Paclitaxel inhibits expression of heat shock protein 27 in ovarian and uterine cancer cells

Biological activities and ecological aspects of Limonium pruinosum (L.) collected from Wadi Hof Eastern Desert, Egypt, as a promising attempt for potential medical applications

Very few researchers have focused on the biological efficacy of Limonium plants. In this concern, no investigations were commenced to delve into the in vitro and ex vivo biological actions of Limonium pruinosum in Egypt. Therefore, this work aims to assess for the first time the antimicrobial, antioxidant, and antitumor activities of Limonium pruinosum extract in addition to studying its ability to suppress the transcription of cell cycle–stimulating genes. L. pruinosum ethyl acetate extract exhibits considerable antibacterial and antibiofilm activity versus E. coli ATCC 25922 and Staphylococcus aureus ATCC 25923. Results revealed that L. pruinosum exerts antioxidant effectiveness concerning DPPH, nitric oxide (NO), and hydroxyl radical (OH) scavenging ability with an IC50 (35.88 ± 2.2, 51.31 ± 1.06, and 65.87 ± 1.19 μg/mL) respectively. The results proved the effectiveness of L. pruinosum in closing wounds in gastric epithelial cells (GES-1) by (79.9343 ± 1.98%) compared with control (68.3637 ± 2.32%) in 48 h. Additionally, L. pruinosum had anticancer activity contrary to breast cancer MCF-7 and liver cancer HepG-2 cell lines with IC50 values of 96.73 ± 2.18 and 81.81 ± 0.99 μg/mL, respectively, while it had no cytotoxic activity against (Wi-38) normal cells. Also, L. pruinosum extract provoked considerable early- and late-apoptotic cell populations and was effective in inducing cell death of MCF-7. Our findings evoked that L. pruinosum has promising antibacterial, antioxidant, and wound healing activities and a good breast tumor suppressor arresting the cell cycle-stimulating genes, which may be an auspicious approach for the treatment of breast cancer.

The Role of Hsp27 in Chemotherapy Resistance

Heat shock protein (Hsp)-27 is a small-sized, ATP-independent, chaperone molecule that is overexpressed under conditions of cellular stress such as oxidative stress and heat shock, and protects proteins from unfolding, thus facilitating proteostasis and cellular survival. Despite its protective role in normal cell physiology, Hsp27 overexpression in various cancer cell lines is implicated in tumor initiation, progression, and metastasis through various mechanisms, including modulation of the SWH pathway, inhibition of apoptosis, promotion of EMT, adaptation of CSCs in the tumor microenvironment and induction of angiogenesis. Investigation of the role of Hsp27 in the resistance of various cancer cell types against doxorubicin, herceptin/trastuzumab, gemcitabine, 5-FU, temozolomide, and paclitaxel suggested that Hsp27 overexpression promotes cancer cell survival against the above-mentioned chemotherapeutic agents. Conversely, Hsp27 inhibition increased the efficacy of those chemotherapy drugs, both in vitro and in vivo. Although numerous signaling pathways and molecular mechanisms were implicated in that chemotherapy resistance, Hsp27 most commonly contributed to the upregulation of Akt/mTOR signaling cascade and inactivation of p53, thus inhibiting the chemotherapy-mediated induction of apoptosis. Blockage of Hsp27 could enhance the cytotoxic effect of well-established chemotherapeutic drugs, especially in difficult-to-treat cancer types, ultimately improving patients' outcomes.

Paclitaxel increases sensitivity of SKOV3 cells to hyperthermia by inhibiting heat shock protein 27

Hyperthermic intraperitoneal chemotherapy (HIPEC) is a promising treatment strategy for patients with peritoneal metastasis of ovarian cancer. Heat shock proteins (HSPs) play an important role in cellular stress during HIPEC treatment. The aim of the present study was to investigate whether paclitaxel can exert antitumor effects by inhibiting heat shock protein 27 (HSP27) expression during HIPEC treatment. Cell viability was detected by CCK8 assay. We used Western blot analysis to detect HSP27 expression under hyperthermia conditions with or without paclitaxel in SKOV3 cells. To further examine the role of HSP27 in the apoptosis, Bcl-2, Bax and Caspase-3 protein expression were additionally determined after reducing HSP27 levels using an siRNA strategy, and apoptosis was detected using the Annexin V/PI assay. The upregulation of HSP27 expression was accompanied with a rise in temperature. In addition, HSP27 could promote Bcl-2 expression, inhibit Bax and Caspase-3 expression, reduce the Bax / Bcl-2 ratio markedly in SKOV3 cells. Furthermore, paclitaxel could upregulate the Bax / Bcl-2 ratio by inhibiting HSP27 expression, and in turn, promoting apoptosis due to hyperthermia. Paclitaxel could also promote apoptosis by inhibiting HSP27 in SKOV3 cells. Our results demonstrate a synergistic effect between paclitaxel and hyperthermia at the cellular level.

