Celecoxib and Dimethylcelecoxib Block Oxidative Phosphorylation, Epithelial-Mesenchymal Transition and Invasiveness in Breast Cancer Stem Cells.

BACKGROUND: The major hurdles for successful cancer treatment are drug resistance and invasiveness developed by breast cancer stem cells (BCSC). OBJECTIVE: As these two processes are highly energy-dependent, the identification of the main ATP supplier required for stem cell viability may result advantageous in the design of new therapeutic strategies to deter malignant carcinomas. METHODS: The energy metabolism (glycolysis and oxidative phosphorylation, OxPhos) was systematically analyzed by assessing relevant protein contents, enzyme activities, and pathway fluxes in BCSC. Once identified as the main ATP supplier, selective energy inhibitors and canonical breast cancer drugs were used to block stem cell viability and metastatic properties. RESULTS: OxPhos and glycolytic protein contents, as well as HK and LDH activities were several times higher in BCSC than in their parental line, MCF-7 cells. However, CS, GDH, COX activities, and both energy metabolism pathway fluxes were significantly lower (38-86%) in BCSC than in MCF-7 cells. OxPhos was the main ATP provider (>85%) in BCSC. Accordingly, oligomycin (a specific and potent canonical OxPhos inhibitor) and other non-canonical drugs with inhibitory effect on OxPhos (celecoxib, dimethylcelecoxib) significantly decreased BCSC viability, levels of epithelial-mesenchymal transition proteins, invasiveness, and induced ROS over-production, with IC50 values ranging from 1 to 20 µM in 24 h treatment. In contrast, glycolytic inhibitors (gossypol, iodoacetic acid, 3-bromopyruvate, 2-deoxyglucose) and canonical chemotherapeutic drugs (paclitaxel, doxorubicin, cisplatin) were much less effective against BCSC viability (IC50> 100 µM). CONCLUSION: These results indicated that the use of some NSAIDs may be a promising alternative therapeutic strategy to target BCSC.

Non-Steroidal Anti-Inflammatory Drugs Increase Cisplatin, Paclitaxel, and Doxorubicin Efficacy against Human Cervix Cancer Cells.

This study shows that the non-steroidal anti-inflammatory drug (NSAID) celecoxib and its non-cyclooxygenase-2 (COX2) analogue dimethylcelecoxib (DMC) exert a potent inhibitory effect on the growth of human cervix HeLa multi-cellular tumor spheroids (MCTS) when added either at the beginning ("preventive protocol"; IC50 = 1 ± 0.3 nM for celecoxib and 10 ± 2 nM for DMC) or after spheroid formation ("curative protocol"; IC50 = 7.5 ± 2 µM for celecoxib and 32 ± 10 µM for DMC). These NSAID IC50 values were significantly lower than those attained in bidimensional HeLa cells (IC50 = 55 ± 9 µM celecoxib and 48 ± 2 µM DMC) and bidimensional non-cancer cell cultures (3T3 fibroblasts and MCF-10A mammary gland cells with IC50 from 69 to >100 µM, after 24 h). The copper-based drug casiopeina II-gly showed similar potency against HeLa MCTS. Synergism analysis showed that celecoxib, DMC, and casiopeinaII-gly at sub-IC50 doses increased the potency of cisplatin, paclitaxel, and doxorubicin to hinder HeLa cell proliferation through a significant abolishment of oxidative phosphorylation in bidimensional cultures, with no apparent effect on non-cancer cells (therapeutic index >3.6). Similar results were attained with bidimensional human cervix cancer SiHa and human glioblastoma U373 cell cultures. In HeLa MCTS, celecoxib, DMC and casiopeina II-gly increased cisplatin toxicity by 41-85%. These observations indicated that celecoxib and DMC used as adjuvant therapy in combination with canonical anti-cancer drugs may provide more effective alternatives for cancer treatment.

Omeprazole as a potent activator of human cytosolic aldehyde dehydrogenase ALDH1A1.

BACKGROUND: Accumulation of lipid aldehydes plays a key role in the etiology of human diseases where high levels of oxidative stress are generated. In this regard, activation of aldehyde dehydrogenases (ALDHs) prevents oxidative tissue damage during ischemia-reperfusion processes. Although omeprazole is used to reduce stomach gastric acid production, in the present work this drug is described as the most potent activator of human ALDH1A1 reported yet. METHODS: Docking analysis was performed to predict the interactions of omeprazole with the enzyme. Recombinant human ALDH1A1 was used to assess the effect of omeprazole on the kinetic properties. Temperature treatment and mass spectrometry were conducted to address the nature of binding of the activator to the enzyme. Finally, the effect of omeprazole was evaluated in an in vivo model of oxidative stress, using E. coli cells expressing the human ALDH1A1. RESULTS: Omeprazole interacted with the aldehyde binding site, increasing 4-6 fold the activity of human ALDH1A1, modified the kinetic properties, altering the order of binding of substrates and release of products, and protected the enzyme from inactivation by lipid aldehydes. Furthermore, omeprazole protected E. coli cells over-expressing ALDH1A1 from the effects of oxidative stress generated by H2O2 exposure, reducing the levels of lipid aldehydes and preserving ALDH activity. CONCLUSION: Omeprazole can be repositioned as a potent activator of human ALDH1A1 and may be proposed for its use in therapeutic strategies, to attenuate the damage generated during oxidative stress events occurring in different human pathologies.

Transcriptional Regulation of Energy Metabolism in Cancer Cells.

Cancer development, growth, and metastasis are highly regulated by several transcription regulators (TRs), namely transcription factors, oncogenes, tumor-suppressor genes, and protein kinases. Although TR roles in these events have been well characterized, their functions in regulating other important cancer cell processes, such as metabolism, have not been systematically examined. In this review, we describe, analyze, and strive to reconstruct the regulatory networks of several TRs acting in the energy metabolism pathways, glycolysis (and its main branching reactions), and oxidative phosphorylation of nonmetastatic and metastatic cancer cells. Moreover, we propose which possible gene targets might allow these TRs to facilitate the modulation of each energy metabolism pathway, depending on the tumor microenvironment.