MUC4 and MUC1 Expression in Adenocarcinoma of the Stomach Correlates with Vessel Invasion and Lymph Node Metastasis: An Immunohistochemical Study of Early Gastric Cancer

<div><p>We have previously reported that MUC4 expression is a poor prognostic factor in various carcinomas. Our previous study also showed that MUC1 expression in gastric cancers, including the early and advanced stages is a poor prognostic factor. In the present study, the expression profiles of MUC4 and MUC1 were examined by immunohistochemistry (IHC) using two anti-MUC4 monoclonal antibodies (MAbs), 8G7 and 1G8, and anti-MUC1 MAb DF3 in 104 gastrectomy specimens of early gastric adenocarcinoma with submucosal invasion (pT1b2), including 197 histological subtype lesions. Before the IHC study of the human specimens, we evaluated the specificity of the two MAbs by Western blotting and IHC of two MUC4 mRNA expressing gastric cancer cell lines. MAb 8G7 reacted clearly, whereas MAb 1G8 did not show any reactivity, in either Western blotting or IHC. In the IHC of the gastric cancers, the expression rates of MUC4/8G7 detected by MAb 8G7, MUC4/1G8 detected by MAb 1G8 and MUC1/DF3 detected by MAb DF3 in well differentiated types (70%, 38/54; 67%, 36/54; 52%, 28/54) were significantly higher than those in poorly differentiated types (18%, 10/55; 36%, 20/55; 13%, 7/55) (<em>P</em><0.0001; <em>P</em> = 0.0021; <em>P</em><0.0001), respectively. The MUC4/8G7 expression was related with lymphatic invasion (r = 0.304, <em>P</em> = 0.033). On the other hand, the MUC4/1G8 expression was related with lymphatic invasion (r = 0.395, <em>P</em> = 0.001) and lymph node metastasis (r = 0.296, <em>P</em> = 0.045). The MUC1/DF3 expression was related with lymphatic invasion (r = 0.357, <em>P</em> = 0.032) and venous invasion (r = 0.377, <em>P</em> = 0.024). In conclusion, the expression of MUC4 as well as MUC1 in early gastric cancers is a useful marker to predict poor prognostic factors related with vessel invasion.</p> </div

The difference in antibody specificity between anti-human MUC4 monoclonal antibodies (MAbs), 8G7 and 1G8.

<p>A: MUC4 mRNA was detected in the two gastric cancer cell lines, SNU-16 and NCI-N87. PANC1 and CAPAN1 cells were used as a negative and positive control, respectively. B: Cell lysates of SNU-16 and NCI-N87 were immunoblotted and detected by the indicated antibodies, respectively. A-tubulin served as a loading control. C: Formalin-fixed SNU-16 and NCI-N87 cells were processed for immunocytochemistry using the MAbs, 8G7 and 1G8, respectively. Original magnification ×400.</p

Semiquantitative evaluation of mucin expression in gastric carcinoma for each histological type (negative, none of the carcinoma cells stained; faint, >0% to <5% of carcinoma cells stained; 1+, ≥5% to <25%; 2+, ≥25% to <50%; 3+, ≥50% to <75%; and 4+: ≥75% stained.

<p>The detailed number and percentage of positively stained neoplastic cells using the scoring system were summarized in Table S1. MUC4/8G7, MUC4/1G8 and MUC1/DF3 expressions were were significantly higher in the well differentiated types (pap+tub1) than in the poorly differentiated type (por1+por2) (<i>P</i><0.0001, <i>P</i> = 0.0021 and <i>P</i><0.0001, respectively) (arrows). In tub1, expression rates of MUC4/8G7 and MUC4/1G8 were significantly higher than that of MUC1/DF3 (<i>P</i> = 0.0106 and <i>P</i> = 0.039, respectively) (*1). In por2, the expression rate of MUC4/1G8 was significantly higher than that of MUC4/8G7 (<i>P</i> = 0.0286) or that of MUC1/DF3 (<i>P</i> = 0.0005) (*2). In sig, the expression rate of MUC4/1G8 was significantly higher than that of MUC4/8G7 (<i>P</i> = 0.0158) or that of MUC1/DF3 (sig, <i>P</i> = 0.0019) (*3). In the other histolgical types (pap, tub2, muc and por1), there was no significant difference in the expression rates among MUC4/8G7, MUC4/1G8 and MUC1/DF3.</p

Relationship between expression of MUC4 and MUC1 and lymphatic invasion (ly), venous invasion (v) or lymph node metastasis (N).

<p>Spearman's rank-correlation coefficient.</p

Expression patterns of MUC4/8G7, MUC4/1G8 and MUC1/DF3 in each histological type of gastric carcinoma.

<p>Hematoxylin-eosin (HE) (A), MUC4/8G7 (B), MUC4/1G8 (C) and MUC1/DF3 (D) in papillary adenocarcinoma (pap). HE (E), MUC4/8G7 (F), MUC4/1G8 (G) and MUC1/DF3 (H) in well differentiated tubular adenocarcinoma (tub1). HE (I), MUC4/8G7 (J), MUC4/1G8 (K) and MUC1/DF3 (L) in moderately differentiated tubular adenocarcinoma (tub2). HE (M), MUC4/8G7 (N), MUC4/1G8 (O) and MUC1/DF3 (P) in mucinous carcinomas (muc). HE (Q), MUC4/8G7 (R), MUC4/1G8 (S) and MUC1/DF3 (T) in solid type poorly differentiated adenocarcinoma (por1). HE (U), MUC4/8G7 (V), MUC4/1G8 (W) and MUC1/DF3 (X) in non-solid type poorly differentiated adenocarcinoma (por2). HE (Y), MUC4/8G7 (Z), MUC4/1G8 (a) and MUC1/DF3 (b) in signet-ring cell carcinoma (sig). MUC4/8G7 was expressed in the cytoplasm of pap (B), tub1 (F) and tub2 (J), but not in muc (N), por1 (R), por2 (V) nor sig (Z). MUC4/1G8 was expressed mainly at the cell apexes of pap (C), tub1 (G) and tub2 (K), but not in muc (O), por1 (S) nor por2 (W). MUC4/1G8 expression was seen in the intracytoplasmic mucin substance of sig (a). MUC1/DF3 was expressed mainly at the cell apexes tub2 (L), but not expressed in the cases shown in this figure (D, H, P, T, X and b). Original magnification ×200 (A–H, M–T), ×400 (I–L, U–b).</p

Clinicopathological studies using anti-MUC4 monoclonal antibodies, 8G7 and 1G8.

<p>Clinicopathological studies using anti-MUC4 monoclonal antibodies, 8G7 and 1G8.</p

Correlation among MUC4/8G7, MUC4/1G8 and MUC1/DF3.

<p>Spearman's rank-correlation coefficient.</p