SMARCAD1 knockdown uncovers its role in breast cancer cell migration,invasion, and metastasis

Objective: Breast cancer is the most common cancer seen in women worldwide and breast cancer patients are at high risk of recurrence in the form of metastatic disease. Identification of genes associated with invasion and metastasis is crucial in order to develop novel anti-metastasis targeted therapy. It has been demonstrated that the DEAD-BOX helicase DP103 was implicated in breast cancer invasion and metastasis. SMARCAD1 is also a DEAD/H box-containing helicase, suggested to play a role in genetic instability. However, its involvement in cancer migration, invasion, and metastasis has never been explored.

Research design and methods: Using two different designs of shRNA targeting SMARCAD1, we investigated the impact of SMARCAD1 knockdown on the migration, invasion, and metastasis potential of the breast cancer cells MDA-MB-231 and T47D.

Results: We observed that SMARCAD1 knockdown in the invasive breast cancer cells MDA-MB-231, unlike in the non-invasive breast cancer cells T47D, was associated with an increased cell-cell adhesion and a significant decrease in cell migration, invasion, and metastasis due at least in part to a strong inhibition of STAT3 phosphorylation.

Conclusions: These results indicate that SMARCAD1 is involved in breast cancer metastasis and can be a promising target for metastatic breast cancer therapy.     

Inhibitory effects of isoliquiritigenin on the migration and invasion of human breast cancer cells

Introduction: Isoliquiritigenin (ISL) is a natural phenolic compound extracted from licorice. Previous studies have shown that ISL is a potent antioxidant with anti-inflammatory and antitumor activities. The anti-invasive activity of ISL was still unclear. The actual causes of death for most breast cancer patients were due to the tumor metastasis. Attenuating the expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs) is well known to prevent tumor metastasis.

Objectives: The purpose of this study is to investigate the effects of ISL on VEGF and MMP expression in highly metastatic human breast cancer cell line, MDA-MB-231.

Results: ISL reduced the secretions and protein levels of VEGF. The VEGF upstream regulatory protein, hypoxia-inducible factor 1-alpha (HIF-1α), was also reduced after ISL treatment. Moreover, ISL inhibited the expression and gelatinolytic activity of MMP-2 and MMP-9 which were confirmed by western blot and gelatin zymography assay. Additionally, the anti-migratory activity of ISL was further confirmed by chamber migration assay and wound migration assay. Upstream signaling pathways, including the expression of phosphatidylinositol-3 kinase (PI3K), the phosphorylation of p38 and Akt kinase and NF-κB DNA binding activity, were suppressed by ISL.

Conclusion: These findings suggest that ISL suppresses the migration of MDA-MB-231 cells by inhibiting the upstream signaling pathways.     

人参皂苷Rg3对乳腺癌MCF-7细胞增殖和侵袭的影响

目的 观察人参皂苷Rg3对雌激素受体阳性的乳腺癌细胞MCF-7增殖和侵袭的影响,并探讨其可能的作用机制。方法 采用MTT法检测细胞的增殖能力,流式细胞仪分析细胞周期分布以及凋亡比率,通过Transwell小室观察细胞侵袭力,RT-PCR法检测细胞中的MMP-9 mRNA的表达。结果 与对照组相比,人参皂苷Rg3能显著抑制MCF-7细胞的增殖;G₀/G₁期及S期细胞比例减少,而G₂/M期细胞比例显著增加;同时细胞凋亡比率亦明显提升,而细胞侵袭指数降低,且呈现良好的剂量、时间依赖性。同时人参皂苷Rg3还能显著抑制细胞中MMP-9 mRNA的表达水平(P<0.05)。结论 人参皂苷Rg3能抑制MCF-7细胞的增殖和侵袭,其作用机制可能与其能降低MMP-9基因的表达有关。     

Evaluation of anti-invasion effect of cannabinoids on human hepatocarcinoma cells

Context: Cancer is a disease characterized by abnormal growth of cells. One of the most common types of liver cancers is called hepatocellular carcinoma (HCC) which is highly metastatic. As most of cannabinoids have shown anticancer effect against different cell lines in a number of reports, a biological investigation of two cannabinoids, CB65 (CB2 receptor agonist) and ACEA (CB1 receptor agonist) was carried out in this study.

