Institute of Biomedical Chemistry, Russian Academy of Medical Sciences, ul. Pogodinskaya 10, 119121 Moscow, Russia.
Biochemistry (Mosc). 2012 Apr;77(4):339-41. doi: 10.1134/S0006297912040037.
The level of acute-phase serum amyloid A (SAA) protein in human blood dramatically grows in cancer, often at its early stage, when acute inflammatory signs are not observed. This fact was registered both by immunochemistry and by proteomics methods in different common cancers, such as lung, ovarian, renal, uterine, and nasopharyngeal cancer and in melanoma. It was proposed that SAA is produced by liver in such cases, as in inflammation, high levels of SAA being a part of nonspecific response to tumor. However, that was not always true, because, in many cancers, the protein of interest is produced directly by cancer cells. What is the biological significance of this observation? What preferences do cancer cells obtain due to SAA overexpression? Recent data on melanoma patients have shown that serum amyloid A is able to stimulate immunosuppressive neutrophils to produce interleukin-10 cytokine that suppressed cell immunity. The ability of cancer cells to produce SAA that is acquired during cancer mutagenesis is likely to enhance their resistance to T-cell immunity due to activation of immunosuppressive granulocytes.
人血液中急性期血清淀粉样蛋白 A（SAA）的水平在癌症中显著升高，通常在早期阶段，此时没有观察到急性炎症迹象。这一事实已通过免疫化学和蛋白质组学方法在不同的常见癌症中得到证实，如肺癌、卵巢癌、肾癌、子宫癌和鼻咽癌以及黑色素瘤。有人提出，在这种情况下，SAA 是由肝脏产生的，就像在炎症中一样，高水平的 SAA 是对肿瘤的非特异性反应的一部分。然而，事实并非总是如此，因为在许多癌症中，感兴趣的蛋白质是由癌细胞直接产生的。这种观察的生物学意义是什么？由于 SAA 的过度表达，癌细胞获得了什么优势？最近对黑色素瘤患者的数据表明，血清淀粉样蛋白 A 能够刺激免疫抑制性中性粒细胞产生白细胞介素-10 细胞因子，从而抑制细胞免疫。由于免疫抑制性粒细胞的激活，癌细胞在癌症突变过程中获得产生 SAA 的能力，可能会增强其对 T 细胞免疫的抵抗力。
