Involvement of CD147 in regulation of multidrug resistance to P-gp substrate drugs and in vitro invasion in breast cancer cells

CD147/Basigin Is Involved in the Development of Malignant Tumors and T-Cell-Mediated Immunological Disorders via Regulation of Glycolysis

CD147/Basigin, a transmembrane glycoprotein belonging to the immunoglobulin superfamily, is a multifunctional molecule with various binding partners. CD147 binds to monocarboxylate transporters (MCTs) and supports their expression on plasma membranes. MTC-1 and MCT-4 export the lactic acid that is converted from pyruvate in glycolysis to maintain the intracellular pH level and a stable metabolic state. Under physiological conditions, cellular energy production is induced by mitochondrial oxidative phosphorylation. Glycolysis usually occurs under anaerobic conditions, whereas cancer cells depend on glycolysis under aerobic conditions. T cells also require glycolysis for differentiation, proliferation, and activation. Human malignant melanoma cells expressed higher levels of MCT-1 and MCT-4, co-localized with CD147 on the plasma membrane, and showed an increased glycolysis rate compared to normal human melanocytes. CD147 silencing by siRNA abrogated MCT-1 and MCT-4 membrane expression and disrupted glycolysis, inhibiting cancer cell activity. Furthermore, CD147 is involved in psoriasis. MCT-1 was absent on CD4+ T cells in CD147-deficient mice. The naïve CD4+ T cells from CD147-deficient mice exhibited a low capacity to differentiate into Th17 cells. Imiquimod-induced skin inflammation was significantly milder in the CD147-deficient mice than in the wild-type mice. Overall, CD147/Basigin is involved in the development of malignant tumors and T-cell-mediated immunological disorders via glycolysis regulation.

Ubiquitin C‑terminal hydrolase‑L1: A new cancer marker and therapeutic target with dual effects (Review)

Ubiquitin C-terminal hydrolase-L1 (UCH-L1), a member of the lesser-known deubiquitinating enzyme family, has deubiquitinase and ubiquitin (Ub) ligase activity and the role of stabilizing Ub. UCH-L1 was first discovered in the brain and is associated with regulating cell differentiation, proliferation, transcriptional regulation and numerous other biological processes. UCH-L1 is predominantly expressed in the brain and serves a role in tumor promotion or inhibition. There is still controversy about the effect of UCH-L1 dysregulation in cancer and its mechanisms are unknown. Extensive research to investigate the mechanism of UCH-L1 in different types of cancer is key for the future treatment of UCH-L1-associated cancer. The present review details the molecular structure and function of UCH-L1. The role of UCH-L1 in different types of cancer is also summarized and how novel treatment targets provide a theoretical foundation in cancer research is discussed.

Special AT-rich sequence binding protein 1 promotes multidrug resistance in gastric cancer by regulation of Ezrin to alter subcellular localization of ATP-binding cassette transporters

Multidrug resistance is a primary factor in the poor response to chemotherapy and subsequent death in gastric cancer patients. However, the molecular mechanisms involved remain unclear. In this study, the high expression of special AT-rich sequence binding protein 1 (SATB1) in gastric cancer was found to be associated with reduced sensitivity to various chemotherapy drugs. Our results demonstrate that SATB1 can promote chemotherapy resistance in gastric cancer in vitro and in vivo. SATB1 exerts its effect by enhancing the activity of multiple ATP-binding cassette (ABC) transporters (P-glycoprotein, multidrug resistance-associated protein, and breast cancer resistance protein) in gastric cancer cell lines. We also found that SATB1 affects ABC transporters by altering the subcellular localization of the ABC transporter rather than its expression. Subsequently, we confirmed that Ezrin binds to various ABC transporters and affects their subcellular localization. In addition, we found that SATB1 can also bind to the Ezrin promoter and regulate its expression. In the present study, we elucidate the mechanism of SATB1-mediated multidrug resistance in gastric cancer, providing a basis for SATB1 as a potential target for reversal of resistance.

ABC transporters in breast cancer: their roles in multidrug resistance and beyond

ATP-binding cassette (ABC) transporters are membrane-spanning proteins involved in cholesterol homeostasis, transport of various molecules in and out of cells and organelles, oxidative stress, immune recognition, and drug efflux. They are long implicated in the development of multidrug resistance in cancer chemotherapy. Existing clinical and molecular evidence has also linked ABC transporters with cancer pathogenesis, prognostics, and therapy. In this review, we aim to provide a comprehensive update on all ABC transporters and their roles in drug resistance in breast cancer (BC). For solid tumours such as BC, various ABC transporters are highly expressed in less differentiated subtypes and metastases. ABCA1, ABCB1 and ABCG2 are key players in BC chemoresistance. Restraining these transporters has evolved as a possible mechanism to reverse this phenomenon. Further, ABCB1 and ABCC1 are important in BC prognosis. Newer therapeutic approaches have been developed to target all these molecules to dysregulate their effect, reduce cell viability, induce apoptosis, and increase drug sensitivity. In the future, targeted therapy for specific genetic variations and upstream or downstream molecules can help improve patient prognosis.

Mini-Review: Can the Metastatic Cascade Be Inhibited by Targeting CD147/EMMPRIN to Prevent Tumor Recurrence?

Solid tumors metastasize very early in their development, and once the metastatic cell is lodged in a remote organ, it can proliferate to generate a metastatic lesion or remain dormant for long periods. Dormant cells represent a real risk for future tumor recurrence, but because they are typically undetectable and insensitive to current modalities of treatment, it is difficult to treat them in time. We describe the metastatic cascade, which is the process that allows tumor cells to detach from the primary tumor, migrate in the tissue, intravasate and extravasate the lymphatics or a blood vessel, adhere to a remote tissue and eventually outgrow. We focus on the critical enabling role of the interactions between tumor cells and immune cells, especially macrophages, in driving the metastatic cascade, and on those stages that can potentially be targeted. In order to prevent the metastatic cascade and tumor recurrence, we would need to target a molecule that is involved in all of the steps of the process, and evidence is brought to suggest that CD147/EMMPRIN is such a protein and that targeting it blocks metastasis and prevents tumor recurrence.

The β-adrenergic receptor antagonist propranolol offsets resistance mechanisms to chemotherapeutics in diverse sarcoma subtypes: a pilot study

Standard chemotherapy for soft tissue sarcomas has shown limited efficacy. Here, we sought to evaluate whether β-adrenergic receptor (β-AR) signalling contributed to the progression of sarcomas and therapy resistance. To assess the translational potential of β-adrenergic receptors, we performed immunohistochemical detection of β1-AR, β2-AR and β3-AR in leiomyosarcoma, liposarcoma and angiosarcoma tissue specimens, reporting the results scored for the intensity. By using established and patient-derived sarcoma cells, we demonstrated the antitumour potential of the pharmacological targeting of β-ARs with the nonselective β-blocker propranolol in such sarcomas. Of note, pharmacological β-AR inhibition synergized with doxorubicin in inhibiting the cell viability of liposarcoma and leiomyosarcoma cells and increased the response to docetaxel in angiosarcoma- and solitary fibrous tumour (SFT)-patient-derived cells. Notably, the SFT patient was treated with the combination of propranolol and docetaxel, reporting prolonged disease control. Mechanistically, we found that propranolol reduced the activity of the multidrug resistance efflux pump P-gp, thereby increasing the intracellular doxorubicin concentration and antitumour activity. In addition, propranolol attenuated the Akt-dependent survival signal induced by doxorubicin and strongly reduced the activation of the NF-kB/COX-2 pathway, increasing cell sensitivity to docetaxel. Overall, our study highlighted the therapeutic potential of propranolol, alone or in rational combination therapies, for sarcoma treatment.

