Lingyan Ping

Histone deacetylase 6 activity is critical for the metastasis of Burkitt?s lymphoma cells

BackgroundBurkitt’s lymphoma is an aggressive malignancy with high risk of metastasis to extranodal sites, such as bone marrow and central nervous system. The prognosis of metastatic Burkitt’s lymphoma is poor. Here we sought to identify a role of histone deacetylase 6 (HDAC6) in the metastasis of Burkitt’s lymphoma cells.MethodsBurkitt’s lymphoma cells were pharmacologically treated with niltubacin, tubacin or sodium butyrate (NaB) or transfected with siRNAs to knock down the expression of HDAC6. Cell migration and invasion ability were measured by transwell assay, and cell cycle progression was analyzed by flow cytometry. Cell adhesion and proliferation was determined by CellTiter-Glo luminescent cell viability assay kit. Cell morphological alteration and microtubule stability were analyzed by immunofluorescence staining. Effect of niltubacin, tubacin and NaB on acetylated tubulin and siRNA efficacy were measured by western blotting.ResultsSuppression of histone deacetylase 6 activity significantly compromised the migration and invasion of Burkitt’s lymphoma cells, without affecting cell proliferation and cell cycle progression. Mechanistic study revealed that HDAC6 modulated chemokine induced cell shape elongation and cell adhesion probably through its action on microtubule dynamics.ConclusionsWe identified a critical role of HDAC6 in the metastasis of Burkitt’s lymphoma cells, suggesting that pharmacological inhibition of HDAC6 could be a promising strategy for the management of metastatic Burkitt’s lymphoma.

Safety and efficacy of bevacizumab combined with R-CHOP regimen in seven Chinese patients with untreated diffuse large B-cell lymphoma.

BackgroundRituximab plus CHOP (R-CHOP) significantly improved the outcome of diffuse large B cell lymphoma (DLBCL), a common sub-type of non-Hodgkin lymphoma. But 40% – 50% of DLBCL patients cannot be cured by this regimen. Some clinical trials showed that bevacizumab might be useful in the treatment of DLBCL. This study evaluated the safety and efficacy of bevacizumab combined with the R-CHOP (A-R-CHOP) regimen in Chinese patients with previously untreated DLBCL.MethodsPatients with previously untreated DLBCL received A-R-CHOP regimen therapy. All patients with complete response (CR)/ unconfirmed complete response(CRu) after 8 cycles of A-R-CHOP received the bevacizumab maintenance therapy once every 3 weeks. The remained bulky disease was treated with radiotherapy.ResultsSeven Chinese patients were treated. All of them had bulky diseases. One patient had progressive disease after 4 cycles of A-R-CHOP therapy. The rest six patients completed 8 cycles of A-R-CHOP treatment. All of these six patients reached CR/CRu (5 CR, 1 CRu). Bevacizumab maintenance therapy was given to 4 CR patients. All 7 patients experienced Grade 3/4 hematologic adverse events; additionally, one had Grade 3 gastrointestinal toxicity and one had Grade 1 epistaxis. During bevacizumab maintenance therapy, one patient had Grade 1 gingival bleeding, another experienced Grade 1 proteinuria and then Grade 3 congestive heart failure 4 months after completion of maintenance therapy. At the end of July 2013, the patient who had progressive disease after 4 cycles of A-R-CHOP died of progressive disease, the other six remained CR response.ConclusionsThe A-R-CHOP regimen is effective for untreated DLBCL, but may cause bevacizumab-specific toxicities, which should be monitored.

The mTOR kinase inhibitor everolimus synergistically enhances the anti-tumor effect of the Bruton's tyrosine kinase (BTK) inhibitor PLS-123 on Mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive and incurable malignant disease. Despite of general chemotherapy, relapse and mortality are common, highlighting the need for the development of novel targeted drugs or combination of therapeutic regimens. Recently, several drugs that target the B‐cell receptor (BCR) signaling pathway, especially the Brutons tyrosine kinase (BTK) inhibitor ibrutinib, have demonstrated notable therapeutic effects in relapsed/refractory patients, which indicate that pharmacological inhibition of BCR pathway holds promise in MCL treatment. Here, we have developed a novel irreversible BTK inhibitor, PLS‐123, that has more potent and selective anti‐tumor activity than ibrutinib in vitro and in vivo. Using in vitro screening, we discovered that the combination of PLS‐123 and the mammalian target of rapamycin (mTOR) inhibitor everolimus exert synergistic activity in attenuating proliferation and motility of MCL cell lines. Simultaneous inhibition of BTK and mTOR resulted in marked induction of apoptosis and cell cycle arrest in the G1 phase, which were accompanied by upregulation of pro‐apoptotic proteins (cleaved Caspase‐3, cleaved PARP and Bax), repression of anti‐apoptotic proteins (Mcl‐1, Bcl‐xl and XIAP), and downregulation of regulators of the G1/S phase transition (CDK2, CDK4, CDK6 and Cyclin D1). Gene expression profile analysis revealed simultaneous treatment with these agents led to inhibition of the JAK2/STAT3, AKT/mTOR signaling pathways and SGK1 expression. Finally, the anti‐tumor and pro‐apoptotic activities of combination strategy have also been demonstrated using xenograft mice models. Taken together, simultaneous suppression of BTK and mTOR may be indicated as a potential therapeutic modality for the treatment of MCL.

