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South Russian
Journal of Cancer..
Vol. 5
No. 3, 2024
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South Russian
Journal of Cancer..
Vol. 5
No. 3, 2024
South Russian Journal of Cancer. 2024. Vol. 5, No. 3. P. 91-101
https://doi.org/10.37748/2686-9039-2024-5-3-8
https://elibrary.ru/avxoui
ORIGINAL ARTICLE
Metabolomic profile of malignant ovarian tumors
F. E. Filippov2, D. S. Kutilin1 , A. Yu. Maksimov1, N. V. Porkhanova2
1 National Medical Research Centre for Oncology, Rostov-on-Don, Russian Federation
2 Clinical Oncology Dispensary No. 1, Krasnodar, Russian Federation
k.denees@yandex.ru
ABSTRACT
Purpose of the study. Investigate the metabolomic profile in tissues of patients with serous ovarian adenocarcinoma.
Materials and methods. The study included 100 patients with serous ovarian adenocarcinoma. Chromatographic separation of
metabolites was performed on a Vanquish Flex UHPLC System
chromatograph,
which was coupled with an Orbitrap Exploris
480 mass spectrometer. Differences were assessed using the Mann-Whitney test with Bonferroni correction.
Results. In ovarian tumor tissue, 20 compounds had abnormal concentrations compared to normal tissue: increased levels of
kynurenine, phenylalanylvaline, lysophosphatidylcholine (18:3), lysophosphatidylcholine (18:2), alanylleucine, L-phenylalanine,
phosphatidylinositol (34:1), 5-methoxytryptophan, lysophosphatidylcholine (14:0), indoleacrylic acid and decreased levels of
myristic acid, decanoylcarnitine, aspartylglycine, malonylcarnitine, 3-methylxanthine, 3-oxododecanoic acid, 2-hydroxymyristic
acid, N-acetylproline, L-octanoylcarnitine and capryloylglycine.
Conclusion. A
significant metabolic
imbalance was found in ovarian tumor
tissue,
expressed in abnormal concentrations
of fatty acids and their derivatives, acylcarnitines, amino acids and their derivatives, phospholipids and nitrogenous base
derivatives. The concentrations of these 20 metabolites in tissues can serve as diagnostic markers of ovarian cancer. Thus,
metabolomic tissue profiling allowed both to identify potential markers
of the disease and to better understand the molecular
mechanisms of changes underlying the development of this disease.
Keywords: metabolites, ultra-high performance liquid chromatography and mass spectrometry, ovarian serous
adenocarcinoma, biomarkers
For citation: Filippov F. E., Kutilin D. S., Maksimov A. Yu., Porkhanova N. V. Metabolomic profile of malignant ovarian tumors. South Russian Journal of
Cancer. 2024; 5(3): 91-101. https://doi.org/10.37748/2686-9039-2024-5-3-8, https://elibrary.ru/avxoui
For correspondence: Denis S. Kutilin � PhD in Biology, Leading Researcher, Laboratory of Molecular Oncology, National Medical Research Centre for
Oncology, Rostov-on-Don, Russian Federation
Address: 63 14 line str., Rostov-on-Don 344037, Russian Federation
E-mail: k.denees@yandex.ru
ORCID: https://orcid.org/0000-0002-8942-3733
SPIN: 8382-4460, AuthorID: 794680
Scopus Author ID: 55328886800
Compliance with ethical standards: the research study is carried out in compliance with the ethical principles set forth by World Medical Association
Declaration of Helsinki, 1964, ed. 2013. The study was approved by the Committee on Biomedical Ethics at the National Medical Research Center for
Oncology (extract from the minutes of the meeting No. 17 dated 06/28/2022). Informed consent was received from all participants of the study
Funding: this work was not funded. The work was performed with scientific equipment provided by the Central Research Institute of the National Medical
Research Center for Oncology: https://ckp-rf.ru/catalog/ckp/3554742/
Conflict of interest: the authors declare that there are no obvious and potential conflicts of interest associated with the publication of this article
The article was submitted 21.07.2024; approved after reviewing 27.08.2024; accepted for publication 29.08.2024
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INTRODUCTION
In the last decade, among oncogynecological
diseases, ovarian cancer has occupied leading positions
in terms of morbidity and mortality in the
world and Russia [1, 2]. Malignant ovarian tumors
are divided into many histological subtypes, each of
which has distinctive biological and clinical characteristics.
