Acidic stress promotes a glioma stem cell phenotype

Area of Science:

• Oncology
• Cancer Biology
• Tumor Microenvironment

Background:

• Malignant gliomas exhibit cellular hierarchies with glioma stem cells (GSCs) at the apex.
• GSC location in specialized niches suggests tumor microenvironment regulation of the GSC phenotype.
• Hypoxia and its molecular responses are known regulators of GSC maintenance.

Purpose of the Study:

• To investigate the role of acidic conditions, independent of oxygen levels, in regulating GSC phenotype and tumor growth.
• To explore the molecular mechanisms, including hypoxia-inducible factors, by which acidity influences GSCs.
• To assess the therapeutic potential of modulating intratumoral pH.

Main Methods:

• In vitro experiments exposing GSCs to acidic conditions.
• Analysis of GSC marker expression, self-renewal capacity, and tumor growth.
• Investigation of the role of hypoxia-inducible factor 2α (HIF2α) and angiogenic factor expression.
• Assessment of the effects of pH elevation on GSC markers in vitro.

Main Results:

• Acidic conditions, independent of hypoxia, significantly promoted GSC marker expression, self-renewal, and tumor growth.
• Low pH augmented the expression of angiogenic factors via induction of HIF2α, a GSC-specific regulator.
• Elevating pH in vitro reverted the induction of HIF2α and other GSC markers by acidic stress.

Conclusions:

• Exposure to low pH promotes malignancy by inducing a cancer stem cell phenotype in gliomas.
• Modulating intratumoral pH represents a potential therapeutic strategy for targeting GSCs.
• Culturing cancer cells at physiologically relevant acidic pH may better preserve tumor heterogeneity for research.