Bovine Papillomaviruses (BPVs) constitute a diverse group within the Papillomaviridae family, playing a crucial role in bovine health and economic considerations. This study investigates the dynamics of vertical transmission of BPV in cattle, focusing on five cows and their reproductive tissues, as well as three gravid cows and their fetuses. DNA and RNA samples were extracted from the warts, fetal skin, placenta, uterus, ovary, and blood of cows, as well as the skin and blood of fetuses. Polymerase Chain Reaction (PCR) targeted BPV types 1-6 and 8-14, was assessed in both cows and fetuses. Additionally, Reverse Transcription PCR (RT-PCR) examined BPV-2 E5 oncogene expression in the skin and reproductive sites of mother cows and fetuses. Our findings unveil a rich diversity of BPV types, including BPV-2, 3, 9, 10, 12, and 14, present in both maternal and fetal tissues. Intriguingly, certain types, namely BPV-4, 6, 8, and 11, were exclusively identified in maternal tissues A higher diversity of BPVs was observed in cow warts, followed by cow blood, fetal blood, and fetal skin. Strikingly similar BPV types in gravid cow blood and fetuses suggest primary dissemination through the bloodstream and transmission via the placenta, though detected in lower numbers in cow uterus and ovary. Histopathological analysis revealed no abnormalities in the reproductive tissues despite the presence of BPV. However, in one bladder sample from a cow that did not consume bracken fern, urothelial neoplasia in situ was observed. The study extends beyond detection, exploring the expression of the BPV-2 E5 oncogene in fetal tissues, providing insights into potential cell implications. Comparative analyses with previous studies highlight the uniqueness of our investigation, encompassing a broader array of BPV types in the gravid cows and their fetuses. The findings not only establish a foundation for further investigations into the mechanisms of vertical transmission but also highlight the need for targeted interventions and surveillance strategies to mitigate potential health risks associated with specific BPV types.

The integration of HPV DNA into human chromosomes plays a pivotal role in the onset of papillomavirus-related cancers. HPV DNA integration often occurs by linearizing the viral DNA in the E1/E2 region, resulting in the loss of a critical viral early polyadenylation signal (PAS), which is essential for the polyadenylation of the E6E7 bicistronic transcripts and for the expression of the viral E6 and E7 oncogenes. Here, we provide compelling evidence that, despite the presence of numerous integrated viral DNA copies, virus-host fusion transcripts originate from only a single integrated HPV DNA in HPV16 and HPV18 cervical cancers and cervical cancer-derived cell lines. The host genomic elements neighboring the integrated HPV DNA are critical for the efficient expression of the viral oncogenes that leads to clonal cell expansion. The fusion RNAs that are produced use a host RNA polyadenylation signal downstream of the integration site, and almost all involve splicing to host sequences. In cell culture, siRNAs specifically targeting the host portion of the virus-host fusion transcripts effectively silenced viral E6 and E7 expression. This, in turn, inhibited cell growth and promoted cell senescence in HPV16+ CaSki and HPV18+ HeLa cells. Showing that HPV E6 and E7 expression from a single integration site is instrumental in clonal cell expansion sheds new light on the mechanisms of HPV-induced carcinogenesis and could be used for the development of precision medicine tailored to combat HPV-related malignancies.
OBJECTIVE: Persistent oncogenic HPV infections lead to viral DNA integration into the human genome and the development of cervical, anogenital, and oropharyngeal cancers. The expression of the viral E6 and E7 oncogenes plays a key role in cell transformation and tumorigenesis. However, how E6 and E7 could be expressed from the integrated viral DNA which often lacks a viral polyadenylation signal in the cancer cells remains unknown. By analyzing the integrated HPV DNA sites and expressed HPV RNAs in cervical cancer tissues and cell lines, we show that HPV oncogenes are expressed from only one of multiple chromosomal HPV DNA integrated copies. A host polyadenylation signal downstream of the integrated viral DNA is used for polyadenylation and stabilization of the virus-host chimeric RNAs, making the oncogenic transcripts targetable by siRNAs. This observation provides further understanding of the tumorigenic mechanism of HPV integration and suggests possible therapeutic strategies for the development of precision medicine for HPV cancers.

Cervical cancer is the fourth most frequent cancer in women worldwide and a major cause of mortality in developing countries. Persistent infection with high-risk human papillomavirus (HPV) is a necessary cause for the development of cervical cancer. In addition, genetic and epigenetic alterations in host cell genes are crucial for progression of cervical precancerous lesions to invasive cancer. Although much progress has been made in understanding the life cycle of HPV and it\'s role in the development of cervical cancer, there is still a critical need for accurate surveillance strategies and targeted therapeutic options to eradicate these cancers in patients. Given the widespread nature of HPV infection and the type specificity of currently available HPV vaccines, it is crucial that molecular details of the natural history of HPV infection as well as the biological activities of viral oncoproteins be elucidated. A better understanding of the mechanisms involved in oncogenesis can provide novel insights and opportunities for designing effective therapeutic approaches against HPV-associated malignancies. In this review, we briefly summarize epigenetic alterations and events that cause alterations in host genomes inducing cell cycle deregulation, aberrant proliferation and genomic instability contributing to tumorigenesis.