There are serous carcinoma, endometrioid
carcinoma, mucinous carcinoma, light cell carcinoma,
malignant Brenner tumor, serous-mucinous
carcinoma, undifferentiated carcinoma and mixed
epithelial carcinoma. Serous adenocarcinoma is
the most common subtype [3, 4].
The overall five-year survival rate of ovarian cancer
patients does not exceed 40 %, which is due to
late diagnosis. To date, the sensitivity and specificity
of the main diagnostic methods of this disease
are insufficient to detect it at an early stage [5, 6].
New approaches are needed to improve diagnosis.
Metabolomics methods based on high-resolution
liquid chromatography and mass spectrometry
(MS) open up new prospects for the detection and
identification of biomarkers in the femtomolar and
attomolar ranges.
So in the work of Y. Ahmed-Salim and co-authors
analyzed the results of 32
publications in the field
of metabolic research in ovarian cancer. Most studies
have reported a violation of the regulation of
phospholipids and amino acids: histidine, citrulline,
alanine and methionine. At the same time, combinations
of more than one metabolite as a panel
in various studies achieved higher sensitivity and
specificity for diagnosis than a single metabolite;
for example, combinations of various phospholipids
[7].
In [8], the role of histidine and citrulline in the
development of ovarian cancer was confirmed,
and new lipid compounds (lysophosphatidylcholine
C16:1, phosphatidylcholine C32:2, C34:4
and
C36:6) potentially involved in cancer metabolism
were discovered.
However, such studies in ovarian cancer are not
numerous compared to genomic and transcriptomic
ones, and most of them were performed on
equipment with lower resolution and a principle of
operation different from Orbitrap technology [9],
and biological fluids of patients, such as urine [10]
or blood [11].
The purpose of the study was to study the metabolic
profile of tissues of patients with serous ovarian
adenocarcinoma in order to identify potential
diagnostic markers of the disease.
MATERIALS AND METHODS
The study included 100 patients diagnosed with
serous ovarian adenocarcinoma (T3a-c). Samples
of normal and tumor tissue obtained at the stage
of surgical treatment were used as objects of research.
The average age of the patients was 54.2
years.
Analysis of metabolites by the
HPLC-MS method
Surgical biopsies of tumor and normal ovarian
tissue were used for analysis, which were stored in
liquid nitrogen until the moment of metabolic and
molecular genetic studies. The samples were homogenized
at a temperature no higher than 4
�C.
The homogenate was mixed with 600 .l of acetonitrile
LC-MS (Merck, Germany)/methanol LC-MS
(Merck, Germany) in a ratio of 3/1, was stirred for 15
minutes using a vortex and incubated for 15 hours
at �20
�C. Proteins were precipitated by centrifugation
at 16000
g 0 �C for 30
minutes. The supernatant
was transferred to clean Eppendorf tubes. The
solvent was evaporated at 45
�C for 4
hours on a
SpeedVac vacuum evaporator (Eppendorf). The resulting
dry precipitate was dissolved in 300 .l of 95
% acetonitrile LC-MS solution (Merck, Germany) with
the addition of 0.1 % formic acid (Merck, Germany).
To better dissolve the sediment, the samples were
treated with ultrasound in an Elmsonic P 120
H ultrasonic
bath (ELMA, Germany). Further, the samples
were centrifuged for 30 min at 16000 g and the
resulting supernatant was used for chromatomass
spectrometric analysis.
