Extracellular matrix composition and interstitial pH modulate NHE1-mediated melanoma cell motility

Area of Science:

• Oncology
• Cell Biology
• Biochemistry

Background:

• The Na+/H+ exchanger 1 (NHE1) plays a crucial role in melanoma cell adhesion and migration.
• Understanding NHE1's role in melanoma invasion is vital for developing targeted therapies.

Purpose of the Study:

• To investigate the efficacy of inhibiting NHE1 using cariporide in suppressing mouse melanoma (B16V) cell invasion in vivo and in vitro.
• To analyze the impact of NHE1 inhibition on melanoma cell adhesion, migration, and metastasis.

Main Methods:

• Intravital microscopy in rats to observe B16V cell adhesion and migration in liver sinusoids.
• In vitro adhesion and invasion assays using basement membrane-like and dermis-like matrices.
• Time-lapse video microscopy to assess cell motility.
• Small-animal PET imaging in mice to track B16V metastasis.

Main Results:

• Cariporide treatment reduced B16V cell invasion by approximately 50% in vivo without affecting adhesion.
• In vitro, cariporide significantly decreased migratory speed and completely inhibited invasion of both matrices.
• While metastasis incidence was unchanged, cariporide-treated mice showed lung-directed metastasis compared to widespread metastasis in controls.
• B16V cells demonstrated greater invasion in dermis-like matrices than basement membrane-like matrices.

Conclusions:

• NHE1 activity is critical for melanoma cell invasion, particularly in dermis-like extracellular matrix (ECM) environments.
• Cariporide effectively inhibits melanoma cell motility and invasion, though its efficacy in metastasis may be influenced by ECM composition and lung microenvironment.
• The lungs represent a metastasis-prone site, potentially limiting cariporide's therapeutic impact due to specific ECM and pH characteristics.