Hello Priyansha Singh

It was Marroquin et al. (2007) who proposed a model of HepG2 cells to mitochondrial toxicants by replacing glucose with galactose in cell culture media. You may want to refer to his paper attached below for more information.

Article Circumventing the Crabtree Effect: Replacing Media Glucose w...

Not every cell line is amenable to culture in galactose. Therefore, for mitochondrial toxicity studies, HepG2 cells are used.

Let me explain further.

When you carry out in vitro anticancer studies on immortalized cancer cells in media containing high glucose, the mechanistic studies investigating the role of mitochondria in cancer cells cannot be studied due to the Crabtree effect. The Crabtree effect decreases oxidative phosphorylation in response to increasing glucose concentration and allows cancer and proliferating cells to adjust their energy metabolism depending on substrate availability. So, the mitochondria are not sufficiently active for energy homeostasis in cancer cells in high glucose-conditioned media.

By replacing glucose with galactose in cell culture media, HepG2 cells are forced to produce ATP by shifting from the cytosol to the mitochondria, consequently making HepG2 cells vulnerable to mitochondrial toxicity. When considering that mitochondria play an essential role in biomass synthesis, including fatty acids, amino acids, and nucleotides, which are required for the growth and proliferation of cancer cells, it becomes essential to investigate the interactions of anticancer drugs with possible regions or structures in mitochondria by using HepG2 cells as they are vulnerable to mitochondrial toxicity.

So, when HepG2 cells are forced to rely on mitochondrial oxidative phosphorylation rather than glycolysis by substituting galactose for glucose in the growth media, oxygen consumption doubles in galactose grown HepG2 cells and their susceptibility to canonical mitochondrial toxicants correspondingly increases. Similarly, toxicity of several drugs with known mitochondrial liabilities is more readily apparent in aerobically poised HepG2 cells compared to glucose-grown cells.

So, for mitochondrial toxicity studies using HepG2 cells, you have to replace glucose with galactose in the cell culture media.

Best.