3716

The progression of cancer is a multi-step process and many signaling pathways are involved. The PI3K/Akt signaling pathway which regulates translational control, cell growth and proliferation has been reported as being overexpressed in breast tumors. The MCF10A cell line series is a model for Proliferative Breast Disease, and includes the non-tumorigenic human breast epithelial MCF10A cells, the T24 Ha-Ras transformed MCF10AT cells with minimal tumorigenic risk, and the MCF10AT-G3B cells, which result from sequential passage of 10AT cells and exhibit increased tumorigenic risk when implanted s.c in nude mice. Expression of the PI3K family (PI3KCA, CB and CD), the Akt/PKB family (Akt1, Akt2 and Akt3) and the ribosomal p70S6K mRNA levels in the MCF10A cell line series cultured on plastic and Matrigel was examined, using Real-Time PCR analysis to assess the mRNA levels of the individual family members and the role of the substrata on gene expression. PCR cycle threshold values were obtained, and mRNA levels were determined with GAPDH normalization. For cells plated on plastic, no significant change in PI3KCA, CB or CD mRNA levels was monitored across the three cell lines. In contrast, Akt2 was 10-fold lower in 10AT relative to 10A cells, whereas Akt1 was 5-fold lower in 3B cells relative to 10A cells. For cells plated on Matrigel, PI3KCA, CB and CD mRNA levels in 10A and 10AT cells were not significantly different, whereas PI3KCD was 3.7-fold lower in 3B cells relative to 10A cells. Akt1 and Akt2 mRNA levels were not significantly changed across the three cell lines, whereas Akt3 was decreased by 2.2-fold in 3B cells, relative to 10A cells. Comparison of PI3K, Akt family members and ribosomal p70S6K mRNA levels for cells cultured on Matrigel versus plastic revealed that Matrigel generally decreased the expression of PI3KCA, CB and CD in 3B cells, whereas Akt1 and Akt2 were increased in 10AT cells. Ribosomal p70S6K was slightly increased in 10AT cells on Matrigel. These data show that PI3K and Akt family members are differentially expressed in the MCF10A cell lines and suggest that the substrata may alter the expression of kinases critical to cell growth and proliferation. Supported by NIH grant ES 10595 and EHS Center Grant P30 ES06639.

[Proc Amer Assoc Cancer Res, Volume 46, 2005]