microRNA-106b-5p and Rab10: Potential Markers of Acute Myeloid Leukemia.

This study focuses on acute myeloid leukemia (AML), a condition with a 5-year survival rate below 30% despite various treatment options. Recent strides in targeted therapies have shown promise, leading to better outcomes with minimal toxicity. These advances underscore the importance of discovering new diagnostic and prognostic targets for AML. In this context, the authors investigated the expression of microRNA-106b-5p (miR-106b-5p), Rab10 mRNA, and Rab10 proteins in peripheral blood and bone marrow (BM) samples from both healthy individuals and AML patients at different stages of the disease (initial diagnosis, recurrence, and complete remission). This examination aimed to identify potential biomarkers for AML diagnosis, treatment, and prognosis. From June 2021 to December 2022, they collected 100 BM and peripheral blood samples. The relative expression of miR-106b-5p and Rab10 mRNA in the BM of AML patients was measured using Real-time polymerase chain reaction (qRT-PCR), while the relative expression of Rab10 protein in serum was determined using the ELISA method. The chromosomal karyotype of initially diagnosed patients was analyzed using the R tape. The qRT-PCR results revealed that the expression of miR-106b-5p and Rab10 mRNA were significantly higher in patients at initial diagnosis and recurrence compared with healthy individuals and those in complete remission (p < 0.001). They observed a significant reduction in the expression of miR-106b-5p, Rab10 mRNA, and Rab10 protein in the BM and peripheral blood of patients during complete remission (p < 0.05), as demonstrated by dynamic monitoring of five patients in the initial group. Furthermore, they found a close association between the expression of miR-106b-5p and the number of white blood cells at the initial diagnosis in AML patients (p < 0.05). Spearman correlation analysis revealed a positive correlation among miR-106b-5p, Rab10 mRNA, and Rab10 proteins (p < 0.05). The diagnostic potential of miR-106b-5p and Rab10 proteins was underscored by Receiver Operating Characteristic (ROC) curve analysis, which demonstrated their high accuracy in AML diagnosis (AUC: 0.944 and 0.853, respectively; p < 0.0001). Additionally, Kaplan-Meier survival analysis suggested that lower expression of these markers was associated with better prognoses (p < 0.05). In summary, their findings propose miR-106b-5p and Rab10 proteins as promising biomarkers for AML, offering insights for diagnosis, treatment, and prognosis.

Acute myeloid leukemia with a novel AKAP9::PDGFRA fusion transformed from essential thrombocythemia: A case report and mini review.

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy associated with various combinations of gene mutations, epigenetic abnormalities, and chromosome rearrangement-related gene fusions. Despite the significant degree of heterogeneity in its pathogenesis, many gene fusions and point mutations are recurrent in AML and have been employed in risk stratification over the last several decades. Gene fusions have long been recognized for understanding tumorigenesis and their proven roles in clinical diagnosis and targeted therapies. Advances in DNA sequencing technologies and computational biology have contributed significantly to the detection of known fusion genes as well as for the discovery of novel ones. Several recurring gene fusions in AML have been linked to prognosis, treatment response, and disease progression. In this report, we present a case with a long history of essential thrombocythemia and hallmark CALR mutation transforming to AML characterized by a previously unreported AKAP9::PDGFRA fusion gene. We propose mechanisms by which this fusion may contribute to the pathogenesis of AML and its potential as a molecular target for tyrosine kinase inhibitors.

Efficacy of venetoclax and rituximab in the treatment of concurrent acute myeloid leukemia and untreated chronic lymphocytic leukemia: A case report and literature review.

