Circulating mitochondrial DNA is associated with anemia in newly diagnosed hematologic malignancies.

Recent reports discovered that red blood cells (RBCs) could scavenge cell-free mitochondrial DNA (mtDNA), which drives the accelerated erythrophagocytosis and innate immune activation characterized by anemia and inflammatory cytokine production. However, the clinical value of the circulating mtDNA copy number alterations in hematologic malignancies is poorly understood. Our data showed that in comparison to healthy group, the patients group had significantly higher mtDNA and histone H4 levels. Moreover, we observed that RBC-bound mtDNA and histone H4 were negatively correlated with hemoglobin in patients. In addition, cytokines and chemokines levels in patients differed significantly from normal controls (21 higher, 7 lower). Our study suggested that both circulating mtDNA and histone H4 were associated with anemia in hematologic malignancies, which helps to further understand the potential mechanism of anemia development in patients with hematologic malignancies. This information may play a vital role in the specific therapeutic interventions for leukemia in the future.

Heparanase Facilitates PMA-Induced Megakaryocytic Differentiation in K562 Cells via Interleukin 6/STAT3 Pathway.

Heparanase (HPSE) is an endo-ß-D-glucuronidase that cleaves heparan sulfate and hence participates in remodeling of the extracellular matrix, leading to release of cytokines that are immobilized by binding to heparan sulfate proteoglycans (HSPGs), and consequently activating signaling pathways. This function of HPSE is correlated to its expression level that is normally very low in majority of the tissues. Exceptionally, human platelets express high level of HPSE, suggesting a unique physiological role in this cell. Using K562 cell line, we found a progressive increase of HPSE during the megakaryocytic differentiation. Analysis of a series of megakaryocytic differentiation-related heparin-binding proteins (HBPs) in the cell culture medium revealed an exclusive positive correlation between the level of interleukin 6 (IL-6) and HPSE expression. IL-6 modulated megakaryocytic differentiation through activation of STAT3. Further, we demonstrated that overexpression of HPSE potentiates megakaryocytic differentiation, whereas elimination of HPSE led to a delayed differentiation. This function of HPSE is associated with its activity, as overexpression of inactive HPSE had no effect on IL-6 production and megakaryocytic differentiation. The role of HPSE is further supported by the observation in an umbilical cord blood CD34+ cells megakaryocytic differentiation model. Our data propose a novel role for HPSE in platelets production by a HPSE/IL-6/STAT3 positive feedback loop that specifically regulates megakaryocytes maturation.

Overexpression of heparanase in mice promoted megakaryopoiesis.

Heparanase, an endo-glucuronidase that specifically cleaves heparan sulfate (HS), is upregulated in several pathological conditions. In this study, we aimed to find a correlation of heparanase expression and platelets production. In the transgenic mice overexpressing human heparanase (Hpa-tg), hematological analysis of blood samples revealed a significantly higher number of platelets in comparison with wild-type (Ctr) mice, while no significant difference was found in leukocytes and red blood cell number between the two groups. Total number of thiazole orange positive platelets was increased in Hpa-tg vs. Ctr blood, reflecting a higher rate of platelets production. Concomitantly, megakaryocytes from Hpa-tg mice produced more and shorter HS fragments that were shed into the medium. Further, thrombopoietin (TPO) level was elevated in the liver and plasma of Hpa-tg mice. Together, the data indicate that heparanase expression promoted megakaryopoiesis, which may be through upregulated expression of TPO and direct effect of released HS fragments expressed in the megakaryocytes.

The acid-sensing ion channel, ASIC2, promotes invasion and metastasis of colorectal cancer under acidosis by activating the calcineurin/NFAT1 axis.

BACKGROUND: The tumor acidic microenvironment, a common biochemical event in solid tumors, offers evolutional advantage for tumors cells and even enhances their aggressive phenotype. However, little is known about the molecular mechanism underlying the acidic microenvironment-induced invasion and metastasis. METHODS: We examined the expression of the acid-sending ion channel (ASIC) family members after acidic exposure using RT-PCR and immunofluoresence. Gene manipulation was applied to reveal the potential of ASIC2 on invasion, proliferation, colony formation of colorectal cancer (CRC). We assessed the in vivo tumor growth by subcutaneous transplantation and metastasis by spleen xenografts. Chromatin immunoprecipitation-sequencing was used to uncover the binding sites of NFAT1. Finally, we examined the expression of ASIC2 in CRC tissues using immunohistochemistry. RESULTS: Acidic exposure led to up-regulation of the acid-sensing ion channel, ASIC2, in colorectal cancer (CRC) cells. ASIC2 overexpression in CRC cell lines, SW480 and HCT116, significantly enhanced cell proliferation in vitro and in vivo, while ASIC2 knockdown had the reverse effect. Importantly, ASIC2 promoted CRC cell invasion under acidosis in vitro and liver metastasis in vivo. Mechanistically, ASIC2 activated the calcineurin/NFAT1 signaling pathway under acidosis. Inhibition of the calcineurin/NFAT pathway by cyclosporine A (CsA) profoundly attenuated ASIC2-induced invasion under acidosis. ChIP-seq assay revealed that the nuclear factor, NFAT1, binds to genes clustered in pathways involved in Rho GTPase signaling and calcium signaling. Furthermore, immunohistochemistry showed that ASIC2 expression is increased in CRC samples compared to that in adjacent tissues, and ASIC2 expression correlates with T-stage, distant metastasis, recurrence, and poor prognosis. CONCLUSION: ASIC2 promotes metastasis of CRC cells by activating the calcineurin/NFAT1 pathway under acidosis and high expression of ASIC2 predicts poor outcomes of patients with CRC.

Gemcitabine-induced heparanase promotes aggressiveness of pancreatic cancer cells via activating EGFR signaling.

Pancreatic cancer (PC), characterized by aggressive local invasion and metastasis, is one of the most malignant cancers. Gemcitabine is currently used as the standard drug for the treatment of advanced and metastatic PC, but with limited efficacy. In this study, we demonstrated that gemcitabine increased the expression of heparanase (HPA1), the only known mammalian endoglycosidase capable of cleaving heparan sulfate, both in vitro and in vivo. Furthermore, overexpression of HPA1 in PC cell lines enhanced proliferation and invasion, accompanied with elevated phosphorylation of EGFR. In addition, we showed that the NF-κB pathway mediated the gemcitabine-induced HPA1 expression. Importantly, we found that an HPA1 inhibitor attenuated gemcitabine-induced invasion of PC cells. Finally, we showed that HPA1 was of negative prognostic value for PC patients. Taken together, our results demonstrated that gemcitabine-induced HPA1 promotes proliferation and invasion of PC cells through activating EGFR, implying that HPA1 may serve as promising therapeutic target in the treatment of PC.