Underwater Developments

The expression of the c-erbB-1, c-myc, Ha/N-ras and c-fos oncogenes was investigated in 62 astrocytomas of low, intermediate and high grades by immunogold silver histochemistry. Elevated expression of c-erbB-l was observed in 95%, 48% and 86% of low, intermediate and high grade tumours respectively, c-myc in 5%, 33% and 76% respectively, Ha/N-ras in 0, 43% and 71% respectively and c-fos in 55%, 48% and 52% respectively. Controls included normal brain and tumour sections immunoreacted with pre-immune serum or with antisera absorbed with synthetic peptides. Analysis of co-overexpression revealed that low grade tumours co-overexpressed a maximum of two of these genes, intermediate grade tumours a maximum of three of these genes, while co-overexpression of all four genes was observed in some high grade tumours. Co-overexpression of c-erbB-1 and c-fos was frequently observed in low grade astrocytomas and may be predictive of non-progression. On the other hand, there was a statistically significant increase in the number of tumours overexpressing Ha/N-ras or c-myc with increasing grade of tumour, suggesting that overexpression of these two oncogenes may be indicative of progression. Gliomas are tumours of non-neuronal, supporting cells of the brain. They may be of astrocytic, oligodendroglial or epen-dymal lineage and mixed gliomas may also occur (Zulch, 1986). Astrocytomas are the commonest of the glial tumours and comprise over 45% of childhood (Becker & Yates, 1986) and 50% of adult primary brain tumours (Zulch, 1986). There is considerable variation in the behaviour of astro-cytomas. Some remain as indolent low grade tumours while others are believed to progress to higher grades of malig-nancy. Determination of the likelihood of progression presently relies heavily on histological criteria. Appraisal of the potential for progression would be greatly enhanced by the availability of biological markers, especially if these could be quantitated. Oncogenes have been shown to act as useful markers of progression in some human tumours. Studies of over 800 1990 for review), a tumour of primitive neuronal cells which occurs predominantly outside the brain, have shown that amplification of the N-myc oncogene is associated with rapid progression and poor prognosis. Another oncogene which may serve as a marker of prognosis is c-erbB-2 (or HER-2 or neu). Initial studies correlated c-erbB-2 amplification in breast carcinoma with poorer prognosis (Slamon et al., 1987). However these findings have been disputed due to the considerable variation in other clinical parameters (for review see Maguire & Green, 1989). Recent data, however, indicate that …