Ponzoni M, Guarnaccia F, Corrias M V, Cornaglia-Ferraris P
Oncology Research Laboratory, G. Gaslini Children's Hospital, Genoa, Italy.
Int J Cancer. 1993 Nov 11;55(5):817-23. doi: 10.1002/ijc.2910550521.
Recombinant gamma-interferon (IFN-gamma) has recently been shown to be one of the most effective inducers of neuroblastoma (NB) cell differentiation. Since increasing evidence indicates that expression of MHC class-I and class-II antigens by tumour cells is important for immunorecognition and cell targeting, we tested whether induction of NB cell differentiation by IFN-gamma is followed by expression of HLA class-I and class-II molecules. LAN-5 human NB cell line completely lacks HLA class-I antigens. Their expression was induced in a dose-dependent manner by IFN-gamma. HLA class-II molecules are also absent on LAN-5 cells, but only DP antigens were dose-dependently induced by IFN-gamma, while DR and DQ molecules were unaffected by the treatment. To confirm and extend the immunological data to all the class-II molecules, we performed Northern blot analysis, observing that DP alpha mRNA was induced in a dose- and time-dependent manner. DO beta and DZ alpha genes were also induced peaking after 3 days of IFN-gamma treatment. DR beta and DQ beta genes, which were not induced by IFN-gamma, gave a normal pattern of enzyme restriction by Southern blot. To get an insight into the regulation of HLA class-II gene expression in the neuronal model, we measured the decline of the steady-state HLA class-II mRNA. DO beta mRNA rapidly returned to baseline level after removing IFN-gamma, while the decay rates of DP alpha and DZ alpha mRNA were very slow. This might indicate different regulation at the post-transcriptional level for DO beta mRNA with respect to DP alpha and DZ alpha mRNA. To strengthen these findings we evaluated the half-lives of the mRNA after IFN-gamma induction by means of actinomycin D treatment. HLA-DO beta mRNA had a shorter half-life, while DZ alpha and DP alpha had a longer decay rate. Finally, we report that treatment of LAN-5 cells with cycloheximide did not alter the rate of transcription of the HLA-DP alpha gene, suggesting that no protein factor(s) is/are needed to maintain DP alpha gene expression.
重组γ干扰素（IFN-γ）最近已被证明是神经母细胞瘤（NB）细胞分化最有效的诱导剂之一。由于越来越多的证据表明肿瘤细胞表达MHCⅠ类和Ⅱ类抗原对于免疫识别和细胞靶向很重要，我们测试了IFN-γ诱导NB细胞分化后是否会伴随HLAⅠ类和Ⅱ类分子的表达。LAN-5人NB细胞系完全缺乏HLAⅠ类抗原。IFN-γ以剂量依赖的方式诱导其表达。LAN-5细胞上也不存在HLAⅡ类分子，但只有DP抗原被IFN-γ剂量依赖性诱导，而DR和DQ分子不受该处理的影响。为了将免疫数据确认并扩展到所有Ⅱ类分子，我们进行了Northern印迹分析，观察到DPα mRNA以剂量和时间依赖的方式被诱导。DOβ和DZα基因在IFN-γ处理3天后也被诱导并达到峰值。未被IFN-γ诱导的DRβ和DQβ基因通过Southern印迹呈现正常的酶切模式。为了深入了解神经元模型中HLAⅡ类基因表达的调控，我们测量了稳态HLAⅡ类mRNA的下降情况。去除IFN-γ后，DOβ mRNA迅速恢复到基线水平，而DPα和DZα mRNA的衰减速率非常缓慢。这可能表明DOβ mRNA在转录后水平相对于DPα和DZα mRNA有不同的调控。为了强化这些发现，我们通过放线菌素D处理评估了IFN-γ诱导后mRNA的半衰期。HLA-DOβ mRNA的半衰期较短，而DZα和DPα的衰减速率较长。最后，我们报告用环己酰亚胺处理LAN-５细胞不会改变HLA-DPα基因的转录速率，这表明维持DPα基因表达不需要蛋白质因子。
