Critical thinking about study design on colon cancer

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1. What study design was used? (200 words minimum)

2. How did the study design limit the findings of the article? (100 words minimum)

3. Could a better study design be selected? Why or Why not? (200 words minimum)

4. What other design that can selected that is effective? (200 words minimum)

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Differential MIR-21 Expression in Plasma From Mesenteric
Versus Peripheral Veins

An Observational Study of Disease-free Survival in Surgically Resected Colon
Cancer Patients

z-R

Mariano Monzo, MD, PhD, Francisco Martı́ne

MS
Ra

Abbreviations: CRC = colorectal cancer, CT = computed

tomography, DFS = disease-free survival, miRNA = microRNA,

MV = mesenteric vein, PV = peripheral vein.

circulating miR-21 in C
ing miRNAs from an ar
from a peripheral vein

Editor: Maria Kapritsou.
Received: June 18, 2014; revised and accepted: September 5, 2014.
From the Molecular Oncology and Embryology Laboratory, Human
Anatomy Unit, School of Medicine, University of Barcelona, IDIBAPS,
Barcelona (MM, AN, SS, IM, CM, RT); Department of Medical Oncology
and Surgery, Hospital Municipal de Badalona, Badalona, Spain (FM-R, IM,
RH).
Correspondence: Mariano Monzo, Department of Human Anatomy and

Embryology, School of Medicine, University of Barcelona, Casanovas
143, 08036 Barcelona, Spain (e-mail: [email protected]).

This study was partially supported by a grant from SDCSC (Servei de
Donació del Cos a la Ciència). RT is recipient of an APIF (Ajuts de
Personal Investigador Predoctoral en Formació) grant from the Uni-
versitat de Barcelona. Neither of these funding bodies had a role in the
design and conduct of the study; collection, management, analysis, and
interpretation of the data; preparation, review, or approval of the manu-
script; or decision to submit the manuscript for publication.

The authors have no conflicts of interest to disclose.
Copyright # 2015 Wolters Kluwer Health, Inc. All rights reserved.
This is an open access article distributed under the Creative Commons
Attribution-NonCommercial-NoDerivatives License 4.0, where it is
permissible to download, share and reproduce the work in any medium,
provided it is properly cited. The work cannot be changed in any way or
used commercially.
ISSN: 0025-7974
DOI: 10.1097/MD.0000000000000145

Medicine � Volume 94, Number 1, January 2015

Isabel Moren

Alfons Navarro, PhD, Sandra Santasusagna,

Rut Tejero, PhD, and

Abstract: Findings on the role of plasma miR-21 expression in

colorectal cancer are contradictory. Before reaching a peripheral vein

(PV), microRNAs released by the tumor are dispersed throughout the

body. We hypothesized that blood drawn from the mesenteric vein

(MV) near the site of the primary tumor could provide more homo-

geneous information than blood drawn from the PV.

We have analyzed miR-21 expression in matched samples of tumor

tissue, normal tissue, MV plasma, and PV plasma in 57 surgically

resected patients with colon cancer and correlated our findings with

clinical characteristics and disease-free survival (DFS).

miR-21 expression was higher in MV than PV plasma (P¼ 0.014)

and in tumor than in normal tissue (P< 0.001). Patients with high levels

of miR-21 in MV plasma had shorter DFS (P¼ 0.05) than those with

low levels, and those with high levels in both MV and PV plasma had

shorter DFS than all other patients (P¼ 0.01).

Our findings suggest that the primary tumor in colon cancer releases

high concentrations of miR-21 in the MV but that these concentrations

are later diluted in the circulatory system. MV expression of miR-21

may be a stronger prognostic marker than PV expression.

(Medicine 94(1):e145)

, Ismael Macias, MD, Carmen Muñoz, MS,

odenas, MD, PhD, o, MD, PhD,

quel Hernández, MD

INTRODUCTION

C olorectal cancer (CRC) is the third most common type of
cancer and the second cause of cancer death worldwide.1

The main prognostic factor for relapse and survival in CRC is
disease stage, and patients with stage III disease have a higher
risk of relapse than those with stage II. Surgery is the standard
treatment for stage I to III, and adjuvant treatment has been
shown to be effective in stage III but less so in stage II.2

Prognostic and predictive biomarkers can provide a useful tool
for selecting treatment and improving outcome in these patients.
The analysis of biomarkers in the plasma or serum of CRC
patients is a noninvasive yet effective way to determine prog-
nosis, detect occult tumors, and monitor treatment.

