Franz M G, Norman J G, Fabri P J, Gower W R
Department of Surgery, University of South Florida College of Medicine, Tampa, USA.
Ann Surg Oncol. 1996 Nov;3(6):564-9. doi: 10.1007/BF02306090.
The signal transduction pathways important in regulating the growth and differentiation of malignant cells are poorly understood. Recent evidence has implicated activation of the protein kinase C (PKC) family of signaling proteins in pancreatic carcinoma during cytokine-induced cytostasis and differentiation.
A human pancreatic adenocarcinoma (HPAC) cell line was exposed to tumor necrosis factor-alpha (TNF-alpha; 40 ng/ml) for 6 days. Cytostasis and viability were confirmed by daily MTT [(3(4,5)-dimethyl-thiazol-2-yl) 2,5-diphenyl-tetrazolium bromide] and trypan exclusion assay. Protein fractions were isolated daily and subjected to immunoblot analysis for the normal (terminally differentiated) pancreatic ductal cell marker carbonic anhydrase II (CA II) as well as specific PKC isoforms (alpha, beta, gamma, eta, and zeta).
Growth arrest occurred in HPAC cells after exposure to TNF-alpha for 48 h, with viability maintained above 90% throughout the 6-day time course. CA II immunoreactivity was not detected in untreated controls but appeared after 2 days of TNF-alpha exposure, peaking on day 6. Concurrently, TNF-alpha induced the selective downregulation of PKC-alpha, whereas PKC-gamma levels increased. PKC-beta and PKC-eta immunoreactivity did not change. The atypical PKC-zeta isoform developed a doublet banding pattern in response to TNF-alpha, although overall PKC-zeta levels did not change.
TNF-alpha-induced growth arrest and differentiation in HPAC cells is associated with the selective downregulation of PKC-alpha and upregulation of PKC-gamma.
调节恶性细胞生长和分化的重要信号转导途径尚不清楚。最近的证据表明，在细胞因子诱导的细胞停滞和分化过程中，蛋白激酶C（PKC）信号蛋白家族的激活与胰腺癌有关。
将人胰腺腺癌细胞系（HPAC）暴露于肿瘤坏死因子-α（TNF-α；40 ng/ml）6天。通过每日MTT [（3（4,5）-二甲基噻唑-2-基）2,5-二苯基溴化四氮唑]和台盼蓝排斥试验确认细胞停滞和活力。每天分离蛋白质组分，并对正常（终末分化）胰腺导管细胞标志物碳酸酐酶II（CA II）以及特定的PKC亚型（α、β、γ、η和ζ）进行免疫印迹分析。
HPAC细胞在暴露于TNF-α 48小时后出现生长停滞，在整个6天的时间过程中活力维持在90%以上。在未处理的对照中未检测到CA II免疫反应性，但在TNF-α暴露2天后出现，在第6天达到峰值。同时，TNF-α诱导PKC-α的选择性下调，而PKC-γ水平升高。PKC-β和PKC-η免疫反应性没有变化。非典型PKC-ζ亚型在TNF-α作用下出现双峰条带模式，尽管总体PKC-ζ水平没有变化。
TNF-α诱导的HPAC细胞生长停滞和分化与PKC-α的选择性下调和PKC-γ的上调有关。
