Synthesis of silver and silver based nanoparticles using microorganisms has received profound interest because of obtaining nanoparticles with unique physicochemical and biological properties. In the current study, for the first time, synthesis of silver chloride nanoparticles (AgClNPs) using cell-free supernatant of Escherichia coli culture is reported. Prepared AgClNPs were characterized by EDS, XRD and FESE. Data revealed the synthesized nanoparticles, mostly, have a spherical shape with an average size of 13 nm. Additionally, MTT assay elucidated a dose-dependent cytotoxicity of AgClNPs against MCF-7 cells (IC 50 ¼ 44 mg/mL). Quantitative real-time reverse transcription-PCR and colourimetric assays were employed to investigate the mechanism of cell toxicity in several cell death pathways. The results revealed the ability of AgClNPs to upregulate Bax/Bcl-2 ratio and p53 at mRNA level. Moreover, other apoptotic factors such as caspase-3, 8 and 9 were also upregulated at both mRNA and proteome levels. Finally, apoptosis induction was confirmed by Annexin-V/PI detection assay. Based on the obtained data, biosynthesized AgClNPs using E. coli cell-free supernatant exhibit a cytotoxic effect on human breast cancer cells through up-regulation of apoptotic factors, which suggest them as anti-tumour agents for further investigations.

Background: One of the most widely used anticancer agents is microbial L-ASNase. Herein, we assessed the biochemical and biological properties of an isolated L-ASNase from a Gram-negative bacteria strain, Escherichia coli MF-107. Methods: Using garden asparagus, we obtained several bacterial isolates. These strains were further screened for L-ASNase activity. A promising bacterial isolate was selected for L-ASNase production and subsequent purification. The molecular weight of purified L-ASNase was determined. The MTT assay was applied to assess the cytotoxic effect of the purified enzyme. Also, for caspase activity determination and the apoptotic effect of purified enzyme on in cells, we conducted a real-time PCR method. Results: The molecular weight of the enzyme was approximately 37 kDa. In the pH range of 7.5 to 8, the enzyme had considerable stability. At 35 °C, the purified L-ASNase optimum activity was recorded. The cytotoxic effect of the enzyme on treated cells was dose-dependent with an IC 50 value of 5.7 IU/ml. The Bax gene expression considerably raised by 5.75-fold ( p < 0.001) upon L-ASNase treatment. On the other hand, the anti-apoptotic Bcl-2 gene expression showed a 2.63-fold increase compared to the control ( p < 0.05). It was detected that the mRNA levels of caspase-3 and p53 were considerably upregulated (5.93 and 1.85-fold, respectively). We did not find any alternation in the caspase-8 activity of the treated cells compared to untreated cells. Conclusion: In this research, the proliferation of the breast cancer cells remarkably inhibited via the cytotoxic effect of isolated L-ASNase from microbial sources.