Appearance of high-molecular weight sialoglycoproteins recognized by Maackia amurensis leukoagglutinin in gastric cancer tissues: a case report using 2-DE-lectin binding analysis.

Aberrant expression of sialoglycoconjugates has been thought to play an important role in cancer progression. Our previous lectin-histochemical study showed that overexpression of sialoglycoconjugates recognized by alpha2,3-sialic acid-specific Maackia amurensis leukoagglutinin (MAL) was significantly related to the malignancy of gastric cancer. The present study analyzed the sialoglycoproteins in gastric cancer tissues by 2-dimensional electrophoresis (2-DE) in combination with lectin-binding analysis using MAL. Various MAL-positive sialoglycoproteins were detected in cancer tissues but not in non-cancer tissues. The sialoglycoproteins have a high molecular weight of near 200 kDa and over 200 kDa with different pI values for the two. This suggests that the MAL-positive sialoglycoproteins detected in gastric cancer tissues have high molecular weights and may contain different numbers of alpha2,3-linked sialic acid residues in the carbohydrate moiety.

Histochemical expression of sialoglycoconjugates in carcinoma of the papilla of Vater.

BACKGROUND/AIMS: Cell surface glycosylation changes during oncogenesis and is thought to correlate with the malignant potential of cancers. To investigate the role of sialylation in carcinoma of the papilla of Vater, histochemical analyses were performed using sialic acid-binding lectins, Maackia amurensis leukoagglutinin and Sambucus nigra agglutinin. METHODOLOGY: Thirty-six papillary carcinoma tissues and 8 normal papillary tissues were subjected to lectin-histochemical staining. The relationship between lectin staining characteristics and clinicopathological parameters was statistically analyzed. RESULTS: Epithelial cells of glands in normal tissues were stained with Sambucus nigra agglutinin but not with Maackia amurensis leukoagglutinin. Of 36 papillary carcinoma tissues, 20 showed Maackia amurensis leukoagglutinin-positive staining in cancer cells, whereas all 36 were Sambucus nigra agglutinin-positive in cancer cells. According to Maackia amurensis leukoagglutinin-staining characteristics, the 36 cases were divided into two groups: positive (n=20) and negative (n=16). Statistical analysis indicated that positive staining in cancer cells was frequent in cases of lymph node metastasis (p=0.001) and in cases classified > or = T2 by TNM classification (p=0.036). CONCLUSIONS: Aberrant expression of sialoglycoconjugates recognized by Maackia amurensis leukoagglutinin might participate in lymph node metastasis and in an advanced stage of invasion in carcinoma of the papilla of Vater.