MicroRNAs (miRNAs), noncoding RNAs that play a key
role in the regulation of mRNA expression, are promising
diagnostic and prognostic biomarkers in several cancers.3

Numerous studies have shown that miRNAs are aberrantly
expressed during tumor development and can act either as
oncogenes or tumor suppressors.4,5 The specific mechanism
whereby tumor cells release miRNAs into the blood is not
completely understood. Recent studies have shown that exo-
somes and microvesicles can act as miRNA transporters,6–8

whereas other studies have found that miRNAs circulate freely
in blood by binding to the AGO-2 protein complex, which
prevents the digestion of RNase in plasma.9

miR-21 was the first tumor-related miRNA to be ident-
ified, detected in the serum of a patient with B-cell lymphoma.10

Since then, miR-21 has been widely studied in tumor, plasma,
and serum samples, both in CRC and in other tumors, where it
controls carcinogenesis by targeting different genes, including
TPM1,11 PDCD4,12,13 PTEN,14 and BTG2.15 In hepatocellular
carcinoma16 and non–small-cell lung cancer,17 plasma and
serum levels of miR-21 have been identified as reliable bio-
markers for both diagnosis and prognosis. In addition, post-
operative levels of miR-21 were lower than baseline levels in
both gastric cancer18 and squamous cell carcinoma of the
esophagus.19

In CRC, some studies have identified miR-21 in serum20,21

or plasma22,23 as a useful diagnostic and prognostic biomarker.
However, in other studies, miR-21 expression was not detected
in the peripheral blood of CRC patients, although other miR-
NAs, including miR-17–3- miR-92,24 miR-29a,25 miR92a,26

and miR-221,27 were identified as circulating tumor bio-
markers. These contradictory findings may be due to various
causes, including differences in patient characteristics, internal
controls, and cutoff values. Importantly, all previous studies of

RC have consistently obtained circulat-
ea far from the primary tumor, generally
(PV) located in the forearm. However,

www.md-journal.com | 1

before reaching the PV of the forearm, the miRNAs released
by the tumor are diluted and dispersed in other parts of the
body, which may explain the inconsistency between miRNA
expression levels in the tumor itself and those detected in
peripheral blood.

In CRC, venous return occurs through the superior mesen-
teric vein (MV) if the tumor is located in the right colon, through
the inferior MV if the tumor is located in the left colon, and
through the iliac veins if the tumor is located in the middle or
lower third rectum. Therefore, we can hypothesize that in colon
cancer, blood samples drawn from the MV near the site of the
primary tumor can provide more homogeneous and effective
information than blood drawn from the PV of the forearm. To
test this hypothesis, we have analyzed miR-21 expression in
paired samples of tumor tissue, normal tissue, plasma obtained
by blood drawn from the MV, and plasma obtained by blood
drawn from the PV in 57 surgically resected patients with colon
cancer and correlated our findings with the clinical character-
istics and disease-free survival (DFS) of these patients.

METHODS

Eligibility and Patient Evaluation
From August 2009 to August 2013, samples were obtained

from 57 patients with stage I to IV colon cancer who underwent
surgical resection at the Municipal Hospital of Badalona.
Approval for the study was obtained from the institutional
review board of the hospital, and signed informed consent
was obtained from all patients and controls in accordance with
the Declaration of Helsinki.

All 57 patients underwent a complete history and physical
examination including routine hematological and biochemical
analyses, chest radiographs, and computed tomography (CT) of
the thorax and abdomen. Target lesions detected by abdominal
ultrasound were also assessed by CT or magnetic resonance
imaging.

Samples
For all 57 patients, we obtained tumor tissue, paired normal

tissue, MV blood, and PV blood. Normal tissue was obtained
from the area of the colon farthest from the tumor. Both tumor
and normal tissue samples were analyzed and confirmed by a
pathologist and frozen at �808C for further use.