Heat Shock Proteins and Ovarian Cancer: Important Roles and Therapeutic Opportunities

Ovarian cancer is a serious cause of death in gynecological oncology. Delayed diagnosis and poor survival rates associated with late stages of the disease are major obstacles against treatment efforts. Heat shock proteins (HSPs) are stress responsive molecules known to be crucial in many cancer types including ovarian cancer. Clusterin (CLU), a unique chaperone protein with analogous oncogenic criteria to HSPs, has also been proven to confer resistance to anti-cancer drugs. Indeed, these chaperone molecules have been implicated in diagnosis, prognosis, metastasis and aggressiveness of various cancers. However, relative to other cancers, there is limited body of knowledge about the molecular roles of these chaperones in ovarian cancer. In the current review, we shed light on the diverse roles of HSPs as well as related chaperone proteins like CLU in the pathogenesis of ovarian cancer and elucidate their potential as effective drug targets.

Overcoming HSP27-mediated resistance by altered dimerization of HSP27 using small molecules

Heat shock protein 27 (HSP27, HSPB1) is an anti-apoptotic protein characterized for its tumorigenic and metastatic properties, and now referenced as a major therapeutic target in many types of cancer. The biochemical properties of HSP27 rely on a structural oligomeric and dynamic organization that is important for its chaperone activity. Down-regulation by small interfering RNA or inhibition with a dominant-negative mutant efficiently counteracts the anti-apoptotic and protective properties of HSP27. However, unlike other HSPs such as HSP90 and HSP70, small molecule approaches for neutralization of HSP27 are not well established because of the absence of an ATP binding domain. Previously, we found that a small molecule, zerumbone (ZER), induced altered dimerization of HSP27 by cross linking the cysteine residues required to build a large oligomer, led to sensitization in combination with radiation. In this study, we identified another small molecule, a xanthone compound, more capable of altering dimeric HSP27 than ZER and yielding sensitization in human lung cancer cells when combined with HSP90 inhibitors or standard anticancer modalities such as irradiation and cytotoxic anticancer drugs. Therefore, altered dimerization of HSP27 represents a good strategy for anticancer therapy in HSP27-overexpressing cancer cells.

HSP27 Knockdown Increases Cytoplasmic p21 and Cisplatin Sensitivity in Ovarian Carcinoma Cells

Drug resistance is the leading cause of chemotherapy failure in the treatment of ovarian cancer. So far, little is known about the mechanism of chemoresistance in ovarian cancer. In this study, we explored the mechanism that HSP27 was involved in cisplatin resistance of ovarian cancer both in vitro and clinically. HSP27 protein was found to be upregulated and expressed in cisplatin-resistant ovarian cancer cell line C13*, and HSP27 siRNA transfection reversed the chemoresistance of C13*. We found that HSP27 exerted its chemoresistant role by inhibiting p21 transferring from the nucleus to the plasma through the activation of phosphorylated-Akt pathway. These findings have implications for clinical trials aimed at a potential therapeutic target for ovarian tumors that are refractory to conventional treatment.

The Clinical Significance of Phosphorylated Heat Shock Protein 27 (HSPB1) in Pancreatic Cancer

Pancreatic cancer is one of most aggressive forms of cancer. After clinical detection it exhibits fast metastatic growth. Heat shock protein 27 (HSP27; HSPB1) has been characterized as a molecular chaperone which modifies the structures and functions of other proteins in cells when they are exposed to various stresses, such as chemotherapy. While the administration of gemcitabine, an anti-tumor drug, has been the standard treatment for patients with advanced pancreatic cancer, accumulating evidence shows that HSP27 plays a key role in the chemosensitivity to gemcitabine. In addition, phosphorylated HSP27 induced by gemcitabine has been associated with the inhibition of pancreatic cancer cell growth. In this review, we summarize the role of phosphorylated HSP27, as well as HSP27, in the regulation of chemosensitivity in pancreatic cancer.

