Green synthesis approach for nanoparticle is environmental friendly, non-hazardous and the nanoparticles have shown enhanced biocompatibility for application in healthcare. Previous reviews have mentioned about green synthesis methods for nanoparticles and their biological activities. This review not only covers the general information about green synthesis of silver nanoparticles and characterization, but also focused on recent uses of various medicinal and nonmedical plants based AgNPs synthesis and their broad-spectrum antimicrobial and anticancer activities. In addition, this review emphasizes on elaborating underlying mechanism of anti-pathogenic microbial and anticancer activities of plant based AgNPs. Thus, present article provides a comprehensive analysis of plant-mediated synthesis of AgNPs and their potential applications in biomedical field including their mode of action and challenges in a single window.
Using
oral cancer cells (in vitro) and in
vivo xenograft mice model, we have systematically
studied the detailed mechanism of anticancer activity of quinacrine-based
hybrid silver (QAgNP) and gold (QAuNP) nanoparticles (NPs) and compared
their efficacies. Both the NPs showed characteristic anti-cell proliferation
profile in various cancer cells with minimally affecting the normal
nontransformed breast epithelial MCF-10A cells. The IC50 values of QAuNP in various cancer cells were less compared to QAgNP
and also found to be the lowest (0.5 μg/mL) in SCC-9 oral cancer
cells. Although both NPs caused apoptosis by increased DNA damage,
arresting at S phase and simultaneously inhibiting the DNA repair
activity in cells, efficacy of QAuNP was better than that of QAgNP.
NPs intercalated with DNA and inhibited the topoisomerase activity
in cells. Alteration in expression of cell cycle regulatory (cyclins
B1, E1, A2, etc.) and replication-related (MRE11, RPA, RFC, etc.)
proteins were also observed after NP exposure to the cells. Accumulation
of cells resulted in extended G/M phase after prolonged exposure of
QAuNP in SCC-9 cells. Interestingly, depletion of geminin and increase
of Cdt-1 along with CDC-6 suggest the formation of re-replication.
Recovery of body weight and reduction in tumor volume were found in
NP-treated xenograft mice. Induction of Bax/Bcl-xL, PARP-1 cleavage,
p53, and p21 were noted in NP-treated xenograft mice tissue samples.
Thus, data suggest that NP inhibits topoisomerase activity, thereby
inhibiting DNA replication and inducing re-replication, which causes
S-phase arrest, DNA damage, and finally apoptosis of the oral cancer
cells. Also, it was found that anticancer activity of QAuNP is better
than that of QAgNP.
Published database suggests of several methods which have been developed for the preparation and characterization of chitosan nanoparticles as per the application.
The
presence of cancer stem cells (CSCs) in the tumor microenvironment
is responsible for the development of chemoresistance and recurrence
of cancer. Our previous investigation revealed the anticancer mechanism
of quinacrine-based silver and gold hybrid nanoparticles (QAgNP and
QAuNP) in oral cancer cells, but to avoid cancer recurrence, it is
important to study the effect of these nanoparticles (NPs) on CSCs.
Here, we developed an in vitro CSCs model using SCC-9
oral cancer cells and validated via FACS analysis. Then, 40–60%
of cells were found to be CD44+/CD133+ and CD24–. QAuNP showed
excellent anti-CSC growth potential against SCC-9-cancer stem like
cells (IC50 = 0.4 μg/mL) with the down-regulation
of representative CSC markers. Prolonged exposure of QAuNP induced
the S-phase arrest and caused re-replication shown by the extended
G2/M population and apoptosis to SCC-9-CSC like cells. Up-regulation
of BAX, PARP cleavage, and simultaneous down-regulation of Bcl-xL
in prolonged treatment to CSCs suggested that the majority of the
cells have undergone apoptosis. QAuNP treatment also caused a loss
in DNA repair in CSCs. Mostly, the base excision repair (BER) components
(Fen-1, DNA ligase-1, Pol-β, RPA, etc.) were significantly down-regulated
after QAuNP treatment, which suggested its action against DNA repair
machinery. The replication fork maintenance-related proteins, RAD
51 and BRCA-2, were also deregulated. Very surprisingly, depletion
of WRN (an interacting partner for Pre-RC and Fen-1) and a significant
increase in expression of fork-degrading nuclease MRE-11 in 96 h treated
NPs were observed. Results suggest QAuNP treatment caused excessive
DNA damage and re-replication mediated replication stress (RS) and
stalling of the replication fork. Inhibition of BER components hinders
the flap clearance activity of Fen-1, and it further caused RS and
stopped DNA synthesis. Overall, QAuNP treatment led to irreparable
replication fork movement, and the stalled replication fork might
have degraded by MRE-11, which ultimately results in apoptosis and
the death of the CSCs.
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