Abstract： Objective To observe the inhibitory effect on lymph node metastasis of pancreatic cancer and lymphangiogenesis in mice by injection of KAll gene within xenograft tumor.Methods Pancreatic cancer cell line MiaPaCa-2 wag used to construct the nude mice models bearing tumors,then the mice were divided into normal saline group,Ad group and Ad-KAI1 group.Since the successful model construction,normal saline,Ad,Ad-KAI1 was injected every week for 3 times,respectively in the three groups,then the tumor size was documented.50 d after model construction,the tumor and enlarged lymph nodes were collected and subjected to pathological exam,and the expression of LYVE-1 and the MLVD in xenograft tumor was detected by immunohistochemistry.Results Two weeks after MiaPaCa-2 implantation,the model was 100％ successfully constructed.The growth curve of subcutaneous tumor among 3 groups was not statistically significant (P＞0.05) ; the weights of subcutaneous tumor in the 3 groups were (2514.4 ±351.3),(2466.1 ± 295.5),(2294.4±255.4) mg after 50 d,and the difference among the 3 groups was not statistically significant (P ＞0.05).Enlarged lymph nodes metastasis was observed in 8 mice (80％) in normal saline group,and 20 lymph nodes were collected,with 2.0 lymph nodes per mice; and enlarged lymph nodes metastasis was observed in 7 mice (70％) in Ad group,and 15 lymph nodes were collected,with 1.5 lymph nodes per mice; while enlarged lymph nodes metastasis was observed in 4 mice (40％) in Ad-KAI1 group,and 6 lymph nodes were collected,with 0.6 lymph nodes per mice.All the lymph nodes were confirmed to be metastasis of the primary tumor after pathologic exam.The difference of lymph nodes metastasis,number of lymph nodes metastasis per mice among the 3 groups was statistically significant (F =3.14,3.35,P ＜ 0.05).The MLVD of subcutaneous tumor among the 3 groups was (18.70 ± 5.60),(19.40 ± 4.58),(9.80 ±4.10)/400 times magnification,the MLVD of Ad-KAI1 group was significantly lower than those in normal saline group and Ad group (F10.76,11.36,P ＜ 0.05),but the difference between normal saline group and Ad group was not statistically significant.Conclusions KAI1 can inhibit the lymph node metastasis of pancreatic cancer,and the mechanism may be related with decreased lymphangiogenesis and reduced lymphatic vessel density.