Biological Characteristics and Regulation of Early Megakaryocytopoiesis.

For decades, megakaryocytopoiesis is believed to occur following a classical binary hierarchical developmental model. This model is based on an analysis of predefined flow-sorted cell populations by using cell surface markers. However, this classical model has been challenged by increasing evidences obtained with new techniques which integrating flow cytometric, transcriptomic and functional data at single-cell level and with lineage tracing technique. These recent advances in megakaryocytopoiesis proposed that commitment of haematopoietic stem cells (HSCs) towards megakaryocytic lineage occurs in much earlier stage than that postulated in the classical model. There may exist multipotent but megakaryocyte (MK)/platelet-biased HSCs within HSC compartment and even HSCs can directly differentiate into MKs in steady state or in response to stress. In this review, we focus on recent findings about differentiation from commitment of HSCs to MK and its regulation, and discuss future directions in this research field.

Effects of vascular endothelial growth factors and their receptors on megakaryocytes and platelets and related diseases.

It is well known that vascular endothelial growth factors (VEGFs) and their receptors (vascular endothelial growth factor receptors, VEGFRs) are expressed in different tissues, and VEGF-VEGFR loops regulate a wide range of responses, including metabolic homeostasis, cell proliferation, migration and tubuleogenesis. As ligands, VEGFs act on three structurally related VEGFRs (VEGFR1, VEGFR2 and VEGFR3 [also termed FLT1, KDR and FLT4, respectively]) that deliver downstream signals. Haematopoietic stem cells (HSCs), megakaryocytic cell lines, cultured megakaryocytes (MKs), primary MKs and abnormal MKs express and secrete VEGFs. During the development from HSCs to MKs, VEGFR1, VEGFR2 and VEGFR3 are expressed at different developmental stages, respectively, and re-expressed, e.g., VEGFR2, and play different roles in commitment, differentiation, proliferation, survival and polyplodization of HSCs/MKs via autocrine, paracrine and/or even intracrine loops. Moreover, VEGFs and their receptors are abnormally expressed in MK-related diseases, including myeloproliferative neoplasms, myelodysplastic syndromes and acute megakaryocytic leukaemia (a rare subtype of acute myeloid leukaemia), and they lead to the disordered proliferation/differentiation of bone marrow cells and angiogenesis, indicating that they are closely related to these diseases. Thus, targeting VEGF-VEGFR loops may be of potential therapeutic value.

Effect of left atrial enlargement on expression of the angiotensinⅡ, signal transducers and activators of transcription 3 and Rac GTPase activating protein 1 signaling pathways in patients with persistent atrial fibrillation and rheumatic heart disease / 中国胸心血管外科临床杂志

@#Objective To evaluate the effect of left atrial enlargement on atrial myocardial fibrosis degree and levels of the angiotensinⅡ (AngⅡ)/Rac GTPase activating protein 1 (Rac1)/signal transducersand activators of transcription 3 (STAT3) signaling pathways expressing in patients with persistent atrial fibrillation and rheumatic heart disease (RHD). Methods From March to December 2011, 30 patients with RHD who underwent prosthetic valve replacement in our hospital were enrolled, including 16 males and 14 females, aged 42-70 (56.9±6.8) years. Twenty RHD patients with persistent atrial fibrillation as a research group and ten RHD patients with sinus rhythm as a control group (group A) underwent transthoracic echocardiography and right atrial appendage (RAA) tissue samples were obtained from these patients during mitral/aortic valve replacement operation. The research group according to left atrial diameter (LAD) was divided into two groups, ten patients in each group: a group B with LAD of 50–65 mm and a group C with LAD of LAD>65 mm. For each sample, histological examination was performed by hematoxylin-eosin and Masson’s trichrome staining. Light-microscopic pictures of atrial tissues samples were stained and tissue fibrosis degree in each group was analyzed. AngⅡ concentration was measured by enzyme linked immunosorbent assay. Rac1 and STAT3 were measured by western blotting. Results LAD was significantly greater in AF patients with RHD than in the control group. Hematoxylin-eosin staining demonstrated highly organized arrangement of atrial muscles in the control group and significant derangement in both group B and group C with reduced cell density and increased cell size. Moreover, Masson’s trichrome staining showed that atrial myocytes were surrounded by large trunks of collagen fibers in both group B and group C, but not in the group A. There was a positive correlation between atrial tissue fibrosis and LAD. AngⅡ content was positively correlated with LAD. Similarly, Rac1 and STAT3 protein levels were found considerably higher in the group C and group B than in the group A with excellent correlation to LAD. Conclusion In patients with RHD complicated with persistent atrial fibrillation, the degree of atrial fibrosis and the expression level of AngⅡ/Rac1/STAT3 signaling pathways significantly increase with the left atrialenlargement.

