Treatment Of Drug-resistant Ovarian Cancer Research Articles

Diallyl trisulfide alleviates chemotherapy sensitivity of ovarian cancer via the AMPK/SIRT1/PGC1α pathway.

Platinum-based chemotherapy promotes drug resistance in ovarian cancer. We investigated the antichemoresistance characteristics of diallyl trisulfide (DATS) in cisplatin-resistant ovarian cancer cells, in vitro and in vivo. Previous preclinical studies have revealed that DATS regulates distinct hallmark cancer-signaling pathways. The cell cycle pathway is the most investigated signaling pathway in DATS. Additionally, post-DATS treatment has been found to promote proapoptotic capacity through the regulation of intrinsic and extrinsic apoptotic pathway components. In the present study, we found that treating cisplatin-sensitive and cisplatin-resistant ovarian cell lines with DATS inhibited their proliferation and reduced their IC50. It induced cell apoptosis and promoted oxidative phosphorylation through the regulation of the AMPK/SIRT1/PGC1α pathway, OXPHOS, and enhanced chemotherapy sensitivity. DATS treatment alleviated glutamine consumption in cisplatin-resistant cells. Our findings highlight the role of DATS in overcoming drug resistance in ovarian cancer in vitro and in vivo. In addition, we elucidated the role of the AMPK/SIRT1/PGC1α signaling pathway as a potential target for the treatment of drug-resistant ovarian cancer.

Ultra-small lipid carriers with adjustable release profiles for synergistic treatment of drug-resistant ovarian cancer

Multidrug resistance has dramatically compromised the effectiveness of paclitaxel (PTX). The combined application of PTX and tetrandrine (TET) is a promising avenue in drug-resistant cancer therapy. However, poor drug release and limited intracellular drug accumulation greatly impede this combinational antitumor therapy. To address this problem, we successfully developed a tunable controlled release lipid platform (PT@usNLC) for coordinated drug delivery. The drug release rate of PT@usNLC can be tuned by varying the lipid ratio, which has potential to maximize the therapeutic effects of combined drugs. The TET release rate from PT@usNLC was faster than PTX, which could restore the sensitivity of tumor cells to PTX and exert a synergistic antitumor effect. The appropriate size of PT@usNLC could effectively increase the intracellular drug accumulation. Both in vitro and in vivo studies revealed that PT@usNLC significantly enhanced the therapeutic effect compared to conventional therapies. This study provides a new strategy for resistant ovarian cancer therapy.

Radix ranunculus temate saponins sensitizes ovarian cancer to Taxol via upregulation of miR-let-7b.

A common cause of treatment failure in ovarian cancer is acquired drug resistance. Therefore, effective novel drugs against chemoresistance need to be developed. MicroRNAs (miRNAs or miRs) serve key regulatory roles in tumorigenesis and chemoresistance. The objective of the present study was to explore the role of miR-let-7b in ovarian cancer chemoresistance, and to develop novel strategy for the treatment of drug-resistant ovarian cancer. For this purpose, reverse transcription-quantitative PCR was performed to evaluate the expression level of miR-let-7b in fresh ovarian cancer tissues and cell lines. miR-let-7b mimic was transfected into ovarian cancer cell lines. Functional experiments, cell apoptosis and cell viability assays were carried out to identify the tumor-suppressor function of miR-let-7b. The treatment effect of Radix ranunculus temate saponins (RRTS), one of the primary constituents extracted from the traditional Chinese medicine radix Ranunculi ternati, was identified in vitro and in vivo. The results revealed that miR-let-7b was downregulated significantly in chemoresistant ovarian cancer patients. miR-let-7b overexpression suppressed cell growth and invasion and enhanced sensitivity to Taxol of ovarian cancer cells. Furthermore, miR-let-7b levels in ovarian cancer tissue were inversely associated with collagen type III α1 chain (COL3A1) levels. COL3A1, a non-fibrillar collagen associated with chemoresistance, was targeted by miR-let-7b. RRTS showed cytotoxic effects on ovarian cancer cells through inducing miR-let-7b expression and decreasing COL3A1 expression. In addition, RRTS sensitized ovarian cancer to Taxol both in vitro and in vivo. In conclusion, the present results revealed synergistic cytotoxicity of RRTS and Taxol on against ovarian cancer cells via upregulating expression of miR-let-7b. Combination of Taxol and RRTS may be a novel treatment strategy for patients with TR ovarian cancer.