To date, few cases of concurrent acute myeloid leukemia (AML) and untreated chronic lymphocytic leukemia (CLL) have been reported. Due to the complexity of the pathogenesis and the absence of a uniform treatment regimen, the associated prognosis remains poor. The present study reports the case of a 58-year-old male with asymptomatic leukocytosis, who was previously healthy with no malignancies. Flow cytometry analysis revealed protocytosis, monocytosis and monoclonal B lymphocytosis in a bone marrow specimen. Results of a gene rearrangement assay demonstrated positive immunoglobulin heavy-chain variable region gene status in monoclonal B lymphocytes. Thus, the patient was diagnosed with AML with maturation (AML-M2) that co-existed with untreated CLL. The normative daunorubicin (40 mg/m2 on days 1-3) and cytarabine (80 mg/m2 on days 1-7) regimen combined with venetoclax (400 mg on days 1-7) and rituximab (375 mg/m2 on day 0) was used as induction chemotherapy. The patient achieved morphological complete remission in both AML and CLL following the first course of chemotherapy. In addition, the present study retrospectively analyzed the data of 22 patients with concurrent AML and untreated CLL, and the results demonstrated that the median age at the time of AML diagnosis was 69 years (range, 52-86 years). Moreover, the male:female ratio was 6.33:1 and AML-M2 was the most frequent subtype at diagnosis. The presence of a complex karyotype was associated with the poorest prognosis, and patients who received venetoclax often exhibited an improved prognosis. In conclusion, the combination of venetoclax and rituximab improves the prognosis of patients with concurrent AML and untreated CLL.

NAD metabolism-related genes provide prognostic value and potential therapeutic insights for acute myeloid leukemia.

Introduction: Acute myeloid leukemia (AML) is an aggressive blood cancer with high heterogeneity and poor prognosis. Although the metabolic reprogramming of nicotinamide adenine dinucleotide (NAD) has been reported to play a pivotal role in the pathogenesis of acute myeloid leukemia (AML), the prognostic value of NAD metabolism and its correlation with the immune microenvironment in AML remains unclear. Methods: We utilized our large-scale RNA-seq data on 655 patients with AML and the NAD metabolism-related genes to establish a prognostic NAD metabolism score based on the sparse regression analysis. The signature was validated across three independent datasets including a total of 1,215 AML patients. ssGSEA and ESTIMATE algorithms were employed to dissect the tumor immune microenvironment. Ex vivo drug screening and in vitro experimental validation were performed to identify potential therapeutic approaches for the high-risk patients. In vitro knockdown and functional experiments were employed to investigate the role of SLC25A51, a mitochondrial NAD+ transporter gene implicated in the signature. Results: An 8-gene NAD metabolism signature (NADM8) was generated and demonstrated a robust prognostic value in more than 1,800 patients with AML. High NADM8 score could efficiently discriminate AML patients with adverse clinical characteristics and genetic lesions and serve as an independent factor predicting a poor prognosis. Immune microenvironment analysis revealed significant enrichment of distinct tumor-infiltrating immune cells and activation of immune checkpoints in patients with high NADM8 scores, acting as a potential biomarker for immune response evaluation in AML. Furthermore, ex vivo drug screening and in vitro experimental validation in a panel of 9 AML cell lines demonstrated that the patients with high NADM8 scores were more sensitive to the PI3K inhibitor, GDC-0914. Finally, functional experiments also substantiated the critical pathogenic role of the SLC25A51 in AML, which could be a promising therapeutic target. Conclusion: Our study demonstrated that NAD metabolism-related signature can facilitate risk stratification and prognosis prediction in AML and guide therapeutic decisions including both immunotherapy and targeted therapies.

Combining the novel FLT3 and MERTK dual inhibitor MRX-2843 with venetoclax results in promising antileukemic activity against FLT3-ITD AML.

