الفهرس 
Colorectal CancerOnly 14 pages are availabe for public view
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Abstract
Background: Colorectal cancer (CRC) is a global disease with a high incidence and mortality rates. In Egypt, more than one third of CRC cases occur in individuals aged 40 years or younger and they are diagnosed at advanced stages. Modifiable risk factors include obesity, physical inactivity, diet, and smoking and non-modifiable risk factors such as age, sex play an influential role in CRC etiology. Single nucleotide polymorphisms (SNPs) have been shown as appropriate markers that can predict the susceptibility to various diseases such as CRC.
Objective: This study aimed to investigate the association of SMAD7 gene polymorphism (T > C) with CRC.
Materials and Methods: This study was designed as a case–control association study. After obtaining ethical approval and informed consent, blood samples from 30 CRC patients with colorectal cancer were collected and DNA was extracted. The rs4939827 of SMAD7 was genotyped using TaqMan assay Real-Time PCR.
Results: The C allele of SMAD7 rs4939827 could be protective against colorectal cancer risk. Allele frequency in CRC patients compared to controls (50% vs 55%): OR = 1.58, 95%CI (0.72–3.47), p > 0.05.
Conclusion: The study demonstrated the presence of a non statistically significant relation between T>C polymorphism and CRC However, the (C) allele could be protective for CRC and (T) allele could be associated with a higher stage of CRC.
INTRODUCTION
Colorectal cancer (CRC) is the third most common cancer in males after lung and prostate cancers and the fourth most common in females after breast, cervical and uterine cancer(1). It affects men more than women especially those aged 50 years or older. The incidence and mortality of CRC are variable by region with higher rates in developed countries However, the global burden of CRC is expected to increase by 60%, to over 2.2 million new cases and 1.1 million deaths, by the year 2030(2). In Egypt, more than one third of CRC cases occur in individuals aged 40 years or younger and they are diagnosed at advanced stages. This due to the transition towards more western diet and the lack of screening programs(3).
On a global scale, CRC risk is strongly related to lifestyle factors as it is shown that people with healthy life behaviors as those who are physically active have 27% -52% lower risk of CRC However, CRC risk is multifactorial including genetic and environmental risk factors(4). SO, studying the genetic factors involved in its pathogenesis would help to enhance our knowledge for a better management of the disease(5).
Single nucleotide polymorphisms (SNPs) have been shown as appropriate markers that can predict the susceptibility to various diseases such as cancers. One of the most common polymorphisms associated with CRC risk is located on SMAD7 gene. SMADs are known as receptors and intracellular signal transducers that mediate TGF-β signaling pathway(6). SMAD7 is a kind of inhibitory SMADs and it acts as a negative regulator of the TGF-β signaling pathway. It is differently expressed in human cancers, and it could either sustain or restrain cancer cell growth through its action on TGF-β pathway(7). This pathway has been considered as both a tumor suppressor pathway and a promoter of tumor invasion and progression according to the cancer stage(7).
AIM OF THE WORK
In the present study, we conducted a case–control study to investigate the association between SMAD7 gene polymorphism T>C and the risk of CRC in the Egyptian population.
PATIENTS AND METHODS
An informed oral consent was obtained from each participant before enrolment in the study. Moreover, the study was approved by the Research Ethics Committee of Ain Shams University.
The study was conducted on thirty (30) patients diagnosed with sporadic early CRC recruited from Gastro-Intestinal Tract Surgery Department at Ain Shams University Hospitals during the period from December 2022 till December 2023. In addition, a twenty (20) age & sex- matched were included as control group.
All patients included in this study were subjected to full clinical history taking and clinical examination laying stress on signs of anemia including pallor of skin and mucous membranes and heamic murmurs, presence of palpable mass or signs of intestinal obstruction including constipation, vomiting, and sever intestinal pain. Laboratory investigations including complete blood picture and tumor markers (CEA and CA19-9).
Determination of SMAD7 single nucleotide gene polymorphism (rs4939827) by TaqMan assay using real-time polymerase chain reaction (PCR).
SMAD7 polymorphism detection by melting curve analysis Real Timed PCR:
EDTA blood samples were analyzed for assessment of SMAD7 single nucleotide gene polymorphism (rs4939827) among CRC patients by TaqMan assay using real-time polymerase chain reaction (PCR). Genomic DNA was extracted from EDTA- anticoagulated peripheral whole blood using Thermo Scientific GeneJET Purification Kit. Proteinase K solution and a lysis buffer liberate the DNA in the sample. Impurities are removed with several washing procedures. The DNA is then eluted from the membrane with elution buffer.
The extracted DNA was amplified using TaqMan universal master mix and LightSNiP assay kit for SMAD7 rs4939827. A melting curve was plotted that depends on the addition of a fluorescently labeled hybridization probe during PCR setup. Then the melting curve is generated by slowly heating dsDNA and measuring the dramatic changes in fluorescence that result when the probe denatures or melts away from the amplicon.
Statistical Analysis:
The collected data were revised, coded, tabulated and introduced to Statistical Package for the Social Sciences soft-ware program (SPSS, version 25.0, IBM Corp., USA, 2017-2018). Data were presented and suitable statistical analysis was done according to the type of data obtained for each parameter.
RESULTS
The descriptive and comparative statistics of the demographic and laboratory data between CRC patients (group I) and healthy controls (group II) are illustrated in Table (1). A non- significant statistical difference was found between CRC patients and healthy controls as regard gender, age, smoking, the presence of anemia, leukocytosis and thrombocytopenia (p > 0.05, respectively). Meanwhile, the levels of CEA and CA19-9 were significantly higher in CRC patients compared to the healthy controls (p < 0.05). Descriptive statistics of histopathological and radiological data among CRC patients (group 1) are illustrated in Table (2).