Dietary geranylgeraniol can limit the activity of pitavastatin as a potential treatment for drug-resistant ovarian cancer

Pre-clinical and retrospective studies of patients using statins to reduce plasma cholesterol have suggested that statins may be useful to treat cancer. However, prospective clinical trials have yet to demonstrate significant efficacy. We have previously shown that this is in part because a hydrophobic statin with a long half-life is necessary. Pitavastatin, the only statin with this profile, has not undergone clinical evaluation in oncology. The target of pitavastatin, hydroxymethylglutarate coenzyme-A reductase (HMGCR), was found to be over-expressed in all ovarian cancer cell lines examined and upregulated by mutated TP53, a gene commonly altered in ovarian cancer. Pitavastatin-induced apoptosis was blocked by geranylgeraniol and mevalonate, products of the HMGCR pathway, confirming that pitavastatin causes cell death through inhibition of HMGCR. Solvent extracts of human and mouse food were also able to block pitavastatin-induced apoptosis, suggesting diet might influence the outcome of clinical trials. When nude mice were maintained on a diet lacking geranylgeraniol, oral pitavastatin caused regression of Ovcar-4 tumour xenografts. However, when the animal diet was supplemented with geranylgeraniol, pitavastatin failed to prevent tumour growth. This suggests that a diet containing geranylgeraniol can limit the anti-tumour activity of pitavastatin and diet should be controlled in clinical trials of statins.

Abstract 4115: Combination of FTY720 and tamoxifen inhibits drug-resistant ovarian cancer cell proliferation

Abstract Despite satisfactory initial responses to frontline therapies that combine surgical debulking with platinum based chemotherapy, virtually all women with advanced ovarian cancer relapse with drug resistant disease. There is a critical need to identify alternative, effective therapies. Previously, we used patient derived xenograft (PDX) models of ovarian cancer in mice to identify the sphingosine1 phosphate (S1P) pathway as one of the pathways most affected by two agents frequently used to treat ovarian cancer, carboplatin and paclitaxel. The S1P pathway contributes to multiple biological processes recognized as essential for tumor development, and aberrations in sphingolipid metabolism have been directly correlated with advanced disease and with resistance to chemotherapy and radiation. Further, recent studies indicate that tamoxifen may counteract drug resistance mechanisms through modulation of sphingolipid metabolism, specifically through inhibition of the ceramide converting enyzmes acid ceramidase and glucosylceramide synthase. Therefore, we evaluated the efficacy of modulating S1P metabolism using the sphingosine analog FTY720 and tamoxifen as an approach to inhibit the proliferation of drug-resistant ovarian tumor cells. We used alamarBlue cell proliferation assays to compare the anti-proliferative effect of FTY720 and tamoxifen with the effect of each drug as a single agent. FTY720 + tamoxifen synergistically decreased the cell viability of 3/3 ovarian cancer cell lines: estrogen receptor alpha (ERα) positive SKOV3.TR (taxane resistant), ERα negative A280.cp20 (platinum resistant) and HeyA8.MDR (taxane-platinum resistant). The combination also increased levels of apoptosis as reflected by Annexin V staining and cleaved caspase 3 levels. Further, administration of 5mg/kg i.p. FTY720 + 20mg/kg p.o. tamoxifen daily for 21 days to PDX-bearing mice demonstrated that FTY720 + tamoxifen suppressed tumor growth by ~60% compared to vehicle controls. Notably, immunohistochemical staining of tumors harvested from treated mice showed that the combination decreased expression of the proliferation marker Ki-67 and increased expression of apoptosis indicators ceramide and cleaved caspase 3 to a greater degree than in tumors exposed to either drug alone. We conclude that FTY720 + tamoxifen merit further investigation as potentially effective agents for the treatment of drug-resistant ovarian cancer. Citation Format: Kelly Marie Kreitzburg, Charles N. Landen, Tracy Gamblin, Rebecca Arend, Ronald Alvarez, Karina Yoon. Combination of FTY720 and tamoxifen inhibits drug-resistant ovarian cancer cell proliferation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4115. doi:10.1158/1538-7445.AM2017-4115

