]
Bladder tumors originate from the urothelium,
which is the epithelial layer covering the inner surface
of the bladder at a rate of 90%, and at the time of diagnosis,
75% of the cases have non-muscle-invasive
BC (NMIBC) limited to the mucosa.[,] On the other
hand, 10-20% of cases with NMIBC generally progress
to a poor prognosis, muscle-invasive BC (MIBC) with a
5-year survival rate of 60% for cases with local tumors,
and 10% for metastatic cases.[] Higher survival rates
can be achieved in NMIBCs with transurethral resection of the bladder tumor (TUR-BT); however, disease recurrence
often presents as a more aggressive tumor in the
first 5 years.[] All this information reveals the necessity
of regular follow-up of patients with BC, especially
after TUR-BT. Cystoscopic imaging is still using as the
gold-standard method for the diagnosis and follow-up
of BC.[] Cystoscopes are optical instruments that allow
visualization of the inside of the bladder by entering
from the urethra, and they can also perform tissue
sampling with biopsy forceps. However, since imaging
with a cystoscope is an invasive procedure, the search for
a low-cost and reliable biomarker with high sensitivity
and specificity that can be used in the diagnosis and follow-
up of patients with BC is still ongoing. However, the
recent epigenetic studies are suggested to provide successful
results for BC. Therefore, in this study, we review
that the DNA methylation and microRNA relationship
with BC were investigated in the light of current studies
in the literature, particularly using the meta-analyses.
BC and DNA Methylation
The most known and most studied of epigenetic studies
are DNA methylation. DNA methylation describes
the formation of 5-methylcytosine with the addition of
methyl group (-CH3) to the carbon atom of the 5th position
of the cytosine base. The basis of the regulation
of gene expression of DNA methylation is due to the
frequent methylation of CpG islands which are intensively
detected in the promoter regions of the genes. In
almost all cancer types including BC, the genes behaving
as tumor suppressors have gene expression suppression
due to hypermethylation on their promoters. However,
the CpG islands associated with the promoters of genes
whose expressions are always required to be active such
as housekeeping genes are in unmethylated condition.[]
Many studies are evaluating the DNA methylation
changes in BC. Bai et al.[] investigated the APC gene
promoter methylation in a sample of 2214 BC patients,
and 665 healthy controls in their wide meta-analysis,
and reported that methylation in samples with cancer
was significantly increased (p<0.01) compared with the
methylation in healthy tissues, and urine samples. They
suggested with these data that APC gene promoter
methylation might be associated with the progression
of BC and suggested that should be evaluated as a noninvasive
biomarker that could be analyzed from urine
samples.[] The RASSF1A gene promoter methylation
was investigated in a sample of 1588 BC patients, and
720 healthy controls and methylation were found to
have significantly increased in BC patients (p<0.0001)
in a wide meta-analysis conducted by Zhan et al.[] Researchers confirmed their results with the methylation
analysis results obtained from The Cancer Genome Atlas
(TCGA) because there was a mismatch between the
age, sex, and smoking habits of the samples included in
the meta-analyses, and for eliminating the bias due to
differences in methods used in all studies.
Therefore, they compared in accordance with the
control groups and stages and revealed to show a positive
correlation with their meta-analysis results by evaluating
selectively the RASSF1A gene promoter methylation
among the global methylation data studies from
BC samples on TCGA. Study results showed that the
RASSF1A gene promoter methylation in Stage III and
Stage IV bladder tumors were statistically significantly
increased (p<0.0001) compared with tumors in Stage
I, and Stage II tumors in accordance with the TNM
classification in addition to the comparison with the
healthy samples. From this point of view, researchers
suggested that RASSF1A gene might be used as a clinical
biomarker in the diagnosis of BC because there was
a significant association between BC, and RASSF1A
gene promoter methylation.[] Dai et al.[] stated in
their meta-analysis which evaluated the DAPK promoter
methylation and BC association that there was
a statistically significant association (p<0.00001) between
the BC development risk and DAPK promoter
methylation in their evaluation with 1247 BC patients,
and 405 healthy controls. Researchers suggested at the
end of the study that DAPK promoter methylation was
not associated with tumor stage (p<0.668), however,
might be associated with higher tumor stage (p<0.011).
