Annexin-I expression modulates drug resistance in tumor cells

The role of ANXA1 in the tumor microenvironment

Annexin A1 (ANXA1) is widely expressed in a variety of body tissues and cells and is also involved in tumor development through multiple pathways. The invasion, metastasis, and immune escape of tumor cells depend on the interaction between tumor cells and their surrounding environment. Research shows that ANXA1 can act on a variety of cells in the tumor microenvironment (TME), and subsequently affect the proliferation, invasion and metastasis of tumors. This article describes the role of ANXA1 in the various components of the tumor microenvironment and its mechanism of action, as well as the existing clinical treatment measures related to ANXA1. These findings provide insight for the further design of strategies targeting ANXA1 for the diagnosis and treatment of malignant tumors.

Plasma membrane repair empowers the necrotic survivors as innate immune modulators

The plasma membrane is crucial to the survival of animal cells, and damage to it can be lethal, often resulting in necrosis. However, cells possess multiple mechanisms for repairing the membrane, which allows them to maintain their integrity to some extent, and sometimes even survive. Interestingly, cells that survive a near-necrosis experience can recognize sub-lethal membrane damage and use it as a signal to secrete chemokines and cytokines, which activate the immune response. This review will present evidence of necrotic cell survival in both in vitro and in vivo systems, including in C. elegans, mouse models, and humans. We will also summarize the various membrane repair mechanisms cells use to maintain membrane integrity. Finally, we will propose a mathematical model to illustrate how near-death experiences can transform dying cells into innate immune modulators for their microenvironment. By utilizing their membrane repair activity, the biological effects of cell death can extend beyond the mere elimination of the cells.

Label-Free Quantitative Proteomics Analysis of Adriamycin Selected Multidrug Resistant Human Lung Cancer Cells

The development of drug resistance in lung cancer is a major clinical challenge, leading to a 5-year survival rate of only 18%. Therefore, unravelling the mechanisms of drug resistance and developing novel therapeutic strategies is of crucial importance. This study systematically explores the novel biomarkers of drug resistance using a lung cancer model (DLKP) with a series of drug-resistant variants. In-depth label-free quantitative mass spectrometry-based proteomics and gene ontology analysis shows that parental DLKP cells significantly differ from drug-resistant variants, and the cellular proteome changes even among the drug-resistant subpopulations. Overall, ABC transporter proteins and lipid metabolism were determined to play a significant role in the formation of drug resistance in DKLP cells. A series of membrane-related proteins such as HMOX1, TMB1, EPHX2 and NEU1 were identified to be correlated with levels of drug resistance in the DLKP subpopulations. The study also showed enrichment in biological processes and molecular functions such as drug metabolism, cellular response to the drug and drug binding. In gene ontology analysis, 18 proteins were determined to be positively or negatively correlated with resistance levels. Overall, 34 proteins which potentially have a therapeutic and diagnostic value were identified.

A Cell-Based Systematic Review on the Role of Annexin A1 in Triple-Negative Breast Cancers

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype that is often associated with a poorer prognosis and does not respond to hormonal therapy. Increasing evidence highlights the exploitability of Annexin A1 (AnxA1), a calcium dependent protein, as a precision medicine for TNBC. To systematically summarize the role of AnxA1 and its associated mechanisms in TNBC, we performed data mining using three main databases: PubMed, Scopus, and Ovid/Medline. The papers retrieved were based on two different sets of key words such as “Annexin A1” or “Lipocortin 1” and “Breast cancer” or “TNBC”. A total of 388 articles were identified, with 210 chosen for comprehensive screening and 13 papers that met inclusion criteria were included. Current evidence from cell culture studies showed that AnxA1 expression is correlated with NF-κB, which promotes migration by activating ERK phosphorylation. AnxaA1 also activates TGF-β signaling which upregulates MMP-9 and miR196a expression to enhance epithelial-mesenchymal transition and migratory capacity of TNBC cells. AnxA1 can steer the macrophage polarization toward the M2 phenotype to create a pro-tumor immune environment. Existing research suggests a potential role of AnxA1 in the metastasis and immune landscape of TNBC tumors. Preclinical and clinical experiments are warranted to investigate the feasibility and effectiveness of targeting AnxA1 in TNBC.

Curcumin encapsulation in functional PLGA nanoparticles: A promising strategy for cancer therapies

Nanoparticles have emerged as promising drug delivery systems for the treatment of several diseases. Novel cancer therapies have exploited these particles as alternative adjuvant therapies to overcome the traditional limitations of radio and chemotherapy. Curcumin is a natural bioactive compound found in turmeric, that has been reported to show anticancer activity against several types of tumors. Despite some biological limitations regarding its absorption in the human body, curcumin encapsulation in poly(lactic-co-glycolic acid) (PLGA), a non-toxic, biodegradable and biocompatible polymer, represents an effective strategy to deliver a drug to a tumor site. Furthermore, PLGA nanoparticles can be engineered with targeting moieties to reach specific cancer cells, thus enhancing the antitumor effects of curcumin. We herein aim to bring an up-to-date summary of the recently developed strategies for curcumin delivery to different types of cancer cells through encapsulation in PLGA nanoparticles, correlating their effects with those of curcumin on the biological capabilities acquired by cancer cells (cancer hallmarks). We discuss the targeting strategies proposed for advanced curcumin delivery and the respective improvements achieved for each cancer cell analyzed, in addition to exploring the encapsulation techniques employed. The conjugation of correct encapsulation techniques with tumor-oriented targeting design can result in curcumin-loaded PLGA nanoparticles that can successfully integrate the elaborate network of development of alternative cancer treatments along with traditional ones. Finally, the current challenges and future demands to launch these nanoparticles in oncology are comprehensively examined.

Annexin A1 as a Regulator of Immune Response in Cancer

Annexin A1 is a 37 kDa phospholipid-binding protein that is expressed in many tissues and cell types, including leukocytes, lymphocytes and epithelial cells. Although Annexin A1 has been extensively studied for its anti-inflammatory activity, it has been shown that, in the cancer context, its activity switches from anti-inflammatory to pro-inflammatory. Remarkably, Annexin A1 shows pro-invasive and pro-tumoral properties in several cancers either by eliciting autocrine signaling in cancer cells or by inducing a favorable tumor microenvironment. Indeed, the signaling of the N-terminal peptide of AnxA1 has been described to promote the switching of macrophages to the pro-tumoral M2 phenotype. Moreover, AnxA1 has been described to prevent the induction of antigen-specific cytotoxic T cell response and to play an essential role in the induction of regulatory T lymphocytes. In this way, Annexin A1 inhibits the anti-tumor immunity and supports the formation of an immunosuppressed tumor microenvironment that promotes tumor growth and metastasis. For these reasons, in this review we aim to describe the role of Annexin A1 in the establishment of the tumor microenvironment, focusing on the immunosuppressive and immunomodulatory activities of Annexin A1 and on its interaction with the epidermal growth factor receptor.

Decreased Annexin A1 expression enhances sensitivity to docetaxel, cisplatin and 5-fluorouracil combination induction chemotherapy in oral squamous cell carcinoma

BACKGROUND

Annexin A1, a member of the Annexin superfamily, has been shown to play a vital role in a broad range of molecular and cellular processes. This study aims to explore the relationship between the Annexin A1 expression and the clinical response to cisplatin, docetaxel and 5-fluorouracil (TPF) as induction chemotherapy in patients with oral squamous cell carcinoma (OSCC).

METHODS

This study recruited two hundred thirty-two patients from a III/IVA OSCC trial. Immunohistochemistry was used to assess the level of Annexin A1 expression. Overexpression and knockdown methods in HB96, HN4 and CAL27 cell lines were used to assess the role of Annexin A1 in the neoplastic cellular response to chemotherapy.

