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Stromal cell-derived factor 1α mediates resistance to mTOR-directed therapy in pancreatic cancer

Colin D Weekes1, Dongweon Song, John Arcaroli

  • 1University of Colorado Cancer Center, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA. colin.weekes@ucdenver.edu

Neoplasia (New York, N.Y.)
|September 7, 2012
PubMed
Abstract

Insights

Stromal cell-derived factor 1α (SDF-1α)-CXCR4 signaling promotes resistance to mTOR-targeted therapy in pancreatic cancer. Combining CXCR4 and mTOR inhibitors overcomes this resistance by inhibiting key signaling pathways and tumor growth.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cancer Therapeutics

Background:

  • Pancreatic cancer therapy faces challenges in translating preclinical findings into clinical success, particularly with mTOR-targeted agents.
  • The tumor microenvironment is increasingly recognized as a critical factor influencing therapeutic response and resistance.

Purpose of the Study:

  • To investigate the role of Stromal cell-derived factor 1α (SDF-1α)-CXCR4 signaling as a microenvironmental factor contributing to resistance against mTOR-targeted therapy in pancreatic cancer.
  • To explore the potential of combined therapeutic strategies targeting CXCR4 and mTOR to overcome this resistance.

Main Methods:

  • Utilized primary pancreas explant xenografts and in vitro experiments to analyze SDF-1α-CXCR4 regulation of the mTOR pathway.
  • Pharmacodynamic analyses assessed intratumoral gene and protein expression of mTOR pathway effectors (cyclin D1, c-Myc, VEGF).
  • Evaluated combinatorial effects of CXCR4, EGFR, and mTOR inhibition in temsirolimus-resistant and -sensitive models.

Main Results:

  • Elevated intratumoral SDF-1α expression correlated with temsirolimus resistance.
  • SDF-1α stimulation induced CXCR4-mediated, PI3-kinase-dependent S6-RP phosphorylation, conferring temsirolimus resistance.
  • Combined inhibition of CXCR4 (AMD3465) and mTOR (temsirolimus) effectively inhibited tumor growth and overcame resistance.
  • CXCR4 signaling promoted intratumoral EGFR expression and increased VEGF, contributing to resistance.
  • Combined AMD3465, temsirolimus, and erlotinib (EGFR inhibitor) achieved significant tumor growth inhibition.

Conclusions:

  • SDF-1α-CXCR4 signaling is a key microenvironmental mechanism driving resistance to mTOR-targeted therapy in pancreatic cancer.
  • This signaling pathway promotes resistance through mechanisms including EGFR recruitment and angiogenesis.
  • Targeting the SDF-1α-CXCR4 axis in combination with mTOR inhibitors offers a promising strategy to enhance pancreatic cancer treatment efficacy.

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