Members Members Residents Residents Corner
Join Today Renew Your Membership Make A Donation
2001 Abstract: 1786 Hypoosmotic Stress Stimulates Growth in HepG2 Cells Via PKB-Dependent Activation of AP-1

2001 Digestive Disease Week

# 1786 Hypoosmotic Stress Stimulates Growth in HepG2 Cells Via PKB-Dependent Activation of AP-1
Robin D. Kim, Timothy P. Roth, Chad E. Darling, Rocco Ricciardi, Bradley K Schaffer, Ravi S. Chari, Worcester, MA

Swelling by hypoosmotic stress activates PI-3-K, but its impact on the downstream signal PKB or cell growth is unknown. Although AP-1 activation is in part PI-3-K-dependent, its response to hypoosmotic stress is also undefined. We hypothesized that cell swelling modulates proliferation in HepG2 cells via PKB-dependent activation of AP-1.

Methods: HepG2 incubated for 1 hr with/out 50 mM LY294002 (LY), a PI-3-K inhibitor, were exposed for up to 30 min to hypoosmotic medium (200mOsm/L) to induce swelling. TNF-a (1.4 nM) or normoosmotic medium served as positive and negative controls, respectively. Western blots measured cytoplasmic phospho- and total PKB. EMSA measured nuclear AP-1. Methylene blue assays measured cell proliferation at 24, 48 and 72 hrs after pulse exposure to hypoosmotic stress. T test and ANOVA verified statistical significance. All experiments were performed in triplicate.

Results: [1] Hypoosmotic stress phosphorylated PKB (P-PKB) by 10 min, and this effect was inhibited by LY. [2] Hypooosmotic stress translocated AP-1 by 30 min, and this effect was inhibited by LY (Fig 1). [3] Hypoosmotic stress potentiated growth by 72 hrs as compared to both control and LY-inhibited cells (n=4 per group, p=0.009# and p=0.004*, respectively; p<0.001, ANOVA).

Conclusion: In HepG2 cells, hypoosmotic stress-induced swelling acts as a proliferative signal which is mediated by the PKB-dependent activation of AP-1. These data delineate a possible mechanism linking cell volume change to growth in human liver cancer.

Society for Surgery of the Alimentary Tract

Facebook Twitter YouTube

Email AAPS Email AAPS
500 Cummings Center, Suite 4400, Beverly, MA 01915 500 Cummings Center
Suite 4400
Beverly, MA 01915
+1 978-927-8330 +1 978-927-8330
+1 978-524-0498 +1 978-524-0498
Annual Meeting
Make a Pledge
Event Calendar