Chen et al.[] investigated the promoter methylation
of the CDH13 gene in their meta-analysis in a
sample consisting of 1017 BC patients, and 265 healthy
controls. Researchers reported at the end of the study
that there was a statistically significant (p<0.001) association
between CDH13 gene promoter methylation, and
BC development in both tumor tissue and urine sample
level. In addition, researchers reported that CDH13 gene
promoter methylation level was higher among Asians
compared with the levels among Caucasians (p<0.001),
and methylation status showed no difference in accordance
with sex (p=0.053). They suggested that CDH13
gene promoter methylation might be used as a prognostic
biomarker because a significant association was
detected between the increased CDH13 gene promoter
methylation and high-grade bladder tumors (p<0.001),
muscle-invasive bladder tumors (p<0.001), and multifocal
bladder tumors (p=0.032). In addition to the association
of a single gene methylation status with BC, Yu et
al.[] in their wide meta-analysis and systematic review evaluated whether DNA methylation had a prognostic
significance for BC, and investigated the DNA methylation-
based studies conducted between years 2000 and
2018. After their meta-analysis study, they confirmed
that the increased DNA methylation status showed a
positive correlation with poor prognosis, and DNA
methylation studies had prognostic importance for BC.
The data of TCGA are highly important in bioinformatics-
based cancer research. Yang et al.[] analyzed
the data involving 540 different methylated genes
obtained from TCGA, and the methylation status of
seven consisting of MIR6732, SOWAHC, SERPINI1,
OR10W1, OR7G3, AIM1, and ZFAND5 had independently
prognostic importance for BC after conducting
two variable and single variable Cox regression analyses.
Interestingly, the SOWACH gene methylation and
the mRNA expression level of the gene showed a negative
correlation among these genes; however, SOWACH
gene methylation and expression showed a positive
correlation with prognosis. In another study, Zhang
et al.[] evaluated the microarray data expressing the
genes which were included in the Gene Expression Omnibus
database, and which showed abnormal methylation
and expression in BC using various bioinformatics
tools. The obtained candidate genes after the analysis
were compared with the data obtained from TCGA
and were confirmed. At the end of the study, the genes
CDH1, DDOST, CASP8, DHX15, and PTPRF were
mainly overexpressed, and were hypomethylated; however,
all the genes as GNG4, ADCY9, NPY, ADRA2B,
and PENK were hypermethylated, and their expressions
were mainly decreased. Researchers suggested that
these ten genes might be the biomarkers in the evaluation
of the diagnosis, treatment, and prognosis of BC.
Bosschieter et al.[] analyzed the methylation status
of protein-coding genes of CADM1, FAM19A4,
GHSR, MAL, PHACTR3, PRDM14, SST, and ZIC1, and
miRNA genes of miR-124-2, miR-129, miR-137, miR-
148, miR-181, and miR-935 in the urine samples of 72 BC
patients, and 75 healthy controls using the quantitative
MS-PCR. No significant difference was detected except
the methylation condition of the CADM1, miR-124-2,
miR-137, and miR-181 genes; however, the methylation
status of the remaining ten genes was reported to show
an increase and a significant difference in BC patients
compared with the control group. Researchers found
that GHSR and MAL genes could successfully differentiate
specifically the urine samples of BC, and healthy
individuals with 92% sensitivity and 85% specificity in
their analysis by creating a panel with the genes statistically
significantly strongest among these ten genes.
Then, researchers analyzed the tissue-based methylation
status of GHSR, and MAL genes, and showed a
significant increase in tumor tissues, and suggested that
the methylation analysis of these two genes might be
used as a panel that will enable noninvasive diagnosis
from urine for BC. Stubendorff et al.[] evaluated the
association of metastasis and lymph node involvement
with DNA methylation in MIBC patients in their study.
They analyzed the global DNA methylation status in 23
muscle-invasive bladder tumor tissues in the scope of
the study in a microarray-based analysis. In addition,
they supported their studies by analyzing the protein
and mRNA expression levels in wider patient samples,
and by performing functional analyses in T24 and
253JB-V cell lines. They reported that the methylation
analysis of the panel consisting of 3 genes as KISS1R,
SEPT9, and CSAD might be a strong prognostic indicator
that could differentiate the positivity or negativity
of lymph node involvement in MIBC patients. Leão et
al.[] evaluated the TERT promoter mutation prevalence,
and TERT Hypermethylated oncologic region
(THOR) methylation in their study conducted with
237 bladder tumor tissue, and 94 healthy bladder tissues.
