|
|
p53 protein alterations in adult astrocytic tumors and
oligodendrogliomas
Nayak Anupma, Ralte Angela Mercy, Sharma
Mehar Chand, Singh Varinder Paul, Mahapatra Ashok Kumar, Mehta Veer Singh,
Sarkar Chitra
Departments of Pathology, All India Institute of Medical
Sciences, New Delhi, India. Correspondence Address:
Professor, Room No. 1083, 1st Floor, Department of Pathology, All India
Institute of Medical Sciences, Ansari Nagar, New Delhi - 110029, India.
sarkarcs@hotmail.com
Background. p53 is a tumor suppressor gene implicated in
the genesis of a variety of malignancies including brain tumors.
Overexpression
of the p53 protein is often used as a surrogate indicator of alterations in the
p53 gene.
Aims. In this study, data is presented on p53 protein expression in
adult cases (>15 years of age) of astrocytic (n=152) and oligodendroglial
(n=28) tumors of all grades.
Of the astrocytic tumors, 86% were supratentorial
in location while remaining 14% were located infratentorially - 8 in the the
cerebellum and 13 in the brainstem.
All the oligodendrogliomas were
supratentorial.
Materials and Methods. p53 protein expression was
evaluated on formalin-fixed paraffin-embedded sections using streptavidin biotin
immunoperoxidase technique after high temperature antigen retrieval.
Results. Overall 52% of supratentorial astrocytic tumors
showed p53 immunopositivity with no correlation to the histological grade.
Thus,
58.8% of diffuse astrocytomas (WHO Grade II), 53.8% of anaplastic astrocytomas
(WHO Grade III) and 50% of glioblastomas (WHO Grade IV) were p53 protein
positive.
In contrast, all the infratentorial tumors were p53 negative except
for one brainstem glioblastoma.
Similarly, pilocytic astrocytomas were uniformly
p53 negative irrespective of the location.
Among oligodendroglial tumors, the
overall frequency of p53 immunopositivity was lower (only 28%), though a trend
of positive correlation with the tumor grade was noted - 25% in Grade II and
31.5% in grade III (anaplastic oligodendroglioma).
Interestingly, p53 labeling
index (p53 LI) did not correlate with the histopathological grade in both
astrocytic and oligodendroglial tumors.
Conclusions. Thus, this study gives an
insight into the genetic and hence biological heterogeneity of gliomas, not only
between astrocytic tumors vs. oligodendrogliomas but also within astrocytic
tumors with regard to their grade and location.
With p53 gene therapy trials in
progress, this will possibly have future therapeutic implications.
|