Jump in the fire--heat shock proteins and their impact on ovarian cancer therapy

Ovarian cancer (OC) is a major problem in gynecological oncology. Options for diagnosis and treatment of advanced stages and thus for patient prognosis have not been improved substantially over the past decades. Heat shock proteins (HSP) are characterized as stress-induced molecular chaperones performing cell survival factor functions. In cancer cells, various crucial and clinically important cell responses are vitally influenced and modulated by HSPs, e.g., cell growth and treatment resistance. Despite the limited knowledge on HSPs in OC progression, their roles as biomarkers, prognostic factors and their drug target properties appears promising for future clinical applications and therapeutic approaches.

MT-4 suppresses resistant ovarian cancer growth through targeting tubulin and HSP27

OBJECTIVE

In this study, the anticancer mechanisms of MT-4 were examined in A2780 and multidrug-resistant NCI-ADR/res human ovarian cancer cell lines.

METHODS

To evaluate the activity of MT-4, we performed in vitro cell viability and cell cycle assays and in vivo xenograft assays. Immunoblotting analysis was carried out to evaluate the effect of MT-4 on ovarian cancer. Tubulin polymerization was determined using a tubulin binding assay.

RESULTS

MT-4 (2-Methoxy-5-[2-(3,4,5-trimethoxy-phenyl)-ethyl]-phenol), a derivative of moscatilin, can inhibit both sensitive A2780 and multidrug-resistant NCI-ADR/res cell growth and viability. MT-4 inhibited tubulin polymerization to induce G2/M arrest followed by caspase-mediated apoptosis. Further studies indicated that MT-4 is not a substrate of P-glycoprotein (p-gp). MT-4 also caused G2/M cell cycle arrest, accompanied by the upregulation of cyclin B, p-Thr161 Cdc2/p34, polo-like kinase 1 (PLK1), Aurora kinase B, and phospho-Ser10-histone H3 protein levels. In addition, we found that p38 MAPK pathway activation was involved in MT-4-induced apoptosis. Most importantly, MT-4 also decreased heat shock protein 27 expression and reduced its interaction with caspase-3, which inured cancer cells to chemotherapy resistance. Treatment of cells with SB203580 or overexpression of dominant negative (DN)-p38 or wild-type HSP27 reduced PARP cleavage caused by MT-4. MT-4 induced apoptosis through regulation of p38 and HSP27. Our xenograft models also show the in vivo efficacy of MT-4. MT-4 inhibited both A2780 and NCI-ADR/res cell growth in vitro and in vivo.

CONCLUSION

These findings indicate that MT-4 could be a potential lead compound for the treatment of multidrug-resistant ovarian cancer.

Differential protein expressions in breast cancer between drug sensitive tissues and drug resistant tissues

OBJECTIVE

To investigate the differential expression of the sensitive and resistant relative proteins in human breast cancer tissue.

METHODS

A drug sensitive group and a drug resistant group for chemotherapy in patients with breast cancer were selected through neoadjuvant therapy. The differential protein expression in 2 groups was detected by proteomic techniques, and parts of differential proteins were identified by Western blotting.

RESULTS

There were 13 differential proteins in the 2 groups, in which the expression of 3 proteins was up-regulated and 10 down-regulated. Seven proteins were identified by Western blotting. The expressions of keratin type I cytoskeletal 19 (KIC19) and thymidine phosphorylase (TYPH) were up-regulated, and the expressions of heat shock protein 27 (HSP27), keratin type I cytoskeletal 9 (KIC9), collagen alpha-2(VI) (CO6A2), vimentin (VIME), and actin cytoplasmic 1 (ACTB) were down-regulated in the drug resistant group. There were significant differences between these 2 groups (P<0.01).

CONCLUSIONS

The expressions of KIC19 and TYPH may be correlated with drug resistance in patients with breast cancer, and HSP27, KIC9, CO6A2, VIME, and ACTB may be correlated with drug sensitivity.

HspB1, HspB5 and HspB4 in Human Cancers: Potent Oncogenic Role of Some of Their Client Proteins

Human small heat shock proteins are molecular chaperones that regulate fundamental cellular processes in normal unstressed cells as well as in many cancer cells where they are over-expressed. These proteins are characterized by cell physiology dependent changes in their oligomerization and phosphorylation status. These structural changes allow them to interact with many different client proteins that subsequently display modified activity and/or half-life. Nowdays, the protein interactomes of small Hsps are under intense investigations and will represent, when completed, key parameters to elaborate therapeutic strategies aimed at modulating the functions of these chaperones. Here, we have analyzed the potential pro-cancerous roles of several client proteins that have been described so far to interact with HspB1 (Hsp27) and its close members HspB5 (αB-crystallin) and HspB4 (αA-crystallin).

