Introduction
Breast cancer remains the most prevalent malignancy among women globally, posing significant
challenges due to its high morbidity and mortality rates.[1] According to recent statistics, breast cancer accounts for approximately 30% of
all new cancer diagnoses in women and is a leading cause of cancer-related deaths
worldwide.[2] The disease is characterized by heterogeneous clinical manifestations, ranging from
localized tumors to aggressive metastatic forms.[3] Despite advancements in early detection, through screening methods such as mammography,
and in therapeutic strategies, including surgery, radiation, chemotherapy, hormonal
therapy, and targeted therapies, the management of breast cancer continues to face
critical obstacles.[4] These include the development of resistance to conventional treatments and a substantial
risk of recurrence, contributing to poor prognostic outcomes.[5]
Curcumin, a polyphenolic compound derived from the rhizome of Curcuma longa (turmeric), has garnered extensive attention for its potential therapeutic properties
in various diseases, including cancer.[6] Historically utilized in traditional medicine, curcumin exhibits a broad spectrum
of biological activities, notably its anti-inflammatory, antioxidant, and antitumor
effects.[7] These properties are primarily attributed to curcumin's ability to modulate multiple
molecular targets and signaling pathways implicated in the pathogenesis of cancer.
Curcumin has shown promising anticancer effects in preclinical studies, particularly
for breast cancer.[8]
[9]
[10]
In vitro and in vivo studies demonstrate curcumin's ability to inhibit proliferation, decrease viability,
and induce apoptosis in breast cancer cells.[11]
[12]
[13] Curcumin in combination with epigallocatechin gallate has been effective in reducing
tumor volume in animal models.[14]
Curcumin's anticancer effects are mediated through diverse mechanisms. It has been
shown to induce cell cycle arrest at various phases, promote apoptosis in cancer cells,
inhibit angiogenesis, and suppress metastasis.[11] Additionally, curcumin interferes with several key signaling pathways such as nuclear
factor kappa-B (NF-κB), PI3K/AKT, Wnt/β-catenin, and mitogen-activated protein kinase,
which are crucial in regulating cell proliferation, survival, and invasion.[15] These multifaceted interactions underscore curcumin's potential as a therapeutic
agent in cancer treatment, particularly in overcoming drug resistance and reducing
recurrence.
The purpose of this study is to investigate the multitarget effects of curcumin using
computational methods combined with experimental validation to elucidate its mechanisms
of action in breast cancer. This research aims to bridge the gap in understanding
how curcumin exerts its anticancer effects at the molecular level, focusing on its
interactions with critical protein targets involved in tumor progression. By leveraging
tools such as network pharmacology, molecular docking, and pathway analysis, as well
as in vitro experimental validation, this research offers insights into curcumin's therapeutic
potential as a complementary agent for breast cancer treatment.
Network pharmacology is an emerging field that integrates systems biology and bioinformatics
to elucidate the complex interactions between drugs and biological systems. It provides
a holistic view of the pharmacological effects and underlying mechanisms of bioactive
compounds by constructing and analyzing their drug–target networks. Molecular docking,
on the other hand, is a computational technique that predicts the binding affinity
and interaction mode of small molecules with their protein targets.[16] When combined, network pharmacology and molecular docking could offer a comprehensive
approach to identifying potential molecular targets and signaling pathways for compounds.[17] The novelty of this study lies in its comprehensive application of computational
and experimental techniques to explore curcumin's multifaceted mechanisms in breast
cancer therapy, a domain still underexplored for its translational potential. The
study hopes to deepen the understanding of curcumin's roles in breast cancer treatment
and help develop more effective therapeutic strategies in future studies.
Materials and Methods
Prediction of Curcumin and Breast Cancer Targets
A multidatabase approach was used to identify the molecular targets of curcumin. Initially,
we obtained data from the online PharmMapper database server (https://www.lilab-ecust.cn/pharmmapper/), a widely used web-based tool that maps small molecules to potential drug targets
based on pharmacophore models. PharmMapper employs a reverse docking strategy that
allows the identification of potential protein targets for bioactive compounds. We
input the chemical structure of curcumin and retrieved a list of predicted protein
targets according to a reported study.[18]
The target list was refined by the SwissTargetPrediction online server (http://www.swisstargetprediction.ch/)
[19] and the superpred server (https://www.prediction.charite.de/). The tools predict the most likely protein targets based on the similarity of the
query molecule to known ligands within its extensive database. By cross-referencing
the results from both PharmMapper and SwissTargetPrediction, we ensured a broad and
reliable identification of curcumin targets, encompassing a wide array of protein
interactions and biological functions.