Rociletinib (CO-1686) enhanced the efficacy of chemotherapeutic agents in ABCG2-overexpressing cancer cells in vitro and in vivo

Overexpression of adenosine triphosphate (ATP)-binding cassette subfamily G member 2 (ABCG2) in cancer cells is known to cause multidrug resistance (MDR), which severely limits the clinical efficacy of chemotherapy. Currently, there is no FDA-approved MDR modulator for clinical use. In this study, rociletinib (CO-1686), a mutant-selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), was found to significantly improve the efficacy of ABCG2 substrate chemotherapeutic agents in the transporter-overexpressing cancer cells in vitro and in MDR tumor xenografts in nude mice, without incurring additional toxicity. Mechanistic studies revealed that in ABCG2-overexpressing cancer cells, rociletinib inhibited ABCG2-mediated drug efflux and increased intracellular accumulation of ABCG2 probe substrates. Moreover, rociletinib, inhibited the ATPase activity, and competed with [¹²⁵I] iodoarylazidoprazosin (IAAP) photolabeling of ABCG2. However, ABCG2 expression at mRNA and protein levels was not altered in the ABCG2-overexpressing cells after treatment with rociletinib. In addition, rociletinib did not inhibit EGFR downstream signaling and phosphorylation of protein kinase B (AKT) and extracellular signal-regulated kinase (ERK). Our results collectively showed that rociletinib reversed ABCG2-mediated MDR by inhibiting ABCG2 efflux function, thus increasing the cellular accumulation of the transporter substrate anticancer drugs. The findings advocated the combination use of rociletinib and other chemotherapeutic drugs in cancer patients with ABCG2-overexpressing MDR tumors.

Isoorientin Decreases Cell Migration via Decreasing Functional Activity and Molecular Expression of Proton-Linked Monocarboxylate Transporters in Human Lung Cancer Cells

Aggressive tumor cells mainly rely on glycolysis, and further release vast amounts of lactate and protons by monocarboxylate transporter (MCT), which causes a higher intracellular pH (pH_i) and acidic extracellular pH. Isoorientin, a principle flavonoid compound extracted from several plant species, shows various pharmacological activities. However, effects of isoorientin on anticancer and MCT await to explore in human lung cancer cells. Human lung cancer tissues were obtained from cancer patients undergoing surgery, while the human lung adenocarcinoma cells (A549) were bought commercially. Change of pH_i was detected by microspectrofluorometry method with a pH-sensitive fluorescent dye, BCECF. MTT and wound-healing assay were used to detect the cell viability and migration, respectively. Western blot techniques and immunocytochemistry staining were used to detect the protein expression. Our results indicated that the expression of MCTs1/4 and CD147 were upregulated significantly in human lung tissues. In experiments of A549 cells, under HEPES-buffer, the resting pH_i was 7.47, and isoorientin (1-300μM) inhibited functional activity of MCT concentration-dependently (up to -42%). Pretreatment with isoorientin (3-100μM) for 24h, MCT activity and cell migration were significantly inhibited (-25% and -40%, respectively), while the cell viability was not affected. Moreover, the expression of MCTs1/4, CD147, and matrix metalloproteinase (MMP) 2/9 were significantly down regulated. In summary, MCTs1/4 and CD147 are significantly upregulated in human lung adenocarcinoma tissues, and isoorientin inhibits cells-migration by inhibiting activity/expression of MCTs1/4 and MMPs2/9 in human lung cancer cells. These novel findings suggest that isoorientin could be a promising pharmacological agent for lung cancer.

Recent Advances in the Studies of Molecular Mechanisms Regulating Multidrug Resistance in Cancer Cells

Here we present new approaches to better understanding multidrug resistance (MDR) development in cancer cells, such as identification of components of a complex process of MDR evolution. Recent advances in the studies of MDR are discussed: 1) chemotherapy agents might be involved in the selection of cancer stem cells resulting in the elevated drug resistance and enhanced tumorigenicity; 2) cell-cell interactions have a great effect on the MDR emergence and evolution; 3) mechanotransduction is an important signaling mechanism in cell-cell interactions; 4) proteins of the ABC transporter family which are often involved in MDR might be transferred between cells via microvesicles (epigenetic MDR regulation); 5) proteins providing cell-to-cell transfer of functional P-glycoprotein (MDR1 protein) via microvesicles have been investigated; 6) P-glycoprotein may serve to regulate apoptosis, as well as transcription and translation of target genes/proteins. Although proving once again that MDR is a complex multi-faceted process, these data open new approaches to overcoming it.

Improvement of chemosensitivity and inhibition of migration via targeting tumor epithelial-to-mesenchymal transition cells by ADH-1-modified liposomes

How to overcome drug resistance and prevent tumor metastasis is key to the success of malignant tumor therapy. In this paper, ADH-1 peptide-modified liposomes (A-LP) have been successfully constructed for restoring chemosensitivity and suppressing cancer cell migration. With a particle size of about 90 nm, this functionalized nanocarrier was loaded with fluorescent probe or paclitaxel (PTX). Cellular uptake studies showed that A-LP facilitated the delivery of anticancer drug to tumor cells undergoing EMT. Interestingly, this nanocarrier enhanced chemosensitivity by assessing the cell activity using CCK-8 assay. Further, the results of Wound scratch assay and Transwell migration assay showed the inhibition effect of this nanocarrier on tumor cell migration. Moreover, this nanocarrier exhibited significant tumor-targeting ability and anti-tumor efficacy in vivo. Collectively, A-LP might be a novel targeted drug delivery system to enhance the efficacy of chemotherapy and prevent tumor metastasis.

Cluster of differentiation 147 mediates chemoresistance in breast cancer by affecting vacuolar H+-ATPase expression and activity

Vacuolar H⁺-ATPase (V-ATPase) serves a key role in adjusting and maintaining the intracellular pH, as well as in regulating the drug resistance of tumor cells. In recent years, the expression level of V-ATPase has been considered to be able to predict the sensitivity of breast cancer cells to chemotherapy drugs. Cluster of differentiation 147 (CD147) is known to serve a key role in the development and progression of breast cancer. The present study aimed to identify the role CD147 and V-ATPase in chemoresistance in breast cancer, and to characterize the regulation of CD147 on V-ATPase. Firstly, the expression levels of CD147 and V-ATPase were detected in chemotherapy-resistance breast cancer samples. It was demonstrated that V-ATPase was highly expressed in chemotherapy-resistance breast cancer samples, and that its expression was correlated with CD147 expression. Subsequently, MCF-7 and MDA-MB-231 cells were used to study the regulatory effect of CD147 on the expression and function of V-ATPase. Gene transfection or small interfering RNA transfection were used to control the expression of CD147 in the two cell lines. The results revealed that the overexpression of CD147 increased the expression of V-ATPase in MCF-7 cells, whereas CD147 knockdown decreased V-ATPase expression in MDA-MB-231 cells. It was also observed that CD147 affected the V-ATPase activity, regulating the transmembrane pH gradient of cancer cells. These results demonstrated that CD147 was associated with the sensitivity of chemotherapeutic drugs of epirubicin and docetaxel, while pantoprazole was able to partially reverse the CD147-mediated chemoresistance in breast cancer. Therefore, the current study provided a possible mechanism for further examination of drug resistance in breast cancer.