MPT0B098, a novel microtubule inhibitor that destabilizes the hypoxia-inducible factor-1α mRNA through decreasing nuclear-cytoplasmic translocation of RNA-binding protein HuR

Microtubule inhibitors have been shown to inhibit hypoxia-inducible factor-1α (HIF-1α) expression through inhibition translation or enhancing protein degradation. Little is known of the effect of microtubule inhibitors on the stability of HIF-1α mRNA. We recently discovered a novel indoline-sulfonamide compound, 7-aryl-indoline-1-benzene-sulfonamide (MPT0B098), as a potent microtubule inhibitor through binding to the colchicine-binding site of tubulin. MPT0B098 is active against the growth of various human cancer cells, including chemoresistant cells with IC50 values ranging from 70 to 150 nmol/L. However, normal cells, such as human umbilical vein endothelial cells (HUVEC), exhibit less susceptibility to the inhibitory effect of MPT0B098 with IC50 of 510 nmol/L. Similar to typical microtubule inhibitors, MPT0B098 arrests cells in the G2-M phase and subsequently induces cell apoptosis. In addition, MPT0B098 effectively suppresses VEGF-induced cell migration and capillary-like tube formation of HUVECs. Distinguished from other microtubule inhibitors, MPT0B098 not only inhibited the expression levels of HIF-1α protein but also destabilized HIF-1α mRNA. The mechanism of causing unstable of HIF-1α mRNA by MPT0B098 is through decreasing RNA-binding protein, HuR, translocation from the nucleus to the cytoplasm. Notably, MPT0B098 effectively suppresses tumor growth and microvessel density of tumor specimens in vivo. Taken together, our results provide a novel mechanism of inhibiting HIF-1α of a microtubule inhibitor MPT0B098. MPT0B098 is a promising anticancer drug candidate with potential for the treatment of human malignancies.

Do liposomal apoptotic enhancers increase tumor coagulation and end-point survival in percutaneous radiofrequency ablation of tumors in a rat tumor model?

PURPOSE

To characterize effects of combining radiofrequency (RF) ablation with proapoptotic intravenous liposome-encapsulated paclitaxel and doxorubicin on tumor destruction, apoptosis and heat-shock protein (HSP) production, intratumoral drug accumulation, and end-point survival.

MATERIALS AND METHODS

R3230 mammary adenocarcinomas (n = 177) were implanted in 174 rats in this animal care committee-approved study. Tumors received (a) no treatment, (b) RF ablation, (c) paclitaxel, (d) RF ablation followed by paclitaxel (RF ablation-paclitaxel), (e) paclitaxel before RF ablation (paclitaxel-RF ablation), (f) RF ablation followed by doxorubicin (RF ablation-doxorubicin), (g) paclitaxel followed by doxorubicin without RF ablation (paclitaxel-doxorubicin), or (h) paclitaxel before RF ablation, followed by doxorubicin (paclitaxel-RF ablation-doxorubicin). Tumor coagulation area and diameter were compared at 24-96 hours after treatment. Intratumoral paclitaxel uptake with and without RF ablation were compared. Immunohistochemical staining revealed cleaved caspase-3 and 70-kDa HSP (HSP70) expression. Tumors were randomized into eight treatment arms for Kaplan-Meier analysis of defined survival end-point (3.0-cm diameter).

RESULTS

Paclitaxel-RF ablation increased tumor coagulation over RF ablation or paclitaxel (mean, 14.0 mm ± 0.9 [standard deviation], 6.7 mm ± 0.6, 2.5 mm ± 0.6, respectively; P < .001). Paclitaxel-RF ablation-doxorubicin had similar tumor coagulation (P < .05), compared with paclitaxel-RF ablation, at 24 and 96 hours. Mean intratumoral paclitaxel accumulation for paclitaxel-RF ablation (6.76 μg/g ± 0.35) and RF ablation-paclitaxel (9.28 μg/g ± 0.87) increased over that for paclitaxel (0.63 μg/g ± 0.25, P < .001). Paclitaxel substantially increased apoptosis and decreased HSP70 expression at coagulation margin. Mean end-point survival for paclitaxel-RF ablation-doxorubicin (56.8 days ± 25.3) was greater, compared with that for paclitaxel-RF ablation or RF ablation-paclitaxel (17.6 days ± 2.5), RF ablation-doxorubicin (30.3 days ± 4.9, P < .002), or paclitaxel-doxorubicin (27.9 days ± 4.1, P < .001).

