Article
Expression of human endogenous retrovirus K (HERV-K) in human astrocytic tumors
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Published: | April 28, 2011 |
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Objective: Human endogenous retroviruses (HERVs) are suspected to be involved in oncogenesis and tumor progression. HERV-K is strongly expressed in highly progressive tumors as e.g., teratocarcinoma, mamma carcinoma or melanoma. Since human malignant gliomas are known for rapid progression as well, we examined the expression of full length HERV-K mRNA and of splice variants, which are thought to have oncogenic potential, in glioblastoma (GBM) cell lines and biopsies of astrocytic tumors in comparison to normal brain samples.
Methods: Expression of HERV-K mRNAs was determined by semiquantitative RT-PCR in a panel of 6 GBM cell lines, 13 samples of astrocytoma WHO° II, 17 samples of glioblastoma WHO° IV and 3 normal brain biopsies.
Results: Full length mRNA was highly expressed in all tested GBM cell lines. Spliced variants coding for the envelope proteins were clearly detectable in most cell lines, however, in variable amounts. GaMG cells were negative. Rec mRNA was only very weakly detectable. Full length HERV-K mRNA was found in 29 of 30 (96,7%) astrocytic tumor samples and in all of the tested normal brain tissue. Spliced mRNA were rarely or not detectable. The expression level of full length HERV-K and spliced mRNA did not correlate with the WHO grading.
Conclusions: Although expression of different splice variants of HERV-K have been reported to play a role in several malignancies and they were found in variable amounts in GBM cell lines, the lack of their expression in human tumor-biopsies makes a function in astrocytic tumor progression unlikely. However, whether the HERV-K expression in GBM cell lines has any implications for their phenotype is under current investigation.