Objective: In an attempt to find natural products as a new solution of cancer, this study was designed to investigate the potential antitumoral and anti-invasive activity of cannabinoids on HepG2 cells and the possible roles of matrix metalloproteinase-2 (MMP-2) and MMP-9 in its action.

Materials and methods: The researchers examined the effect of various concentrations of CB65 (CB2 receptor agonist) and ACEA (CB1 receptor agonist), on the cell proliferation, viability, and invasion as well as expression of MMP-2 and MMP-9 in HepG2 cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assay, matrigel invasion assay, and western blotting method.

Results: The results revealed that both cannabinoids reduce cell viability, cell invasion as well as MMP-2 and MMP-9 expression in higher dose of 20?nM. Furthermore, higher concentrations of examined cannabinoids were more effective.

Discussion: These data suggest ACEA and CB65 as an option for novel treatment of hepatocellular cancer.

Conclusion: Our findings may contribute to design of new therapeutic strategies for the management of HCC.     

The potential of Beclin 1 as a therapeutic target for the treatment of breast cancer

Introduction: Beclin 1 plays a crucial role in autophagy via the Beclin 1 interactome, and is involved in various biological processes such as protein sorting, chemokinesis, and cell death. Via these biologic functions, Beclin 1 contributes to both tumor suppression and tumor progression.

Areas covered: Beclin 1 plays a key biologic function on cell homeostasis and affects tumorigenesis. In this review, detailing up-to-date knowledge on the tumorigenic role of Beclin 1, its implication in breast cancer, and its utility as a breast cancer-specific drug target is discussed.

Expert opinion: Because Beclin 1 is expressed in breast cancer cells, Beclin 1 could be a unique, effective drug target for the prevention and treatment of breast cancer. However, the expression of Beclin 1 varies according to cancer molecular subtypes, and Beclin 1 is involved in both breast cancer suppression and tumor progression; therefore, the decision of using a Beclin 1 inducer or inhibitor should be made based on breast cancer stage and subtype.     

Smilax glabra Roxb targets Aktp-Thr308 and inhibits Akt-mediated signaling pathways in SGC7901 cells

Background: Smilax glabra Roxb (SGR) as a novel anti-tumor agent has been paid attention in several types of cancer cells. However, the effect of SGR on SGC7901 cells has not been investigated.

Purpose: We investigate the effect and potential mechanisms of SGR on SGC7901 cells in this study.

Methods: Three kinds of gastric cancer cell lines (BGC823, SGC7901 and MKN45) and one kind of human embryonic kidney cell line (HEK293) were exposed to varying concentrations of SRG. Then, we observed the effect of SRG on these cell lines and the changes on proliferation, invasion and apoptosis. Finally, we detected the signaling pathway in which SGR may involve.

Results: SGR effectively suppressed the proliferation of SGC7901 cell lines by inhibiting the phosphorylation of Akt (Thr308). Moreover, we found SGR could significantly induce SGC7901 cell lines apoptosis by inhibiting Akt^p-Thr308/Bad pathway and inhibit its migration and invasion partly by inhibiting Akt^p-Thr308/MMPs pathway.

Discussion: SGR could effectively suppress the proliferation and invasion of SGC7901 cell lines by inhibiting the phosphorylation of Akt (Thr308) and its downstream relative pathways.

Conclusion: SGR could effectively suppress the phosphorylation of Akt (Thr308) and then inhibit the proliferation and invasion of SGC7901 cell and enhance its apoptosis through Akt-mediated signaling pathways.     

Fangchinoline as a kinase inhibitor targets FAK and suppresses FAK-mediated signaling pathway in A549

Background: Fangchinoline as a novel anti-tumor agent has been paid attention in several types of cancers cells except lung cancer. Here we have investigated the effect of fangchinoline on A549 cells and its underlying mechanism.

Purpose: The purpose of this work was to study the effect of fangchinoline on A549 cells.

Methods: Four lung cancer cell lines (A549, NCI-H292, NCI-H446, and NCI-H460) were exposed to varying concentrations (10–40?μmol/l) of fangchinoline to observe the effect of fangchinoline on the four lung cancer cell lines and to observe the changes of the lung cancer cell on proliferation, apoptosis, and invasion.

