Hepatocyte growth factor at S phase induces G2 delay through sustained ERK activation

Area of Science:

• Cell Biology
• Molecular Biology
• Cancer Research

Background:

• The precise impact of growth factors on cell cycle progression beyond the G1/S transition remains largely unclear.
• Understanding these mechanisms is crucial for comprehending cellular responses to growth signals and developing targeted therapies.

Purpose of the Study:

• To investigate the effects of hepatocyte growth factor (HGF) on cell cycle progression when administered during the S phase.
• To elucidate the specific signaling pathways involved in HGF-induced cell cycle modulation in HeLa cells.

Main Methods:

• HeLa cells were treated with HGF during the S phase.
• Cell cycle progression was analyzed using flow cytometry and mitotic index assessments.
• Protein degradation (cyclin A, cyclin B) and kinase activities (Cdk1/cyclin B, Cdk2/cyclin A) were monitored.
• Signaling pathway activation (ERK, p38MAPK, JNK) was assessed, along with the effects of MEK inhibitors (U0126, DN-MEK).

Main Results:

• HGF treatment during S phase induced a significant G2 cell cycle delay in HeLa cells.
• This delay correlated with delayed degradation of cyclin A and cyclin B, and sustained kinase activities of Cdk1/cyclin B and Cdk2/cyclin A.
• Sustained activation of the ERK pathway was observed, while p38MAPK and JNK remained unaffected.
• Inhibition of the MEK-ERK pathway partially reversed the HGF-induced G2 delay.

Conclusions:

• Hepatocyte growth factor (HGF) administration during the S phase triggers a G2 cell cycle delay in HeLa cells.
• The MEK-ERK signaling pathway plays a partial but significant role in mediating this HGF-induced G2 delay.
• These findings contribute to understanding growth factor signaling in cell cycle regulation and potential therapeutic interventions.