Effect of SLC5A8 Missense Variants on Its Tumor-Suppressive Function

Area of Science:

• Molecular Biology
• Cancer Research
• Genetics

Background:

• Solute Carrier Family-5 Member-8 (SLC5A8) is a plasma membrane transporter crucial for monocarboxylate transport.
• SLC5A8 exhibits tumor-suppressive properties in colorectal cancer (CRC), primarily through inhibiting histone deacetylases via specific metabolites.
• The impact of SLC5A8 genetic variants on its tumor-suppressive function remains largely uninvestigated.

Purpose of the Study:

• To investigate the effects of common SLC5A8 missense variants on transporter expression.
• To evaluate how these variants influence the tumor-suppressive function of SLC5A8 in CRC cells.
• To determine the functional consequences of SLC5A8 genetic alterations in cancer.

Main Methods:

• Identification of common SLC5A8 missense variations using the NCBI dbSNP database.
• Generation of CRC cell lines (HCT116, DLD-1) stably overexpressing wild-type SLC5A8 or its variants.
• Assessment of SLC5A8 expression via immunoblotting and evaluation of tumor-suppressive function using colony formation, wound healing, and invasion assays.

Main Results:

• Two common missense variants, Val193Ile (rs1709189) and Met490Ile (rs164365), were identified, forming two haplotypes.
• The Val193Ile variant and a haplotype containing both variants (H2) significantly reduced SLC5A8 expression.
• Reduced SLC5A8 expression correlated with increased proliferation, migration, and invasion of CRC cells.

Conclusions:

• Missense variants in SLC5A8 can significantly decrease its expression levels.
• The diminished SLC5A8 expression resulting from these variants impairs its critical tumor-suppressive functions.
• SLC5A8 genetic variations represent a potential factor influencing colorectal cancer progression.