They stated that THOR hypermethylation is a risk
factor for NMIBC due to its increase of TERT expression,
and the altogether analysis of TERT promoter
mutation and THOR hypermethylation could provide
statistically significant information about recurrence
(p<0.0001), and progression (p=0.025).
Guo et al.[] emphasized that one of the most significant
symptoms of BC of hematuria was among the
primary causes of presenting to the clinic, however,
was mostly idiopathic, and with a different perspective
aimed to identify malignity in the case of hematuria
by investigating the promoter methylation of ten
candidate genes involving the ABCC6, BRCA1, CDH1,
GDF15, HSPA2, RASSF1A, SALL3, THBS1, TMEFF2,
and VIM genes from the urine samples of 217 patients
with urothelial carcinoma in the upper urinary system,
and urothelial BC with hematuria, and from the samples
of 256 healthy controls using the MS-PCR. The analysis
of the promoter methylation of eight genes of VIM,
CDH1, SALL3, TMEFF2, RASSF1A, BRCA1, GDF15,
and ABCC6 out of ten candidate genes could differentiate
the presence of urothelial carcinoma in hematuric
patients with 83% sensitivity, and 60% specificity and the
panel consisting of the genes CDH1, HSPA2, RASSF1A,
TMEFF2, VIM, and GDF15 could differentiate upper
urinary tract urothelial carcinoma from other groups
with 82% sensitivity and 68%, and the panel consisting
of the genes VIM, RASSF1A, GDF15, and TMEFF2 could differentiate urothelial BC from other groups with 82%
sensitivity, and 53% specificity. In addition, researchers
indicated that the panel consisting of CDH1, SALL3,
THBS1, TMEFF2, VIM, and GDF15 genes showed a
higher success for detecting malignity in patients with
hematuria in the accompany with urine cytologic analysis.
van Kessel et al.[] prospectively included 1239
NMIBC patients (276 are low risk, 273 are moderate risk,
and 555 are high risk of tumor progression) into their
multicenter study with the participation of researchers
from 6 European countries by emphasizing that the
European Urology Association recommended the performing
of pathologic parameters-based risk classification
in the guidelines for NMIBC which constitute more
than 70% of bladder tumors. Researchers investigated
the methylation status of GATA2, TBX2, TBX3, and
ZIC4 genes, and the mutation status of FGFR3, TERT,
PIK3CA, and RAS genes in the fresh frozen tumor tissues
of patients. 54 patients were found to show progression
toward MIBC, among all genes the mutation status
of FGFR3 gene and methylation of GATA2 and TBX3
genes were shown to be significantly associated with the
disease progression, and researchers indicated that these
genes might be a risk factor that could be used in the
estimation of progression in NMIBC patients. Shindo et
al.[] in their two centers prospective study, included
132 NMIBC patients initially, and taken urine samples,
and followed up these patients, and analyzed the methylation
status of miR-9-3, miR-124-2, miR-124-3, and
miR-137 genes in all samples compatible with the study
criteria by taking repeat urine sample in recurrent cases
using the bisulfite pyrosequencing. Researchers investigated
the association between the methylation status in
these miRNA genes, and recurrence, and revealed that
urine-based methylation analysis conducted using this
miRNA gene panel might be an indicator for the decision
of recurrence and radical cystectomy in BC. López
et al.[] performed genome-wide methylation analysis
in different stages and grades 70 bladder tumors, and ten
healthy tissue samples and the tumor tissues of 43 genes
reported to have hypermethylation higher than 10%.
Researchers found that the JAK3 gene hypermethylation
and nonmethylation of EYA4, GAT6, and SOZ1
genes were associated with low-grade non-invasive
bladder tumors. However, the hypermethylation of the
genes CSPG2, HOXA11, HOXA9, HS3ST2, SOX1, and
TWIST1 was found associated with muscle invasion.
Researchers reported that the hypermethylation of the
genes APC, CSPG2, EPHA5, EYA4, HOX9, IPF1, ISL1,
JAK3, PITX2, SOX1, and JAK3 might be used in the estimation
of cancer-associated survival, and the hypermethylation
of SOX1, PITX2, or CSPG2 genes was significantly
associated with BC associated mortality risk.
