Research Publications - College of Medicine and Health Science

Department of Pharmacology
76
Pharmacogenetics: Oxidation by enzymes encoded
at the CYP2D6 locus is the main route of
elimination for a large number of drugs including
many commonly prescribed in psychiatric
practice such as antidepressants and neuroleptics.
The CYP2D6 locus is highly polymorphic
and numerous mutant CYP2D6 alleles are
currently known including defective alleles
which yield no functional protein product and
duplicated active alleles which cause ultrarapid
oxidation. Two CYP2D6 oxidation phenotypes
EM (extensive metabolisers) and PM (poor
metabolisers) are commonly recognized. These
phenotypes can be accurately predicted by genotyping.
The clinical implications of the CYP2D6
polymorphism are of potential importance to
psychiatric practice in the UAE since tricyclic
antidepressants are widely prescribed for treatment
of depression. These drugs have a small
therapeutic index and unpleasant side-effects
or therapeutic failure is commonly encountered
when fixed dose regimens are used. There are
only very few and conflicting data concerning
the distribution of CYP2D6 phenotypes in Arab
populations and no genotyping studies have
ever been carried out. We aim to determine the
frequency of the most common CYP2D6 alleles
in the local population using allele specific PCR
methodology and to assess the relevance of the
CYP2D6 polymorphism to psychiatric practice in
the UAE (published in PlosOne).
Dr. Samir Attoub
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My research is focused on the role of PI3K/Akt/
NFκβ pathway as a driving force behind lung
and colon cancer progression (apoptosis, invasion,
angiogenesis and metastasis) using siRNA
technology and in parallel screening of potential
anti-cancer drugs.
1. Identification of Akt isoforms involved in
colon cancer survival and invasion
The PI3K/Akt/NFκB signaling cascade is constitutively
activated in cancers. Akt is linked to
the transforming activity of c-src, c-kit, c-met
oncogenes and growth factors, such as EGF and
IGF receptors. Drugs targeting receptor tyrosine
kinases (ErbB2/HER2 and ABL/c-kit) impact the
PI3K/Akt pathway. Consequently, the inhibition
of Akt is considered to be an attractive cancer
therapeutic target. Three isoforms of Akt (Akt1/
PKBα, Akt2/PKBβ, and Akt3/PKBγ) are over-ex-
pressed and activated in cancers, but the degree
of functional redundancy between them on
cancer cell survival and invasion are unclear. The
identification of the Akt isoform that is the most
promising target for cancer therapy is unknown
and will be addressed in the following specific
objectives:
a. To explore the respective roles of Akt-1, -2
and -3 in cancer cell survival, invasion, tumor
growth and metastasis, studies will be conducted
using RNA interference technology in LNM35
human lung cancer cells and HT29 human colon
cancer cells.
b. To characterize the ability of different isoforms
of Akt (Akt-1, -2 and -3) to transactivate
different subsets of target genes to orchestrate
either cell survival or invasion. This will be
investigated in colon and lung cancer cells using
microarray analysis.
The effects of knockdown of Akt-1, -2 or -3 on
cellular survival will be determined by cellular
viability, DNA fragmentation, cell cycle and
TUNEL assays, caspases activity, PARP cleavage,
cytochrome-c release and expression of
pro- and anti- apoptotic proteins. The impact
of Akt-1, -2 or -3 silencing on invasion will be
investigated using the collagen type I and the
chick heart invasion assays, cell-cell and cell-matrix
adhesion and expression of E-Cadherin. The
effect of knock down of the Akt’s on HT29 cell
line on tumour growth will be tested in nude
mice. In addition, we will asses the development
of new blood vessels (CD31 antibody), the
presence of apoptotic cells (caspase 3 activity),
and proliferative activity (ki67 antibody). We’ll
test the therapeutic impact of the Akt isoforms
inhibition on metastasis using the highly
invasive and metastatic lung cancer cell line
LNM35 targeting the lymph nodes and lungs.
This cell line is stably transfected with a vector
encoding luciferase, to allow a rapid and reliable
quantification of micro-metastases. To identify
the mechanisms underlying the effects of Akt
isoform inhibition, we will search for differentially
expressed genes using microarray analysis
and confirm the results by real-time RT-PCR.
It is anticipated that this project will provide
evidence that targeting Akt-1 and/or -2 is a
promising strategy for the treatment of colon
and lung cancer.