Results: Fangchinoline effectively suppressed proliferation and invasion of A549 cell line but not NCI-H292, NCI-H446, and NCI-H460 cell lines by inhibiting the phosphorylation of FAK (Tyr397) and its downstream pathways, due to the significant differences of Fak expression between A549 and the other three cell lines. And all FAK-paxillin/MMP2/MMP9 pathway, FAK-Akt pathway, and FAK-MEK-ERK1/2 pathway could be inhibited by fangchinoline.

Discussion: Fangchinoline effectively suppressed proliferation and invasion of A549 cell line by inhibiting the phosphorylation of FAK (Tyr397) and its downstream pathways.

Conclusion: Fangchinoline could inhibit the phosphorylation of FAK^p-Tyr397, at least partially. Fangchinoline as a kinase inhibitor targets FAK and suppresses FAK-mediated signaling pathway and inhibits the growth and the invasion in tumor cells which highly expressed FAK such as A549 cell line.     

Therapeutic targeting of B7-H1 in breast cancer

Introduction: Breast cancer is the most common form of malignancy occurring in women worldwide. B7-H1 is a co-inhibitory molecule expressed by several types of tumors, including breast cancer. The aberrant expression of B7-H1 in breast cancer cells has been determined, its role in recruiting regulatory T cells into the tumor microenvironment has been elucidated and a strong link to B7-H1 induction in highly proliferative breast cancer has been provided. It has also been demonstrated that doxorubicin, a drug commonly used for breast cancer treatment, downregulates the cell surface expression of B7-H1 and upregulates its nuclear expression, which therefore suggests an anti-apoptotic role of B7-H1 in breast cancer.

Areas covered: This review illustrates the various factors involved in the induction of B7-H1 and its role in immune evasion and chemoresistance. It also provides potential therapeutic strategies for targeting B7-H1 in breast cancer.

Expert opinion: B7-H1 should be considered as a potential therapeutic target for breast cancer. Indeed, there is increasing evidence for the potential efficacy of B7-H1 blockade in the prevention of immune evasion by cancer cells. Additionally, B7-H1 targeting can be used in conjunction with other therapeutic modalities for improved efficacy and reduced toxicity. We expect that B7-H1 blockade in combination with other therapeutics will be a prime therapeutic strategy in the future.     

RhoGDI2 as a therapeutic target in cancer

Importance of the field: Rho GDP dissociation inhibitor 2 (RhoGDI2) has been identified as a regulator of Rho GTPases that play important roles in the development of numerous aspects of the malignant phenotype, including cell cycle progression, resistance to apoptotic stimuli, neovascularization, tumor cell motility, invasiveness, and metastasis. Although RhoGDI2 has been known to be expressed only in hematopoietic tissues, recent studies suggest that this protein is also aberrantly expressed in several human cancers and contributes to aggressive phenotypes, such as invasion and metastasis. Hence, RhoGDI2 appears to be a target of interest for therapeutic manipulation.

Areas covered in this review: Here, we summarize the role of RhoGDI2 in human cancers, specifically metastasis-related processes, and discuss its potential as a therapeutic target.

What the reader will gain: RhoGDI2 modulates the invasiveness and metastatic ability of cancer cells through regulation of Rac1 activity.

Take home message: RhoGDI2 may be a useful marker for tumor progression in human cancers, and interruption of the RhoGDI2-mediated cancer cell invasion and metastasis by an interfacial inhibitor may be a powerful therapeutic approach to cancer.     

Curcumin synergistically increases effects of β-interferon and retinoic acid on breast cancer cells in vitro and in vivo by up-regulation of GRIM-19 through STAT3-dependent and STAT3-independent pathways

Objective: The study aimed to investigate the effects of combination treatment of curcumin and β-interferon (IFN-β)/retinoic acid (RA) on breast cancer cells, including cell viability, apoptosis and migration, and to determine the mechanisms related to GRIM-19 through STAT3-dependent and STAT3-independent pathways.

Methods: The following groups were used for the in vitro experiment: control siRNA, GRIM-19 siRNA, IFN-β/RA and IFN-β/RA?+?curcumin. Cell viability is by the MTT method, cell apoptosis by flow cytometry and cell migration by wound healing experiment; GRIM-19, STAT3, survivin, Bcl-2, GADD153 and COX-2 expression was measured by Western blot. In vivo experiment, MCF-7 cells were subcutaneously injected into nude mice.