On the day of surgery, 5 mL of blood was drawn from the
PV and stored in heparinized tubes. During surgery, with
vascular ligation before tumor resection, an additional 5 mL
of blood was drawn from either the superior or the inferior MV,
according to the anatomic location of the tumor. Blood samples
from 18 healthy individuals (young male athletes) were
obtained from the blood bank of the Hospital Clinic for use
as controls. All blood samples were centrifuged at 5000g during
5 min, and plasma was centrifuged at 10,000g during 10 minutes
at 48C to eliminate remaining cells. Plasma samples were frozen
at �808C for further use.

RNA Extraction and miRNA Quantification
Total RNA was extracted from fresh tumor and paired

normal tissue and from PV plasma and paired MV plasma
using miRNeasy Mini Kit (Qiagen, Valencia, CA, USA)
according to the manufacturer’s protocol. miRNA detection

Monzo et al

was performed using commercial assays (TaqMan MicroRNA
assays, Life Technologies, Grand Island, NY, USA) for
miR-21, in the 7500 Sequence Detection System (Life

2 | www.md-journal.com

Technologies). The appropriate negative controls (non-
template control) were also run in each reaction. All reactions
were performed in duplicate. Relative quantification was
calculated using the formula 2�DDCt. Normalization was per-
formed with miR-191.

Statistical Analyses
Differences between �2 groups were calculated using the

Mann–Whitney U test or the Kruskal–Wallis test as appro-
priate. miR-21 expression levels were dichotomized according
to the fixed threshold method using the maxstat package of R to
determine the optimal cutoff that best discriminated between
different groups of patients for DFS. Fifty-two patients were
evaluable for DFS; the 5 stage IV patients in whom only the
primary tumor—but not the metastasis—was removed were not
included in the analysis of DFS. DFS was calculated from the
date of surgery to the date of death, relapse, or last follow-up.
The univariate analysis of DFS was performed with the
Kaplan–Meier method and compared using the log-rank test.
All statistical analyses were performed with SPSS 14.0 (SPSS
Inc, Chicago, IL) and R 2.6.0 Software (Vienna, AU). Statistical
significance was set at P� 0.05.

RESULTS

miR-21 Expression in Plasma and Tissue
Median miR-21 expression (fold change) was 0.2874 in

MV plasma, 0.1805 in PV plasma, and 0.0201 in plasma from
healthy controls. Median miR-21 expression in tumor and
normal tissue was 0.3907 and 0.1733, respectively. miR-21
expression was significantly higher in MV plasma compared
with PV plasma (P¼ 0.005) (Figure 1A). miR-21 expression
was also significantly higher in tumor than in normal tissue
(P< 0.001) (Figure 1A).

Patient Characteristics and miR-21 Expression
Table 1 shows the clinicopathologic characteristics of the

57 patients included in the study. Median age was 70 years.
Thirty-four patients were males and 23 females. At diagnosis,
35 patients were having stage I to II of cancer, 15 stage III, and
7 stage IV. All patients underwent surgical resection; in 2 of
the 7 stage IV patients, both the primary tumor and the meta-
stasis were removed. Twenty-eight patients received adjuvant
therapy with fluoropyrimidines.

MV miR-21 levels correlated positively with tumor size
(P¼ 0.04) and showed a trend toward correlation with carci-
noma embryonic antigen levels (P¼ 0.08). Among patients
with stage I to II disease, miR-21 levels were higher in MV
plasma than in PV plasma (P¼ 0.001), whereas no significant
differences were observed among patients with stage III to IV
disease (Figure 1B). A highly significant association was
observed between MV miR-21 levels and the anatomic location
of the tumor (P¼ 0.003), whereas the association with PV
miR-21 levels was less significant (P¼ 0.01) (Table 1,
Figure 1C).

miR-21 Expression and Metastases
Of the 13 patients who developed metastases during the

course of the disease, 8 had metastases in areas drained by the
MV of the colon: 4 peritoneal metastases, 2 liver metastases,

Medicine � Volume 94, Number 1, January 2015

and 2 anastomotic. Of these 8 patients, 7 had higher miR-21
expression levels in MV plasma than in PV plasma (P¼ 0.02)
(Table 2, Figure 1D).

Copyright # 2015 Wolters Kluwer Health, Inc. All rights reserved.

