Comparison of structures and cytotoxicity of mupirocin and batumin against melanoma and several other cancer cell lines

AIM : To determine the computer-predicted anticancer activity of mupirocin and to compare its activities with those determined for another polyene antibiotic, batumin. MATERIALS AND METHODS : Molecular docking, cytotoxicity assays, cell microscopy and cell cycle progression were studied in cancer and nontumorigenic cell lines. RESULTS AND CONCLUSION : Cytotoxicity of mupirocin against several cancerous cell lines was detected with the highest one (IC50 = 5.4 μg/ml) against melanoma cell line. The profile of cytotoxicity of mupirocin was similar to that reported for batumin. Nevertheless, the morphology of cells treated with these antibiotics and alterations in cell cycle progression suggested possible dissimilarity in their mechanisms of action. Selective cytotoxicity of mupirocin against melanoma cells potentiates further studies to discover nontoxic drugs for melanoma prevention.AM Joubert acquired grants from the National Research Foundation (NRF; 105992, 90523 and 85818), Cancer Association of South Africa (A0V741 and A0W228), the Struwig Germeshuysen Trust (A0N074), the School of Medicine Research Committee of the University of Pretoria (AOH561) and Medical Research Council (A0W110). MH Visagie was funded from the NRF (99706), the School of Medicine Research Committee of the University of Pretoria (AOH561) and Struwig Germeshysen Trust. N Lall was funded from NRF/IKS160514165042 Grant No: 105169. ON Reva was funded from NRF grant 105996.https://www.future-science.com/journal/fmchj2019BiochemistryGeneticsMicrobiology and Plant PathologyPhysiologyPlant Production and Soil Scienc

Promising anticancer activity of batumin : a natural polyene antibiotic produced by Pseudomonas batumici

AIM : To determine the computer-predicted anticancer activity of antibiotic batumin. MATERIALS AND METHODS : Cytotoxicity assays, cell morphology microscopy and cell cycle progression were studied in cancer and nontumorigenic cell lines. An in vivo experiment on Lewis lung carcinoma (3LL)-transplanted mice was conducted to evaluate potential antimetastatic. RESULTS AND CONCLUSION : Cytotoxicity against melanoma and lung carcinoma cells (IC50 ≈ 5 μg/ml) was detected. Hypercondensed chromatin and apoptotic body formation in batumin-treated cells suggested the induction of apoptosis supported also by an observed increase in the quantity of cells occupying the sub-G1 cell cycle phase. Twofold reduction in the number and volume of lung metastases in Lewis lung carcinoma (3LL)-bearing batumin-treated mice was demonstrated. Highly specific cytotoxicity of batumin against cancer cell lines potentiates further studies.https://www.future-science.com/loi/fmc2019-09-01hj2018BiochemistryGeneticsMicrobiology and Plant PathologyPhysiologyPlant Production and Soil Scienc

Effects of glutamine deprivation on oxidative stress and cell survival in breast cell lines

Tumourigenic cells utilize aberrant metabolic process that supports the biosynthetic requirements for hyperproliferation, survival and prolonged maintenance characterised by glucose metabolism to lactate dehydrogenase independent of oxygen availability (Warburg effect). In addition, tumourigenic cells exert increased glycolytic- and glutaminolytic activity in order to provide increased quantities of adenosine triphosphate. The aim of this research project was to investigate the influence of glutamine deprivation on proliferation, morphology, oxidative stress, mitochondrial membrane potential, cell cycle progression, antioxidant defences, deoxyribonucleic acid (DNA) damage, energy status, cell survival signaling and cell death induction in tumourigenic- and non-tumourigenic breast cell lines. In this study it was found that glutamine deprivation results in differential antiproliferative activity where the MCF-7 cell line was the most affected with decreased cell growth to 61% after 96 h of glutamine deprivation. Aberrant redox activity was most prominently observed in the MCF-7 cell line accompanied with biphasic mitochondrial membrane potential- and reactive oxygen species production. The MCF-7 cell line showed significant mitochondrial membrane depolarisation after 24 h and 96 h deprivation from glutamine (1.5- and 1.37 fold). Cell cycle progression analysis illustrated an increase in the amount of cells present in the S-phase in the MCF-7 cell line after 72 h of glutamine deprivation. The MDA-MB-231 cell line resulted in a significant increase in cells occupying the G2/M phase after 24 h of glutamine deprivation. Glutamine deprivation in the BT-20 cell line resulted in a significant increase in cells occupying G1 phase after 72 h of glutamine deprivation. The MCF-7 cell line demonstrated the least amount of viable cells when analysing apoptosis induction, when compared to the MDA-MB-231-, MCF-10A- and BT-20 cell lines after glutamine deprivation suggesting that the MCF-7 cell line is the most affected cell line. Analysis of antioxidant mechanism via superoxide dismutase (SOD) inhibition illustrated increased SOD activity in the MCF-7 cell line (9.1%) after 72 h of glutamine deprivation. Evaluation of catalase protein concentration indicated that the MCF-7 catalase expression increased to 1.28 fold after 24 h of glutamine deprivation when compared to cell propagated in complete growth medium. DNA damage was demonstrated by visualising the presence of fluorescent 8-hydroxydeoxyguanosine and showed that the MCF-7 cell line presented with significant 8-hydroxydeoxyguanosine staining. Survival signaling was also evaluated through visualising extracellular signal-regulated kinase (ERK) and phosphoinositide 3-kinase (PI3K) signaling which demonstrated increased ERK activation in the non-tumourigenic MCF-10A cell line and decreased PI3K activation. This study provides evidence that there are differential- and time-dependent responses in breast tumourigenic cells versus non-tumourigenic cells, to glutamine deprivation thus unraveling the crosstalk between glutamine deprivation, oxidative stress and cell death and different cell types will enable us to better understand the basics of tumour cell metabolism and thus develop therapeutics that provide promising pre-sensitization potential for chemotherapeutic agents.Dissertation (MSc)--University of Pretoria, 2020.PhysiologyMScUnrestricte

