High-level CD34 expression on megakaryocytes independently predicts an adverse outcome in patients with myelodysplastic syndromes

Clinical and Molecular Characteristics of Megakaryocytes in Myelodysplastic Syndrome

Objective  Myelodysplastic syndrome (MDS) is a malignant clonal disorder of hematopoietic stem cells which is characterized by morphologic dysplasia. However, the pathological characteristics of megakaryocytes (MKs) in MDS patients with gene mutation are not well established. Methods  Bone marrow MK specimens from 104 patients with primary MDS were evaluated, and all patients were distributed into two groups according to gene mutation associated with functional MKs. The morphologic and cellular characteristics of MKs and platelets were recorded and compared. Results  The more frequently mutated genes in MDS patients were TUBB1 (11.54%), VWF (8.65%), NBEAL2 (5.77%), and the most common point mutation was TUBB1 p.(R307H) and p.(Q43P). Patients with MK mutation showed a decrease in adenosine diphosphate-induced platelet aggregation, high proportion of CD34 + CD61 + MKs (10.00 vs. 4.00%, p  = 0.012), and short overall survival (33.15 vs. 40.50 months, p  = 0.013). Further, patients with a higher percent of CD34 + CD61 + MKs (≧20.00%) had lower platelet counts (36.00 × 10 9 /L vs. 88.50 × 10 9 /L, p  = 0.015) and more profound emperipolesis ( p  = 0.001). By analyzing RNA-sequencing of MKs, differentially expressed mRNA was involved in physiological processes including platelet function and platelet activation, especially for MDS patients with high percent of CD34 + CD61 + MKs. The high levels of expression of CD62P, CXCL10, and S100A9 mRNA, shown by RNA sequencing, were validated by PCR assay. Conclusion  High proportion of CD34 + CD61 + MKs was a poor prognostic factor in MDS patients with MK mutation. CD62P, CXCL10, and S100A9 may be the potential targets to evaluate the molecular link between gene defects and platelet function.

Metabolic sensor O-GlcNAcylation regulates megakaryopoiesis and thrombopoiesis through c-Myc stabilization and integrin perturbation

Metabolic state of hematopoietic stem cells (HSCs) is an important regulator of self‐renewal and lineage‐specific differentiation. Posttranslational modification of proteins via O‐GlcNAcylation is an ideal metabolic sensor, but how it contributes to megakaryopoiesis and thrombopoiesis remains unknown. Here, we reveal for the first time that cellular O‐GlcNAcylation levels decline along the course of megakaryocyte (MK) differentiation from human‐derived hematopoietic stem and progenitor cells (HSPCs). Inhibition of O‐GlcNAc transferase (OGT) that catalyzes O‐GlcNAcylation prolongedly decreases O‐GlcNAcylation and induces the acquisition of CD34⁺CD41a⁺ MK‐like progenitors and its progeny CD34⁻CD41a⁺/CD42b⁺ megakaryoblasts (MBs)/MKs from HSPCs, consequently resulting in increased CD41a⁺ and CD42b⁺ platelets. Using correlation and co‐immunoprecipitation analyses, we further identify c‐Myc as a direct downstream target of O‐GlcNAcylation in MBs/MKs and provide compelling evidence on the regulation of platelets by novel O‐GlcNAc/c‐Myc axis. Our data indicate that O‐GlcNAcylation posttranslationally regulates c‐Myc stability by interfering with its ubiquitin‐mediated proteasomal degradation. Depletion of c‐Myc upon inhibition of OGT promotes platelet formation in part through the perturbation of cell adhesion molecules, that is, integrin‐α4 and integrin‐β7, as advised by gene ontology and enrichment analysis for RNA sequencing and validated herein. Together, our findings provide a novel basic knowledge on the regulatory role of O‐GlcNAcylation in megakaryopoiesis and thrombopoiesis that could be important in understanding hematologic disorders whose etiology are related to impaired platelet production and may have clinical applications toward an ex vivo platelet production for transfusion.

How I Diagnose Low-Grade Myelodysplastic Syndromes

OBJECTIVES

Myelodysplastic syndromes (MDS) are a group of myeloid neoplasms that are often difficult to diagnose due to their pathologic and clinical heterogeneity. The key features of MDS are peripheral blood cytopenias, ineffective hematopoiesis manifesting as morphologic dysplasia, and clonal genetic abnormalities. The most difficult diagnostic dilemmas often arise in low-grade MDS cases (lacking excess blasts), which can be difficult to distinguish from other causes of cytopenia. This distinction requires the integration of information from the peripheral blood (both CBC parameters and morphology), bone marrow morphology, genetic studies, and interrogation of the clinical record to exclude secondary causes.

