NAADP Dotaz Zobrazit nápovědu
In tumor cells with defects in apoptosis, autophagy allows prolonged survival. Autophagy leads to an accumulation of damaged mitochondria by autophagosomes. An acidic environment is maintained in compartments of cells, such as autophagosomes, late endosomes, and lysosomes; these organelles belong to the "acid store" of the cells. Nicotinic acid adenine dinucleotide phosphate (NAADP) may affect the release of Ca2+ from these organelles and affect the activity of Ca2+ ATPases and other ion transport proteins. Recently, a growing amount of evidence has shown that the variations in the expression of calcium channels or pumps are associated with the occurrence, disease-presentation, and the prognosis of colorectal cancer. We hypothesized that activity of ATPases in cancer tissue is higher because of intensive energy metabolism of tumor cells. The aim of our study was to ascertain the effect of NAADP on ATPase activity on tissue samples of colorectal cancer patients' and healthy individuals. We tested the effect of NAADP on the activity of Na+/K+ ATPase; Ca2+ ATPase of endoplasmic reticulum (EPR) and plasma membrane (PM) and basal ATPase activity. Patients' colon mucus cancer samples were obtained during endoscopy from cancer and healthy areas (control) of colorectal mucosa of the same patients. Results. The mean activity of Na+/K+ pump in samples of colorectal cancer patients (n = 5) was 4.66 ± 1.20 μmol Pi/mg of protein per hour, while in control samples from healthy tissues of the same patient (n = 5) this value was 3.88 ± 2.03 μmol Pi/mg of protein per hour. The activity of Ca2+ ATPase PM in control samples was 6.42 ± 0.63 μmol Pi/mg of protein per hour and in cancer -8.50 ± 1.40 μmol Pi/mg of protein per hour (n = 5 pts). The mean activity of Ca2+ ATPase of EPR in control samples was 7.59 ± 1.21 μmol Pi/mg versus 7.76 ± 0.24 μmol Pi/mg in cancer (n = 5 pts). Basal ATPase activity was 3.19 ± 0.87 in control samples versus 4.79 ± 1.86 μmol Pi/mg in cancer (n = 5 pts). In cancer samples, NAADP reduced the activity of Na+/K+ ATPase by 9-times (p < 0.01) and the activity of Ca2+ ATPase EPR about 2-times (p < 0.05). NAADP caused a tendency to decrease the activity of Ca2+ ATPase of PM, but increased basal ATPase activity by 2-fold vs. the mean of this index in cancer samples without the addition of NAADP. In control samples NAADP caused only a tendency to decrease the activities of Na+/K+ ATPase and Ca2+ ATPase EPR, but statistically decreased the activity of Ca2+ ATPase of PM (p < 0.05). In addition, NAADP caused a strong increase in basal ATPase activity in control samples (p < 0.01). Conclusions: We found that the activity of Na+/K+ pump, Ca2+ ATPase of PM and basal ATPase activity in cancer tissues had a strong tendency to be higher than in the controls. NAADP caused a decrease in the activities of Na+/K+ ATPase and Ca2+ ATPase EPR in cancer samples and increased basal ATPase activity. In control samples, NAADP decreased Ca2+ ATPase of PM and increased basal ATPase activity. These data confirmed different roles of NAADP-sensitive "acidic store" (autophagosomes, late endosomes, and lysosomes) in control and cancer tissue, which hypothetically may be connected with autophagy role in cancer development. The effect of NAADP on decreasing the activity of Na+/K+ pump in cancer samples was the most pronounced, both numerically and statistically. Our data shows promising possibilities for the modulation of ion-transport through the membrane of cancer cells by influence on the "acidic store" (autophagosomes, late endosomes and lysosomes) as a new approach to the treatment of colorectal cancer.
- Publikační typ
- časopisecké články MeSH
Bafilomycin A1 inhibits V-type H+ ATPases on the molecular level, which acidifies endo-lysosomes. The main objective of the study was to assess the effect of bafilomycin A1 on Ca2+ content, NAADP-induced Ca2+ release, and ATPase activity in rat hepatocytes and human colon cancer samples. Chlortetracycline (CTC) was used for a quantitative measure of stored calcium in permeabilized rat hepatocytes. ATPase activity was determined by orthophosphate content released after ATP hydrolysis in subcellular post-mitochondrial fraction obtained from rat liver as well as from patients' samples of colon mucosa and colorectal cancer samples. In rat hepatocytes, bafilomycin A1 decreased stored Ca2+ and prevented the effect of NAADP on stored Ca2+. This effect was dependent on EGTA-Ca2+ buffers in the medium. Bafilomycin A1 significantly increased the activity of Ca2+ ATPases of endoplasmic reticulum (EPR), but not plasma membrane (PM) Ca2+ ATPases in rat liver. Bafilomycin A1 also prevented the effect of NAADP on these pumps. In addition, bafilomycin A1 reduced Na+/K+ ATPase activity and increased basal Mg2+ ATPase activity in the subcellular fraction of rat liver. Concomitant administration of bafilomycin A1 and NAADP enhanced these effects. Bafilomycin A1 increased the activity of the Ca2+ ATPase of EPR in the subcellular fraction of normal human colon mucosa and also in colon cancer tissue samples. In contrast, it decreased Ca2+ ATPase PM activity in samples of normal human colon mucosa and caused no changes in colon cancer. Bafilomycin A1 decreased Na+/K+ ATPase activity and increased basal Mg2+ ATPase activity in normal colon mucosa samples and in human colon cancer samples. It can be concluded that bafilomycin A1 targets NAADP-sensitive acidic Ca2+ stores, effectively modulates ATPase activity, and assumes the link between acidic stores and EPR. Bafilomycin A1 may be useful for cancer therapy.
