The identification of Mouse Mammary Tumour Virus (MMTV) as the causal factor for breast cancer in mice, initiated investigation into a viral cause for human breast cancer. MMTV-like virus has been detected in human breast cancers, lymphomas and primary biliary cirrhosis (PBC), suggesting the virus is not restricted to human breast cancers. We hypothesized that the virus is detected in human tissues influenced by steroid hormones. We detected a region of the envelope (env) gene of MMTV-like virus in 53/210 (25%) of liver disease, 4/21 (19%) of hepatocellular carcinoma (HCC), 14/89 (16%) of ovarian cancer, 53/147 (36%) of prostate cancer, 5/50 (10%) of endometrial cancer and 13/141 (9%) of skin cancer samples but not in lung cancers (0/51). Viral env DNA was also detected in 4/81 (5%) of placentae and 5/90 (6%) of breast milk cells from healthy women whilst viral env RNA was detected in 2/90 (2%) of breast milk supernatants and (0/81) placentae. Immunohistochemistry staining for the presence of estrogen receptor alpha (ER-??) and progesterone receptor (PgR) demonstrated a significant association between ER-??/PgR and MMTV-like virus in human ovarian, prostate, endometrial and skin cancers though no significant association was observed between ER-??/PgR and the virus in liver tissues. We were also unable to demonstrate a significant association between accumulation of p53 tumour suppressor protein and MMTV-like virus in liver disease and HCC. Despite the demonstration of viral env integration in genomic DNA from human placentae using Southern Blots, other regions of the virus were not detected following PCR attempts with published primer sets. This study adds to the current knowledge of distribution of MMTV-like virus in humans. The detection of the virus in hormonally influenced human tissues (positive for ER-?? or PgR) indicates an association between MMTV-like virus and steroid hormones in some human tissues. The detection of the virus in placentae and breast milk also suggests potential routes of transmission of the virus in humans. Although the exact role of the virus in these tissues is not known, the presence of the virus together with other genetic alterations and/or the influence of steroid hormones could be involved in the transformation of various human tissues (i.e.pathogenesis).

Proefschrift Universiteit van Amsterdam. / Met samenvatting in het Nederlands.

Diss. (sammanfattning) Uppsala : Univ., 2001. / Härtill 4 uppsatser.

Thesis (Ph. D., Microbiology, Molecular Biology and Biochemistry)--University of Idaho, August 2006. / Major professor: Elizabeth A. Fortunato. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.

Thesis (Ph. D.)--University of Hong Kong, 1998. / Includes bibliographical references (leaf 147-169).

University, Diss., 2004--München.

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisor: John H. Richburg. Vita. Includes bibliographical references.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 177-202). Also available in electronic version.

The p53 protein plays a central role in controlling the fate of cancer cells. At moderate levels of DNA damage, the concentration of the phosphorylated form of p53 undergoes temporal oscillation with a period of a few hours. In Dr. Shi’s lab, single-cell measurements were carried out using the p53-YFP fusion proteins and time-lapse fluorescence microscopy. We report here a detailed study of the image data. From the time series of the p53 concentration in individual cells, we deduce the amplitude and period of the oscillation. The pulse-to-pulse and cell-to-cell variability of the oscillation is characterized. We then carry out a computational study of a mathematical model that involves a negative feedback loop between p53 and Mdm2 proteins. We have determined the phase diagram of the model, and studied the sensitivity of the properties of the oscillating state against the model parameters. Although only p53 concentration is measured in the experiment, we show that careful analysis of the pulse shape can nevertheless yield valuable information on the underlying molecular processes, and shed light on the possible origin of the observed cellto- cell variations.

Les anomalies de TP53, que sont la délétion génique associée ou non à des mutations somatiques, demeurent un facteur de résistance au traitement dans le Myélome Multiple (MM) malgré l’introduction de nouveaux agents thérapeutiques. Pour contourner les anomalies de TP53, nous avons étudié la possibilité d’activer p73, un membre de la famille de p53, qui n’est pas fréquemment muté dans les cancers. Nous avons étudié l’expression, la méthylation et la régulation de TP73 dans une collection de lignées de MM sauvages ou déficientes pour p53. Nous montrons que TP73 est rarement exprimé et surtout dans les lignées TP53 sauvage. Nous avons étudié la méthylation de l’ilot CpG situé en amont du gène par MS-PCR et montré que l’absence d’expression correspond à son hyperméthylation, qui peut néanmoins être réversée par la décitabine, un inhibiteur de la méthylation. Malgré l’augmentation d’expression de TP73, la décitabine ne permet pas une expression protéique significative de p73. Pour étudier la régulation de p73, nous avons utilisé des agents alkylants, des inhibiteurs de MDM2 et du protéasome. Nous montrons que les nutlin3a et MG132, ne stabilisent pas p73 mais diminuent son expression constitutive. Les agents alkylants induisent une augmentation de p73 mais uniquement dans les lignées TP53 sauvage et l’extinction de p53 par ARN interférence inhibe cette régulation. Dans les lignées déficientes pour p53, la décitabine augmente l’expression génique mais le melphalan ne permet pas de stabilisation de la protéine. L’ensemble de nos résultats montre que TP73 n’apparaît pas être un bon candidat pour contourner les anomalies de TP53. / TP53 deficiency remains a major adverse event in Multiple Myeloma despite therapeutic progresses. p73, a member of p53 family, is very rarely mutated and has been poorly studied in myeloma. Using human myeloma cell lines with different TP53 status, we assessed methylation, expression and regulation of TP73. We report that TP73 is silenced by methylation and that decitabine increases its expression, which remains however insufficient for significant protein expression. Alkylating drugs increase expression of TP73 only in TP53wt cells and fail to synergize with decitabine in p53 deficient cells. On the other hand, MG132 and nutlin-3a don’t stabilize p73 in response to in TP53wt p73 positive cell lines. TP73 does not appear as a promising target for bypassing p53 deficiency in Multiple Myeloma.