METHODS

We discuss the approach to the diagnosis of low-grade MDS (cases lacking increased blasts), including a diagnostic algorithm and two illustrative cases.

RESULTS

The appropriate use of ancillary studies is important to support or dispute the likelihood of low-grade MDS in conjunction with the findings of morphologic dysplasia. Interpreting the results of cytogenetics and next-generation sequencing can be challenging and must incorporate the emerging knowledge of clonal hematopoiesis of indeterminate potential.

CONCLUSIONS

The role of pathologists in integrating data from multiple sources in the diagnosis of low-grade MDS is evolving and becoming increasingly complex; in this challenging diagnostic setting, it is important to feel comfortable with uncertainty and maintain a conservative approach.

Presence of CD34+ in Megakaryocytes in Association With p53 Expression Predicts Unfavorable Prognosis in Low-risk Myelodysplastic Syndrome Patients

BACKGROUND/AIM

Although risk stratification using the Prognostic Scores Systems (IPSS, WPSS and IPSS-R) incorporate key information about prognosis of patients with Myelodysplastic syndromes (MDS), patients classified as low-risk may evolve rapidly and aggressively, despite a "favorable" prognostic stratification. The aim of this study was to identify biomarkers for predicting prognosis, and for better stratification and management of these patients.

MATERIALS AND METHODS

Expression of CD34 and p53 in megakaryocytes was examined by immunohistochemistry in 71 MDS patients classified as low-risk.

RESULTS

CD34 staining in megakaryocytes was associated with p53 expression (p=0.0166). CD34 and p53 expression were associated to worse overall survival in patients (p=0.0281).

CONCLUSION

The presence of CD34 in megakaryocytes is associated with p53 expression and an adverse prognosis for MDS patients.

The Novel Association of Circulating Tumor Cells and Circulating Megakaryocytes with Prostate Cancer Prognosis

Purpose: To develop an approach for the investigation of different subtypes of circulating tumor cells (CTC) and other cells to evaluate their potential prognostic value of prostate cancer.Experimental Design: Malignancy of CTCs undergoing epithelial-to-mesenchymal transition (EMT) was confirmed by repeated FISH. Subgroups of CTCs in 81 patients with prostate cancer (43 castration resistant and 38 untreated localized) were correlated to disease aggressiveness parameters. AUC analysis was applied to compare the performance for metastasis prediction between serum PSA level alone and a combined risk score using both PSA and EMTing CTC count. Circulating megakaryocytes and cancer patient survival association was performed using Cox model.Results: The majority of vimentin (VIM)⁺/CD45^- cells were malignant, with genomic alterations in several genomic regions. The number of cytokeratin (CK)^-/VIM⁺/CD45^- CTCs correlated with disease burden, tumor aggressiveness, and poorer survival. Meanwhile, CK⁺/VIM⁺/CD45^- CTCs were associated with metastases better than other subtypes of CTCs in these limited samples. Combination of PSA level and the number of CK⁺/VIM⁺/CD45^- CTCs enhanced the prediction of cancer metastases [AUC, 0.921; 95% confidence interval (CI), 0.858-0.985]. The number of circulating megakaryocytes was potentially associated with good patient survival in advanced prostate cancer (HR, 0.849; 95% CI, 0.628-1.146, per cell increase), and the difference between the number of mesenchymal CTCs and megakaryocytes strongly correlated to poor survival (HR, 10.17; 95% CI, 2.164-47.789, if score ≥2.0).Conclusions: This CTC analysis approach and the potential association of megakaryocytes with cancer prognosis may greatly enhance our ability to investigate the cancer metastasis process and to predict/monitor cancer progression. Clin Cancer Res; 23(17); 5112-22. ©2017 AACR.

S100 expression by atypical megakaryocytes: a previously unreported potential pitfall in dermatopathology

Several types of large atypical epithelioid cells can mimic tumoral melanocytes and can therefore be a source of misdiagnosis of melanoma. Megakaryocytes are one of these types, and are not frequently mentioned in the literature. In the current report, we present the case of a 76-year-old man presenting with acute panmyelosis with myelofibrosis. The bone marrow biopsy contained atypical megakaryocytes that expressed S100 in the cytoplasm. We discuss how such aberrant expression could be a source of some diagnostic problems in dermatopathology, including cutaneous melanoma, metastasis of melanoma in bone marrow and metastasis of melanoma in sentinel lymph nodes.