Chromatographic separation of metabolites was
performed on a Vanquish Flex UHPLC System Thermo
Fisher Scientific chromatograph. The chromatograph
was paired with the Orbitrap Exploris 480
mass spectrometer, which has an electrospray ionization
source. A sample of metabolites in a volume
of 2 .l was divided on a Hypersil GOLD� C18 column
(1.9
.m, 150
. 2.1
mm), eluents: A � 0.1
% formic
acid LC-MS (Merck, Germany), B � acetonitrile
LC-MS (Merck, Germany) containing 0.1 % formic
South Russian Journal of Cancer 2024. Vol. 5, No. 3. P. 91-101
Filippov F. E., Kutilin D. S. , Maksimov A. Yu., Porkhanova N. V. Metabolomic profile of malignant ovarian tumors
acid (Merck, Germany). The following elution gradient
was used: 1
min � 5
% of eluent B, 15 min � linear
gradient of eluent B from 5 to 95 %, 2 min � 95 %
of eluent B, 0.5 min � change of eluent composition
to 5 % of eluent B, 3 min � 5
% of eluent B. The flow
of eluents is 200 .l/min.
Mass spectrometric analysis was performed on
an Orbitrap Exploris 480 (Thermo Fisher Scientific)
mass spectrometer with an electrospray ionization
source. The mass spectrometer was configured
for priority ion detection in the m/z range from 67
to 1000 Da with a resolution of 60,000. The spectra
were taken in the detection mode of positively
charged ions. The time to remove one spectrum is
20 minutes. Additional MS settings were as follows:
ion sputtering voltage = �3.5 kV; capillary temperature
= 320 �C; sample heater temperature = 300 �C;
protective gas = 35; auxiliary gas = 10
and radio frequency
S-lens � 50.
For mass spectrometric peaks to be identified,
compliance with specific metabolites from the
Human Metabolome Database was established
(http://www.hmdb.ca) and Metlin (Scripps Center
for Mass Spectrometry, USA; http://metlin.scripps.
edu). For this purpose, an accurately measured
mass of the chemical compound was used. Bioinformatic
analysis was performed using Compound
Discoverer Software (Thermo Fisher Scientific,
USA) and analysis of biochemical pathways using
the KEGG PATHWAY Database.
Statistical data processing
The differences were assessed using the
Mann-Whitney criterion for a threshold level of statistical
significance of p < 0.05, and the Bonferroni
correction was used to account for multiple comparisons.
The data analysis was carried out in the
Python programming language using the SciPy library
[12].
STUDY RESULTS
During the conducted metabolomic
profiling,
100
samples of serous ovarian adenocarcinoma and 100
samples of conditionally normal ovarian tissues were
analyzed. 750 metabolites were identified. For
metabolites
whose intensities in the mass spectra differed
statistically significantly relative to
normal tissue,
P-value and FoldChange were determined (Table 1).
According to the data obtained, the metabolome
of the tumor tissue of patients with serous ovarian
carcinoma differed significantly from samples
of normal ovarian tissue of the same patients. In
the tumor tissue of the patients, 10 metabolites
(kynurenine, phenylalanyl valine, lysophosphatidylcholine
(18:3), lysophosphatidylcholine (18:2), alanyl
leucine, L-phenylalanine, phosphatidylinositol
(34:1), 5-methoxytryptophan, lysophosphatidylcholine
(14:0), indolacrylic acid) had significantly higher
concentrations In comparison with conditionally
normal tissue, the concentration of 10 compounds
(myristic acid, decanoyl carnitine, aspartyl-glycine,
malonylcarnitine, 3-methylxanthine, 3-oxododecanoic
acid, 2-hydroxymyristinic acid, N-acetylproline,
L-octanoylcarnitine, caprylylglycine), on the contrary,
was reduced.
Thus, it was found that the concentrations of
myristic acid, 2-hydroxymyristic acid and 3-oxododecanoic
acid in tumor tissue were statistically significantly
(p < 0.01) reduced by 2.6
times, 4.8
times
and 1.4 times, respectively, compared with normal
tissue. The levels of decanoyl carnitine, malonylcarnitine
and L-octanoyl carnitine in tumor tissue
were statistically significantly (p < 0.0001) lower
by 5.3 times, 1.5 times and 6.7 times, respectively,
than in normal tissue. Statistically significantly
(p < 0.00000005), the concentration of a number of
phospholipids in tumor tissue in patients with ovarian
cancer was increased relative to normal ovarian
tissue: lysophosphatidylcholine (18:3) by 2.1 times,
lysophosphatidylcholine (18:2) by 3.4
times, phosphatidylinositol
(34:1) by 4.1
times and lysophosphatidylcholine
(14:0) by 1.9
times. Statistically
significant (p < 0.01) changes in the concentration
of some amino acids and their derivatives were
also found: an increase in the concentration of
kynurenine by 6.1 times, phenylalanyl valine by
2.2 times, alanyl leucine by 1.6
times, L-phenylalanine
by 1.8 times, 5-methoxytryptophan by 1.6 times
and indolacrylic acid by 1.5 times relative to normal
tissue, as well as a decrease in the concentration
of N-acetylproline by 1.7 times, caprylylglycine by
1.5 times and aspartyl glycine by 5.0 times, respectively,
relative to normal ovarian tissue. A change in
the content of nitrogenous base derivatives in ovarian
tumor tissue was also detected, i.e. a 2.3-fold
decrease in the concentration of 3-methylxanthine
(p < 0.0001).