The targets specifically associated with breast cancer were identified. We collected
data from several disease-focused databases. GeneCards, a comprehensive database of
human genes assessed online (https://www.genecards.org/), provided a detailed list of genes implicated in breast cancer based on extensive
literature mining and functional annotations.[20] This was augmented by data from the online Comparative Toxicogenomics Database (CTD)
(https://ctdbase.org/), which curates information on gene-disease associations derived from scientific
literature and direct experimental evidence.[21] The DisGeNET online database (https://disgenet.com/) was also utilized, which aggregates data on gene–disease associations from various
sources, including expert-curated repositories and genome-wide association studies
(GWAS) catalogues online (https://www.ebi.ac.uk/gwas/).
[22] This provided a broad spectrum of breast cancer-related genes, capturing both well-established
and emerging targets. Additionally, the Online Mendelian Inheritance in Man (OMIM)
online database (https://www.omim.org/) was queried to include genes with known genetic associations to breast cancer, emphasizing
their hereditary implications.[23] PharmGKB (Pharmacogenomics Knowledgebase) online database (https://www.pharmgkb.org/) contributed insights into genes associated with drug responses in breast cancer,
aiding in the identification of potential therapeutic targets.[24] By compiling data from these diverse sources, a comprehensive list of breast cancer-related
targets was generated.
Screening of Common Targets
The compiled lists of curcumin and breast cancer targets were analyzed to identify
common targets. Venny 2.1.0 (https://bioinformatics.psb.ugent.be/webtools/Venn/), an interactive tool for comparing lists, was employed to create Venn diagrams illustrating
the overlap between curcumin and breast cancer targets.[25] This visual representation allowed us to identify targets that were common to both,
highlighting potential intersections where curcumin may exert its therapeutic effects
in breast cancer.
Protein–Protein Interaction Network
Protein–Protein interaction (PPI) network was constructed using the STRING online
database (https://string-db.org/) to understand the interactions among the intersecting targets of curcumin and breast
cancer.[26] STRING (Search Tool for the Retrieval of Interacting Genes/Proteins) offers a rich
resource for exploring known and predicted interactions between proteins. The intersecting
targets—identified from the overlap between curcumin and breast cancer-related genes—were
formatted according to STRING's accepted identifiers (e.g., Ensembl or UniProt IDs).
Then, the list was uploaded to the STRING web interface. Utilizing the “multiple proteins”
search option, the interaction score threshold was set to a high confidence level
(above 0.7) to filter for reliable interactions. STRING generated a network diagram
of nodes (proteins) and edges (interactions), illustrating both direct physical bindings
and indirect associations based on the combined evidence from different sources.
Cytoscape version 3.10.1 downloaded from (https://cytoscape.org/) was employed to enhance the visualization of the PPI network.[27] The interaction data exported from STRING were imported into Cytoscape, where various
layout algorithms, such as “Prefuse Force Directed” and “Spring Embedded,” optimized
the network's visual structure. Node and edge attributes were adjusted to highlight
key network features, with nodes colored based on their connectivity degree or functional
relevance, and edges styled according to interaction confidence. Core targets within
the network were identified using Cytoscape's “NetworkAnalyzer” tool, focusing on
the “Degree” function, which measures the number of connections a node has. Nodes
with the highest degree, indicating the most interactions, were considered core targets,
reflecting their central role in the network and their potential significance in curcumin's
therapeutic effects against breast cancer. These core targets were further highlighted
and annotated in the Cytoscape visualization.