CD147 knockdown improves the antitumor efficacy of trastuzumab in HER2-positive breast cancer cells

Trastuzumab is widely used in the clinical treatment of human epidermal growth factor receptor-2 (HER2)-positive breast cancer, but the patient response rate is low. CD147 stimulates cancer cell proliferation, migration, metastasis and differentiation and is involved in chemoresistance in many types of cancer cells. Whether CD147 alters the effect of trastuzumab on HER2-positive breast cancer cells has not been previously reported. Our study confirmed that CD147 suppression enhances the effects of trastuzumab both in vitro and in vivo. CD147 suppression increased the inhibitory rate of trastuzumab and cell apoptosis in SKBR3, BT474, HCC1954 and MDA-MB453 cells compared with the controls. Furthermore, CD147 knockdown increased expression of cleaved Caspase-3/9 and poly (ADP-ribose) polymerase (PARP) and decreased both mitogen-activated protein kinase (MAPK) and Akt phosphorylation in the four cell lines. In an HCC1954 xenograft model, trastuzumab achieved greater suppression of tumor growth in the CD147-knockdown group than in the shRNA negative control (NC) group. These data indicated that enhancement of the effect of trastuzumab on HER2-positive cells following CD147 knockdown might be attributed to increased apoptosis and decreased phosphorylation of signaling proteins. CD147 may be a key protein for enhancing the clinical efficacy of trastuzumab.

The importance of EGFR as a biomarker in molecular apocrine breast cancer

Molecular apocrine breast cancer (MABC) is a molecular subtype with a poor prognosis, and there is urgent need to find new therapeutic targets. Epidermal growth factor receptor (EGFR) plays an important part in regulating the biological behavior of tumor cells, and EGFR-targeted drugs have already been used in therapy for lung and colorectal cancers. The purpose of this study was to analyze the significance of EGFR expression in MABC. A total of 400 patients with invasive breast cancer were analyzed, including 200 MABC and 200 non-MABC cases. Immunohistochemistry and immunofluorescence were carried out to evaluate the expression of estrogen receptor, progesterone receptor, androgen receptor (AR), EGFR, epidermal growth factor receptor 2 (HER2), and other biomarkers. Two hundred twelve (53%) cases were positive for EGFR expression, including 173 MABC and 39 non-MABC cases. EGFR expression was positively associated with AR expression in MABC, as well as with more advanced tumor stage and high Ki67 expression. Patients with EGFR expression had worse outcomes than those without. As a prognosis biomarker, EGFR was significantly associated with poorer clinical outcomes, and the co-expression of EGFR and HER2 often predicted worse outcomes in MABC. This study suggests that the identification of new targets such as HER2 and EGFR may help with assessing the prognosis of patients with MABC. Using both AR and EGFR as therapeutic targets may be especially important in MABC and may help to guide the choice of suitable treatments for individual breast cancer patients.

Proteins regulating the intercellular transfer and function of P-glycoprotein in multidrug-resistant cancer

Chemotherapy is an essential part of anticancer treatment. However, the overexpression of P-glycoprotein (P-gp) and the subsequent emergence of multidrug resistance (MDR) hampers successful treatment clinically. P-gp is a multidrug efflux transporter that functions to protect cells from xenobiotics by exporting them out from the plasma membrane to the extracellular space. P-gp inhibitors have been developed in an attempt to overcome P-gp-mediated MDR; however, lack of specificity and dose limiting toxicity have limited their effectiveness clinically. Recent studies report on accessory proteins that either directly or indirectly regulate P-gp expression and function and which are necessary for the establishment of the functional phenotype in cancer cells. This review discusses the role of these proteins, some of which have been recently proposed to comprise an interactive complex, and discusses their contribution towards MDR. We also discuss the role of other pathways and proteins in regulating P-gp expression in cells. The potential for these proteins as novel therapeutic targets provides new opportunities to circumvent MDR clinically.

UCH-L1 promotes invasion of breast cancer cells through activating Akt signaling pathway

As a de-ubiquitin enzyme, ubiquitin C-terminal hydrolase (UCH)-L1 has been shown to be overexpressed in several human cancers. However, the function of UCH-L1 in invasion of breast cancers is still unclear. Here we report that the expression of UCH-L1 is significantly higher in cancer cells with higher invasive ability. While ectopic UCH-L1 expression failed to alter cell proliferation in MCF-7 cells, it caused a significant upregulation of cellular invasion. Furthermore, siRNA mediated knockdown of UCH-L1 led to suppression of invasion in UCH-L1 overexpressing MCF-7 cells. In order to identify molecular mechanisms underlying these observations, a novel in vitro proximity-dependent biotin identification method was developed by fusing UCH-L1 protein with a bacterial biotin ligase (Escherichia coli BirA R118G, BioID). Streptavidin magnetic beads pulldown assay revealed that UCH-L1 can interact with Akt in MCF-7 cells. Pulldown assay with His tagged recombinant UCH-L1 protein and cell lysate from MCF-7 cells further demonstrated that UCH-L1 preferentially binds to Akt2 for Akt activation. Finally, we demonstrated that overexpression of UCH-L1 led to activation of Akt as evidenced by upregulation of phosphorylated Akt. Thus, these findings demonstrated that UCH-L1 promotes invasion of breast cancer cells and might serve as a potential therapeutic target for treatment of human patients with breast cancers.

UCH-L1-containing exosomes mediate chemotherapeutic resistance transfer in breast cancer

BACKGROUND

Chemotherapy resistance has become a serious challenge in the treatment of breast cancer. Previous studies showed cells can transfer proteins, including those responsible for drug resistance to adjacent cells via exosomes.

METHODS

The switches of drug resistance via exosomes transfer were assessed by CellTiter-Blue Viability assay, flow cytometry, and immunostaining analysis. Relative protein levels of Ubiquitin carboxyl terminal hydrolase-L1 (UCH-L1), P-glycoprotein (P-gp), extracellular-signal regulated protein kinase1/2 (ERK1/2), and phospho-extracellular-signal regulated protein kinase1/2 (p-ERK1/2) were measured by Western blot. Immunohistochemistry was performed on 93 breast cancer samples to assess the associations of UCH-L1 levels with immunofluorescence value of UCH-L1 in circulating exosomes.

RESULT

The Adriamycin-resistant human breast cancer cells (MCF7/ADM) secreted exosomes carrying UCH-L1 and P-gp proteins into the extracellular microenvironment then integrated into Adriamycin-sensitive human breast cancer cells (MCF7/WT) in a time-dependent manner, transferring the chemoresistance phenotype. Notably, in blood samples from patients with breast cancer, the level of exosomes carrying UCH-L1 before chemotherapy was significantly negatively correlated with prognosis.

