The development and progression of thyroid tumors is signaled by phenotype-specific mutations of genes involved in growth control. Molecular events associated with undifferentiated thyroid cancer are not known. We examined normal, benign, and malignant thyroid tissue for structural abnormalities of the p53 tumor suppressor gene. Mutations were detected by singlestrand conformation polymorphisms of PCR-amplified DNA, using primers bracketing the known hot spots on either exons 5, 6, 7, or 8. The prevalence of mutations was as follows: normal thyroid 0/6; follicular adenomas 0/31; papillary carcinomas 0/37; medullary carcinomas 0/2; follicular carcinomas 1/11; anaplastic carcinomas 5/6; thyroid carcinoma cell lines 3/4. Positive cases were confirmed by direct sequencing of the PCR products. All five anaplastic carcinoma tissues and the anaplastic carcinoma cell line ARO had G:C to A:T transitions leading to an Arg to His substitution at codon 273. In both tumors and cell lines, examples of heterozygous and homozygous p53 mutations were identified. The only thyroid carcinoma cell line in which p53 mutations were not detected in exons 5-8 had markedly decreased p53 mRNA levels, suggesting the presence of a structural abnormality of either p53 itself or of some factor controlling its expression. The presence of p53 mutations almost exclusively in poorly differentiated thyroid tumors and thyroid cancer cell lines suggests that inactivation of p53 may confer these neoplasms with aggressive properties, and further loss of differentiated function. (J. Clin. Invest. 1993. 91:179-184.)

BACKGROUND Management of prostate cancer that has spread outside of the prostate capsule is a difficult problem. Innovative, non‐toxic approaches to the disease are required. New, relatively non‐toxic vitamin D3 analogs have recently been synthesized. We report that several of these compounds have marked antiproliferative effects on prostate cells. METHODS The clonal antiproliferative activity of five novel analogs of 1,25 dihydroxyvitamin D3 [1,25(OH)2D3, (cmpd C)] as well as 1,25(OH)2D3 itself was tested on three human prostate cancer cell lines (PC‐3, LNCaP, and DU‐145). The analogs were 20‐epi‐22oxa‐24a,26a,27a‐tri‐homo‐1α,25(OH)2D3 (code name: KH 1060); 24a26a27a‐tri‐homo‐22,24‐dienelα,25(OH)2D3 (code name: EB 1089); 1,25(OH)2‐16ene‐D3 (code name: HM); 1,25(OH)2‐16ene‐23yne‐D3 (code name: V); 1,25(OH)2‐20‐epi‐D3 (code name: MC 1288)]. RESULTS With the parent compound [1,25(OH)2D3], the effective dose that inhibited 50% clonogenic growth of PC‐3 and LNCaP was 10−8M and 7 x 10−9 M, respectively. For these prostate cancer cell lines, KH 1060 was the most potent analog by an order of 25‐ to 35‐fold as compared to cmpd C. The second and third most potent analogs were HM and MC 1288. DU‐145 was resistant to all the vitamin D3 analogs. The major side‐effect of 1,25(OH)2D3 is the production of hypercalcemia. The relative inhibitory index (RII) was determined by comparing the antiproliferative activity of the analog to its ability to produce hypercalcemia in mice injected intraperitoneally every other day. The KH 1060 had the best RTI: 50‐ to 70‐fold greater than 1,25(OH)2D3 for PC‐3 and LNCaP, respectively. CONCLUSIONS A trial of one or more of these innovative compounds should be considered for treatment of minimal residual disease of prostate cancer. Prostate 31:77–83, 1997. © 1997 Wiley‐Liss, Inc.

The human ets-2 proto-oncogene is one of the homologs of the v-ets gene, found in avian acutely transforming retrovirus E26 (D. Leprince, A. Gegonne, J. Call, C. de Taisne, A. Schneeberger, C. Lagrou, and D. Stehelin, Nature [London] 306:395-397, 1983; M. F. Nunn, P. H. Seeburg, C. Moscovici, and P. H. Duesberg, Nature [London] 306:391-395, 1983), which causes leukemia in chickens. We used the DNA-binding domain of yeast transcriptional activator GAL4 to locate the transactivation region of human ets-2. The transactivation domain of ets-2 was found in the N-terminal part of the protein, which is homologous to ets-1, and can be disrupted by deletion of a stretch of acidic amino acid residues. A transactivation-deficient mutant of ets-2 failed to transform Rat-1 cells and suppressed the transforming activity of coexpressed wild-type ets-2. A mutation in the putative DNA-binding region of ets-2 abolished transforming activity. We show that the motif crucial for ets-2 transactivation capability is necessary for transforming activity in Rat-1 cells. Mutant ets-2 protein that lacks the transactivation domain has a dominant negative effect on transformation by wild-type ets-2. We were unable to detect ets-2-dependent transcriptional regulation of several enhancers containing ets-binding motifs.