CONCLUSION

Selecting adjuvant liposomal chemotherapies (paclitaxel, doxorubicin) to target cellular apoptosis and HSP production effectively increases RF ablation-induced tumor coagulation and end-point survival, and combined multidrug approach results in even better outcomes.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100500/-/DC1.

Cancer cells acquire mitotic drug resistance properties through beta I-tubulin mutations and alterations in the expression of beta-tubulin isotypes

BACKGROUND

Anti-mitotic compounds (microtubule de-stabilizers) such as vincristine and vinblastine have been shown clinically successful in treating various cancers. However, development of drug-resistance cells limits their efficacies in clinical situations. Therefore, experiments were performed to determine possible drug resistance mechanisms related to the application of anti-mitotic cancer therapy.

PRINCIPAL FINDINGS

A KB-derived microtubule de-stabilizer-resistant KB-L30 cancer cell line was generated for this study. KB-L30 cells showed cross-resistance to various microtubule de-stabilizers including BPR0L075, vincristine and colchicine through multiple-drug resistant (MDR)-independent mechanisms. Surprisingly, KB-L30 cells showed hyper-sensitivity to the microtubule-stabilizer, paclitaxel. Results of the RT-PCR analysis revealed that expression of both class II and III β-tubulin was down-regulated in KB-L30 cells as compared to its parental KB cancer cells. In addition, DNA sequencing analysis revealed six novel mutation sites present in exon four of the βI-tubulin gene. Computational modeling indicated that a direct relationship exists between βI-tubulin mutations and alteration in the microtubule assembly and dynamic instability in KB-L30 cells and this predicted model was supported by an increased microtubule assembly and reduced microtubule dynamic instability in KB-L30 cells, as shown by Western blot analysis.

CONCLUSIONS AND SIGNIFICANCE

Our study demonstrated that these novel mutations in exon four of the βI-tubulin induced resistance to microtubule de-stabilizers and hyper-sensitivity to microtubule stabilizer through an alteration in the microtubule assembly and dynamics in cancer cells. Importantly, the current study reveals that cancer cells may acquire drug resistance ability to anti-mitotic compounds through multiple changes in the microtubule networks. This study further provided molecular information in drug selection for patients with specific tubulin mutations.

Glycoproteomics of paclitaxel resistance in human epithelial ovarian cancer cell lines: towards the identification of putative biomarkers

Glycosylation, one of the most common post translational modifications (PTMs) of proteins, is often associated with carcinogenesis and tumor malignancy. Ovarian cancer is the sixth cause of cancer-related death in Western countries. Currently, it is treated by debulking surgery followed by chemotherapy based on paclitaxel, alone or in combination with other drugs. However, chemoresistance represents a major obstacle to positive clinical outcome. We used two approaches, Multiplexed Proteomics (MP) technology and Multilectin Affinity Chromatography (MAC) to characterize the glycoproteome of the human ovarian cancer cell line A2780 and its paclitaxel resistant counterpart A2780TC1. Furthermore proteins were separated by traditional 2DE or DIGE and identified by MS (MALDI TOF or LC MS/MS). Seventy glycoproteins were successfully identified in ovarian cancer cells and 10 were found to be differentially expressed between sensitive and resistant cell lines. We focused on four glycoproteins (tumor rejection antigen (gp96) 1, triose phosphate isomerase, palmitoyl-protein thioesterase 1 precursor and ER-associated DNAJ) which were remarkably upregulated in A2780TC1 compared to A2780 cell line and which may represent biomarkers for paclitaxel resistance in ovarian cancer.

Concentrations of antibodies against heat shock protein 27 in the sera of women with ovarian carcinoma

INTRODUCTION

Heat shock proteins (Hsp) are highly expressed in many malignant human tumors, including tumors of the genital tract. One of the Hsps strongly associated with the process of cancerogenesis is Hsp27. The presence of Hsp27 and anti-Hsp27 in the sera of patients with ovarian carcinoma is still a new research field, and papers contain contradictory results. The aim of this work was to study the concentrations of anti-Hsp27 immunoglobulin G antibodies in the sera of women with ovarian cancer at different clinical stages and with different histopathological types of this cancer.

METHODS

Serum samples from 158 patients with ovarian carcinoma and 80 healthy women were investigated. The concentrations of anti-Hsp27 antibodies were determined by the enzyme-linked immunosorbent assay technique.

