CIAPIN1 targets Na/H exchanger 1 to mediate K562 chronic myeloid leukemia cells’ differentiation via ERK1/2 signaling pathway

CIAPIN1 (cytokine-induced antiapoptotic inhibitor 1) was recently identified as an essential downstream effector of the Ras signaling pathway. However, its potential role in regulating myeloid differentiation remains unclear. In this study, we found depletion of CIAPIN1 by shRNAs led to granulocytic differentiation of K562 cells. Meanwhile, the decrease of NHE1 and up-regulation of phosphorylated ERK1/2 were observed after CIAPIN1 depletion. Interestingly, targeted inhibition of NHE1 further promoted the differentiation of K562 cells with CIAPIN1 silencing. Accordingly, ectopic expression of NHE1 reversed this phenotype. Furthermore, ERK1/2 inhibition with the chemical inhibitor, PD98059, abolished CIAPIN1 silencing-induced differentiation of K562 cells after NHE1 inhibition. Thus, our results revealed important mechanism that CIAPIN1 targeted NHE1 to mediate differentiation of K562 cells via ERK1/2 pathway. Our findings implied CIAPIN1 and NHE1 could be new targets in developing therapeutic strategies against leukemia.     

Hydrogen ion dynamics and the Na+/H+ exchanger in cancer angiogenesis and antiangiogenesis

Tumour angiogenesis and cellular pH regulation, mainly represented by Na(+)/H(+) antiporter exchange, have been heretofore considered unrelated subfields of cancer research. In this short review, the available experimental evidence relating these areas of modern cancer research is introduced. This perspective also helps to design a new approach that facilitates the opening and development of novel research lines oriented towards a rational incorporation of anticancer drugs into more selective and less toxic therapeutic protocols. The final aim of these efforts is to control cancer progression and dissemination through the control of tumour angiogenesis. Finally, different antiangiogenic drugs that can already be clinically used to this effect are briefly presented.     

Reversal of Imatinib resistance in BCR-ABL-positive leukemia after inhibition of the Na+/H+ exchanger

The present study was undertaken to estimate the therapeutic benefit to down-regulate the Na(+)/H(+) exchanger 1 (NHE1) for reversing chemoresistance of BCR-ABL-positive leukemia patient cells and cell lines. As a result, after treatment with specific NHE1 inhibitor Cariporide or high K(+) buffer to decrease intracellular pH (pH(i)), cells from relapsed patients exhibited decreased Pgp level, enhanced Rhodamine123 and drug accumulation, decreased colony-forming ability and the modulations of mitogen-activated protein kinases (MAPKs) activities. Furthermore, we used BCR-ABL-positive cell line K562 and its resistant counterparts K562/DOX and K562/G01 cell lines for further study. Together, these findings suggest that Pgp may be associated with the reversal of drug resistance in BCR-ABL-positive leukemia patients and cell lines by the inhibition of NHE1 though MAPK pathways.     

CD44+/CD24-细胞在乳腺癌组织中比例与乳腺癌远处转移关系

目的:旨在探讨CD44+/CD 24-细胞在乳腺癌组织中的比例与乳腺癌远处转移之间关系。方法:随机选取2003年1 月至2004年10月于天津医科大学肿瘤医院确诊的乳腺癌患者60例,并将其分为30例转移组及30例非转移组（对照组）。 免疫组织化学双重染色技术检测60例患者石蜡切片中CD44+/CD 24-细胞在乳腺癌组织中所占比例,分析其与远处转移之间关系。结果:转移组与对照组中CD44+/CD 24-细胞在乳腺癌组织中所占比例具有显著性差异（χ2= 11.334 ,P < 0.05）。 骨转移中CD44+/CD24-细胞在乳腺癌组织中比例有显著性差异（χ2= 9.250 ,P = 0.01）。 CD44+/CD 24-细胞在乳腺癌组织中5 年无瘤生存期比例有显著性差异（χ2= 8.058,P = 0.005）。结论:CD44+/CD 24-细胞在乳腺癌组织中所占比例与乳腺癌远处转移密切相关,特别是骨转移。      