–1
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P = 0.90P < 0.001

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P = 0.06

miR-21 miR-21

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miR-21 miR-21

A B

D D

FIGURE 1. miR-21 expression levels (fold change) in plasma and tumor. (A) In plasma from healthy C and from the PV and MV of colon
cancer patients and in matched T and N tissue samples from the same patients. (B) In plasma from the PV and MV of colon cancer patients
classified by disease stage. (C) In plasma from the PV and MV of colon cancer patients classified by the anatomic location of the tumor. (D)
In plasma from the PV and MV in 8 patients who developed locoregional metastases. AC¼ ascending colon, C¼ controls, DC¼descend-

era

Medicine � Volume 94, Number 1, January 2015 MIR-21 Expression in Plasma From Mesenteric Versus Peripheral Veins

miR-21 Expression and DFS
Fifty-two patients were evaluable for DFS. Median DFS

was not reached among the 8 patients with low levels of miR-21

in MV plasma, compared with 32.2 months (95% confidence

interval [CI] 27.9–37.5) for the 44 patients with high levels of

miR-21 (P¼ 0.05; Figure 2A). Median DFS was 38.1 months

(95% CI 32.1–44.2) for the 24 patients with low levels of PV

miR-21 and 30.1 months (95% CI 23.5–36.7) for the 28 patients
with high levels (P¼ 0.07; Figure 2B).

To further evaluate whether the levels of miR-21 in both
MV and PV plasma could have a combinatory effect on DFS,
we classified patients in 3 groups: those with high miR-21 levels
in both MV and PV plasma, those with low levels in both MV
and PV plasma, and those with other combinations of miR-21
levels. Median DFS for the 8 patients with low MV and PV
miR-21 was not reached, compared with 29.1 months (95% CI
22.2–35.9) for the 26 patients with high MV and PV miR-21
and 31.2 months (95% CI 24.9–37.5) for the remaining 18
patients (P¼ 0.03; Figure 2C). Based on these findings, we then

descending colon, MV¼mesenteric vein, N¼normal, PV¼periph

compared DFS in the 26 patients with high miR-21 expression
in both MV and PV plasma with all other patients. Median DFS
was 29.1 months (95% CI 22.2–35.9) for these 26 patients

Copyright # 2015 Wolters Kluwer Health, Inc. All rights reserved.

versus 40 months (95% CI 34.8–45.2) for the remaining
patients (P¼ 0.01; Figure 2D).

DISCUSSION
The main cause of death in patients with solid tumors is the

development of metastases. The analysis of plasma and serum
from cancer patients can help identify reliable biomarkers to
predict relapse and metastasis in these patients. Recent findings
suggest that the primary tumor can release proteins and miR-
NAs into the blood, which will organize a microenvironment
known as a premetastatic niche in an area far from the primary
tumor. This premetastatic niche will then provide support for
the nesting and growth of metastatic tumor cells.28,29 Logically,
the veins that are nearest the primary tumor would be most
likely to contain the greatest concentration of these proteins
and miRNAs.

The present study shows that miR-21 expression levels are
significantly higher in MV plasma than in PV plasma. This
finding suggests that the primary tumor in colon cancer releases

l vein, SC¼ sigmoid colon, T¼ tumor; TC¼ transverse colon.

high concentrations of miR-21 in the MV, but that these
concentrations are later diluted in the circulatory system. This
would explain why in other studies, only approximately 30% of

www.md-journal.com | 3

TABLE 1. Patient Characteristics

Characteristics N (%), N¼ 57

P value for Association With miR-21 Expression

Plasma From Mesenteric Vein Plasma From Peripheral Vein

Sex 0.5 0.05
Male 34 (60)
Female 23 (40)

Median age, y 70 0.5 0.2
CEA levels
�5 38 (67) 0.08 0.4
>5 19 (33)

C 19.9 levels
�37 50 (88) 0.1 0.09
>37 7 (12)

Tumor location
Ascending colon 17 (30)
Transverse colon 8 (14) 0.003 0.02
Descending colon 7 (12)
Sigmoid colon 25 (44)

Tumor size, cm
>5 14 (24) 0.05 0.2
�5 42 (74)
unknown 1 (2)

