Comparative analysis of the bioenergetics of human adenocarcinoma Caco-2 cell line and postoperative tissue samples from colorectal cancer patients

Abstract

The aim of this work was to explore the key bioenergetic properties for mitochondrial respiration in the widely-used Caco-2 cell line and in human colorectal cancer (HCC) postoperational tissue samples. Oxygraphy and metabolic control analysis (MCA) were applied to estimate the function of oxidative phosphorylation in cultured Caco-2 cells and HCC tissue samples. The mitochondria of Caco-2 cells and HCC tissues displayed larger functional activity of respiratory complex (C)II compared with CI, whereas in normal colon tissue an inverse pattern in the ratio of CI to CII activity was observed. MCA showed that the respiration in Caco-2 and HCC tissue cells is regulated by different parts of electron transport chain. In HCC tissues, this control is performed essentially at the level of respiratory chain complexes I-IV, whereas in Caco-2 cells at the level of CIV (cytochrome c oxidase) and the ATP synthasome. The differences we found in the regulation of respiratory chain activity and glycose index could represent an adaptive response to distinct growth conditions; this highlights the importance of proper validation of results obtained from in-vitro models before their extrapolation to the more complex in-vivo systems.

Mitochondrial Respiration in KRAS and BRAF Mutated Colorectal Tumors and Polyps

“…Premalignant polyps and arising adenocarcinomas are still regarded as highly glycolytic tumors of the Warburg phenotype [19][20][21]. Previous studies indicate that although polyps have higher inclination to aerobic glycolysis, the metastatic carcinomas maintain high rates of O 2 consumption (much more than adjacent normal tissues) and exhibit obvious signs of stimulated mitochondrial biogenesis [6,[22][23][24]. In this regard, we assume that upon malignant transformation, there is a selection of specific cell clones that have stimulated mitochondrial biogenesis and, as a result, have elevated aggressiveness.…”

Viability and mitochondrial bioenergetic functions in human colon cancer cells are not affected by treatment with peptides mtCPP1, UPF25, mtgCPP, and mtCPP1gHO

“…The cell pellet was suspended in medium-B [25] supplemented with 2 mg/mL fatty-acid free bovine serum albumin and 5 µM leupeptin (a protease inhibitor) and stored on ice. The viability of these cells was around 95% according to trypan blue (TB) exclusion test.…”

“…To evaluate the cytotoxic activity of four different CPPs against human epithelial colorectal adenocarcinoma cells (Caco-2) were incubated with a dose of 5µM for 24h. Human CRC cells compared with unaffected tissue cells have an increased energy demand, which is manifested in their increased glycolytic activity and rates of OXPHOS [9,25]. Colorectal adenocarcinoma maintains high rates of glucose consumption and has a higher tendency to aerobic glycolysis [9,32].…”

“…This phenomenon may be related to the elevated expression of some glucose transporters [33] and glycolytic enzymes [34,35], or predominantly, by the mitochondrial VDACbound HK-1 or 2, which use mitochondrially generated ATP to phosphorylate glucose in large amounts [5,9,10]. In this work, we evaluated Caco-2 cells as a model system expressing VDACassociated HK-2 similarly to human colorectal cancer [25]. Experiments were carried out to estimate the impact of CPPs on the inclination of Caco-2 cells to aerobic glycolysis (the Warburg behavior).…”

“…Our previous studies showed that CRC cells, unlike many other human cancers, have high rates of basal and ADP-stimulated respiration along with obvious signs of stimulated mitochondrial biogenesis [9,10]. Thus, controlling the mitochondrial respiration may be a new strategy for the treatment of CRC [25]. Moreover, it was reported that the intracellular level of ATP is a crucial factor determining chemoresistance in CRC [26].…”