A switch from CD44+ cell to EMT cell drives the metastasis of prostate cancer

Epithelial–mesenchymal transition (EMT) has been linked to cancer stem-like (CD44+) cell in the prostate cancer (PCa) metastasis. However, the molecular mechanism remains elusive. Here, we found EMT contributed to metastasis in PCa patients failed in androgen deprivation therapy (ADT). Castration TRAMP model also proved PCa treated with ADT promoted EMT with increased CD44+ stem-like cells. Switched CD44+ cell to EMT cell is a key step for luminal PCa cell metastasis. Our results also suggested ADT might go through promoting TGFβ1-CD44 signaling to enhance swift to EMT. Targeting CD44 with salinomycin and siRNA could inhibit cell transition and decrease PCa invasion. Together, cancer stem-like (CD44+) cells could be the initiator cells of EMT modulated by TGFβ1-CD44 signaling. Combined therapy of ADT with anti-CD44 may become a new potential therapeutic approach to battle later stage PCa.     

Inhibition of Na/H exchanger 1 by 5-(N-ethyl-N-isopropyl) amiloride reduces hypoxia-induced hepatocellular carcinoma invasion and motility

Na⁺/H⁺ exchanger 1 (NHE1) plays a significant role in tumor metastasis. However, the exact mechanisms by which NHE1 mediates cell invasion and migration, especially in hepatocellular carcinoma (HCC), are not yet known. In the current study, we show for the first time that the inhibition of NHE1 by 5-(N-ethyl-N-isopropyl) amiloride (EIPA) is able to suppress migration and invasion of HepG2 cells under hypoxic conditions. In addition, hypoxia activated ERK1/2, which in turn promoted the production of MMP-2, MMP-9 and VEGF. EIPA’s suppressive role was determined to act through down-regulation of MMP-2, MMP-9 and VEGF in an ERK1/2 dependent manner. The data demonstrate that NHE1 plays a role in HCC invasion and that NHE1 may be a potential therapeutic target for HCC treatment.     

PD-1+ CD8+ T cells are exhausted in tumours and functional in draining lymph nodes of colorectal cancer patients

Background:

The blockade of PD-1–PD-L1 pathway is emerging as an effective therapeutic strategy for several advanced cancers. But the immune regulatory role of PD-1–PD-L1 pathway is not clear in colorectal cancer (CRC) patients. This study aims to evaluate the role of PD-1–PD-L1 pathway in CD8⁺ T-cell functions in tumour-draining lymph nodes (TDLNs) and tumours of CRC patients.

Methods:

PD-1 expression on CD8⁺ T cells was examined by flow cytometry, and PD-L1 expression in TDLNs and tumour tissues were examined by immunohistochemistry. Production of IFN-γ, IL-2 and expression of granzyme B, perforin in CD8⁺ T cells were detected by intracellular staining.

Results:

PD-1 expression is markedly upregulated on CD8⁺ T cells in TDLNs and tumours compared with that in peripheral blood. PD-1-expressing CD8⁺ T cells are competent for production of cytokine (IL-2 and IFN-γ) and perforin in the tumour-free lymph nodes (TFLNs), but exhibit exhausted phenotypes in tumours. In addition, PD-L1 is highly expressed in tumours rather than TFLNs, which is closely correlated with the impairment of IFN-γ production of tumour-infiltrating PD-1⁺ CD8⁺ T cells.

Conclusions:

Our findings suggest a suppressive effect of PD-1 on CD8⁺ T-cell function in tumours, but not in TFLNs.     

