Prognostic values of MUC-1 molecule expressing cytokine receptor-like epitope and DF3 in patients with gastric carcinoma

As recently reported, DF3/MUC-1 molecules having cytokine receptor-like seq uences (CRL) at the extracellular region, are likely to function in signal transduction pathways. To elucidate the functional significance of CRL expr essed on the DF3/MUC1 molecule, immunohistochemical localization of CRL and /or DF3 was investigated in cases of 115 patients with gastric carcinomas, treated by surgical resection. CRL was detected in 65 of 115 patients (56.5 %), DF3 in 85 (73.9%), and both DF3 and CRL in 52 (45.2%). The combined imm unohistochemical analysis of CRL and/or DF3, revealed that simultaneous exp ression of DF3 and CRL (DF3(+)/CRL+) significantly correlated to lymph node metastasis and to blood vessel invasion, and that patients with DF3(+)/CRL +-tumors survived for a significantly shorter period after surgery than did the other three groups (DF3(+)/CRL-, DF3(-)/CRL+, and DF3(-)/CRL-). Multiv ariate analysis showed independent prognostic significance for DF3(+)/CRLexpression (hazard ratio [HR]=2.733, P=0.0085), and surgical cure (HR=4.334 , P=0.003). To investigate the biological role of the simultaneous expressi on of DF3 and CRL, we constructed DF3(-)/CRL+ (NR-MC-38) and DF3(+)/CRL+ (R -MC-38) cells by transducing a mouse colon adenocarcinoma cell line MC-38 e xpressing neither DF3 nor CRL with MUC-1 cDNA containing ten tandem repeats (R-MC-38) or MUC-1 cDNA devoid of tandem repeats (NR-MC-38). R-MC-38 (DF3/CRL+) cells were more invasive than NR-MC-38 (DF3-/CRL+) and MC-38 (DF3-/C RL-) cells. When these transfectants were incubated with pAb CRL, the invas iveness of R-MC-38 (DF3(+)/CRL+) was strikingly elevated over the case with native MC-38 (DF3-/CRL-) and NR-MC-38 (DF3-/CRL+) cells. The pAb CRL-induc ed invasiveness of R-MC-38 cells was inhibited by adding mAb DF3 or CRL pep tides together with pAb CRL. These results suggest that an expression of DF 3/MUC1 is highly associated with cell-invasiveness, and the DF3/MUC1-associ ated invasiveness is amplified by CRL. Thus DF3(+)/CRL+-MUC-1 molecule seem s to be closely involved in a poor prognosis for gastric cancer patients.