Yunhua He

Pyruvate kinase isoform M2 (PKM2) participates in multiple myeloma cell proliferation, adhesion and chemoresistance

Cell adhesion mediated drug resistance (CAM-DR) remains the major barrier in human multiple myeloma (MM) therapy. In the present study, we aimed at investigating the role of pyruvate kinase isoform M2 (PKM2) in MM CAM-DR. We determined that PKM2 expression was positively correlated with cell proliferation and knockdown of PKM2 contributed to the increased cell adhesion rate in MM. The enhancement in the adhesion of MM cells to fibronectin or the bone marrow stroma cell line HS-5 cells translated to an increased CAM-DR phenotype. Importantly, we showed that this CAM-DR phenotype was correlated with the phosphorylation of Akt and ERK in MM cells. Taken together, our data shed new light on the molecular mechanism of CAM-DR in MM, and targeting PKM2 may be a novel therapeutic approach for improving the effectiveness of chemotherapy in MM.

Cell adhesion induces overexpression of chromodomain helicase/ATPase DNA binding protein 1-like gene (CHD1L) and contributes to cell adhesion-mediated drug resistance (CAM-DR) in multiple myeloma cells

Previous studies have shown that chromodomain helicase/ATPase DNA binding protein 1-like gene (CHD1L) exerts its anti-apoptotic function in many solid cancers. However, its role in human multiple myeloma (MM) has not been thoroughly elucidated. In this study, we investigate the role of CHD1L in MM. Preliminarily, up-regulation and down-regulation assay verified that CHD1L exerts its anti-apoptotic role through the apoptotic pathway involving caspase-9-caspase-3 apoptotic pathway in MM cells. In addition, we determined that CHD1L expression is increased when MM cells were adhered to fibronectin (FN) or bone marrow stromal cell line HS-5 cells and cell adhesion assay indicated that CHD1L siRNA reversed the high cell adhesion rate. Consistent with the reduced adhesion rate, the cells translated to a compromised cell adhesion-mediated drug resistance (CAM-DR) phenotype in MM. In summary, we will propose strategies for developing a CHD1L inhibitor for potential treatment of MM.

Silencing of DYRK2 increases cell proliferation but reverses CAM-DR in Non-Hodgkin's Lymphoma

DYRK2, a dual-specificity tyrosine-(Y)-phosphorylation regulated kinase gene, is involved in regulating many processes such as cell proliferation, cell differentiation and cytokinesis. DYRK2 also plays an important role in many cancers, such as breast cancer, non-small cell lung cancer and esophageal adenocarcinomas. In this study, we found that DYRK2 is associated with the proliferation of Non-Hodgkins lymphoma (NHL) and cell adhesion mediated drug resistance (CAM-DR). Clinically, the mRNA and protein expression levels of DYRK2 are decreased in NHL tissues compared with reactive lymphoid hyperplasia tissues. Immunohistochemical analysis revealed that low expression of DYRK2 is associated with poor prognosis of NHL patients. Interestingly, knockdown of DYRK2 can promote cell proliferation via modulating cell cycle progression. Finally, we demonstrated that DYRK2 plays an important role in CAM-DR by regulating p27(Kip1) expression. Importantly, DYRK2 knockdown reverses CAM-DR in NHL. Our research suggested that DYRK2 may be a novel therapeutic target for NHL.

Y-box-binding protein-1 (YB-1) promotes cell proliferation, adhesion and drug resistance in diffuse large B-cell lymphoma

YB-1 is a multifunctional protein, which has been shown to correlate with resistance to treatment of various tumor types. This study investigated the expression and biologic function of YB-1 in diffuse large B-cell lymphoma (DLBCL). Immunohistochemical analysis showed that the expression statuses of YB-1 and pYB-1(S102) were reversely correlated with the clinical outcomes of DLBCL patients. In addition, we found that YB-1 could promote the proliferation of DLBCL cells by accelerating the G1/S transition. Ectopic expression of YB-1 could markedly increase the expression of cell cycle regulators cyclin D1 and cyclin E. Furthermore, we found that adhesion of DLBCL cells to fibronectin (FN) could increase YB-1 phosphorylation at Ser102 and pYB-1(S102) nuclear translocation. In addition, overexpression of YB-1 could increase the adhesion of DLBCL cells to FN. Intriguingly, we found that YB-1 overexpression could confer drug resistance through cell-adhesion dependent and independent mechanisms in DLBCL. Silencing of YB-1 could sensitize DLBCL cells to mitoxantrone and overcome cell adhesion-mediated drug resistance (CAM-DR) phenotype in an AKT-dependent manner.