RESULTS

We found that reduced expression of Annexin A1 conferred a prognostic benefit from induction chemotherapy based on the TPF drug combination in patients with moderately/poorly differentiated disease. Using an in vitro model, we found that low Annexin A1 enhanced cellular proliferation by activating the EGFR/AKT signalling pathway and inhibiting p27 expression. Furthermore, low Annexin A1 initiated a significant decrease in cell viability after treatment with TPF agents. In addition, downregulation of Annexin A1 promoted apoptosis induced by docetaxel, cisplatin and 5-fluorouracil, and upregulation of Annexin A1 inhibited apoptosis.

CONCLUSION

Annexin A1 may be of prognostic value in patients with locally advanced OSCC who are managed with TPF chemotherapy, as low Annexin A1 promotes chemosensitivity to TPF chemotherapy in oral cancer cells via enhanced caspase-dependent apoptosis.

Plasma membrane integrity in health and disease: significance and therapeutic potential

Maintenance of plasma membrane integrity is essential for normal cell viability and function. Thus, robust membrane repair mechanisms have evolved to counteract the eminent threat of a torn plasma membrane. Different repair mechanisms and the bio-physical parameters required for efficient repair are now emerging from different research groups. However, less is known about when these mechanisms come into play. This review focuses on the existence of membrane disruptions and repair mechanisms in both physiological and pathological conditions, and across multiple cell types, albeit to different degrees. Fundamentally, irrespective of the source of membrane disruption, aberrant calcium influx is the common stimulus that activates the membrane repair response. Inadequate repair responses can tip the balance between physiology and pathology, highlighting the significance of plasma membrane integrity. For example, an over-activated repair response can promote cancer invasion, while the inability to efficiently repair membrane can drive neurodegeneration and muscular dystrophies. The interdisciplinary view explored here emphasises the widespread potential of targeting plasma membrane repair mechanisms for therapeutic purposes.

Annexin A1: A Bane or a Boon in Cancer? A Systematic Review

Annexin A1 has been extensively investigated as an anti-inflammatory protein, but its role in different types of cancer has not been consolidated in a single systematic review to date. Thus, the aim of this paper is to systematically review and critically analyse 18 studies (in-vivo and in-vitro) to consolidate, in a concerted manner, all the information on differential expression of Annexin A1 in different types of cancer and the role this protein plays in tumorigenesis. Pubmed, Scopus, Web of Science, and ScienceDirect were used for the literature search and the keywords used are “annexin A1,” “lipocortin 1,” “cancer,” “malignancy,” “neoplasm,” “neoplasia,” and “tumor.” A total of 1128 articles were retrieved by implementing a standard search strategy subjected to meticulous screening processes and 442 articles were selected for full article screening. A total of 18 articles that adhered to the inclusion criteria were included in the systematic review and these articles possessed low to moderate bias. These studies showed a strong correlation between Annexin A1 expression and cancer progression via modulation of various cancer-associated pathways. Differential expression of Annexin A1 is shown to play a role in cellular proliferation, metastasis, lymphatic invasion, and development of resistance to anti-cancer treatment. Meta-analysis in the future may provide a statistically driven association between Annexin A1 expression and malignancy progression.

DCST1-AS1 Promotes TGF-β-Induced Epithelial-Mesenchymal Transition and Enhances Chemoresistance in Triple-Negative Breast Cancer Cells via ANXA1

Triple-negative breast cancer (TNBC) is a highly metastatic breast cancer subtype, and the primary systemic treatment strategy involves conventional chemotherapy. DC-STAMP domain containing 1-antisense 1 (DCST1-AS1) is a long non-coding RNA that promotes TNBC migration and invasion. Studying the role of DCST1-AS1 in promoting epithelial–mesenchymal transition (EMT) and chemoresistance will provide a new strategy for TNBC therapy. In the present study, we found that DCST1-AS1 regulates the expression or secretion of EMT-related proteins E-cadherin, snail family zinc finger 1 (SNAI1), vimentin, matrix metallopeptidase 2 (MMP2), and matrix metallopeptidase 9 (MMP9). Interference with DCST1-AS1 impaired TGF-β-induced TNBC cell invasion and migration. DCST1-AS1 directly binds to ANXA1 in BT-549 cells and affects the expression of ANXA1. DCST1-AS1 enhances TGF-β/Smad signaling in BT-549 cells through ANXA1 to promote EMT. The combination of DCST1-AS1 and ANXA1 also contributes to enhancement of the resistance of BT-549 cells to doxorubicin and paclitaxel. In conclusion, DCST1-AS1 promotes TGF-β-induced EMT and enhances chemoresistance in TNBC cells through ANXA1, and therefore represents a potentially promising target for metastatic breast cancer therapy.

Advancements of Annexin A1 in inflammation and tumorigenesis

Annexin A1 is a Ca²⁺-dependent phospholipid binding protein involved in a variety of pathophysiological processes. Accumulated evidence has indicated that Annexin A1 has important functions in cell proliferation, apoptosis, differentiation, metastasis, and inflammatory response. Moreover, the abnormal expression of Annexin A1 is closely related to the occurrence and development of tumors. In this review article, we focus on the structure and function of Annexin A1 protein, especially the recent evidence of Annexin A1 in the pathophysiological role of inflammatory and cancer. This summary will be very important for further investigation of the pathophysiological role of Annexin A1 and for the development of novel therapeutics of inflammatory and cancer based on targeting Annexin A1 protein.

Expression of genes and proteins of multidrug resistance in gastric cancer cells treated with resveratrol

Multidrug resistance (MDR) is a notable problem in the use of chemotherapy. Therefore, studies aimed at identifying substances capable of overcoming resistance of cancer cells are required. Examples of these compounds are polyphenols, including resveratrol, that exert a range of various biological activities. The aim of the present study was to demonstrate the effect of 3,5,4'-trihydroxy-trans-stilbene (resveratrol) on the expression of ATP binding cassette subfamily B member 1, Annexin A1 (ANXA1) and thioredoxin (TXN) genes, and the proteins encoded by these genes, which are associated with MDR. The experiments were performed in human gastric cancer cell lines EPG85-257RDB (RDB) and EPG85-257RNOV (RNOV), which are resistant to daunorubicin and mitoxantrone, respectively, in addition to EPG85-257P (control), which is sensitive to cytostatic drugs. Cells were treated with 30 or 50 µM resveratrol for 72 h and changes in the expression levels of the genes were analysed with the use of a reverse transcription-quantitative polymerase chain reaction. The cellular levels of P-glycoprotein (P-gp), ANXA1 and TXN were evaluated using immunofluorescence and western blot analysis. Resveratrol in both concentrations has been shown to have a statistically significant influence on expression of the mentioned genes, compared with untreated cells. In RDB cells, resveratrol reduced the expression level of all analyzed genes, compared with untreated cells. Similar results at the protein level were obtained for P-gp and TXN. In turn, in the RNOV cell line, resveratrol reduced TXN expression at mRNA and protein levels, compared with untreated cells. The results of the present study indicate that resveratrol may reduce the resistance of cancer cells by affecting the expression of a number of the genes and proteins associated with MDR.

