Involvement of PKC-iota in glioma proliferation.
Atypical protein kinase C-iota (PKC-iota) protects cells against apoptosis and may play a role in cell proliferation. However, in vivo, the status and function of PKC-iota in human normal brain tissue, gliomas, benign and malignant meningiomas as well as its in vitro status in proliferating and confluent glioma cells, remains unknown.


OBJECTIVE
The objectives of our research were to determine whether expression of PKC-iota is altered either in gliomas or in benign and malignant meningiomas, compared to normal brain. In addition, we wished to establish the expression of PKC-iota in proliferating plus in cell cycle-arrested glioma cell lines, as well as the relationship between PKC-iota siRNA on PKC-iota protein content and cell proliferation.


METHODS
Western blot analyses for PKC-iota were performed on 12 normal brain biopsies, 15 benign meningiomas, three malignant meningiomas and three gliomas.


RESULTS
Results demonstrated no (n = 9) or very weak (n = 3) detection of PKC-iota in normal brain tissue. In comparison, PKC-iota was robustly present in the majority of the benign meningiomas. Similarly, PKC-iota was abundant in all malignant meningiomas and gliomas. Western blotting for PKC-iota in confluent or proliferating glioma cell lines depicted substantial quantities of PKC-iota in proliferating T98G and U-138MG glioma cells. In contrast, confluent cells had either 71% (T98G) or 21% (U-138MG) less PKC-iota than proliferating cells. T98 and U-138 MG glioma cells treated with 100 nm PKC-iota siRNA had lower levels of cell proliferation compared to control siRNA-A and complete down-regulation of PKC-iota protein content.


CONCLUSIONS
These results support the concept that presence of PKC-iota may be required for cell proliferation to take place.
Patel
R
R
Department of Chemistry, University of South Florida, and James A. Haley Veterans Hospital, Tampa, FL 33612, USA.
Win
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H
Desai
S
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Patel
K
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Matthews
J A
JA
Acevedo-Duncan
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M
D001483:Base Sequence; D001932:Brain Neoplasms / Q000201:enzymology / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D005434:Flow Cytometry; D005910:Glioma / Q000201:enzymology / Q000473:pathology*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D034741:RNA, Small Interfering; D000099293:Protein Kinase C-lambda
D007527:Isoenzymes; D011493:Protein Kinase C; D034741:RNA, Small Interfering; D000099293:Protein Kinase C-lambda