Date

2022-8

Author

Hüsnügil, Hepşen Hazal

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Limited availability of nutrients to cancer cells can result in metabolic rewiring, manifesting in the activation of processes such as autophagy for survival. Our study shows for the first time that Caco-2 cells incubated in a nutrient-restriction (NR) medium of low glucose, glutamine and serum for 48h were viable but less proliferative, demonstrated robust autophagy induction and lower sensitivity to 5- Fluorouracil. However, the cargo protein p62 was not degraded efficiently, suggesting a slower autophagic flux. Perturbation of lysosomal acidification with Bafilomycin A1 (Baf) revealed the strong activation of partial epithelial to mesenchymal transition (EMT) with changes in gene expression and cellular morphology in NR cells. Different from these observations, post-confluent Caco-2 cells that were spontaneously differentiated, showed autophagy induction with functional autophagic flux and more epithelial characteristics. Culture of Caco-2 cells as 3D spheroids revealed that with NR, the spheroids were loosely formed while addition of Baf led to a complete loss of spheroid formation with loss of cell-cell adhesion. Our data with early- and late-stage autophagy inhibitors suggest that rather than autophagy induction itself, the slower autophagic flux, perhaps via p62 accumulation, could be implicated in the development of partial EMT and lower drug sensitivity in NR Caco-2 cells. Overall, our data suggest that low availability of nutrients may lead to the activation of a partial EMT program, particularly if the lysosomes are less acidic.

Subject Keywords

Colorectal Cancer, Nutrient Restriction, Autophagy, Lysosomal Alkalinization, Partial EMT

URI

https://hdl.handle.net/11511/99502

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Graduate School of Natural and Applied Sciences, Thesis