Downregulation of annexin A3 inhibits tumor metastasis and decreases drug resistance in breast cancer

Annexin A3 (ANXA3) is dysregulated and plays an important role in various cancers. However, the role of ANXA3 in breast cancer is still unclear. Here, we observed that the expression level of ANXA3 was significantly upregulated in breast cancer tissues. ANXA3 knockdown inhibited cell invasion but promoted cell proliferation in both in vitro and in vivo assays. Furthermore, we found that ANXA3 knockdown inhibited the NFκB pathway via upregulating IκBα, resulting in mesenchymal–epithelial transition (MET) and a heterogeneity change of breast cancer stem cells (BCSCs). In addition, we demonstrated that ANXA3 knockdown increased the sensitivity of breast cancer cells to doxorubicin by increasing the drug uptake. The combination of ANXA3 knockdown and doxorubicin treatment simultaneously inhibited tumor growth and metastasis in vivo. This study described the role and mechanisms of ANXA3 in regulating BCSCs and breast cancer growth and metastasis, indicating that downregulating ANXA3 together with chemotherapy might be a novel therapeutic strategy for treating breast cancer.

Effects of Catechins and Their Related Compounds on Cellular Accumulation and Efflux Transport of Mitoxantrone in Caco-2 Cell Monolayers

The ability of catechins and their related compounds to inhibit breast cancer resistance protein (BCRP) function in Caco-2 cell monolayers was investigated with mitoxantrone as a BCRP substrate. The gallate or pyrogallol moiety on the catechin structure seemed to promote increased cellular accumulation and inhibit efflux transport of mitoxantrone. The ability of gallate catechins such as (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin gallate (ECG) to increase cellular accumulation and inhibit efflux transport of mitoxantrone was greater than that of nongallate catechins. Gallic acid octyl ester (GAO) also increased intracellular mitoxantrone accumulation. Experiments using GAO derivatives indicated that the gallate moiety required the presence of a long carbon chain for BCRP inhibition. Cellular accumulation and reduced efflux transport of mitoxantrone were greater with epigallocatechin 3-(3″-O-butyl) gallate than with EGCG. EGCG inhibition of BCRP seemed to be restricted by hydrophobicity. The co-administration of catechins, particularly EGCG and related compounds, with greater hydrophobicity may increase the therapeutic activities of BCRP substrates such as mitoxantrone.

Annexin A1 is involved in resistance to 5-FU in colon cancer cells

Resistance to 5-fluorouracil (5‑FU), a key drug in the treatment of colorectal cancer, is one of the major reasons for poor patient prognosis during cancer treatment. Annexin A1 (ANXA1) is a calcium‑dependent phospholipid‑linked protein that is associated with drug resistance, anti‑inflammatory effects, regulation of cellular differentiation, proliferation and apoptosis. Although there have been several studies investigating ANXA1 expression in drug resistant cells, the role of ANXA1 is yet to be fully understood. We therefore, in this study, generated SW480 cells resistant to 5‑FU (SW480/5‑FU) to evaluate ANXA1 expression. When compared to the control cells, ANXA1 expression was significantly induced in the SW480/5‑FU cells. We then revealed the role of ANXA1 expression in 5‑FU resistance by using overexpression and knockdown methods in colon cancer cells. Overexpression of ANXA1 induced a significant increase of cell viability to 5‑FU, whereas ANXA1 knockdown induced a significant decrease of cell viability to 5‑FU. Further experiments revealed that ANXA1 expression was induced by hypoxia in colon cancer cells. These results suggest that ANXA1 expression may play a critical role in 5‑FU resistance and may be induced by hypoxia during cancer progression. Our results provide a possible strategy to overcome 5‑FU resistance by modulating ANXA1 expression.

Proteomic analysis on zoxamide-induced sensitivity changes in Phytophthora cactorum

Zoxamide is an important fungicide for oomycete disease management. In this study, we established the baseline sensitivity of Phytophthora cactorum to zoxamide and assessed the risk of developing resistance to zoxamide using ultraviolet irradiation and fungicide taming methods. All 73 studied isolates were sensitive to zoxamide, with effective concentrations for 50% inhibition of mycelial growth ranging from 0.04 to 0.29 mg/L and mean of 0.15 mg/L. Stable zoxamide-resistant mutants of P. cactorum were not obtained from four arbitrarily selected isolates by either treating mycelial cultures with ultraviolet irradiation or adapting mycelial cultures to the addition of increasing zoxamide concentrations. However, the sensitivity of the isolates to zoxamide could be easily reduced by successive zoxamide treatments. In addition to displaying decreased sensitivity to zoxamide, these isolates also showed decreased sensitivity to the fungicides flumorph and cymoxanil. Proteomic analysis indicated that some proteins involved in antioxidant detoxification, ATP-dependent multidrug resistance, and anti-apoptosis activity, are likely responsible for the induced decrease in the sensitivity of P. cactorum to zoxamide compared to controls. Further semi-quantitative PCR analysis demonstrated that the gene expression profiles of most of above proteins were consistent with the proteomic analysis. Based on the above results, P. cactorum shows low resistance risk to zoxamide; however, the fungicidal effect of zoxamide might be decreased due to induced resistance when this fungicide is continuously applied.

Upregulated Annexin A1 promotes cellular invasion in triple-negative breast cancer

Annexin A1 (ANXA1) is a calcium-dependent phospholipid-linked protein, involved in anti-inflammatory effects, regulation of cellular differentiation, proliferation and apoptosis. While many studies have investigated the ANXA1 expression in various tumor types, the role of ANXA1 is not fully understood. Therefore, in the present study, we evaluated the ANXA1 expression in 211 breast cancer patients and compared the levels with clinicopathological factors. ANXA1 was positively expressed in 31 (14.7%) of the 211 cases in our cohort, and these positive cases were associated with triple-negative breast cancer (TNBC) (P=0.007) and venous invasion (P=0.028). The in vitro cell experiment found that the MDA-MB-231 cell line, which is a TNBC cell line, highly expressed ANXA1. Using this cell line, the functional role of ANXA1 in breast cancer was revealed and the knockdown of ANXA1 by specific siRNA demonstrated a significant reduction in cellular invasion. Further experiments indicated that ANXA1 was induced by hypoxia with hypoxia-inducible factor-1α induction. These results suggested that ANXA1, which enhanced breast cancer invasion and metastasis under hypoxia, were significantly associated with the worst patient outcome. This is particularly noted in TNBC, the group of breast cancer with the worst outcome for which new therapeutic implications are required.

Comprehensive proteome quantification reveals NgBR as a new regulator for epithelial-mesenchymal transition of breast tumor cells

Nogo-B receptor (NgBR) is a type I receptor and specifically binds to ligand Nogo-B. Our previous work has shown that NgBR is highly expressed in human breast invasive ductal carcinoma. Here, comprehensive proteome quantification was performed to examine the alteration of protein expression profile in MDA-MB-231 breast tumor cells after knocking down NgBR using lentivirus-mediated shRNA approach. Among a total of 1771 proteins feasibly quantified, 994 proteins were quantified in two biological replicates with RSD <50%. There are 122 proteins significantly down-regulated in NgBR knockdown MDA-MB-231 breast tumor cells, such as vimentin and S100A4, well-known markers for mesenchymal cells, and CD44, a stemness indicator. The decrease of vimentin, S100A4 and CD44 protein expression levels was further confirmed by Western blot analysis. MDA-MB-231 cells are typical breast invasive ductal carcinoma cells showing mesenchymal phenotype. Cell morphology analysis demonstrates NgBR knockdown in MDA-MB-231 cells results in reversibility of epithelial-mesenchymal transition (EMT), which is one of the major mechanisms involved in breast cancer metastasis. Furthermore, we demonstrated that NgBR knockdown in MCF-7 cells significantly prevented the TGF-β-induced EMT process as determined by the morphology change, and staining of E-cadherin intercellular junction as well as the decreased expression of vimentin.

