Investigation into the mechanism of tumorigenesis using p53-deficient epithelial cells

目的：为了剖析p53缺陷型上皮细胞肿瘤转化的基本途径，我们从p53缺陷型小鼠的颌下腺建立了永生化导管/基底细胞系（MSE）。最具挑衅性的影响之一是，MSE成为显着致瘤性（MSA），当共同移植与NIH 3 T3（3 T3）细胞和Matrigel.Methods：10件切碎的颌下腺从p53基因敲除小鼠解剖放置在细胞培养板涂有I型胶原。生长后，进行有限稀释克隆以分选MSE。类似地，还从源自MSE、Matrigel和3 T3的异种移植物的肿瘤亚克隆MSA。进行了各种培养测定和异种移植实验。结果：与MSE相比，MSA细胞形态多样，单层培养可见多核上皮细胞。MSA的增殖率是MSE的2倍。MSA组的平均菌落数高于MSE组，表现出显著的生长行为差异。然而，与高度侵袭性的AdCC相反，这两种细胞系都缺乏侵袭能力。混合接种的MSE和Matrigel重建极化导管，而MSE与Matrigel和3 T3细胞共移植发展成腺瘤和肉瘤的混合瘤。结论：3 T3肉瘤转化是MSE肿瘤发生的关键事件。p53缺失的唾液腺上皮的内在致瘤程序通过3 T3的肉瘤转化由基质-上皮相互作用促进。

Objective: To dissect the fundamental pathway governing neoplastic conversion of p53-deficient epithelial cells, we established an immortalized duct/ basal cell line (MSE) from the submandibular glands of p53-deficient mice. One of the most provocative implications is that MSE became dramatically tumorigenic (MSA), when co-transplanted with both NIH3T3 (3T3) cells and Matrigel.Methods: Ten pieces of minced submandibular glands dissected from p53 null mice were placed on cell culture plates coated with type I collagen. After outgrowth, limiting dilution cloning was performed for sorting MSE. Similarly, MSA were also subcloned from tumors derived from xenografts of MSE, Matrigel and 3T3. A variety of culture assays and xenograft experiments were conducted. Results: As compared with MSE, MSA showed cellular pleomorphism and several multinucleated epithelial cells were visible in the monolayer culture. The proliferation rate of MSA was 2-fold higher than MSE. The average number of colonies was higher in MSA than that in MSE, showing significant difference in growth behaviors. In contrast to a highly invasive AdCC, both cell lines, however, lacked invasive capacity. Inoculation of a mixture of MSE and Matrigel reconstructed polarized ducts whereas co-transplantation of MSE with both Matrigel and 3T3 cells developed mixed tumors of adenoma and sarcoma. Overall, MSA gained some transformed phenotypes in vitro, but apparently lacked malignant properties in vivo.Conclusion : Sarcomatous transformation of 3T3 is a key event in MSE tumorigenesis. The intrinsic tumorigenic programs of p53 null salivary epithelium are promoted by the stromal-epithelial interactions via sarcomatous transformation of 3T3.