Inhibition of K562 leukemia angiogenesis and growth by selective Na+/H+ exchanger inhibitor cariporide through down-regulation of pro-angiogenesis factor VEGF

To investigate the effect of inhibition of Na⁺/H⁺ exchanger isoform1 (NHE1) on K562 leukemia-driven angiogenesis, the selective NHE1 inhibitor cariporide was used. Cariporide treatment of K562 resulted in a decrease in pHi and down-regulation of VEGF secretion. The proliferation, migration and in vitro tube formation of human umbilical vein endothelial cells was decreased in cariporide treated K562 condition medium (CM) while VEGF supplement could partially restore the inhibitory effect. Subcutaneous injection of nude mice with cariporide inhibited K562 tumor growth with a reduction of the density of microvessels compared to the control group.     

Na+-induced Ca2+ influx through reverse mode of Na+-Ca2+ exchanger in mouse ventricular cardiomyocyte

Background

Dobutamine is commonly used for clinical management of heart failure and its pharmacological effects have long been investigated as inotropics via β–receptor activation. However, there is no electrophysiological evidence if dobutamine contributes inotropic action due at least partially to the reverse mode of Na⁺-Ca²⁺ exchanger (NCX) activation.

Methods

Action potential (AP), voltage-gated Na⁺ (I_Na), Ca²⁺ (I_Ca), and K⁺ (I_to and I_K1) currents were observed using whole-cell patch technique before and after dobutamine in ventricular cardiomyocytes isolated from adult mouse hearts. Another sets of observation were also performed with Kb-r7943 or in the solution without [Ca²⁺]_o.

Results

Dobutamine (0.1–1.0 μM) significantly enhanced the AP depolarization with prolongation of AP duration (APD) in a concentration-dependent fashion. The density of I_Nawas also increased concentration-dependently without alternation of voltage-dependent steady-status of activation and inactivation, reactivation as well. Whereas, the activities for I_Ca, I_to, and I_K1 were not changed by dobutamine. Intriguingly, the dobutamine-mediated changes in AP repolarization were abolished by 3 μM Kb-r7943 pretreatment or by simply removing [Ca²⁺]_o without affecting accelerated depolarization. Additionally, the ratio of APD₅₀/APD₉₀ was not significantly altered in the presence of dobutamine, implying that effective refractory period was remain unchanged.

Conclusion

This novel finding provides evidence that dobutamine upregulates of voltage-gated Na⁺ channel function and Na⁺ influx-induced activation of the reverse mode of NCX, suggesting that dobutamine may not only accelerate ventricular contraction via fast depolarization but also cause Ca²⁺ influx, which contributes its positive inotropic effect synergistically with β-receptor activation without increasing the arrhythmogenetic risk.     

Enriched CD44/CD24 population drives the aggressive phenotypes presented in triple-negative breast cancer (TNBC)

The mechanism underlying the aggressive behaviors of triple negative breast cancer (TNBC) is not well characterized yet. The association between cancer stem cell (CSC) population and the aggressive behaviors of TNBC has not been established. We found the CD44⁺/CD24⁻ cell population was enriched in TNBC tissues and cell lines, with a higher capacity of proliferation, migration, invasion and tumorigenicity as well as lower adhesion ability. The CD44⁺/CD24⁻ cell population with cancer stem cell-like properties may play an important role in the aggressive behaviors of TNBC. This discovery may lead to new therapeutic strategies targeting CD44⁺/CD24⁻ cell population in TNBC.     

Mitochondrial malic enzyme 2 promotes breast cancer metastasis via stabilizing HIF-1α under hypoxia