BIOLOGICAL SIGNIFICANCE

Our previous publication showed that NgBR is highly expressed in human breast invasive ductal carcinoma. However, the roles of NgBR and NgBR-mediated signaling pathway in breast tumor cells are still unclear. Here, we not only demonstrated that the quantitative proteomics analysis is a powerful tool to investigate the global biological function of NgBR, but also revealed that NgBR is involved in the transition of breast epithelial cells to mesenchymal stem cells, which is one of the major mechanisms involved in breast cancer metastasis. These findings provide new insights for understanding the roles of NgBR in regulating breast epithelial cell transform during the pathogenesis of breast cancer.

Annexin A1 in malignant tumors: current opinions and controversies

Annexin A1 is a 37 kDa calcium and phospholipid-binding protein that participates in several biological processes, such as inflammatory reactions, modulation of cell proliferation, regulation of cell death signaling, apoptosis, and, most importantly, tumor formation and development. Although annexin A1 has been implicated in the biology of various tumors, the findings are highly controversial and information regarding the underlying mechanism remains limited. Moreover, the mechanism by which annexin A1 participates in carcinogenesis and tumor progression is rather unclear. In the current study, we review the important biological functions of annexin A1 in different tumors. This work indicates that annexin A1 is a possible target for novel therapeutic intervention and that it is a potential biomarker for tumor diagnosis and screening.

Tissue proteomics using capillary isoelectric focusing-based multidimensional separations

The capabilities of capillary isoelectric focusing-based multidimensional separations for performing proteome analysis from minute samples create new opportunities in the pursuit of biomarker discovery using enriched and selected cell populations procured from tissue specimens. In this article, recent advances in online integration of capillary isoelectric focusing with nano-reversed phase liquid chromatography for achieving high-resolution peptide and protein separations prior to mass spectrometry analysis are reviewed, along with its potential application to tissue proteomics. These proteome technological advances combined with recently developed tissue microdissection techniques, provide powerful tools for those seeking to gain a greater understanding at the global level of the cellular machinery associated with human diseases such as cancer.

Binding and inhibition of drug transport proteins by heparin: a potential drug transporter modulator capable of reducing multidrug resistance in human cancer cells

A major problem in cancer treatment is the development of resistance to chemotherapeutic agents, multidrug resistance (MDR), associated with increased activity of transmembrane drug transporter proteins which impair cytotoxic treatment by rapidly removing the drugs from the targeted cells. Previously, it has been shown that heparin treatment of cancer patients undergoing chemotherapy increases survival. In order to determine whether heparin is capable reducing MDR and increasing the potency of chemotherapeutic drugs, the cytoxicity of a number of agents toward four cancer cell lines (a human enriched breast cancer stem cell line, two human breast cancer cell lines, MCF-7 and MDA-MB-231, and a human lung cancer cell line A549) was tested in the presence or absence of heparin. Results demonstrated that heparin increased the cytotoxicity of a range of chemotherapeutic agents. This effect was associated with the ability of heparin to bind to several of the drug transport proteins of the ABC and non ABC transporter systems. Among the ABC system, heparin treatment caused significant inhibition of the ATPase activity of ABCG2 and ABCC1, and of the efflux function observed as enhanced intracellular accumulation of specific substrates. Doxorubicin cytoxicity, which was enhanced by heparin treatment of MCF-7 cells, was found to be under the control of one of the major non-ABC transporter proteins, lung resistance protein (LRP). LRP was also shown to be a heparin-binding protein. These findings indicate that heparin has a potential role in the clinic as a drug transporter modulator to reduce multidrug resistance in cancer patients.

Fhit delocalizes annexin a4 from plasma membrane to cytosol and sensitizes lung cancer cells to paclitaxel

Fhit protein is lost or reduced in a large fraction of human tumors, and its restoration triggers apoptosis and suppresses tumor formation or progression in preclinical models. Here, we describe the identification of candidate Fhit-interacting proteins with cytosolic and plasma membrane localization. Among these, Annexin 4 (ANXA4) was validated by co-immunoprecipitation and confocal microscopy as a partner of this novel Fhit protein complex. Here we report that overexpression of Fhit prevents Annexin A4 translocation from cytosol to plasma membrane in A549 lung cancer cells treated with paclitaxel. Moreover, paclitaxel administration in combination with AdFHIT acts synergistically to increase the apoptotic rate of tumor cells both in vitro and in vivo experiments.

Potential role of Anxa1 in cancer

The annexins are a well-known, closely related, multigene superfamily of Ca2+-regulated, phospholipid-dependent, membrane-binding proteins. As a member of the annexins, Anxa1 participates in a variety of important biological processes, such as cellular transduction, membrane aggregation, inflammation, phagocytosis, proliferation, differentiation and apoptosis. Accumulated evidence has indicated that Anxa1 deregulations are associated with the development, invasion, metastasis, occurrence and drug resistance of cancers. The research evidence in recent years indicates that Anxa1 might specifically function either as a tumor suppressor or a tumor promoter candidate for certain cancers depending on the particular type of tumor cells/tissues. This article summarizes the associations between Anxa1 and malignant tumors, as well as potential action mechanisms. Anxa1 has the potential to be used in the future as a biomarker for the diagnosis, treatment and prognosis of certain tumors.

Identification of Annexin A1 interacting proteins in chronic myeloid leukemia KCL22 cells

In the present study, we used a functional proteomic approach to identify Annexin A1 (Anxa1) interacting proteins in the Philadelphia-positive KCL22 cell line. We focused on Anxa1 because it is one of the major proteins upregulated in imatinib-sensitive KCL22S cells versus imatinib-resistant KCL22R. Our proteomic strategy revealed 21 interactors. Bioinformatic analysis showed that most of these proteins are involved in cell death processes. Among the proteins identified, we studied the interaction of Anxa1 with two phosphatases, Shp1 and Shp2, which were recently identified as biomarkers of imatinib sensitivity in patients affected by chronic myeloid leukemia. Our data open new perspectives in the search for annexin-mediated signaling pathways and may shed light on mechanisms of resistance to imatinib that are unrelated to Bcr-Abl activity. All mass spectrometry data have been deposited in the ProteomeXchange with identifier PXD000030.

Low Annexin A1 expression predicts benefit from induction chemotherapy in oral cancer patients with moderate or poor pathologic differentiation grade

BACKGROUND

The benefit of induction chemotherapy in locally advanced oral squamous cell carcinoma (OSCC) remains to be clearly defined. Induction chemotherapy is likely to be effective for biologically distinct subgroups of patients and biomarker development might lead to identification of the patients whose tumors are to respond to a particular treatment. Annexin A1 may serve as a biomarker for responsiveness to induction chemotherapy. The aim of this study was to investigate Annexin A1 expression in pre-treatment biopsies from a cohort of OSCC patients treated with surgery and post-operative radiotherapy or docetaxel, cisplatin and 5-fluorouracil (TPF) induction chemotherapy followed by surgery and post-operative radiotherapy. Furthermore we sought to assess the utility of Annexin A1 as a prognostic or predictive biomarker.

METHODS

Immunohistochemical staining for Annexin A1 was performed in pre-treatment biopsies from 232 of 256 clinical stage III/IVA OSCC patients. Annexin A1 index was estimated as the proportion of tumor cells (low and high, <50% and ≥50% of stained cells, respectively) to Annexin A1 cellular membrane and cytoplasm staining.

RESULTS

There was a significant correlation between Annexin A1 expression and pathologic differentiation grade (P=0.015) in OSCC patients. The proportion of patients with low Annexin A1 expression was significantly higher amongst those with moderate/poorly differentiated tumor (78/167) compared to those with well differentiated tumor (18/65). Multivariate Cox model analysis showed clinical stage (P=0.001) and Annexin A1 expression (P=0.038) as independent prognostic risk factors. Furthermore, a low Annexin A1 expression level was predictive of longer disease-free survival (P=0.036, HR=0.620) and locoregional recurrence-free survival (P=0.031, HR=0.607) compared to high Annexin A1 expression. Patients with moderate/poorly differentiated tumor and low Annexin A1 expression benefited from TPF induction chemotherapy as measured by distant metastasis-free survival (P=0.048, HR=0.373) as well as overall survival (P=0.078, HR=0.410).

