Detection of bovine papillomavirus type 2 in the peripheral blood of cattle with urinary bladder tumours: possible biological role

Bovine papillomavirus type 2 (BPV-2) infection has been associated with urinary bladder tumours in adult cattle grazing on bracken fern-infested land. In this study, we investigated the simultaneous presence of BPV-2 in whole blood and urinary bladder tumours of adult cattle in an attempt to better understand the biological role of circulating BPV-2. Peripheral blood samples were collected from 78 cattle clinically suffering from a severe chronic enzootic haematuria. Circulating BPV-2 DNA was detected in 61 of them and in two blood samples from healthy cows. Fifty of the affected animals were slaughtered at public slaughterhouses and neoplastic proliferations in the urinary bladder were detected in all of them. BPV-2 DNA was amplified and sequenced in 78% of urinary bladder tumour samples and in 38.9% of normal samples as a control. Circulating episomal BPV-2 DNA was detected in 78.2% of the blood samples. Simultaneous presence of BPV-2 DNA in neoplastic bladder and blood samples was detected in 37 animals. Specific viral E5 mRNA and E5 oncoprotein were also detected in blood by RT-PCR and Western blot/immunocytochemistry, respectively. It is likely that BPV-2 can persist and be maintained in an active status in the bloodstream, in particular in the lymphocytes, as a reservoir of viral infection that, in the presence of co-carcinogens, may cause the development of urinary bladder tumours

Papillomavirus E5: the smallest oncoprotein with many functions

Papillomaviruses (PVs) are established agents of human and animal cancers. They infect cutaneous and mucous epithelia. High Risk (HR) Human PVs (HPVs) are consistently associated with cancer of the uterine cervix, but are also involved in the etiopathogenesis of other cancer types. The early oncoproteins of PVs: E5, E6 and E7 are known to contribute to tumour progression. While the oncogenic activities of E6 and E7 are well characterised, the role of E5 is still rather nebulous. The widespread causal association of PVs with cancer makes their study worthwhile not only in humans but also in animal model systems. The Bovine PV (BPV) system has been the most useful animal model in understanding the oncogenic potential of PVs due to the pivotal role of its E5 oncoprotein in cell transformation. This review will highlight the differences between HPV-16 E5 (16E5) and E5 from other PVs, primarily from BPV. It will discuss the targeting of E5 as a possible therapeutic agent

Acute kidney injury promotes development of papillary renal cell adenoma and carcinoma from renal progenitor cells.

Acute tissue injury causes DNA damage and repair processes involving increased cell mitosis and polyploidization, leading to cell function alterations that may potentially drive cancer development. Here, we show that acute kidney injury (AKI) increased the risk for papillary renal cell carcinoma (pRCC) development and tumor relapse in humans as confirmed by data collected from several single-center and multicentric studies. Lineage tracing of tubular epithelial cells (TECs) after AKI induction and long-term follow-up in mice showed time-dependent onset of clonal papillary tumors in an adenoma-carcinoma sequence. Among AKI-related pathways, NOTCH1 overexpression in human pRCC associated with worse outcome and was specific for type 2 pRCC. Mice overexpressing NOTCH1 in TECs developed papillary adenomas and type 2 pRCCs, and AKI accelerated this process. Lineage tracing in mice identified single renal progenitors as the cell of origin of papillary tumors. Single-cell RNA sequencing showed that human renal progenitor transcriptome showed similarities to PT1, the putative cell of origin of human pRCC. Furthermore, NOTCH1 overexpression in cultured human renal progenitor cells induced tumor-like 3D growth. Thus, AKI can drive tumorigenesis from local tissue progenitor cells. In particular, we find that AKI promotes the development of pRCC from single progenitors through a classical adenoma-carcinoma sequence

Mitophagy mediated by BNIP3 and BNIP3L/NIX in urothelial cells of the urinary bladder of cattle harbouring bovine papillomavirus infection.

Autophagy is a powerful tool that host cells use to defend against viral infection. Mitophagy, the selective autophagic removal of dysfunctional mitochondria was upregulated in urothelial cancer cells harbouring bovine papillomavirus (BPV) infection, as detected by the expression of BPV E5 protein, the major oncoprotein of bovine Deltapapillomavirus genus. HIF-1α-induced mitophagy receptors, BNIP3 and BNIP3L/Nix, were found to be overexpressed in these cells. The BNIP3 and BNIP3L/Nix receptors were amplified, and amplicon sequencing showed homology between bovine BNPI3 and BNIP3L/Nix sequences deposited in GenBank (accession number: NM_001076366.1 and NM_001034614.2, respectively). The transcripts and protein levels of BNIP3 and BNIP3L/Nix were significantly overexpressed in hypoxic neoplastic cells relative to healthy, non-neoplastic cells. BNIP3 and BNIP3L/Nix interacted with the LC3 protein, a marker of autophagosome (mitophagosome) membrane, ERAS, a small GTPase, and p62, known to be a specific autophagy receptor protein, that plays a role in mitochondrial priming for mitophagy and subsequent elimination. ERAS also interacted with the BPV E5 oncoprotein at mitochondrial level. Furthermore, in anti-Bag3 mitochondrial immunoprecipitates, a complex composed of the Hsc70/Hsp70 chaperone, CHIP co-chaperone, Synpo2, ERAS, LC3, p62, BNPI3, and BNIP3L/Nix was also detected. Bag3 may play a role in mitophagosome formation together with the Synpo2 protein and may be involved in the degradation of Hsc70/Hsp70-bound CHIP-ubiquitinated cargo, in association with its chaperone. ERAS may be involved in mitophagosome maturation via the PI3K signalling pathway. Ultrastructural findings revealed the presence of mitochondria exhibiting severe fragmentation and loss of cristae, as well as numerous mitochondria-containing autophagosomes