Role of the STING pathway in myeloid neoplasms: a prospero-registered systematic review of principal hurdles of STING on the road to the clinical practice.

Myeloid neoplasms are a group of bone marrow diseases distinguished by disruptions in the molecular pathways that regulate the balance between hematopoietic stem cell (HSC) self-renewal and the generation of specialized cells. Cytokines and chemokines, two important components of the inflammatory process, also influence hematological differentiation. In this scenario, immunological dysregulation plays a pivotal role in the pathogenesis of bone marrow neoplasms. The STING pathway recognizes DNA fragments in the cell cytoplasm and triggers an immune response by type I interferons. The role of STING in cancer has not yet been established; however, both actions, as an oncogene or tumor suppressor, have been documented in other types of cancer. Therefore, we performed a systematic review (registered in PROSPERO database #CRD42023407512) to discuss the role of STING pathway in the advancement of pathogenesis and/or prognosis for different myeloid neoplasms. In brief, scientific evidence supports investigations that primarily use cell lines from myeloid neoplasms, such as leukemia. More high-quality research and clinical trials are needed to understand the role of the STING pathway in the pathology of hematological malignancies. Finally, the STING pathway suggests being a promising therapeutic molecular target, particularly when combined with current drug therapies.

Gene expression patterns of Sirtuin family members (SIRT1 TO SIRT7): Insights into pathogenesis and prognostic of Myelodysplastic neoplasm.

To assess and validate the gene expression profile of SIRTs (SIRT1, SIRT2, SIRT3, SIRT4, SIRT5, SIRT6, and SIRT7) in relation to the pathogenesis and prognostic progression of Myelodysplastic neoplasm (MDS). Eighty bone marrow samples of patients with de novo MDS were diagnosed according to WHO 2022 and IPSS-R criteria. Ten bone marrow samples were obtained from elderly healthy volunteers and used as control samples. Gene expression levels of all SIRTs were assessed using RT-qPCR assays. Downregulation of SIRT2 (p = 0.009), SIRT3 (p = 0.048), SIRT4 (p = 0.049), SIRT5 (p = 0.046), SIRT6 (p = 0.043), and SIRT7 (p = 0.047) was identified in MDS patients compared to control individuals. Also, we identified that while SIRT2-7 genes are typically down-regulated in MDS patients compared to normal controls, there are relative expression variations among MDS patient subgroups. Specifically, SIRT4 (p = 0.029) showed increased expression in patients aged 60 or above, and both SIRT2 (p = 0.016) and SIRT3 (p = 0.036) were upregulated in patients with hemoglobin levels below 8 g/dL. SIRT2 (p = 0.045) and SIRT3 (p = 0.033) were highly expressed in patients with chromosomal abnormalities. Different SIRTs exhibited altered expression patterns concerning specific MDS clinical and prognostic characteristics. The downregulation in SIRTs genes (e.g., SIRT2 to SIRT7) expression in Brazilian MDS patients highlights their role in the disease's development. The upregulation of SIRT2 and SIRT3 in severe anemia patients suggests a potential link to manage iron overload-related complications in transfusion-dependent patients. Moreover, the association of SIRT2/SIRT3 with genomic instability and their role in MDS progression signify promising areas for future research and therapeutic targets. These findings underscore the importance of SIRT family in understanding and addressing MDS, offering novel clinical, prognostic, and therapeutic insights for patients with this condition.

High PD-L1 expression is associated with unfavorable clinical features in myelodysplastic neoplasms.

