FeLV integration in human cells: cancer genes and active chromatin regions
PloS one · 2016
In plain language
This laboratory study examined where FeLV integrates into the DNA of human cells. The main integration targets were enriched for genes listed as cancer-related, but this does not show that the insertions caused cancer or altered those genes. Integration also strongly favored regions of active chromatin, with no significant selection for cell growth detected after integration. These results do not establish what happens in feline cells or cats.
Scientific detail
The study, published in PloS one in 2016, examined FeLV integration in human cells in vitro. The supplied object does not report the sample size or list stated study limitations. All three findings have evidence level D.
The most prominent FeLV integration targets showed little overlap with the most abundantly expressed transcripts but were strongly enriched for annotated cancer genes. This enrichment concerns the human-cell analysis and does not demonstrate that the insertions caused cancer or altered the targeted genes.
In human MCF-7 mammary carcinoma cells, FeLV insertion sites showed a strong bias towards active chromatin marks, with no evidence of significant post-integration growth selection. Failure to detect significant growth selection does not establish its absence, and this finding does not establish integration preferences in cats.
A meta-analysis of gamma-retrovirus integration profiling studies in human CD34+, K562 and HepG2 cells reported cancer gene bias and cell-type specificity, with a shared integration hotspot at MALAT1. The supplied text does not establish that every included study used FeLV or that MALAT1 is a shared integration hotspot in feline cells. Together, these data inform FeLV integration biology but do not establish integration preferences, insertional oncogenesis or growth selection in feline cells or cats.
What we know
Evidence at level D describes enrichment for cancer genes among prominent FeLV integration targets in human cells and a bias towards active chromatin marks in MCF-7 cells, with no significant post-integration growth selection detected. The human-cell gamma-retrovirus meta-analysis describes cancer gene bias, cell-type specificity and a shared integration hotspot at MALAT1.
What we don't know
The supplied text does not establish whether these insertions caused cancer or altered the targeted genes, and it cannot rule out growth selection. It also does not establish these integration patterns, insertional oncogenesis or growth selection in feline cells or cats, or that every study in the meta-analysis used FeLV. The object does not report the sample size or list stated limitations.
Evidence
EvidenceLevel D — Indirect evidence: other species or retrovirusConfidence 100/100
The most prominent FeLV integration targets showed little overlap with the most abundantly expressed transcripts but were strongly enriched for annotated cancer genes.
Excerpt verified in the source — verbatim, in the source's own language“The most prominent FeLV integration targets had little overlap with the most abundantly expressed transcripts, but were strongly enriched for annotated cancer genes.”
The reported enrichment concerns integration targets in the human-cell analysis. It does not demonstrate that these insertions caused cancer or altered the targeted genes.
EvidenceLevel D — Indirect evidence: other species or retrovirusConfidence 100/100
FeLV insertion sites in human MCF-7 mammary carcinoma cells showed a strong bias towards active chromatin marks, with no evidence of significant post-integration growth selection.
Excerpt verified in the source — verbatim, in the source's own language“Analysis of FeLV insertion sites in the MCF-7 mammary carcinoma cell line revealed strong bias towards active chromatin marks with no evidence of significant post-integration growth selection.”
This describes FeLV integration in a human cell line. Failure to detect significant growth selection does not establish its absence, and the finding does not establish integration preferences in cats.
EvidenceLevel D — Indirect evidence: other species or retrovirusConfidence 100/100
A meta-analysis of gamma-retrovirus integration profiling studies in human CD34+, K562 and HepG2 cells reported cancer gene bias and cell-type specificity, with a shared integration hotspot at MALAT1.
Excerpt verified in the source — verbatim, in the source's own language“A meta-analysis based on several gamma-retrovirus integration profiling (GRIP) studies in human cells (CD34+, K562, HepG2) revealed a similar cancer gene bias but also remarkable cell-type specificity, with prominent exceptions including a universal integration hotspot at the long non-coding RNA MALAT1.”
This is a finding across human-cell gamma-retrovirus studies. The excerpt does not establish that every included study used FeLV or that MALAT1 is a shared integration hotspot in feline cells.
Provenance
Source: Gamma-Retrovirus Integration Marks Cell Type-Specific Cancer Genes: A Novel Profiling Tool in Cancer Genomics.
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