Epileptogenic Properties of Balloon Cells in Cortical Tubers of Tuberous Sclerosis: Upregulation of Drug Resistance Proteins.

Kang, Nam Gu; Chang, Hong Joen; Ok, Young Cheol; Lee, Rae Seop; Park, Seung Kyu; Lim, Jun Seob; Cho, Kyu Yong; Kim, Hyung Ihl; Kim, Jae Hyoo; Oh, Hyun Sik; Lee, Min Cheol

Original Article

Journal of Korean Neurosurgical Society 2007;41(6): 397-402.

Nam Gu Kang, Hong Joen Chang, Young Cheol Ok, Rae Seop Lee, Seung Kyu Park, Jun Seob Lim, Kyu Yong Cho, Hyung Ihl Kim, Jae Hyoo Kim, Hyun Sik Oh, Min Cheol Lee

¹Department of Neurosurgery, Gwangju Christian Hospital, Gwangju, Korea.
²Department of Neurosurgery, Jeonju Presbyterian Hospital, Jeonju, Korea.
³Department of Neurosurgery, Chonnam National University Medical School, Gwangju, Korea.
⁴Department of Pathology, Chonnam National University Medical School, Gwangju, Korea. mclee@jnu.ac.kr

ABSTRACT

OBJECTIVE
S: Balloon cells and dysplastic neurons are histopathological hallmarks of the cortical tubers of tuberous sclerosis complex (TSC) and focal cortical dysplasia (FCD) of the Taylor type. They are believed to be the epileptogenic substrate and cause therapeutic drug resistant epilepsy in man. P-glycoprotein (P-gp) is the product of multidrug resistance gene (MDR1), and it maintains intracellular drug concentration at a relatively low level. The authors investigated expression of P-gp in balloon cells and dysplastic neurons of cortical tubers in patients with TSC.
METHODS
An immunohistochemical study using the primary antibody for P-gp, as an indicative of drug resistance, was performed in the cortical tuber tissues in two patients of surgical resection for epilepsy and six autopsy cases.
RESULTS
Balloon cells of each lesion showed different intensity and number in P-gp immunopositivity. P-gp immunopositivity in balloon cells were 28.2%, and dysplastic neurons were 22.7%. These immunoreactivities were more prominent in balloon cells distributed in the subpial region than deeper region of the cortical tubers. Capillary endothelial cells within the cortical tubers also showed P-gp immunopositivity.
CONCLUSION
In this study, the drug resistance protein P-glycoprotein in balloon cells and dysplastic neurons might explain medically refractory epilepsy in TSC.

Key Words: Balloon cells; Dysplastic neurons; Multidrug resistance; P-glycoprotein; Tuberous sclerosis complex (TSC)