Resistance of mitochondrial p53 to dominant inhibition.

Background: Mutation of a tumor suppressor allele leaves the second as backup. Not necessarily so with p53. This homo-tetrameric transcription factor can become contaminated with mutant p53 through hetero-tetramerization.

Physical and functional interactions of human endogenous retrovirus proteins Np9 and rec with the promyelocytic leukemia zinc finger protein.

Only few of the human endogenous retrovirus (HERV) sequences in the human genome can produce proteins. We have previously reported that (i) patients with germ cell tumors often make antibodies against proteins encoded by HERV-K elements, (ii) expression of the HERV-K rec gene in transgenic mice can interfere with germ cell development and induce carcinoma in situ, and (iii) HERV-K np9 transcript is overproduced in many tumors including breast cancers. Here we document that both Np9 and Rec physically and functionally interact with the promyelocytic leukemia zinc finger (PLZF) tumor suppressor, a transcriptional repressor and chromatin remodeler implicated in cancer and the self-renewal of spermatogonial stem cells.

Np9 protein of human endogenous retrovirus K interacts with ligand of numb protein X.

We have recently identified Np9 as a novel nuclear protein produced by the human endogenous retrovirus K and were able to document the exclusive presence of np9 transcript in tumors and transformed cells. With the aim of studying whether Np9 has a role in tumorigenesis, a systematic search for interacting proteins was performed. Here, we identify the RING-type E3 ubiquitin ligase LNX (ligand of Numb protein X) as an Np9-interacting partner.

A novel gene from the human endogenous retrovirus K expressed in transformed cells.

Purpose: We investigated the expression of human endogenous retrovirus K (HERV-K) transcripts in various tumor tissues and transformed cell lines.

Experimental Design: We performed reverse transcription-PCR analysis to examine expression of env reading frame transcripts in mammary carcinoma biopsies, germ-cell tumor samples, ovarian carcinomas, and lymphocytes of leukemic patients, as well as in a variety of transformed cell lines. The novel np9 gene was analyzed by sequencing.