CONCLUSION

Our study demonstrated that UCH-L1-containing exosomes can transfer chemoresistance to recipient cells and these exosomes may be useful as non-invasive diagnostic biomarkers for detection of chemoresitance in breast cancer patients, achieving more effective and individualized chemotherapy.

Lentivirus mediated RNA interference of EMMPRIN (CD147) gene inhibits the proliferation, matrigel invasion and tumor formation of breast cancer cells

BACKGROUND

Overexpression of extracellular matrix metalloproteinase inducer (EMMPRIN) or cluster of differentiation 147 (CD147), a glycoprotein enriched on the plasma membrane of tumor cells, promotes proliferation, invasion, metastasis, and survival of malignant tumor cells. In this study, we sought to examine the expression of EMMPRIN in breast tumors, and to identify the potential roles of EMMPRIN on breast cancer cells.

METHODS

EMMPRIN expression in breast cancer tissues was assessed by immunohistochemistry. We used a lentivirus vector-based RNA interference (RNAi) approach expressing short hairpin RNA (shRNA) to knockdown EMMPRIN gene in breast cancer cell lines MDA-MB-231 and MCF-7. In vitro, Cell proliferative, invasive potential were determined by Cell Counting Kit (CCK-8), cell cycle analysis and matrigel invasion assay, respectively. In vivo, tumorigenicity was monitored by inoculating tumor cells into breast fat pad of female nude mice.

RESULTS

EMMPRIN was over-expressed in breast tumors and breast cancer cell lines. Down-regulation of EMMPRIN by lentivirus vector-based RNAi led to decreased cell proliferative, decreased matrigel invasion in vitro, and attenuated tumor formation in vivo.

CONCLUSION

High expression of EMMPRIN plays a crucial role in breast cancer cell proliferation, matrigel invasion and tumor formation.

Rack1 Mediates the Interaction of P-Glycoprotein with Anxa2 and Regulates Migration and Invasion of Multidrug-Resistant Breast Cancer Cells

The emergence of multidrug resistance is always associated with more rapid tumor recurrence and metastasis. P-glycoprotein (P-gp), which is a well-known multidrug-efflux transporter, confers enhanced invasion ability in drug-resistant cells. Previous studies have shown that P-gp probably exerts its tumor-promoting function via protein-protein interaction. These interactions were implicated in the activation of intracellular signal transduction. We previously showed that P-gp binds to Anxa2 and promotes the invasiveness of multidrug-resistant (MDR) breast cancer cells through regulation of Anxa2 phosphorylation. However, the accurate mechanism remains unclear. In the present study, a co-immunoprecipitation coupled with liquid chromatography tandem mass spectrometry-based interactomic approach was performed to screen P-gp binding proteins. We identified Rack1 as a novel P-gp binding protein. Knockdown of Rack1 significantly inhibited proliferation and invasion of MDR cancer cells. Mechanistic studies demonstrated that Rack1 functioned as a scaffold protein that mediated the binding of P-gp to Anxa2 and Src. We showed that Rack1 regulated P-gp activity, which was necessary for adriamycin-induced P-gp-mediated phosphorylation of Anxa2 and Erk1/2. Overall, the findings in this study augment novel insights to the understanding of the mechanism employed by P-gp for promoting migration and invasion of MDR cancer cells.

Involvement of CD147 on multidrug resistance through the regulation of P-glycoprotein expression in K562/ADR leukemic cell line

The relationship between P-gp and CD147 in the regulation of MDR in leukemic cells has not been reported. This study aimed to investigate the correlation between CD147 and P-gp in the regulation of drug resistance in the K562/ADR leukemic cell line. The results showed that drug-resistant K562/ADR cells expressed significantly higher P-gp and CD147 levels than drug-free K562/ADR cells. To determine the regulatory effect of CD147 on P-gp expression, anti-CD147 antibody MEM-M6/6 significantly decreased P-gp and CD147 mRNA and protein levels. This is the first report to show that CD147 mediates MDR in leukemia through the regulation of P-gp expression.

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High expression levels of P-gp and CD147 in drug-resistant cells.

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MEM-M6/6 antibody decreases both CD147 and P-gp expression.

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CD147 mediates MDR phenotype in leukemia through the regulation of P-gp expression.

EGFR/HER2 inhibitors effectively reduce the malignant potential of MDR breast cancer evoked by P-gp substrates in vitro and in vivo

Multidrug resistance (MDR) induced by chemotherapy in breast cancer frequently leads to tumor invasion, metastasis and poor clinical outcome. We preliminarily found that the epidermal growth factor receptor (EGFR) is involved in enhancing the malignant potential of MDR breast cancer cells, but the mechanism remains unclear. In the present study, we demonstrated in vitro and in vivo that EGFR/HER2 promote the invasive and metastatic abilities of MDR breast cancer. More importantly, a new function of EGFR/HER2 inhibitors was revealed for the first time, which could improve the treatment efficacy of breast cancer by reversing the MDR process rather than by inhibiting tumor growth. Firstly, using quantitative real‑time PCR and western blot analysis, we found that overexpression of EGFR/HER2 in MCF7/Adr cells upregulated CD147 and MMP2/9 at both the transcription and protein expression levels, which promoted tumor cell migration, as determined using an in vitro invasion assay. Secondly, the upregulated levels of CD147 and MMP2/9 were decreased when EGFR/HER2 activity was inhibited, and therefore tumor invasion was also significantly inhibited. These phenomena were also demonstrated in nude mouse assays. Additionally, in MDR breast cancer patients, we found that overexpression of EGFR and P‑gp levels led to shorter overall survival (OS) and disease‑free survival (DFS) by IHC assays and Kaplan‑Meier survival analysis. In conclusion, EGFR/HER2 play a crucial role in enhancing CD147 and MMP expression to establish favorable conditions for invasion/metastasis in MDR breast cancer. The scope of application of EGFR/HER2 inhibitors may be expanded in EGFR/HER2‑positive patients. We suggest that MDR breast cancer patients may benefit from novel therapies targeting EGFR/HER2.

Elevated STAT3 Signaling-Mediated Upregulation of MMP-2/9 Confers Enhanced Invasion Ability in Multidrug-Resistant Breast Cancer Cells

The development of multidrug resistance greatly impedes effective cancer therapy. Recent advances in cancer research have demonstrated that acquisition of multidrug resistance by cancer cells is usually accompanied by enhanced cell invasiveness. Several lines of evidence indicated that cross activation of other signaling pathways during development of drug resistance may increase invasive potential of multidrug-resistant (MDR) cancer cells. However, the accurate mechanism of this process is largely undefined. In this study, to better understand the associated molecular pathways responsible for cancer progression induced by drug resistance, a MDR human breast cancer cell line SK-BR-3/EPR with P-glycoprotein overexpression was established using stepwise long-term exposure to increasing concentration of epirubicin. The SK-BR-3/EPR cell line exhibited decreased cell proliferative activity, but enhanced cell invasive capacity. We showed that the expression of metastasis-related matrix metalloproteinase (MMP)-2/9 was elevated in SK-BR-3/EPR cells. Moreover, SK-BR-3/EPR cells showed elevated activation of STAT3. Activation of STAT3 signaling is responsible for enhanced invasiveness of SK-BR-3/EPR cells through upregulation of MMP-2/9. STAT3 is a well-known oncogene and is frequently implicated in tumorigenesis and chemotherapeutic resistance. Our findings augment insight into the mechanism underlying the functional association between MDR and cancer invasiveness.

