| Purposes: Brain glioma is the most common type and of highest mortality among the primary intracranial malignancies. China is a country with a high morbidity of glioma, which is among the malignancies with highest yearly morbidity and mortality. Glioma is characterized by invasive growth and extensive infiltration into normal tissues, which brings a worldwide challenge for its treatment, and becomes the important cause for its high death rate of the patients. Even the comprehensive treatment program of surgical resection, combined with radiation therapy and chemotherapy cannot ensure that the median survival of the patients last more than a year. In order to further improve the prognosis of malignant glioma treatment, Medical researchers made constant attempts to develop new molecular biomarkers of diagnostic significance and / or therapeutic value, however, no satisfactory results were achieved.A variety of factors and genes contribute to the process of tumor occurrence, development and deterioration process. Glioma is closely related to a variety of proto-oncogenes, apoptotic genes and tumor suppressor genes which play important parts anywhere in tumor cell proliferation and apoptosis. Both the apoptosis inhibition and imbalance can lead to excessive proliferation of tumor cells, which, in turn, results in tumor growth and affecting the tumor metastasis, and the prognosis. Achievements in biological researches show that the biological effects of such protein molecules as cell adhesion molecules and proteolytic enzymes have been discovered and their functional mechanism in extracranial tumor occurrence, development, invasion and metastasis have been elucidated. However, little has been written on their effects and functional mechanism in brain gliomas. Therefore, it is quite necessary to conduct an in-depth study on the mechanism of glioma development, invasion and metastasis from the view of molecule level.Recent studies have found that neuronal migration factor Slit2 / Robol is closely related to the malignant tumor formation, development, invasion and angiogenesis. Recent experimental studies have found that Slit-Robo signaling system plays an important role in the angiogenesis of malignant tumors. Slit2 expressed by the tumor cells can stimulate the expression of the receptor Robo1 of vascular endothelial cells, inducing angiogenesis and thereby promoting tumor growth. Current research on Slit2 / Robo1 mainly focuses on gastrointestinal tumors including nasopharyngeal cancers, colorectal cancers, and stomach cancers, and on reproductive system cancers such as breast cancers, ovarian cancers, cervical cancer and the like. There has been no report, either at home or abroad, on their role in glioma formation and development, or the possibility of their synergistic effect in glioma angiogenesis and prognosis. Therefore, in-depth study on the expression of Slit2 / Robo1 in brain gliomas, mechanism of action and its relationship with glioma occurrence, development and clinical pathology, can provide new therapeutic ideas for the glioma diagnosis, targeted therapy and prognosis and tend to be the new target for glioma migration and invasive treatment.Methods: The glioma tissue specimens have been obtained from surgical resections with 40 cases randomly selected from November 2013 to January 2014 at Neurosurgery Section, the Second Affiliated Hospital of Hebei Medical University. According to the WHO 2007 classification criteria of central nervous system tumors, 19 cases of Ⅰ ~ Ⅱ grade glioma tissue specimens were classified into low-level group; while the other 21 cases of Ⅲ ~ Ⅳ grade ones were grouped into high-level. and the medical records and data for all the 40 cases were kept very complete and verified by pathological examination in the hospital. The control group is composed of 10 normal tissue samples taken from brain tissues removed from the traumatic brain injury or cerebral hemorrhage patients under the surgical decompression. All selected glioma specimens haven’t undergone any treatment like radiotherapy and chemotherapy before surgery and obtained immediately after surgery, fixed by 10% formalin solution and preserved in liquid nitrogen. The methods of immunohistochemistry(IHC) and real-time quantitative PCR(RT-PCR) are employed in Detection of the expression of Slit2 / Robo1 in gliomas. SPSS16.0 software is used in statistical analysis on the experimental data.Result:1 The result of IHC shows: Slit2 expression is significantly high in normal brain tissue, while it decreases as the tumor grade goes up, till no expression. Slit2 expression rates in the three groups of normal brain tissues, low- level gliomas and high-level gliomas are respectively 100%, 84%, and 28%, which is of distinct statistical significance(P = 0.000); Pairwise comparison between the groups also has distinct statistical significance(P <0.05). Robo1 expression in normal brain tissue is positive and also significant in gliomas, increasing gradually with the increase of malignancy of gliomas. The positive expression rate in the three groups of normal brain tissues, low-level gliomas and high-level gliomas are respectively 80%, 100% and 100%, which is of a statistical significance(P = 0.000). Pairwise comparison between the groups also has statistical significance(P <0.05). With the increase of glioma malignancy, Slit2 expression quantity reduces, while Robo1 expression increases. Slit2- Robo1 expression in normal brain tissues, low-level gliomas and high-level gliomas demonstrate a negative correlation(r =-0.750, P = 0.000). Slit2- Robo1 expression in normal brain tissues and low-level gliomas are negatively correlated(r =-0.233, P = 0.000); Slit2- Robo1 expression in normal brain tissues, and the high-level gliomas are negatively correlated(r =-0.750, P = 0.000); Slit2- Robo1 expression in low-level gliomas and high-level gliomas are in negative correlation(r =-0.977, P = 0.000).2 The result of RT-PCR shows: Slit2 has the highest expression rate in normal brain tissues, while its expression quantity is on the decrease in glioma tumors with the increase of the tumor level, toward no expression. Robo1 has the lowest expression rate in the normal brain tissues, while its expression quantity is on the increase in glioma tumors with the increase of the tumor level. Slit2 and Robo1 expression in the three groups of normal brain tissues, low-and high-level gliomas is of significant statistical significance(P = 0.000). Slit2 pairwise comparison between the groups of normal brain tissues and the low-level gliomas is statistically significant(P <0.05), whereas the comparison between normal brain tissues and high-level gliomas, and the comparison between low-level and high-level gliomas, are of little statistical significance(P> 0.05), which may probably result from the less content of the experimental samples. Robo1 pairwise comparison between the groups is of statistical significance(P <0.05). Slit2- Robo1 expression in normal brain tissues, low-level gliomas, high-level gliomas are not detected to be correlated(r =-0.050, P = 0.94), probably due to the less content of experimental samples. But its expressions in the normal brain tissues and low-level gliomas are negatively correlated(r =-0.552, P = 0.000); the expressions in the normal brain tissues and high-level gliomas are in negative correlation(r =-0.327, P = 0.000); the expressions in low-level gliomas and high-level gliomas are negatively correlated(r =-0.233, P = 0.000). The follow-up study confirms that the patients with Slit2 and Robo1 positive expression have a significantly prolonged survival time than those with Slit2 negative expression and Robo1 positive expression.Conclusion:1 Slit2 expression is significantly high in normal brain tissues, while its expression is on the decrease with the increase of the tumor level, and Slit2 even fails to express in high-level gliomas. The comparison and the pairwise comparison between the three groups of normal brain tissues, low- and high-level gliomas are of statistical significance, which indicates Slit2 is related to the glioma occurrence and the level of malignancy.2 Robo1 expresses positively in normal brain tissues, and over-expresses in gliomas of all levels. The comparison and the pairwise comparison between the three groups of normal brain tissues, low- and high-level gliomas are of statistical significance. As the glioma malignancy level goes up, Robo1 expression gradually increases, which shows that Robo1 may well play an important role in the occurrence and development of gliomas, and that it is related to the malignancy of gliomas.3 Slit2 expression has a significant negative correlation with Robo1 expression, which indicates that the low expression of Slit2 and the high expression of Robo1 in gliomas are probably closely related to invasion, malignant progression and poor prognosis of gliomas. And the loss of Slit2 expression and the increase of Robo1 expression may have a synergistic effect. The difference between the two contributes to the glioma formation, and plays an important role in the pathogenesis and malignant progression of gliomas. Slit2 / Rboo1 may become the new target of glioma migration, invasion treatment.4 IHC survival analysis shows glioma patients with Slit2 and Robo1 positive expressions have a longer survival time than those with Slit2 negative expression and Robo1 positive expression, indicating that Slit2 and Robo1 factors are related to the prognosis of glioma patients. |
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