The evaluation of the response to Bacillus Calmette-
Guérin (BCG) immunotherapy which is an important
treatment modality in NMIBC patients is highly important
in the decision of further treatment options in later
stages. Husek et al.[] investigated the DNA methylation
status of tumor suppressor genes in response to
BCG immunotherapy in their study. Researchers included
82 NMIBC patients with high grades in their
study and divided patients into two groups as successful
or unsuccessful in accordance with the response to
BCG immunotherapy. Analyses associated with methylation
changes were performed using the commercial
ME001 (MRC-Holland Inc.) and ME004 (MRC-Holland
Inc.) MS-MLPA kit which includes probe set for
various tumors suppressor genes using the paraffin-embedded
tumor tissues of patient groups, and 13 healthy
bladder tissues. Researchers showed in the study that
the methylation status of tumor suppressor CDKN2b,
MUS81a, PFM-1, MSH6, and THBS1 genes was significantly
associated with immunotherapy response, and
methylation of CDN2b and MUS81a genes was statistically
significantly associated with (p=0.0312, p=0.0191)
successful response to BCG immunotherapy, however,
showed that CDN2b and MUS81a genes were not
methylated in the patient group who responded unsuccessfully
to BCG immunotherapy.
Although smoking is a primary risk factor in BC,
patients were divided into subgroups and evaluated in
accordance with their smoking habits in a very limited
part of studies in the literature. The interaction of epigenetic
factors with the environment is a well-known
fact, however particularly in DNA methylation, it is
clear that smoking will create a significant variation for
BC development, and progression between individuals.
The first clinical and in vitro study evaluating this issue
was performed by Jin et al.[] Researchers analyzed
the significant changes in the tissue samples and urine
sample metabolomes of 78 smokers and 41 nonsmoker
BC patients using the LC-MS, and evaluated the obtained
data with bioinformatics tools, and confirmed
with the cell lines and TCGA data. Significantly higher
methylated metabolites, polycyclic aromatic carbons,
deteriorated nucleotides/adducts in DNA, and genetic
changes showing the DNA damage were detected in
the smoker BC patient group compared with the nonsmoker
group. These data explain the detection of the
higher number of advanced-stage tumors in the presence
of smoking at the molecular level. Researchers also
reported that DNMT1 enzyme (and therefore smoking induced DNA methylation) was increased in smoker
BC patients, and the aniline level which is important
in bladder carcinogenesis, and SAM level directly associated
with DNA methylation were found significantly
higher in the smoker group; however, the S-Adenocyl-
L-Homosistein level was significantly decreased.[]
Epidemiologic studies showed that the prevalence
of BC was lower among Afro-Americans compared
with other people in the same region, and this difference
was interpreted as that BC prevalence might be
lower in the black race. Vantaku et al.[] suggested
that this was stemmed from DNA methylation-associated
epigenetic changes, and they analyzed the DNA
methylation patterns of Afro-American BC patients,
and Euro-American BC patients using bisulfite sequencing,
and using LC-MS/MS for metabolomes, and
compared the values. In addition to the metabolomic
differences, the study results showed that the CpG islands
of the promoters of xenobiotic enzymes known
as important in BC progression were more commonly
hypermethylated in Afro-Americans compared with
the Euro-Americans. Researchers revealed at the end
of the study that the race and ethnicity differences in
the molecular biology of BC might create prognostic
variations over DNA methylation.
BC and MicroRNAs
MicroRNAs are short and noncoding RNA molecules
with a length of 18-28 bp whose target molecules are
mRNAs. MicroRNAs represent a very small portion of
the total RNA despite taking more than half of all genes
in their targets. In addition, the interaction ability of
a single microRNA with multiple mRNAs increases
the functionality of these molecules. MicroRNAs are
exposed to a complex maturation period in the nucleus,
and molecules in the form of pre-miRNA are
transferred to ultimate miRNA form in the cytoplasm
through molecular exportin mediated transfer. MicroRNAs
are commonly suggested to suppress the
transcription by binding to 3"-UTR regions of mRNAs;
however, conducted studies showed that they might
increase the transcription.[,] Considering all
these features, the suppression of oncogene-associated
miRNAs with anti-miRNAs (antagomir) or strategies
such as stimulation of the tumor-suppressing genes as
an option in cancer treatment has come to agenda for
increasing the chemoradiotherapy sensitivity.[]
One of the most comprehensive studies on the importance
of miRNAs in BC is the meta-analysis conducted
by Xie et al.[] The researchers collected and
filtered all studies conducted between 2009 and 2016
from different databases, and investigated 37 miRNAs which were reported to have prognostic importance in
the sample consisting of 2753 BC patients, and in different
stages. The meta-analysis showed that 6 miRNAs
consisting of miR-21, miR-143, miR-153, miR-200,
miR-214, and miR-222 were found to have been commonly
repeated in most studies. They reported that
miR-21 and miR-222 expressions showed correlation
with shortened general survival, and increased miR-
143 and miR-155 expression were associated with
shortened nonprogressive survival and decreased
miR-214 expression was associated with shortened
recurrence-free survival and stated that this miRNA
panel might be evaluated as the useful biomarkers and
therapeutic targets in the follow up of BC patients.[]
Chen et al.[] investigated in another meta-analysis
the association of miRNA levels in kidney, bladder,
and prostate urologic cancers with survival estimation.