The integration of HR-HPV genome into host DNA is regarded as a key step for the development of cervical cancer. However, HR-HPV genome indeed exists as episome except for integrant. It may be alternative mechanisms in episome-associated carcinogenesis, although, by which HPV 16 episome induces cervical carcinogenesis is unclear now.
Ninety-three invasive cervical cancer tissues with HPV16 positive were collected. Viral physical status was calculated from comparing E2 to E6-copies and detection of viral load was made with realtime-PCR using copy numbers of E6. HPV16 E6 mRNA transcript levels were measured by realtime-PCR. The methylation frequency of HPV16 promoter was detected by PCR and pyrosequencing.
In 93 samples, 21.5% (20/93) presented purely integrated viral genome, 53.8% (50/93) mixed viral genome, and 24.7% (23/93) purely episomal viral genome. Mean E6 expression in samples with purely episomal viral genomes was 7.13-fold higher than that with purely integrated viral genomes. Meanwhile, viral load in samples with purely episomal viral genomes was 4.53-fold higher than that with purely integrated viral genomes. E6 mRNA expression increased with the viral load in purely episomal cases. There were no differences of mean methylation frequency between purely episomal and integrated virus and among five CpG positions of HPV16 promoter for all samples. And there also was no correlation between E6 mRNA expression and methylation of HPV16 promoter among all samples with purely HPV16 episomal virus.
HPV16 with the purely episomal viral genomes exists in a definite proportion of invasive cervical cancer, and episomal HPV16 also overexpresses E6 mRNA, probably through a high level of viral load.

Oncogene expression can lead to replication stress and genome instability. Recently, we identified oncogene-induced fragile sites (FSs) and revealed that the landscape of recurrent fragility in the same cell type is dynamic. This implies an additional level of complexity in the molecular basis of recurrent fragility in cancer.

Chromosomal instability in early cancer stages is caused by replication stress. One mechanism by which oncogene expression induces replication stress is to drive cell proliferation with insufficient nucleotide levels. Cancer development is driven by alterations in both genetic and environmental factors. Here, we investigated whether replication stress can be modulated by both genetic and non-genetic factors and whether the extent of replication stress affects the probability of neoplastic transformation. To do so, we studied the effect of folate, a micronutrient that is essential for nucleotide biosynthesis, on oncogene-induced tumorigenicity. We show that folate deficiency by itself leads to replication stress in a concentration-dependent manner. Folate deficiency significantly enhances oncogene-induced replication stress, leading to increased DNA damage and tumorigenicity in vitro. Importantly, oncogene-expressing cells, when grown under folate deficiency, exhibit a significantly increased frequency of tumor development in mice. These findings suggest that replication stress is a quantitative trait affected by both genetic and non-genetic factors and that the extent of replication stress plays an important role in cancer development.

Myeloid/lymphoid or mixed-lineage AF4 acute lymphoblastic leukemia (MLL-AF4 ALL) is a pediatric leukemia that occurs rarely in adults. MLL-AF4 ALL is typically characterized by the presence of chromosomal translocation (t(4;1l)(q21;q23)), leading to expression of MLL-AF4 fusion protein. Although MLL-AF4 fusion protein triggers a molecular pathogenesis and hematological presentations that are unique to leukemias, the precise role of this oncogene in leukemogenesis remains unclear. Previous studies have indicated that microRNAs (miRs) might modulate the expression of MLL-AF4 ALL fusion protein, thereby suggesting the involvement of miR in progression or suppression of MLL-AF4 ALL. We have previously demonstrated that miR-205 negatively regulates transcription of an MLL-AF4 luciferase reporter. Here, we report that exogenous expression of miR-205 in MLL-AF4 human cell lines (RS4;11 and MV4-11) inversely regulates the expression of MLL-AF4 at both messenger RNA (mRNA) and protein level. Furthermore, miR-205 significantly induced apoptosis in MLL-AF4 cells as evidenced by Annex in V staining using fluorescence-activated cell sorting (FACS) analysis. The proliferative capacity of leukemic cells was suppressed by miR-205. The addition of an miR-205 inhibitor was able to restore the observed effects. In conclusion, these findings demonstrate that miR-205 may have potential value as a novel therapeutic agent in the treatment of MLL-AF4 ALL.