CD147 and Ki-67 overexpression confers poor prognosis in squamous cell carcinoma of oral tongue: a tissue microarray study

OBJECTIVE

Squamous cell carcinoma of the oral tongue (SCCOT) exhibits high risk for recurrence and regional metastasis even after surgical resection. We assessed the clinicopathologic and prognostic significance of a group of functionally related biomarkers.

STUDY DESIGN

We used a tissue microarray consisting of SCCOT from 32 patients for this study. These patients were treated at the University of Texas MD Anderson Cancer Center from 1995 to 2008. Biomarker expression levels were examined by immunohistochemistry and graded semiquantitatively to determine their prognostic significance.

RESULTS

CD147 and Tp63 expressions were significantly associated with a higher T stage and Ki-67 labeling index, as well as a shorter overall survival (OS) rate. Expression of Tp63 associated positively with poorly differentiated histology. There was significant association of Tp63 with the expression levels of CD147 and Glut-1. Glut-1 overexpression was marginally associated with a higher T stage. There was no prognostic significance of CD44 v6 expression in SCCOT.

CONCLUSION

SCCOT with CD147 overexpression in combination with high Ki-67 labeling index had poor OS. CD147 and Ki-67 overexpression is associated with aggressive disease with poor prognosis in SCCOT.

Lapatinib antagonizes multidrug resistance-associated protein 1-mediated multidrug resistance by inhibiting its transport function

Lapatinib, a tyrosine kinase inhibitor, is used in the treatment of advanced or metastatic breast cancer overexpressing human epidermal receptor 2 (HER2). Lapatinib can modulate the function of ATP-binding cassette (ABC) transporters (ABCB1 and ABCG2), which are the major mechanism responsible for multidrug resistance (MDR) in cancer. In this study, we investigated the effect of lapatinib on multidrug resistance-associated protein 1 (MRP1 [ABCC1]), MRP2 (ABCC2), MRP4 (ABCC4) and lung relative resistance protein (LRP) drug efflux pumps. We demonstrated that lapatinib could enhance the efficacy of conventional chemotherapeutic agents in MRP1-overexpressing cells in vitro and in vivo, but no effect in MRP2-, MPR4- and LRP-overexpressing cells. Furthermore, lapatinib significantly increased the accumulation of rhodamine 123 (Rho123) and doxorubicin (DOX) in MRP1-overexpressing cells. However, lapatinib did not alter the protein or mRNA expression levels of MRP1. Further studies showed that the level of phosphorylation of AKT and extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) were not altered at the indicated concentrations of lapatinib. In conclusion, lapatinib enhanced the efficacy of conventional chemotherapeutic agents in MRP1-overexpressing cells by inhibiting MRP1 transport function without altering the level of AKT or ERK1/2 phosphorylation. These findings will encourage the clinical research of lapatinib combined with conventional chemotherapeutic drugs in MRP1-overexpressing cancer patients.

Involvement of CUL4A in regulation of multidrug resistance to P-gp substrate drugs in breast cancer cells

CUL4A encodes a core component of a cullin-based E3 ubiquitin ligase complex that regulates many critical processes such as cell cycle progression, DNA replication, DNA repair and chromatin remodeling by targeting a variety of proteins for ubiquitination and degradation. In the research described in this report we aimed to clarify whether CUL4A participates in multiple drug resistance (MDR) in breast cancer cells. We first transfected vectors carrying CUL4A and specific shCUL4A into breast cancer cells and corresponding Adr cells respectively. Using reverse transcription polymerase chain reactions and western blots, we found that overexpression of CUL4A in MCF7 and MDA-MB-468 cells up-regulated MDR1/P-gp expression on both the transcription and protein levels, which conferred multidrug resistance to P-gp substrate drugs, as determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. On the other hand, silencing CUL4A in MCF7/Adr and MDA-MB-468/Adr cells led to the opposite effect. Moreover, ERK1/2 in CUL4A-overexpressing cells was highly activated and after treatment with PD98059, an ERK1/2-specific inhibitor, CUL4A-induced expression of MDR1/P-gp was decreased significantly. Lastly, immunohistochemistry in breast cancer tissues showed that P-gp expression had a positive correlation with the expression of CUL4A and ERK1/2. Thus, these results implied that CUL4A and ERK1/2 participated in multi-drug resistance in breast cancer through regulation of MDR1/P-gp expression.

P-glycoprotein associates with Anxa2 and promotes invasion in multidrug resistant breast cancer cells

Several recent studies have suggested that the acquisition of the multidrug resistance (MDR) phenotype is associated with elevated invasion and metastasis of tumor cells. P-glycoprotein (P-gp), the major determinant in the generation of the MDR phenotype, was reported to be correlated with a more aggressive phenotype and poor prognosis in many forms of malignancies. However, a clear understanding of the association is still lacking. We previously showed that Anxa2, a calcium-dependent phospholipid-binding protein, interacts with P-gp and contributes to the invasiveness of MDR breast cancer cells. In the present study, a strong positive correlation between MDR1 and Anxa2 mRNA expression in invasive breast cancer tissues during cancer progression was observed. In addition, exposure to adriamycin significantly enhanced motility in breast cancer cells and increased levels of P-gp and Anxa2. Moreover, inhibition of P-gp activity, using selective P-gp modulators, was found to significantly inhibit the invasive capacity of MCF-7/ADR cells without affecting the interaction and co-localization between P-gp and Anxa2. However, suppression of P-gp pump activity and knockdown of MDR1 expression both disrupted adriamycin-induced Anxa2 phosphorylation. Interestingly, P-gp was further demonstrated to interact with Src, a tyrosine kinase upstream of Anxa2. Taken together, our results indicate that P-gp may promote the invasion of MDR breast cancer cells by modulating the tyrosine phosphorylation of Anxa2. The interaction between Anxa2 and P-gp is possibly, at least in part, responsible for the association between MDR and invasive potential in breast cancer cells.

CD147 mediates chemoresistance in breast cancer via ABCG2 by affecting its cellular localization and dimerization

CD147 and ABCG2 both have been reported to mediate Multidrug resistance (MDR) in breast cancer. Recent study demonstrates that CD147 could form a complex with ABCG2 on the cell membrane in primary effusion lymphoma. However, whether these two molecules regulate each other in breast cancer and result in MDR is not clear. We established four MCF-7 cell lines transfected with CD147 and/or ABCG2 and found that CD147 could increase the expression and dimerization of ABCG2, affect its cellular localization and regulate its drug transporter function. The findings derived from cells were confirmed subsequently in clinic samples of chemotherapy-sensitive/resistant breast cancer.

