USE OF A NOVEL MIRNA PANEL FOR THE DEVELOPMENT OF SAFER AND MORE EFFECTIVE AKT INHIBITORS

Tufts Medical Center
posted on 06/07/2011

• request more info 
•   
•  LICENSE ONLINE

Tufts Medical Center Categories:
diagnostic:marker

Additional Keywords:
miRNA, miRNA-200a, miRNA-200b, miRNA-200c, Akt, Akt inhibitor, PKB, Akt isoform, Akt1, Akt2, Akt3

Invention Summary

Available from Tufts Medical Center

USE OF A NOVEL MIRNA PANEL FOR THE DEVELOPMENT OF SAFER AND MORE EFFECTIVE AKT INHIBITORS Lead Inventor: Dr. Philip Tsichlis TMC case# 420 Business opportunity: PI3K-Akt signaling pathway has been implicated in development and progression of human cancers. Three Akt isoforms (Akt1, Akt2 and Akt3) have been identified and numerous chemical inhibitors of this cascade are currently in development. Usually methods of Akt inhibition are based on regulation of total Akt signaling activity; consequently particular Akt inhibitors may significantly differ in their ability to target specific Akt isoforms. Dr. Philip Tsichlis of Tufts Medical Center and his collaborators have demonstrated that Akt1, Akt2 and Akt3 differ in their ability to transduce oncogenic signals and have both positive and negative effect on the development and progression of human cancers. These Tufts Medical Center researchers have further demonstrated that some processes, such as epithelial-mesenchymal transition -a characteristic feature of invasive cancers, are controlled by the ratio between Akt1 and Akt2 rather than by the overall activity of Akt pathway. Therefore, it’s critical for the development of safe and effective Akt inhibitors for the treatment of cancer that a particular Akt inhibitor strikes the right balance in its activity against different Akt isoforms which in turn requires a method to measure its effect on the Akt1/Akt2 ratio. Tufts Medical Center researchers have now developed such a method utilizing a panel of miRNAs differentially regulated by Akt1 and Akt2. Background: While the specific contribution of each of Akt isoform to oncogenesis is still being fully elucidated, Dr. Philip Tsichlis and his collaborators have used elegant in vitro and in vivo models to demonstrate that each Akt isoform has a different contribution to cancer initiation and progression. Downregulation of Akt2 in mouse mammary adenocarcinomas induced by transgenes encoding oncoprotein facilitates tumor formation, while ablation of Akt1 results in inhibition of tumor induction and growth. Interestingly, Akt1 deficiency promotes cell migration and epithelial mesenchymal transition accompanied by decrease in the expression of epithelial marker E-cadherin and upregulation of the expression of mesenchymal cell-specific protein Vimentin in mammary epithelial cells in vitro. In in vivo models, tumors, developing in Akt1-deficient mice, are more aggressive than in Akt2-deficient or wild-type mice. This data suggest that Akt1 deficiency inhibits growth of primary tumors but tumors appearing after the relapse may be much more invasive and aggressive Invention summary: Current invention provides a newly identified and specific miRNA panel that can be used to measure the Akt1/Akt2 isoform ratio, which information can be used to (i) modulate clinical treatment and (ii) develop better Akt inhibitors in the drug development process. The Akt1/Akt2 isoform ratio represents a surrogate method to discriminate between then beneficial and detrimental effects of isoform-specific Akt inhibition on tumor growth and metastasis. Using in vitro cell system and miRNA profiling, Tufts Medical Center scientists demonstrated that certain members of miR-200 family of miRNAs (e.g. miRNA-200a, -200b, -200c) targeting transcriptional repressors of E-cadherin Zeb1 and Zeb2, among others, are differentially regulated by Akt1 and Akt2 isoform activity. In particular, inhibition of Akt1, while leaving Act2 intact, results in (i) downregulation of miRNA-200a, -200b, -200c expression; (ii) decrease in the level of E-cadherin expression both on Mrna and protein level; (iii) facilitation of cell migration and epithelial-mesenchymal transition often associated with aggressive cancer phenotype and tumor invasiveness; and (iv) decrease in the sensitivity of tumor cells to hypoxia, making them more resistant to radiotherapy and chemotherapy. Conversely, overexpression of members of miRNA-200 family reverses the effects caused by Akt1 inhibition. This process is controlled by changes in Akt1/Akt2 ratio, rather than the total level of Akt signaling, since downregulation of both Akt1 and Akt2 isoforms attenuates the effect of Akt1 downregulation on Zeb1, Zeb2 and E-cadherin expression and cell migration. The important role of the Akt1/Akt2 isoform ratio in tumor progression was confirmed in mouse model of mammary adenocarcinomas: tumors arising in Akt1-deficient mice have low abundance of microRNAs of miR-200 family, are more aggressive, and have a greater metastatic potential than their Akt1-positive counterparts. Analysis of primary and metastatic human mammary adenocarcinoma clinical samples further confirmed that metastasis is associated with a decrease in the Akt1/Akt2 isoform ratio and downregulation of expression of miR-200 family of RNAs. Applications: This miRNA panel consisting of miRNA-200a, -200b, -200c provides a convenient method to analyze Akt1/Akt2 isoform ratio that can be used for the following applications: 1. Preclinical validation of new Akt inhibitors and optimization of current Akt-targeting therapies. The evidence demonstrates that safer and more efficacious Akt inhibitors will be the compounds that have the desired target specificity toward the Akt1 and Akt2 isoforms, resulting in a safe Akt1/Akt2 isoform ratio. The present miRNA-200a, -200b, -200c screening panel provides exactly such a method to determine whether a particular Akt inhibitor results in a safe Akt1/Akt2 isoform ratio. 2. Diagnostic tool for analysis of biological parameters of tumors such as metastatic potential and invasiveness The analysis of Akt1/Akt2 isoform ratio in patients, as measured by the difference in the expression of members of miR-200 family compared to normal control, can help physicians to analyze the metastatic potential of an existing tumor and assist to design an effective treatment protocol. Inventors: Lead inventor is Dr. Philip Tsichlis of Tufts Medical Center. Dr. Tsichlis’ laboratory has a long history in cancer research. Achievements relevant to the current invention include the discovery of the Akt kinase (Science 254: 274-277, 1991), the demonstration that Akt is a target of the PI-3 Kinase (Cell 81: 727-736, 1995), the demonstration that the oncogenic potentials of the three Akt isoforms differ dramatically (Cancer Res 67: 167-177, 2007; J Cell Physiol. 217: 468-77, 2008) and the development of elegant cell system to demonstrate that invasiveness, metastasis and stemness of cancer cells depend more on the balance between Akt1 and Akt2 rather than the overall Akt activity (Science Signaling Vol 2 Issue 92, 2009)