Two new human neuroblastoma cell lines exhibiting tumorigenesis and metastasis in the nude mouse model.

BACKGROUND: Human neuroblastoma cell lines are notoriously difficult to establish in culture and use in murine hosts. MATERIALS AND METHODS: Two new human neuroblastoma cell lines, NK and ND, were established and studied for growth patterns in nude mice, growth in soft agar, cell cycle analysis, apoptosis (Hoechst- merocyanine 540 test), metalloproteinase expression (zymograms), and morphological differentiation by dibutyryl cyclic AMP (dCAMP). RESULTS: Both cell lines formed tumors in 6/9 nude mice within 5-31 days after subcutaneous inoculation, and metastases after intravenous tail vein injection. Both grew in soft agar. DCAMP induced morphologic differentiation in both, and inhibited cell culture growth without apoptosis. Zymograms of supernatants from cultures revealed 72-kDa metalloproteinase and higher molecular bands that did not change with dCAMP treatment. Cultures derived from murine metastatic foci exhibited 72, 82 and 85-kDa proteins, with strong 92-kDa bands after dCAMP treatment. CONCLUSION: New human neuroblastoma cell lines were established that are easily used in nude mice, and express metalloproteinases.

Reduction of translation initiation factor 4E decreases the malignancy of ras-transformed cloned rat embryo fibroblasts.

Expression of the T24ras oncogene induces malignancy (tumor growth, invasion and metastasis) in cloned rat embryo fibroblasts (CREF T24). In CREF T24, the rate of phosphorylation of eukaryotic translation initiation factor 4E (eIF-4E) is increased, resulting in increased protein synthesis rates. We have recently shown that reducing the protein levels of eIF-4E in CREF T24 (AS4E line) markedly decreases soft-agar colonization, increases tumor latency periods and increases tumor doubling times without significantly altering monolayer growth. In this study, cells with reduced eIF-4E had delayed and reduced invasiveness and decreased experimental metastasis. Furthermore, reduced eIF-4E levels correlated with decreased expression of the metastasis-associated 92-kDa collagenase type-IV and exon-6 variants of the CD44 adhesion molecule [CD44(6v)]. Reduced eIF-4E levels correlated inversely with increased levels of the putative metastasis-suppressor protein nm23. Cell lines established from AS4E tumors and lung metastases exhibited increased levels of eIF-4E protein and protein synthesis rates compared to the AS4E line. Tumor-derived AS4E had the shortened tumor latency periods of CREF T24 but displayed the slow tumor-growth rates of AS4E. Tumor-derived AS4E exhibited the metastatic capacity of CREF T24 controls. Furthermore, tumor- and lung-nodule-derived AS4E expressed levels of CD44 (6v) and the 92-kDa collagenase type IV comparable to CREF T24 and displayed reduced levels of nm23 relative to AS4E. These results demonstrate that eIF-4E is an important effector molecule involved in oncogenic p21ras-induced malignant transformation.