835 - Pitavastatin is a potential treatment for drug-resistant ovarian cancer

835 - Pitavastatin is a potential treatment for drug-resistant ovarian cancer

Reprogramming antitumor immunity against chemoresistant ovarian cancer by a CXCR4 antagonist-armed viral oncotherapy

Ovarian cancer remains the most lethal gynecologic malignancy owing to late detection, intrinsic and acquired chemoresistance, and remarkable heterogeneity. Here, we explored approaches to inhibit metastatic growth of murine and human ovarian tumor variants resistant to paclitaxel and carboplatin by oncolytic vaccinia virus expressing a CXCR4 antagonist to target the CXCL12 chemokine/CXCR4 receptor signaling axis alone or in combination with doxorubicin. The resistant variants exhibited augmented expression of the hyaluronan receptor CD44 and CXCR4 along with elevated Akt and ERK1/2 activation and displayed an increased susceptibility to viral infection compared with the parental counterparts. The infected cultures were more sensitive to doxorubicin-mediated killing both in vitro and in tumor-challenged mice. Mechanistically, the combination treatment increased apoptosis and phagocytosis of tumor material by dendritic cells associated with induction of antitumor immunity. Targeting syngeneic tumors with this regimen increased intratumoral infiltration of antitumor CD8+ T cells. This was further enhanced by reducing the immunosuppressive network by the virally-delivered CXCR4 antagonist, which augmented antitumor immune responses and led to tumor-free survival. Our results define novel strategies for treatment of drug-resistant ovarian cancer that increase immunogenic cell death and reverse the immunosuppressive tumor microenvironment, culminating in antitumor immune responses that control metastatic tumor growth.

Decitabine Enhances Lymphocyte Migration and Function and Synergizes with CTLA-4 Blockade in a Murine Ovarian Cancer Model.

The lack of second-line treatment for relapsed ovarian cancer necessitates the development of improved combination therapies. Targeted therapy and immunotherapy each confer clinical benefit, albeit limited as monotherapies. Ovarian cancer is not particularly responsive to immune checkpoint blockade, so combination with a complementary therapy may be beneficial. Recent studies have revealed that a DNA methyl transferase inhibitor, azacytidine, alters expression of immunoregulatory genes in ovarian cancer. In this study, the antitumor effects of a related DNA methyl transferase inhibitor, decitabine (DAC), were demonstrated in a syngeneic murine ovarian cancer model. Low-dose DAC treatment increases the expression of chemokines that recruit NK cells and CD8(+) T cells, promotes their production of IFNγ and TNFα, and extends the survival of mice bearing subcutaneous or orthotopic tumors. While neither DAC nor immune checkpoint blockade confers durable responses as a monotherapy in this model, the efficacy of anti-CTLA-4 was potentiated by combination with DAC. This combination promotes differentiation of naïve T cells into effector T cells and prolongs cytotoxic lymphocyte responses as well as mouse survival. These results suggest that this combination therapy may be worthy of further consideration for improved treatment of drug-resistant ovarian cancer.

Abstract 3587: Developing targeted therapy for the treatment of drug-resistant ovarian cancer