INTRODUCTION: Immune checkpoints are regulators of the immune system response that allow self-tolerance. Molecules such as Programmed Cell Death Protein 1 (PD-1) and its Ligand (PD-L1) participate in the immune checkpoint by signaling co-inhibition of lymphocyte responses. In cancers, PD-L1 expression is associated with the immune evasion mechanism, which favors tumor growth. The use of anti-PD-1/PD-L1 drugs is already well described in solid tumors, but still not fully understood in hematologic malignancies. Myelodysplastic neoplasms (MDSs) are heterogeneous bone marrow disorders with an increased risk of progression to Acute Myeloid Leukemia (AML). The MDS affects hematopoietic stem cells and its pathogenesis is linked to genetic and epigenetic defects, in addition to immune dysregulation. The influence of the PD-L1 on the MDS remains unknown. METHODS: In this study, we evaluated the mRNA expression of the PD-L1 in 53 patients with MDS, classified according to the WHO 2016 Classification. RESULTS: Patients with dyserythropoiesis presented significantly higher PD-L1 expression than patients without dyserythropoiesis (p = 0.050). Patients classified as having MDS with an excess of blasts 2 (MDS-EB2) presented a significant upregulation in the mRNA expression of the PD-L1 compared to the MDS with an excess of blasts 1 (MDS-EB1) (p = 0.050). Furthermore, we detected three patients with very high levels of PD-L1 expression, being statistically classified as outliers. CONCLUSION: We suggested that the high expression of the PD-L1 is associated with a worse prognosis in the MDS and functional studies are necessary to evaluate the possible use of anti-PD-L1 therapies for high-risk MDS, such as the MDS-EBs.

ERVs-TLR3-IRF axis is linked to myelodysplastic syndrome pathogenesis.

Toll-like receptors are mutated or overexpressed in up to 50% of patients with myelodysplastic syndrome (MDS). Endogenous retroviruses (ERV) trigger TLR3 leading to interferon regulatory genes (IRFs) activation. We evaluated if the ERVs-TLR3-IRF axis activation would be linked to MDS pathogenesis and we also conducted a detailed cancer analysis of the ERVs, TLR3 and IRFs gene expression in 30 cancer types using GEPIA database. Seventy-nine bone marrow samples from patients with MDS were evaluated for cytogenetics and quantitative real­time PCR of TLR3, ERVK6, ERVW-1, ERV3-1, IRF3 and IRF7. Patients with dyserythropoiesis showed higher TLR3 (p = 0.035), ERVK6 (p = 0.001), ERVW1 (p = 0.045) and ERV3-1 (p = 0.016) expression than patients without dyserythropoiesis. Upregulation of Interferon Regulatory Factors, IRF3 and IRF7, was associated with poor prognostic markers in MDS such as > 10% of blasts (p = 0.003-IRF3; p = 0.009-IRF7), low platelets count (< 50.000/mm3) (p = 0.001-IRF3; p = 0.021-IRF7), transfusion dependence (p = 0.014-IRF3) and chromosomal abnormalities (p = 0.036-IRF7). We found strong correlations between ERVK6-ERVW1 (r = 0.800; r2 = 0.640; p = 0.000), ERVW1-ERV3-1 (r = 0.715; r2 = 0.511; p = 0.000), and IRF7-IRF3 (r = 0.567; r2 = 0.321; p = 0.000) and moderate correlation between ERVK6-ERV3-1(r = 0.485; r2 = 0.235; p = 0.000), ERVW1-IRF7 (r = 0.389; r2 = 0.151; p = 0.001), ERVW1-IRF3 (r = 0.357; r2 = 0.127; p = 0.004), ERV3-1-IRF7 (r = 0.314; r2 = 0.098; p = 0.009), and ERV3-1-IRF3 (r = 0.324; r2 = 0.104; p = 0.007). Using GEPIA Database in 30 cancer types, we detected a typical pattern of upregulation as here presented in MDS. We suggest TLR3 activation by ERVs is linked to MDS pathogenesis leading to bone marrow failure. Abnormal double-stranded RNA (dsRNA) expression of Endogenous Retroviruses (ERV) triggers TLR3 hyperactivation. This induces IRF3, IRF7, and NF-kB to translocate to the nucleus and activate transcription of IFNα/ß which binds to the type I-IFN receptor promoting interferon response. Thus, just as TLR4 induces a crucial myeloid shift, the ERVs-TLR3 axis may play an important role in establishing one of the most striking characteristics in MDS, dyserythropoiesis.