Researchers investigated 80 different miRNAs in
151 data set after collecting and filtering all miRNAbased
studies conducted for three urologic cancer
types in different databases until the end of 2017 and
confirmed their results with the TCGA data. The
changes in miR-21, miR-34a, miR-141, and miR-203
were commonly observed for each 3 urologic cancer
types however after TCGA confirmation only miR-
21 showed statistically higher significantly (p<0.001)
shortened general survival. In addition, miR-21 was
found associated with poor prognosis in BC independent
of other cancers. Researchers indicated that the
evaluation of miRNA based indicators as panels would
have higher success rates compared with their single
evaluation, and showed that the panel in kidney cancer
consisting of miR-27a, miR-27b, miR-141, miR-144,
miR-497, and miR-942 could estimate a statistically
significant general survival (p<0.001) compared with
each miRNA in the panel. Yang et al.[] investigated
how the single miR-15a affected the general survival
in 18 different cancer types in their meta-analysis, and
gathered all studies performed until the end of 2018,
and included 1616 cancer patients in ten articles to
their study after filtering. The decreased miR-15a expression
was found associated with statistically significantly
shortened general survival (for BC, p=0.0081)
in 8 cancer types including BC in the meta-analysis,
and researchers suggested that miR-15a might be used
as a biomarker in the estimation of general survival.
Although miRNA panels in different combinations
may have different sensitivity, and specificity rates for
survival estimation, in a general sense the question of
whether miRNAs could be used for BC diagnosis is
an important question. In their meta-analysis, Shi et
al.[] included ten articles in their studies after filtering
and investigated the diagnostic importance of miRNAs in a sample consisting of 1556 BC patients and
1347 healthy controls. Researchers reported after the
meta-analysis that miRNA profiling from blood could
show high success in BC diagnosis however, ethnic
differences might cause significant variations even in
the same sample subgroups. Researchers also revealed
that miRNA profiling particularly from blood in Asian
population-based studies showed higher accuracy for
BC diagnosis however, more studies were required
for exact results. Xiao et al.[] in their more detailed
meta-analysis included 22 articles after filtering and
investigated whether the quantitative RT-PCR based
miRNA profiling performed from blood, and urine
in the samples of 4558 BC patients, and 4556 healthy
controls might be used as a noninvasive biomarker for
BC diagnosis. Researchers concluded that the blood
and urine-based miRNA analysis could differentiate
BC patients from healthy controls with 74% sensitivity
and 78% specificity, and could detect the early period
BC, blood-based analyses alone showed higher performance
compared with the urine-based analyses, the use
of miRNAs as panels increased the performance, and
miRNA profiling in Caucasians showed lower success
in BC diagnosis compared with the Asian populations.
In their meta-analysis, Ouyang et al.[] investigated
the diagnostic value of miRNA profiling in kidney,
bladder, and prostate urologic cancers, and included 39
articles in their study after filtering. The general sensitivity
and specificity of miRNA profiling in the diagnosis
were found as 74%, and 72%, respectively for three
urologic cancer types. In the independent analysis
conducted for BC, miRNA profiling in a general sense
could differentiate BC samples from healthy controls
with 74% sensitivity and 74% specificity; the sensitivity
reached 79%, and specificity to 73% in Asians in the
analysis considering the ethnical differences, and sensitivity
levels were detected as 71%, and specificity as 71%
in Caucasians. The diagnostic value of miRNA profiling
was also investigated in the blood, and nonblood
samples in BC, and 77% sensitivity, and 74% specificity
were found in blood-based miRNA profiling; however,
74% sensitivity and 72% specificity level was obtained
in nonblood samples. Researchers also revealed that
73% sensitivity and 71% specificity level were detected
in the use of single miRNA in BC diagnosis, and the use
of miRNA panel increased the level of diagnostic sensitivity
and specificity to 83%.[] There is a consensus
on the preference of miRNA panels for differentiative
diagnosis of BC for survival estimation for increasing
the performance; however, it was emphasized that the
investigation of the effect of the use of single miRNAs
for BC progression, treatment response, or tumor behavior
is another topic that should be evaluated.