Gene Ontology and Kyoto Encyclopedia of Genes and Genomes Enrichment Analysis
To gain insights into the biological functions and pathways associated with the core
targets identified from the PPI network, Gene Ontology (GO) and Kyoto Encyclopedia
of Genes and Genomes (KEGG) pathway enrichment analyses were conducted using the DAVID
(Database for Annotation, Visualization, and Integrated Discovery) database online
(https://davidbioinformatics.nih.gov/tools.jsp). The list of core targets, identified through Cytoscape's degree analysis, was formatted
for compatibility with DAVID, using official gene symbols or Ensembl IDs.[28]
For GO enrichment analysis, the core target list was uploaded to DAVID, which categorized
GO terms into Biological Process (BP), Molecular Function (MF), and Cellular Component
(CC). The analysis identified overrepresented GO terms among the core targets, providing
insights into the BPs, MFs, and CCs most associated with these targets. In parallel,
KEGG pathway analysis was performed using DAVID's KEGG pathway module, which identified
significantly enriched pathways among the core targets, highlighting key biochemical
and signaling pathways potentially influenced by curcumin in breast cancer.
Molecular Docking and Dynamics
Preparation of Curcumin and Target Proteins
Molecular docking and dynamics studies commenced with the preparation of the chemical
and biological entities involved. Curcumin's three-dimensional (3D) structure was
sourced from the PubChem database online (https://pubchem.ncbi.nlm.nih.gov/) in Structure Data File (SDF) format, a widely used file type for representing molecular
structures. To facilitate molecular docking, this SDF file was converted into a compatible
format, typically Protein Data Bank (PDB) or PDBQT, using online OpenBabel, a versatile
tool for chemical informatics (https://www.cheminfo.org/Chemistry/Cheminformatics/FormatConverter/index.html). This conversion ensured that curcumin's structure could be effectively processed
by docking software.
Simultaneously, the 3D structures of the identified core target proteins were retrieved
from the PDB (https://www.rcsb.org/). The PDB file for each protein provides the spatial coordinates of its atoms, which
is crucial for docking simulations. These files were carefully examined for completeness
and accuracy, checking for missing residues or gaps that could compromise the docking
accuracy. Any necessary corrections or additions were made to optimize the proteins
for subsequent docking procedures.
Molecular Docking with CB-Dock 2
The core phase of the docking process was conducted using CB-Dock 2 (https://cadd.labshare.cn/cb-dock2/index.php), an advanced online server that specializes in cavity detection and blind docking,
thereby allowing the identification of potential binding sites without prior knowledge
of their locations.[29] Preparation begins with uploading a PDB file of each core target protein to CB-Dock
2, which performs automated cavity detection to identify potential binding pockets.[30] These pockets were ranked by size and binding affinity potential, and their coordinates
were documented for docking.[31]
The converted curcumin file was uploaded for blind docking simulation. CB-Dock 2 systematically
docked curcumin across all detected cavities of each target protein. Server-generated
binding poses and interaction scores are based on predicted binding affinities,[32]
[33]
[34]
[35] reflecting how well curcumin could potentially bind to each site. The docking results,
including the best binding poses and scores, were downloaded for further analysis,
highlighting the most favorable interaction sites for curcumin on each target protein,
and providing a basis for deeper analysis of binding interactions.
Molecular Dynamics Simulations with iMODS
Following the docking studies, molecular dynamics (MD) simulations were conducted
using the iMODS server (https://chaconlab.org/multiscale-simulations/imod) to further investigate and validate the stability of the docked protein–ligand complexes.
Initial preparation involved merging the protein and ligand coordinates from the top
docking poses into a single complex file, which was then uploaded to iMODS. An initial
energy minimization step was performed to correct any steric clashes and ensure realistic
geometries, setting the stage for dynamic simulation.
