Role of Akt In Inflammatory Breast Cancer

Date
2014-05
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University of Delaware
Abstract
Inflammatory Breast Cancer (IBC) is a rare and aggressive form of breast cancer with a rapid progression and lower survival rates than non-IBC types. Research aimed at understanding the role of various enzymes involved in controlling cell growth identified the serine/threonine kinase Akt as a major factor involved in cell growth and proliferation. Previous published studies have shown that Akt activation may be increased in IBC cell line SUM-149 relative to non-IBC cell line MDA-231. Building on these studies, it was hypothesized that Akt inhibition using Perifosine may be an effective strategy for reducing proliferation and invasion of breast cancer cells. MTT assay revealed that SUM-149 cells proliferated more than MDA-231 cells and Akt inhibition preferentially reduced IBC cell proliferation relative to non-IBC proliferation. Immunoblot analysis revealed that SUM-149 and MDA-231 cells expressed equal amounts of Akt 1 and Akt 3 isoforms but SUM-149 cells expressed lower amount of Akt 2 than MDA-231 cells. Attempts to further examine the role of individual Akt isoforms, especially Akt 3, on proliferation of IBC cells by siRNA knockdown of individual Akt isoforms to determine whether specific inhibition of an isoform reduces IBC cell proliferation proved to be unsuccessful. Combination therapies (Perifosine in combination with the PDGF inhibitor Crenolanib) were explored in order to limit drug toxicities through possible use of lower concentrations of each drug. Total Akt was immunoprecipitated in SUM-149 cells and activation was assessed using Akt-phospho-ser473. The experiment revealed that Perifosine treatment completely inhibited Akt activation while Crenolanib did not inhibit Akt activation. MTT assays conducted to assess proliferation revealed that Perifosine treatment alone was superior to inhibition of IBC cell proliferation compared to Crenolanib alone or in combination. Scratch wound assays were also conducted to assess role of Akt inhibition in migration in both IBC and non-IBC cells. In both cell lines, Perifosine did not appear to inhibit migration while Crenolanib, working through a different pathway, was successful in inhibiting migration. These results suggest that IBC cells utilize different pathways for proliferation and migration and Akt inhibition may be an effective strategy for inhibition of proliferation alone.
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