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Pancreatic cancer cell proliferation is phosphatidylinositol 3-kinase dependent
R A Perugini1, T P McDade, F J Vittimberga
1Department of Surgery, University of Massachusetts Medical School, Worcester, MA 01655-0333, USA.
Background:
Genetic mutations found in pancreatic cancer (K-ras, p16, p53) lead to inappropriate cellular proliferation. Mitogens stimulate proliferation via the phosphatidylinositol 3-kinase (PI3K)- and/or the p44/42-mitogen-activated protein kinase [p44/42-MAPK or extracellular signal-regulated kinase (ERK)] signaling pathways. We examined whether inhibition of either PI3K or ERK could limit proliferation in human pancreatic cancer.
Methods:
Proliferation was stimulated in quiescent human pancreatic cancer cell lines (BxPC3 and Panc-1) by 10% fetal calf serum (FCS). In certain samples, PD98059 (an ERK inhibitor) or LY294002 (a PI3K inhibitor) was also added. AKT phosphorylation (indicating PI3K activity) and ERK phosphorylation (ERK activation) were determined by Western blot. Cell viability was determined by MTT assay. Cell cycle progression and apoptosis were determined by flow cytometry. A two-tailed t test was used for statistical analysis of the data (significance P < 0.05).
Results:
LY294002 inhibited the PI3K pathway without affecting ERK activation in response to serum. PD98059 inhibited the ERK pathway specifically. In both BxPC-3 and Panc-1 cell lines, LY294002 inhibited serum-induced proliferation. This was associated with G(1) cell cycle arrest and with an increase in the rate of apoptosis. PD98059 inhibited proliferation only in BxPC3 cells, and to a lesser degree than did LY294002.
Conclusions:
PI3K signaling appears to be necessary for G(1)-to-S phase progression and proliferation in pancreatic cancer cells. ERK plays a lesser role in mitogen-induced proliferation. Pharmacological inhibition of PI3K may decrease proliferation, increase apoptosis, and potentially confer therapeutic benefit in pancreatic cancer.
Insights
Inhibiting phosphatidylinositol 3-kinase (PI3K) signaling significantly reduced pancreatic cancer cell proliferation and increased apoptosis. Extracellular signal-regulated kinase (ERK) inhibition had a lesser effect, suggesting PI3K is crucial for pancreatic cancer growth.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Pancreatic cancer growth is driven by genetic mutations (K-ras, p16, p53) causing uncontrolled cellular proliferation.
- Mitogens stimulate proliferation through phosphatidylinositol 3-kinase (PI3K) and/or p44/42-mitogen-activated protein kinase (ERK) pathways.
- Investigating PI3K and ERK inhibition offers potential therapeutic strategies for pancreatic cancer.
Purpose of the Study:
- To determine if inhibiting PI3K or ERK signaling pathways can limit proliferation in human pancreatic cancer cells.
- To elucidate the specific roles of PI3K and ERK in driving pancreatic cancer cell growth.
Main Methods:
- Human pancreatic cancer cell lines (BxPC3, Panc-1) were treated with serum to stimulate proliferation.
- Specific inhibitors LY294002 (PI3K inhibitor) and PD98059 (ERK inhibitor) were used.
- Western blot, MTT assay, and flow cytometry assessed pathway activity, cell viability, cell cycle, and apoptosis.
Main Results:
- LY294002 effectively inhibited the PI3K pathway and serum-induced proliferation in both cell lines.
- PI3K inhibition led to G1 cell cycle arrest and increased apoptosis.
- PD98059 showed limited effect on proliferation, primarily in BxPC3 cells, indicating a lesser role for ERK.
Conclusions:
- PI3K signaling is essential for G1-to-S phase progression and proliferation in pancreatic cancer.
- Targeting PI3K could be a promising therapeutic strategy to reduce pancreatic cancer proliferation and induce apoptosis.
- ERK signaling plays a secondary role in mitogen-induced proliferation compared to PI3K.