Objectiveα-ketoglutarate (α-KG) is the substrate to hydroxylate collagen and hypoxia-inducible factor-1α (HIF-1α), which are important for cancer metastasis. Previous studies have shown that the upregulation of collagen prolyl 4-hydroxylase in breast cancer cells stabilizes the expression of HIF-1α by depleting α-KG levels. We hypothesized that mitochondrial malic enzyme 2 (ME2) might also affect HIF-1α expression via modulating α-KG levels in breast cancer cells.MethodsWe evaluated ME2 protein expression in 100 breast cancer patients using immunohistochemistry and correlated with clinicopathological indicators. The effect of ME2 knockout on cancer metastasis was evaluated using an orthotopic breast cancer model. The effect of ME2 knockout or knockdown on the levels of α-KG and HIF-1α proteins in breast cancer cell lines was determined both in vitro and in vivo. ResultsME2 was found to be upregulated in the human breast cancerous tissues compared with the matched precancerous tissues (P<0.001). The elevated expression of ME2 was associated with a poor prognosis (P=0.019). ME2 upregulation was also related to lymph node metastasis (P=0.016), pathological staging (P=0.033), and vascular cancer embolus (P=0.014). Also, ME2 knockout significantly inhibited lung metastasisin vivo. In the tumors formed by ME2 knockout cells, the levels of α-KG were significantly increased and collagen hydroxylation level did not change significantly but HIF-1α protein expression was significantly decreased, compared to the control samples. In cell culture, cells with ME2 knockout or knockdown demonstrated significantly higher α-KG levels but significantly lower HIF-1α protein expression than control cells under hypoxia. Exogenous malate and α-KG exerted similar effect on HIF-1α in breast cancer cells to ME2 knockout or knockdown. Additionally, treatment with malate significantly decreased 4T1 breast cancer lung metastasis. ME2 expression was associated with HIF-1α levels in human breast cancer samples (P=0.008). ConclusionsOur results provide evidence that upregulation of ME2 is associated with a poor prognosis of breast cancer patients and propose a mechanistic understanding of a link between ME2 and breast cancer metastasis.     

Transforming growth factor‐β induces CD44 cleavage that promotes migration of MDA‐MB‐435s cells through the up‐regulation of membrane type 1‐matrix metalloproteinase

CD44, a transmembrane receptor for hyaluronic acid, is implicated in various adhesion‐dependent cellular processes, including cell migration, tumor cell metastasis and invasion. Recent studies demonstrated that CD44 expressed in cancer cells can be proteolytically cleaved at the ectodomain by membrane type 1‐matrix metalloproteinase (MT1‐MMP) to form soluble CD44 and that CD44 cleavage plays a critical role in cancer cell migration. Here, we show that transforming growth factor‐β (TGF‐β), a multifunctional cytokine involved in cell proliferation, differentiation, migration and pathological processes, induces MT1‐MMP expression in MDA‐MB‐435s cells. TGF‐β‐induced MT1‐MMP expression was blocked by the specific extracellular regulated kinase‐1/2 (ERK1/2) inhibitor PD98059 and the specific phosphoinositide 3‐OH kinase (PI3K) inhibitor LY294002. In addition, treatment with SP600125, an inhibitor for c‐Jun NH₂‐terminal kinase (JNK), resulted in a significant inhibition of MT1‐MMP production. These data suggest that ERK1/2, PI3K, and JNK likely play a role in TGF‐β‐induced MT1‐MMP expression. Interestingly, treatment of MDA‐MB‐435s cells with TGF‐β resulted in a colocalization of MT1‐MMP and CD44 in the cell membrane and in an increased level of soluble CD44. Using an electric cell‐substrate impedance sensing cell‐electrode system, we demonstrated that TGF‐β treatment promotes MDA‐MB‐435s cell migration, involving MT1‐MMP‐mediated CD44 cleavage. MT1‐MMP siRNA transfection‐inhibited TGF‐β‐induced cancer cell transendothelial migration. Thus, this study contributes to our understanding of molecular mechanisms that play a critical role in tumor cell invasion and metastasis. © 2009 Wiley‐Liss, Inc.     

Cytostatic potential of novel agents that inhibit the regulation of intracellular pH

