Cellular Adaptation Takes Advantage of Atavistic Regression Programs during Carcinogenesis

Abstract

Adaptation of cancer cells to extreme microenvironmental conditions (i.e., hypoxia, high acidity, and reduced nutrient availability) contributes to cancer resilience. Furthermore, neoplastic transformation can be envisioned as an extreme adaptive response to tissue damage or chronic injury. The recent Systemic-Evolutionary Theory of the Origin of Cancer (SETOC) hypothesizes that cancer cells "revert" to "primitive" characteristics either ontogenically (embryo-like) or phylogenetically (single-celled organisms). This regression may confer robustness and maintain the disordered state of the tissue, which is a hallmark of malignancy. Changes in cancer cell metabolism during adaptation may also be the consequence of altered microenvironmental conditions, often resulting in a shift toward lactic acid fermentation. However, the mechanisms underlying the robust adaptive capacity of cancer cells remain largely unknown. In recent years, cancer cells' metabolic flexibility has received increasing attention among researchers. Here, we focus on how changes in the microenvironment can affect cancer cell energy production and drug sensitivity. Indeed, changes in the cellular microenvironment may lead to a "shift" toward "atavistic" biologic features, such as the switch from oxidative phosphorylation (OXPHOS) to lactic acid fermentation, which can also sustain drug resistance. Finally, we point out new integrative metabolism-based pharmacological approaches and potential biomarkers for early detection.

Keywords: cancer drug resistance; tumor adaptation; tumor biology; tumor metabolism.

Figure 1

Schematic representation of evolutionary rewiring from prokaryotes to yeast to multicellular metazoans resulting in a phenotypic shift from undifferentiated, proliferative, and fermentative conditions to differentiated, quiescent, OXPHOS conditions. See the text for details. The figures were created with BioRender.

Figure 2

Schematic summary of the concept of carcinogenesis as an “atavistic regression” towards a pre-multicellular nucleated stage driven by chronic environmental stress. See the text for details. The figures were created with BioRender.

Figure 3

Schematic representation of the links between microenvironmental stress, metabolism, tumorigenesis, and drug resistance. See the text for details. The figures were created with BioRender.