Conducted studies showed that the expressional
changes of miRNAs also had huge roles on the key genes
included in the two pathway hypothesis in addition to
the role of mutations. To exemplify, the miRNA-99a and
miR-100 are known to have roles in the regulation of the
FGFR3 gene products, the increased miR-143 resulted
in the decrease in the RAS gene expression; miR-125b,
miR-143, miR-30a/c, and miR-223 directly targeted the
TP53 gene, and miR-10, and miR-129 caused an indirect
change in the regulation of TP53 gene by targeting
the MDM2, MDM4, and ATM genes.[] In this regard,
the miRNA profiling in the early stage BC might change
the treatment modalities by rapidly distinguishing the
MIBC or NMIBC differentiation, and might emerge
strong therapeutic targets. The gene product enzyme of
METTL3 is suggested to have a role in all stages starting
from their being transcribed on RNAs and affected
the tumor development by regulating the N6-Methyladenosine
(m6A) modification on the mRNAs of critical
oncogenes, and tumor suppressors, and specifically
caused the BC progression through m6A dependent
AFF4/NF-κB/MYC signal pathway.[,] Based on
this data, Han et al.[34] investigated how the METTL3
affected the m6A modification in noncoding RNAs such
as miRNA in the concept of BC and used the EJ and T24
MK cell lines in addition to tumor tissues and healthy
tissues adjacent to tumor in BC patients in their study.
Study results showed that METTL3 had an expressional
increase correlated with poor prognosis in BC. Researchers
also suggested that METTL3 accelerated the
pri-miR-221 and pri-miR-222 maturation through an
m6A dependent pathway, and this was useful in decreasing
PTEN expression which is significantly responsible
for the progression of BC cells and suggested its use in
BC treatment. In another study, Lu et al.[] evaluated
the effect of a noncoding circular RNA of circSLC8A1
in BC progression and used the cell lines consisting of
5637, T24, J82, EJ, UMUC, RT4, and SV-HUC-1 in addition
to tumor tissue and healthy tissues in the adjacent
to tumor in BC patients. Researchers revealed that circSLC8A1
expression significantly decreased in cancerous
cell lines, and particularly in tumor tissues, and this
decrease showed a positive correlation with tumor stage
and grade. In addition, they showed that circSLC8A1
suppressed the BC progression by inhibiting the expression
increase of PTEN expression of these miRNAs by
directly interacting with miR-130b, and miR-494. Hou
et al.[] evaluated the effect of miR-127 on BC progression
in their study. First, the researchers showed with
the bioinformatics analysis that miR-127 targeted the
KMT2D, and investigated this data using the NMIBC
tissue of 20 patients, and MIBC tissues of 20 patients,
and the cell lines consisting of RT4, T24, UMUC-3, 5637, EJ, and SV-HUC-1. Study results showed that the
miR-127 expression was found higher in MIBC tissues
compared with the expression in NMIBC tissues, and in
addition, an increase in BC cell lines was detected compared
with the level in healthy cell lines. The silencing of
miR-127 expression significantly decreased the viability
and migration in T24, and UMUC-3 cells. In addition,
researchers stated that KMT2D was associated with a
good prognosis by demonstrating that KMT2D which
has a role in all genome transcription of miR-217 primarily
the H3K4me1, increased its expression.
Lin et al.[] used the tissue samples, and T24, RT4,
5637, HT-1376, J82, UMUC-3, and TCCSUP cell lines
of 164 BC patients, and investigated whether miR-325
might be a potential biomarker for BC. Study results
showed that the expression of the miR-325 in tumor
tissues, and cancerous cell lines were statistically significantly
decreased compared with the level in healthy
tissues and cell lines (p<0.05), and miR-325 expression
was found associated with statistically significantly
decreased (p=0.0114) postoperative general survival.