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DISCUSSION
The HPLC-MS method identified 750
metabolites
of various classes, while the concentration of
10 metabolites in the tumor tissue was significantly
increased compared to conditionally normal tissue,
and the concentration of 10 compounds was lowered
on the contrary.
Fatty acids and their derivatives
In the tumor tissue, the concentrations of most
fatty acid derivatives � myristic acid, 2-hydroxy
myristic acid and 3-oxododecanoic acid were reduced
compared to conditionally normal tissue.
Tumor cells are characterized by a profound restructuring
of the metabolism of lipids and fatty acids. In
some types of tumors, the utilization of fatty acids
increases, while in others it is suppressed [13, 14].
Myristic acid (CH3(CH2 COOH, FoldChange 0.38,
)12
p = 0.0000241)
is
a saturated fatty acid with
an
aliphatic long chain, present in almost all living or
ganisms
[15]. Abnormal
levels
of myristic acid can
increase the risk of tumors
[16]. It
is
involved in
the
implementation of several antitumor mechanisms,
Table 1. The difference between the metabolomic profile of tumor tissue and normal in patients with serous ovarian
adenocarcinoma
Metabolites m/z FoldChange,
tumor/normal tissue p-value
1. Fatty acids and their derivatives
Myristic acid 231.2 0.38 0.00002410
2-hydroxymyristic acid 267.2 0.21 0.00001000
3-oxododecanoic acid 237.1 0.74 0.01000060
2. Acylcarnitines
Decanoyl carnitine 316.2 0.19 0.000000003
Malonyl carnitine 230.1 0.65 0.000100002
L-octanoylcarnitine 288.2 0.15 0.000004011
3. Phospholipids
Lysophosphatidylcholine (18:3)
518.3 2.05 0.000000002
Lysophosphatidylcholine (18:2)
521.3 3.40 0.000000051
Lysophosphatidylcholine (14:0)
468.3 1.89 0.000000003
������������������ (34:1)
430.8 4.11 0.000000001
4. Aminoacids and their derivatives
Alanine-Leucine 185.1 1.55 0.000900000
Phenylalanine-Valine 265.2 2.15 0.000100000
L-Phenylalanine 166.1 1.84 0.000000002
Kinurenin 209.1 6.07 0.000001000
Aspartyl-glycine 208.1 0.20 0.000012400
5-methoxytryptophan 217.1 1.61 0.000004200
Indolylacrylic acid 171.1 1.49 0.010189400
N-acetylproline 140.1 0.59 0.000085630
Capriloyl glycine 202.1 0.65 0.010212890
5. Derivatives of nitrogenous bases
3-methylxanthine 167.1 0.44 0.000100000
South Russian Journal of Cancer 2024. Vol. 5, No. 3. P. 91-101
Filippov F. E., Kutilin D. S. , Maksimov A. Yu., Porkhanova N. V. Metabolomic profile of malignant ovarian tumors
such as the production of myristoleic acid, which
causes apoptosis, and in the synthesis of ceramides
de novo. According to a number of authors, the con
tent
of myristic acid in
biological
fluids
and tissues
is inversely associated with the risk of colorectal
cancer. However, the mechanisms underlying this
relationship have
not
been
fully studied [17-20].