Genetic polymorphisms of STAT3 correlated with prognosis in diffuse large B-cell lymphoma patients treated with rituximab

BackgroundRituximab in the combination of CHOP chemotherapy has been widely used as the standard treatment for several kinds of B-cell non-Hodgkin lymphoma (B-NHL). Inactivation of phosphorylation of STAT3 plays an essential role in rituximab-induced anti-proliferative activity in B-cell lymphoma. However, the relationship between STAT3 genetic polymorphisms and clinical response to standard frontline treatment with rituximab has not been well illustrated yet.MethodsIn this study we analyzed the STAT3 polymorphisms and prognosis of 166 diffuse large B-cell lymphoma (DLBCL) patients who were treated with rituximab from 2007 to 2010. Determination of the STAT3 polymorphisms of rs2293152 from genomic DNA was achieved by Sanger chain termination sequencing.ResultsWe did not observe obvious correlation between patients’ disease features and STAT3 polymorphisms, but patients with homozygous genotypes at rs2293162 showed a trend of higher CR rate than those with the heterozygous genotype, especially in non-GCB subgroup (p = 0.011). Furthermore, homozygous genotypes GG and CC also showed advantages of long-term survival compared with heterozygous genotype patients (p = 0.022).ConclusionsThese results suggest that STAT3 polymorphisms could be a suitable biomarker related to clinical outcome of DLBCL patients treated with rituximab.

Thiamet-G-mediated inhibition of O-GlcNAcase sensitizes human leukemia cells to microtubule-stabilizing agent paclitaxel

Although the microtubule-stabilizing agent paclitaxel has been widely used for treatment of several cancer types, particularly for the malignancies of epithelia origin, it only shows limited efficacy on hematological malignancies. Emerging roles of O-GlcNAcylation modification of proteins in various cancer types have implicated the key enzymes catalyzing this reversible modification as targets for cancer therapy. Here, we show that the highly selective O-GlcNAcase (OGA) inhibitor thiamet-G significantly sensitized human leukemia cell lines to paclitaxel, with an approximate 10-fold leftward shift of IC50. Knockdown of OGA by siRNAs or inhibition of OGA by thiamet-G did not influence the cell viability. Furthermore, we demonstrated that thiamet-G binds to OGA in competition with 4-methylumbelliferyl N-acetyl-β-d-glucosaminide dehydrate, an analogue of O-GlcNAc UDP, thereby suppressing the activity of OGA. Importantly, inhibition of OGA by thiamet-G decreased the phosphorylation of microtubule-associated protein Tau and caused alterations of microtubule network in cells. It is noteworthy that paclitaxel combined with thiamet-G resulted in more profound perturbations on microtubule stability than did either one alone, which may implicate the underlying mechanism of thiamet-G-mediated sensitization of leukemia cells to paclitaxel. These findings thus suggest that a regimen of paclitaxel combined with OGA inhibitor might be more effective for the treatment of human leukemia.

CLINICAL FEATURES AND PROGNOSES OF PRIMARY GASTRIC DIFFUSE LARGE B CELL LYMPHOMA: A RETROSPECTIVE ANALYSIS OF 139 CHINESE CASES WITH IMMUNOPHENOTYPING FROM CLAP

TREATMENT STRATEGIES AND PROGNOSTIC FACTORS OF PRIMARY GASTRIC DIFFUSE LARGE B CELL LYMPHOMA: A RETROSPECTIVE STUDY OF 303 CASES FROM CHINA LYMPHOMA PATIENT REGISTRY Y. Song* | X. Cen | H. Yang | M. Wu | Y. Shen | T. Lei | X. Leng | L. Ping | Y. Xie | J. Zhu Department of Lymphoma, Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital & Institute, Beijing, China; Department of Hematology, Peking University First Hospital, Beijing, China; Department of Lymphoma, Zhejiang Cancer Hospital, Hangzhou, China

TREATMENT STRATEGIES AND PROGNOSTIC FACTORS OF PRIMARY GASTRIC DIFFUSE LARGE B CELL LYMPHOMA: A RETROSPECTIVE STUDY OF 303 CASES FROM CHINA LYMPHOMA PATIENT REGISTRY