Large scale ex vivo expansion of clinical-grade effector cells for adoptive immunotherapy.

Cell-based adoptive immunotherapy for the treatment of various cancer types has attracted the attention of scientists. However, due to the absence of unitary standard protocols to produce large quantities of clinical-grade effector cells, it remains challenging to translate the experimental findings into clinical applications. The present study used methods complying with good manufacturing practice to induce effector cells from human peripheral blood mononuclear cells (PBMCs) of healthy donors by interleukin-2 and anti-Her-2 antibody with or without anti-CD3 antibodies (OKT3). The results indicated that the addition of OKT3 resulted in a greater expansion of the total cells and CD8+ T cells, and primarily induced the PBMCs to differentiate into CD3+ T cells. Regardless of the presence of OKT3, the expression of activating receptor of natural killer (NK) group 2, member D, and the inhibitory receptors of CD158a and CD158b on NK cells and NKT cells was increased, while the expression of NKp46 was inhibited on NK cells, but not on NKT cells. Furthermore, OKT3 did not affect the toxicity of the effector cells. Subgroup analysis indicated that although a variation of the composition of effector cells was present in different individuals under identical culture conditions, consistent marker expression on effector cells and target cell-killing effects were observed in different subgroups treated with or without OKT3. Furthermore, western blot analysis indicated that OKT3, apart from its involvement in cell cycle regulation, affects transcription and protein translation during processes of proliferation and differentiation. The present study provided experimental data regarding the production of effector cells for adoptive immunotherapy as a clinical application.

[Protein kinase A inhibitor H-89 blocks polyploidization of SP600125-induced CMK cells by regulating phosphorylation of ribosomal protein S6 kinase 1].

Objective To investigate the regulatory effect of post-translation modification of ribosomal protein S6 kinase 1 (S6K1) on the polyploidization of megakaryocytes. Methods SP600125, a c-Jun N-terminal kinase (JNK) inhibitor, and H-89, a cAMP-dependent protein kinase (PKA) inhibitor, were used to treat CMK cells separately or in combination. With propidium iodide (PI) to dye DNA in the treated cells, the relative DNA content was detected by flow cytometry, and then the DNA polyploidy was analyzed. The change of expression and phosphorylation of ribosomal protein S6 kinase 1 (S6K1), an important mammalian target of rapamycin (mTOR) downstream target molecule, was analyzed by Western blotting. Molecular docking study and kinase activity assay were performed to analyze the combination of H-89 with S6K1 and the effect of H-89 on the activity of S6K1 kinase. Results SP600125 induced CMK cell polyploidization in a time-dependent and dose-dependent manner. At the same time, it increased the phosphorylation of S6K1 at Thr421/Ser424 and decreased the phosphorylation of S6K1 at Thr389. H-89 not only blocked polyploidization, but also decreased the phosphorylation of S6K1 at Thr421/Ser424 and increased the phosphorylation of S6K1 at Thr389. Molecular docking and kinase activity assay showed that H-89 occupied the ATP binding sites of S6K1 and inhibited its activity. Noticeably, both H-89 and SP600125 inhibited the activity of PKA. Moreover, the two drugs further inhibited the activity of PKA when used together. Therefore, these data indicated that H-89 blocked the SP600125-induced polyploidization of CMK cells mainly by changing S6K1 phosphorylation state, rather than its inhibitory effect on PKA. Conclusion H-89 can block the polyploidization of SP600125-induced CMK cells by regulating S6K1 phosphorylation state.

[SP600125-induced polyploidization of megakaryocytic leukemia cell lines by ribosomal protein S6 kinase 1 depends on the degree of cell differentiation].

