Adenovirus E1A orchestrates the urokinase-plasminogen activator system and upregulates PAI-2 expression, supporting a tumor suppressor effect

Invasiveness and metastatic potential are the two most important properties defining malignancy. The adeno-virus E1A (Ad-E1A) gene has a dual effect as a proliferative gene and as a tumor-suppressor gene, decreasing tumor growth and the metastatic potential of malignant cells. In order to study genes related with the antimetastatic effect of Ad-E1A in human cells, we performed a microarray analysis using OncoChiptrade mark. In three independent experiments, NIH3T3, IMR90 and MDA MB 435 cells were infected with pLPC retroviruses carrying the adenovirus 12S E1A gene or the GFP gene. We analyzed cDNA expression by using the CNIO OncoChipTM, a cDNA microarray containing a total of 6386 genes represented by 7237 clones. uPA, uPAr, tPA, PAI-1 and PAI-2 were also studied at RNA and protein levels. Microarrays of cDNA expression, RT-PCR and Western blot performed in IMR90 E1A-expressing cells showed downregulation of uPA, uPAr, tPA, PAI-1 and upregulation of PAI-2. These results were confirmed in NIH3T3 and MDA MB 435 breast carcinoma cells, with PAI-2 upregulation by RT-PCR and Western blot. In addition, zymographic analysis demonstrated that E1A expression greatly reduced the gelatinase activity of the pro-MMP2 and -MMP9 proteins. We propose that adenovirus E1A may orchestrate the expression of most members of the urokinase-plasminogen activation system, downregulating potentially invasive genes and upregulating PAI-2, which is associated with a better prognosis in human tumors.