Balch G, Izzo F, Chiao P, Klostergaard J, Curley S A
Department of Surgical Oncology, University of Texas M. D. Anderson Cancer Center, Houston 77030, USA.
Ann Surg Oncol. 1997 Mar;4(2):149-55. doi: 10.1007/BF02303798.
In a small pilot study, thymostimulin (TP-1) produced tumor regression in almost 50% of patients with hepatocellular cancer (HCC) who were treated with TP-1 alone. However, the mechanism of the TP-1-mediated antitumor effect against HCC is unknown.
Human hepatocytes and Kupffer cells were isolated from liver biopsy specimens by collagenase infusion and counterflow elutriation. Hepatocytes and Kupffer cells were incubated in vitro with clinically relevant doses of TP-1. Cell-free supernatant levels for a panel of growth factors and monokines were determined by enzyme-linked immunosorbent assay. The cytotoxic activity of TP-1 alone of TP-1-stimulated hepatocyte and Kupffer cell supernatants against Hep G2 and Hep 3B human HCC cells in vitro was measured by MIT assay.
Doses of TP-1 up to 100 micrograms/ml produced no cytotoxicity against Hep G2 or Hep 3B cells. Furthermore, supernatants from TP-1-treated hepatocytes produced no cytotoxicity against Hep G2 or Hep 3B cells, and TP-1 did not stimulate the release of transforming growth factor (TGF)-alpha, TGF-beta, or hepatocyte growth factor. TP-1-treated Kupffer cell supernatants produced significant cytotoxicity against Hep G2 cells but produced no cytotoxicity against Hep 3B cells. Kupffer cells stimulated by TP-1 released significant amounts of tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1 alpha, and IL-6 compared with control Kupffer cells (p < 0.01). The activity of TP-1-treated Kupffer cell supernatants against Hep G2 cells was blocked by anti-TNF-alpha antibodies, whereas neither anti-IL-1 alpha nor anti-IL-6 antibodies blocked cytotoxicity.
These results demonstrate that TP-1 cytotoxicity against human HCC cells is not mediated directly or through hepatocytes, but occurs through activation of Kupffer cells and release of TNF-alpha. Understanding the mechanism of TP-1 cytotoxicity against human HCC has been used to plan a phase 1 trial of TP-1 combined with regional infusion of doxorubicin to treat unresectable HCC.
在一项小型试点研究中，胸腺刺激素（TP - 1）在几乎50%单独接受TP - 1治疗的肝细胞癌（HCC）患者中产生了肿瘤消退。然而，TP - 1介导的针对HCC的抗肿瘤作用机制尚不清楚。
通过胶原酶灌注和逆流淘析从肝活检标本中分离出人肝细胞和库普弗细胞。将肝细胞和库普弗细胞与临床相关剂量的TP - 1在体外孵育。通过酶联免疫吸附测定法测定一组生长因子和单核因子的无细胞上清液水平。通过MTT法测量单独的TP - 1以及TP - 1刺激的肝细胞和库普弗细胞上清液对Hep G2和Hep 3B人肝癌细胞的体外细胞毒性活性。
高达100微克/毫升的TP - 1剂量对Hep G2或Hep 3B细胞无细胞毒性。此外，TP - 1处理的肝细胞的上清液对Hep G2或Hep 3B细胞无细胞毒性，并且TP - 1不刺激转化生长因子（TGF）-α、TGF -β或肝细胞生长因子的释放。TP - 1处理的库普弗细胞上清液对Hep G2细胞产生显著的细胞毒性，但对Hep 3B细胞无细胞毒性。与对照库普弗细胞相比，TP - 1刺激的库普弗细胞释放大量肿瘤坏死因子-α（TNF -α）、白细胞介素（IL）-1α和IL - 6（p < 0.01）。抗TNF -α抗体可阻断TP - 1处理的库普弗细胞上清液对Hep G2细胞的活性，而抗IL - 1α和抗IL - 6抗体均不能阻断细胞毒性。
这些结果表明，TP - 1对人肝癌细胞的细胞毒性不是直接介导的，也不是通过肝细胞介导的，而是通过激活库普弗细胞和释放TNF -α发生的。了解TP - 1对人肝癌细胞的细胞毒性机制已被用于规划TP - 1联合阿霉素区域灌注治疗不可切除HCC的1期试验。