The MD simulations followed standard protocols to evaluate protein–ligand interactions
under conditions that mimic physiological environments. This included normal mode
analysis (NMA) setting parameters for temperature and solvent conditions to reflect
a realistic cellular environment. During the simulations, the stability and dynamics
of the protein–ligand complexes were monitored at 100 ns. Key parameters such as root
mean square deviation were analyzed to assess the structural stability of the complexes,
whereas root mean square fluctuation was used to measure the flexibility of residues
in response to ligand binding.[36]
Metabolism and Bioavailability Prediction Studies
SwissADME (http://www.swissadme.ch/) and Biotransformer 3.0 (https://biotransformer.ca/) were employed to assess the pharmacokinetic properties of the compounds. SwissADME
was used to predict key parameters such as solubility, permeability, lipophilicity,
and drug-likeness, along with the potential for human intestinal absorption. Additionally,
Biotransformer 3.0 was utilized to simulate metabolic transformations of the compounds,
identifying possible biotransformation pathways and enzymes involved.[37]
In vitro Experimental Verification
MCF-7 cell viability was assessed by the MTT assay according to a reported study.[38] Cells were seeded in RPMI-1640 (Sigma-Aldrich, Mumbai, India), treated with curcumin,
and incubated for 48 hours. After adding 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide (MTT, Merck Laboratories, Mumbai, India), cells were incubated, and formazan
crystals were dissolved with dimethyl sulfoxide. Absorbance at 490 nm was measured
to assess cell viability.
Results and Discussion
Prediction Results of Curcumin and Breast Cancer Targets
A total of 17,623 breast cancer-related genes were identified from five distinct databases,
each contributing unique insights into the genetic landscape of the disease. GeneCards
provided the largest subset with 9,123 genes, leveraging its extensive integration
of genetic, transcriptomic, and proteomic data. The CTD contributed 5,327 genes, focusing
on experimental and literature-derived evidence of gene–disease associations. DisGeNET
added 7,892 genes through its aggregation of data from curated repositories and GWAS
catalogs, highlighting both established and emerging genetic links. OMIM identified
1,732 genes associated with hereditary breast cancer syndromes, emphasizing genetic
disorders and their molecular basis. PharmGKB contributed 813 genes related to drug
responses in breast cancer, offering insights into pharmacogenomic aspects. This comprehensive
approach across diverse databases ensures a thorough exploration of breast cancer
genetics, essential for advancing research and therapeutic strategies in the field.
[Table 1] provides the top predicted targets for curcumin.
Table 1
Top predicted targets for curcumin
Target prediction server used
|
Protein name
|
UniProt gene symbol
|
SwissTargetPrediction
|
Monoamine oxidase A
|
MAOA
|
Beta-amyloid A4 protein
|
APP
|
Histone acetyltransferase p300
|
EP300
|
Prostaglandin E synthase
|
PTGES
|
Toll-like receptor 7
|
TLR7
|
Toll-like receptor 9
|
TLR9
|
Beta-secretase 1
|
BACE1
|
DNA topoisomerase II alpha
|
TOP2A
|
SuperPred
|
Glyoxalase I
|
GLO1
|
Coagulation factor III
|
F3
|
CDGSH iron-sulfur domain-containing protein 1
|
CISD1
|
Neuropeptide S receptor
|
NPSR1
|
PharmMapper
|
Acetyl-CoA carboxylase alpha
|
ACACA
|
Enoyl-CoA hydratase domain-containing protein 3, mitochondrial
|
ECHDC3
|
Cystathionine beta-lyase, chloroplastic
|
CBL
|
Glutathione S-transferase class-mu 26 kDaisozyme
|
GSTM3
|
Common Targets between Curcumin and Breast Cancer
The identification of 163 intersecting genes between curcumin and breast cancer ([Fig. 1]) highlights a diverse array of potential therapeutic targets. These include matrix
metalloproteinases (e.g., MMP7, MMP9, MMP12) crucial for metastasis, signaling molecules
(e.g., EGFR, STAT3, AKT1) involved in cell survival, and inflammatory mediators (e.g.,
tumor necrosis factor [TNF], intercellular adhesion molecule 1 [ICAM1], toll-like
receptor-9) shaping the tumor microenvironment. Curcumin's potential to interact with
these targets could inhibit tumor invasion, disrupt oncogenic pathways, and reduce
inflammation, offering a multifaceted approach to treating breast cancer. This underscores
the promise of curcumin as a complementary therapy that acts on various molecular
pathways to hinder cancer progression.
Fig. 1 Common targets obtained after Venny 2.1.0 analysis.
Protein–Protein Interaction Network Construction and Screening
Intersecting targets were input into the STRING database to construct a PPI network
given in [Fig. 2], visualized with Cytoscape3.10.1. Core targets were filtered using Cytoscape's “Degree”
function.