Objective To investigate regulatory role of ribosomal protein S6 kinase 1 (S6K1) in the polyploidization of different megakaryocytic leukemia cell lines at the different differentiation stages. Methods Megakaryocytic leukemia cell lines (Dami, Meg-01 and HEL cells) were induced towards polyploidization by SP600125, a c-Jun N-terminal kinase (JNK) inhibitor. The SP600125-inducing process was blocked by H-89, a cAMP-dependent protein kinase (PKA) inhibitor. The phenotype (CD41a, CD42a and CD42b) and DNA ploidy were detected by flow cytometry. The expression and phosphorylation of S6K1 and related proteins were detected by Western blotting. Results SP600125 induced polyploidization and increased the phosphorylation of eukaryotic initiation factor 4E binding protein 1 (4E-BP1) in Dami, Meg-01 and HEL cells. However, the effect of SP600125 on polyploidization of the three cell lines was different, with the strongest effect on Dami cells and the weakest on Meg-01 cells. Moreover, SP600125 increased the phosphorylation of S6K1 Thr421/Ser424 and decreased the phosphorylation of Thr389 in Dami cells. However, it only increased the phosphorylation of Thr389 in HEL cells and had no effect on the phosphorylation of S6K1 in Meg-01 cells. Interestingly, H-89 only partially blocked the polyploidization of Dami cells, although it decreased the phosphorylation of 4E-BP1 in all SP600125-induced three cell lines. Noticeably, H-89 decreased the phosphorylation of S6K1 Thr421/Ser424 and increased the phosphorylation of Thr389 in Dami cells. However, H-89 had no effect on the phosphorylation of Thr421/Ser424, although it increased the phosphorylation of Thr389 in Meg-01 and HEL cells. Phenotypic analysis showed that the three cell lines were at different levels of differentiation in megakaryocytic lineage, with the highest differentiation in Dami and the lowest in Meg-01 cells. Conclusion SP600125-induced polyploidization of megakaryocytic leukemia cell lines is dependent on the effect of SP600125 on phosphorylation of S6K1 in cell lines at the different differentiation stages.

Effect of autologous bone marrow cell transplantation combined with off-pump coronary artery bypass grafting on cardiac function in patients with chronic myocardial infarction.

OBJECTIVES: This study aimed to investigate the feasibility and effects of intramuscular injections of autologous bone marrow cells (BMC) combined with off-pump coronary artery bypass grafts (OPCAB) on improving cardiac function in chronic myocardial infarction patients. METHODS: Ninety patients with chronic myocardial infarction were prospectively enrolled and randomized to an OPCAB with saline or an OPCAB with BMC-treatment group. After finishing CABG, patients received injections of BMC or saline into the marginal area of the infarct. The primary endpoint was incidence of emergent adverse events within 6 months. RESULTS: There were no differences between the control and BMC-treated groups in baseline ejection fractions (EF) or wall motion score indices (WMSI) in the affected segments. At the 6-month follow-up, the ejection fraction was significantly increased in the BMC-treated group compared to controls (47.58 ± 6.34 vs. 40.11 ± 7.42; p < 0.05), whereas the WMSI were significantly decreased (1.25 ± 0.32 vs. 1.54 ± 0.53; p < 0.05), with no occurrences of life-threatening arrhythmias or death. The addition of BMC injections to OPCAB treatment increased regional perfusion to the marginal infarct area. CONCLUSION: These results demonstrate that BMC transplant is beneficial to the cardiac function with no adverse effects, and therefore a safe and feasible adjunct therapy providing beneficial effects in clinical practice.

Phosphorylation of ribosomal protein S6 kinase 1 at Thr421/Ser424 and dephosphorylation at Thr389 regulates SP600125-induced polyploidization of megakaryocytic cell lines.

Megakaryocytes (MKs) are one of the few cell types that become polyploid; however, the mechanisms by which these cells are designated to become polyploid are not fully understood. In this investigation, we successfully established two relatively synchronous polyploid cell models by inducing Dami and CMK cells with SP600125. We found that SP600125 induced the polyploidization of Dami and CMK cells, concomitant with the phosphorylation of ribosomal protein S6 kinase 1 (S6K1) at Thr421/Ser424 and dephosphorylation at Thr389. The polyploidization was partially blocked by H-89, a cAMP-dependent protein kinase (PKA) inhibitor, through direct binding to S6K1, leading to dephosphorylation at Thr421/Ser424 and phosphorylation at Thr389, independent of PKA. Overexpression of a rapamycin-resistant mutant of S6K1 further enhanced the inhibitory effect of LY294002 on the SP600125-induced polyploidization of Dami and CMK cells. SP600125 also induced the polyploidization of Meg-01 cells, which are derived from a patient with chronic myelogenous leukemia, without causing a significant change in S6K1 phosphorylation. Additionally, SP600125 induced the polyploidization of HEL cells, which are derived from a patient with erythroleukemia, and phosphorylation at Thr389 of S6K1 was detected. However, the polyploidization of both Meg-01 cells and HEL cells as a result of SP600125 treatment was lower than that of SP600125-induced Dami and CMK cells, and it was not blocked by H-89 despite the increased phosphorylation of S6K1 at Thr389 in both cell lines in response to H-89. Given that the Dami and CMK cell lines were derived from patients with acute megakaryocytic leukemia (AMKL) and expressed high levels of platelet-specific antigens, our data suggested that SP600125-induced polyploidization is cell-type specific, that these cell lines were more differentiated, and that phosphorylation at Thr421/Ser424 and dephosphorylation at Thr389 of S6K1 may play an important role in the SP600125-induced polyploidization of these cell lines synergistically with other signaling pathways.