2-hydroxymyristic acid O3, FoldChange
(C14H28
0.21, p = 0.00001) is a fatty acid containing an aliphatic
chain carrying a hydroxyl substituent at position
2, is a derivative of myristic acid. The physiological
function of hydroxy fatty acids remains
largely unknown. They have been shown to play a
specific role in signaling to cells [21]. 2-Hydroxymyristinic
acid is metabolically activated in cells to
form 2-hydroxymyristoyl-CoA, a potent inhibitor of
myristoyl-CoA [22]. Currently, the main mechanisms
by which 2-hydroxylation of fatty acids is associated
with metabolic adaptation and tumor growth re
main unclear [23].
3-oxododecanoic acid (C12 O3, FC = 0.74,
H22
p = 0.01000060) is a fatty acid that is a 3-oxo derivative
of decanoic acid. In the human body, 3-oxododecanoic
acid participates in a number of en
zymatic reactions [24]. Keto-fatty acids are often
reported as artifacts of fatty acid oxidation, but
relatively rarely as natural fatty acids. 3-Keto-fatty
acids, found as secondary components of animal
tissues, are usually intermediates of .-oxidation.
For the beta-oxidation of fatty acids by mitochondria,
the presence of carnitine, an important cofactor
of metabolic processes, is an indispensable
condition. There are more than 1,000 types of acylcarnitines
in the human body, the general function
of which is to transport acyl groups of organic acids
and fatty acids from the cytoplasm to the mitochondria
so that they can be broken down during beta
oxidation to produce energy [25]. This is one of the
most efficient ways of energy production in cells,
therefore, tissues with high energy consumption
mainly depend on the utilization of fatty acids [26].
Cancer is a pathological condition characterized
by high energy consumption. Glucose and glutamine
as energy substrates are considered a distinctive
feature of tumor cells, and the metabolic
switch that allows their use in almost anaerobic
conditions is known as the Warburg effect [27]. The
canonical interpretation of the Warburg effect implies
that cells bypass the mitochondrial respiratory
chain to synthesize ATP even with sufficient oxygen
supply [28]. However, it is obvious that the Warburg
effect needs to be considered in a more general
metabolic context, which also includes the utilization
of fatty acids in accordance with the effectiveness
of these substrates in terms of ATP output.
Metabolic flexibility is a phenomenon observed in
different types of cancer and within the same type
of cancer at different stages of progression. Carnitine-
induced fatty acid oxidation plays a critical
role in the production of NADH, FADN2, NADPH,
and ATP, which can contribute to the development
of tumors [29].
Acylcarnitines
Metabolic reprogramming of tumor cells regulates
the content of acylcarnitines with different
chain lengths in order to create a balance between
production, energy consumption and synthesis of
metabolic intermediates to meet the requirements
of rapid proliferation [30]. Acylcarnitines have cytotoxicity
and immunomodulatory properties that
can be used by the tumor for growth and survival
in situ [31]. Thus, a change in the level of malonylcarnitine
is associated with the risk of developing
breast cancer.
Malonylcarnitine is a metabolite that accumu
lates with a specific violation of fatty acid oxidation
caused by a violation of the intake of long-chain
acylcarnitine esters into the mitochondria and in
sufficiency of the mitochondrial respiratory chain
with a deficiency of complex 11
and malonyl-CoA
decarboxylase [32].
L-octanoylcarnitine is a physiologically active
form of octanoylcarnitine [33], which is found in
deficiency of medium chain acyl-CoA dehydrogenase
(MCAD). L-octanoylcarnitine is involved in lipid
peroxidation (HMDB: HMDB0000791), fatty acid
metabolism (HMDB: HMDB0000791), mitochondrial
beta oxidation of short-chain saturated fatty
acids (HMDB: HMDB0000791) and lipid transport
(HMDB: HMDB0000791). Changes in its concentrations
have been recorded in blood and faeces in
colorectal cancer, Crohn's disease and ulcerative
colitis [34].
Decanoyl carnitine is classified as an acylcarnitine
with a medium chain length. A change in the
concentration of decanoyl carnitine was found in
renal cell carcinoma and breast cancer [35].