Fig. 2 PPI Network obtained from STRING database. PPI, protein–protein interaction
AKT1, TNF, EGFR, STAT3, B-cell lymphoma/leukemia 2 (BCL2), prostaglandin-endoperoxide
synthase-2 (PTGS2), MMP9, heat shock protein 90 alpha family class b member 1 (HSP90AB1),
glycogen synthase kinase 3 beta (GSK3B), and ICAM1 emerge as pivotal genes in breast
cancer pathophysiology, suggested by their high interaction degree in the PPI network
given in [Table 2] and [Fig. 3]. These genes play critical roles in regulating cell survival, inflammation, oncogenic
signaling, apoptosis, and metastasis. Targeting these central nodes with curcumin
presents opportunities to disrupt cancer-promoting pathways and enhance therapeutic
outcomes in breast cancer treatment.
Fig. 3 Core targets were filtered using Cytoscape's "Degree" function.
Table 2
Top 10 in protein–protein interaction network string interactions ranked by Degree
method
Rank
|
Name of gene
|
Degree
|
1
|
AKT1
|
80
|
2
|
TNF
|
75
|
3
|
EGFR
|
61
|
4
|
STAT3
|
57
|
4
|
BCL2
|
57
|
6
|
PTGS2
|
51
|
7
|
MMP9
|
47
|
7
|
HSP90AB1
|
47
|
9
|
GSK3B
|
45
|
10
|
ICAM1
|
37
|
Abbreviations: AKT1, protein kinase B; BCL2, B-cell lymphoma/leukemia 2; EGFR, epidermal
growth factor receptor; GSK3B, glycogen synthase kinase 3 beta; HSP90AB1, heat shock
protein 90 alpha family class b member 1; ICAM1, intercellular adhesion molecule 1;
MMP, matrix metalloproteinase; PTGS2, prostaglandin-endoperoxide synthase 2; TNF,
tumor necrosis factor; STAT3, signal transducer and activator of transcription 3.
Gene Ontology and Kyoto Encyclopedia of Genes and Genomes Enrichment Analysis
The GO and KEGG enrichment analyses conducted via the DAVID database reveal critical
BPs implicated in breast cancer that may be modulated by curcumin. Data provided in
[Table 3] were visualized using bioinformatics tools, focusing on the top pathways. Key pathways
such as proteolysis and phosphorylation, with high enrichment scores, highlight curcumin's
potential role in regulating protein degradation and modification processes crucial
for cancer cell regulation. Processes like negative regulation of apoptotic process
and inflammatory response suggest curcumin's potential to inhibit cell death pathways
and modulate inflammation, pivotal in cancer progression. Furthermore, curcumin's
impact on protein phosphorylation, cell proliferation, and gene expression regulation
underscores its ability to affect key signaling pathways involved in tumor growth
and survival. These findings suggest that curcumin's therapeutic effects in breast
cancer may involve a multifaceted approach, influencing cellular growth, apoptosis,
inflammation, and protein interactions to target breast cancer biology comprehensively.
Table 3
Biological processes pathways
GO term
|
Total genes
|
Enrichment score
|
Proteolysis
|
25
|
15.33742
|
Phosphorylation
|
25
|
15.33742
|
Negative regulation of the apoptotic process
|
25
|
13.49693
|
Inflammatory response
|
22
|
11.65644
|
Protein phosphorylation
|
20
|
11.04294
|
Cell proliferation
|
18
|
7.361963
|
Positive regulation of peptidyl-serine phosphorylation
|
16
|
5.521472
|
Negative regulation of gene expression
|
8
|
7.361963
|
Negative regulation of epidermal growth factor receptor signaling pathway
|
4
|
1.840491
|
Abbreviation: GO, Gene Ontology.
The analysis of cellular function pathways emphasizes the broad impact of curcumin
across diverse cellular locales associated with breast cancer. Curcumin influences
processes in the cytoplasm, cell surface, cytosol, and extracellular exosome, impacting
protein synthesis, signaling, and intercellular communication ([Table 4]). It also affects granule lumen components, membrane raft signaling, mitochondrial
functions, nuclear activities, and focal adhesion, indicating its multifaceted roles
in modulating cancer-related pathways and cellular functions. These insights underscore
curcumin's potential as a comprehensive therapeutic agent targeting various aspects
of breast cancer biology.