[Thymoglobulin efficiently expands cytokine-induced killer cells in a clinical-grade culture protocol].

OBJECTIVE: To study the effect of thymoglobulin (TG) on proliferation, immune cell phenotype and cytotoxicity of cytokine-induced killer (CIK) cells in a clinical-grade culture protocol. METHODS: Peripheral blood mononuclear cells (PBMCs) isolated from 11 healthy donors were primed with IFN-γ on day 0 and treated with either TG or CD3 mAb on day 1. Thereafter, the cells were fed with IL-2 every 3 days until day 21. Aliquots of cells were harvested weekly. The cell number and viability were measured using trypan blue exclusion. The expressions of CD3, CD4, CD8, CD16/CD56, NK activating/inhibitory receptor, and the CD25⁺ Foxp3⁺ regulatory T cells (Tregs) were analyzed with flow cytometry. The cytotoxicity of CIK cells against K562 cells were determined by lactate dehydrogenase (LDH) release assay on day 16 and day 21. RESULTS: Both TG and CD3 mAb stimulated the growth of CIK cells. However, the effect of CD3 mAb was weaker than that of TG. Flow cytometric analysis showed that the percentages of CD3⁺ CD16⁺ CD56⁺ cells and CD3⁻ CD16⁺ CD56⁺ cells and the expression of NK activating/inhibitory receptor recovered and increased continuously until the end of culture (day 21) following a transient decrease at day 7. Noticeably, on day 7, 14 and 21, the percentages of CD3⁺ CD 16⁺ CD56⁺ cells and CD3⁻ CD16⁺ CD56⁺ cells as well as the expression of NK activating/inhibitory receptor were higher in TG-induced CIK cells than those in CD3 mAb-induced CIK cells (P<0.05); Moreover, LDH release assay revealed that the cytotoxicity of CIK cells against K562 cells in TG-induced CIK cells was significantly higher than that of CD3 mAb-induced CIK cells (P<0.05). In both CD3 mAb-induced CIK cell culture system and TG-induced CIK cell culture system, Treg increased transiently at day 7; moreover, the percentage of Treg in TG-induced CIK cells was significantly higher than that of CD3 mAb-induced CIK cells (P<0.05). In addition, both CD3 mAb and TG reduced the percentage of CD3⁺ CD4⁺ cells continuously, meanwhile increased the percentage of CD3⁺ CD8⁺ cells. There was no significant difference in the changes of CD3⁺ CD4⁺ cells and CD3⁺ CD8⁺ cells between the two CIK cell culture systems. CONCLUSION: Compared with CD3 mAb, TG more selectively expanded CD3⁺ CD16⁺ CD56⁺ cells and CD3⁻ CD16⁺ CD56⁺ cells (CIK effector cells) and promoted the differentiation and maturation of these CIK effector cells with more powerful cytotoxic activity. Therefore, it is feasible for TG to substitute CD3 mAb to prepare the clinical grade products of CIK cells. Both CD3 mAb and TG increased negative regulatory cells, Tregs, transiently in CIK culture system and depleting or reducing Tregs might be helpful for increasing the production efficacy of the main effector cells in CIK cells.

[Autologous CIK cell infusion promotes amplification ability of CD3⁺ CD56⁺ cells when re-preparation from patients with malignant tumors].

