Journal of Cancer Therapy, 2013, 4, 1449-1451
Published Online December 2013 (
Open Access JCT
Inflammation and Carcinogenesis
Yu-Sheng Wu, Shiu-Nan Chen*
Department of Life Science, National Taiwan University, Taipei, Taiwan
Email: *
Received November 6th, 2013; revised November 26th, 2013; accepted December 3rd, 2013
Copyright © 2013 Yu-Sheng Wu, Shiu-Nan Chen. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
In accordance of the Creative Commons Attribution License all Copyrights © 2013 are reserved for SCIRP and the owner of the
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We consider that inflammatory substances play an important role in the carcinogenesis process. In the process, cyto-
kines and growth factor secreted by cells can actively recruit immune cells in the carcinogenesis microenvironment,
further, promote carcinogenesis progression. The carcinogenesis microenvironment even subverted the immune system,
moreover, enhanced the carcinogenesis through immune suppressive mechanisms within the carcinogenesis microen-
Keywords: Inflammation; Carcinogenesis; Microenvironment
1. Introduction
Inflammation is known to be a crucial adaptive response
for animals, and the mechanism is a complex interaction
with molecular mediators even the functions of immune
cells in a microenvironment through a response that oc-
curs at all levels of biological organization [1]. In this
process, cooperation among cells and mediators occurs,
and a wide range of factors are involved in the classical
immune response, including 1) the stage of the inflam-
mation process; 2) the tissue or organ involved; and 3)
whether the inflammation is acute and resolving or
chronic and non-resolving [2]. The inflammation process
involves vascular permeability, active migration of blood
cells, and the passage of plasma constituents into injuri-
ous tissue [3]. Through the infiltration of immune cells,
studies have shown that the inflammation process plays a
crucial role in atherosclerosis [4]. Blood leukocytes, me-
diators of host defenses and inflammation, localize in the
earliest lesions of atherosclerosis in experimental animals.
The study of inflammation in atherosclerosis has afford-
ed considerable new insights into the mechanisms un-
derlying the recruitment of leukocytes [5]. Recently,
studies have indicated the role of inflammation in Alz-
heimer disease (AD) [6]. Inflammatory components re-
lated to AD neuroinflammation include brain cells, such
as microglia and astrocytes, the complement system, and
cytokines and chemokines [7]. Regarding cancer devel-
opment [8], pro-inflammatory cytokines, including inter-
leukin (IL)-1α, IL-1β, IL-6, IL-8, IL-18, chemokines,
matrix metallopeptidase (MMP)-9, and vascular endothe-
lial growth factor (VEGF) are primarily regulated by the
transcription factor nuclear factor (NF)-kB, which is ac-
tive in most tumors and is induced by carcinogens [9].
2. Mediators of Inflammation
Studies have investigated the cytokines involved in the
inflammation response by using various animal models.
The expression of pro-inflammatory cytokines, such as
tumor necrosis factor alpha (TNF)-α, is significantly in-
creased in the adipocytes of obese animals (ob/ob mouse,
db/db mouse, and fa/fa Zucker rat) [10]. The activation
of TNF-α might induce leukocytes express adhesion
molecules on the cell surface [11], leading to diapedesis
through indiv idual vascular endothelial cells [12]. IL-6 is
an adipokine [13] thought to be a mediator of anti-in-
flammation [14] that is produced by adipose tissue and
liver-resident macrophages that are activated in response
to hepatocyte death [15]. IL-6-deficient mice exhibit a
marked decrease in inflammatory response, granulation
tissue formation, and re-epithelialization [16]. The IL-1
family, which includes IL-1α and IL-1β, exhibits strong
pro-inflammatory activ ities an d plays a majo r role in ho st
responses to exogenous and endogenous noxious stimuli
*Corresponding a uthor.
Inflammation and Carcinogenesis
[17]. IL 1 induces the expression of adhesion molecules
on endothelial cells and elicits stromal cells to release
chemokines that promote the recruitment of inflamma-
tory cells at the inflammation site [18]. Such inflamma-
tion occurs significantly in cases of comorbidity and
might contribute to the increased risk of developing car-
diovascular accidents observed in these patients [19].
IL-10, a cytokine with anti-inflammatory properties,
plays a central role in infection that involv es limiting the
immune response to pathogens and thereby preventing
damage to the host [20]. Recently, research has shown
that IL-10 and related cytokines can facilitate the tis-
sue-healing process in injuries caused by infection or
inflammation [21 ]. According to these stud ies, mediators
thought to be involved in the regulation of inflammation
responses such as leukocyte recruitment, adhesion mole-
cule expression, and wound healing in the late phase of
3. Inflammation and Cancer
The inflammatory cells and cytokines present in tumors
are more likely to contribute to tumor growth, progres-
sion, and immunosuppression than they are to induce an
effective host antitumor response [22]. Inflammatory
leukocytes such as neutrophils, monocytes, macrophages,
and eosinophils provide the soluble factors that are
thought to mediate the development of inflammation-
associated cancer, although other cells, including the
cancer cells, also participate [23]. In various forms of
inflammation, the tumor microenvironment contains in-
nate immune cells (including macrophages, neutrophils,
mast cells, myeloid-derived suppressor cells, dendritic
cells, and natural killer cells) and adaptive immune cells
(T and B lymphocytes) in addition to cancer cells and
their surrounding stroma (which consist of fibroblasts,
endothelial cells, pericytes, and mesenchymal cells) [24].
Previously published literature has indicated that the re-
sulting activity of inflammatory mediators, such as cyclo-
oxygenase (COX)-2, creates a tumor-promoting envi-
ronment in which transformed epithelial cells [25] and
COX-2 are inducible by oncogenes ras and scr, IL-1,
hypoxia, ultraviolet lig ht, epidermal growth factor, trans-
forming growth factor beta, and TNF-α [26]. Studies
have expanded on th e concept that inflammation is a cri-
tical component of tumor progression, and many cancers
arise from sites of infection, chronic irritation, and in-
flammation [27]. Investigation of the inflammatory sub-
stances involved in the process may help us prevent even
cure the cancer disease.
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Inflammation and Carcinogenesis
Open Access JCT
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