FMS-like tyrosine kinase 3 (FLT3) mutations occur in approximately one third of acute myeloid leukemia (AML) patients. FLT3-Internal tandem duplication (FLT3-ITD) mutations are the most common FLT3 mutations and are associated with a poor prognosis. Gilteritinib is a FLT3 inhibitor that is US FDA approved for treating adult patients with relapsed/refractory AML and a FLT3 mutation. While gilteritinib monotherapy has improved patient outcome, few patients achieve durable responses. Combining gilteritinib with venetoclax (VEN) appears to make further improvements, though early results suggest that patients with prior exposure to VEN fair much worse than those without prior exposure. MRX-2843 is a promising inhibitor of FLT3 and MERTK. We recently demonstrated that MRX-2843 is equally potent as gilteritinib in FLT3-ITD AML cell lines in vitro and primary patient samples ex vivo. In this study, we investigated the combination of VEN and MRX-2843 against FLT3-ITD AML cells. We found that VEN synergistically enhances cell death induced by MRX-2843 in FLT3-mutated AML cell lines and primary patient samples. Importantly, we found that VEN synergistically enhances cell death induced by MRX-2843 in FLT3-ITD AML cells with acquired resistance to cytarabine (AraC) or VEN+AraC. VEN and MRX-2843 significantly reduce colony-forming capacity of FLT3-ITD primary AML cells. Mechanistic studies show that MRX-2843 decreases Mcl-1 and c-Myc protein levels via transcriptional regulation and combined MRX-2843 and VEN significantly decreases oxidative phosphorylation in FLT3-ITD AML cells. Our findings highlight a promising combination therapy against FLT3-ITD AML, supporting further in vitro and in vivo testing.

Myeloid­derived suppressor cells as targets of emerging therapies and nanotherapies (Review).

Breast cancer (BC) is the leading cause of cancer-related mortality among women worldwide. Immunotherapies are a promising approach in cancer treatment, particularly for aggressive forms of BC with high mortality rates. However, the current eligibility for immunotherapy remains limited to a limited fraction of patients with BC. Myeloid-derived suppressor cells (MDSCs), originating from myeloid cells, are known for their dual role in immunosuppression and tumor promotion, significantly affecting patient outcomes by fostering the formation of premetastatic niches. Consequently, targeting MDSCs has emerged as a promising avenue for further exploration in therapeutic interventions. Leveraging nanotechnology-based drug delivery systems, which excel in accumulating drugs within tumors via passive or active targeting mechanisms, are a promising strategy for the use of MDSCs in the treatment of BC. The present review discusses the immunosuppressive functions of MDSCs, their role in BC, and the diverse strategies for targeting them in cancer therapy. Additionally, the present review discusses future advancements in BC treatments focusing on MDSCs. Furthermore, it elucidates the mechanisms underlying MDSC activation, recruitment and differentiation in BC progression, highlighting the clinical characteristics that render MDSCs suitable candidates for the therapy and targeted nanotherapy of BC.

Acute Leukemia and Latent Tuberculosis Infection in Italy: Quantiferon-Tb Test Screening in a Low Tuberculosis Incidence Country.

Background: Identification of latent tuberculosis infection (LTBI) is a critical step of tuberculosis surveillance, especially in low-incidence countries. However, it is limited to situations with a higher probability of developing active disease, e.g., patients with hematological malignancies. According to guidelines, in TB non-endemic countries, no clear screening program is established at diagnosis for patients with acute leukemia (AL). The primary endpoint of this study was to establish the prevalence of LTBI in patients with a diagnosis of AL using QuantiFERON (QFT)-TB. Secondarily, radiological and clinical features driving the increased risk of LTBI were evaluated. Methods: QFT-TB screening was performed before induction or consolidation in all patients with AL (myeloid and lymphoid) treated at our Institution between October 2019 and August 2023. Results: We accrued 62 patients, of whom 7 (11,3%) tested positive, without any symptoms or signs of active TB, and 2 (3,2%) resulted as indeterminate. All positive patients started prophylaxis with isoniazid 300 mg daily, while patients whose test was indeterminate did not receive any prophylaxis. Active TB was excluded by imaging, as well as microscopic, cultural, and molecular examination on bronchoalveolar lavage if signs of any infection were detected. During the 46 months of observation, no patients developed TB reactivation. Conclusions: Despite the low sample size, 1/10 of our patients had prior TB exposure, hinting that LTBI could be more common than expected in Italy. This finding suggests implementing TB screening in the pre-treatment setting, particularly at a time when more active treatments are becoming available also for patients ineligible for intensive chemotherapy.

BTK acts as a modulator of the response to imatinib in chronic myeloid leukemia.

