Analyses Of Protein Expression Of Pi 3-Kinase/Akt Signaling In Response To Altered Expression Of Motor Protein Myo1c

In the previous work, a minimal region of recurrent deletion distal to the Tp53 gene was identified in BDII rat model for endometrial adenocarcinoma and the MYO1C gene was singled out as the tumor suppressor candidate in this region. Myo1c can bind to PIP2, the substrate of PI3-kinase, as well as to the mTOR complex, indicating a role for MYO1C in the PI3-kinase pathway. In this study, we assessed protein levels of 12 members of PI3-kinase/AKT signaling pathways in transient transfected HeLa cells expressing increasing amounts of MYO1C using Western blotting and densitometry analyses. Results revealed decreased protein levels of PTEN, AKT, and phosphorylated AKT, at both residues T308 and S473, and an increased expression of p110α protein in the cells transfected with the MYO1C gene expression constructs compared to the control cells transfected with empty plasmid. We next investigated potential effect of MYO1C protein depletion on serum-induced activation (phosphorylation) of AKT in the MCF10A cells that has de novo expression of MYO1C protein. Following serum stimulation, AKT was rapidly phosphorylated in its residue S473 (pAKTS473) in the cells transfected with MYO1C-siRNA, but with significantly lesser extent in the control cells. Overall, a negative correlation between the protein expression of MYO1C and AKT expression/activation was suggested, signifying a role for MYO1C as a negative regulator of PI3-kinsase/AKT signaling pathway. This is in agreement with the initial hypothesis of involvement of MYO1C in tumorigenesis pathways through its potential tumor suppressor activity. Further studies are required to fully understand the functional contribution of MYO1C to tumor development. Citation Format: Kittichate Visuttijai, Katarina Ejeskar, Afrouz Behboudi. Analyses of protein expression of PI 3-kinase/AKT signaling in response to altered expression of motor protein MYO1C. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2166. doi:10.1158/1538-7445.AM2015-2166