An in vitro histoculture system in which a native-state collagen-sponge gel supports the three-dimensional growth of tumor tissue has been recently developed that allows the culture and drug response assay for most every tumor type. Important features of the histoculture system include the maintenance of three-dimensional tissue architecture and the use of histological autoradiography to measure nuclear incorporation of [3lHJthymidine as an endpoint. We describe in this report in vitro-in vivo correlations for drug response and tumor histology by using human tumor xenografts grown in the native-state three-dimensional histoculture system and as xenografts in nude mice. This comparison eliminates many of the confounding variables seen in most correlative clinical trials. Results demonstrate (i) a very high preservation of in vivo tissue architecture in vitro, (ii) an 86% accuracy in vitro of predicting drug resistance in vivo using suprapharmacologic doses of drugs in vitro, and (iii) an overall predictive frequency of drug resistance and sensitivity ranging from 53% for 5-fluorouracil to 78% for doxorubicin.An important need in cancer treatment is an in vitro means by which to accurately assess chemosensitivity of all types of human tumors and relevant normal tissue for comparison. There have been many attempts at in vitro drug response testing (1-3). As has been pointed out (3), in vitro assays thus far performed often do not predict in vivo drug response accurately. Many studies have shown that monolayer cultures of cells are often much more sensitive to drugs than the same cells in a three-dimensional configuration (4). We have, therefore, developed a primary culture system in which a native-state collagen-sponge-gel support allows most types of human cancer to grow in vitro at <90% frequency with maintenance of tissue architecture, tumor-stromal interaction, and differentiated functions (5-9). The native-state culture system allows multiple endpoint analysis including proliferation indices of cells determined by histological autoradiography after [3H]thymidine incorporation (5-10).The native-state histoculture system theoretically should have a high potential to be utilized for a predictive assay of tumor chemosensitivity since tumor and normal tissue remain in vitro highly similar to the in vivo state. In this report we describe experiments to determine the degree to which the native-state system, using [3H]thymidine incorporation as an endpoint, can predict in vivo drug response.We have correlated drug response of human tumor xenografts in histoculture and the same tumors implanted in nude mice, both systems providing highly controlled experimental conditions (11). Tumor histology is also correlated in histoculture and in nude mice.
MATERIALS AND METHODSIn Vitro Drug Sensitivity. Histoculture. Tissues were explanted as has been described (5-10). Briefly, after tissues were surgically removed, they were divided into 1-to 2-mm diameter pieces. Six pieces of tissue were excised from different areas of...
An important need in cancer research and treatment is a physiological means in vitro by which to assess the proliferation capacity of human tumors and corresponding normal tissue for comparison. We have recently developed a native-state, three-dimensional, gel-supported primary culture system that allows every type of human cancer to grow in vitro at more than 90% frequency, with maintenance of tissue architecture, tumor-stromal interaction, and differentiated functions. Here we demonstrate that the native-state culture system allows proliferation indices to be determined for all solid cancer types explanted directly from surgery into long-term culture. Normal tissues also proliferate readily in this system.
We have adopted an in vitro three-dimensional histoculture technique for assay of androgen sensitivity in explants of human benign prostatic tissue. The assay is based on the uptake of 3H-thymidine/micrograms protein in explants of prostate incubated in parallel with dihydrotestosterone (DHT) and hydroxyflutamide (HF) controls. The ratio of 3H-thymidine/micrograms protein in DHT treated samples per 3H-thymidine/micrograms protein in HF treated samples provides an index of androgen sensitivity. The DHT/HF index measured in 24 BPH specimens averaged 3.6. To determine the specificity of the HF effect, we measured the DHT/HF index in a single prostate at different concentrations of HF in the presence of fixed concentrations of DHT (2 x 10(-8) M) and noted a dose-response relationship. In addition we noted no effects of HF on 3H-thymidine incorporation over a range of 2 x 10(-4)M compared to 2 x 10(-7)M, except at the highest concentration. Of surprise was the finding of an average DHT/HF index in 5 different nonprostate tissues, including breast, uterus, colon, kidney, and thyroid, that was similar to the index found in prostates. We plan to adapt this androgen sensitivity assay to measure the DHT/HF index in biopsy-size samples of prostate, since such an assay could then be utilized to determine androgen sensitivity in individual patients with prostate cancer.
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