Homozygous Deletions of the Multiple Tumor Suppressor Gene

The multiple tumor suppressor gene l (MTS1) located on chromosome 9p has recently been implicated as a candidate tumor suppressor gene in many different tumor types. Cytogenetic analysis and deletion mapping studies have revealed that deletion of chromosome 9p occurs in a signif icant number of primary human astrocytomas. Using multiplex PCR with primers for exon 2 of MISI and for D9S196 from chromosome 9q, we have analyzed 78 primary astrocytic tumors for the deletion of MTSI. After controlling for the contamination of tumor samples with normal cells, homozygous loss of MTSI was found in 13 of 25 anaplastic astrocy tomas (WHO grade III) and in 27 of 46 cases of glioblastomas (WHO grade IV) but in none of seven astrocytomas (WHO grade II). These data suggest that MISI is an important tumor suppressor gene in the malig nant progression of astrocytomas.