of 4MU-Neu5Ac by HX/XO in the presence of hydrogen peroxide and iron ion. These results indicate that glycosidic linkage of sialic acid is a potential target for superoxide and other related ROS. It is well known that ROS cause cellular damages such as lipid peroxidation and protein oxidation, but, as suggested by the findings reported in the literature, ROS may also regulate cell adhesion via the structural alteration of sialylated oligosaccharides on the cell surface.

Evaluation of serum sialic acid, sialyltransferase and sialoproteins in oral cavity cancer

OBJECTIVE

Altered glycosylation of glycoconjugates is among the important molecular changes that accompany malignant transformation. The aim of our study was to investigate clinical usefulness of circulatory levels of sialic acid, sialoproteins and sialyltransferase for early diagnosis and management of oral cavity cancer (OC) patients.

MATERIALS AND METHODS

Blood samples collected from 210 untreated OC patients, 100 patients with oral precancerous conditions (OPC) and 100 healthy males. OC patients were followed after initiation of anticancer treatment and 394 follow-up samples were also collected. Serum sialic acid levels were measured spectrophotometrically. Sialyltransferase activity was analysed using radioassay. Alpha 2-6 sialoproteins were isolated using lectin affinity chromatography.

RESULTS

Serum levels of free, protein bound and total sialic acid as well as their ratio with total proteins were significantly elevated in untreated OC patients compared with healthy individuals, patients with OPC as well as complete responders (CR). Levels of the markers were comparable between untreated OC patients and non-responders. We observed positive correlation between serum levels of the markers and extent of malignant disease. Serum sialyltransferase activity showed significant elevations in OC patients compared with the controls (P<0.001), patients with OPC (P<0.05) and CR (P<0.05). Higher sialic acid levels in OC patients at the time of diagnosis showed poor survival. The changes in serum proteins with terminal alpha 2-6 sialic acid correlated well with the alterations in the levels of sialic acid forms and sialyltransferase activity.

CONCLUSION

Our results confirmed the elevations in sialic acid and sialyltransferase levels in OC patients and suggested potential utility of these parameters in prognostication and treatment monitoring of this neoplasm. The alterations in these parameters in circulation were in accordance with the changes in alpha 2-6 sialylated proteins.

Separation methods for sialic acids and critical evaluation of their biologic relevance

Sialic acids are biosynthesized by almost all organisms as a 9-carbon carboxylated monosaccharide and are integral components of glycoconjugates. More than 40 naturally occurring sialic acid derivatives of the three main forms of sialic acids, the N-acetyl- and N-glycolylneuraminic acid and 2-keto-3-deoxy-nonulosonic acid have been identified. Due to the great importance of sialic acids as key mediators in a plethora of cellular events, including cell-cell recognition and cell-matrix interactions, their analysis in biologic samples is useful for a deeper understanding of the various (patho)physiological processes and of value in disease diagnosis and monitoring. In this review we summarize the methodology developed to isolate and liberate sialic acids from biologic samples as well as the chromatographic, electromigration and hyphenated techniques available for their separation and analysis. A critical evaluation of the biological relevance of the results obtained by analyzing sialic acids in biologic samples is also presented.

Occurrence of sialic acids in healthy humans and different disorders

Sialic acid (SA), N-acetylated derivatives of neuraminic acid, play a central role in the biomedical functioning of humans. The normal range of total sialic acid (TSA) level in serum/plasma is 1.58-2.22 mmol L-1, the free form of SA only constituting 0.5-3 mumol L-1 and the lipid-associated (LSA) forms 10-50 mumol L-1. Notably, considerably higher amounts of free SA are found in urine than in serum/plasma (approximately 50% of the total SA). In inherited SA storage diseases such as Salla's disease, SA levels are elevated many times over, and their determination during clinical investigation is well established. Furthermore, a number of reports describe elevated SA levels in various other diseases, tentatively suggesting broader clinical utility for SA markers. Increased SA concentrations have been reported during inflammatory processes, probably resulting from increased levels of richly sialylated acute-phase glycoproteins. A connection between increased SA levels and elevated stroke and cardiovascular mortality risk has also been reported. In addition, SA levels are slightly increased in cancer, positively correlating with the degree of metastasis, as well as in alcohol abuse, diabetes, chronic renal failure and chronic glomerulonephritis. Several different mechanisms are assumed to underlie the elevated SA concentrations in these disorders. The apparent non-specificity of SA to a given disease limits the potential clinical usefulness of SA determination. In addition, some non-pathological factors, such as aging, pregnancy and smoking, may cause changes in SA concentrations. The absolute increases in SA levels are also rather small (save those in inherited SA storage disorders); this further limits the clinical potential of SA as a marker. Tentatively, SA markers might serve as adjuncts, when combined with other markers, in disease screening, disease progression follow-up, and in the monitoring of treatment response. To become clinically useful, however, the existing SA determination assays need to be considerably refined to reduce interferences, to be specific for certain SA forms, and to be more easy to use.