الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 220 |  |  |
| | | from | 220 | | |
Abstract
Colorectal cancer is the third most common cancer in men and the second in women (Ferlay et al., 2015). There are significant international variations in the distribution of colorectal cancer (center et al. 2009 ; Parkin et al.,2011) with 60% of CRC occurring in developed regions and countries that have experienced a rise in prosperity, such as Japan. The highest rates of CRC are in Western Europe and Australia/New Zealand, and the lowest rates are in Africa (excluding Southern Africa) and South-Central Asia (Ferlay et al., 2015).
In Egypt, The Cancer Pathology Registry of National Cancer Institute, Cairo University showed that during the years 2003-2004, colorectal cancer occupied the first rank among digestive system malignancies (15.78%) and the fifth among all cancers (4.34%) (Mokhtar et al., 2007). And according to the Pathology Based Cancer Registry 2001-2010, Faculty Of Medicine, Ain Shams University, colorectal cancer represents the first rank of digestive system malignancies ( 42.6%) and ( 8.8) % of total malignancies (Helal et al.,2015)
Many Factors such as tumor size, histological type, presence of signet ring morphology as well as lymph node involvement are well known factors that influence the outcome in CRC (Ola Marzouk and John Schofield, 2011).
Moreover, poor differentiation, old age, lymphovascular invasion, and perineural invasion are associated with high risk for recurrence or metastasis in patients with T2N0M0 colorectal caner (Xu et al., 2016).
Msi-1 is a neural RNA-binding protein which was initially identified as a neuronal stem cell marker and, more recently, identified as an intestinal stem cell marker (Dawei et al., 2011).
Msi-1 was shown to be expressed in the small intestine at the 4th–6th cell position from the bottom of the crypts and in the deepest portion of the crypts in the large intestine, where the concentration of putative stem cells is considered to be high (Humphries et al., 2008).
The expression of Msi-1 was detected in human colorectal adenoma cells and colon cancer tumors. Interestingly, knockdown of Msi-1 in the colon adenocarcinoma xenografts resulted in the arrest of tumor growth. These results suggest that Msi-1 might play an important role in tumorgenesis and tumor progression (Sureban et al., 2008 ).
Worldwide, few studies were performed to assess Msi-1 expression and its prognostic significance in CRC and no such studies were conducted in Egypt in particular.
The aim of this study was to evaluate the immunohistochemical expression of Msi-1 in CRC and to correlate it with different clinicopathological parameters aiming at identifying the potential prognostic significance of Msi-1 in CRC.
This study included 50 cases of CRC, which were collected from the Pathology Department and Department of Clinical Oncology and Nuclear Medicine –Faculty of Medicine- Ain Shams University,during the period from 2010-2015. The selected blocks were sectioned 5µm thick sections and immunostained using Concentrated Rabbit polyclonal antibody against Msi-1 from Genetex company, USA. Semi quantitative assessment of immunostaining results followed by statistical analysis to correlate it with different clincopathological prognostic parameters was carried out.
We found that Msi-1 is commonly overexpressed in CRC, as we observed Msi-1 immunoreactivity in 88% of studied cases.
A statistically significant correlation was observed between Msi-1 expression and depth of invasion of the tumor (T stage), and between Msi-1 expression and existence of metastasis at time of diagnosis or during follow-up. A statistically significant correlation was also observed between Msi-1 expression and response of metastasis to chemotherapy whether it stays stationary, regresses or progresses.
No statistically significant correlation was observed between Msi-1 expression and patient`s age, patient`s sex, tumor size, tumor site, histologic grade, histologic type, recurrence, stage group, modified Duke`s stage, peri-neural and lympho -vascular invasion.
The clinical implications of our findings include possible use of Msi-1 expression as a prognostic marker for CRC cases. Aberrant overexpression of Msi-1 during metastasis of colon cancer also suggests that it is a potential therapeutic target but this point needs further studying.