Effects of glutamine deprivation on oxidative stress and cell survival in breast cell lines

Abstract Background Tumourigenic cells modify metabolic pathways in order to facilitate increased proliferation and cell survival resulting in glucose- and glutamine addiction. Previous research indicated that glutamine deprivation resulted in potential differential activity targeting tumourigenic cells more prominently. This is ascribed to tumourigenic cells utilising increased glutamine quantities for enhanced glycolysis- and glutaminolysis. In this study, the effects exerted by glutamine deprivation on reactive oxygen species (ROS) production, mitochondrial membrane potential, cell proliferation and cell death in breast tumourigenic cell lines (MCF-7, MDA-MB-231, BT-20) and a non-tumourigenic breast cell line (MCF-10A) were investigated. Results Spectrophotometry demonstrated that glutamine deprivation resulted in decreased cell growth in a time-dependent manner. MCF-7 cell growth was decreased to 61% after 96 h of glutamine deprivation; MDA-MB-231 cell growth was decreased to 78% cell growth after 96 h of glutamine deprivation, MCF-10A cell growth was decreased 89% after 96 h of glutamine deprivation and BT-20 cell growth decreased to 86% after 24 h of glutamine deprivation and remained unchanged until 96 h of glutamine deprivation. Glutamine deprivation resulted in oxidative stress where superoxide levels were significantly elevated after 96 h in the MCF-7- and MDA-MB-231 cell lines. Time-dependent production of hydrogen peroxide was accompanied by aberrant mitochondrial membrane potential. The effects of ROS and mitochondrial membrane potential were more prominently observed in the MCF-7 cell line when compared to the MDA-MB-231-, MCF-10A- and BT-20 cell lines. Cell cycle progression revealed that glutamine deprivation resulted in a significant increase in the S-phase after 72 h of glutamine deprivation in the MCF-7 cell line. Apoptosis induction resulted in a decrease in viable cells in all cell lines following glutamine deprivation. In the MCF-7 cells, 87.61% of viable cells were present after 24 h of glutamine deprivation. Conclusion This study demonstrates that glutamine deprivation resulted in decreased cell proliferation, time-dependent- and cell line-dependent ROS generation, aberrant mitochondrial membrane potential and disrupted cell cycle progression. In addition, the estrogen receptor positive MCF-7 cell line was more prominently affected. This study contributes to knowledge regarding the sensitivity of breast cancer cells and non-tumorigenic cells to glutamine deprivation

Crosstalk between the Warburg effect, redox regulation and autophagy induction in tumourigenesis

Abstract Tumourigenic tissue uses modified metabolic signalling pathways in order to support hyperproliferation and survival. Cancer-associated aerobic glycolysis resulting in lactic acid production was described nearly 100 years ago. Furthermore, increased reactive oxygen species (ROS) and lactate quantities increase metabolic, survival and proliferation signalling, resulting in increased tumourigenesis. In order to maintain redox balance, the cell possesses innate antioxidant defence systems such as superoxide dismutase, catalase and glutathione. Several stimuli including cells deprived of nutrients or failure of antioxidant systems result in oxidative stress and cell death induction. Among the cell death machinery is autophagy, a compensatory mechanism whereby energy is produced from damaged and/or redundant organelles and proteins, which prevents the accumulation of waste products, thereby maintaining homeostasis. Furthermore, autophagy is maintained by several pathways including phosphoinositol 3 kinases, the mitogen-activated protein kinase family, hypoxia-inducible factor, avian myelocytomatosis viral oncogene homolog and protein kinase receptor-like endoplasmic reticulum kinase. The persistent potential of cancer metabolism, redox regulation and the crosstalk with autophagy in scientific investigation pertains to its ability to uncover essential aspects of tumourigenic transformation. This may result in clinical translational possibilities to exploit tumourigenic oxidative status and autophagy to advance our capabilities to diagnose, monitor and treat cancer