Page 170 - SRPSKO DRUŠTVO ISTRAŽIVAČA RAKA

Serbian Association for Cancer Research SDIRSACR

SESSION 13

TUMOR METABOLISM

P83

Sodium bicarbonate–induced alkalization modulates tumor cell viability and metabolic activity in vitro

Alexey Bogdanov, Andrey Bogdanov, Vladimir Burdakov, Kseniya Mitusova, Vladimir Moiseenko

N.P. Napalkov St. Petersburg Clinical Scientific and Practical Center for Specialized Medical Care (Oncology), Saint Petersburg,
Russia

Keywords: alkalizing therapy, tumor cells, sodium bicarbonate

Background: Tumor cells display a hyperactive metabolism marked by aerobic glycolysis (the Warburg effect), leading
to excess lactate production and extracellular acidosis, which promotes invasion, metastasis, and extracellular matrix
remodeling – hallmarks of the acidic tumor microenvironment that enhance cancer cell survival and malignancy. This
study aimed to investigate the effects of alkalizing tumor cells in vitro using sodium bicarbonate (NaHCO3) as a pH-
modulating agent.
Materials and Methods: Mouse CT26 colon adenocarcinoma and patient-derived melanoma cells were cultured
at 37°C, 5% CO₂ in RPMI-1640 or DMEM/F12 medium supplemented with 10% fetal bovine serum, and 50 µg/mL
gentamicin. Alkalization was induced by supplementing the culture media with NaHCO3 solution, adjusted for baseline
bicarbonate concentrations in each medium. Medium pH was monitored via phenol red spectral changes, metabolites
were analyzed biochemically, and apoptosis (Annexin V-FITC/PI), lysosomal activity (Lyso Green), proliferation (Ki67), and
cell migration and monolayer recovery (scratch wound assay) were assessed according to manufacturer's instructions.
Results: Elevated NaHCO₃ concentrations significantly reduced cell proliferation and increased cytotoxicity. No further
increase in cell number was observed at NaHCO₃ concentrations exceeding 0.95 M. While NaHCO₃ supplementation
proportionally raised the initial extracellular pH, progressive acidification occurred over time due to ongoing cellular
metabolism and metabolite accumulation, despite regular medium changes. Concomitant decreases in glucose and
glutamine levels, along with increased lactate production, indicated sustained metabolic activity. At higher NaHCO₃
concentrations, glucose was completely depleted within 48 hours without medium renewal. Additionally, elevated
bicarbonate levels enhanced lysosomal activity, as detected by flow cytometry using Lyso Green, and delayed monolayer
wound healing in both CT26 and melanoma cells.
Conclusions: Alkalizing tumor cells with sodium bicarbonate may exert antitumor effects by disrupting metabolic
homeostasis and inducing programmed cell death. These findings suggest that modulating the acidic tumor
microenvironment through bicarbonate-based interventions could represent a promising adjunctive strategy in cancer
therapy.

Acknowledgments and funding: The study was funded by a grant from the Russian Science Foundation № 24-15-
00297, https://rscf.ru/en/project/24-15-00297/

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