RESULTS

The mean concentration of anti-Hsp27 antibodies in the patients with ovarian carcinoma was significantly higher than that in the control group. Analysis in relation to the stage of clinical progression showed that the less advanced the cancerogenesis process, the higher the concentration of the anti-Hsp27 antibodies is. The mean concentrations of the anti-Hsp27 antibodies in the patients with ovarian carcinoma were not significantly different in relation to the histological type of the cancer. The use of chemotherapy as a primary anticancer treatment in ovarian carcinoma did not cause a significant decrease in the concentration of anti-Hsp27 antibodies.

CONCLUSIONS

An immunological response to Hsp27 is increased in women with ovarian carcinoma. Although the diagnostic concentrations of anti-Hsp27 antibodies have not been precisely defined yet, we believe that this may be a helpful diagnostic parameter particularly to detect early stages of clinical advancement of the disease.

Small Interfering RNA-Mediated Silencing of Heat Shock Protein 27 (HSP27) Increases Chemosensitivity to Paclitaxel by Increasing Production of Reactive Oxygen Species in Human Ovarian Cancer Cells (HO8910)

Increasing evidence indicates that reactive oxygen species (ROS) are involved in paclitaxel cytotoxicity. Modulating the oxidant–antioxidant status of tumour cells may increase the antitumour activity of paclitaxel. The cytoprotective roles of heat shock protein 27 (HSP27) include chaperoning cellular proteins, regulating apoptotic signalling and modulating oxidative stress. Immunohistochemical staining for HSP27 in human ovarian cancer specimens showed HSP27 was associated with aggressive malignant ovarian disease. Small interfering RNA (siRNA) was used to down-regulate HSP27 in human ovarian cancer cells (HO8910). Reduction of HSP27 expression increased the in vitro chemosensitivity of HO8910 cells to paclitaxel and increased paclitaxel-induced apoptosis and ROS production, although the ROS scavenger, N-acetyl-l-cysteine, partly offset the effects of HSP27 siRNA. Thus, gene knock-down of HSP27 offsets the role of this protein in resisting oxidant stress, thereby indirectly increasing the sensitivity of cells to paclitaxel. The siRNA-induced knock-down of HSP27 could be a novel and potent strategy to help overcome chemotherapeutic resistance to paclitaxel in epithelial ovarian cancer cells.

Survivin counteracts the therapeutic effect of microtubule de-stabilizers by stabilizing tubulin polymers

Background

Survivin is a dual function protein. It inhibits the apoptosis of cells by inhibiting caspases, and also promotes cell growth by stabilizing microtubules during mitosis. Over-expression of survivin has been demonstrated to induce drug-resistance to various chemo-therapeutic agents such as cisplatin (DNA damaging agent) and paclitaxel (microtubule stabilizer) in cancers. However, survivin-induced resistance to microtubule de-stabilizers such as Vinca alkaloids and Combretastatin A-4 (CA-4)-related compounds were seldom demonstrated in the past. Furthermore, the question remains as to whether survivin plays a dominant role in processing cytokinesis or inhibiting caspases activity in cells treated with anti-mitotic compounds. The purpose of this study is to evaluate the effect of survivin on the resistance and susceptibility of human cancer cells to microtubule de-stabilizer-induced cell death.

Results

BPR0L075 is a CA-4 analog that induces microtubule de-polymerization and subsequent caspase-dependent apoptosis. To study the relationship between the expression of survivin and the resistance to microtubule de-stabilizers, a KB-derived BPR0L075-resistant cancer cell line, KB-L30, was generated for this study. Here, we found that survivin was over-expressed in the KB-L30 cells. Down-regulation of survivin by siRNA induced hyper-sensitivity to BPR0L075 in KB cells and partially re-stored sensitivity to BPR0L075 in KB-L30 cells. Western blot analysis revealed that down-regulation of survivin induced microtubule de-stabilization in both KB and KB-L30 cells. However, the same treatment did not enhance the down-stream caspase-3/-7 activities in BPR0L075-treated KB cells. Translocation of a caspase-independent apoptosis-related molecule, apoptosis-inducing factor (AIF), from cytoplasm to the nucleus was observed in survivin-targeted KB cells under BPR0L075 treatment.

Conclusion

In this study, survivin plays an important role in the stability of microtubules, but not with caspases inhibition. Over-expression of survivin counteracts the therapeutic effect of microtubule de-stabilizer BPR0L075 probably by stabilizing tubulin polymers, instead of the inhibition of caspase activity in cancer cells. Besides microtubule-related caspase-dependent cell death, caspase-independent mitotic cell death could be initiated in survivin/BPR0L075 combination treatments. We suggest that combining microtubule de-stabilizers with a survivin inhibitor may attribute to a better clinical outcome than the use of anti-mitotic monotherapy in clinical situations.