Abstract Despite therapeutic approaches that combine surgical cytoreduction with chemotherapy, ovarian cancer remains the principal cause of death among women with gynecological malignancies. Virtually all patients relapse with drug-resistant disease. To elucidate the biological mechanisms that contribute to this resistance, we established a repository of patient-derived xenograft (PDX) models of ovarian cancer in mice. We used RNA-seq and Ingenuity Canonical Pathway software to analyze chemotherapy induced changes in expression patterns of six of these models. We found that the sphingosine-1-phosphate (S1P) signaling pathway is one of the pathways most affected by paclitaxel and cisplatin treatment, with altered expression in seven genes associated with the S1P pathway (p<0.05). The biologically active lipid S1P contributes to cell growth, survival/apoptosis, angiogenesis, migration and metastasis in normal and tumor tissue. The S1P pathway has also been reported to be involved in chemoresistance in several types of solid tumors. The S1P pathway depends predominately on three core lipids: ceramide, sphingosine, and S1P. These molecules are termed the ceramide-sphingosine-S1P rheostat, and their expression is tightly regulated both intra- and extra-cellularly. Recent studies suggest a correlation between aberrations in the S1P pathway and poor prognosis, advanced stage, and resistance to chemotherapy and radiation. Preliminary data using the sphingosine analog FTY-720 is consistent with the hypothesis that the S1P pathway regulates cell survival by effecting changes in the relative levels of ceramide, sphingosine, and S1P, as a cytoprotective autophagic mechanism to evade chemotherapy-induced cytotoxic effects. Cell proliferation assays, immunoblots, and fluorescence microscopy results of ovarian cancer cells exposed to FTY-720 in combination with carboplatin or paclitaxel treatment provide evidence that the S1P pathway may evade cell death through the induction of cytoprotective autophagy. Our data suggest that the S1P pathway contributes to the chemoresistance of ovarian cancer cells to conventional chemotherapeutic agents. Citation Format: Kelly M. Kreitzburg, Zacchary Dobbins, Ashwini Katre, Tooba Anwer, Ronald Alvarez, Charles N. Landen, Karina J. Yoon. Developing targeted therapy for the treatment of drug-resistant ovarian cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3587. doi:10.1158/1538-7445.AM2015-3587

Down-regulation of Ras-related Protein Rab 5C-dependent Endocytosis and Glycolysis in Cisplatin-resistant Ovarian Cancer Cell Lines

Drug resistance poses a major challenge to ovarian cancer treatment. Understanding mechanisms of drug resistance is important for finding new therapeutic targets. In the present work, a cisplatin-resistant ovarian cancer cell line A2780-DR was established with a resistance index of 6.64. The cellular accumulation of cisplatin was significantly reduced in A2780-DR cells as compared with A2780 cells consistent with the general character of drug resistance. Quantitative proteomic analysis identified 340 differentially expressed proteins between A2780 and A2780-DR cells, which involve in diverse cellular processes, including metabolic process, cellular component biogenesis, cellular processes, and stress responses. Expression levels of Ras-related proteins Rab 5C and Rab 11B in A2780-DR cells were lower than those in A2780 cells as confirmed by real-time quantitative PCR and Western blotting. The short hairpin (sh)RNA-mediated knockdown of Rab 5C in A2780 cells resulted in markedly increased resistance to cisplatin whereas overexpression of Rab 5C in A2780-DR cells increases sensitivity to cisplatin, demonstrating that Rab 5C-dependent endocytosis plays an important role in cisplatin resistance. Our results also showed that expressions of glycolytic enzymes pyruvate kinase, glucose-6-phosphate isomerase, fructose-bisphosphate aldolase, lactate dehydrogenase, and phosphoglycerate kinase 1 were down-regulated in drug resistant cells, indicating drug resistance in ovarian cancer is directly associated with a decrease in glycolysis. Furthermore, it was found that glutathione reductase were up-regulated in A2780-DR, whereas vimentin, HSP90, and Annexin A1 and A2 were down-regulated. Taken together, our results suggest that drug resistance in ovarian cancer cell line A2780 is caused by multifactorial traits, including the down-regulation of Rab 5C-dependent endocytosis of cisplatin, glycolytic enzymes, and vimentin, and up-regulation of antioxidant proteins, suggesting Rab 5C is a potential target for treatment of drug-resistant ovarian cancer. This constitutes a further step toward a comprehensive understanding of drug resistance in ovarian cancer.

