Targeting Notch1 and IKKα Enhanced NF-κB Activation in CD133⁺ Skin Cancer Stem Cells

Area of Science:

• Oncology
• Cancer Stem Cell Biology
• Molecular Biology

Background:

• Cancer stem-like cells are crucial for tumor initiation in cutaneous squamous cell carcinoma (cSCC).
• The molecular pathways regulating these stem cells and their potential as therapeutic targets remain largely undefined.
• Identifying these pathways is critical for developing effective treatments against cSCC recurrence and metastasis.

Purpose of the Study:

• To isolate and characterize CD133+ cancer stem cells from primary cSCC specimens.
• To identify molecular alterations and signaling pathways, particularly NOTCH and NF-κB, that maintain the stemness of these cells.
• To evaluate the therapeutic potential of targeting identified pathways in cSCC.

Main Methods:

• Isolation of CD133+ cells from cSCC using multi-parameter flow cytometry.
• In vitro (spheroid/colony formation) and in vivo (tumorigenesis) assays to assess stem-like phenotypes.
• Gene expression profiling to identify differentially expressed genes and pathways.
• Pharmacologic and genetic targeting of NOTCH1, IKKα, RELA, and RELB to assess effects on NF-κB signaling and stem cell phenotypes.

Main Results:

• A highly enriched CD133+ cell population with enhanced stem-like properties was isolated.
• Gene expression analysis revealed significant enrichment of NOTCH, NF-κB, WNT, and other cancer-related pathways in CD133+ cells.
• Targeting NOTCH1 and IKK/NF-κB components (IKKα, RELA, RELB) effectively modulated NF-κB activity, reduced the CD133+ cell population, and diminished stemness phenotypes.
• Colocalization of CD133+ and IKKα expression was confirmed in cSCC specimens.

Conclusions:

• A novel link between NOTCH1, IKKα, and NF-κB pathway activation was identified as critical for maintaining CD133+ cSCC stem cell phenotypes.
• Targeting these pathways represents a promising therapeutic strategy for cSCC.
• Further investigation into modulators of these pathways could accelerate the development of treatments to prevent cSCC recurrence and metastasis.