RUNX1/EGFR pathway contributes to STAT3 activation and tumor growth caused by hyperactivated mTORC1

Area of Science:

• Oncology
• Molecular Biology
• Cell Signaling

Background:

• Loss of function in tuberous sclerosis complex 1 or 2 (TSC1 or TSC2) leads to hyperactivation of the mammalian target of rapamycin complex 1 (mTORC1).
• Hyperactivated mTORC1 is implicated in tumor growth, but its precise mechanisms remain incompletely understood.

Purpose of the Study:

• To elucidate the downstream mechanisms by which hyperactivated mTORC1 drives tumor growth.
• To identify novel therapeutic targets for tumors associated with TSC and mTORC1 hyperactivation.

Main Methods:

• Analysis of Tsc1/Tsc2-null mouse embryonic fibroblasts, rat ELT3 cells, and human cancer cells.
• Investigated the role of epidermal growth factor receptor (EGFR) as a downstream target of mTORC1.
• Utilized gene knockdown and overexpression techniques to assess the impact of EGFR on cell proliferation and tumor growth.

Main Results:

• mTORC1 activation increases EGFR expression by upregulating runt-related transcriptional factor 1 (RUNX1).
• EGFR knockdown inhibits proliferation and tumor growth in Tsc-deficient cells; EGFR overexpression promotes proliferation in control cells.
• The mTOR signaling pathway positively correlates with EGFR expression in human cancers, and EGFR enhances cell growth via signal transducer and activator of transcription 3 (STAT3) activation.

Conclusions:

• The RUNX1/EGFR/STAT3 signaling pathway is a critical contributor to tumorigenesis driven by hyperactivated mTORC1.
• Targeting the RUNX1/EGFR/STAT3 pathway presents a promising therapeutic strategy for mTORC1-related tumors, especially those associated with TSC.