In addition, the researchers showed that miR-325 was
found to show tumor suppressor features with the decrease
of cisplatin chemoresistance with tumor proliferation
and migration in vitro experiments by overexpression
through lentiviral transfection in T24, and 5637
cell lines; however, in vivo experiments the transplant
growth and GO/G1 transition in cells were statistically
significantly delayed in the group where the miR-325
was overexpressed in T24 and 5637 cells subcutaneously
implanted to athymic-nude nu/nu mice appropriate for
transplantation. Tian et al.[] used the T24, J82, and
SV-HUC-1 cell lines in addition to tumor tissues and
healthy bladder tissue in the adjacent to tumor obtained
from 50 BC patients in their study which investigated
the effect of miR-621 in progression in BC. Researchers
showed that miR-621 expression level in tumor tissues
with T24 and J82 cell lines was statistically significantly
highly decreased compared with the healthy tissues and
noncancerous SV-HUC-1 cell line (p<0.01), and this
decrease was correlated with the tumor progression. In
addition, the miR-621 expression level was shown to
have a negative correlation with general survival. Researchers
indicated that miR-621 directly targeted the
3"-UTR region of TRIM29. In addition, TRIM29 level
was statistically significantly increased in tumor tissues
compared with the levels in healthy tissues, and
TRIM29 and miR-621 showed a completely reverse directional
expressional change is statistically higher significance
level in tumor tissues (p<0.001). In addition,
miR-621 was suggested to inhibit the proliferation and
metastasis through the Wnt/Β-catenin signal pathway
in BC cells by targeting the TRIM29.
Feng et al.[] evaluated the miRNA-99a change
and its prognostic importance in BC in the tumor tissues,
and healthy bladders tissues adjacent to tumor
obtained from 100 BC patients; in the plasma samples
obtained from 50 BC patients, and 50 healthy controls,
and in J82, HT1376, RT4, T24, TCCSUP, HCV29, and
HU609 cell lines. Study results showed that the expression
level of miR-99a was found statistically significantly
lower in tumor tissues, in cancerous cell lines,
and the plasma samples of BC patients (p<0.01). The
decreased miR-99a level was found correlated with the
aggressive BC phenotype, and researchers showed that
proliferation was correlated with aggressive BC phenotype,
and proliferation in cell lines which overexpressed
the miR-99a was inhibited. Wu et al.[] evaluated the
change of miR-379-5p, and their prognostic importance
in BC in tumor tissue, and healthy bladder tissues
obtained from 27 BC patients, and in T24, EJ, TCCSUP,
and SV-HUC-1 cell lines in their study. Bioinformatics
analyses showed that miR-379-5p directly targeted
the 3"-UTR region of MDM2; therefore, MDM2 was
also included in the study. Study results showed that
miR-379-5p expression levels statistically significantly
(p<0.05) decreased in tumor tissues, and T24, J82, and
TCCSUP BC cell lines compared with the expression
in healthy tissues, and noncancerous SV-HUC-1 cell
line; however, the expression level of MDM2 was increased
in cancer tissues. Researchers found that cell
proliferation was inhibited, and invasion and metastasis
capacity was statistically significantly decreased in T24,
and EJ cancerous cell lines where the miR-379-5p was
overexpressed through transfection (p<0.05), and they
found similar results when they suppressed the MDM2
expression in the same cell lines through siRNA. Jiang
et al.[] investigated the effect of miR-93, and PEDF
which targets from its 3"-UTR region on the BC proliferation,
and invasion in the tumor tissues of 30 BC
patients, and healthy bladder tissue in the adjacent to
tumor in TCCSUP, 5637, UMUC-3, and T24 cell lines.
MiR-93 expression was found to have statistically significantly
increased in tumor tissues compared with
the expression in healthy tissues (p<0.05) and showed
a correlation with tumor stage, and with the presence of
lymph node metastasis. Researchers suppressed the expression
of miR-93 in TCCSUP and UMUC-3 cell lines
where the miR-93 expression was the highest among all
cell lines and showed that cell proliferation and invasion
were statistically significantly (p<0.05) decreased.
In addition, they also revealed that miR-93 expression
was decreased in cell lines where the PEDF was overexpressed,
and cell proliferation and invasion were statistically
significantly decreased (p<0.05).