Histological type
Well differentiated 50 (88) 0.5 0.3
Poorly differentiated 7 (12)

Preexistent polyp
Absent 44 (77) 0.5 0.2
Present 13 (23)

Perilymphatic invasion
Absent 52 (91)
Present 4 (7) 0.1 0.1
unknown 1 (2)

TNM stage
I–II 35 (62) 0.8 0.6
III 15 (26)
IV 7 (12)

Adjuvant treatment
Fluoropyrimidines 28 (50) 0.8 0.8
Palliative 5 (8)
None 24 (42)

CEA¼ carcinoma embryonic antigen, TNM¼ tumor, nodule, metastasis.

TABLE 2. Characteristics of 8 Patients Who Developed Locoregional Metastases

Patient
miR-21 Expression in

PV Plasma
miR-21 Expression in

MV Plasma
Disease
Stage

Tumor
location

Type of
Metastasis

1 0.180685 �0.027026 IIIC Sigmoid colon Anastomotic leakage
2 �0.186873 0.036793 IIIB Sigmoid colon Liver
3 �0.073384 0.108137 IIIC Sigmoid colon Peritoneal
4 �0.112819 0.149980 IIA Ascending colon Anastomotic leakage
5 0.117168 0.462750 IIB Transverse colon Peritoneal
6 0.197543 0.511818 IIIC Transverse colon Liver
7 0.180384 0.759566 IIIC Transverse colon Peritoneal
8 0.625005 1.499196 IIB Transverse colon Peritoneal

MV¼mesenteric vein, PV¼ peripheral vein.

Monzo et al Medicine � Volume 94, Number 1, January 2015

4 | www.md-journal.com Copyright # 2015 Wolters Kluwer Health, Inc. All rights reserved.

1.0

0.8

0.6

0.4

0.2

0.0

0 10 20 30 40

P
ro

ba
bi

lit
y

DFS (months)

miR-21 levels in MV

Low
HighP = 0.05

Number at risk

Low
High

8
44

7
35

5
22

4
11

3
3

1.0

0.8

0.6

0.4

0.2

0.0

0 10 20 30 40

P
ro

ba
bi

lit
y

DFS (months)

miR-21 levels in PV

Low
HighP = 0.07

Number at risk

Low
High

24
28

19
23

17
10

8
7

3
3

1.0

0.8

0.6

0.4

0.2

0.0

0 10 20 30 40

P
ro

ba
bi

lit
y

DFS (months)

PV & MV miR-21 levels

P = 0.03

Number at risk

Both low
Other comb
Both high

8 7 5 4
4
7

3

3
18 14 13

9
0

1.0

0.8

0.6

0.4

0.2

0.0

0 10 20 30 40

P
ro

ba
bi

lit
y

DFS (months)

PV & MV miR-21 levels

P = 0.01

Number at risk

Other comb
Both high

Other comb
Both high

Other comb 26 21
21

8 3
3262126

18
79

A B

C D
Both high

Both low

FIGURE 2. DFS according to miR-21 levels (fold change). (A) DFS according to miR-21 expression in plasma from theMV. (B) DFS
according to miR-21 expression in plasma from thePV. (C) DFS in patients with high miR-21 expression in both MV and PV plasma

PV
ll o

Medicine � Volume 94, Number 1, January 2015 MIR-21 Expression in Plasma From Mesenteric Versus Peripheral Veins

miRNAs detected in PV plasma or serum mirrored those found
in the primary tumor.30

Furthermore, miR-21 levels in MV plasma showed a trend
toward correlation with CEA5 levels. In fact, previous studies
have shown that in patients with CRC, CEA5 levels are higher
in the MV than in the PV.31,32 A previous study with a large
cohort of patients20 found a correlation between tumor size and
miR-21 expression in PV plasma; our findings are similar, but
we observed this correlation only in MV plasma. We also found
an association between the anatomic location of the tumor and
miR-21 expression levels in both MV and PV plasma, although
miR-21 expression was higher in MV than in PV plasma. In
addition, recent studies in CRC patients have observed circulat-
ing tumor cells in blood obtained from MVs and from hepatic
veins.33 Taken together with these previous results, our findings
indicate that veins near the tumor are the best source of
biomarkers.

