Showing papers by "Walter M. Stadler published in 1999"

Mitogen-activated Protein Kinase Kinase 4/Stress-activated Protein/Erk Kinase 1 (MKK4/SEK1), a Prostate Cancer Metastasis Suppressor Gene Encoded by Human Chromosome 17

Abstract: The introduction of a discontinuous approximately 70-cM portion of human chromosome 17 significantly suppresses the metastatic ability of AT6.1 rat prostate cancer cells without affecting tumorigenicity (M. A. Chekmareva et al., Prostate, 33: 271-280, 1997). We have recently demonstrated that AT6.1 cells containing the approximately 70-cM region (AT6.1-17-4 cells) escape from the primary tumor and arrest in the lung but are growth-inhibited unless the metastasis suppressor region is lost (M. A. Chekmareva et al., Cancer Res., 58: 4963-4969, 1998). A series of in vivo studies indicated that the observed growth inhibition was due to the effect of a gene(s) at the metastatic site (M. A. Chekmareva et al., Cancer Res., 58: 4963-4969, 1998). We have now identified the mitogen-activated protein kinase kinase 4/stress-activated protein/Erk kinase 1 (MKK4/SEK1) gene as a candidate metastasis suppressor gene encoded by the approximately 70-cM region. AT6.1 cells were transfected with a MKK4/SEK1 expression construct, and the cells were tested in standard spontaneous metastasis assays. Whereas the metastatic ability of the AT6.1-MKK4/SEK1 cells was significantly reduced as compared with that of transfection controls, the growth rate of the primary tumors was not affected; the average tumor volume at day 29 after injection was approximately 2 cm. Furthermore, histological examination of the lungs of AT6.1-MKK4/SEK1 tumor-bearing animals revealed that the suppression by MKK4/SEK1 is due to an effect at the metastatic site, consistent with the phenotype conferred by the original approximately 70-cM chromosomal region. These studies implicate MKK4/SEK1 as a metastasis suppressor gene encoded by human chromosome 17.

Multi-Institutional Study of the Angiogenesis Inhibitor TNP-470 in Metastatic Renal Carcinoma

Abstract: PURPOSE: Renal cell carcinoma is resistant to most chemotherapy, and only a minority of patients respond to immunotherapy. Its highly vascular nature suggests that antiangiogenesis therapy might be useful. We thus performed a phase II study of the fumigillin analog TNP-470 in previously treated patients with metastatic renal cell carcinoma. PATIENTS AND METHODS: Metastatic renal cell carcinoma patients with good organ function were entered onto the study through five separate institutions. There were no exclusion criteria for prior therapy. All patients were treated at a dose of 60 mg/m2 of TNP-470 infused over 1 hour three times per week. RESULTS: Thirty-three patients were enrolled. Therapy was generally well tolerated, but asthenia, fatigue, vertigo, dizziness, sense of imbalance, and loss of concentration were common and severe enough to lead to therapy discontinuation in five patients. There was only one partial response of short duration (response rate, 3%, 95% confidence interval, 0% to 16%), but s...

In vitro evaluation of flavopiridol, a novel cell cycle inhibitor, in bladder cancer.

Abstract: Purpose: To determine the in vitro effects of flavopiridol on bladder cancer cell lines, immortalized urothelial cell lines, and normal urothelial cells well characterized for defects in p53, pRb, and p16. Methods: Growth inhibition was assessed via an MTT assay and apoptosis via DAPI nuclear staining. Cell cycle analysis was performed via propidium iodide staining and fluorescent activated cell sorting (FACS). Multidrug-resistant cells were generated by continuous exposure to doxorubicin. Results: Growth inhibition was not correlated with inactivation of p53, pRb, or p16. All cells experienced G2/M arrest within 24 h of flavopiridol exposure. Modest apoptosis was observed but required 72 h of continuous drug exposure to become evident. There was no obvious synergistic or antagonistic toxicity when flavopiridol was combined with radiotherapy or cisplatin dosed at the IC50 despite the observation that radiotherapy and flavopiridol led to more profound G2/M arrest than either agent alone. Doxorubicin-resistant cells, demonstrated to overexpress the MDR1 multidrug-resistance protein were equally as sensitive to flavopiridol as the parental cells. Conclusions: Flavopiridol is a novel cell cycle inhibitor that may be a useful agent in bladder cancers with tumor suppressor gene alterations and/or multidrug resistance.