Cells within the acidic extracellular environment of solid tumours maintain their intracellular pH (pHi) through the activity of membrane-based ion exchange mechanisms including the Na(+)/H(+) antiport and the Na(+)-dependent Cl(-)/HCO(3)(-) exchanger. Inhibition of these regulatory mechanisms has been proposed as an approach to tumour therapy. Previously available inhibitors of these exchangers were toxic (e.g. 4,4-diisothiocyanstilbene-2,2-disulphonic acid), and/or non-specific (e.g. 5-N-ethyl-N-isopropyl amiloride). Using two human (MCF7, MDA-MB231) and one murine (EMT6) breast cancer cell lines, we evaluated the influence of two new agents, cariporide (an inhibitor of the Na(+)/H(+) antiport) and S3705 (an inhibitor of the Na(+)-dependent Cl(-)/HCO(3)(-) exchanger) on the regulation of intracellular pH (pHi). The cytotoxicity of the two agents was assessed by using clonogenic assays. Our results suggest that cariporide has similar efficacy and potency to 5-N-ethyl-N-isopropyl amiloride for inhibition of Na(+)/H(+) exchange while S3705 is more potent and efficient than 4,4-diisothiocyanstilbene-2,2-disulphonic acid in inhibiting Na+-dependent Cl(-)/HCO3(-) exchange. The agents inhibited the growth of tumour cells when they were incubated at low pHe (7.0-6.8), but were non-toxic to cells grown at doses that inhibited the regulation of pHi. Our results indicate that cariporide and S3705 are selective cytostatic agents under in vitro conditions that reflect the slightly acidic microenvironment found in solid tumours.     

Prediction of metastasis risk (11 year follow-up) using VEGF-R1, VEGF-R2, Tie-2/Tek and CD105 expression in breast cancer (n=905)

Neoangiogenesis in tumours contributes to the development of blood-borne metastases, and can be evaluated by markers of activated endothelial cells in preference to panendothelial markers. Our purpose was to document the prognostic significance of VEGF-R1, VEGF-R2, Tie-2/Tek and CD105 immunoexpression in breast carcinoma frozen samples (n=905, follow-up=11.7 years). We observed that: (i). CD105 (P=0.001) and Tie-2/Tek (P=0.025) (but not VEGF-R1 and VEGF-R2) overexpression correlated with a shorter survival, and were (Cox's model) independent histoprognostic indicators; (ii). only CD105 marked expression correlated (P=0.035) with a shorter survival of node-negative patients; (iii). three markers - CD105 (P=0.001), Tie-2/Tek (P=0.01), VEGF-R1 (P=0.001), but not VEGF-R2 - correlated with metastatic risk in node-negative patients in univariate analysis; and (iv). VEGF-R1 (P=0.01) expression correlated with high local recurrence risk. It is concluded that CD105 and to a lesser extent Tie-2/Tek and VEGF-R1, but not VEGF-R2 are endowed with prognostic significance that may be useful for patient monitoring, particularly CD105 expression for selecting node-negative patients for more aggressive postsurgery therapy.     

Anti-4-1BB antibody-based combination therapy augments antitumor immunity by enhancing CD11c+CD8+ T cells in renal cell carcinoma

To improve the potential treatment strategies of incurable renal cell carcinoma (RCC), which is highly resistant to chemotherapy and radiotherapy, the present study established a combination therapy with immunostimulatory factor (ISTF) and anti-4-1BB monoclonal antibodies (mAbs) to augment the antitumor response in a murine RCC model. ISTF isolated from Actinobacillus actinomycetemcomitans stimulates macrophages, dendritic cells and B cells to produce IL-6, TNF-α, nitric oxide and major histocompatibility complex class II expression. 4-1BB (CD137) is expressed in activated immune cells, including activated T cells, and is a promising target for cancer immunotherapy. The administration of anti-4-1BB mAbs promoted antitumor immunity via enhancing CD11c⁺CD8⁺ T cells. The CD11c⁺CD8⁺ T cells were characterized by high killing activity and IFN-γ-producing ability, representing a phenotype of active effector cytotoxic T lymphocytes. The present study showed that combination therapy with ISTF and anti-4-1BB mAbs promoted partial tumor regression with established RCC, but monotherapy with ISTF or anti-4-1BB mAbs did not. These effects were speculated to be caused by the increase in CD11c⁺CD8⁺ T cells in the spleen and tumor, and IFN-γ production. These insights into the effector mechanisms of the combination of ISTF and anti-4-1BB mAbs may be useful for targeting incurable RCC.     

