title: Dynamics of GFP-Fusion p110α and p110β Isoforms of PI3K Signaling Pathway in Normal and Cancer Cells.
abstract: Cancer therapeutics is a hot subject and PI3K class 1A isoforms (p110α and p110β) are pursued as major targets. Genetic analysis, biochemical approaches, and structural studies have demonstrated crucial roles for these isoforms in several physiological processes. p110α is critical for insulin signaling, whereas p110β is essential for the growth and differs from p110α in many ways. Here, we have generated GFP-fusion clones of wildtype and mutant version of p110α and p110β and expressed them in HEK293 and cancer cells to examine their subcellular localization and their impact on downstream signaling. In HEK293 cells, p110β GFP-fusion protein is translocated into the nucleus, whereas p110α-GFP stays exclusively in the cytoplasm. This study demonstrates that p110α and p110β oncogenecity, kinase activity, and interaction with p85 regulatory subunit does not have any impact on their subcellular localization. PI3K pathway specific inhibitor, LY294002, abrogated PI3K signaling by reducing pAkt levels, however, the subcellular localization of p110α and p110β remained unchanged. Furthermore, we analyzed the expression of recombinant p110α and p110β in a panel of human cancer cells and observed remarkable differences in their expression levels. The differential expression of recombinant p110α and p110β was observed to be mainly regulated by the endogenous levels of pAkt. Unlike in HEK293, p110α showed nuclear localization in cancer cells in a similar fashion to p110β. Moreover, we observed the PI3K signaling activities in low pAkt expressing cells are mediated by PDK1 and S6K proteins. Finally, p110α and p110β were seen to play an essential role in promoting the cell cycle progression in MCF-7 and HCT-116 cells. J. Cell. Biochem. 117: 2864-2874, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Academy of Scientific and Innovative Research, New Delhi, India.|Division of Cancer Pharmacology, CSIR-Indian Institute of Integrative Medicine, Jammu, Jammu and Kashmir, India.
authors.forename: Paramjeet
authors.initials: P
authors.lastname: Singh
authors.affiliation: Academy of Scientific and Innovative Research, New Delhi, India.|Division of Cancer Pharmacology, CSIR-Indian Institute of Integrative Medicine, Jammu, Jammu and Kashmir, India.
authors.forename: Mohd Saleem
authors.initials: MS
authors.lastname: Dar
authors.affiliation: Academy of Scientific and Innovative Research, New Delhi, India.|Division of Cancer Pharmacology, CSIR-Indian Institute of Integrative Medicine, Jammu, Jammu and Kashmir, India.
authors.forename: Gurjinder
authors.initials: G
authors.lastname: Singh
authors.affiliation: Academy of Scientific and Innovative Research, New Delhi, India.|Division of Cancer Pharmacology, CSIR-Indian Institute of Integrative Medicine, Jammu, Jammu and Kashmir, India.
authors.forename: Gayatri
authors.initials: G
authors.lastname: Jamwal
authors.affiliation: Academy of Scientific and Innovative Research, New Delhi, India.|Division of Cancer Pharmacology, CSIR-Indian Institute of Integrative Medicine, Jammu, Jammu and Kashmir, India.
authors.forename: Parduman Raj
authors.initials: PR
authors.lastname: Sharma
authors.affiliation: Academy of Scientific and Innovative Research, New Delhi, India.|Division of Neuropharmacology, CSIR-Indian Institute of Integrative Medicine, Srinagar, Jammu and Kashmir, India.
authors.forename: Muzamil
authors.initials: M
authors.lastname: Ahmad
authors.affiliation: Academy of Scientific and Innovative Research, New Delhi, India. jamal@iiim.ac.in.|Division of Cancer Pharmacology, CSIR-Indian Institute of Integrative Medicine, Jammu, Jammu and Kashmir, India. jamal@iiim.ac.in.
authors.forename: Mohd Jamal
authors.initials: MJ
authors.lastname: Dar
mesh_terms: D017209:Apoptosis; D015153:Blotting, Western; D002453:Cell Cycle; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D058543:Class Ia Phosphatidylinositol 3-Kinase / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D058543:Class Ia Phosphatidylinositol 3-Kinase
keywords: CANCER CELL LINES; CANCER THERAPEUTICS; CELL CYCLE ANALYSIS; CELLULAR SIGNALING; NUCLEAR LOCALIZATION; PI3K SIGNALING; pAkt