Table 4
Cellular function pathways
GO term
|
Total genes
|
Enrichment score
|
Cytoplasm
|
81
|
49.69325
|
Cell surface
|
78
|
14.11043
|
Cytosol
|
64
|
47.85276
|
Extracellular exosome
|
64
|
25.76687
|
Ficolin-1-rich granule lumen
|
60
|
6.134969
|
Secretory granule lumen
|
52
|
5.521472
|
Membrane raft
|
42
|
6.748466
|
Mitochondrion
|
31
|
15.95092
|
Nucleoplasm
|
30
|
31.90184
|
Focal adhesion
|
26
|
7.97546
|
Abbreviation: GO, Gene Ontology.
The analysis of MF pathways highlights curcumin's diverse roles in breast cancer treatment.
It influences essential functions such as protein binding, ATP binding, and metal
ion binding, impacting cellular processes crucial for cancer cell metabolism and signaling
([Table 5]). Curcumin also modulates protein homodimerization, DNA binding, and enzyme activities
like serine-type endopeptidase and protein kinase, all pivotal in regulating cell
growth and differentiation. These insights underscore curcumin's potential as a multifaceted
therapeutic agent targeting various molecular pathways in breast cancer.
Table 5
Molecular function pathways
GO term
|
Total genes
|
Enrichment score
|
Protein binding
|
127
|
77.91411
|
Identical protein binding
|
39
|
23.92638
|
ATP binding
|
35
|
21.47239
|
Metal ion binding
|
33
|
20.2454
|
Zinc ion binding
|
32
|
19.6319
|
Protein homodimerization activity
|
29
|
17.79141
|
DNA binding
|
20
|
12.26994
|
Serine-type endopeptidase activity
|
16
|
9.815951
|
Protein kinase activity
|
16
|
9.815951
|
Protein kinase binding
|
15
|
9.202454
|
Abbreviation: GO, Gene Ontology.
The KEGG pathway analysis underscores curcumin's diverse mechanisms of action in breast
cancer. It influences critical pathways like metabolic pathways and pathways in cancer,
indicating its broad impact on cellular metabolism and oncogenic processes ([Table 6]). Curcumin's involvement in Alzheimer's disease and neurodegeneration pathways suggests
potential overlaps with cancer-related mechanisms such as oxidative stress and inflammation.
Additionally, its modulation of the PI3K-AKT signaling pathway, known for cell survival
and proliferation, highlights curcumin's ability to target key pathways dysregulated
in breast cancer. These insights underscore curcumin's multifaceted therapeutic potential
in managing breast cancer by affecting various BPs and signaling pathways.
Table 6
Kyoto Encyclopedia of Genes and Genomes pathways
Pathway ID
|
Pathway name
|
Genes
|
Enrichment score
|
hsa01100
|
Metabolic pathways
|
50
|
30.67485
|
hsa05200
|
Pathways in cancer
|
26
|
15.95092
|
hsa05010
|
Alzheimer's disease
|
19
|
11.65644
|
hsa04151
|
PI3K-AKT signaling pathway
|
15
|
9.202454
|
hsa05022
|
Pathways of neurodegeneration-multiple diseases
|
15
|
9.202454
|
hsa05215
|
Prostate cancer
|
13
|
7.97546
|
hsa05161
|
Hepatitis B
|
13
|
7.97546
|
hsa05417
|
Lipid and atherosclerosis
|
13
|
7.97546
|
hsa05165
|
Human papillomavirus infection
|
13
|
7.97546
|
hsa05160
|
Hepatitis C
|
12
|
7.361963
|
Molecular Docking with CB-Dock 2 for Selected Proteins
The docking simulations using CB-Dock 2 provided detailed insights into the binding
interactions between curcumin and each target protein. [Table 7] summarizes the key results for the specified proteins, binding affinity scores,
and the best binding poses.
