Differential expression patterns of N-acetylglucosaminyl transferases and polylactosamines in uterine lesions.
European Journal of Histochemistry 2014; volume 58:2334
Differential expression
patterns of N-acetylglucosaminyl transferases
and polylactosamines in uterine
lesions
A.T.R. Clark,1
V.M.L. Guimarães da Costa,1
L. Bandeira Costa,1
C.L. Bezerra Cavalcanti,1
M.J.B. de Melo Rêgo,1,2
E.I.C. Beltrão1,3
1
Laboratório de Imunopatologia Keizo
Asami, Universidade Federal de
Pernambuco, Recife
2
Núcleo para Inovação Terapêutica,
Universidade Federal de Pernambuco,
Recife
3Departamento de Bioquímica,
Universidade Federal de Pernambuco,
Recife-PE, Brazil
Abstract
Polylactosamine (polyLacNAc) is a fundamental structure in glycoconjugates and it is
expressed in specific cells/tissues associated
with the development and carcinogenesis.
1,3-N-acetylglucosaminyl
transferases
(3GnTs) play an important role in polyLacNAc
synthesis, however the roles of these glycosyltransferases and their products in cancer progression are still unclear. In this sense, this
work aimed to evaluate differential expression
pattern of the N-acetylglucosaminyl transferases and polylactosamines in invasive and premalignant lesions of the uterus cervix. The
expression of 3GnT2 and 3GnT3 were evaluated in normal (n=10) and uterine cervix
lesions (n=120), both malignant [squamous
carcinoma (SC)] and premalignant [cervical
intraepithelial neoplasia (CIN), grades 1, 2
and 3] using immunohistochemistry. Besides,
lectin histochemistry with Phytolacca americana lectin (PWM) and Wheat germ agglutinin
(WGA) was also carried out to observe the
presence of polyLacNAc chains and N-acetylglucosamine (GlcNAc), respectively. The
3GnT3 was expressed in almost all samples
(99%) and 3GnT2 was higher expressed in
disease samples mainly in CIN 3, when compared with normal (P=0.002), CIN 1 (P=0.009)
and CIN 2 (P=0.03). The expression of
polyLacNAc was higher is SC samples, when
compared with normal (P=0.03), CIN 1
(P=0.02) and CIN 3 (P=0.004), and was
observed only nuclear expression in nearly
50% of the SC samples, showing a statistically
[page 152]
significant when compared with normal
(P=0.01), CIN 1 (P=0.002), CIN 2 (P=0.007)
and CIN 3 (P=0.04). Deferring from transferases and polyLacNAc chains, GlcNAc (WGA
ligand) reveals a gradual staining pattern
decrease with the increase of the lesion
degree, being more expressed in CIN 1 lesions
when compared with normal (P<0.0001), CIN
2 (P<0.0001), SC (P<0.0001) and CIN 3
(P=0.0003). Our data reveal that 3GnT2 and
polyLacNAc may be involved in the progression
of the pre-malignant lesions of the human
uterine cervix. In addition, polyLacNAc expression only in the nucleus can be associated a
poor prognostic in uterine lesions.
Correspondence: Eduardo Isidoro Carneiro
Beltrão, Departamento de Bioquímica and
Laboratório de Imunopatologia Keizo Asami,
Universidade Federal de Pernambuco, Recife-PE,
50670-901, Brazil.
Tel. +55.81.21268484 - Fax: +55.81.21268485.
E-mail:
Keywords: cancer, lectin, N-acetylglucosaminyl
transferase, poly-N-acetyllactosamine.
Acknowledgments: this work was financially supported by Conselho Nacional de Desenvolvimento
Científico e Tecnológico (CNPq), Coordenação de
Aperfeiçoamento de Pessoal de Nível Superior
(CAPES) and Fundação de Amparo à Ciência e
Tecnologia do Estado de Pernambuco (FACEPE).
Introduction
Received for publication: 18 October 2013.
Accepted for publication: 26 March 2014.
Squamous carcinomas (SC) of the cervix
usually is one of the most common malignancies in women worldwide1 and arises from
metaplastic squamous mucosa in the region of
the transformation zone;2 it is preceded by a
long phase for pre-invasive disease, called CIN
(cervical
intraepithelial
neoplasia).2,3
Traditionally, CIN are graded as CIN 1, CIN 2
and CIN 3, depending on the degree of differentiation.3 An accurate diagnosis of premalignant lesions is important to clinical management, but the histological diagnosis of CIN can
be complicate.3 Studies of cell surface carbohydrates in these lesions are scarce and they can
be useful for understanding the development
of this type of lesion and its early diagnosis.
Human cells are covered with a dense and
complex array of glycoconjugates (glycoproteins, glycolipids and proteoglycans), that differs between cell types; for example, glycosylation of a single cell type significantly changes
during cell development and differentiation.4-7
Glycosylation is one of the most common
post-translational modifications in eukaryotic
cells.8-10 These glycosylated molecules are
involved in a wide variety of biological events,
such as cell activation,11 differentiation,7,12
infection,13 cell-cell, receptor-ligand, and carbohydrate-carbohydrate
interactions.4,14,15
Furthermore, cell malignant transformations
are often associated with structural alteration
of carbohydrate chains in glycoconjugates,5-7,14
and they may be directly or indirectly involved
in cancer progression and malignancy.5,6,14 The
polyLacNAc structure is a linear glycan containing repeats of the N-acetyllactosamine
(LacNAc) unit (Gal1-4GlcNAc1-3)n. It is a
fundamental. structure of the carbohydrate
chains in glycoproteins and glycolipids,4,16,17
being expressed in specific cells/tissues associated with development and cell-recognition,
binding to several endogenous lectins.16 In
cancer, polyLacNAc and related structures play
This work is licensed under a Creative Commons
Attribution NonCommercial 3.0 License (CC BYNC 3.0).
©Copyright A.T.R. Clark et al., 2014
Licensee PAGEPress, Italy
European Journal of Histochemistry 2014; 58:2334
doi:10.4081/ejh.2014.2334
important roles in cell-cell and cell-matrix
interaction, determining metastatic capacity.4,17,18 Thus, the investigation of their presence may be useful for understanding the
importance of polyLacNAc in cancer lesion.
PolyLacNAc and GlcNAc can be identified in
tissues by Phytolacca americana (PWM), lectin
which binds with high affinity to polyLacNAc
glycans bearing three or more linear N-acetyllactosamine repeats, and from Wheat germ
agglutinin (WGA), respectively. Lectins have
long been used as tools to characterize cell surface glycans because of their substantial selectivity in terms of branching, linkage and terminal modifications of complex glycans.6,19 The
structure of these glycans depends on the glycosylation enzymes, glycosidases and glycosyltransferases, and the presence of appropriate
sugar donors and receptors in the endoplasmic
reticulum and Golgi apparatus of the eukaryotic cell,8,10,16 and they are very complex.5,20 A key
enzyme in this process is 1,3-N-acetylglucosaminyl transferases (3GnTs) that transfers an N-acetylglucosamine (GlcNAc) from
UDP-GlcNAc to a galactose on the nonreducing
end of the carbohydrate chain in a 1,3-linkage.15,21,22 Eight 3GnTs, 3GnT1 to 3GnT8,
have been isolated, and their in vitro activities
have been characterized.4,15-17,22-24 However, the
roles of these multiple 3GnTs on in vivo polylactosamine (polyLacNAc) synthesis are still
unclear.
This study aimed to investi (...truncated)