Similar to our findings, previous studies found no associ-
ation between miR-21 expression and tumor stage, which may

compared with those with low expression in both the MV and the
miR-21 expression in both MV and PV plasma compared with a
PV¼peripheral vein.

have been due to the use of different internal controls in these
studies.21 However, among patients with stage I to II disease, we
did observe a significant overexpression of miR-21 in MV

Copyright # 2015 Wolters Kluwer Health, Inc. All rights reserved.

plasma compared with PV plasma, which would confirm
previous reports20,21 that miR-21 is overexpressed in the early
stages of tumor development.

At 4 years of follow-up, patients with high miR-21 levels
in MV plasma had a significantly worse prognosis than those
with low levels; in contrast, no differences were observed
according to miR-21 levels in PV plasma, which suggests that
miR-21 is more easily detected in MV than in PV plasma.
Interestingly, however, patients with high miR-21 expression in
both MV and PV plasma had a significantly shorter DFS than
those with low levels in either MV or PV plasma. We can
speculate that whether initial MV and PV levels are high; PV
levels that remain high throughout follow-up may well be used
to identify patients with a high risk of relapse.

Interestingly, the 8 patients who relapsed and developed
metastases in areas drained by the MV of the colon—the liver
and intestines—had higher levels of MV miR-21 than PV miR-
21. In contrast, metastases in areas not drained by the MV of the
colon—such as the lung—were not associated with miR-21

and those with other combinations. (D) DFS in patients with high
ther patients. DFS¼disease-free survival, MV¼mesenteric vein,

expression levels. In fact, miR-21 has been associated with
hepatocellular tumors in several studies, which have shown that
miR-21 targets several genes—such as MAP2K3,34 PDCD4,35

www.md-journal.com | 5

and PTEN36—leading to the development of hepatocellular
carcinomas. In a large cohort of patients with hepatocellular
carcinomas, array analysis identified a panel of 7 miRNAs
(miR-122, miR-192, miR-21, miR-223, miR-26a, miR-27a, and
miR-801), wherein miR-21 expression levels were able to
distinguish patients from healthy controls.37

It has recently been reported that miRNAs released by the
primary tumor can play a key role in preparing the premetastatic
niche.38,39 miR-21 and miR-29a are released by tumor cells
through exosomes, which bind to the Toll-like receptors of
immune cells. The activation of the Toll-like receptors leads to
the release of tumor necrosis factor-a and interleukin-6, which
in turn prepare the extracellular environment for tumor growth
and dissemination.40 Our findings suggest that the miRNAs
released in the MV may be retained in areas near the primary
tumor (liver and intestines), where they could work to build the
premetastatic niche. To validate these findings, however,
further research on other miRNAs associated with colon cancer
should compare expression levels in MV and PV plasma and
examine the potential association between MV plasma expres-
sion and locoregional metastases. The findings of the present
study will hopefully act as a springboard to strengthen collab-
oration among surgeons, medical oncologists, and molecular
biologists with the aim of improving outcome in colon
cancer patients.

REFERENCES

1. Siegel R, Naishadham D, Jemal A. Cancer statistics, 2013. CA

Cancer J Clin. 2013;63:11–30.

2. Gray R, Barnwell J, McConkey C, et al. Adjuvant chemotherapy

versus observation in patients with colorectal cancer: a randomised

study. Lancet. 2007;370:2020–2029.

3. Yang X, Lee Y, Fan H, et al. Identification of common microRNA-

mRNA regulatory biomodules in human epithelial cancers. Chin Sci

Bull. 2010;55:3576–3589.

4. Schwarzenbach H, Nishida N, Calin GA, et al. Clinical relevance of

circulating cell-free microRNAs in cancer. Nat Rev Clin Oncol.

2014;11:145–156.

5. Allegra A, Alonci A, Campo S, et al. Circulating microRNAs: new

biomarkers in diagnosis, prognosis and treatment of cancer (review).

Int J Oncol. 2012;41:1897–1912.

6. Peinado H, Aleckovic M, Lavotshkin S, et al. Melanoma exosomes

educate bone marrow progenitor cells toward a pro-metastatic

phenotype through MET. Nat Med. 2012;18:883–891.