Expansion of CD3+CD8+PD1+ T lymphocytes and TCR repertoire diversity predict clinical responses to adoptive cell therapy in advanced gastric cancer

The adoptive cell therapy (ACT) and delivery of ex vivo activated cellular products, such as dendritic cells (DCs), NK cells, and T cells, have shown promise for the treatment of gastric cancer (GC). However, it is unknown which cells can improve patient survival. This study was focused on the antitumour activity of a subset of these cellular products and their relationships with clinical outcomes. Nineteen patients were enrolled at the Capital Medical University Cancer Center, Beijing Shijitan Hospital, from June 1, 2013, to May 30, 2016. CD8⁺PD1⁺ T-cell sorting was carried out using flow cytometry, and the T-cell receptor (TCR) repertoire during ex vivo expansion for 15 days was analyzed by next-generation sequencing. After 15 days of culture, the number of CD8⁺ T cells had increased significantly, and the number of CD4⁺ T cells had increased correspondingly. After ex vivo expansion, CD8⁺ T cells exhibited significantly enhanced expression of PD-1, LAG-3, and TIM-3 but not 4-1BB. Survival analysis showed that patients with a pro/pre value of CD8⁺PD-1⁺ T cells >2.4 had significantly favorable overall survival (OS) (median OS time, 248 days versus 96 days, P=0.02) and progression-free survival (PFS) (median PFS time, 183 days vs. 77 days, P=0.002). The sorted CD8⁺PD-1⁺ T cells displayed enhanced antitumor activity and increased IFN-γ secretion after coculture with autologous tumor cell lines. TCR repertoire diversity was decreased after ex vivo expansion, which decreased the Shannon index and increased the clonality value. The prognosis of patients was significantly improved and was associated with the extent of CD8⁺PD-1⁺ T-cell expansion. In summary, this study showed that after ex vivo expansion for 15 days, CD8⁺PD-1⁺ T cells could be identified as tumor-reactive cells in patients treated for GC. Changing TCR species can predict the extent of CD3⁺CD8⁺PD1⁺ T-cell growth and the effect of ACT treatment.     

Tunicamycin inhibits cell proliferation and migration in hepatocellular carcinoma through suppression of CD44s and the ERK1/2 pathway

Tunicamycin (TM) is an N‐linked glycosylation (NLG) inhibitor with strong antitumor activity, the exact underlying molecular mechanism of which remains to be elucidated. In our previous studies, we found that TM reversed drug resistance and improved the efficacy of combination treatments for hepatocellular carcinomas (HCC). Here, we investigated the effects of TM on HCC cell proliferation and migration as well as the mechanism of those effects. Our results showed that TM inhibited cell proliferation and migration as well as induced apoptosis of hepatocellular carcinoma cells. TM inhibited proliferation of HCC cells by inducing cell apoptosis and cell cycle arrest at the G2/M phase. Meanwhile, TM inhibited migration of HCC cells by suppressing CD44s‐mediated epithelial‐mesenchymal transition (EMT). TM inhibited migration and invasion of HCC cells by decreasing CD44 expression and altering its glycosylation. In addition, CD44s is involved in promoting EMT and is associated with a poor prognosis in HCC patients. Overexpression of CD44s promoted tumor migration and activated phosphorylation of ERK1/2 in HCC cells, whereas TM inhibited CD44s overexpression‐associated cell migration. The ability of TM to inhibit cell migration and invasion was enhanced or reversed in CD44s knockdown cells and cells overexpressing CD44s, respectively. The MEK/ERK inhibitor U0126 and TM inhibited hyaluronic acid‐induced cell migration in HCC cells. Furthermore, TM inhibited exogenous transforming growth factor beta (TGF‐β)‐mediated EMT by an ERK1/2‐dependent mechanism and restored the TGF‐β‐mediated loss of E‐cadherin. In summary, our study provides evidence that TM inhibits proliferation and migration of HCC cells through inhibition of CD44s and the ERK1/2 signaling pathway.