TGFβ engages MEK/ERK to differentially regulate benign and malignant pancreas cell function

Area of Science:

• Molecular Biology
• Cancer Research
• Cell Signaling

Background:

• Transforming growth factor beta (TGFβ) signaling exhibits dual roles in pancreatic cancer, acting anti-proliferatively in early stages but promoting progression in advanced cancers.
• Understanding the dysregulation of the TGFβ pathway is crucial for developing effective pancreatic cancer therapies.

Purpose of the Study:

• To investigate the role of ERK phosphorylation in TGFβ signaling during pancreatic carcinogenesis.
• To elucidate the differential functions of TGFβ and MEK/ERK pathways in benign, pre-neoplastic, and cancerous pancreatic cells.

Main Methods:

• Generation of mouse models with TGFβ receptor deficiencies.
• Analysis of ERK phosphorylation, pSMAD2, p21, and CDK2 levels in response to TGFβ.
• Inhibition of ERK phosphorylation to assess its impact on TGFβ-induced cellular responses, including EMT.

Main Results:

• TGFβ induced ERK phosphorylation in benign pancreatic duct cells, which was dependent on TGFBR1.
• ERK inhibition in duct cells reduced TGFβ-induced pSMAD2 and p21, prevented CDK2 downregulation, and blocked EMT.
• In neoplastic and cancer cells, ERK's role diverged, with pERK required for p21 upregulation and EMT but not pSMAD2 phosphorylation or CDK2 repression by TGFβ.

Conclusions:

• ERK acts as a key mediator in TGFβ signaling, initially facilitating cell cycle arrest but later antagonizing it during carcinogenesis.
• ERK remains critical for the pathological EMT-inducing effects of TGFβ signaling in pancreatic cancer.
• The TGFβ and MEK/ERK pathways exhibit a complex, stage-dependent interplay in pancreatic neoplasia.