- MeSH
- játra metabolismus MeSH
- kolorektální nádory * MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- makrolidy farmakologie MeSH
- nádory tračníku * MeSH
- subcelulární frakce metabolismus MeSH
- vakuolární protonové ATPasy * metabolismus MeSH
- vápník metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Lysosomal sequestration of anticancer therapeutics lowers their cytotoxic potential, reduces drug availability at target sites, and contributes to cancer resistance. Only recently has it been shown that lysosomal sequestration of weak base drugs induces lysosomal biogenesis mediated by activation of transcription factor EB (TFEB) which, in turn, enhances their accumulation capacity, thereby increasing resistance to these drugs. Here, we addressed the question of whether lysosomal biogenesis is the only mechanism that increases lysosomal sequestration capacity. We found that lysosomal sequestration of some tyrosine kinase inhibitors (TKIs), gefitinib (GF) and imatinib (IM), induced expansion of the lysosomal compartment. However, an expression analysis of lysosomal genes, including lysosome-associated membrane proteins 1, 2 (LAMP1, LAMP2), vacuolar ATPase subunit B2 (ATP6V1B2), acid phosphatase (ACP), and galactosidase beta (GLB) controlled by TFEB, did not reveal increased expression. Instead, we found that both studied TKIs, GF and IM, induced lysosomal fusion which was dependent on nicotinic acid adenine dinucleotide phosphate (NAADP) mediated Ca2+signaling. A theoretical analysis revealed that lysosomal fusion is sufficient to explain the enlargement of lysosomal sequestration capacity. In conclusion, we demonstrated that extracellular TKIs, GF and IM, induced NAADP/Ca2+ mediated lysosomal fusion, leading to enlargement of the lysosomal compartment with significantly increased sequestration capacity for these drugs without apparent lysosomal biogenesis.
- MeSH
- antitumorózní látky farmakologie MeSH
- biogeneze organel MeSH
- buňky K562 MeSH
- chemorezistence účinky léků MeSH
- gefitinib farmakologie MeSH
- imatinib mesylát farmakologie MeSH
- lidé MeSH
- lyzozomy účinky léků metabolismus MeSH
- nádorové buněčné linie MeSH
- signální transdukce účinky léků MeSH
- transkripční faktory BHLH-Zip účinky léků metabolismus MeSH
- tyrosinkinasy antagonisté a inhibitory MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Colorectal cancer is influenced by genetic mutations, lifestyle factors, and diet, particularly high fat intake, which raises bile acid levels in the intestinal lumen. This study hypothesized that bile acids contribute to tumorigenesis by disrupting ion transport and ATPase activity in the intestinal mucosa. The effects of 3-sulfo-taurolithocholic acid (TLC-S) on ATPase activity were investigated in colorectal cancer samples from 10 patients, using adjacent healthy tissue as controls, and in rodent liver function. ATPase activity was measured spectrophotometrically by determining inorganic phosphorus (Pi) in postmitochondrial fractions. Ca2+ dynamics were assessed in isolated mouse hepatocytes with fluorescence imaging, and rat liver mitochondria were studied using polarographic methods to evaluate respiration and oxidative phosphorylation. TLC-S increased Na+/K+ ATPase activity by 1.5 times in colorectal cancer samples compared to controls (p ≤ 0.05). In healthy mucosa, TLC-S decreased Mg2+ ATPase activity by 3.6 times (p ≤ 0.05), while Mg2+ ATPase activity in cancer tissue remained unchanged. TLC-S had no significant effect on Ca2+ ATPase activity in healthy colon mucosa but showed a trend toward decreased activity in cancer tissue. In rat liver, TLC-S decreased Ca2+ ATPase and Na+/K+ ATPase activities while increasing basal Mg2+ ATPase activity (p ≤ 0.05). Additionally, TLC-S induced cytosolic Ca2+ signals in mouse hepatocytes, partially attenuated by NED-19, an NAADP antagonist (p ≤ 0.05). TLC-S also reduced the V3 respiration rate of isolated rat liver mitochondria during α-ketoglutarate oxidation. These findings suggest that TLC-S modulates ATPase activity differently in cancerous and healthy colon tissues, playing a role in colorectal cancer development. In rat liver, TLC-S affects mitochondrial activity and ATPase function, contributing to altered cytosolic calcium levels, providing insight into the mechanistic effects of bile acids on colorectal cancer and liver function.
- Publikační typ
- časopisecké články MeSH
