Detection of p73 antibodies in patients with various types of cancer: immunological characterization.

p53 antibodies have been found in the sera of patients with various types of cancer. The presence of these antibodies is generally associated with p53 accumulation in the tumour that is believed to trigger this humoral response. The recent discovery of 2 new members of the p53 family, p73 and p63, led us to study the specificity of this immune response towards the 3 proteins. Serum samples from 148 patients with various types of cancer were tested for antibodies against p73 and p63 using immunoprecipitation. 72 patients were previously shown to have p53 antibodies whereas 76 were negative. The control group consisted of 50 blood donors. p73 were detected in 22/148 (14.9%) of the cancer patients (11/72 in the group with p53-antibodies and 11/76 in the negative group). Only two sera from the control (4%) were positive. p63 antibodies were detected in only 4/148 (2.7%) of the cancer patients. Epitope mappings were performed and demonstrate that p73 antibodies are directed toward the central region of the p73 protein whereas p53 antibodies react predominantly toward the amino- and the carboxy-terminus of p53. Our results indicate that there is a specific immune response toward the p73 protein in cancer patients, a finding supported by an increasing number of publications describing p73 accumulation in tumoral cells.

P53 but not p16INK4a induces growth arrest in retinoblastoma-deficient hepatocellular carcinoma cells.

BACKGROUND/AIM: Both p16INK4a and p53 proteins are negative regulators of the cell cycle. In human hepatocellular carcinomas (HCC), the loss of function of p53, retinoblastoma (pRb) and pl6INK4a genes by different mechanisms has been largely documented, but their hepatocellular effects are poorly known. We compared the growth-inhibitory effects of p16INK4a and p53 proteins in Hep3B cell line-derived clones. METHODS: Cells were transfected with inducible p16INK4a and p53 expression vectors, and stable clones were analyzed for transgene expression by Western blotting and immunoperoxidase staining. Effects on cell growth were analyzed by in vitro growth assay, thymidine incorporation and flow cytometry. Biochemical effects of p53 were tested by Northern blotting of p21Cip1 transcripts and by Western blotting of p21Cip1, mdm-2, bax, cyclin-dependent kinase 2 and cyclin E proteins. The pRb protein was studied by Western blotting and immunoprecipitation assays. RESULTS: The induction of p16INK4a protein expression did not affect in vitro growth of cells. In contrast, p53 protein in its wild-type conformation provoked a growth arrest accompanied by transactivation of p21Cip1 gene and accumulation of p21Cip1, bax and mdm-2 proteins. p53-induced growth arrest was due to a cell cycle arrest at the G1/S transition, probably mediated by p21Cip1 protein, which inhibits cyclin-dependent kinase 2/cyclin E complexes. CONCLUSIONS: The lack of detectable pRb protein and resistance of cells to p16TNK4a strongly suggest that p53 is able to arrest the growth of HCC cells by a mechanism independent of "p53-retinoblastoma pathway". These findings are applicable to HCC with abberrations of both p53 and pRb genes, and may not represent the universal effects of p53 in hepatic cells.

A novel group of families of short interspersed repetitive elements (SINEs) in Xenopus: evidence of a specific target site for DNA-mediated transposition of inverted-repeat SINEs.

We have isolated from Xenopus borealis members of a family of short interspersed repetitive elements (SINEs) that we have termed Xbr. Xbr elements are also present in other Xenopus genomes and are typically framed by 46 bp terminal inverted repeats (TIRs). These TIRs and those of two previously described families of inverted-repeat SINEs from X. laevis begin with the sequence TTAAAGGRR. Knowledge of this consensus, termed the T2 motif, allowed us to define four previously uncharacterized families of inverted-repeat SINEs from Xenopus database sequences. We estimate that the group of seven SINE families that possess the T2 motif accounts for about 10% of all X. laevis SINEs. Novel evidence for the transposition of inverted-repeat SINEs is provided: (1) by examples of the presence/absence of T2 elements at corresponding locations in either duplicated genes or pseudotetraploid gene homeologues; and (2) by the existence of contiguous elements from different T2 families that are joined precisely by their TIRs. These examples provide novel evidence for a DNA-mediated mechanism of T2 element transposition. They also show that the tetranucleotide, TTAA, which flanks integrated elements on both sides and is present once at unoccupied sites, is the obligate target site for T2 insertion. The use of a specific sequence as a target site for SINE insertion is unexpected, although such specificity is exhibited by a limited number of larger transposable elements that encode their own transposase. The clear evidence for DNA-mediated transposition provided by T2 elements demonstrates that the evolution and maintenance of SINE families in vertebrate genomes results from two distinctive mechanisms.

Ultrasonic lithotripsy of bladder stones.

In the second half of 1985, 15 patients with 25 bladder stones were treated with Lutzeyer's Ultrasonic Lithotriptor. Of the patients 13 underwent additional operations, mostly transurethral resection of the prostate. The average duration of lithotripsy was 30.5 minutes. Some difficulties were experienced especially when drilling hard stones and as a complication late urethral bleeding occurred in one patient.