Human papillomavirus E7 binds Oct4 and regulates its activity in HPV-associated cervical cancers.

Octamer binding transcription factor-4 (Oct4), is highly expressed in stem cells and has indispensable roles in pluripotency and cellular reprogramming. In contrast to other factors used for cellular reprogramming, a role for Oct4 outside embryonic stem cells has been elusive and highly controversial. Emerging evidence implicates Oct4 in the carcinogenic process, but the mechanism through which Oct4 may be functioning in cancers is not fully appreciated. Here, we provide evidence that Oct4 is expressed in human cervical cancer and this expression correlates with the presence of the human papillomavirus (HPV) oncogenes E6 and E7. Surprisingly, the viral oncogenes can complement exogenously provided Oct4 in reprogramming assays, providing functional validation for their ability to activate Oct4 transcription in Mouse Embryonic Fibroblasts (MEFs). To interrogate potential roles of Oct4 in cervical cancers we knocked-down Oct4 in HPV(+) (HeLa & CaSki) and HPV(-) (C33A) cervical cancer cell lines and found that Oct4 knockdown attenuated clonogenesis, only in the HPV(+) cells. More unexpectedly, cell proliferation and migration, were differentially affected in HPV(+) and HPV(-) cell lines. We provide evidence that Oct4 interacts with HPV E7 specifically at the CR3 region of the E7 protein and that introduction of the HPV oncogenes in C33A cells and human immortalised keratinocytes generates Oct4-associated transcriptional and phenotypic patterns, which mimic those seen in HPV(+) cells. We propose that a physical interaction of Oct4 with E7 regulates its activity in HPV(+) cervical cancers in a manner not seen in other cancer types.

NAA40 contributes to colorectal cancer growth by controlling PRMT5 expression.

N-alpha-acetyltransferase 40 (NAA40) catalyzes the transfer of an acetyl moiety to the alpha-amino group of serine 1 (S1) on histones H4 and H2A. Our previous studies linked NAA40 and its corresponding N-terminal acetylation of histone H4 (N-acH4) to colorectal cancer (CRC). However, the role of NAA40 in CRC development was not investigated. Here, we show that NAA40 protein and mRNA levels are commonly increased in CRC primary tissues compared to non-malignant specimens. Importantly, depletion of NAA40 inhibits cell proliferation and survival of CRC cell lines and increases their sensitivity to 5-Fluorouracil (5-FU) treatment. Moreover, the absence of NAA40 significantly delays the growth of human CRC xenograft tumors. Intriguingly, we found that NAA40 knockdown and loss of N-acH4 reduce the levels of symmetric dimethylation of histone H4 (H4R3me2s) through transcriptional downregulation of protein arginine methyltransferase 5 (PRMT5). NAA40 depletion and subsequent repression of PRMT5 results in altered expression of key oncogenes and tumor suppressor genes leading to inhibition of CRC cell growth. Consistent with this, NAA40 mRNA levels correlate with those of PRMT5 in CRC patient tissues. Taken together, our results establish the oncogenic function of the epigenetic enzyme NAA40 in colon cancer and support its potential as a therapeutic target.

Terc is dispensable for most of the short-term HPV16 oncogene-mediated phenotypes in mice.

High-risk human papillomaviruses (HPVs) have been shown in vitro to impinge on telomere homeostasis in a number of ways. However, the in vivo interaction of viruses with the telomere homeostasis apparatus has not been previously explored. Since E6 and E7 are the main viral oncogenes and key for viral replication, we have explored here the short-term phenotypes of the genes in the context of defective telomere homeostasis. We examined the short-term phenotypes of E6 and E7 in a context where the Terc component of the telomerase holoenzyme was knocked out. We determined that Terc was dispensable for most oncogene-mediated phenotypes. Surprisingly, E7-mediated reduction of label retaining cells was found to be in part dependent on the presence of Terc. Under the conditions examined here, there appears to be no compelling evidence Terc is required for most short-term viral oncogene mediated phenotypes. Further studies will elucidate its role in longer-term phenotypes.