Sam68 regulates cell proliferation and cell adhesion‐mediated drug resistance (CAM‐DR) via the AKT pathway in non‐Hodgkin's lymphoma

Sam68 (Src‐associated in mitosis 68 kDa), a substrate for tyrosine kinase c‐Src during mitosis, is up‐regulated in a variety of human cancers and acts oncogenically promoting tumour progression. This study has explored biological function and clinical significance of Sam68 in non‐Hodgkins lymphoma (NHL).

ADP-ribosylation factor 1 (ARF1) takes part in cell proliferation and cell adhesion-mediated drug resistance (CAM-DR)

Cell adhesion-mediated drug resistance (CAM-DR) remains the primary obstacle in human multiple myeloma (MM) therapy. In this study, we aimed at investigating the expression and biologic function of ARF1 in MM. We determined that ARF1 expression was positively correlated with cell proliferation and knockdown of ARF1 contributed to CAM-DR. The enhancement in the adhesion of MM cells to fibronectin (FN) or the bone marrow stroma cell line HS-5 cells translated to an increased CAM-DR phenotype. Importantly, we showed that this CAM-DR phenotype was correlated with the phosphorylation of Akt and ERK in MM cells. Moreover, we sought to determine whether ARF1 could interact with p27 in RPMI8226 cells. Knockdown of ARF1 also significantly decreased pT157-p27 protein expression in RPMI8226 cells. Our research shows ARF1 may reverse CAM-DR by regulating phosphorylation of p27 at T157 in MM. Taken together, our data shed new light on the molecular mechanism of CAM-DR in MM, and targeting ARF1 may be a novel therapeutic approach for improving the effectiveness of chemotherapy in MM.

Cell adhesion down-regulates the expression of vacuolar protein sorting 4B (VPS4B) and contributes to drug resistance in multiple myeloma cells

The expression and biologic function of the gene encoding vacuolar protein sorting 4B (VPS4B) in human multiple myeloma (MM) were investigated in this study. We determined that VPS4B expression is decreased in adherent MM cells and that knockdown of VPS4B expression induces cell adhesion-mediated drug resistance (CAM-DR) in MM. This induced CAM-DR phenotype manifested through down-regulation of cell apoptosis and requires phosphorylation of AKT and Erk. Finally, VPS4B expression was positively correlated with cell proliferation. Our findings support a role for VPS4B in MM cell proliferation, adhesion, and drug resistance, and pave the way for a novel therapeutic approach targeting this molecule.

Cell adhesion downregulates the expression of Homer1b/c and contributes to drug resistance in multiple myeloma cells

Previous studies have demonstrated that Homer1b/c plays an important pro-apoptotic role through classical mitochondrial apoptotic pathway. The present study was undertaken to determine the expression and functional significance of Homer1b/c in multiple myeloma (MM). We found that Homer1b/c was lowly expressed in MM cell apoptotic model induced by doxorubicin. The positive role of Homer1b/c in cell apoptosis was further confirmed by knocking down Homer1b/c. Further study confirmed that Homer1b/c was able to affect the CAM-DR via pro-apoptotic activity regulating the ability of cell adhesion. Collectively, these data indicate that Homer1b/c may represent a good candidate for pursuing clinical trial in MM.

Expression of vaccinia-related kinase 1 (VRK1) accelerates cell proliferation but overcomes cell adhesion mediated drug resistance (CAM-DR) in multiple myeloma.

Objective: Vaccinia-related kinase 1 (VRK1) has been reported to participate in the development of a variety of tumors. However, the role of VRK1 in multiple myeloma (MM) has not been investigated. The present study was undertaken to determine the expression and biologic function of VRK1 in human MM. Methods: First, we constructed a model of cell adhesion in MM, the mRNA and protein level of VRK1 in suspension and adhesion model was analyzed by RT-PCR and western blot. Then, flow cytometry assay and western blot were used to investigate the mechanism of VRK1 in the proliferation of MM cells. In vitro, following using shRNA interfering VRK1 expression, we performed adhesion assay and cell viability assay to determine the effect of VRK1 on adhesive rate and drug sensitivity. Results: VRK1 was lowly expressed in adherent MM cells and highly expressed in suspended cells. In addition, VRK1 was positively correlated with the proliferation of MM cells by regulating the expression of cell cycle-related protein, such as cyclinD1, CDK2 and p27kip1. Furthermore, VRK1 could reverse cell adhesion mediated drug resistance (CAM-DR) by down-regulating the ability of cell adhesion. Conclusion and discussion: Our data supports a role for VRK1 in MM cell proliferation, adhesion, and drug resistance, and it may pave the way for a novel therapeutic approach for CAM-DR in MM.