����-���������� �������������� ������ 2024. �. 5, � 3. �. 91-101
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The study of fluctuations in the content of acylcarnitines
can contribute to a better understanding
of the mechanisms of oncological diseases and the
development of methods for their diagnosis and
treatment.
Phospholipids
In this study, an increase in the concentration of
lysophosphatidylcholines and phosphatidylinositol
was observed in ovarian tumor tissue. Lysophospholipids
are secreted by various types of cells, including
tumor cells. These chemical compounds play
an important role in the development, activation,
and regulation of the immune system [36]. Changes
in the composition and content of phospholipids
and lysophospholipids have previously been shown
in prostate cancer and are considered as potential
biomarkers [37]. Lysophospholipids function as signaling
molecules through their specific membrane
receptors. In addition, some of the lysophospholipids
have tumor-promoting activity and are therefore
called "oncolipids" [38]. Recent studies have shown
that phospholipids are candidates for PH biomarkers.
Several comprehensive prospective studies of
lipids have been conducted, such as lysophosphatidylcholines,
phosphatidylcholines, ceramides and
sphingomyelins, the concentrations of which differ
in patients with rheumatoid arthritis compared with
healthy ones [39, 10].
Lysophosphatidylcholines, also called lysolecithins,
are a class of chemical compounds formed
from phosphatidylcholines by the enzyme phospholipase
A2. Lysophosphatidylcholines are the most
common phospholipids in the blood and key lipids
in various pathophysiological conditions such as
inflammation, endothelial activation and atherogenesis
[40]. Among other properties, they act as
a signaling molecule released by apoptotic cells to
attract phagocytes, which then phagocytize apoptotic
cells [41].
Phosphatidylinositols are minor phospholipids
of the inner membrane layer of eukaryotic cells,
important components of intracellular signaling
pathways. Phosphatidylinositol is a substrate for
a variety of signaling kinase molecules that can
attach a phosphate group to inositol. The main
biological functions of phosphatidylinositols are
a membrane stabilizer (HMDB: HMDB0009799)
and a molecular messenger (signaling molecule
(HMDB: HMDB0009799)). Phosphatidylinositols
are involved in such important signaling pathways
and processes as fatty acid metabolism
(HMDB: HMDB0009799), lipid peroxidation (HMDB:
HMDB0009799), apoptosis, cell adhesion [42], cell
migration and proliferation [43]. Their content increases
in the blood (HMDB: HMDB0009799) in a
number of oncological diseases, including breast
cancer, colorectal cancer and stomach cancer [44].
Amino acids and their derivatives
An abundant supply of nutrients, such as amino
acids, is necessary for the increased metabolic
needs of tumor cells that maintain high proliferative
activity [45].
The alteration of tryptophan metabolism in cancer
via the kynurenine pathway has attracted widespread
attention as a mechanism by which tumors
can elude immune control [45].
Kynurenine (.-(o-aminobenzene)-.-aminopropio
nic acid) is an intermediate product of the enzymatic
breakdown of tryptophan and the biosynthesis of
nicotinic acid in the human body. During enzymatic
oxidation, kynurenine is converted to 3-hydroxykynurenine.
The pathway of L-tryptophan biotransformation
with the formation of "kynurenine" metabolites
plays an important role in the mechanisms
of immunoregulation and "negative" control of im
mune inflammation [46].
In addition to the main pathways of tryptophan
catabolism, there are secondary ones, one of them
leads to indolylacrylic acid (C11H9NO2, indolacrylate),
the biological role of which in animals is
still unclear [47]. Stimulating the production of indolacrylic
acid can promote anti-inflammatory reactions
and have therapeutic value [47]. In our study,
the level of indolacrylic acid is elevated in ovarian
tumor tissue. The production of indolacrylic acid
may contribute to the development of anti-inflammatory
reactions [47]. It has been shown to selectively
affect breast cancer cells, but does not affect
untransformed primary fibroblasts. In our study, an
increase in indolacrylic acid was accompanied by
an increase in the content of kynurenine.