Inflammation Shapes Stem Cells and Stemness during Infection and Beyond.

The outcome of an inflammatory incident can hang in the balance between restoring health and tissue integrity on the one hand, and promoting aberrant tissue homeostasis and adverse outcomes on the other. Both microbial-related and sterile inflammation is a complex response characterized by a range of innate immune cell types, which produce and respond to cytokine mediators and other inflammatory signals. In turn, cells native to the tissue in question can sense these mediators and respond by migrating, proliferating and regenerating the tissue. In this review we will discuss how the specific outcomes of inflammatory incidents are affected by the direct regulation of stem cells and cellular plasticity. While less well appreciated than the effects of inflammatory signals on immune cells and other differentiated cells, the effects are crucial in understanding inflammation and appropriately managing therapeutic interventions.

Shared mechanisms in stemness and carcinogenesis: lessons from oncogenic viruses.

A rise in technologies for epigenetic reprogramming of cells to pluripotency, highlights the potential of understanding and manipulating cellular plasticity in unprecedented ways. Increasing evidence points to shared mechanisms between cellular reprogramming and the carcinogenic process, with the emerging possibility to harness these parallels in future therapeutics. In this review, we present a synopsis of recent work from oncogenic viruses which contributes to this body of knowledge, establishing a nexus between infection, cancer, and stemness.

Molecular characterization of HIV type 1 strains from newly diagnosed patients in Cyprus (2007-2009) recovers multiple clades including unique recombinant strains and lack of transmitted drug resistance.

HIV-1 evolution generates substantial genetic diversity among isolates, the majority of which are represented in areas where multiple strains cocirculate. A heterogeneous genetic HIV-1 pool has been found in Cyprus, directing us to determine the dynamics of the local HIV-1 infection by characterizing strains isolated from 74 subjects during 2007-2009, representing 88% of the known-living HIV-1-infected population, of whom 53 are newly diagnosed therapy-naive patients and 21 are chronic patients, according to the European HIV Resistance guidelines. Near full-length genome sequences were amplified by RT-nested PCR using diluted RNA from all HIV-1 seropositives and sequenced using a newly designed assay. Resistant mutations were not found among the population of the newly diagnosed therapy-naive patients either to protease, reverse transcriptase, or integrase inhibitors. Phylogenetic analyses indicated subtype B as the main subtype (48.6%), followed by subtype A (18.9%), subtype C (10.8%), CRF02_AG (8.1%), CRF11_cpx (2.7%), and (sub)subtype F1 and CRF37_cpx (1.4% each). Six HIV-1 isolates (8.1%) were not classified in any pure (sub)subtype or circulating recombinant form (CRF). Complete phylogenetic and bootscanning analyses revealed that each isolate had a new, unique recombinant pattern and is distinct from all other CRFs or unique recombinant forms (URFs) reported so far. Two of the six isolates have the same mosaic pattern. Analogous to results of the earlier epidemiological studies, this study expands on the HIV-1 sequence database and reveals the high degree of diversity of HIV-1 infection in Cyprus.

Determination of antigenic properties of vaccine derived poliovirus strains.

In this study, the immunity level of the southern Greek population in the 1-10-year, 11-20-year, 21-30-year and 31-40-year age groups with regard to Sabin vaccine strains and a collection of 11 recombinant and three non-recombinant poliovirus vaccine strains was determined. The results showed the lowest neutralization titre in the 21-30-year-age group against poliovirus type 3. Moreover, the capsid coding region of OPV (oral poliovirus vaccine) derivatives was sequenced in order to identify mutations that might lead to antigenic changes. In Sabin-1 derivatives a tendency of accumulation of mutations was observed in or near antigenic sites while in Sabin-2 and Sabin-3 derivatives in sites known to be involved in restoring neurovirulence or eliminating their temperature-sensitive phenotype. It was concluded that the combination of mutations in the capsid coding region and not the number of specific mutations in antigenic sites determines the antigenic properties of OPV derivatives and their reactivity with human sera.