The use of tyrosine kinase inhibitors, such as imatinib, against the chronic myeloid leukemia (CML)-causing kinase BCR::ABL1 has become the model for successful targeted therapy. Nevertheless, drug resistance remains a clinical problem. Analysis of genome-wide expression and genetic aberrations of an in vitro imatinib-resistant CML cell line revealed downregulation of Bruton's tyrosine kinase (BTK), predominantly associated with B cell malignancies, and a novel BTK kinase domain variant in imatinib resistance. This raised the question of the role of BTK in imatinib-resistant CML. In the present study, BTK downregulation and the presence of the BTK variant c.1699_1700delinsAG p.(Glu567Arg) were confirmed in imatinib resistance in vitro. Similarly, BTK inhibition or small interfering RNA-mediated BTK knockdown reduced imatinib susceptibility by 84 and 71%, respectively. BTK overexpression was detrimental to CML cells, as proliferation was significantly reduced by 20.5% under imatinib treatment. In addition, BTK rescue in imatinib-resistant cells restored imatinib sensitivity. The presence of the BTK p.(Glu567Arg) variant increased cell numbers (57%) and proliferation (37%) under imatinib exposure. These data demonstrate that BTK is important for the development of imatinib resistance in CML: Its presence increased drug response, while its absence promotes imatinib resistance. Moreover, the BTK p.(Glu567Arg) variant abrogates imatinib sensitivity. These findings demonstrate a context-dependent role for BTK as an oncogene in B cell malignancies, but as a tumor suppressor in other neoplasms.

Interleukin-2 mediated associations between gut microbiota and acute myeloid leukemia: A population-based mediation Mendelian randomization study.

The relationship between the gut microbiota and acute myeloid leukemia (AML) has been established, but the exact role of interleukin (IL) in mediating this relationship has remained unclear. This study aimed to utilize whether interleukins mediate the relationships between gut microbiota and AML, thereby identifying potential novel targets for future AML treatment. Mendelian randomization (MR) is a method for finding the causality of exposure and outcome. Final instrumental variables were selected based on MR assumptions, and used to judge validity of the results. Our study identified risk and protective factors for AML, and interleukin-related gut microbiota. Finally, mediation MR analyses resulted in Interleukin-2 (IL-2) mediated associations between Clostridiaceae 1, Clostridium sensu stricto 1 and AML, with IL-2 respectively explaining 13.96 % and 12.11 % of the total effect of the aforementioned gut microbiota on AML. Our results successfully identified causal effects between specific gut microbiota, AML, and interleukins, while also elucidating the mediating role of IL-2 in these associations using MR analysis. These findings provide valuable insights into potential therapeutic targets for AML treatment.

Practical considerations in the management of patients treated with bosutinib for chronic myeloid leukemia.

Bosutinib is a second-generation tyrosine kinase inhibitor indicated for the treatment of patients with newly diagnosed Philadelphia chromosome-positive chronic phase chronic myeloid leukemia (CML), and for patients with Ph + chronic phase, accelerated phase, or blast phase CML resistant or intolerant to prior therapy. As is the case for all TKIs approved for treatment of CML, bosutinib is associated with adverse events (AEs) that require appropriate management to ensure adherence to treatment and optimized outcomes. The aim of this review is to provide physicians with updated practical information for the prevention and management of AEs occurring during treatment with bosutinib, including dosing strategies, based on the latest published evidence and clinical experience. Clinical studies and real-world evidence have shown bosutinib has a generally favorable safety profile, which has remained consistent across lines of therapy and in long-term reports. Adjusting the starting dose and/or modifying the dose during treatment with bosutinib are important strategies to manage AEs and improve tolerability, which are recognized within the label and in treatment guidelines. Dosing adjustment strategies to manage AEs are a recognized management approach for other TKIs in the treatment of CML and are not exclusive to bosutinib. In summary, long-term results from clinical trials and emerging real-world evidence demonstrate bosutinib has a safety profile that can largely be managed with treatment modifications and/or supportive care. Increased experience in managing toxicities and by using a personalized dosing approach may further improve adherence and outcomes with bosutinib.

