2025 Volume 53 Issue 1 Article ID: 53-1-2
Nutrients are needed for all organisms including cancer. Competition over nutrients is crucial for cancer cells being surrounded by normal cells, especially when they spread from the primary site. As noted by Otto Warburg, cancer displays metabolic flexibility in harsh microenvironments where nutrient availability is limited [1]. Despite numerous efforts to understand this flexibility [2], little attention has been paid to the possibility that cancer cells might utilize substrates that are unusable for normal cells as alternative nutrients [3]. L-glucose was thought to be non-existent in terrestrial surface. Even when administered, mammals take it up only minimally. Furthermore, even if it were taken up into cells, it could not be metabolized. Thus, L-glucose was considered as an unusable sugar [4]. In 2010, researchers found that spheroid-forming, cancer stem-like tumor cells, which expressed features indicative of high-grade malignancy, took up fluorescent dye-tagged analogue of not only D-glucose but also L-glucose [5, 6]. Almost at the same time, a bacterial species that metabolized L-glucose to pyruvate was found [7]. Similar bacteria appear to spread across phyla. Recent reports demonstrated bacterial residents in cancer cells of patients [8, 9]. These stories progress in tandem and have yet to link up. Our knowledge regarding glucose uptake and metabolism is still insufficient, particularly when energy is highly demanded as in tumorigenesis [3]. The least available sugar L-glucose provides a unique suggestion towards understanding of survival tactics used by malignant neoplasms that seek nutrients to proliferate.
