CUX1 Enhances Pancreatic Cancer Formation by Synergizing with KRAS and Inducing MEK/ERK-Dependent Proliferation

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• The transcription factor CUT homeobox 1 (CUX1) has dual roles in cancer, acting as a tumor suppressor or promoter depending on the cancer type and specific isoform.
• Previous in vitro studies demonstrated CUX1's role in promoting tumor cell proliferation and apoptosis resistance in pancreatic cancer cell lines.
• However, in vivo evidence regarding CUX1's impact on pancreatic carcinogenesis, its isoform-specific functions, and downstream signaling pathways remained limited.

Purpose of the Study:

• To investigate the in vivo effects of different CUX1 isoforms on pancreatic carcinogenesis in the context of oncogenic KRAS.
• To elucidate the downstream signaling cascades activated by CUX1 during pancreatic cancer development.
• To identify the specific CUX1 isoform driving pancreatic cancer formation.

Main Methods:

• Crossbreeding of CUX1 isoform mouse models (p200 CUX1 and p110 CUX1) with KC mice (KrasLSL-G12D/+; Ptf1aCre/+), a genetic model for pancreatic intraepithelial neoplasia (PanIN).
• Histopathological analysis of pancreatic tissues to assess PanIN formation and invasive pancreatic ductal adenocarcinoma (PDAC) development.
• In vitro and in vivo assays to investigate CUX1-mediated signaling pathways, including MEK-ERK, ADAM17, EGFR, and MOS.

Main Results:

• Both KCCux1p200 and KCCux1p110 mice exhibited increased PanIN formation and PDAC development compared to KC mice.
• Tumor development was significantly accelerated in KCCux1p110 mice, with invasive PDAC forming within 4 weeks.
• CUX1 was found to enhance proliferation by activating MEK-ERK signaling through increased ADAM17 and subsequent EGFR activation.
• CUX1 also upregulated MOS, leading to KRAS-independent MEK-ERK activation.
• The p110 CUX1 isoform was identified as the primary driver of pancreatic cancer formation in the presence of mutant KRAS.

Conclusions:

• This study provides the first in vivo evidence for CUX1's critical role in pancreatic cancer development.
• The p110 CUX1 isoform is a major driver of pancreatic carcinogenesis, particularly in the context of mutant KRAS.
• CUX1-dependent signaling pathways, including MEK-ERK activation via ADAM17/EGFR and MOS, represent potential therapeutic targets for pancreatic cancer.