CONCLUSIONS

Annexin A1 can be used as a prognostic biomarker for OSCC. Patients with moderate/poorly differentiated OSCC and low Annexin A1 expression can benefit from the addition of TPF induction chemotherapy to surgery and post-operative radiotherapy. Annexin A1 expression can potentially be used as a predictive biomarker to select OSCC patients with moderate/poorly differentiated tumor who may benefit from TPF induction chemotherapy.

Increased expression of annexin I is associated with drug-resistance in nasopharyngeal carcinoma and other solid tumors

Adjuvant chemotherapy alongside radiotherapy is one of the effective therapies in nasopharyngeal carcinoma (NPC) treatment. However, the appearance of drug resistance is a major obstacle for anti-cancer chemotherapy and often causes failure of the chemotherapy. In this study, a drug-resistant gene annexin I (ANX-I) was identified by comparing differentially expressed proteins between a cisplatin (CDDP)-resistant NPC cell line CNE2-CDDP and parental CNE2 cells using 2-DE. When ANX-I was transfected into CNE2 cells, the CDDP resistance of CNE2 cells was dramatically increased. The drug-resistant ability of ANX-I was demonstrated by both in vitro and in vivo assays. The association of ANX-I expression with clinical features was also investigated. Increased expression of ANX-I was significantly associated with disease relapse in NPC (p<0.05). In breast and gastric cancer, increased expression of ANX-I was significantly associated with drug resistance (p<0.001) and poor prognosis (p<0.001), respectively. Taken together, our findings suggest that ANX-I plays an important role in drug resistance.

Secretion of annexin A3 from ovarian cancer cells and its association with platinum resistance in ovarian cancer patients

Early detection of resistance to platinum-based therapy is critical for improving the treatment of ovarian cancers. We have previously found that increased expression of annexin A3 is a mechanism for platinum resistance in ovarian cancer cells. Here we demonstrate that annexin A3 can be detected in the culture medium of ovarian cancer cells, particularly these cells that express high levels of annexin A3. Levels of annexin A3 were then determined in sera from ovarian cancer patients using an enzyme-linked immunosorbent assay. Compared with those from normal donors, sera from ovarian cancer patients contain significantly higher levels of annexin A3. Furthermore, serum levels of annexin A3 were significantly higher in platinum-resistant patients than in platinum-sensitive patients. To gain insight into the mechanism of secretion, the ovarian cancer cell lines were examined using both transmission electron microscopy and immunoelectron microscopy. Compared with parent cells, there are significantly more vesicles in the cytoplasm of ovarian cancer cells that express high levels of annexin A3, and at least some vesicles are annexin A3-positive. Moreover, some vesicles appear to be fused with the cell membrane, suggesting that annexin A3 secretion may be associated with exocytosis and the release of exosomes. This is supported by our observation that ovarian cancer cells expressing higher levels of annexin A3 released increased numbers of exosomes. Furthermore, annexin A3 can be detected in exosomes released from cisplatin-resistant cells (SKOV3/Cis) by immunoblotting and immunoelectron microscopy.

The role of annexin A1 in expression of matrix metalloproteinase-9 and invasion of breast cancer cells

Matrix metalloproteinase-9 (MMP-9) plays an important role in the invasion and metastasis of cancer cells. However, the regulatory mechanism of MMP-9 expression and its biological effects on breast cancer development remain obscure. In the current study, we examined the potential role of annexin A1 (ANXA1) in regulating migration and invasion in breast cancer cell lines. Both ANXA1 mRNA and protein are expressed in the highly invasive, hormone-insensitive human breast cancer cell lines MDA-MB-231 and SKBr3, but not in the hormone-responsive cell lines MCF-7 and T47D. Downregulation of ANXA1 expression with specific small interfering RNAs (ANXA1 siRNA) in MDA-MB-231 cells resulted in decreased cancer cell migration and invasion. Ablation of ANXA1 expression decreases the expression of MMP-9 at both the mRNA and protein levels and also reduces the proteolytic activity of MMP-9 in MDA-MB-231 cells. Moreover, silencing ANXA1 also decreases the transcriptional activity of MMP-9 by the suppression of nuclear factor kappa-B (NF-κB) activity. Collectively, these results indicate that ANXA1 functions as a positive regulator of MMP-9 expression and invasion of breast cancer cells through specific activation of the NF-κB signaling pathway.

Clinical significance of annexin A1 expression in breast cancer

PURPOSE

The expression of Annexin A1 (ANXA1) is known to be reduced in human breast cancer; however, the role of ANXA1 expression in the development of breast cancer remains unclear. In this study, we determined the relationship between the expression features of ANXA1 and the prognostic factors of breast cancer.

METHODS

Human breast tissues were obtained from patients specimens who had undergone breast surgery or core needle biopsies. The patterns of ANXA1 expression were analyzed by immunohistochemical staining in relation to histopathological diagnosis, clinical characteristics and outcomes.

RESULTS

One hundred eighty-two cases were included and the mean age of the patients was 46.34 ± 11.5 years. A significant loss of ANXA1 expression was noted in both ductal carcinoma in situ (DCIS) and invasive carcinomas compared to normal breast tissues (p<0.001) and benign breast diseases (p<0.001). There was a significant alteration in ANXA1 expression according to hormone receptor status (p<0.001), cancer intrinsic type (p<0.001), and nuclear grade (p=0.004) in invasive cancer. In a univariate analysis, ANXA1 positivity tended to be related with poor breast cancer-related survival (p=0.062); however, the same results was not realized in multivariate results (p=0.406). HER2 overexpression and TNM staging were significantly associated with relapse-free survivals (RFS) in the multivariate analysis (p=0.037, p=0.048, respectively). In particular, in node-positive patients (p=0.048), HER2 overexpressed patients (p=0.013), and non-triple negative breast cancer patients (p=0.002), ANXA1 overexpression was correlated with poor RFS.

CONCLUSION

Although significant loss of ANXA1 expression was noted in breast cancer including DCIS and invasive carcinoma, in cases of invasive cancer, overexpression of ANXA1 was related to unfavorable prognostic factors. And these results imply that ANXA1 plays dualistic roles and is involved in variable mechanisms related to cancer development and progression.

Modulation of septin and molecular motor recruitment in the microtubule environment of the Taxol-resistant human breast cancer cell line MDA-MB-231

Cell resistance to low doses of paclitaxel (Taxol) involves a modulation of microtubule (MT) dynamics. We applied a proteomic approach based on 2-DE coupled with MS to identify changes in the MT environment of Taxol-resistant breast cancer cells. Having established a proteomic pattern of the microtubular proteins extracted from MDA-MB-231 cells, we verified by Western blotting that in resistant cells, α- and β-tubulins (more specifically the βIII and βIV isotypes) increased. Interestingly, four septins (SEPT2, 8, 9 and 11), which are GTPases involved in cytokinesis and in MT/actin cytoskeleton organization, were overexpressed and enriched in the MT environment of Taxol-resistant cells compared to their sensitive counterpart. Changes in the MT proteome of resistant cells also comprised increased kinesin-1 heavy chain expression and recruitment on MTs while dynein light chain-1 was downregulated. Modulation of motor protein recruitment around MTs might reflect their important role in controlling MT dynamics via the organization of signaling pathways. The identification of proteins previously unknown to be linked to taxane-resistance could also be valuable to identify new biological markers of resistance.