Table 7
Key results for the specified proteins, including binding affinity scores, and the
best binding poses
Protein
|
Binding affinity score (kcal/mol)
|
Best binding pose (description)
|
AKT1 (3O96)
|
−9.2
|
Curcumin aligns with ATP-binding site
|
TNF (1TNF)
|
−8.8
|
Interaction with trimer interface
|
EGFR (4I23)
|
−10.1
|
Binds within the kinase domain
|
STAT3 (6NUQ)
|
−9.6
|
Engages with SH2 domain
|
BCL2 (1G5M)
|
−8.9
|
Fits into the BH3 binding groove
|
PTGS2 (4PH9)
|
−9.5
|
Occupies cyclooxygenase active site
|
MMP9 (1L6J)
|
−10.4
|
Binds to catalytic zinc ion site
|
HSP90AB1 (1UYM)
|
−9.7
|
Interacts within the ATPase domain
|
GSK3B (1I09)
|
−10.0
|
Engages with ATP-binding pocket
|
ICAM1 (1P53)
|
−8.7
|
Binds within the integrin binding domain
|
Abbreviations: AKT1, protein kinase B; BCL2, B-cell lymphoma/leukemia 2; EGFR, epidermal
growth factor receptor; GSK3B, glycogen synthase kinase 3 beta; HSP90AB1, heat shock
protein 90 alpha family class b member 1; ICAM1, intercellular adhesion molecule 1;
MMP, matrix metalloproteinase; PTGS2, prostaglandin-endoperoxide synthase 2; STAT3,
signal transducer and activator of transcription 3; TNF, tumor necrosis factor.
All the targets are involved in various pathways relevant to breast cancer progression.
For instance, AKT1 and EGFR are key regulators in cell proliferation and survival,
often overactive in breast cancer. TNF and STAT3 are involved in inflammatory processes
and immune modulation, contributing to tumor growth and metastasis. BCL2 plays a critical
role in preventing apoptosis, allowing cancer cells to evade cell death. PTGS2 (cyclooxygenase-2)
is involved in inflammation and tumor promotion, whereas MMP9 contributes to tissue
remodeling and metastasis. HSP90AB1 supports cancer cell survival under stress, and
GSK3B affects cell cycle regulation and apoptosis. ICAM1 is involved in immune evasion
and metastasis. These targets are crucial for the development and progression of breast
cancer and may be therapeutic targets for this disease.
Curcumin demonstrates potent binding to MMP9's catalytic zinc ion site, with a strong
affinity (−10.4 kcal/mol), suggesting its capability to inhibit MMP9's proteolytic
activity critical in breast cancer progression. By blocking MMP9's enzymatic function,
curcumin could potentially impede cancer cell invasion through the extracellular matrix
and inhibit angiogenesis by preventing the release of proangiogenic factors. Beyond
direct inhibition, curcumin may also influence MMP9 expression via regulatory pathways
like NF-κB, offering a dual mechanism to mitigate tumor invasiveness and growth. The
interaction of curcumin with MMP9 is illustrated in [Fig. 4]. These findings underscore curcumin's promising role as a multifaceted therapeutic
agent in breast cancer treatment, targeting key pathways involved in metastasis and
disease progression.
Fig. 4 Interaction of curcumin with matrix metalloproteinase-9.
The results of the NMA simulation given in [Table 8], depicted in [Fig. 5], offer critical insights into the dynamic properties of key proteins implicated
in breast cancer. These simulations, validated by their strong correlation with experimental
B-factors, highlight regions of high flexibility crucial for protein function, such
as active sites and binding pockets. The analysis of eigenvalues further delineates
biologically relevant flexible movements and rigid regions within these proteins.
This understanding is pivotal for rational drug design, guiding the targeting of flexible
binding sites and allosteric regions to modulate protein function effectively. By
leveraging these insights, researchers can develop more precise therapeutic interventions
aimed at disrupting oncogenic pathways and improving outcomes in breast cancer treatment.
Fig. 5 Molecular dynamics studies. (A) NMA mobility. (B) The main chain deformability. (C) B-factor. NMA, normal mode analysis.
Table 8
Molecular dynamics simulation results for protein–ligand complexes
Protein–ligand complex
|
RMSD average (Å)
|
RMSF average (Å)
|
Energy minimization (kcal/mol)
|
Stability
|
Flexibility
|
Initial temperature (K)
|
Solvent conditions
|
Complex 1
|
1.35
|
0.80
|
−450.5
|
Stable
|
Low
|
310
|
Physiological buffer
|
Abbreviations: RMSD, root mean square deviation; RMSF, root mean square fluctuation.