TREATMENT STRATEGIES AND PROGNOSTIC FACTORS OF PRIMARY GASTRIC DIFFUSE LARGE B CELL LYMPHOMA: A RETROSPECTIVE STUDY OF 303 CASES FROM CHINA LYMPHOMA PATIENT REGISTRY Y. Song* | X. Cen | H. Yang | M. Wu | Y. Shen | T. Lei | X. Leng | L. Ping | Y. Xie | J. Zhu Department of Lymphoma, Key laboratory of Carcinogenesis and Translational Research (Ministry of Education), Peking University Cancer Hospital & Institute, Beijing, China; Department of Hematology, Peking University First Hospital, Beijing, China; Department of Lymphoma, Zhejiang Cancer Hospital, Hangzhou, China

THE BRUTON'S TYROSINE KINASE INHIBITOR IBRUTINIB EXERTS IMMUNOMODULATORY ACTIVITY TOWARDS TUMOR-INFILTRATING MACROPHAGES

Introduction:Metformin exerts anti‐tumor effects in part by activating AMP‐activated protein kinase (AMPK) with resultant reduction in pro‐ survival mTOR signaling. Here, we test the hypothesis that metformin induces cell death by altering mitochondrial metabolism in lymphoma cell lines. As Bcl‐2 proteins, cyclin‐dependent kinases (CDK) and Phosphoinositol‐3‐kinase (PI3K) also influence mitochondrial physiology and metabolism, we also explored the additive effects of metformin with novel agents including the Bcl‐2 inhibitor (ABT‐199), the CDK9 inhibitor (BAY‐1143572) and the p110δ‐selective PI3K inhibitor (CAL‐101). Methods: Daudi (Burkitt), SUDHL‐4 (GC DLBCL), Jeko‐1 (MCL) and KPUM‐UH1 (double hit DLBCL) cells were plated in 96‐well plates and treated with varying doses of metformin (0–5000 μM). Hoechst 33342 DNA‐binding dye or MTS assays were used to measure proliferation and cell viability, respectively. Perturbations in oxidative and glycolytic metabolism were monitored via Seahorse XF Energy Phenotype kits. Lastly, efficacy of combination therapy was evaluated in cells co‐treated with metformin and ABT‐199 or BAY‐ 1143572 or CAL‐101. Results: Daudi and SUDHL‐4 cells showed 80% and 50% reduction in viability, respectively, with metformin at levels greater than 1 mM at day 7, while KPUM‐UH1 and Jeko‐1 cells were unaffected. The Seahorse analyses showed reduction in oxidative phosphorylation, in cells treated with 1mM metformin with a corresponding increase in glycolysis. Co‐treating KPUM‐UH1 and SUDHL‐4 cells with 10 mM metformin resulted in 1.4‐fold and 8.8‐fold decreases, respectively, in IC50 values of ABT‐199 at day 3 (Table 1). Jeko‐1 and Daudi cells were resistant to ABT‐199. By contrast, 3‐fold and 10 fold reduction in IC50 values of BAY‐1143572 in Daudi and Jeko‐1, respectively, was seen in the presence of 10 mM Metformin, and SUDHL‐4 or KPUM‐UH1 cells were unaffected. No change in IC50 value for CAL‐ 101 was observed. Conclusions: Metformin induces significant changes in cellular metabolism leading to decreased proliferation and viability in lymphoma cell lines. The combination of metformin and the anti‐ Bcl‐2 agent ABT‐199 achieves an additive effect in DLBCL (including double hit) cell lines, whereas the combination with CDK9 inhibitor BAY‐1143572 provides more selective additive anti‐tumor effect in Burkitt and MCL cell lines. These data support the idea of targeting cancer metabolism with metformin in novel combinatorial therapeutic strategies.

TP53 Arg72 as a favorable prognostic factor for Chinese diffuse large B-cell lymphoma patients treated with CHOP

BackgroundTP53 Arg72Pro (SNP rs1042522) is associated with risk of non-Hodgkin lymphoma (NHL). Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of NHL. However, the relationship between this SNP and prognosis of DLBCL in Asians is unknown.MethodsGenotyping of TP53 Arg72Pro was done in 425 Chinese DLBCL patients. Two hundred and eighty-nine patients were treated with R-CHOP, and 136 patients received CHOP or CHOP-like as frontline regimen. Three hundred and ninety-six patients were assessable for the efficacy.ResultsPatients with Arg/Arg and Arg/Pro at codon 72 of TP53 had a higher complete response rate (61% vs. 44%, P = 0.007) than those with Pro/Pro. In the subgroup treated with CHOP or CHOP-like therapy, patients with Arg/Arg and Arg/Pro showed a higher 5-year overall survival (OS) rate than those with Pro/Pro (68.8% vs. 23.2%, P = 0.001). Multivariate Cox regression analysis revealed TP53 Arg72 as a favorable prognostic factor in this group. However, the combination of rituximab with CHOP significantly increased the 5-year OS rate of patients with Pro/Pro to 63%.ConclusionThis study revealed TP53 Arg72 as a favorable prognostic factor for Chinese DLBCL patients treated with CHOP or CHOP-like as frontline therapy.