Suppression of MyD88 disturbs gut microbiota and activates the NLR pathway and hence fails to ameliorate DSS-induced colitis.

Background: Myeloid differentiation factor 88 (MyD88) is the core adaptor for Toll-like receptors defending against microbial invasion and initiating a downstream immune response during microbiota-host interaction. However, the role of MyD88 in the pathogenesis of inflammatory bowel disease is controversial. This study aims to investigate the impact of MyD88 on intestinal inflammation and the underlying mechanism. Methods: MyD88 knockout (MyD88-/-) mice and the MyD88 inhibitor (TJ-M2010-5) were used to investigate the impact of MyD88 on acute dextran sodium sulfate (DSS)-induced colitis. Disease activity index, colon length, histological score, and inflammatory cytokines were examined to evaluate the severity of colitis. RNA transcriptome analysis and 16S rDNA sequencing were used to detect the potential mechanism. Results: In an acute DSS-colitis model, the severity of colitis was not alleviated in MyD88-/- mice and TJ-M2010-5-treated mice, despite significantly lower levels of NF-κB activation being exhibited compared to control mice. Meanwhile, 16S rDNA sequencing and RNA transcriptome analysis revealed a higher abundance of intestinal Proteobacteria and an up-regulation of the nucleotide oligomerization domain-like receptors (NLRs) signaling pathway in colitis mice following MyD88 suppression. Further blockade of the NLRs signaling pathway or elimination of gut microbiota with broad-spectrum antibiotics in DSS-induced colitis mice treated with TJ-M2010-5 ameliorated the disease severity, which was not improved solely by MyD88 inhibition. After treatment with broad-spectrum antibiotics, downregulation of the NLR signaling pathway was observed. Conclusion: Our study suggests that the suppression of MyD88 might be associated with unfavorable changes in the composition of gut microbiota, leading to NLR-mediated immune activation and intestinal inflammation.

GNL3L exhibits pro-tumor activities via NF-κB pathway as a poor prognostic factor in acute myeloid leukemia.

Acute myeloid leukemia (AML) is the leukemia with the worst prognosis, and current knowledge of AML pathogenesis and available therapies for AML remain limited. 40% of AML patients exhibit elevated nuclear factor kappa B (NF-κB) activity, which provides a compelling rationale for targeting the NF-κB pathway in AML. Guanine nucleotide-binding protein-like 3-like protein (GNL3L) is a recently identified pro-oncogene that promotes NF-κB activation in a variety of malignancies. For the first time, we comprehensively examined GNL3L expression in AML, reporting GNL3L as a poor prognostic factor in three independent AML cohorts. GNL3L enhanced RELA activity, activated NF-κB, promoted AML cell proliferation, resisted apoptosis, and encouraged cytarabine resistance in AML. In conclusion, these data suggest a role for GNL3L in the malignant process of AML and as a promising therapeutic target.

Successful Therapeutic Leukapheresis for Chronic Myeloid Leukemia Identified by Persistent Erection: A Case Report.

Cytoreduction in leukostasis can be achieved using leukapheresis. We report a case of chronic myeloid leukemia (CML) identified by a persistent erection, which was successfully treated using the Spectra Optia®ï¸Ž apheresis system. A 29-year-old male presented with an erection for 12 hours without identified triggers and no improvement despite penile corpus cavernosum puncture. His white blood cell count was 458,930/µL. A diagnosis of CML-induced persistent erection with secondary hyperleukocytosis was established. Following an emergency bilateral penile corpus cavernosum incision (distal shunting), he received hydroxyurea and febuxostat. Persistent erection resolved after leukapheresis for two consecutive days. Rapid leukocyte count reduction can effectively address leukostasis in CML without major complications.

Exploiting the potential of the ubiquitin-proteasome system in overcoming tyrosine kinase inhibitor resistance in chronic myeloid leukemia.

