Three cancer cell lines, IMC-2, IMC-3 and IMC-4, were established from a single tumor of a patient with maxillary cancer. We examined responses to epidermal growth factor (EGF) of these 3 cell lines with regard to cell growth and tumor invasion. The growth rate of IMC-2 in nude mice was markedly faster than that of the IMC-3 and IMC-4 cell lines. Assay for invasion through fibrin gels showed significantly enhanced invasive capacity of IMC-2 cells in response to EGF, but no change for IMC-3 and IMC-4 cells. We examined response to EGF of IMC-2 cells with regard to expression of a growth-related oncogene (c-fos), proteinases and their inhibitors. Expression of c-fos was transiently increased in IMC-2 cells at rates comparable to those seen in the 2 other lines in the presence of EGF. There was no apparent effect of EGF on the expression of urokinase-type plasminogen activator and 72-kDa type-IV collagenase in IMC-2 cells. In contrast, EGF specifically enhanced the expression of plasminogen activator inhibitor-I (PAI-I) and tissue inhibitor of metalloproteinases-I (TIMP-I) in IMC-2 cells. Our data suggest that proteinase inhibitors or other related factors may play an important role in tumor growth and invasion in response to EGF.

The authors established five cell lines from a human head and neck tumor. The five cell lines (HC-2, HC-3, HC-4, HC-7, and HC-9) exhibited different sensitivities to Adriamycin, cisplatin, bleomycin, 5-fluorouracil, vincristine, and daunomycin. The D50 was 200 ng/ml Adriamycin (doxorubicin) for HC-7 and 45 ng/ml for HC-2. At the inception of long-term culture (11 months) in the absence of any drug, the sensitivity to Adriamycin of HC-7-5 (subcloned from HC-7) was 3.4 times greater than that of HC-2-6 (subcloned from HC-2); by 11 months, it decreased to 1.6 times that of HC-2-6. The cytocidal action of Adriamycin on HC-2-6 and HC-7-5 was potentiated when Adriamycin was combined with verapamil or cepharanthine. Cepharanthine also potentiated daunomycin and vincristine (VCR) against HC-2-6 and HC-7-5 cells, and it almost completely overcame drug-resistance to daunomycin and vincristine in HC-7-5/VCR, a multidrug-resistant variant isolated after long exposure to vincristine of HC-7-5 cells in culture. The cellular accumulation of [3H]-daunomycin by HC-7-5 cells was about 70% that of HC-2-6 cells. By Northern blot analysis, using a multidrug-resistance gene (mdr-1) probe, neither HC-2-6 nor HC-7-5 expressed the mdr-1 gene, but HC-7-5/VCR or other multidrug-resistant variants showed active expression of the mdr-1 gene. Differential sensitivities among the five cell lines to 5-fluorouracil, cisplatinum, and bleomycin appear to be mediated through other mechanism beside the mdr-1 gene.

We have established three cell lines (IMC-2, IMC-3, and IMC-4) from a human maxillary tumor, which exhibited different sensitivities to epidermal growth factor (EGF). It was inhibitory to colony-forming abilities of IMC-3 and IMC-4 cells in culture, while it affected that of IMC-2 cells slightly if at all. The differential sensitivities to EGF among the three cell lines were reproducibly observed when several cell sublines were further established from tumors appearing in nude mice. Saturation-binding kinetics with 125I-EGF showed similar levels of EGF-binding activities among the three cell lines. However, IMC-2, IMC-3, and IMC-4 showed almost similar sensitivities to cisplatin. Autophosphorylation of EGF receptor in the presence of EGF proceeded at similar levels among the three cell lines. Tumor growth was followed in nude mice when IMC-2, IMC-3, and IMC-4 at 1 x 10(7) cells were inoculated. The IMC-2 tumors enlarged at much faster rates than the other two cell lines. The IMC-4 tumors showed very slow growth rates, and IMC-3 tumors enlarged at an intermediate rate. These data suggest that the maxillary tumor used comprised cell populations that differed in their growth behaviors in response to EGF.

No abstract

The triple combination of 5-fluorouracil (5-FU), vitamin A and radiation (FAR therapy) has been used since 1972 to treat malignant tumors of the head and neck at Kyushu University. Using nick end labeling of tumor specimens, cells of human maxillary sinus carcinomas were observed previously to undergo apoptosis in response to FAR therapy. The present study evaluated the in vitro effects of FAR therapy on a human maxillary sinus cancer (IMC-4) cell line. We further compared the effects of FAR therapy on this cell line with those effects seen on tissue samples taken from patients with maxillary sinus cancers. DNA electrophoresis and electron microscopic examination of the IMC-4 cells after treatment with FAR therapy revealed typical apoptotic features. The effects of 50-100 micrograms/ml 5-FU, 10(-4) M all-trans-retinoic acid and radiation to 6 Gy on IMC-4 cells were evaluated by trypan blue dye exclusion and a cell colony formation assay. 5-FU and radiation caused direct cell death, while vitamin A mainly inhibited cell growth. The combination of these treatment as FAR therapy synergistically enhanced cell death and inhibited cell growth. Flow cytometry demonstrated that FAR-treated cells were arrested in the G1 phase of the cell cycle before undergoing apoptosis. To further investigate possible biological parameters influencing a tumor's apoptotic sensitivity, we also examined the expression of p53 in human maxillary sinus cancer cells and analyzed the relationship between p53 expression and apoptosis. However, no relationship was found between these two markers at the time point studied.