AATF/Che-1 localizes to paraspeckles and suppresses R-loops accumulation and interferon activation in Multiple Myeloma.

Several kinds of stress promote the formation of three-stranded RNA:DNA hybrids called R-loops. Insufficient clearance of these structures promotes genomic instability and DNA damage, which ultimately contribute to the establishment of cancer phenotypes. Paraspeckle assemblies participate in R-loop resolution and preserve genome stability, however, the main determinants of this mechanism are still unknown. This study finds that in Multiple Myeloma (MM), AATF/Che-1 (Che-1), an RNA-binding protein fundamental to transcription regulation, interacts with paraspeckles via the lncRNA NEAT1_2 (NEAT1) and directly localizes on R-loops. We systematically show that depletion of Che-1 produces a marked accumulation of RNA:DNA hybrids. We provide evidence that such failure to resolve R-loops causes sustained activation of a systemic inflammatory response characterized by an interferon (IFN) gene expression signature. Furthermore, elevated levels of R-loops and of mRNA for paraspeckle genes in patient cells are linearly correlated with Multiple Myeloma progression. Moreover, increased interferon gene expression signature in patients is associated with markedly poor prognosis. Taken together, our study indicates that Che-1/NEAT1 cooperation prevents excessive inflammatory signaling in Multiple Myeloma by facilitating the clearance of R-loops. Further studies on different cancer types are needed to test if this mechanism is ubiquitously conserved and fundamental for cell homeostasis.

KEAP1-Mutant NSCLC: The Catastrophic Failure of a Cell-Protecting Hub.

Mutations in the KEAP1-NRF2 pathway are common in NSCLC, albeit with a prevalence of KEAP1 mutations in lung adenocarcinoma and an equal representation of KEAP1 and NFE2L2 (the gene encoding for NRF2) alterations in lung squamous cell carcinoma. The KEAP1-NRF2 axis is a crucial modulator of cellular homeostasis, enabling cells to tolerate oxidative and metabolic stresses, and xenobiotics. The complex cytoprotective response orchestrated by NRF2-mediated gene transcription embraces detoxification mechanisms, ferroptosis protection, and metabolic reprogramming. Given that the KEAP1-NRF2 pathway controls core cellular functions, it is not surprising that a number of clinical studies connected KEAP1 mutations to increased resistance to chemotherapy, radiotherapy, and targeted agents. More recently, an immune-cold tumor microenvironment was described as a typical feature of KEAP1-mutant lung adenocarcinoma. Consistently, a reduced efficacy of immunotherapy was reported in the KEAP1-mutant background. Nevertheless, the connection between KEAP1 and immune resistance seems more complex and dependent on coexisting genomic alterations. Given the clinical implications of deregulated KEAP1-NRF2 pathway in lung cancer, the development of pathway-directed anticancer treatments should be considered a priority in the domain of thoracic oncology.