Multifunctional nanomedicine platform for concurrent delivery of chemotherapeutic drugs and mild hyperthermia to ovarian cancer cells

A multifunctional tumor-targeting delivery system was developed and evaluated for an efficient treatment of drug-resistant ovarian cancer by combinatorial therapeutic modality based on chemotherapy and mild hyperthermia. The engineered iron oxide nanoparticle (IONPs)-based nanocarrier served as an efficient delivery vehicle for doxorubicin and provided the ability to heat cancer cells remotely upon exposure to an alternating magnetic field (AMF). The nanocarrier was additionally modified with polyethylene glycol and LHRH peptide to improve its biocompatibility and ability to target tumor cells. The synthesized delivery system has an average size of 97.1 nm and a zeta potential close to zero, both parameters favorable for increased stability in biological media and decreased elimination by the immune system. The nanocarrier demonstrated faster drug release in acidic conditions that mimic the tumor environment. It was also observed that the LHRH targeted delivery system could effectively enter drug resistant ovarian cancer cells, and the fate of doxorubicin was tracked with fluorescence microscope. Mild hyperthermia (40°C) generated by IONPs under exposure to AMF synergistically increased the cytotoxicity of doxorubicin delivered by the developed nanocarrier to cancer cells. Thus, the developed IONPs-based delivery system has high potential in the effective treatment of ovarian cancer by combinatorial approach.

Inhibition of mortalin expression reverses cisplatin resistance and attenuates growth of ovarian cancer cells

The heat shock protein mortalin is frequently overexpressed in human malignancies. In this study, an assessment of mortalin expression using ovarian cancer tissue microarrays suggested that mortalin overexpression might be related to drug resistance. Using a short hairpin (sh) RNA approach, we evaluated the effect of reducing mortalin expression in vitro and in vivo. The results of our study show that elevated levels of mortalin expression increase cancer cell resistance to cisplatin-induced cytotoxicity and identify mortalin as a potential therapeutic target for improved treatment of drug-resistant ovarian cancer.

1040 Polyarsenic Adamantane-type Compounds – a Promising New Class of Drugs for the Treatment of Drug-resistant Ovarian Cancers

1040 Polyarsenic Adamantane-type Compounds – a Promising New Class of Drugs for the Treatment of Drug-resistant Ovarian Cancers

Chemotherapy resistance induced by interleukin-6 in ovarian cancer cells and its signal transduction pathways

To study the mechanism of chemotherapy resistance caused by interleukin-6 (IL-6) in ovarian cancer cells and its related signal pathways. Ovarian cancer cell lines A2780 (IL-6 receptor positive, while non-IL-6-expressing and cisplatin/paclitaxel-responsive) and SKOV3 cell lines (overexpressing of IL-6 receptor and IL-6 and cisplatin/paclitaxel-resistant) were suitable models for this study. The effect of exogenous (a short period of treatment with recombination IL-6) and endogenous IL-6 (by transfecting with plasmid encoding for sense IL-6) in A2780 cells or deleting of endogenous IL-6 expression in SKOV3 cells (by transfecting with plasmid encoding for antisense IL-6) on the sensitivity to cisplatin and paclitaxel was investigated. Meanwhile, the mechanism of chemotherapy resistance caused by IL-6 in ovarian cancer cells and its related signal pathways were also analyzed. We found that both exogenous and endogenous IL-6 induce cisplatin and paclitaxel resistance in non-IL-6-expressing A2780 cells (the resistance multiple to cisplatin and paclitaxel was: exogenous, 6.25 and 7.31; endogenous, 7.13-8.34 and 7.61-10.70), while deleting of endogenous IL-6 expression in IL-6-overexpressing SKOV3 cells promotes its sensitivity to anticancer drugs (the resistance multiple to cisplatin and paclitaxel was 0.15 and 0.10, 0.10 and 0.08). IL-6 significantly up-regulated the expression levels of mRNA and protein of drug resistance-associated genes, MDR1 and GST-π, and apoptosis-inhibiting genes, bcl-2, bcl-xL and XIAP in a dose-dependent manner in A2780 cells. In accordance with this finding, the mRNA and protein levels of MDR1 and GST-π enhanced in sense IL-6-transfected A2780 cells, and reduced in antisense IL-6-transfected SKOV3 cells compared with the corresponding parental and control vector-transfected cells, which had no difference. It was found that PD98059 [mitogen-activated protein kinase-extracellular signal-regulated kinase (MEK) inhibitor] and wortmannin [phosphatidylinositol 3-kinase (PI3K) inhibitor] significantly antagonized IL-6-induced phosphorylation of extracellular signal-regulated kinase (ERK) and protein kinase B (Akt), respectively, and both of them blocked IL-6-induced cisplatin and paclitaxel resistance and the inhibitory effects of PD98059 and wortmannin were dependent on its concentration. These data suggest that IL-6-induced chemoresistance may be associated with increase of both drug resistance-associated genes (MDR1 and GST-π) and apoptosis-inhibiting genes (bcl-2, bcl-xL and XIAP), and activation of MEK/ERK and PI3K/Akt. Therefore, modulation of IL-6 expression or its related signaling pathway may be a promising strategy of treatment for drug-resistant ovarian cancer.

