OBJECTIVETo establish PEG10 transgenic mice model and study the effect of PEG10 transgene on tumor growth and metastasis in mice.

METHODSThe linearized expression element of pALB-PEG10, which contained mouse albumin promoter, structural gene of PEG10, and polyaenylation signal sequence, was microinjected into 3741 KM mouse fertilized ova. The manipulated embryos were then transplanted into the oviducts of 94 pseudopregnant recipient mice. All the newborn mice were screened by PCR to detect genomic DNA in tail tissue, then PEG10 mRNA and protein expression were detected by RT-PCR and western blot, respectively in the positive mice. Hepatoma cell H22 was subcutaneously inoculated into the right armpit of wild type mice and No.17, No.33 transgenic mice. Tumor size was measured every week. Mice were sacrificed on day 12 and then the tumors were exercised and weighted. Tumors and livers were fixed in formaldehyde and sectioned. The sections were stained with hematoxylin/eosin and examined under microscope. The expression of PEG10 protein was detected with immunohistochemistry method.

RESULTSAmong the 43 off-springs, 3 were positive for tail tissue PEG10 gene examination, PEG10 was successfully expressed in the liver of the randomly selected transgenic mouse. H22 tumor grew faster in all the transgenic mice than in wild type mice. The average size and weight of tumors between the transgenic mice and wild type mice were significantly different (P < 0.05). Most tumors in the transgenic mice invaded the surrounding tissues and showed liver metastasis, PEG10 protein was expressed in liver. In contrast, nearly all the tumors in wild type mice were capsulized and PEG10 was not expressed in liver.

CONCLUSIONOur results showed that the PEG10 gene could be expressed in the liver of the transgenic mice. PEG10 promotes growth, invasion, and metastasis of transplanted H22 tumors in mice.