The advent of tyrosine kinase inhibitors (TKI) targeting BCR-ABL has drastically changed the treatment approach of chronic myeloid leukemia (CML), greatly prolonged the life of CML patients, and improved their prognosis. However, TKI resistance is still a major problem with CML patients, reducing the efficacy of treatment and their quality of life. TKI resistance is mainly divided into BCR-ABL-dependent and BCR-ABL-independent resistance. Now, the main clinical strategy addressing TKI resistance is to switch to newly developed TKIs. However, data have shown that these new drugs may cause serious adverse reactions and intolerance and cannot address all resistance mutations. Therefore, finding new therapeutic targets to overcome TKI resistance is crucial and the ubiquitin-proteasome system (UPS) has emerged as a focus. The UPS mediates the degradation of most proteins in organisms and controls a wide range of physiological processes. In recent years, the study of UPS in hematological malignant tumors has resulted in effective treatments, such as bortezomib in the treatment of multiple myeloma and mantle cell lymphoma. In CML, the components of UPS cooperate or antagonize the efficacy of TKI by directly or indirectly affecting the ubiquitination of BCR-ABL, interfering with CML-related signaling pathways, and negatively or positively affecting leukemia stem cells. Some of these molecules may help overcome TKI resistance and treat CML. In this review, the mechanism of TKI resistance is briefly described, the components of UPS are introduced, existing studies on UPS participating in TKI resistance are listed, and UPS as the therapeutic target and strategies are discussed.

[Efficacy and safety of gilteritinib-based combination therapy bridging allo-HSCT in relapsed or refractory acute myeloid leukemia patients with positive FLT3-ITD mutation].

Objective: This study aims to evaluate the safety and effectiveness of gilteritinib (Gilt) -based combination therapy bridging allo-HSCT for FLT3-ITD(+) R/R AML. Additionally, it aims to assess the impact of Gilt maintenance therapy on the prognosis of patients after allo-HSCT. Methods: The clinical data of 26 patients with FLT3-ITD(+) R/R AML treated at the First Affiliated Hospital of Soochow University from August 2019 to January 2023 were retrospectively analyzed. The analysis included an assessment of the composite complete remission rate (CRc), overall survival (OS) time, disease-free survival (DFS) time, and adverse events experienced by all enrolled patients. Results: A total of 26 patients with FLT3-ITD(+) R/R AML were enrolled, including 14 men and 12 women with a median age of 38 (18-65) years. A total of 18 cases were refractory, and eight cases were relapsed. The curative effect evaluation conducted between 14 and 21 days showed that the complete remission (CR) rate was 26.9% (7/26), the CR with hematology incomplete recovery was 57.7% (15/26), and the partial response (PR) rate was 7.7% (2/26). The CRc was 84.6% (22/26), and the minimal residual disease (MRD) negativity rate was 65.4%. The 12 month cumulative OS rate for all patients was 79.0%, and the 24 month cumulative OS rate was 72.0%. The median OS time was not determined. The median follow-up time was 16.0 months. Among the patients who responded to treatment, the 12 month cumulative DFS rate was 78.0%, and the 24 month cumulative DFS rate was 71.0%. The median DFS time was not determined. Patients who received allo-HSCT had a median OS time that was significantly longer than those who did not receive allo-HSCT (3.3 months, 95%CI 2.2-4.3 months, P=0.005). The median OS time of patients with or without Gilt maintenance therapy after allo-HSCT was not determined, but the OS time of patients with Gilt maintenance therapy after allo-HSCT treatment was longer than that of patients without Gilt maintenance therapy after allo-HSCT treatment (P=0.019). The FLT3-ITD mutation clearance rate in this study was 38.5%, and the median OS time of patients with FLT3-ITD mutation clearance was not determined but was significantly longer than the median OS of patients without FLT3-ITD mutation clearance (15.0 months; P=0.018). The most common grade 3 and above hematological adverse events of Gilt-based combination therapy included leukopenia (76.9%), neutropenia (76.9%), febrile neutropenia (61.5%), thrombocytopenia (69.2%), and anemia (57.7%). One patient developed differentiation syndrome during oral Gilt maintenance therapy after allo-HSCT treatment, but his condition improved after treatment. Conclusion: The Gilt-based combination therapy is highly effective in treating FLT3-ITD(+) R/R AML. It demonstrates a high CRc, MRD negativity rate, and rapid onset, leading to a significant improvement in patients' survival. Furthermore, the clearance rate of FLT3-ITD mutation is notably high. Additionally, implementing bridging allo-HSCT and Gilt maintenance therapy after allo-HSCT treatment has considerably enhances patients' survival. Closely monitoring and managing any adverse event that may occur during treatment are crucial.