OBJECTIVE: To investigate the effects of the autologous cytokine-induced killer (CIK) cell infusion on the subpopulation distribution and activity of the CIK cells from the patients with malignant tumors when prepared in the same liquid culture system again. METHODS: A total of 201 patients who gave a written consent and received 2 courses of therapeutic infusion of CIK cells were divided into ≤ 90-day group in which the secondary preparation of CIK cells was performed in less than 90 days after the primary infusion and >90-day group in which the secondary preparation of CIK cells was performed in more than 90 days after the primary infusion. The proliferation and subtypes, including CD3⁺ cells, CD3⁺ CD4⁺ cells, CD3⁺ CD8⁺ cells, and CD3⁺ CD56⁺ cells, of CIK cells were analyzed by hemocytometer with trypan blue exclusion and flow cytometry, respectively. The expression of NKG2D receptor was also detected using flow cytometry. The cytotoxicity against K562 cells was analyzed using lactate dehydrogenase (LDH) release. RESULTS: The percentage of CD3⁺ CD56⁺ cell subpopulation in the secondary preparation of CIK cells in ≤ 90-day group [(16.7 ± 9.1)%] was higher than that in the primary preparation of CIK cells [(13.5 ± 8.6)%] (P<0.01). Furthermore, the percentage of NKG2D in the secondary CIK cell preparation [(84.1 ± 10.8)%] was significantly higher than that in the primary CIK cell preparation [(81.1 ± 14.8)%] in ≤ 90-day group (P<0.05). In contrast, the percentage of CD3⁺ CD4⁺ cells in the secondary CIK cell preparation [(15.2 ± 9.7)%] was significantly lower than that in the primary CIK cell preparation [(17.6 ± 12.5)%] (P<0.01). However, no significant differences in CD3⁺ CD56⁺ cell subpopulation and expression of NKG2D was detected between the primary and secondary CIK cell preparation in >90 d group, although the percentage of CD3⁺ CD4⁺ cells in the secondary CIK cell preparation [(14.5 ± 9.4)%] was significantly lower than that in the primary CIK cell preparation [(18.2 ± 12.9)%] (P<0.01). In addition, no significant differences in total cell number and cytotoxic activity against K562 cells between the primary and secondary CIK cell preparation was detected either in >90-day group or in ≤ 90-day group. CONCLUSION: CIK cell infusion can facilitate and enhance the proliferation and differentiation of the precursor cells of the CD3⁺ CD56⁺ subpopulation in the same CIK cell culture system and this effect does not last more than 90 days, suggesting that the secondary CIK cell infusion should be performed within 90 days in order to obtain the better therapeutic efficacy.

Rosiglitazone amplifies the sensitivity of docetaxel and reduces the expression of CD44v6.

Breast cancer seriously impairs physical and mental health in females. Currently, with further investigation into drugs, a number of new pharmacological effects have been found that offer new methods for clinical application in the treatment of breast cancer. As a widely used antidiabetic drug, rosiglitazone (Ros) has become well known for its anticancer effects, mediated by the activation of peroxisome proliferator-activated receptor γ and downregulated expression of the associated invasion gene. The objective of the present study was to investigate the combination of Ros and docetaxel (DOC) and whether DOC has any effect on breast cancer cell lines. The results showed that the combination of Ros and DOC may cooperate to increase anti-growth efficacy. The additive inhibitory effects on cell proliferation were sequence-dependent and are not likely to be associated with cell cycle arrest. This suggested that the target activation of associated factors of the signaling pathway by Ros may be a compelling ally in cancer treatment. In addition, evidence was provided for a convergence of Ros and DOC to induce the reduced expression of CD44v6. Future studies are required to confirm which associated gene of Ros is significant in blocking the signaling pathway.

SU6668 suppresses proliferation of triple negative breast cancer cells through down-regulating MTDH expression.

BACKGROUND: The multiple tyrosine kinase inhibitors SU6668 have a promising therapeutic effect on the progression of hematological malignancies and some solid tumors. Here, we determined its effect on triple negative breast cancer (TNBC) cells and explored the potential molecular mechanism. METHODS: In this study, MDA-MB-231 cells were treated with SU6668 (15 µM, 30 µM) for 72 h and the change of proliferation was examined by MTT and tablet cloning. DNA ploidy was detected by flow cytometric analysis with PI staining. Double-label immunofluorescence method was used to detect the expression and distribution of MTDH proteins. VEGFR2, HIF-1α, MTDH, E-cadhrein, and SMA expressions were detected by Western bolt assay. RESULTS: This study showed that SU6668 inhibited the proliferation and induced polyploidization of MDA-MB-231 cells in a dose dependent form. SU6668 exposure increased the distribution of MTDH in cytoplasm and decreased its distribution in nuclei. After the treatment of SU6668, VEGFR2, HIF-1α, MTDH and SMA proteins were down-regulated, while E-cadhrein was up-regulated in MDA-MB-231 cells. CONCLUSIONS: In conclusion, SU6668 exposure maybe induces polyploidization, inhibit EMT and influence the expression of MTDH, which suppresses the proliferation in TNBC cells. MTDH is a key signal protein in downstream of VEGF/HIF-1αpathway in MDA-MB-231 cells, which may be used as the potential target in the treatment of TNBC.

