Activation of Akt1 accelerates carcinogen-induced tumorigenesis in mammary gland of virgin and post-lactating transgenic mice.

BACKGROUND: Data from in vivo and in vitro studies suggest that activation of Akt regulates cell survival signaling and plays a key role in tumorigenesis. Hence, transgenic mice were created to explore the oncogenic role of Akt1 in the development of mammary tumors. METHODS: The transgenic mice were generated by expressing myristoylated-Akt1 (myr-Akt1) under the control of the MMTV-LTR promoter. The carcinogen 7, 12 dimethyl-1,2-benzanthracene (DMBA) was used to induce tumor formation. RESULTS: The MMTV driven myr-Akt1 transgene expression was detected primarily in the mammary glands, uterus, and ovaries. The expression level increased significantly in lactating mice, suggesting that the response was hormone dependent. The total Akt expression level in the mammary gland was also higher in the lactating mice. Interestingly, the expression of MMTVmyr-Akt1 in the ovaries of the transgenic mice caused significant increase in circulating estrogen levels, even at the post-lactation stage. Expression of myr-Akt1 in mammary glands alone did not increase the frequency of tumor formation. However, there was an increased susceptibility of forming mammary tumors induced by DMBA in the transgenic mice, especially in mice post-lactation. Within 34 weeks, DMBA induced mammary tumors in 42.9% of transgenic mice post-lactation, but not in wild-type mice post-lactation. The myr-Akt1 mammary tumors induced by DMBA had increased phosphorylated-Akt1 and showed strong expression of estrogen receptor (ERα) and epidermal growth factor receptor (EGFR). In addition, Cyclin D1 was more frequently up-regulated in mammary tumors from transgenic mice compared to tumors from wild-type mice. Overexpression of Cyclin D1, however, was not completely dependent on activated Akt1. Interestingly, mammary tumors that had metastasized to secondary sites had increased expression of Twist and Slug, but low expression of Cyclin D1. CONCLUSIONS: In summary, the MMTVmyr-Akt1 transgenic mouse model could be useful to study mechanisms of ER-positive breast tumor development.

Identification of Novel Biomarkers for Metastatic Colorectal Cancer Using Angiogenesis-Antibody Array and Intracellular Signaling Array.

Colorectal cancer (CRC) is one of the three leading causes for cancer mortality. CRC kills over 600,000 people annually worldwide. The most common cause of death from CRC is the metastasis to distant organs. However, biomarkers for CRC metastasis remain ill-defined. We compared primary and metastatic CRC cell lines for their angiogenesis-protein profiles and intracellular signaling profiles to identify novel biomarkers for CRC metastasis. To this end, we used primary and metastatic CRC cell lines as a model system and normal human colon cell line as a control. The angiogenesis profiles two isogenic CRC cell lines, SW480 and SW620, and HT-29 and T84 revealed that VEGF was upregulated in both SW620 and T84 whereas coagulation factor III, IGFBP-3, DPP IV, PDGF AA/AB, endothelin I and CXCL16 were downregulated specifically in metastatic cell lines. Furthermore, we found that TIMP-1, amphiregulin, endostatin, angiogenin were upregulated in SW620 whereas downregulated in T84. Angiogenin was downregulated in T84 and GM-CSF was also downregulated in SW620. To induce CRC cell metastasis, we treated cells with pro-inflammatory cytokine IL-6. Upon IL-6 treatment, epithelial-mesenchymal transition was induced in CRC cells. When DLD-1 and HT-29 cells were treated with IL-6; Akt, STAT3, AMPKα and Bad phosphorylation levels were increased. Interestingly, SW620 showed the same signal activation pattern with IL-6 treatment of HT-29 and DLD-1. Our data suggest that Akt, STAT3, AMPKα and Bad activation can be biomarkers for metastatic colorectal cancer. IL-6 treatment specifically reduced phosphorylation levels of EGFR, HER2 receptor, Insulin R and IGF-1R in receptor tyrosine kinase array study with HT-29. Taken together, we have identified novel biomarkers for metastatic CRC through the angiogenesis-antibody array and intracellular signaling array studies. Present study suggests that those novel biomarkers can be used as CRC prognosis biomarkers, and as potential targets for the metastatic CRC therapy.

Expression of FOXO1 is associated with GATA3 and Annexin-1 and predicts disease-free survival in breast cancer.

PURPOSE: To determine the prognostic value of FOXO1, GATA3 and Annexin-1 expression in breast cancer. METHODS: Tissue microarray and individual paraffin tissue slides from 131 patients were used for the study. The association of FOXO1, GATA3 and Annexin-1 expression with clinicopathological features of breast cancer and disease outcome was examined in retrospective samples. Kaplan-Meier survival curves and Cox regression with multivariate analysis were used for assessing the relative risk (RR) and disease-free survival (DFS). The expression of FOXO1, GATA3 and Annexin-1 were determined by immunohistochemistry and the association among the three proteins was analyzed by Logistic regression analysis. RESULTS: The nuclear expression of FOXO1 was observed in most of the normal breast tissues and 51.3% of the malignant breast tissues. GATA3 and Annexin-1 were expressed at 73% and 24.6% respectively in breast cancer tissues. The expression of FOXO1, GATA3 and Annexin-1 were all inversely correlated with lymph node-positive tumors. Both FOXO1 and Annexin-1 expression were also inversely associated with HER2-overexpressing tumors. FOXO1 expression was significantly associated with both GATA3 and Annexin-1 expression. In addition, Multivariate analyses confirm that only FOXO1 levels independently predict DFS. CONCLUSION: FOXO1 expression in breast cancer is regulated by the PI3K/Akt pathway. The expression of FOXO1 is also associated with GATA3 and/or Annexin-1. Restoring or targeting FOXO1 to the cell nucleus in breast cancer tissues may improve response to therapy and disease outcome. Further clinical studies are warranted to test this hypothesis.