7. Gibbings DJ, Ciaudo C, Erhardt M, et al. Multivesicular bodies

associate with components of miRNA effector complexes and

modulate miRNA activity. Nat Cell Biol. 2009;11:1143–1149.

8. Roberts CT Jr, Kurre P. Vesicle trafficking and RNA transfer add

complexity and connectivity to cell-cell communication. Cancer Res.

2013;73:3200–3205.

9. Arroyo JD, Chevillet JR, Kroh EM, et al. Argonaute2 complexes

carry a population of circulating microRNAs independent of vesicles

in human plasma. Proc Natl Acad Sci U S A. 2011;108:5003–5008.

10. Lawrie CH, Gal S, Dunlop HM, et al. Detection of elevated levels

of tumour-associated microRNAs in serum of patients with diffuse

large B-cell lymphoma. Br J Haematol. 2008;141:672–675.

11. Zhu S, Si ML, Wu H, et al. MicroRNA-21 targets the tumor

suppressor gene tropomyosin 1 (TPM1). J Biol Chem.

2007;282:14328–14336.

Monzo et al

12. Chang KH, Miller N, Kheirelseid EA, et al. MicroRNA-21 and

PDCD4 expression in colorectal cancer. Eur J Surg Oncol.

2011;37:597–603.

6 | www.md-journal.com

13. Qi L, Bart J, Tan LP, et al. Expression of miR-21 and its targets

(PTEN, PDCD4, TM1) in flat epithelial atypia of the breast in

relation to ductal carcinoma in situ and invasive carcinoma. BMC

Cancer. 2009;9:163. doi:10.1186/1471-2407-9-163.

14. Meng F, Henson R, Wehbe-Janek H, et al. MicroRNA-21 regulates

expression of the PTEN tumor suppressor gene in human hepatocel-

lular cancer. Gastroenterology. 2007;133:647–658.

15. Coppola V, Musumeci M, Patrizii M, et al. BTG2 loss and miR-21

upregulation contribute to prostate cell transformation by inducing

luminal markers expression and epithelial-mesenchymal transition.

Oncogene. 2013;32:1843–1853.

16. Bihrer V, Waidmann O, Friedrich-Rust M, et al. Serum microRNA-

21 as marker for necroinflammation in hepatitis C patients with and

without hepatocellular carcinoma. PLoS One. 2011;6:e26971.

17. Wei J, Gao W, Zhu CJ, et al. Identification of plasma microRNA-21

as a biomarker for early detection and chemosensitivity of non-small

cell lung cancer. Chin J Cancer. 2011;30:407–414.

18. Ma GJ, Gu RM, Zhu M, et al. Plasma post-operative miR-21

expression in the prognosis of gastric cancers. Asian Pac J Cancer

Prev. 2013;14:7551–7554.

19. Komatsu S, Ichikawa D, Takeshita H, et al. Circulating microRNAs

in plasma of patients with oesophageal squamous cell carcinoma. Br

J Cancer. 2011;105:104–111.

20. Toiyama Y, Takahashi M, Hur K, et al. Serum miR-21 as a

diagnostic and prognostic biomarker in colorectal cancer. J Natl

Cancer Inst. 2013;105:849–859.

21. Wang B, Zhang Q. The expression and clinical significance of

circulating microRNA-21 in serum of five solid tumors. J Cancer

Res Clin Oncol. 2012;138:1659–1666.

22. Kanaan Z, Rai SN, Eichenberger MR, et al. Plasma miR-21: a

potential diagnostic marker of colorectal cancer. Ann Surg.

2012;256:544–551.

23. Wang Y, Gao X, Wei F, et al. Diagnostic and prognostic value of

circulating miR-21 for cancer: a systematic review and meta-

analysis. Gene. 2014;533:389–397.

24. Ng EK, Chong WW, Jin H, et al. Differential expression of

microRNAs in plasma of patients with colorectal cancer: a potential

marker for colorectal cancer screening. Gut. 2009;58:1375–1381.

25. Huang Z, Huang D, Ni S, et al. Plasma microRNAs are promising

novel biomarkers for early detection of colorectal cancer. Int J

Cancer. 2010;127:118–126.