[Autologous cytokine-induced killer cells therapy on the quality of life of patients with breast cancer after adjuvant chemotherapy: a prospective study].

OBJECTIVE: To explore the effect of autologous cytokine-induced killer cells on the quality of life in patient with breast cancer who have already finished the adjuvant chemotherapy. METHODS: One hundred and twenty-eight postoperative patients with breast cancer who underwent anthracycline-based adjuvant chemotherapy were enrolled in this prospective study, and they were randomized into 2 groups, i.e., treatment group, which received the therapy of CIK cells transfusion, and control group, which was given regular follow-up. Meanwhile, patients with positive hormone receptor in the two groups were given endocrine therapy, and the patients with positive axillary lymph nodes were given radiotherapy to the chest wall and regional lymph nodes. The difference of quality of life between the two groups was analyzed according to the EORTC QLQ-BR53 quality of life questionnaire, and the adverse reactions were monitored. RESULTS: As regarding the functional evaluation, the physical function scores of patients of the treatment group were (83.43 ± 14.87) and (88.55 ± 11.62) at 3 and 6 months after the CIK cell therapy, respectively, significantly higher than the baseline value [(74.83 ± 13.82), P < 0.05)]. Global health status/QOL scores were (83.30 ± 19.09) and (89.68 ± 10.81), significantly higher than the baseline value [(77.72 ± 21.05), P < 0.05]. As regarding symptoms, the scores of fatigue, nausea, vomiting and loss of appetite of patients in the treatment group were higher than the baseline value, with significant differences (P < 0.05). The nausea and vomiting scores in the control group at 3 and 6 months of followed-up were (26.67 ± 22.56) and (21.47 ± 21.06), significantly lower than the baseline values [(33.31 ± 27.07), P < 0.05]. The scores of worrying about the future in the patients of treatment group were (47.56 ± 30.84) and (42.33 ± 26.95) after 3 and 6 months, significantly better than the baseline value [(57.41 ± 30.63), P < 0.05]. The systematic therapy side effects scores were (31.95 ± 27.52) and (23.72 ± 22.87), significantly better than the baseline value [(40.56 ± 26.28), P < 0.05]. The scores of arm edema were (45.26 ± 25.42) and (36.61 ± 20.51), significantly milder than the baseline value [(55.11 ± 22.82), P < 0.05]. In the control group, the scores of arm edema were (44.85 ± 28.94) and (38.64 ± 23.68), significantly lower than the baseline values [(53.26 ± 23.84) points, P < 0.05]. Alopecia scores were (29.93 ± 24.72) and (24.18 ± 22.66), significantly lower than the baseline values [(35.92 ± 22.08), P < 0.05]. In the treatment group, the patients' physical function, social function and global health status/QOL, fatigue, insomnia, and worrying about the future rates were significantly higher than that of the control group (P < 0.05 for all). Three patients after CIK reinfusion had transient fever, and 6 cases felt pain in the lower limb, but the symptoms were relieved after symptomatic treatment. CONCLUSIONS: Therapy of autologous CIK cells transfusion can significantly improve the quality of life of breast cancer patients, and the adverse reactions during the treatment can be alleviated by symptomatic treatment.

[mTOR/p70s6k signaling pathway is involved in megakaryocyte polyploidization].

AIM: To investigate the mechanisms of megakaryocyte polyploid cell cycle control. METHODS: The expression and phosphorylation of mTOR/p70s6k pathway proteins was detected by western blot. Double-labeling techniques were used to investigate in which of the phase of the polyploid cell cycle S6K1 at Thr421/Ser424 are phosphorylated. RESULTS: Nocodazole induced a relatively synchronized polyploidization in Dami cells. The expression of mTOR and the phosphorylation of mTOR at Ser2448 increased when Dami cells begin to progress from G1 to S-phase in cell cycle. Analysis of flow cytometry showed that phosphorylation of S6K1 at Thr421/Ser424 increased at G2/M-phase. CONCLUSION: mTOR/S6K1 pathway is involved in megakaryocyte polyploid cell cycle control.