Autocrine production of interleukin-6 confers cisplatin and paclitaxel resistance in ovarian cancer cells

It has been shown that IL-6 is elevated in the serum and ascites of ovarian cancer patients, and increased IL-6 concentration correlates with poor prognosis and chemoresistance. However, the role of IL-6 expression in the acquisition of the chemoresistance phenotype and the underlining mechanisms of drug resistance in ovarian cancer cells remain unclear. Here we demonstrate that both exogenous (a relatively short period of treatment with recombination IL-6) and endogenous IL-6 (by transfecting with plasmid encoding for sense IL-6) induce cisplatin and paclitaxel resistance in non-IL-6-expressing A2780 cells, while deleting of endogenous IL-6 expression in IL-6-overexpressing SKOV3 cells (by transfecting with plasmid encoding for antisense IL-6) promotes the sensitivity of these cells to anticancer drugs. IL-6-mediated resistance of ovarian cancer cells exhibits decreased proteolytic activation of caspase-3. Meanwhile, the further study demonstrates that the chemoresistance caused by IL-6 is associated with increased expression of both multidrug resistance-related genes (MDR1 and GSTpi) and apoptosis inhibitory proteins (Bcl-2, Bcl-xL and XIAP), as well as activation of Ras/MEK/ERK and PI3K/Akt signaling. Therefore, modulation of IL-6 expression or its related signaling pathway may be a promising strategy of treatment for drug-resistant ovarian cancer.

Sensitization of ovarian cancer cells to cisplatin by genistein: the role of NF-kappaB

BackgroundPlatinum-resistance (PR) continues to be a major problem in the management of epithelial ovarian cancer (EOC). Response to various chemotherapeutic agents is poor in patients deemed PR. Genistein, a soy isoflavone has been shown to enhance the effect of chemotherapy in prostate and pancreatic cancer cells in vitro and in vivo by reversing chemo-resistance phenotype. The goal of this study was to investigate the effects of combination therapy with genistein and cisplatin as well as other cytotoxic conventional chemotherapeutic agents in platinum-sensitive (PS) and resistant EOC cells.MethodsThe PS human ovarian cancer cell line A2780 and its PR clone C200 cells were pretreated with genistein, followed by the combination of genistein and either cisplatin, taxotere or gemcitabine. Cell survival and apoptosis was assessed by MTT and histone-DNA ELISA. Electrophoretic mobility shift assay (EMSA) was used to evaluate NF-κB DNA binding activity. Western blot analysis was performed with antibodies to Bcl-2, Bcl-xL, survivin, c-IAP and PARP.ResultsReduction in cell viability, and corresponding induction of apoptosis was observed with genistein pretreatment followed by combination treatment with each of the drugs in both cell lines. The PS cell line was pretreated for 24 hours; in contrast, the PR cell line required 48 hours pretreatment to achieve a response. The anti-apoptotic genes c-IAP1, Bcl-2, Bcl-xL, survivin and NF-κB DNA binding activity were all found to be down-regulated in the combination groups.ConclusionThis study convincingly demonstrated that the current strategy can be translated in a pre-clinical animal model, and thus it should stimulate future clinical trial for the treatment of drug-resistant ovarian cancer.

