Doxorubicin–transferrin conjugate alters mitochondrial homeostasis and energy metabolism in human breast cancer cells

Doxorubicin (DOX) is considered one of the most powerful chemotherapeutic agents but its clinical use has several limitations, including cardiomyopathy and cellular resistance to the drug. By using transferrin (Tf) as a drug carrier, however, the adverse effects of doxorubicin as well as drug resistance can be reduced. The main objective of this study was to determine the exact nature and extent to which mitochondrial function is influenced by DOX–Tf conjugate treatment, specifically in human breast adenocarcinoma cells. We assessed the potential of DOX–Tf conjugate as a drug delivery system, monitoring its cytotoxicity using the MTT assay and ATP measurements. Moreover, we measured the alterations of mitochondrial function and oxidative stress markers. The effect of DOX–Tf was the most pronounced in MDA-MB-231, triple-negative breast cancer cells, whereas non-cancer endothelial HUVEC-ST cells were more resistant to DOX–Tf conjugate than to free DOX treatment. A different sensitivity of two investigate breast cancer cell lines corresponded to the functionality of their cellular antioxidant systems and expression of estrogen receptors. Our data also revealed that conjugate treatment mediated free radical generation and altered the mitochondrial bioenergetics in breast cancer cells.This work was supported in part by Grant No. B1511000001026.02 of the University of Lodz, Poland

More Than Meets the Eye Regarding Cancer Metabolism

In spite of the continuous improvement in our knowledge of the nature of cancer, the causes of its formation and the development of new treatment methods, our knowledge is still incomplete. A key issue is the difference in metabolism between normal and cancer cells. The features that distinguish cancer cells from normal cells are the increased proliferation and abnormal differentiation and maturation of these cells, which are due to regulatory changes in the emerging tumour. Normal cells use oxidative phosphorylation (OXPHOS) in the mitochondrion as a major source of energy during division. During OXPHOS, there are 36 ATP molecules produced from one molecule of glucose, in contrast to glycolysis which provides an ATP supply of only two molecules. Although aerobic glucose metabolism is more efficient, metabolism based on intensive glycolysis provides intermediate metabolites necessary for the synthesis of nucleic acids, proteins and lipids, which are in constant high demand due to the intense cell division in cancer. This is the main reason why the cancer cell does not “give up” on glycolysis despite the high demand for energy in the form of ATP. One of the evolving trends in the development of anti-cancer therapies is to exploit differences in the metabolism of normal cells and cancer cells. Currently constructed therapies, based on cell metabolism, focus on the attempt to reprogram the metabolic pathways of the cell in such a manner that it becomes possible to stop unrestrained proliferation

Diverse Action of Selected Statins on Skeletal Muscle Cells—An Attempt to Explain the Protective Effect of Geranylgeraniol (GGOH) in Statin-Associated Myopathy (SAM)

The present study is centered on molecular mechanisms of the cytoprotective effect of geranylgeraniol (GGOH) in skeletal muscle harmed by statin-associated myopathy (SAM). GGOH via autophagy induction was purportedly assumed to prevent skeletal muscle viability impaired by statins, atorvastatin (ATR) or simvastatin (SIM). The C2C12 cell line was used as the ‘in vitro’ model of muscle cells at different stages of muscle formation, and the effect of ATR or SIM on the cell viability, protein expression and mitochondrial respiration were tested. Autophagy seems to be important for the differentiation of muscle cells; however, it did not participate in the observed GGOH cytoprotective effects. We showed that ATR- and SIM-dependent loss in cell viability was reversed by GGOH co-treatment, although GGOH did not reverse the ATR-induced drop in the cytochrome c oxidase protein expression level. It has been unambiguously revealed that the mitochondria of C2C12 cells are not sensitive to SIM, although ATR effectively inhibits mitochondrial respiration. GGOH restored proper mitochondria functioning. Apoptosis might, to some extent, explain the lower viability of statin-treated myotubes as the pan-caspase inhibitor, N-Benzyloxycarbonyl-Val-Ala-Asp(O-Me) fluoromethyl ketone (Z-VAD-FMK), partly reversed ATR- or SIM-induced cytotoxic effects; however, it does not do so in conjunction with caspase-3. It appears that the calpain inhibitor, N-Acetyl-L-leucyl-L-leucyl-L-norleucinal (ALLM), restored the viability that was reduced by ATR and SIM (p < 0.001). GGOH prevents SAM, in part, as a consequence of a caspase-3 independent pathway, probably by calpain system inactivation

Hexokinase 2 inhibition and biological effects of BNBZ and its derivatives : the influence of the number and arrangement of hydroxyl groups

Hexokinase 2 (HK2), an enzyme of the sugar kinase family, plays a dual role in glucose metabolism and mediating cancer cell apoptosis, making it an attractive target for cancer therapy. While positive HK2 expression usually promotes cancer cells survival, silencing or inhibiting this enzyme has been found to improve the effectiveness of anti-cancer drugs and even result in cancer cell death. Previously, benitrobenrazide (BNBZ) was characterized as a potent HK2 inhibitor with good anti-cancer activity in mice, but the effect of its trihydroxy moiety (pyrogallol-like) on inhibitory activity and some cellular functions has not been fully understood. Therefore, the main goal of this study was to obtain the parent BNBZ (2a) and its three dihydroxy derivatives 2b–2d and to conduct additional physicochemical and biological investigations. The research hypothesis assumed that the HK2 inhibitory activity of the tested compounds depends on the number and location of hydroxyl groups in their chemical structure. Among many studies, the binding affinity to HK2 was determined and two human liver cancer cell lines, HepG2 and HUH7, were used and exposed to chemicals at various times: 24 h, 48 h and 72 h. The study showed that the modifications to the structures of the new BNBZ derivatives led to significant changes in their activities. It was also found that these compounds tend to aggregate and exhibit toxic effects. They were found to contribute to: (a) DNA damage, (b) increased ROS production, and (c) disruption of cell cycle progression. It was observed that, HepG2, occurred much more sensitive to the tested chemicals than the HUH7 cells; However, regardless of the used cell line it seems that the increase in the expression of HK2 in cancer cells compared to normal cells which have HK2 at a very low level, is a serious obstacle in anti-cancer therapy and efforts to find the effective inhibitors of this enzyme should be intensified