It is known that Akt kinases 1, 2 and 3 have critical roles in regulating survival, metabolism and other cellular activities. However, their functions on migratory potential and metastasis development are less clear. GPC3 is a proteoglycan downregulated in breast tumors. We have previously shown that GPC3 reexpression inhibits metastatic capacity in vivo of the LM3 murine mammary adenocarcinoma cells. Moreover, this phenomenon was associated with a partial reversion of the epithelial-to-mesenchymal transition as shown in vitro. On the other hand, we have also determined that GPC3 modulates Akt signaling pathway in LM3 cells. The aim of this work was to investigate the role of Akt1 on the invasive/metastatic behavior of GPC3 reexpressing cells. First, we have confirmed that LM3-GPC3 cells present higher Akt1 levels than LM3-vector ones by western blot. To elucidate the function of this isoform, LM3-GPC3 clones were infected with viruses carrying a constitutively active variant of Akt1 (CA Akt1). Although there were no changes in the actin cytoskeleton organization, we could determine by a wound healing assay that LM3-GPC3-CA Akt1 cells were less migrant than their controls (Wound coverage: LM3-GPC3 control=50% vs. LM3-GPC3-CA Akt1=30%, p<0.05). To address an in vivo effect, different clones were injected s.c. into syngeneic female BALB/c mice. We found that these tumors did not differ in their growth rate, reaching a similar size at 30 days post inoculation (LM3-vector= 189±25, LM3-GPC3= 181±40, LM3-GPC3-CA Akt1= 200±51 mm3). No differences were found in either tumor incidence or in tumor latency. In order to study the experimental metastatic ability, all cell lines were i.v. inoculated. We observed that LM3-GPC3-CA Akt1 tumors developed fewer lung metastases than controls (Median [Range]: LM3-GPC3 control=9 [3-29] vs. LM3-GPC3 CA Akt1=0.5 [0-10], p<0.05). Moreover, the LM3-GPC3-CA Akt1 metastatic nodes were also of a smaller size (<0.5 mm). In sum, our results suggest that Akt1 expression and signaling could be mediating GPC3 inhibitory effect on the metastatic dissemination. The over-activation of this oncogene would exacerbate or heighten GPC3 effects, preventing the metastasis progression through the reduction of cell migration.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2231. doi:1538-7445.AM2012-2231

©2012 American Association for Cancer Research
2012