Results: GRIM-19 siRNA promoted MCF-7 cell proliferation and migration; inhibited cell apoptosis; and promoted the expression of STAT3, survivin, Bcl-2 and MMP-9. IFN-β/RA inhibited cell proliferation and migration; promoted cell apoptosis; up-regulated GRIM-19; and inhibited the expression of STAT3, survivin, Bcl-2 and MMP-9. Combination treatment of curcumin and IFN-β/RA had a stronger effect than that of the IFN-β/RA group. In addition, curcumin and IFN-β/RA combination inhibited the expression of COX-2 and up-regulated GADD153.

Conclusion: Curcumin synergistically increases the effects of IFN-β/RA on breast cancer cells. The mechanism may be related to the up-regulation of GRIM-19 through STAT3-dependent and STAT3-independent pathways.     

Status of research on matrix metalloproteinases (MMPs) in India

Introduction: MMPs are extracellular matrix (ECM)-degrading enzymes that play a crucial role in embryogenesis, tissue remodeling, inflammation and angiogenesis. MMP-2 and -9 (also called type 2 and type 4 collagenase, or gelatinase A and B) are the key molecules that control invasion, tumor growth and metastasis. Tissue inhibitor of matrix metalloproteinase (TIMP) -2 and -1 are specific inhibitors of MMP-2 and MMP-9 respectively, and play a crucial role in regulation of MMP-2 and -9 activation, during pathophysiological processes. MMPs can specifically degrade native gelatin, collagens, fibronectin, ectactin and elastin. MMP-2 and -9 are overexpressed in almost all types of cancers, and so act as important therapeutic targets.

Areas covered: The status of MMP research in India from 1998 to 2010. In this review, the authors cover the role of matrix metalloproteinase inhibitors in cancer therapy.

Expert opinion: As compared with other parts of the world, Indian scientists have not generated a significant number of specific MMP inhibitors for the treatment of cancer, or other diseases. MMPs and membrane type (MT)-MMPs are potentially important therapeutic targets in many diseases, including cancers, therefore, designing specific inhibitors from natural products or through synthetic routes, is crucial.     

mPEG-b-PCL/TPGS mixed micelles for delivery of resveratrol in overcoming resistant breast cancer

Objective: Drug resistance remains a major challenge for effective breast cancer chemotherapy. Resveratrol (Res) is a promising candidate for overcoming cancer chemoresistance, but it has low bioavailability due to poor absorption, and ready metabolism limits its application. This study aims to develop a Res-loaded mixed micelle system to be effective on drug resistance of breast cancer cells.

Methods: A mixed micelle system made of methoxy poly (ethylene glycol)-b-polycaprolactone (mPEG-PCL) and d-α-Tocopherol polyethylene glycol succinate was prepared and Res was encapsulated to form Res-loaded mixed micelles. Furthermore, the antitumor activity against doxorubicin (Dox)-resistant breast cancer MCF-7/ADR cells was studied and the possible mechanism was elucidated.

Results: The mixed micellar formulation increased drug uptake efficiency of Res by Dox-resistant breast cancer MCF-7/ADR cells, and induced higher rates of apoptotic cell death, as assessed by the accumulation of Sub G1 phases of cell cycle, nucleus staining and Annexin-FITC/propidium iodide assay. Moreover, Res-loaded mixed micelles also markedly enhanced Dox-induced cytotoxicity in MCF-7/ADR cells and increased the cellular accumulation of Dox by downregulating the expression of P-glycoprotein (P-gp) and inhibiting the activity thereof.

Conclusion: The cumulative evidence indicates that Res-loaded mixed micelles hold significant promise for the treatment of drug-resistant breast cancer.     

Astragaloside IV inhibits breast cancer cell invasion by suppressing Vav3 mediated Rac1/MAPK signaling

