Mast Cell Infiltration and Leukotriene Receptor Expression in Colorectal Adenoma: Preventive Application of Malignant Transformation Based on Common Pathological Findings
Masao Sugamata1*, Tomomi Ihara1, Miho Sugamata1, Yasunari Mano2 and Ken Takeda3
1Department of Pathology, Tochigi Institute of Clinical Pathology, Tochigi, Japan
2Department of Clinical Drug Informatics, Tokyo University of Science, Japan
3Department of Hygiene Chemistry, Tokyo University of Science Sanyo Onoda Yamaguchi, Japan
Submission: October 05, 2017; Published: October 25, 2017
*Corresponding author: Masao Sugamata, Department of Pathology, Tochigi Institute of Clinical Pathology, Tochigi, 2308-3, Minamiakatsuka, Nogi, Tochigi, 3290112, Japan, Tel: +81-280-56-1278; Fax: +81-280-56-2792; Email: firstname.lastname@example.org
How to cite this article: Masao S, Tomomi I, Miho S, Yasunari M, Ken T. Mast Cell Infiltration and Leukotriene Receptor Expression in Colorectal
Adenoma: Preventive Application of Malignant Transformation Based on Common Pathological Findings. Canc Therapy & Oncol Int J. 2017; 7(4): 555718.
The prevention of the malignant tumor is thought to be early detection, because the mechanism that tumor cells result, and progresses has not been yet made clear. We have already identified leukotriene receptor expression and mast cells infiltration; these are common pathologic findings in various malignant tumors. In this time, we detected a similar common pathologic finding for polyp of colon suggestive of the precancerous change in the purpose of preventing malignant tumor and examined a malignant transformation risk and the association of these findings. Thirty samples of colorectal adenoma (colonic polyp) tissues obtained from patients with high-grade dysplasia (n=15) or low-grade dysplasia (n=15). These samples were observed mast cells and detected of leukotriene receptors under a light microscope, and were compared using statistical analysis. Mast cells infiltration and the expression of leukotriene receptor were common in the colonic polyp tissues and, similar to malignant tumors, were found.
The tendency with difference had these findings between histopathology classifications. Especially, the number of mast cells was significantly greater within high-grade than within low-grade (P < 0.0001). From these results, the possibility that mast cells and leukotriene receptor were associated with the transitional mechanisms from benign tumor to malignant tumor was shown. The chronic hypersensitivity through leukotriene was thought to have influence on the malignant transformation of colonic polyps. Leukotriene receptor antagonist may have high effect of malignant transformation prevention in colonic polyps.
The main therapies for malignant tumors are surgery, chemotherapy, and radiotherapy. However, we cannot save all patients with these therapies. Therefore, early detection and early treatment are thought to be the most important factors for managing malignant tumors. Furthermore, benign tumors are treated by surgical removal, if necessary, and the patient then receives periodic examinations to detect malignant transformation early. Why is there only this method? It is because the mechanisms of development and of the extension of tumor cells have not yet been made clear.
We have already detected mast cell infiltration and leukotriene (LT) receptors as common pathologic findings in various kinds of tumor tissues, particularly malignant tumor
tissues. Based on these pathologic findings, we proved that a leukotriene receptor antagonist had a treatment effect for malignant tumors using rat spontaneous mammary tumor tissue . Until then, there had been some reports indicating the relationship with LT and tumor that focused on LTB4, which is related to neutrophils and monocytes. LTs that we paid our attention to this time are said to include LTC4, D4, and E4, which is cysteinyl leukotriene (CysLT), and it is closely associated with mast cells and eosinophils. Taking into account the results of this therapeutic investigation, it was thought that a growth factor associated with chronic hypersensitivity was present in malignant tumor tissue, and it was related to histamine, prostaglandin, LTs, and some stromal growth factors. The LT receptor antagonist of interest induced apoptosis in the cells in the rat spontaneous mammary tumor tissue and inhibited
angiogenesis and peripheral nerve formation. Thus, we were
able to conclude that it had a high antitumor effect.
