Wahlberg P, Fex G, Wennerberg J
Department of Otorhinolaryngology, University Hospital, Lund, Sweden.
Biochim Biophys Acta. 1989 Mar 6;1010(3):287-93. doi: 10.1016/0167-4889(89)90051-7.
The retinol and retinyl ester concentrations in human xenografted squamous cell carcinomas, with various concentrations of cellular retinol-binding protein (CRBP), were studied, as well as the in vivo uptake and esterification in these tumours of labelled retinol, presented as a complex with plasma RBP. The mean retinol concentration in the different tumours was in the range 3.7-6.2 nmol/g protein, and the mean CRBP concentration was between 16 and 69 nmol/g protein. There was a statistically significant correlation between the retinol and the CRBP concentrations in the same tumour (P less than 0.001; r = 0.622). Calculation of the maximal extent of retinol-saturation of CRBP showed low values (range: 9-26%). Retinyl palmitate, the predominant retinyl ester, comprised approx. 70% of the retinyl esters in the tumours. There was no correlation between the concentration of CRBP and that of retinyl palmitate. The uptake of [3H]retinol from intravenously injected retinol-RBP complex was similar in the four human squamous cell carcinomas studied, and not related to their CRBP concentration. 20% of the radioactivity in tumour specimens was lipid soluble, as compared to 96% in liver specimens, showing that in the former a higher fraction metabolised to polar compounds. Taken together, our results suggest that in these squamous carcinoma cells, factors other than cellular CRBP content are the major determinants of net cellular uptake and esterification of retinol. The cellular retinol concentration, on the other hand, appears proportional to CRBP content.
研究了人异种移植鳞状细胞癌中视黄醇和视黄酯浓度与不同浓度细胞视黄醇结合蛋白（CRBP）的关系，以及这些肿瘤中作为与血浆视黄醇结合蛋白（RBP）复合物形式存在的标记视黄醇的体内摄取和酯化情况。不同肿瘤中的平均视黄醇浓度在3.7 - 6.2 nmol/g蛋白质范围内，平均CRBP浓度在16至69 nmol/g蛋白质之间。同一肿瘤中的视黄醇和CRBP浓度之间存在统计学上的显著相关性（P < 0.001；r = 0.622）。计算CRBP视黄醇饱和的最大程度显示值较低（范围：9 - 26%）。棕榈酸视黄酯是主要的视黄酯，约占肿瘤中视黄酯的70%。CRBP浓度与棕榈酸视黄酯浓度之间无相关性。在所研究的四个人类鳞状细胞癌中，静脉注射视黄醇 - RBP复合物后[3H]视黄醇的摄取相似，且与它们的CRBP浓度无关。肿瘤标本中20%的放射性是脂溶性的，而肝脏标本中为96%，这表明在前者中较高比例代谢为极性化合物。综上所述，我们的结果表明，在这些鳞状癌细胞中，除细胞CRBP含量外的其他因素是视黄醇净细胞摄取和酯化的主要决定因素。另一方面，细胞视黄醇浓度似乎与CRBP含量成正比。
