Objective: To investigate the expression of Snail, a newly discovered inhibitory transcription factor, and E-cadherin in pancreatic carcinoma (PC) and clinical significance thereof.
Methods: Immunohistochemistry was used to examine the expression of Snail and E-cadherin in 56 specimens of PC obtained during operation. PC cells of the line of Panc-1 and transfected with pCMV-Tag2B-Snail, a eucaryotic expression vector coding Snail, so as to obtain a stable clone named Panc-1-Snail. RT-PCR was used to detect the mRNA expression of Snail gene in the Panc-1-Snail cells. Immunofluorescence technique and Western blotting were used to detect the expression of E-cadherin in the Pan-1-Snail cells. Transwell cell culture chamber method was used to examine the invasion ability of the Panc-1-and Panc-1-Snail cells.
Results: Twenty of the 56 PC specimens (36%) were positive in Snail, mainly located in the nuclei. Seventeen of the 20 Snail-positive PC specimens were with and 3 without lymph node metastasis (P = 0.006); and 7 of the 8 PC specimens with lymph node metastasis were Snail-positive and only 1 was Snail-negative (P = 0.001). Twenty-six PC specimens showed low expression of E-cadherin with remarkable heterogeneity. Of the 20 Snail-positive PC specimens 13 showed low expression of E-cadherin and only 7 showed normal expression of E-cadherin; and 13 of the 36 Snail-negative PC specimens showed low expression of E-cadherin (P = 0.038). RT-PCR showed strong Snail mRNA expression in the Pan-1 cells. Both Western blotting and immunofluorescence technique showed the depression of E-cadherin expression. The Transwell chamber test showed that the number of penetrating Pan-1-Snail cells after 24-hour incubation was (174 +/- 8)/200X field of view, significantly greater than that of the Pan-1 cells [(96 +/- 4)/200X field of view, P < 0.01].
Conclusion: Re-expressed in PC and accelerating the invasion of PC through depressing E-cadherin expression, Snail may present a new marker for predicting the aggressiveness of PC.