A novel role of EMMPRIN/CD147 in transformation of quiescent fibroblasts to cancer-associated fibroblasts by breast cancer cells

We tested the novel hypothesis that EMMPRIN/CD147, a transmembrane glycoprotein overexpressed in breast cancer cells, has a previously unknown role in transforming fibroblasts to cancer-associated fibroblasts, and that cancer-associated fibroblasts in turn induce epithelial-to-mesenchymal transition of breast cancer cells. Co-culture of fibroblasts with breast cancer cells or treatment of fibroblasts with breast cancer cell conditioned culture medium or recombinant EMMPRIN/CD147 induced expression of α-SMA in the fibroblasts in an EMMPRIN/CD147-dependent manner and promoted epithelial-to-mesenchymal transition of breast cancer cells and enhanced cell migration potential. These findings support a novel role of EMMPRIN/CD147 in regulating the interaction between cancer and stroma.

CD147 promotes MTX resistance by immune cells through up-regulating ABCG2 expression and function

BACKGROUND

Methotrexate (MTX) is a drug used to treat psoriasis due to inducing immune cell apoptosis. However, certain patients show MTX resistant. CD147, highly expressed by psoriatic PBMCs, is assumed to regulate MTX sensitivity. The underlining mechanism is still relatively understudied.

OBJECTIVE

To understand the mechanisms of that CD147 promotes MTX resistance in immune cells.

METHODS

The expression of CD147 and ABCG2 in PBMCs from psoriatic patients, cellular apoptosis and intracellular MTX amount were measured. We also checked the cellular drug sensitivity of CHO (Chinese Hamster Ovary) cell lines with introduced CD147 and Jurkat T cells depeleted CD147. By immunoprecipitation, we detected the interaction between CD147 and ABCG2.

RESULTS

Both ABCG2 and CD147 are highly expressed in psoriatic PBMCs. Cultured in vitro, the PBMCs from psoriatic patients were more resistant to MTX-induced apoptosis comparing to PBMCs from healthy people. Further studies demonstrated that exogenous overexpression of CD147 in CHO cells increased ABCG2 protein level. After MTX treatment, CD147 overexpressing CHO cells showed lower apoptosis rate and lower intracellular MTX concentration. On the contrary, knockdown of CD147 by shRNA in Jurkat T cells decreased ABCG2 expression, as well as increased MTX-induced apoptosis and decreased MTX efflux. Immunoprecipitation experiment revealed that the trans-membrane domain of CD147 conferred its' interaction with ABCG2.

CONCLUSION

Our study suggests a role of CD147 in regulating ABCG2 transportation of MTX in immune cells. Strategies involving targeting CD147 could be considered in clinical treatment of psoriatic patients resistant to MTX.

CD147-dependent heterogeneity in malignant and chemoresistant properties of cancer cells

CD147 (alias emmprin or basigin), an integral plasma membrane glycoprotein and a member of the Ig superfamily, is widespread in normal tissues, but highly up-regulated in many types of malignant cancer cells. CD147 is multifunctional, with numerous binding partners. Recent studies suggest that complexes of CD147 with the hyaluronan receptor CD44 and associated transporters and receptor tyrosine kinases are enriched in the plasma membrane of cancer stem-like cells. Here, we show that subpopulations of tumor cell lines constitutively expressing high levels of cell-surface CD147 exhibit cancer stem-like cell properties; that is, they exhibit much greater invasiveness, anchorage-independent growth, spheroid formation, and drug resistance in vitro and higher tumorigenicity in vivo than those constitutively expressing low levels of cell-surface CD147. Primary CD147-rich cell subpopulations derived from mouse mammary adenocarcinomas also exhibit high levels of invasiveness and spheroid-forming capacity, whereas CD147-low cells do not. Moreover, localization at the plasma membrane of CD44, the EGF receptor, the ABCB1 and ABCG2 drug transporters, and the MCT4 monocarboxylate transporter is elevated in cells constitutively expressing high levels of cell-surface CD147. These results show that CD147 is associated with assembly of numerous pro-oncogenic proteins in the plasma membrane and may play a fundamental role in properties characteristic of cancer stem-like cells.

Glycomic alterations are associated with multidrug resistance in human leukemia

Correlations of disease phenotypes with glycosylation changes have been analyzed intensively in tumor biology field. In this study we describe glycomic alterations of multidrug resistance in human leukemia cell lines. Using multiple glycan profiling tools: real-time PCR for quantification of glycogenes, FITC-lectin binding for glycan profiling, and mass spectrometry for glycan composition, we compared the glycomics of drug-resistant K562/ADR cells with parental K562 line. The results showed that the expression of glycogenes, glycan profiling and N-glycan composition were different in K562/ADR cells, as compared with those in K562 cells, whereas O-glycans of the two cell lines showed no different mass spectra. Further analysis of the N-glycan regulation by way of tunicamycin application or PNGase F treatment in K562/ADR cells showed partial inhibition of biosynthesis and increased sensitivity to chemotherapeutic drugs in vitro. We targeted glycogene B3GNT8 and ST8SIA4, which were over-expressed in K562/ADR cells, and silenced the expression levels of two glycogenes after using RNA interference approach. The results showed that the silencing of B3GNT8 or ST8SIA4 in K562/ADR cells resulted in increased chemosensitivity to anti-tumor drugs. In conclusion, glycomic alterations are responsible for the overcoming multidrug resistance in human leukemia therapy and the N-linked oligosaccharides are associated with the drug resistance of cancer cells.

Special AT-rich sequence binding protein 1 regulates the multidrug resistance and invasion of human gastric cancer cells

Special AT-rich sequence binding protein 1 (SATB1) is a nuclear factor that functions as a global chromatin organizer to regulate gene expression. Recent studies have suggested an oncogenic role of SATB1 in breast cancer. However, the role of SATB1 in gastric cancer, especially in regulating the malignant phenotypes, including multidrug resistance (MDR) and metastasis, remains poorly understood. In this study, the aggressive human gastric cancer cell line SGC7901 and its corresponding MDR variant SGC7901/VCR cells were used as a model. SATB1 expression was examined by RT-PCR and western blot analysis. Results showed that SATB1 was upregulated in SGC7901/VCR cells. An in vitro drug sensitivity assay demonstrated a positive correlation between SATB1 expression levels and drug resistance. Gain and loss of SATB1 function experiments further demonstrated that SATB1 contributes to MDR by inhibiting the accumulation of vincristine (VCR) in gastric cancer cells and protecting the cells from VCR-induced apoptosis. In addition, SATB1 may promote the invasion of gastric cancer cells. The present study provides a novel insight into the oncogenic role of SATB1 in gastric cancer, suggesting that SATB1 is a promising target for the therapy of drug-resistant and invasive gastric cancer.

Up-regulation of Anxa2 gene promotes proliferation and invasion of breast cancer MCF-7 cells

OBJECTIVE

The metastatic ability of breast cancer cells with chemoresistant properties is higher when compared to that of their parental wild-type cells. Expression of AnnexinA2 (Anxa2), a 36-kDa calcium-dependent phospholipid binding protein, is increased in metastatic tumours and has been found to be associated with the phenotype of drug resistance and metastasis.

MATERIALS AND METHODS AND RESULTS

In the present study, we found that up-regulation of Anxa2 correlates with enhanced migration and invasion ability of MCF-7 breast cancer cells both in vitro and in vivo. Western blot analysis revealed that exposure to chemotherapeutic drugs may induce elevated expression of Anxa2. In addition, our data have shown that Anxa2 might influence proliferation, migration and invasion of MCF-7 cells by increasing expression of c-myc and cyclin D1 via activation of Erk1/2 signalling pathways.