Gaining insights into the Bcr-Abl activity-independent mechanisms of resistance to imatinib mesylate in KCL22 cells: a comparative proteomic approach

Imatinib mesylate is a potent inhibitor of Bcr-Abl tyrosine kinase, an oncoprotein that plays a key role in the development of chronic myeloid leukemia. Consequently, imatinib is used as front-line therapy for this disease. A major concern in imatinib treatment is the emergence of resistance to the drug. Here we used the imatinib-resistant KCL22R and imatinib-sensitive KCL22S cells in which none of the known resistance mechanisms has been detected and hence novel Bcr-Abl activity-independent mechanisms could be envisaged. We characterized proteins that were differentially expressed between the KCL22R and KCL22S cells. Using two-dimensional differential gel electrophoresis coupled with mass spectrometry and Western blot analysis we identified 51 differentially expressed proteins: 27 were over-expressed and 24 were under-expressed in KCL22R versus KCL22S cells. Several of these proteins are likely to be involved in such survival mechanisms as modulation of redox balance and activation of anti-apoptotic pathways mediated by NF-kappaB and Ras-MAPK signaling. The data reported may be useful for further studies on mechanisms of imatinib resistance and for the screening of biomarkers to develop new combinatorial therapeutic approaches.

Involvement of annexin A1 in multidrug resistance of K562/ADR cells identified by the proteomic study

Multidrug resistance (MDR) to chemotherapy is a significant barrier to the effective treatment of chromic myeloid leukemia (CML). In an attempt to identify more factors associated with MDR for an understanding of the mechanism, we first established an adriamycin (ADR)-resistant human erythroleukemia cell line K562/ADR by stepwise selection in vitro using ADR. Besides the elevated resistance to ADR, the K562/ADR cells also showed significantly increased crossed-resistance to vincristin and Gleevec, compared to the parental K562 cells. Then we compared the global protein profiles between K562 and K562/ADR cells. Following two-dimensional gel electrophoresis and image analysis, some of the proteins with different levels between the two cell lines were identified by MALDI TOF/TOF mass spectrometry and Western blot analysis. The differentially expressed proteins were classified into groups based on their functions: calcium-binding proteins, chaperones, metabolic enzymes, proteins related to protein synthesis or DNA synthesis, and proteins related to signal transduction. In particular, ANXA1, a protein that was downregulated in K562/ADR, was analyzed further for its involvement in MDR by transfection and subsequent assays. The functional validation showed that the downregulated ANXA1 expression contributes considerably to the observed drug resistance in K562/ADR cells. These data will be valuable for further study of the mechanisms of MDR and may reveal a potential new diagnostic marker to chemotherapy.

Increased expression of annexin A3 is a mechanism of platinum resistance in ovarian cancer

Resistance to platinum drugs has emerged as a major obstacle in the treatment of ovarian cancers. Through proteomic analysis, we have found that the expression of annexin A3, a member of the Ca(2+) and phospholipid-binding annexin family, is significantly increased in platinum-resistant ovarian cell lines. Anti-annexin A3 immunostaining indicated that cancers from platinum-resistant patients also possess higher levels of annexin A3 than those from platinum-sensitive patients. Although expression of annexin A3 made susceptible ovarian cancer cells more resistant to platinum, expression of antisense annexin A3 downregulated its expression and rendered the resistant cells more sensitive to platinum. In athymic mice, the growth of tumors from inoculated SKOV3 cells was inhibited by the administration of platinum, whereas tumors from annexin A3-expressing SKOV3/Ann were resistant to platinum treatment. Interestingly, the intracellular platinum concentration and platinum-DNA binding are significantly lower in annexin A3-overexpressing cells than those in parental cells. The lower cisplatin concentration was also accompanied by reduced induction of p53, which could be restored by downregulation of annexin A3. These results indicate that increased expression of annexin A3 is a mechanism of platinum resistance in ovarian cancer. It seems to act by preventing uptake or accumulation of platinum in cells. Therefore, it is conceivable that annexin A3 could be a target for therapeutic intervention and may also serve as a biomarker for drug resistance in ovarian cancer patients.

Rescue of paclitaxel sensitivity by repression of Prohibitin1 in drug-resistant cancer cells

Paclitaxel has emerged as a front line treatment for aggressive malignancies of the breast, lung, and ovary. Successful therapy of cancer is frequently undermined by the development of paclitaxel resistance. There is a growing need to find other therapeutic targets to facilitate treatment of drug-resistant cancers. Using a proteomics approach, elevated levels of Prohibitin1 (PHB1) and GSTpi were found associated with paclitaxel resistance in discrete subcellular fractions of two drug-resistant sublines relative to their sensitive sublines. Immunofluorescence staining and fractionation studies revealed increased levels of PHB1 on the surface of resistant cell lines. Transiently silencing either PHB1 or GSTpi gene expression using siRNA in the paclitaxel-resistant cancer cell sublines partially sensitized these cells toward paclitaxel. Intriguingly, silencing PHB1 but not GSTpi resulted in activation of the intrinsic apoptosis pathway in response to paclitaxel. Similarly, stably silencing either PHB1 or GSTpi significantly improved paclitaxel sensitivity in A549TR cells both in vitro and in vivo. Our results indicate that PHB1 is a mediator of paclitaxel resistance and that this resistance may depend on the cellular localization of the protein. We suggest PHB1 as a potential target for therapeutic strategies for the treatment of drug-resistant tumors.

Suppression of annexin A11 in ovarian cancer: implications in chemoresistance

Ovarian cancer patients treated with cisplatin-based chemotherapy often develop acquired cisplatin resistance and, consequently, cancer recurrence. We have previously reported that annexin A11 is associated with cisplatin resistance and related to tumor recurrence in ovarian cancer patients. In this study, we used small interfering RNA to suppress annexin A11 expression in ovarian cancer cells followed by various in vitro assays. We showed that knockdown of annexin A11 expression reduced cell proliferation and colony formation ability of ovarian cancer cells. Epigenetic silencing of annexin A11 conferred cisplatin resistance to ovarian cancer cells. Through a comprehensive time course study of cisplatin response in ovarian cancer cells with/without suppression of annexin A11 expression using whole-genome oligonucleotide microarrays, we identified a set of differentially expressed genes associated with annexin A11 expression and some patterns of gene expressions in response to cisplatin exposure. These identified genes/patterns were further validated by real-time polymerase chain reaction and immunoblot analysis. Many of them such as HMOX1, TGFBI, LY6D, S100P, EIF4EBP2, DHRS2, and PCSK9 have been involved in apoptosis, cell cycling/proliferation, cell adhesion/migration, transcription regulation, and signal transduction. In addition, immunohistochemistry analyses indicated that annexin A11 immunointensity inversely correlated with HMOX1 immunoreactivity in 142 ovarian cancer patients. In contrast to annexin A11, HMOX1 immunoreactivity positively correlated with in vitro cisplatin resistance in ovarian cancers. Collectively, annexin A11 is directly involved in cell proliferation and cisplatin resistance of ovarian cancer. Manipulation of annexin A11 and its associated genes may represent a novel therapeutic strategy in human ovarian cancers.

