CD 117 tyrosine kinase receptor expression in gliomas

Gliomas are the most common primary brain tumors. Despite therapeutic advances, the majority of gliomas do not respond to either chemo or radiotherapy. CD117, the gene product of c-kit has been expressed in glial tumors. Because gastrointestinal stromal tumors [GISTs] that express CD117 respond dramatically to treatment with tyrosine kinase inhibitors, identification of glial tumors that express CD117 might open new therapeutic approaches for treatment of these tumors. This work was planned to study the role of CD117 [KIT] in the development and progression of gliomas mainly astrocytomas. Also, to assess if CD117 might serve as a biomarker for those gliomas that might respond to tyrosine kinase inhibitors. We studied 71 cases of gliomas. They were 59 astrocytomas, 9 ependymomas, 2 mixed oligoastrocytomas and single case of anaplastic oligodendroglioma. Paraffin embedded sections were immunostained using primary antibodies against CD117. Antigen antibody reaction was detected by streptavidin-biotin kit. In the present work, CD 117 immunoreactivity was noted in different grades of astrocytomas. The CD 117 average weighted scores showed gradual upregulation with increasing grade from pilocytic astrocytoma [16.7%]-diffuse astrocytoma grade II [33.3%]-anaplaslic astrocytoma [66.7%]-glioblastoma multiforme [79.3%.]. Majority of the gliomas [57.7%.] were found to express CD117 to varying degrees, and high grade tumors [78.6%] had a higher proportion of CD117 expression than low grade tumors [27.6%]. In 21.12% of studied cases, the CD117 was expressed in endothelial cells of tumor blood vessels. Twelve cases of them [80%] were most prominent in microvascular proliferations of high grade tumors and eleven cases of them showed strong intensity. High grade astrocytomas [especially glioblastoma multiforme] showed more frequent and strong expression of CD117, this indicate that CD]117 may has possible role in early astrocytoma tumorigenesis and in progression. Also, CD117 may serve as a biomarker for those gliomas that respond to tyrosine kinase inhibitor drugs