5-methoxytryptophan (C12 N2O3), which is an en
H14
dothelial factor with anti-inflammatory properties, is
synthesized from L-tryptophan by 2 enzymes: tryptophan
hydroxylase-1 and hydroxyindole-O-methyltransferase
[48]. It controls the migration and acti
South Russian Journal of Cancer 2024. Vol. 5, No. 3. P. 91-101
Filippov F. E., Kutilin D. S. , Maksimov A. Yu., Porkhanova N. V. Metabolomic profile of malignant ovarian tumors
vation of macrophages by inhibiting NF-kB
[49], and
also regulates epithelial-mesenchymal transition
and metastasis [50].
Changes in the metabolism of another aromatic
amino acid, phenylalanine and its derivatives, are
also associated with inflammation and immune activation.
Neurauter G. et al showed that the concentration
of phenylalanine in serum in patients with
ovarian carcinoma correlates with the concentration
of markers of immune activation and the development
of oxidative stress [51].
We also found a decrease in the content of aspartyl
glycine dipeptide in tumor tissue. This compound
is probably a product of incomplete breakdown
of proteins and peptides. It is known that
some dipeptides have physiological or cellular
signaling effects, although most of them are simply
short-lived intermediates on the way to specific
amino acid degradation pathways. Some dipeptides
are also considered as biomarkers of diseases [52].
Concentrations of N-acetyl-L-proline (C7 NO3)
H11
and caprylylglycine also decrease. N-acetylproline
is a biologically available N-terminal form of the proteinogenic
alpha amino acid L-proline. N-terminal
acetylation of proteins is a widespread and highly
conserved process in eukaryotes, which is involved
in the protection and stability of proteins [53]. A
number of studies have shown the association of
N-acetyl-L-proline with colorectal cancer [54] and
metastatic melanoma [55]. Caprylylglycine is a lipid
amino acid consisting of caprylic acid and glycine.
Acylglycines are usually minor metabolites of fatty
acids [55].
Nitrogenous base derivatives and steroids
In our study, a decrease in the concentration
of 3-methylxanthine was found in ovarian tumor
tissue. 3-methylxanthine (C6H6N4O2) is a methyl
derivative of purine with a ketone group (3,7-dihydropurine-
2,6-dione). Some evidence suggests that
methylxanthines have antitumor effect [56]: they inhibit
PI3K/Akt/mTOR and stimulate PTEN, promoting
apoptosis and autophagy [57].
CONCLUSION
A significant change in metabolism was found
in the ovarian tumor tissue, presented in abnormal
concentrations of fatty acids and their derivatives,
acylcarnitines, amino acids and their derivatives,
phospholipids and derivatives of nitrogenous bases.
Concentrations of these metabolites in tissues
can serve as diagnostic markers of ovarian cancer.
Thus, the metabolic profiling of tissues allowed
both to identify potential markers of the disease
and to better understand the molecular mechanisms
of changes underlying the development of
this disease.
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Information about authors:
Fedor E. Filippov � oncologist of the Department of Oncogynecology, Clinical Oncology Dispensary No. 1, Krasnodar, Russian Federation
Denis S. Kutilin � Cand. Sci. (Biol.), Leading Researcher, Laboratory
of Molecular Oncology, National Medical Research Centre for Oncology,
Rostov-on-Don, Russian Federation
ORCID: https://orcid.org/0000-0002-8942-3733, SPIN: 8382-4460, AuthorID: 794680, Scopus Author ID: 55328886800
Aleksey Yu. Maksimov � Dr. Sci. (Med.), Professor, Deputy Director General, National Medical Research Centre for Oncology, Rostov-on-Don,
Russian Federation
ORCID: https://orcid.org/0000-0002-9471-3903, SPIN: 7322-5589, AuthorID: 710705, Scopus Author ID: 56579049500
Natalya V. Porhanova � Dr. Sci. (Med.), Associate Professor of the Department of Oncology, oncologist, Clinical Oncology Dispensary No. 1,
Russian Federation, Krasnodar, Russian Federation
SPIN: 2611-4840, AuthorID: 589928
Contribution of the authors:
Filippov F. E. � conducting the experiment, writing the manuscript;
Kutilin D. S. � concept and design of the study, conducting the experiment, bioinformatics analysis, writing the manuscript;
Maksimov A. Yu. � editing the manuscript;
Porkhanova N. V. � statistical data processing.