Ada A. O. (Executive)
Project Supported by Higher Education Institutions, 2010 - 2013
The bioactivation of many carcinogenic compounds occur after oxidation
with phase I enzymes which they undergo extensive metabolic activation by cytochrome
P450 (CYP) enzyme superfamily. Thus changes in the expression of CYPs is an effective
toxicological factor. One of the most important groups of metabolic enzymes
which are responsible for the disposal of toxic substances is CYP superfamily.
An important isozyme of this superfamily is CYP1B1 isozyme. CYP1B1 is a key
enzyme involved in the formation of estrogen metabolites and activation of
environmental carcinogens such as polycyclic aromatic hydrocarbons. The
products formed after metabolic activation become substantially more toxic than
the original compound. There are five different single nucleotide polymorphisms
exist in the human CYP1B1 gene which cause changes in enzyme activity, namely Arg48Gly (CYP1B1*2), Ala119Ser (CYP1B1*2), Leu432Val (CYP1B1*3),
Asn453Ser (CYP1B1*4) and Ala443Gly (CYP1B1*7).
Generally mutant CYP1B1 isozymes show higher activity when compared with
the wild type. In
individuals with high CYP1B1 activity, due to the formation of mutagenic and
carcinogenic active intermediates of both endogenous substances and exogenous
environmental chemicals, the risk of developing different types of cancer may
also be higher. Polymorphic gene frequencies in several populations are
reported to be different. In addition, there are differences within ethnic
groups. In Turkey there exist very few studies on CYP1B1 polymorphisms and the
incidence of these polymorphisms in Turkish population has not been clarified.
Therefore, in this study the Arg48Gly (CYP1B1*2), Ala119Ser
(CYP1B1*2), Leu432Val (CYP1B1*3), Asn453Ser (CYP1B1*4) and Ala443Gly (CYP1B1*7) polymorphisms were determined in
125 men and 125 women, a total of 250 volunteers. Results of this study provide
information about the polymorphic distribution of CYP1B1 gene in Turkish population
and give the possibility for comparison with other populations. Also the
results can constitute basic data for determining the extent of the effect of
these polymorphisms in various diseases and cancer.