Correction to “Development of a Novel Nitro-Derivative of Noscapine for the Potential Treatment of Drug-Resistant Ovarian Cancer and T-Cell Lymphoma”

Correction to “Development of a Novel Nitro-Derivative of Noscapine for the Potential Treatment of Drug-Resistant Ovarian Cancer and T-Cell Lymphoma”

Development of a Novel Nitro-Derivative of Noscapine for the Potential Treatment of Drug-Resistant Ovarian Cancer and T-Cell Lymphoma

We have shown previously that an antitussive plant alkaloid, noscapine, binds tubulin, displays anticancer activity, and has a safe pharmacological profile in humans. Structure-function analyses pointed to a proton at position-9 of the isoquinoline ring that can be modified without compromising tubulin binding activity. Thus, many noscapine analogs with different functional moieties at position-9 were synthesized. Those analogs that kill human cancer cells resistant to other antimicrotubule agents, vincas and taxanes, were screened. Here, we present one such analog, 9-nitro-noscapine (9-nitro-nos), which binds tubulin and induces apoptosis selectively in tumor cells (ovarian and T-cell lymphoma) resistant to paclitaxel, vinblastine, and teniposide. 9-Nitro-nos treatment at doses as high as 100 microM did not affect the cell cycle profile of normal human fibroblasts. This selectivity of 9-nitro-nos for cancer cells represents a unique edge over the other available antimitotics. 9-Nitro-nos perturbs the progression of cell cycle by mitotic arrest, followed by apoptotic cell death associated with increased caspase-3 activation and appearance of terminal deoxynucleotidyl transferase dUTP nick-end labeling-positive cells. Thus, we conclude that 9-nitro-nos has great potential to be a novel therapeutic agent for ovarian and T-cell lymphoma cancers, even those that have become drug-resistant to currently available chemotherapeutic drugs.

Ultrastructure alterations in adriamycin-resistant and cisplatin-resistant human ovarian cancer cell lines exposed to nonlethal ultrasound

Human ovarian cancer cell lines, SKOV3 and its adriamycin-resistant substrain SKOV3/ADR and COC1 and its cisplatin-resistant substrain COC1/DDP, were exposed to nonlethal ultrasound. Ultrastructures in sham-insonated and insonated cells were inspected by transmission electron microscopy, and cytochrome C in cytosol was determined by enzyme-linked immunosorbent assay. Ultrasound exposure led to no significant changes in SKOV3/ADR cells, but tumid mitochondria occurred in SKOV3 cells. Mitochondria changes were also detected in some exposed COC1 and COC1/DDP cells. Apoptotic bodies could be detected in either control or insonated COC1/DDP cells. A few exposed COC1/DDP cells became reticular. Cytochrome C in cytosol in exposed SKOV3/ADR cells was increased but that in exposed COC1/DDP cells was decreased. These findings revealed that the bioeffect of ultrasound on chemosensitive cells was not identical to that of chemoresistant ones, and ultrasound was a potential approach for treatment of drug-resistant ovarian cancers.

Ultrastructure alterations in adriamycin-resistant and cisplatin-resistant human ovarian cancer cell lines exposed to nonlethal ultrasound

Human ovarian cancer cell lines, SKOV3and its adriamycin-resistant substrain SKOV3/ADR and COC1 and its cisplatin-resistant substrain COC1/DDP, were exposed to nonlethal ultrasound. Ultrastructures in sham-insonated and insonated cells were inspected by transmission electron microscopy, and cytochrome C in cytosol was determined by enzyme-linked immunosorbent assay. Ultrasound exposure led to no significant changes in SKOV3/ADR cells, but tumid mitochondria occurred in SKOV3cells. Mitochondria changes were also detected in some exposed COC1 and COC1/DDP cells. Apoptotic bodies could be detected in either control or insonated COC1/DDP cells. A few exposed COC1/DDP cells became reticular. Cytochrome C in cytosol in exposed SKOV3/ADR cells was increased but that in exposed COC1/DDP cells was decreased. These findings revealed that the bioeffect of ultrasound on chemosensitive cells was not identical to that of chemoresistant ones, and ultrasound was a potential approach for treatment of drug-resistant ovarian cancers.