Induction of apoptosis in human hepatocarcinoma SMMC-7721 cells in vitro by flavonoids from Astragalus complanatus

AIM OF THE STUDY

Flavonoids extracted from the seeds of Astragalus complanatus R.Br. reduce the proliferation of many cancer cells. The present study was carried out to evaluate the effects of these flavonoids from Astragalus complanatus (FAC) on human hepatocarcinoma cell viability and apoptosis and to investigate its mechanisms of action in SMMC-7721 cells.

MATERIALS AND METHODS

Cell viability was measured using the MTT assay. To detect apoptotic cells, SMMC-7721 cells treated with FAC were stained with Hoechst 33258 and subjected to agarose gel electrophoresis. Quantitative detection of apoptotic cells was performed by flow cytometry. The effects of FAC on apoptosis and cell cycle regulatory genes and proteins in SMMC-7721 cells were examined using an S series apoptosis and cell cycle gene array and Western blot analysis.

RESULTS

The growth of SMMC-7721 and HepG2 cells was inhibited by treatment with FAC. Cell death induced by FAC was characterized by nuclear condensation and DNA fragmentation. Moreover, the cell cycle was arrested in the G0/G1 and S phases in FAC-treated SMMC-7721 cells. A sub-G1 peak with reduced DNA content was also formed. The activity of caspase-3 was significantly increased following FAC treatment. Microarray data indicated that the expression levels of 76 genes were changed in SMMC-7721 cells treated with FAC: 35 genes were up-regulated and 41 were down-regulated. Western blot analysis showed that caspase-3, caspase-8, Bax, P21, and P27 protein levels in SMMC-7721 cells were increased after 48 h of FAC treatment, while cyclinB1, cyclinD1, CDK1, and CDK4 protein levels were decreased.

CONCLUSIONS

These results suggest that FAC may play an important role in tumor growth suppression by inducing apoptosis in human hepatocarcinoma cells via mitochondria-dependent and death receptor-dependent apoptotic pathways.

The Role of heat shock protein 27 in extravillous trophoblast differentiation

Trophoblast cells from placental explants differentiate in culture to extravillous trophoblast cells (EVT cells). During trophoblast differentiation heat-shock-protein-27 (HSP27) mRNA and multidrug-resistance-protein-5 (MRP5, transporter of cyclic nucleotides) expression are increased. HSP27 is a regulator of actin filaments structure and dynamic, has a role in cell differentiation and may affect NF-kB activity. In this study we aimed to assess HSP27 level in trophoblast cells and its correlation with motility and differentiation related processes [MMPs activity, nitric oxide (NO), inducible nitric oxide synthase (iNOS), proliferation and MRP5 levels]. We evaluated HSP27 expression in a first trimester human trophoblast explants model designed to assess EVT cells differentiation/migration with/without 6-mercaptopurine (6MP, an EVT inhibitor of migration). We found that HSP27 level is expressed in the nucleous and cytoplasm of non-proliferting villous-trophoblast cells (negative for Ki67) and in the cell periphery and cytoplasm of motile EVT cells. Moreover, 6MP decreased HSP27 nucleous expression that was associated with inhibited MMP2 activity and NO production. Also decreased iNOS expression and increased MRP5 mRNA levels were observed. In conclusion, HSP27 expression is modulated in concordance with migration dependent parameters in trophoblast cells.

Antiproliferative effect of Erycibe elliptilimba on human breast cancer cell lines

Erycibe elliptilimba Merr. & Chun., family Convolvulaceae, is a Thai traditional medicine which has long been prescribed for various infectious and malignant diseases. Bio-assays of extracts from Erycibe elliptilimba Merr. & Chun. showed that a fraction (fraction 3) from an methanolic extract had an antiproliferative effect on SKBR3 and MDA-MB435 human breast cancer cells. The ED50 value of Erycibe elliptilimba Merr. & Chun. fraction 3 was 56.07 and 30.61 microg/ml for SKBR3 and MDA-MB435, respectively. After 48 h of exposure, this fraction at a concentration of 100 microg/ml significantly reduced cell proliferation in both cancer cells. In MDA-MB435 cells, cell cycle analysis showed that the herb extract fraction 3 induced the accumulation of cells in G2/M phase, whereas no significant change in cell cycle was detected in SKBR3 cells. The results indicated that the extract fraction 3 could induce cell cycle arrest in some way. However, further investigation is needed to assess the molecular mechanisms mediated anticancer activities of this plant.

