Project description:Here we systematically dissected PDA intrinsic mechanisms of immune evasion by in vitro and in vivo CRISPR screening. Beyond the conserved set of genes regulating anti-cancer immunity we identified Rnf31 and Vps4b as essential factors required for escaping CD8+ T cell-killing. While the absence of Rnf31 induced sensitivity to T cell killing through TNF-mediated apoptosis in murine cancer cells and human PDA organoids, loss of Vps4b abrogated functional autophagy, resulting in accumulation of CD8+ T cell-derived granzyme B and subsequent tumor cell lysis.
Project description:Aging is associated with significant changes in the hematopoietic system, including increased inflammation, impaired hematopoietic stem cell (HSC) function, and increased incidence of myeloid malignancy. Inflammation of aging (“inflammaging”) has been proposed as a driver of age-related changes in HSC function and myeloid malignancy, but mechanisms linking these phenomena remain poorly defined. Here, we identify loss of miR-146a as driving aging-associated inflammation in AML patients. miR-146a expression declined in old wild-type mice, and loss of miR-146a promoted premature HSC aging and inflammation in young miR-146a-null mice, preceding development of aging-associated myeloid malignancy. Using single-cell assays of HSC quiescence, stemness, differentiation potential, and epigenetic state to probe HSC function and population structure, we found that loss of miR-146a depleted a subpopulation of primitive, quiescent HSCs. DNA methylation and transcriptome profiling implicated NF-κB, IL6, and TNF as potential drivers of HSC dysfunction, activating an inflammatory signaling relay promoting IL6 and TNF secretion from mature miR-146a-/- myeloid and lymphoid cells. Reducing inflammation by targeting Il6 or Tnf was sufficient to restore single-cell measures of miR-146a-/- HSC function and subpopulation structure, and reduced the incidence of hematological malignancy in miR 146a-/- mice. miR-146a-/- HSCs exhibited enhanced sensitivity to IL6 stimulation, indicating that loss of miR-146a affects HSC function via both cell-extrinsic inflammatory signals and increased cell-intrinsic sensitivity to inflammation. Thus, loss of miR 146a regulates cell-extrinsic and -intrinsic mechanisms linking HSC inflammaging to the development of myeloid malignancy.
Project description:Aging is associated with significant changes in the hematopoietic system, including increased inflammation, impaired hematopoietic stem cell (HSC) function, and increased incidence of myeloid malignancy. Inflammation of aging (“inflammaging”) has been proposed as a driver of age-related changes in HSC function and myeloid malignancy, but mechanisms linking these phenomena remain poorly defined. Here, we identify loss of miR-146a as driving aging-associated inflammation in AML patients. miR-146a expression declined in old wild-type mice, and loss of miR-146a promoted premature HSC aging and inflammation in young miR-146a-null mice, preceding development of aging-associated myeloid malignancy. Using single-cell assays of HSC quiescence, stemness, differentiation potential, and epigenetic state to probe HSC function and population structure, we found that loss of miR-146a depleted a subpopulation of primitive, quiescent HSCs. DNA methylation and transcriptome profiling implicated NF-κB, IL6, and TNF as potential drivers of HSC dysfunction, activating an inflammatory signaling relay promoting IL6 and TNF secretion from mature miR-146a-/- myeloid and lymphoid cells. Reducing inflammation by targeting Il6 or Tnf was sufficient to restore single-cell measures of miR-146a-/- HSC function and subpopulation structure, and reduced the incidence of hematological malignancy in miR 146a-/- mice. miR-146a-/- HSCs exhibited enhanced sensitivity to IL6 stimulation, indicating that loss of miR-146a affects HSC function via both cell-extrinsic inflammatory signals and increased cell-intrinsic sensitivity to inflammation. Thus, loss of miR 146a regulates cell-extrinsic and -intrinsic mechanisms linking HSC inflammaging to the development of myeloid malignancy.
Project description:Epigenetic therapies that alter DNA- and/or histone modifications facilitate transcription of immunogenic repetitive elements that cull cancer cells through ‘viral mimicry’ responses. Paradoxically, cancer-initiating events that include functional inactivation of canonical tumor suppressor proteins also facilitate transcription of repetitive elements. Contributions of repetitive element transcription towards cancer initiation, and the mechanisms by which cancer cells evade lethal viral mimicry responses during tumor initiation remain poorly understood. In this report, we characterize patient-derived premalignant lesions of the fallopian tube along with syngeneic mouse models of epithelial ovarian cancer to explore the earliest events of tumorigenesis following loss of the p53 tumor suppressor protein. We report that p53 loss disrupts constitutive heterochromatin to permit transcription of immunogenic repetitive elements capable of activating viral mimicry responses. While acute viral mimicry activation diminishes cell fitness, chronic viral mimicry activation following p53 loss promotes epigenetic reprogramming that increases tolerance of cytosolic nucleic acids and diminishes cellular immunogenicity as a pro-survival adaptation. This selection process we describe as ‘viral mimicry conditioning’ can be partially attenuated by the reverse transcriptase inhibitor 3TC to delay spontaneous tumorigenesis. Altogether, these results reveal that viral mimicry conditioning following p53 loss selects for diminished cell immunogenicity to promote immune evasion upon cancer initiation. Disruption of viral mimicry conditioning during cancer initiation may represent a pharmacological target for early cancer interception.