Evaluation of (64)Cu(DO3A-xy-TPEP) as a potential PET radiotracer for monitoring tumor multidrug resistance

In this study, we evaluated the potential of (64)Cu(DO3A-xy-TPEP) (DO3A-xy-TPEP = (2-(diphenylphosphoryl)ethyl)diphenyl(4-((4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)methyl)benzyl)phosphonium) as a PET (positron emission tomography) radiotracer for noninvasive monitoring of multidrug resistance (MDR) transport function in several xenografted tumor models (MDR-negative: U87MG; MDR-positive: MDA-MB-435, MDA-MB-231, KB-3-1, and KB-v-1). It was found that (64)Cu(DO3A-xy-TPEP) has a high initial tumor uptake (5.27 +/- 1.2%ID/g at 5 min p.i.) and shows a steady uptake increase between 30 and 120 min p.i. (2.09 +/- 0.53 and 3.35 +/- 1.27%ID/g at 30 and 120 min p.i., respectively) in the MDR-negative U87MG glioma tumors. (64)Cu(DO3A-xy-TPEP) has a greater uptake difference between U87MG glioma and MDR-positive tumors (MDA-MB-231: 1.57 +/- 0.04, 1.00 +/- 0.17, and 0.93 +/- 0.15; MDA-MB-435: 1.15 +/- 0.19, 1.12 +/- 0.20, and 0.81 +/- 0.11; KB-3-1: 1.45 +/- 0.31, 1.43 +/- 0.16, and 1.08 +/- 0.19; and KB-v-1: 1.63 +/- 0.47, 1.81 +/- 0.31, and 1.14 +/- 0.22%ID/g at 30, 60, and 120 min p.i., respectively) than (99m)Tc-Sestamibi. Regardless of the source of MDR, the overall net effect is the rapid efflux of (64)Cu(DO3A-xy-TPEP) from tumor cells, which leads to a significant reduction of its tumor uptake. It was concluded that (64)Cu(DO3A-xy-TPEP) is more efficient than (99m)Tc-Sestamibi as the substrate for MDR P-glycoproteins (MDR Pgps) and multidrug resistance-associated proteins (MRPs), and might be a more efficient radiotracer for noninvasive monitoring of the tumor MDR transport function. (64)Cu(DO3A-xy-TPEP) and (99m)Tc-Sestamibi share almost identical subcellular distribution patterns in U87MG glioma tumors. Thus, it is reasonable to believe that (64)Cu(DO3A-xy-TPEP), like (99m)Tc-Sestamibi, is able to localize in mitochondria due to the increased plasma and mitochondrial transmembrane potentials in tumor cells.

Annexins in human breast cancer: Possible predictors of pathological response to neoadjuvant chemotherapy

Neoadjuvant chemotherapy is used in women who have large or locally advanced breast cancers. However, up to 70% of women who receive neoadjuvant chemotherapy fail to achieve a complete pathological response in their primary tumour (a surrogate marker of long-term survival). Five proteins, previously identified to be linked with chemoresistance in our in vitro experiments, were identified histochemically in pre-treatment core needle biopsies from 40 women with large or locally advanced breast cancers. Immunohistochemical staining with the five proteins showed no single protein to be a predictor of response to chemotherapy. However, pre-treatment breast cancer specimens that were annexin-A2 positive but annexin-A1 negative correlated with a poor pathological response (p=0.04, Fisher's exact test). The mechanisms by which annexins confer chemoresistance have not been identified, but may be due to inhibition of apoptosis. Annexin-A1 has been shown to enhance apoptosis, whilst annexin-A2, by contrast, inhibits apoptosis.

Annexin A1 regulates intestinal mucosal injury, inflammation, and repair

During mucosal inflammation, a complex array of proinflammatory and protective mechanisms regulates inflammation and severity of injury. Secretion of anti-inflammatory mediators is a mechanism that is critical in controlling inflammatory responses and promoting epithelial restitution and barrier recovery. AnxA1 is a potent anti-inflammatory protein that has been implicated to play a critical immune regulatory role in models of inflammation. Although AnxA1 has been shown to be secreted in intestinal mucosal tissues during inflammation, its potential role in modulating the injury/inflammatory response is not understood. In this study, we demonstrate that AnxA1-deficient animals exhibit increased susceptibility to dextran sulfate sodium (DSS)-induced colitis with greater clinical morbidity and histopathologic mucosal injury. Furthermore, impaired recovery following withdrawal of DSS administration was observed in AnxA1 (-/-) animals compared with wild-type (WT) control mice that was independent of inflammatory cell infiltration. Since AnxA1 exerts its anti-inflammatory properties through stimulation of ALX/FPRL-1, we explored the role of this receptor-ligand interaction in regulating DSS-induced colitis. Interestingly, treatment with an ALX/FPRL-1 agonist, 15-epi-lipoxin A4 reversed the enhanced sensitivity of AnxA1 (-/-) mice to DSS colitis. In contrast, 15-epi-lipoxin A4 did not significantly improve the severity of disease in WT animals. Additionally, differential expression of ALX/FPLR-1 in control and DSS-treated WT and AnxA1-deficient animals suggested a potential role for AnxA1 in regulating ALX/FPRL-1 expression under pathophysiological conditions. Together, these results support a role of endogenous AnxA1 in the protective and reparative properties of the intestinal mucosal epithelium.

The role of annexins in tumour development and progression

The annexins are a super-family of closely related calcium and membrane-binding proteins. They have a diverse range of cellular functions that include vesicle trafficking, cell division, apoptosis, calcium signalling and growth regulation. Many studies have shown the annexins to be among the genes whose expression are consistently differentially altered in neoplasia. Some annexins show increased expression in specific types of tumours, while others show loss of expression. Mechanistic studies relating the changes in annexin expression to tumour cell function, particularly tumour invasion and metastasis, angiogenesis and drug resistance, are now also emerging. Changes in the expression of individual annexins are associated with particular types of tumour and hence the annexins may also be useful biomarkers in the clinic.

A proteomic kinetic analysis of IGROV1 ovarian carcinoma cell line response to cisplatin treatment

Ovarian cancer is one of the leading causes of mortality by gynecological cancer. Despite good response to surgery and initial chemotherapy, essentially based on cisplatin (cis-diamino-dichloro-platinum(II) (CDDP)) compounds, frequent recurrences with chemoresistance acquisition are responsible for poor prognosis. Several mechanisms have been described as implicated in CDDP resistance, however they are not sufficient to exhaustively account for this resistance emergence. We applied a proteomic approach based on 2-DE coupled with MS (MALDI-TOF/TOF) to identify proteins associated with chemoresistance induced by CDDP. A kinetic analysis of IGROV1 cell behavior following treatment with CDDP and subsequent statistical analysis revealed time and/or concentration-dependent modifications in protein expression. We evidenced events such as decreased amino-acid and nucleotide synthesis potentially associated with cell cycle blockade, and variations that may be related to resistance acquisition, such as possible enhanced glycolysis and increased proliferating potential. Moreover, overexpressions of aldehyde dehydrogenase 1 and both cytokeratins 8 and 18 were consistent with our previous findings, demonstrating that expression of these proteins was increased in cisplatin-resistant IGROV1-R10 as compared to IGROV1 parental cells. Identification of such proteins could allow improved understanding of the mechanisms leading to cell death or survival and, thus, to the acquisition of chemoresistance.

Annexin XI is associated with cisplatin resistance and related to tumor recurrence in ovarian cancer patients

PURPOSE

Ovarian cancer patients treated with cisplatin-based chemotherapy often develop acquired cisplatin resistance and, consequently, cancer recurrence. The precise nature of chemoresistance remains unclear. In this study, a protein identified to be associated with cisplatin resistance in ovarian cancer cells was investigated in ovarian cancer tissues to address its clinical significance.

EXPERIMENTAL DESIGN

Antibody microarrays were used to identify proteins consistently differentially expressed across three pairs of cisplatin-sensitive and cisplatin-resistant ovarian cancer cell lines. Immunoblotting was used to confirm observed alteration of protein expression. The protein expression was further evaluated by immunohistochemical staining using tissue microarrays containing various human normal and malignant tissues and 164 surgical specimens derived from primary and recurrent ovarian cancer patients who underwent primary debulking surgery followed by standard chemotherapeutic regimen.