26. Wang LG, Gu J. Serum microRNA-29a is a promising novel marker

for early detection of colorectal liver metastasis. Cancer Epidemiol.

2012;36:e61–e67.

27. Pu XX, Huang GL, Guo HQ, et al. Circulating miR-221 directly

amplified from plasma is a potential diagnostic and prognostic

marker of colorectal cancer and is correlated with p53 expression. J

Gastroenterol Hepatol. 2010;25:1674–1680.

28. Sceneay J, Smyth MJ, Moller A. The pre-metastatic niche: finding

common ground. Cancer Metastasis Rev. 2013;32:449–464.

29. Joyce JA, Pollard JW. Microenvironmental regulation of metastasis.

Nat Rev Cancer. 2009;9:239–252.

30. Pigati L, Yaddanapudi SC, Iyengar R, et al. Selective release of

microRNA species from normal and malignant mammary epithelial

cells. PLoS One. 2010;5:e13515.

31. Ivankovics IG, Fernandes LC, Saad SS, et al. Peripheral and

mesenteric serum levels of CEA and cytokeratins, staging and

histopathological variables in colorectal adenocarcinoma. World J

Gastroenterol. 2008;14:6699–6703.

Medicine � Volume 94, Number 1, January 2015

32. Rezende Junior HC, Palma RT, Toloi GC, et al. Carcinoembryonic

antigen levels in the peripheral and mesenteric venous blood of

patients with rectal carcinoma. Arq Gastroenterol. 2013;50:264–269.

Copyright # 2015 Wolters Kluwer Health, Inc. All rights reserved.

M

33. Steinert G, Scholch S, Niemietz T, et al. Immune escape and

survival mechanisms in circulating tumor cells of colorectal cancer.

Cancer Res. 2014;74:1694–1704.

34. Xu G, Zhang Y, Wei J, et al. MicroRNA-21 promotes hepatocellular

carcinoma HepG2 cell proliferation through repression of mitogen-

activated protein kinase-kinase 3. BMC Cancer. 2013;13:469. doi:

10.1186/1471-2407-13-469.

35. Zhu Q, Wang Z, Hu Y, et al. miR-21 promotes migration and

invasion by the miR-21-PDCD4-AP-1 feedback loop in human

hepatocellular carcinoma. Oncol Rep. 2012;27:1660–1668.

Medicine � Volume 94, Number 1, January 2015

Proliferation via HBx-Induced microRNA-21 in Hepatocellular

Carcinoma by Targeting Programmed Cell Death Protein4 (PDCD4)

Copyright # 2015 Wolters Kluwer Health, Inc. All rights reserved.

and Phosphatase and Tensin Homologue (PTEN). PLoS One.

2014;9:e91745.

37. Zhou J, Yu L, Gao X, et al. Plasma microRNA panel to diagnose

hepatitis B virus-related hepatocellular carcinoma. J Clin Oncol.

2011;29:4781–4788.

38. Ghasemi R, Grassadonia A, Tinari N, et al. Tumor-derived micro-

vesicles: the metastasomes. Med Hypotheses. 2013;80:75–82.

39. Squadrito ML, Etzrodt M, De Palma M, et al. MicroRNA-mediated

control of macrophages and its implications for cancer. Trends

Immunol. 2013;34:350–359.

IR-21 Expression in Plasma From Mesenteric Versus Peripheral Veins

40. Fabbri M, Paone A, Calore F, et al. MicroRNAs bind to Toll-like

36. Damania P, Sen B, Dar SB, et al. Hepatitis B Virus Induces Cell

receptors to induce prometastatic inflammatory response. Proc Natl

Acad Sci U S A. 2012;109:E2110–2116.

www.md-journal.com | 7

  • Differential MIR-21 Expression in Plasma From Mesenteric Versus Peripheral™Veins
    • INTRODUCTION
    • METHODS
      • Eligibility and Patient Evaluation
      • Samples
      • RNA Extraction and miRNA Quantification
      • Statistical Analyses
    • RESULTS
      • miR-21 Expression in Plasma and Tissue
      • Patient Characteristics and miR-21 Expression
      • miR-21 Expression and Metastases
      • miR-21 Expression and DFS
    • DISCUSSION
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