Abida Arshad

ROS-modulated therapeutic approaches in cancer treatment

PurposeReactive oxygen species (ROS) are produced in cancer cells as a result of increased metabolic rate, dysfunction of mitochondria, elevated cell signaling, expression of oncogenes and increased peroxisome activities. Certain level of ROS is required by cancer cells, above or below which lead to cytotoxicity in cancer cells. This biochemical aspect can be exploited to develop novel therapeutic agents to preferentially and selectively target cancer cells.MethodsWe searched various electronic databases including PubMed, Web of Science, and Google Scholar for peer-reviewed english-language articles. Selected articles ranging from research papers, clinical studies, and review articles on the ROS production in living systems, its role in cancer development and cancer treatment, and the role of microbiota in ROS-dependent cancer therapy were analyzed.ResultsThis review highlights oxidative stress in tumors, underlying mechanisms of different relationships of ROS and cancer cells, different ROS-mediated therapeutic strategies and the emerging role of microbiota in cancer therapy.ConclusionCancer cells exhibit increased ROS stress and disturbed redox homeostasis which lead to ROS adaptations. ROS-dependent anticancer therapies including ROS scavenging anticancer therapy and ROS boosting anticancer therapy have shown promising results in vitro as well as in vivo. In addition, response to cancer therapy is modulated by the human microbiota which plays a critical role in systemic body functions.

α-Synuclein increases U251 cells vulnerability to hydrogen peroxide by disrupting calcium homeostasis.

Multiple system atrophy (MSA) is a progressive neurodegenerative disease characterized by glial cytoplasmic inclusions containing insoluble α-synuclein. Since Ca2+ plays an important role in cell degeneration, [Ca2+]i in α-synuclein-overexpressed human glioma cells was analyzed by Fura-2 fluorometry. Overexpression of α-synuclein increased the basal level of [Ca2+]i, and a higher Ca2+ response to hydrogen peroxide was further observed. The effect that α-synuclein overexpression caused U251 cells to be more vulnerable to hydrogen peroxide was eliminated by Ca2+ chelator BAPTA-AM or transient receptor potential channels blocker SKF 96365 but not by L-type Ca2+ channel blocker nimodipine. These findings suggest that the dysregulation of cellular Ca2+ homeostasis caused by α-synuclein under oxidative stress may contribute to the glial cell death in MSA.

Enzymatic condensation of dopamine and acetaldehyde: a salsolinol synthase from rat brain

Salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline; Sal) is structurally similar to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, which is supposed to have a role in the development of Parkinson-like syndrome in both human and non-human subjects. In the human brain, the amount of (R)-enantiomer of Sal is much higher than (S)-enantiomer, suggesting that a putative enzyme may participate in the synthesis of (R)-salsolinol, called (R)-salsolinol synthase. In this study, the (R)-salsolinol synthase activity in the condensation of dopamine and acetaldehyde was investigated in the crude extracts from the brains of Sprague Dawley rats. Identification of the enzymatic reaction products and enzyme activity detection were achieved by HPLC-electrochemical detection. The discovery of this enzyme activity in rat’s brain indicates the natural existence of (R)-salsolinol synthase in the brains of humans and rats, and it is distributed in most brain regions of rat with higher activity in soluble proteins extracted from striatum and substantia nigra.

Changing Trends in Antibiogram and MolecularAnalysis of Quinolone Resistant Salmonellatyphi Isolates in Pakistan

Multidrug resistance is the ongoing burning issue in Salmonella typhi around the whole globe. This study was conducted to investigate changing trends in antibiotics resistance and mechanism of resistance against Nalidixic acid among multidrug resistant Salmonella typhi strains isolated from Islamabad Capital Territory, Pakistan. Methodology: Prior to blood sampling, demographic data of patients was recorded. A total of 103 clinical isolates from blood of typhoid patients were identified using microbiological techniques such as colony morphology, Gram’s staining and confirmed using standard biochemical techniques. For molecular confirmation, hyper variable region VI of flagellin fliC gene was targeted using PCR. Antibiogram of the isolates was tested by Kirby Bauer disc diffusion method using fifteen regularly used antibiotics. Efficacy of antibiotics was evaluated in respect to various seasons, age groups and gender of patients. Relevant genes gyrA and gyrB were targeted and quinolone resistance determining region (QRDR) of these genes was sequenced to analyze mutations. Results: Antibiogram study demonstrated that 90.3% isolates were multidrug resistant. 75.7% isolates were sensitive to cefipime while 80.58% were resistant to nalidixic acid. 66.02% isolates were found to be ciprofloxacin resistant exposing reduced susceptibility of salmonella typhi to fluoroquinolones. Molecular studies revealed a single point mutation with substitution of serine-83 by phenyl-alanine. This single point mutation seems to be responsible for resistance against nalidixic acid in S. typhi. Conclusion: The incidence of typhoid is high in Islamabad with significant resistance of S. typhi isolates against currently administrated antibiotics due to the presence of one point mutation. Therefore, it must be mandatory for the health care professionals to test for the antibiogram before prescribing appropriate antibiotics.

RNF13 protein regulates endoplasmic reticulum stress induced apoptosis in dopaminergic SH-SY5Y cells by enhancing IRE1α stability.

Abstract Any interruption in the folding capacity of endoplasmic reticulum (ER) may result in inducing ER stress which would initiate an adaptive signaling mechanism called Unfolded Protein Response (UPR) in order to restore homeostasis, failing to which would initiate signaling pathway leading to death of the cell. Finding new mediators could help better understand the molecular mechanisms of ER stress-induced apoptosis. Our lab initiated a genetic screen method using retroviral insertion mutation system to look for genes whose inactivation would confer resistance to apoptosis. In our previous findings, Ring finger protein 13 (RNF13) was identified whose down-regulation conferred survival against ER stress-induced apoptosis. Our previous results also showed important role of RNF13 in apoptotic signaling in 293T cells as a result of strong RNF13-IRE1α interaction. In current study, using SH-SY5Y cells, overexpression of RNF13 in apoptosis assays and RT-PCR analysis has shown to induce apoptosis as well as splicing of X-box binding Protein 1 (XBP1) confirming its role in ER stress mediated cell death in this cell line as well. Western blot analysis has revealed that overexpression of both N-terminal as well as C-terminal tagged RNF13 resulted in activation of c-Jun N-terminal kinase (JNK) in SH-SY5Y cells. Our co-immunoprecipitation assays in SH-SY5Y cells also showed a strong interaction of RNF13 with IRE1α. Finally, Cycloheximide chase experiment exhibited that RNF13-IRE1α interaction increased the stability of IRE1α. Altogether, our data suggest that RNF13 may act as an important regulator of IRE1α, mediating ER stress-mediated apoptosis in neuroblastoma SH-SY5Y cells.