CONCLUSION

Our findings suggest that up-regulation of Anxa2 may play an important role in modulating proliferation and invasion of breast cancer MCF-7 cells through regulation of many relevant downstream target genes.

Interaction of stellate cells with pancreatic carcinoma cells

Pancreatic cancer is characterized by its late detection, aggressive growth, intense infiltration into adjacent tissue, early metastasis, resistance to chemo- and radiotherapy and a strong “desmoplastic reaction”. The dense stroma surrounding carcinoma cells is composed of fibroblasts, activated stellate cells (myofibroblast-like cells), various inflammatory cells, proliferating vascular structures, collagens and fibronectin. In particular the cellular components of the stroma produce the tumor microenvironment, which plays a critical role in tumor growth, invasion, spreading, metastasis, angiogenesis, inhibition of anoikis, and chemoresistance. Fibroblasts, myofibroblasts and activated stellate cells produce the extracellular matrix components and are thought to interact actively with tumor cells, thereby promoting cancer progression. In this review, we discuss our current understanding of the role of pancreatic stellate cells (PSC) in the desmoplastic response of pancreas cancer and the effects of PSC on tumor progression, metastasis and drug resistance. Finally we present some novel ideas for tumor therapy by interfering with the cancer cell-host interaction.

Co-expression of CD147 (EMMPRIN), CD44v3-10, MDR1 and monocarboxylate transporters is associated with prostate cancer drug resistance and progression

Background:

The aim of this study is to seek an association between markers of metastatic potential, drug resistance-related protein and monocarboxylate transporters in prostate cancer (CaP).

Methods:

We evaluated the expression of invasive markers (CD147, CD44v3-10), drug-resistance protein (MDR1) and monocarboxylate transporters (MCT1 and MCT4) in CaP metastatic cell lines and CaP tissue microarrays (n=140) by immunostaining. The co-expression of CD147 and CD44v3-10 with that of MDR1, MCT1 and MCT4 in CaP cell lines was evaluated using confocal microscopy. The relationship between the expression of CD147 and CD44v3-10 and the sensitivity (IC₅₀) to docetaxel in CaP cell lines was assessed using MTT assay. The relationship between expression of CD44v3-10, MDR1 and MCT4 and various clinicopathological CaP progression parameters was examined.

Results:

CD147 and CD44v3-10 were co-expressed with MDR1, MCT1 and MCT4 in primary and metastatic CaP cells. Both CD147 and CD44v3-10 expression levels were inversely related to docetaxel sensitivity (IC₅₀) in metastatic CaP cell lines. Overexpression of CD44v3-10, MDR1 and MCT4 was found in most primary CaP tissues, and was significantly associated with CaP progression.

Conclusions:

Our results suggest that the overexpression of CD147, CD44v3-10, MDR1 and MCT4 is associated with CaP progression. Expression of both CD147 and CD44v3-10 is correlated with drug resistance during CaP metastasis and could be a useful potential therapeutic target in advanced disease.

RNAi-mediated silencing of CD147 inhibits tumor cell proliferation, invasion and increases chemosensitivity to cisplatin in SGC7901 cells in vitro

Background

CD147 is a widely distributed cell surface glycoprotein that belongs to the Ig superfamily. CD147 has been implicated in numerous physiological and pathological activities. Enriched on the surface of many tumor cells, CD147 promotes tumor growth, invasion, metastasis and angiogenesis and confers resistance to some chemotherapeutic drugs. In this study, we investigated the possible role of CD147 in the progression of gastric cancer.

Methods

Short hairpin RNA (shRNA) expressing vectors targeting CD147 were constructed and transfected into human gastric cancer cells SGC7901 and CD147 expression was monitored by quantitative realtime RT-PCR and Western blot. Cell proliferation, the activities of MMP-2 and MMP-9, the invasive potential and chemosensitivity to cisplatin of SGC7901 cells were determined by MTT, gelatin zymography, Transwell invasion assay and MTT, respectively.

Results

Down-regulation of CD147 by RNAi approach led to decreased cell proliferation, MMP-2 and MMP-9 activities and invasive potential of SGC7901 cells as well as increased chemosensitivity to cisplatin.

Conclusion

CD147 involves in proliferation, invasion and chemosensitivity of human gastric cancer cell line SGC7901, indicating that CD147 may be a promising therapeutic target for gastric cancer.

Tumor metabolism of lactate: the influence and therapeutic potential for MCT and CD147 regulation

Tumor metabolism consists of complex interactions between oxygenation states, metabolites, ions, the vascular network and signaling cascades. Accumulation of lactate within tumors has been correlated with poor clinical outcomes. While its production has negative implications, potentially contributing to tumor progression, the implications of the ability of tumors to utilize lactate can offer new therapeutic targets for the future. Monocarboxylate transporters (MCTs) of the SLC16A gene family influence substrate availability, the metabolic path of lactate and pH balance within the tumor. CD147, a chaperone to some MCT subtypes, contributes to tumor progression and metastasis. The implications and consequences of lactate utilization by tumors are currently unknown; therefore future research is needed on the intricacies of tumor metabolism. The possibility of metabolic modification of the tumor microenvironment via regulation or manipulation of MCT1 and CD147 may prove to be promising avenues of therapeutic options.

Anxa2 plays a critical role in enhanced invasiveness of the multidrug resistant human breast cancer cells

Multidrug resistance (MDR) is the major cause of failure in cancer chemotherapy. Recent reports even suggest that MDR is associated with elevated invasion and metastasis of tumor cells. In the current study, we used a proteomic approach to identify genes that play an important role in MDR induced cell migration. 2D-PAGE and MALDI-TOF/MS-based proteomics approach were used to separate and identify differentially expressed proteins between MCF-7 and MCF-7/ADR, a p-glycoprotein-overexpressing adriamycin-resistance breast cancer cell line. Annexin a2 (Anxa2) was identified as highly expressed in MCF-7/ADR cells, but not in MCF-7 cells. Small interference RNA-mediated gene suppression demonstrated that Anxa2 was required for enhanced cell proliferation and invasion of the MCF-7/ADR cells. Down-regulation of Anxa2 alone was not sufficient to revert the cell sensitivity to adriamycin, suggesting that Anxa2 was not required for MDR phenotype. Taken together, our results showed that expression of Anxa2 is enhanced when cancer cells, MCF-7, acquired drug resistance and it plays an essential role in MDR-induced tumor invasion.

CD147/basigin promotes progression of malignant melanoma and other cancers

CD147/basigin, a transmembrane protein belonging to the immunoglobulin super family, was originally cloned as a carrier of Lewis X carbohydrate antigen. CD147 is strongly related to cancer progression; it is highly expressed by various cancer cells including malignant melanoma (MM) cells and it plays important roles in tumor invasiveness, metastasis, cellular proliferation, and in vascular endothelial growth factor (VEGF) production, tumor cell glycolysis, and multi-drug resistance (MDR). CD147 on cancer cells induces matrix metalloproteinase expression by neighboring fibroblasts, leading to tumor cell invasion. In a nude mouse model of pulmonary metastasis from MM, the metastatic potential of CD147-expressing MM cells injected into the tail vein is abolished by CD147 silencing. CD147 enhances cellular proliferation and VEGF production by MM cells; it promotes tumor cell glycolysis by facilitating lactate transport in combination with monocarboxylate transporters, resulting in tumor progression. CD147 is responsible for the MDR phenotype via P-glycoprotein expression. These findings strongly suggest CD147 as a possible therapeutic target for overcoming metastasis and MDR, major obstacles to the effective treatment of malignant cancers.