Colonic polyps (colorectal adenomas), which are benign
tumors, are considered precancerous lesions. This study focused
on colorectal adenomas from the perspective of preventing
malignant tumors, and the presence of a common pathologic
finding similar to a malignant tumor and its association with
grade was confirmed. This report is the first to indicate that
the presence of mast cell infiltration and leukotriene receptors
is associated with the transitional mechanisms from a benign
tumor to a malignant tumor.
Thirty samples of colorectal adenoma tissues obtained
from patients who were diagnosed with high-grade dysplasia
(HG: n=15) or low-grade dysplasia (LG: n=15) confirmed by
surgical pathology were evaluated. Tissues were sampled after
the patients gave their informed consent in accordance with the
The tissue samples from colon adenomas were fixed with
10% buffered formalin, and after routine dehydration, they were
embedded in paraffin. Sections 5-μm-thick were stained with
hematoxylin and eosin and examined under a light microscope.
To identify mast cells in each specimen, the paraffin sections
were stained with toluidine blue. Because the granules within
mast cells contain heparin and sulfated glycosaminoglycan,
they were stained metachromatically with toluidine blue.
The 5-μm-thick sections were stained for 30 minutes with a
staining solution containing a 0.05% concentration of toluidine
blue O (Kanto Chemical Co., Inc., Tokyo, Japan) in a citric acid
phosphate buffer (pH 2.5), and they were then examined by
light microscopy. Immunohistochemical staining for cysteinyl
leukotriene receptors (CysLT) 1 and 2 was performed to detect
the expressions of the leukotriene receptors in the tissues
under a light microscope. The 5-μm-thick tissue sections were
stained immunohistochemically using the streptavidin-biotin
method (Histofine SAB-PO Kit; Nichirei, Tokyo, Japan). The
primary antibodies used were polyclonal antibody to CysLT1
and polyclonal antibody to CysLT2 (Acris Antibodies, Inc., San
Diego, CA, USA).
On all sections stained with toluidine blue, mast cells were
observed by light microscopy. In each sample, the number
of mast cells per field (20 objective, 10 ocular) was counted
throughout the specimen, and then the mean number and
standard deviation (SD) were calculated. The mean mast cell
numbers in the HG and LG adenomas were compared using
Welch’s test. Statistical analysis was performed using a software
program, and significance was defined as P<0.05.
Localization of Mast Cells and Detection of Leukotriene
Receptors by Immunohistochemical Staining Mast cell
infiltration and expression of CysLTs were found in all cases
of colorectal adenoma that were examined, and these findings
were common to HG and LG adenomas. These mast cells were
diffusely distributed within the adenomas (Figure 1), and such
a diffuse distribution was very similar to that of mast cells in
lesions of malignant tumor patients that we previously studied
. CysLT-positive cells that were diffusely distributed within
the adenoma were observed in all cases (Figure 2). Positive
reactivity to the anti-CysLT antibodies was detected not only in
tumor cells, but also in fibroblasts, mast cells, and endothelial
cells within the adenoma. In both HG and LG adenomas, there
was a strong tendency for CysLT1 to show a more positive
reaction than CysLT2.
The number of counted fields per specimen was 26.87±10.96
in HG adenomas and 20.50±6.97 in LG adenomas. The mean±SD
mast cell counts were 1.28±2.50 in 7.67±7.08 in HG adenomas
and 1.28±2.50 in LG adenomas; the number of mast cells was
significantly greater within HG adenomas than within LG
adenomas (Figure 3); P < 0.0001).
Given common findings in the tumor tissues, the following
mechanism of oncogenesis and its extension can be proposed
(Figure 4). First, with various stimuli (biologic, chemical, or
mechanical), a hypersensitivity reaction is caused, and then this
hypersensitivity reaction becomes chronic when the stimulation
continues. With this chronic inflammation, the tissue cells
repeatedly undergo damage and repair. Normal cell division
and reproduction are not performed while the cells repeatedly
undergo repair and reproduction (gene mutations may also
be caused then). The cells continue multiplying, and their cell
cycles become abnormal, and, as a result, the cells acquire the
properties of tumor cells.