The Proteasome Inhibitor Bortezomib Acts Independently of p53 and Induces Cell Death via Apoptosis and Mitotic Catastrophe in B-Cell Lymphoma Cell Lines

Bortezomib is a proteasome inhibitor with proven efficacy in multiple myeloma and non-Hodgkin's lymphoma. This study reports the effects of bortezomib in B-cell lymphoma cell lines with differing sensitivity to bortezomib to investigate factors that influence sensitivity. Bortezomib induced a time- and concentration-dependent reduction in cell viability in five lymphoma cell lines, with EC(50) values ranging from 6 nmol/L (DHL-7 cells) to 25 nmol/L (DHL-4 cells) after 72 h. Bortezomib cytotoxicity was independent of p53 function, as all cell lines exhibited mutations by sequence analysis. The difference in sensitivity was not explained by proteasome or nuclear factor-kappaB (NF-kappaB) inhibition as these were similar in the most and least sensitive cells. NF-kappaB inhibition was less marked than that of a specific NF-kappaB inhibitor, Bay 11-7082. Cell cycle analysis showed a marked G(2)-arrested population in the least sensitive DHL-4 line only, an effect that was not present with Bay 11-7082 treatment. Conversely, in DHL-7 cells, bortezomib treatment resulted in cells moving into an aberrant mitosis, indicative of mitotic catastrophe that may contribute to increased sensitivity to bortezomib. These studies show that although bortezomib treatment had similar effects on apoptotic and NF-kappaB signaling pathways in these cell lines, different cell cycle effects were observed and induction of a further mechanism of cell death, mitotic catastrophe, was observed in the more sensitive cell line, which may provide some pointers to the difference in sensitivity between cell lines. An improved understanding of how DHL-7 cells abrogate the G(2)-M cell cycle checkpoint may help identify targets to increase the efficacy of bortezomib.

Overexpression of heat shock protein 27 is associated with good prognosis in the patient with oral squamous cell carcinoma

We investigated the expression and biological significance of heat shock protein (HSP)-27 in patients with oral squamous cell carcinoma (SCC). The expression of HSP-27 was quantified immunohistochemically in specimens from 37 patients with oral SCC. Findings were correlated with lymph node metastases, effect of chemotherapy, and survival. The presence of HSP-27 was identified in 31 of the 37 specimens (84%). Expression was low in 4 patients (11%), intermediate in 13 (35%), and high in 14 (38%). There were significant differences in the therapeutic effect of chemotherapy (Oboshi-Shimosato's grade) and prognosis in relation to expression of HSP-27. We found no correlation between the extent of expression of HSP-27 and stage or differentiation of the tumour.

Intracellular and extracellular functions of heat shock proteins: repercussions in cancer therapy

Stress or heat shock proteins (HSPs) are the most conserved proteins present in both prokaryotes and eukaryotes. Their expression is induced in response to a wide variety of physiological and environmental insults. These proteins play an essential role as molecular chaperones by assisting the correct folding of nascent and stress-accumulated misfolded proteins, and preventing their aggregation. HSPs have a dual function depending on their intracellular or extracellular location. Intracellular HSPs have a protective function. They allow the cells to survive lethal conditions. Various mechanisms have been proposed to account for the cytoprotective functions of HSPs. Several HSPs have also been demonstrated to directly interact with various components of the tightly regulated programmed cell death machinery, upstream and downstream of the mitochondrial events. On the other hand, extracellular located or membrane-bound HSPs mediate immunological functions. They can elicit an immune response modulated either by the adaptive or innate immune system. This review will focus on HSP27, HSP70, and HSP90. We will discuss the dual role of these HSPs, protective vs. immunogenic properties, making a special emphasis in their utility as targets in cancer therapy.

Heat shock proteins: endogenous modulators of apoptotic cell death

The highly conserved heat shock proteins (Hsps) accumulate in cells exposed to heat and a variety of other stressful stimuli. Hsps, that function mainly as molecular chaperones, allow cells to adapt to gradual changes in their environment and to survive in otherwise lethal conditions. The events of cell stress and cell death are linked and Hsps induced in response to stress appear to function at key regulatory points in the control of apoptosis. Hsps include anti-apoptotic and pro-apoptotic proteins that interact with a variety of cellular proteins involved in apoptosis. Their expression level can determine the fate of the cell in response to a death stimulus, and apoptosis-inhibitory Hsps, in particular Hsp27 and Hsp70, may participate in carcinogenesis. This review summarizes the apoptosis-regulatory function of Hsps.