S6K1 is involved in polyploidization through its phosphorylation at Thr421/Ser424.

Studies on polyploidization of megakaryocytes have been hampered by the lack of synchronized polyploid megakaryocytes. In this study, a relatively synchronized polyploid cell model was successfully established by employing Dami cells treated with nocodazole. In nocodazole-induced cells, cyclin B expression oscillated normally as in diploid cells and polyploid megakaryocytes. By using the nocodazole-induced Dami cell model, we found that 4E-BP1 and Thr421/Ser424 of ribosomal S6 kinase 1(S6K1) were phosphorylated mostly at M-phase in cytoplasm and oscillated in nocodazole-induced polyploid Dami cells, concomitant with increased expression of p27 and cyclin D3. However, phosphorylation of 4E-BP1 and S6K1 on Thr421/Ser424 was significantly decreased in differentiated Dami cells induced by phorbol 12-myristate 13-acetate (PMA), concomitant with increased expression of cyclin D1 and p21 and cyclin D3. Overexpression of the kinase dead form of S6K1 containing the mutation Lys 100 --> Gln in PMA-induced Dami cells increased ploidy whereas overexpression of rapamycin-resistant form of S6K1 containing the mutations Thr421 --> Glu and Ser424 --> Asp significantly dephosphorylated 4E-BP1 and reduced expression of cyclin D1, cyclin D3, p21 and p27, and slightly decreased the ploidy of PMA-induced Dami cells, compared with treatment with PMA alone. Moreover, overexpression of rapamycin-resistant form of S6K1 significantly reversed polyploidization of nocodazole-induced Dami cells. Furthermore, MAP (a novel compound synthesized recently) partly blocked the phosphorylation of S6K1 on Thr421/Ser424 and decreased the expression of p27 and polyploidization in nocodazole-induced Dami cells. Taken together, these data suggested that S6K1/4E-BP1 pathway may play an important role in polyploidization of megakaryocytes.

Identification and characterization of the CD226 gene promoter.

CD226 is one of the main activating receptors on natural killer cells, and it can induce cytotoxicity to target cells through interaction with its ligands CD155 or CD112. CD226 is also involved in T cell differentiation, activation, and cytotoxicity. The expression of CD226 on natural killer cells and T cells can be regulated by cytokines and chemical stimuli; however, the mechanism of the regulation of the CD226 gene is still unknown. In this study, we have identified two promoters in the human CD226 gene named P1 and P2, which are located at -810 to -287 bp and +33 to +213 bp, respectively, and a negative regulation element between P1 and P2. Both P1 and P2 can be regulated by phorbol ester (12-O-tetradecanoylphorbol-13-acetate) and calcium ionophore (A23187). Bioinformatics analysis shows that, within this CD226 gene region, there are putative binding sites for transcription factors AP-1, Sp1, PEA3, and Ets-1. We have found that transcription factor activating protein-1 (AP-1) can up-regulate CD226 promoters P1 and P2 in human hepatocarcinoma cells, a hepatocarcinoma cell line with low expression of endogenous AP-1 and Ets-1. Interestingly, the transcription factor Ets-1 promotes AP-1-induced P2 activity but inhibits AP-1-induced P1 activity for which a 10-bp AP-1/Ets-1 composite site (CCTTCCTTCC) in P1 may be responsible.

[The proliferation, phenotype change and anti-tumor activity of cytokine induced killer cells].