Current antitumor treatment is basically intended to target
tumor cells. Surgery, radiation, and anticancer drugs remove
tumor cells or cause their necrosis. However, our mechanism
suggests that the tumor will soon recur if we do not block
chronic hypersensitivity inflammation. It is basically impossible
to remove a carcinogen. In other words, the carcinogen varies,
and the presence of chronic hypersensitivity inflammation is
greatly associated with the occurrence of tumors and their
extension, and with respect to the control of factors associated
with this hypersensitivity reaction (inflammatory factors and
growth factors), it is pivotal to the strategy for tumor control.
Several reports have suggested that prostaglandin is one
of the inflammatory factors and is related to tumors [2-6].
However, prostaglandin is present in various organs, and it
has widespread effects. On the other hand, the LT receptor
that we identified has an antagonist, and it is easy to control.
In addition, LT receptors are present in all benign tumors and
malignant tumor tissue and we have already shown the effect of
treatment for the spontaneous rat mammary tumor, as shown
by our conventional study . And the effect of treatment for
animal models of colon cancer is actually reported , too.
Interestingly, we confirmed the leukotriene receptor expression
of tumor tissue by immunostaining, and whereas they confirmed
the receptor of tumor cells by Western blot. In other words, if a tumor tissue can confirm the LT receptor because any method is
enough, the patients with those tumors will obtain a sufficient
antitumor effect from this antagonist.
After our report, an epidemiological analysis using Taiwanese
large healthcare database (medical big data) were reported, this
is the cohort study with which cancer incidence of the users of
LT receptor antagonist and non-users is compared. According to
that report, LT receptor antagonist administration significantly
decreased the risk of various malignant tumors (total cancer
incidence hazard ratio in 0.31, individual: lung cancer; 0.34,
colorectal cancer; 0.35, liver cancer; 0.34, breast cancer; 0.09,
etc.) . Besides, some similar cohort studies are conducted
about the prostaglandin, however, the reduce of cancer incidence
like the LT receptor antagonist is not obtained (for example,
colon cancer; 0.74, rectal cancer; 0.90) . From the comparison
of these reports, the leukotriene receptor antagonist is shown
to be superior to prostaglandin as tumor preventive medicine.
The mechanism involved shows high similarity to that
seen in the remodeling of asthma, and it is also found in
endometriosis, as we have already reported . Furthermore,
the antagonist’s effect in treating endometriosis is very high
[11,12]. This shows that the mechanism of this response is the
basis for the development and extension of various proliferative
lesions. The LT receptor antagonist may become a therapeutic
drug for many proliferative lesions, if LT receptor expression by
the lesion tissue can be confirmed.
With respect to colorectal adenoma, there is thought to be a
difference in the risk of malignant transformation between LG
and HG adenomas. In the present study, a difference was found
in the severity of mast cell infiltration (distribution) between
LG and HG adenomas. Furthermore, a tendency for a difference
in the expression of LT receptors was found in the comparison
between colorectal adenomas and colorectal cancer tissue (in
a previous report). This shows the possibility that mast cells
and LT receptors are involved in the transitional mechanisms
from benign to malignant tumors. Further data accumulation is
necessary to appreciate the details.
Based on the results of this study, chronic hypersensitivity
inflammation through mast cells and LT receptors appears
to have a strong influence on the malignant transformation
of benign adenomas. An LT receptor antagonist may prevent
malignant transformation, as well be useful as treatment for
colorectal adenomas. There is as yet no drug that can prevent malignant tumors. The subjects in whom this LT receptor
antagonist could be used to as a drug to prevent malignant
tumors are the following: patients with a high-risk gene with
malignant tumor, who were diagnosed with a benign tumor
on medical examination, and who were diagnosed as having a
boundary region variant with benign and malignant parts on
histopathology. Only early detection of malignant transformation
through follow-up can be done, and these patients cannot escape
from anxiety. However, aggressive preventive treatment is
enabled if they can take an LT receptor antagonist, and they will
be freed from anxiety.
We discovered mast cells infiltration and LT receptor
expression as the evidence that was common to tissue of colonic
polyps, and the severity of findings correlated with the grade
of adenomas. Therefore, chronic hypersensitivity inflammation
through mast cells and LT receptors appears to have serious
effects the malignant transformation of benign adenomas.