Lysosomal cation channel TRPML1 suppression sensitizes acute myeloid leukemia cells to chemotherapeutics by inhibiting autophagy.

Despite the implementation of novel therapeutic regimens and extensive research efforts, chemoresistance remains a formidable challenge in the treatment of acute myeloid leukemia (AML). Notably, the involvement of lysosomes in chemoresistance has sparked interest in developing lysosome-targeted therapies to sensitize tumor cells to currently approved chemotherapy or as innovative pharmacological approaches. Moreover, as ion channels on the lysosomal membrane are critical regulators of lysosomal function, they present potential as novel targets for enhancing chemosensitivity. Here, we discovered that the expression of a lysosomal cation channel, namely transient receptor potential mucolipin 1 (TRPML1), was elevated in AML cells. Inhibiting TRPML1 individually does not impact the proliferation and apoptosis of AML cells. Importantly, inhibition of TRPML1 demonstrated the potential to modulate the sensitivity of AML cells to chemotherapeutic agents. Exploration of the underlying mechanisms revealed that suppression of TRPML1 impaired autophagy while concurrently increasing the production of reactive oxygen species (ROS) and ROS-mediated lipid peroxidation (Lipid-ROS) in AML cells. Finally, the knockdown of TRPML1 significantly reduced OCI-AML3 tumor growth following chemotherapy in a mouse model of human leukemia. In summary, targeting TRPML1 represents a promising approach for combination therapy aimed at enhancing chemosensitivity in treating AML.

PRPS2-mediated modulation of the antitumor immune response in lung cancer through CCL2-mediated tumor-associated macrophages and myeloid-derived suppressor cells.

BACKGROUND: Phosphoribosyl pyrophosphate synthetase 2 (PRPS2) is known as an oncogene in many types of cancers, including lung cancer. However, its role in regulating tumor-associated macrophages (TAM) and myeloid-derived suppressor cells (MDSC) remains unclear. Our study aimed to explore the involvement of PRPS2 in TAM and MDSC regulation. METHODS: Stable Lewis lung cancer (LLC) cell lines were established using a lentivirus system. These LLC lines were then used to establish tumor model in mice. The levels of target genes were determined using qPCR, western blotting, and ELISA assays. The percentage of different immune cell types was analyzed using fluorescence-activated cell sorting. The chemotaxis ability of TAM and MDSC was evaluated using an in vitro transwell chemotaxis assay. RESULTS: Notably, PRPS2 was found to regulate the chemotaxis of TAM and MDSC in tumor cells, as evidenced by the positive correlation of PRPS2 expression levels and abundance of TAM and MDSC populations. In addition, the expression of CCL2, mediated by PRPS2, was identified as a key factor in the chemotaxis of TAM and MDSC, as evidenced by a significant reduction in macrophages and MDSC numbers in the presence of the CCL2 antibody. Furthermore, in vivo experiments confirmed the involvement of PRPS2 in mediating CCL2 expression. PRPS2 was also found to regulate immune cell infiltration into tumors, whereas knockdown of CCL2 reversed the phenotype induced by PRPS2 overexpression. In tumor tissues from mice implanted with LLC-PRPS2-shCCL2 cells, a notable increase in CD4+ and CD8+ T cell percentages, alongside a marked decrease in TAMs, M-MDSC, and PMN-MDSC, was observed. CONCLUSION: Taken together, PRPS2 plays a crucial role in modulating the antitumor immune response by reprogramming CCL2-mediated TAM and MDSC.