BackgroundAstragaloside IV (AS-IV), the major active triterpenoid in Radix Astragali, has shown anti-tumorigenic properties in certain cancers; however, its role in breast cancer remains unclear. The present study investigated the effects of AS-IV on breast cancer in vitro and in vivo and examined the underlying mechanisms.MethodsThe effects of AS-IV on MDA-MB-231 cell proliferation, migration, invasion and metastasis were investigated by MTT and Transwell assays, and western blotting. In addition, an orthotopic mouse tumor model was established for in vivo experiments.ResultsAS-IV inhibited the viability and invasive potential of MDA-MB-231 breast cancer cells, suppressed the activation of the mitogen activated protein kinase (MAPK) family members ERK1/2 and JNK, and downregulated matrix metalloproteases (MMP)-2 and -9. The effects of AS-IV were mediated by the downregulation of Vav3, a guanine nucleotide exchange factor, leading to decreased levels of activated Rac1, a Rho family GTPase. Vav3 overexpression promoted cell proliferation and invasion in vitro, whereas Vav3 silencing had the opposite effects. AS-IV suppressed orthotopic breast tumor growth and metastasis to the lungs, whereas ectopic expression of Vav3 reversed the inhibitory effect of AS-IV on cell viability, invasiveness, MAPK signaling and MMP expression.ConclusionThe present results provide a mechanistic explanation for the antitumor effects of AS-IV and suggest its potential in the treatment of metastatic breast cancer.     

Inhibition of invasion and metastasis of human liver cancer HCCLM3 cells by portulacerebroside A

Abstract

Context: Portulacerebroside A (PCA) is a novel cerebroside compound isolated from Portulaca oleracea L. (Portulacaceae), an edible and medicinal plant distributed in the temperate and tropical zones worldwide.

Objective: This study investigates the effects of PCA in human liver cancer HCCLM3 cells on metastasis and invasion.

Materials and methods: After the cells were treated with PCA (2.5, 5, and 10?μg/ml) for 6, 12, 24, or 48?h, adhesion, transwell invasion, and scratch tests were conducted and cell functions were evaluated. Western blot and FQ-RT-PCR assays explored the mechanism of PCA-inhibited invasion and metastasis in the cells.

Results: The adhesion rate of the cells was suppressed at 0.5?h (79.4?±?1.0, 68.7?±?1.3, and 58.1?±?1.3%, versus 100?±?1.5% in the control), 1?h (78.2?±?1.2, 70.9?±?1.6, and 55.4?±?1.9%, versus 100?±?1.2% in the control), and 1.5?h (71.6?±?1.1, 62.3?±?0.9, and 50.4?±?0.9%, versus 100?±?1.1% in the control). The 24?h invasion ability was decreased (356.6?±?11.2, 204.0?±?17.6, and 113.0?±?9.5%, versus 443.6?±?15.4% in the control). The migration capability was also restrained by PCA for 24?h (324.8?±?25.4, 250.4?±?21.0, and 126.3?±?10.1, versus 381.6?±?30.6 in the control) and 48?h (470.3?±?34.3, 404.0?±?19.7, and 201.0?±?15.4, versus 752.0?±?63.6 in the control). There was an increase in the mRNA and protein expression levels of TIMP-2 and nm23-H1, inhibition in the mRNA expression of MTA1, MMP-2, and MMP-9, and suppression in the protein expression of MTA1, RhoA, Rac1/Cdc42, MMP-2, but not RhoC and MMP-9.

Conclusion: PCA suppresses the invasion and metastasis of HCCLM3 cells possibly by modulation of the mRNA and protein expression of related parameters. This is the first study to reveal a new potential therapeutic application of PCA in antimetastatic therapy for liver cancer.     

Lapatinib for breast cancer: a review of the current literature

Importance of the field: The identification of HER-2 expression as a predictive and prognostic marker revolutionized breast cancer. Trastuzumab, a humanized mAb, improves survival in both early and advanced HER-2 overexpressing breast cancer. However, many cancers either do not respond or develop resistance to this agent. Lapatinib is an oral tyrosine kinase inhibitor which has both HER-1 and -2 activities and has been licensed for use in recurrent breast cancer that overexpresses HER-2. Studies of lapatinib in early breast cancer are ongoing.

Areas covered in this review: A PubMed search was conducted using ‘lapatinib’ and ‘breast cancer’ as the key words. All published works up to July 2010 were reviewed. A manual review of abstracts presented at the ASCO Annual meeting and the San Antonio Breast Cancer Symposium was conducted for the last 2 years. In this review, we summarize the current knowledge of lapatinib and pose questions which need to be addressed as we further expand our knowledge of the HER-2 subtypes of breast cancer.

What the reader will gain: The reader will gain an up-to-date and comprehensive review of the current literature as it pertains to the safety and efficacy of lapatinib in the treatment of breast cancer.

Take home message: Lapatinib has provided an alternative for the treatment of advanced HER-2 overexpressing breast cancer and is currently being assessed in early disease.