RESULTS

Annexin XI was down-regulated in all three cisplatin-resistant cell lines as compared with their parent cells. Annexin XI expression was observed in the majority of human normal organs and decreased in some of the most common human malignancies. The expression level of Annexin XI in first recurrent ovarian cancers was much lower than that in primary ovarian cancers (P = 0.0004). Increased Annexin XI immunoreactivity in ovarian cancers seemed to prolong the disease-free interval of patients (P = 0.03). Annexin XI immunoreactivity inversely correlated with in vitro cisplatin resistance in ovarian cancers (P = 0.01).

CONCLUSION

Decreased expression of Annexin XI is characteristic for cisplatin-resistant cancer cells and may contribute to tumor recurrence. Annexin XI may be a potential marker for chemoresistance and earlier recurrence of ovarian cancer patients.

Use of comparative proteomics to identify potential resistance mechanisms in cancer treatment

Drug resistance is a major problem in successful cancer chemotherapy. Many molecular mechanisms that are responsible for drug resistance are known whereas others have yet to be discovered. Determining the exact mechanism activated in a particular case (clinical or laboratory) is a difficult task. Recently, proteomics has been applied to investigate drug resistance mechanisms in model cancer cell lines. As a result, novel mechanisms of resistance have been discovered and known mechanisms of resistance confirmed. In this paper, we wish to review recent developments and progresses in the application of proteomic tools to identify known and novel drug resistance mechanisms in drug-selected model cancer cell lines. Our combined analyses of multiple proteomic studies of various drug resistant cancer cell lines revealed that many mechanisms of resistance likely exist in any given drug-selected cancer cell line and that common mechanisms of resistance may be selected in a spectrum of cancer cell lines. These observations suggest that combination therapies targeting multiple mechanisms to sensitize drug resistant cancers may be necessary to eradicate cancers in the future.

The use of an in vitro adenosine triphosphate-based chemotherapy response assay to predict chemotherapeutic response in breast cancer

The adenosine triphosphate-based chemotherapy response assay (ATP-CRA) has the advantages of standardization, evaluability, reproducibility, and accuracy, and can be performed on relatively small numbers of tumor cells. A total of 43 patients were enrolled in the present study, and chemosensitivity tests were successfully performed in 40 (93.0%) of these patients. Twenty of the 40 received neoadjuvant chemotherapy or chemotherapy for metastatic breast cancer. The chemotherapy regimens used were doxorubicin plus docetaxel (n=9, 45.0%) or doxorubicin plus paclitaxel (n=11, 55.0%). Mean cell death rate, as determined by ATP-CRA, was lower in non-responders than in responders to therapy (P=0.012). Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for ATP-CRA were 78.6%, 100%, 100%, 66.7%, and 85.0%, respectively. Diagnostic accuracy achieved by immunohistochemistry using estrogen receptor or progesterone receptor was lower than that achieved using ATP-CRA. Expression of p53, erb-B2, Ki67, Bcl-2, Bcl-xL, and annexin I was not significantly associated with response to chemotherapy. Our results show that ATP-CRA has high specificity and positive predictive value for predicting response to chemotherapy.

Genes and proteins differentially expressed during in vitro malignant transformation of bovine pancreatic duct cells

Pancreatic carcinoma has an extremely bad prognosis due to lack of early diagnostic markers and lack of effective therapeutic strategies. Recently, we have established an in vitro model recapitulating the first steps in the carcinogenesis of the pancreas. SV40 large T antigen-immortalized bovine pancreatic duct cells formed intrapancreatic adenocarcinoma tumors on k-ras(mut) transfection after orthotopic injection in the nude mouse pancreas. Here we identified genes and proteins differentially expressed in the course of malignant transformation using reciprocal suppression subtractive hybridization and 2D gel electrophoresis and mass spectrometry, respectively. We identified 34 differentially expressed genes, expressed sequence tags, and 15 unique proteins. Differential expression was verified for some of the genes or proteins in samples from pancreatic carcinoma. Among these genes and proteins, the majority had already been described either to be influenced by a mutated ras or to be differentially expressed in pancreatic adenocarcinoma, thus proving the feasibility of our model. Other genes and proteins (e.g., BBC1, GLTSCR2, and rhoGDIalpha), up to now, have not been implicated in pancreatic tumor development. Thus, we were able to establish an in vitro model of pancreatic carcinogenesis, which enabled us to identify genes and proteins differentially expressed during the early steps of malignant transformation.

A comparative study of protein profiling by proteomic analysis in camptothecin-resistant PC3 and camptothecin-sensitive LNCaP human prostate cancer cells

INTRODUCTION

Drug resistance is a major obstacle for the therapy of prostate cancer, but its underlying mechanisms are not clarified. To detect some candidate marker proteins which may confer resistance to the anticancer drug camptothecin (CPT; DNA topoisomerase 1 inhibitor), the current study deals with the comparative proteomic profiling of CPT-resistant PC3 and CPT-sensitive LNCaP human prostate cancer cell lines which have been widely employed as a useful model to investigate prostate cancer cells.

MATERIALS AND METHODS

The global profiling of the protein expression was investigated in CPT-resistant PC3 and CPT-sensitive LNCaP prostate cancer cells using 2-dimensional polyacrylamide gel electrophoresis/matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

RESULTS

144 proteins were identified and their expression levels were compared between the two cell lines. Four proteins - annexin A1, glutathione-S-transferase (GST) pi, galectin (Gal) 3 and glucose-regulated protein 78/Bip - that are suggested to contribute to the development of drug resistance were found to be preferentially or highly expressed in PC3 cells, whereas LNCaP cells did not show detectable expression of annexin A1, GST-pi and Gal-3.

CONCLUSION

The expression level of these proteins and/or mRNAs could be a useful parameter to evaluate the chemotherapy resistance in clinical specimens of prostate cancer.

Celecoxib enhances doxorubicin-induced cytotoxicity in MDA-MB231 cells by NF-κB-mediated increase of intracellular doxorubicin accumulation

Non-steroidal anti-inflammatory drugs (NSAIDs) and cyclo-oxygenase (COX) inhibitors are anti-inflammatory agents that have also shown to be useful in anticancer therapy. In the present study, we show that the specific COX-2 inhibitor celecoxib enhances the inhibitory effect of doxorubicin (dox) on human MDA-MB231 breast tumour growth in vivo and in vitro. We also found that celecoxib increased the intracellular accumulation and retention of dox in vitro. Since the NSAID indomethacin and the specific COX-2 inhibitor NS398 did not affect the in vitro actions of dox, these effects are likely to be mediated via a COX-independent mechanism. It has been suggested that some COX-inhibitors can enhance the actions of cytostatics by overcoming multidrug resistance through the inhibition of ABC-transporter proteins. However, we found that the three main ATP-binding cassette (ABC)-transporter proteins, implicated in dox transport, were inactive in MDA-MB231 cells. Therefore, the finding that the P-glycoprotein (P-gp) blocker PSC833 also increased cellular accumulation of dox was unexpected. In order to unravel the molecular mechanisms involved in dox accumulation, we examined the involvement of NF-kappaB, as this transcription factor has been implicated in celecoxib action as well as in chemoresistance. We found that celecoxib and PSC833, but not indomethacin or NS398, almost completely inhibited basal- and dox induced NF-kappaB gene-reporter activity and p65 subunit nuclear translocation. Furthermore, the NF-kappaB inhibitor PDTC mimicked the actions of celecoxib and PSC833 on cell growth and on intracellular accumulation of dox, suggesting that NF-kappaB is functionally involved in the actions of these compounds. In conclusion, we show that structurally different compounds, among which are celecoxib and PSC833, increase the intracellular accumulation of dox and enhance dox induced cytotoxicity in MDA-MB231 breast cancer cells most likely via the modulation of NF-kappaB activity.