AIM: To study the growth regularity, the phenotype change and the cytotoxicity of CIK cells. METHODS: The number of CIK cells was counted by living cell counting in different culturing time to observe the growth of the CIK cells, and the phenotype change of the CIK cells was detected by flow cytometry. Meanwhile cytotoxicity of CIK cells to tumor cell lines was also detected by CytoTox96 non-radiated cytotoxicity kit. RESULTS: After stimulated by cytokines and anti-CD3 antibody, CIK cells can proliferate significantly. The cell number of CIK was increased to 473.28+/-27.53 fold in serum-free medium plus auto-serum, 218.24+/-16.86 fold in serum-free medium and only 11.52+/-1.04 fold in RPMI1640 plus fetal FCS, respectively. The CD3(+)+CD8(+), CD3(+)+CD56(+), CD226(+)+CD11a(+) and CD305(+)+CD11a(+) cells were increased with the progression of the cultural time and the CD3(+)+CD4(+) cells were decreased with the progression of cultural time. The cytotoxicity of CIK cells to tumor cell lines was significantly higher than that of LAK cells (P<0.01) and its cytotoxicity was increased with progression of the cultural time. CONCLUSION: CIK cells have strong proliferative ability and higher cytotoxicity to tumor cells in vitro, which could be used as a potential anti-tumor adoptive immunotherapy in clinic.

CD226 is expressed on the megakaryocytic lineage from hematopoietic stem cells/progenitor cells and involved in its polyploidization.

OBJECTIVES: In this study, we examined the expression of CD226 on megakaryocytic, granulocytic and erythroid lineage from hematopoietic stem cells/progenitor cells in adult and fetus and its potential role in megakaryocytic maturation. METHODS: CD34(+) cells from adult and fetus were induced to differentiate toward the megakaryocytic lineage by thrombopoietin (TPO) and the granulocytic lineage by granulocyte colony-stimulating factor (G-CSF), respectively. Mononuclear cells from fetal liver and CD34(+) cells from adult were induced to differentiate toward erythroid-lineage by erythropoiesis (EPO). We investigated the expression of CD226 and lymphocyte function associated antigen-1 (LFA-1) (CD11a) during hemopoiesis. We also studied the effect of CD226 monoclonal antibody (MoAb) and LFA-1 MoAb on megakaryocyte with antibody cross-liking technique. RESULTS: CD34(+) cells from adult and fetus and TPO-induced CD41(+) cells all expressed CD226 molecule. CD226 was not expressed on erythroid progenitor cells and erythroblasts and most cells of granulocytic lineage although G-CSF induced a significant increase of the expression of CD226 on CD34(+) cells in early period of time. CD226 MoAb acts on megakaryocytes by inducing intracellular calcium mobilization. The expression of LFA-1 decreased significantly at late stage of differentiation and maturation of fetal megakaryocytes whereas the expression of LFA-1 on adult megakaryocytes retained at a high level. CD226 MoAb in combination with LFA-1 MoAb shifted the ploidy of generated megakaryocytes from adult-derived CD34(+) cells to higher classes significantly although CD226 and LFA-1 MoAb slightly increased the ploidy of the generated megakaryocytes individually. CD226 MoAb or LFA-1 MoAb or CD226 MoAb plus LFA-1 MoAbs did not increase the ploidy of the generated megakaryocytes from fetus-derived CD34(+) cells. CONCLUSION: CD226 molecules play an important role in maturation of the megakaryocytes in combination with LFA-1.

9.1C3 is identical to LAIR-1, which is expressed on hematopoietic progenitors.

The leukocyte-associated Ig-like receptor-1 (LAIR-1) is a negative regulator of natural killer (NK) cells, its encoding gene belonging to the leukocyte receptor complex (LRC). Antibody to LAIR-1 can inhibit Ab-induced redirected lysis and TNF-alpha release of effector cells. LAIR-1 contains 2 immunoreceptor tyrosine-based inhibitory motifs (ITIM) in its cytoplasmic region that have been shown to bind constitutively and presumably regulate the tyrosine phosphatase SHP-1 in hematopoietic cells. SHP-1 mutation in mice results in abnormal lymphoproliferation, suggesting that LAIR-1 may also be implicated in regulating hematopoiesis. Here we investigated a monoclonal antibody, 9.1C3, against a NK cell antigen previously described as inducing increased colony formation in in vitro assays of human bone marrow cells. We found that 9.1C3 was expressed on CD34 positive hematopoietic progenitors for the first time. In functional assays, 9.1C3 MAb was able to inhibit Ab-induced redirected lysis and TNF-alpha secretion of NK cells. We proved that 9.1C3 is identical to LAIR-1, based on the fact that not only the antigen precipitated by 9.1C3 MAb was of 40kDa but also 9.1C3 MAb bound specifically to LAIR-1 cDNA transfected COS7 cells as well as recognized LAIR-1 fusion protein in ELISA. This finding provided the first evidence that LAIR-1 expresses on hematopoietic progenitor, implicating its role in the regulation of hematopoiesis at early stage.