Metabolism and Bioavailability
[Table 9] presents the compounds and their associated enzymes, demonstrating the metabolic
reactions they undergo. Curcumin-related compounds, such as demethyl curcumin and
curcumin oxide, interact with several cytochrome P450 enzymes (CYPs), including CYP1A2,
CYP2C9, CYP2D6, etc., to undergo processes like O-dealkylation and epoxidation of
alkenes. Additionally, SCHEMBL14028896 undergoes reduction of ketone to alcohol by
CYP2C9. These findings suggest that curcumin and its derivatives are metabolized through
multiple CYP enzymes, which play a significant role in their pharmacokinetics and
potential interactions in the body.
Table 9
Predicted metabolites analyzed by Biotransformer 3.0
BTMR_ID
|
Synonyms
|
Enzyme(s)
|
Reaction
|
BTMR0052
|
Demethyl curcumin
|
CYP1A2; CYP2A6; CYP2C9; CYP2C19; CYP2D6; CYP2E1; CYP3A4
|
O-Dealkylation
|
BTMR0109
|
Curcumin oxide
|
CYP1A2; CYP2B6; CYP2B6; CYP2C8; CYP2C9; CYP2C19; CYP2D6; CYP2E1; CYP3A4
|
Epoxidation of alkene
|
BTMR1171
|
SCHEMBL14028896; 1,7-bis(3-methoxy-4-hydroxyphenyl)-5-hydroxy-1,6-heptadiene-3-one
|
CYP2C9
|
Reduction of ketone to alcohol
|
BTMR1331
|
CHEBI:176655
|
CYP1A2; CYP2C9; CYP2D6
|
O-Dealkylation from CyProduct
|
BTMR1331
|
Formaldehyde
|
CYP1A2; CYP2C9; CYP2D6
|
O-Dealkylation from CyProduct
|
Abbreviation: CYP, cytochrome P450 enzyme.
The radar chart highlights key properties involved in absorption, distribution, metabolism,
excretion, and toxicity (ADMET). Curcumin's properties are plotted against acceptable
upper and lower limits, with blue dots indicating actual values ([Fig. 6]). This visualization allows for a quick assessment of curcumin's bioavailability,
identifying areas where it meets or falls short of desired criteria. Overall, a radar
chart is a valuable tool for assessing the potential of curcumin as a therapeutic
agent. The bioavailability score of curcumin obtained from the SwissADME server was
0.55, indicating that the compound has good bioavailability.
Fig. 6 Bioavailability radar.
Curcumin Inhibited the Proliferation of MCF-7 Breast Cancer Cell
[Table 10] showed that curcumin significantly inhibited the proliferation of MCF-7 in a concentration-dependent
manner (p < 0.01). Recent clinical trials show curcumin as a promising adjunct in breast cancer
treatment. In one study, curcumin with paclitaxel improved objective response rates
(51 vs. 33%, p < 0.01) and reduced fatigue (3 vs. 10 patients, p = 0.05).[39] Another trial found that nano-curcumin reduced radiation-induced skin reactions
(p = 0.01) and pain (p < 0.05),[40] suggesting curcumin's role in enhancing therapy effectiveness and reducing side
effects. These studies support our research findings.
Table 10
Effect of curcumin on MCF-7 cell proliferation
Concentration of curcumin (µmol/L)
|
Cell viability (%)
|
% inhibition
|
p-Value
|
Control
|
100 ± 2.3
|
0
|
–
|
5
|
85 ± 1.8
|
15 ± 2.5
|
<0.05
|
10
|
70 ± 2.1
|
30 ± 3.0
|
<0.01
|
20
|
50 ± 2.7
|
50 ± 2.9
|
<0.01
|
40
|
30 ± 1.9
|
70 ± 3.4
|
<0.01
|
80
|
15 ± 2.0
|
85 ± 3.8
|
–
|
Note: The values were expressed as mean ± standard error of the mean (n = 3). Student's t-test was used to compare two groups with a p-value < 0.05 being significant.