Citation
Ang, Kok Pian
(2017)
Molecular mechanisms underlying antiproliferative effect of tricyclohexylphosphine gold (i) mercaptobenzoate derivatives on human breast and ovarian carcinoma cell lines.
Doctoral thesis, Universiti Putra Malaysia.
Abstract
Breast and ovarian cancers are in the list of top three female cancers. Hormonal
problem and family genetic background play important role in these two types of
cancer. In cancer research, p53 deems to be the key regulator in the apoptosis
events (intrinsic and extrinsic). Many studies have been focusing on the
therapeutic effects of the metal complexes including gold complexes due to its
potential in exhibiting various medical therapeutic benefits. Thus, a series of gold
complexes has been synthesized from the precursor tricyclohexylphosphine gold
(I) and mercaptobenzoic acid ligands. The Tricyclohexylphosphinegold (I) Rmercaptobenzoate
derivatives are yielded at different ligand position of ortho (2),
meta (3) and para (4), labelled as CAU2, CAU3 and CAU4, respectively. The
antiproliferative effect and their underlying mechanism(s) were investigated on
both breast (MCF-7R) and ovarian (A2780) cancer cell lines via various in vitro
assays. Molecular mechanisms of p53 of both cells upon treatments were
analysed via Human p53 signaling pathway RT2 profiler PCR array with all other
supportive parameters such as cell proliferation, DNA fragmentation, cell invasion,
cell cycle analysis, Anexin V/FITC and caspases (3, 8, 9 and 10). All compounds
(CAU2, CAU3 and CAU4) exhibited strong cytotoxicity against MCF-7R and
A2780 cell lines with IC50 of 8.14 μM, 7.26 μM and 9.03 μM against the former cell
lines and 1.19 μM, 2.28 μM and 0.785 μM against the latter cell lines, respectively.
Apoptotic cell death was confirmed by DNA fragmentation and Annexin V assay,
respectively. The treated compounds also induced caspases (caspase-3/7, -8, -9,
-10) expressions at both cancer cells which led to apoptosis. Both types of cancer
cells were arrested at S-phase checkpoint upon treatment with the treated
compounds. All treated compounds were shown to induce both intrinsic and
extrinsic apoptotic pathways, supported and confirmed by the data obtained from Human p53 signaling pathway RT2 profiler PCR array and caspases activities
assay, respectively. The compounds were also able to significantly modulate
several important gene expressions such as p53, p73 and Bax via upregulation
whilst simultaneously downregulated key anti-apoptotic gene bcl-2.
Downregulation of MDM2 gene has also been observed, as it served as the
destructive factor for p53 gene. The compounds also inhibited the NF-κB signaling
pathway via activation of Lys48-linked polyubiquitination thus led to NF-κB
degradation. Furthermore, the accumulation of reactive oxygen species (ROS)
was observed upon the compounds’ treatment, indicating the ROS generation
thus led to the increment of mitochondrial membrane potential (MMP).
Consequently, this led to the increase of cytochrome c releases from
mitochondria, manifested by the results obtained by flow cytometric analysis. In
conclusion, CAU2, CAU3 and CAU 4 exhibited significant anticancer effects
against both breast and ovarian cancer by inducing intrinsic and extrinsic apoptotic
cell death, respectively. These findings shed a light for furthering the research in
the new discovery of novel chemotherapeutic agents.
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