Overexpression and involvement of special AT-rich sequence binding protein 1 in multidrug resistance in human breast carcinoma cells

Special AT-rich sequence binding protein (SATB) 1 has been proposed to act as a determinant for the acquisition of metastatic activity by controlling expression of a specific set of genes that promote metastatic activity. Here we found that SATB1 expression is upregulated in multidrug-resistant breast cancer cells that exhibit higher invasive potential than the parental cells. Apart from accelerating metastasis and inducing epithelial-mesenchymal transition, SATB1 was demonstrated to confer resistance to both P-glycoprotein-related and P-glycoprotein-non-related drugs on MCF7 cells, which was accompanied by decreasing accumulation of adriamycin in SATB1-overexpressing transfectants. SATB1 depletion could partially reverse the multidrug resistance (MDR) phenotype of MCF7/ADR in vitro and in vivo. The SATB1-induced P-glycoprotein-mediated MDR could be reversed by treatment with anti-P-glycoprotein mAb. Moreover, SATB1 plays an important role in anti-apoptotic activity in MCF7/ADR cells in response to adriamycin treatment, which suggests another mechanism contributing to SATB1-related MDR of breast cancers. These data provide new insights into the mode by which breast tumors acquire the MDR phenotype and also imply a role for SATB1 in this process.

A role for p53 in the regulation of extracellular matrix metalloproteinase inducer in human cancer cells

EMMPRIN, a transmembrane glycoprotein known to promote survival, invasion and metastasis of tumor cells through multiple pathways and mechanisms, has been found to be overexpressed in various types of cancer cells. Here we report that loss of the function of p53, a tumor suppressor protein that is mutated in approximately 50% of human cancers, contributes to the upregulation of EMMPRIN protein. We observed an inverse association between the activity of p53 and the level of EMMPRIN protein in several cancer cell lines. We further demonstrated that p53 is able to negatively regulate EMMPRIN protein, but downregulation of EMMPRIN by p53 is independent of repression of the EMMPRIN transcription. Furthermore, downregulation of EMMPRIN by p53 can be rescued by chloroquine, a lysosome inhibitor, but not by MG132, a proteasome inhibitor, suggesting an involvement of the lysosomal pathway in the p53-regulated degradation of EMMPRIN. Downregulation of EMMPRIN by p53 leads to a decrease in the activity of MMP-9 and an inhibition of tumor cell invasion. Our study suggests that the upregulation of EMMPRIN seen in many cancers can be attributed to, at least in part, the dysfunction of p53 and thus provides new evidence for the roles of p53 in tumor development and progression.

Twist1-mediated adriamycin-induced epithelial-mesenchymal transition relates to multidrug resistance and invasive potential in breast cancer cells

PURPOSE

Besides its therapeutic effects, chemotherapeutic agents also enhance the malignancy of treated cancers in clinical situations. Recently, epithelial-mesenchymal transition (EMT) has attracted attention in studies of tumor progression. We aimed to test whether transient Adriamycin treatment induces EMT and apoptosis simultaneously in cancer cells, clarify why the same type of cells responds differentially (i.e., apoptosis, EMT) to Adriamycin treatment, and elucidate the role of Twist1, the master regulator of EMT, in this process.

EXPERIMENTAL DESIGN

In unsynchronized MCF7 cells or cells synchronized at different phases, apoptosis, EMT, and concurrent events [multidrug resistance (MDR) and tumor invasion] after Adriamycin or/and Twist1 small interfering RNA treatment were examined in vitro and in vivo. The Adriamycin-induced Twist1 expression and the interaction of Twist1 with p53-Mdm2 were examined by immunoblotting and immunoprecipitation, respectively.

RESULTS

We showed in vitro that Adriamycin induced EMT and apoptosis simultaneously in a cell cycle-dependent manner. Only the cells undergoing EMT displayed enhanced invasion and MDR. Twist1 depletion completely blocked the mesenchymal transformation, partially reversed MDR, and greatly abolished invasion induced by Adriamycin. Also, we confirmed in vivo that Twist1 RNA interference improved the efficacy of Adriamycin for breast cancers. Further, Twist1 reduction in Adriamycin-treated cells promoted p53-dependent p21 induction and disrupted the association of p53 with Mdm2.

CONCLUSIONS

Our studies show the diverse responses to Adriamycin treatment in cells at different phases, suggest an unrecognized role of EMT in regulating MDR and invasion, and show the efficacy of Twist1 RNA interference in Adriamycin-based chemotherapies for breast cancer.

Cediranib (recentin, AZD2171) reverses ABCB1- and ABCC1-mediated multidrug resistance by inhibition of their transport function

PURPOSE

Cediranib (recentin, AZD2171) is an oral small-molecule multiple receptor tyrosine kinases inhibitor. Here we investigate the ability of cediranib to reverse tumor multidrug resistance (MDR) due to overexpression of ABCB1 (P-glycoprotein) and ABCC1 (MRP1) transporters.

METHODS

KBv200,MCF-7/adr, C-A120 and their parental sensitive cell lines KB, MCF-7 and KB-3-1 were used for reversal study. The intracellular accumulations of doxorubicin and rhodamine 123 were determined by flow cytometry. The expressions levels of ABCB1 and ABCC1 were investigated by Western blot and RT-PCR analyses. ATPase activity assay were performed by Luminescence. The functions of ERK in MCF-7/adr were investigated by RNA interference.

RESULTS

Cediranib significantly enhanced the sensitivity of ABCB1 or ABCC1 substrates in MDR cells, with no effect found on sensitive cells. However, the expressions of these transporters were not affected and the reversal activity of cediranib was not related to the phosphorylation of AKT or ERK1/2. Further studies showed that cediranib inhibited ATPase activity of ABCB1 (P-glycoprotein) in a dose-dependent manner.

CONCLUSIONS

Cediranib reverses ABCB1- and ABCC1-mediated MDR by directly inhibiting their drug efflux function. These findings may be useful for cancer combinational therapy with cediranib in the clinic.

Expression of CD147 mediates tumor cells invasion and multidrug resistance in hepatocellular carcinoma

Multidrug resistant (MDR) tumor cells over-expressing P-glycoprotein exhibit variation in invasive behavior. To investigate the mechanisms, we analyzed the expression of CD147. The results showed that CD147 expression was increased in HepG2/Adr cells, as compared to HepG2 cells. The MDR cells produced more MMP11 and MDR1, which promoted HepG2/Adr cells invasion and increased resistance to chemotherapeutic drugs. On the other hand, CD147 silencing in HepG2/Adr cells by RNAi led to the opposite effect. Treatment of tumor cells with U-0126, an inhibitor of MAPK/Erk, also down-regulated MMP11 and MDR1 expression. Thus, CD147 may functionally mediate tumor cells invasion and MDR.