Direct and indirect effects of human interferon alpha on renal cell carcinoma: a new in vitro assay system for evaluating cytokine-mediated antitumor effects

Differences in cell kinetic changes among renal cancer cell lines treated with interferon-alpha

BACKGROUND

Interferon (IFN)-alpha shows certain clinical effects on the treatment of renal cell carcinoma. The purpose of the present study was to investigate its direct effects and to compare the responses among different human renal cancer cell lines.

METHODS

Three cell lines, ACHN, RCC10RGB and OS-RC-2, were incubated with IFN-alpha and evaluated using MTT assay for cell proliferation and two-color flow cytometry for cell-cycle-specific cyclin expressions coupled with DNA ploidy analysis.

RESULTS

Interferon-alpha inhibited cell proliferation and caused cell accumulation at S and G2/M phases. However, IFN-alpha induced no significant change in cyclins D1, E, A or B1 expression. Interestingly, cell kinetic changes caused by IFN-alpha were different among cell lines. Cell proliferation was suppressed most in ACHN, then RCC10RGB and least in OS-RC-2. Comparing DNA histograms, ACHN showed distinct increase of G2/M cells associated with elevation of late S cells. RCC10RGB showed a predominant increase of whole S cells accompanied with a slight increase of G2/M. OS-RC-2 showed a modest increase of S cells with a little change of G2/M cells. Chronological observation revealed that S-phase increase and proliferative inhibition appeared on day 1 and day 3, respectively, in ACHN and RCC10RGB, and on day 5 in OS-RC-2.

CONCLUSIONS

Interferon-alpha induced substantial cell kinetic interference directly in the tested human renal carcinoma cell lines. The degree of change was different according to the nature of the cell line. It may partly indicate the variety of the efficacy of IFN-alpha treatment against renal cancers.

Efficacy of continuous subcutaneous infusion therapy using interferon alpha and the possible prognostic indicator of TNF-alpha in renal cell carcinoma

BACKGROUND

In an attempt to improve efficacy by escalating the dose and maintaining higher serum concentrations over a long period of time, this study examines continuous interferon alpha (IFN alpha) subcutaneous infusion therapy in patients with renal cell carcinoma (RCC).

METHODS

Seven of 11 patients with RCC had evaluable metastatic lesions. A highly purified natural human IFN alpha was injected subcutaneously via an infuser pump for 5 consecutive days, followed by a 2-day rest period (25 million IU/week). The treatment was continued for a period of 15 weeks. Serum concentrations of IFN alpha, IL-1 alpha, IL-1 beta, TNF-alpha, and IFN gamma were measured at intervals throughout the study period.

RESULTS

Two of the 7 patients with evaluable lesions achieved a partial response (overall response rate, 29%), while 1 achieved a partial response only to lung metastasis. These 3 cases were defined as responders. No difference was found in the concentration of serum IFN alpha between responders and nonresponders, however, a significantly higher concentration of serum TNF-alpha was observed in responders (P < 0.05, Mann-Whitney U test). Five cases (45%) had moderate to severe adverse effects, including depression (n = 1), eyeground hemorrhage (n = 2), and general fatigue (n = 2).

CONCLUSION

Appropriate patient selection may be necessary for subcutaneous continuous infusion therapy for the treatment of metastatic RCC. Also, the serum concentration of TNF-alpha measured during the course of treatment reflected well on the outcome of IFN alpha therapy.

Cytokine-mediated antitumor effect of bacillus Calmette-Guérin on tumor cells in vitro

Intravesical instillation therapy of bacillus Calmette-Guérin (BCG) is a useful modality for recurrent superficial transitional-cell carcinoma (TCC) of the urinary bladder. The mechanism of BCG effect has not yet been well characterized. BCG was tested in vitro for cytokine-mediated antiproliferative activity against T24 and KK47 cells (cell lines established from human TCC of the urinary bladder), and ACHN cells (cell line established from human renal cell carcinoma) using a modified human tumor clonogenic assay. Continuous exposure of cells to BCG at concentrations of more than 5 micrograms/ml in the presence of peripheral blood mononuclear cells (PBMC) consisting of a mixture of 5 x 10(4) monocytes/dish and 5 x 10(5) lymphocytes/dish, obtained from healthy donors, significantly inhibited colony formation of T24 and ACHN cells in comparison with growth inhibition in the absence of PBMC (P < 0.05). Slightly inhibited colony formation was observed with KK47 cells under the same conditions. At the same time various cytokines were measured in supernatants when BCG and the same conditioned PBMC were co-cultured. Tumor necrosis factor alpha (TNF alpha) and interleukin-1 beta (IL-1 beta) were detected at markedly high levels at 24 h, and interferon gamma (IFN gamma) was detected at 120 h. IL-2 and macrophage-colony-stimulating factor were not detected. Neutralizing anti-TNF alpha monoclonal antibody significantly reduced the anti-proliferative activity of ACHN cells, and anti-IFN gamma antibody reduced that of T24 cells. The results obtained suggest that cytokines mediated by BCG play an important role in the antitumor activity of BCG and that the sensitivity of bladder cancer cells to the cytokines induced by BCG may differ considerably.