Human chorionic gonadotropin (HCG) is a placental protein
hormone initially secreted by cells (syncitiotrophoblasts) from
the implanting conceptus. It supports the ovarian corpus luteum,
endometrial lining and consequently maintains pregnancy [1].
The hormone can be detected in blood and urine, as it is the basis
of many pregnancy tests. HCG plays many other roles including
stimulating the onset of fetal gonadal steroidogenesis, promotion
production of corpus luteal progesterone, immuno-suppression
and blockage of phagocytosis of invading trophoblast cells,
cytotrophoblast differentiation, growth and differentiation of fetal
organs [2]. It is well known that a biomarker is any molecular and
chemical changes that can be measured and used to study normal
or abnormal process in the body. A tumor marker, like a biomarker,
is a naturally occurring substance in the body. A tumor marker can
be made by cancer cells or by the body in response to cancer. Tumor
markers can provide information that can be used to screen and
diagnose cancer as well as identify the stage of cancer to monitor a
treatment [3].
It was reported that although mammography, ultrasonography,
computed tomography, magnetic resonance imaging scans, and
tumor marker assays help in the staging and treatment of cancers,
they are usually not definitive diagnostic tests. The diagnosis is
mostly confirmed by biopsy [4]. Human chorionic gonadotropin is
a glycoprotein composed of 237 amino acids, with α subunit (92
amino acids) and β subunit contains 145 amino acids. It can be
used as a tumor marker, as its β subunit is secreted by cell tumor
[5]. Breast cancer is the most often diagnosed tumor of women and
one of the leading causes of death. The effect of human chorionic
gonadotropin on development of cancer is controversial. In fact, for
breast cancer there is evidence that this hormone has a protective
effect against tumor genesis due the differentiation of the mammary
tissue after a full term pregnancy through the down regulation of
estrogen receptors. The mechanisms that explain the pro- and anticarcinogenic
effects are not fully understood yet [6].
HCG increases uterine arterial blood flow and stimulates
angiogenesis in the ovary by stimulating the proliferation of
vascular endothelial cells and the expression of vascular endothelial
growth factor [7]. It was concluded that high expression of β-HCG
is seen more frequently in infiltrative ductal carcinoma with higher
grade. There was a high β -HCG expression in high grade tumors of
more than 5-cm diameter [8]. The beta subunit of human’s chronic
gonadotropin is markedly over expressed by neoplastic cells of
differing histological origin including those present in colon, breast,
prostate and bladder tumors [9].
ISSN: 2574 -1241
