Analysis Of The Relative Expression Level Of PP1α/PP1γ And Their Tumorigenicity In Lung Cancer Cells

Protein phosphorylation and dephosphorylation existing in all kinds of cells are almost involved in every biological and pathological process and play an essential role in signal transduction. The two reverse processes are catalyzed by protein kinase and protein phosphatase respectively.The protein kinase is a huge and various gene family, while protein phosphatase only has few kinds. Protein phosphatase 1(PP1) is a heterodimer complex consisting of a catalytic subunit and a variable regulatory subunit, which is believed to regulate the specificity, activity and subcellular localization. It makes a lot of cell functions depend on PP1 possible.We have established H1299-pCI-neo,H1299-pCI-PP1α,H1299-pLKO.1 and H1299-pLKO.1-PP1αcell lines by liposome transfection using H1299 as the host cell. PP1αand PP1γexpression level in these cells was detected through Western Blot. The results revealed that when PP1αwas overexpressed, PP1γin H1299 decreased obviously. While PP1αwas knocked down, PPly soared.But the sum of PP1αand PP1γwas always almost the same. As for RT-PCR experiment, mRNA had the same situation, which indicated that the balance was regulated at the mRNA level.The proliferation experiment and nude mice experiment showed us that the cell cycle of those overexpressing PP1αwas slow and the tumor of those injected overexpressed PP1αcells was relatively small.Meantime, we found out that the expression pattern of Cyclin A/B/E resembled PP1α, going up and down when PP1αoverexpressed or knocked down.Above all,we could make such a conclusion, that is in H1299 cells,overexpressing PP1αcould lead to PP1r decrease while knocking down it, the amount of PP1r rises,but the sum of PP1αand PP1r is unchanged. Overexpressing PP1αcould slow down the cell cycle and inhibit the tumor growth.