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Cellular resistance to platinum anticancer compounds is governed by no less than two molecular processes; DNA repair and cellular accumulation of drug. Gli1 is an upstream regulator of nucleotide excision repair, effecting this process through c-jun. We, therefore, investigated whether Gli1 plays a role in cellular accumulation of cisplatin. Using a Gli1-specific shRNA, we explored the role of Gli1 in the cellular accumulation and efflux of cisplatin, in cisplatin-resistant A2780-CP70 human ovarian cancer cells. When Gli1 is inhibited, cellular uptake of cisplatin was approximately 33% of the level of uptake under control conditions. When Gli1 is inhibited, cellular efflux of cisplatin was completely abrogated, over a 12-h period of observation. We assayed nuclear lysates from these cells, for the ability to bind the DNA sequence that is the Gli-binding site (GBS) in the 5'UTR for each of five known cisplatin transmembrane transporters. Four of these transporters are active in cisplatin uptake; and, one is active in cisplatin efflux. In each case, nuclear lysate from A2780-CP70 cells binds the GBS of the respective cisplatin transport gene. We conclude that Gli1 plays a strong role in total cellular accumulation of cisplatin in these cells; and, that the combined effects on cellular accumulation of drug and on DNA repair may indicate a role for Gli1 in protecting cellular DNA from lethal types of DNA damage.

Background: Triple-negative breast cancer (TNBC) is a highly diverse group that is associated with an aggressive phenotype. Its treatment has been challenging due to its heterogeneity and absence of well-defined molecular targets. Thus, there is an urgent need to identify novel agents with therapeutic application. NF-κB is over-expressed in many breast cancers; thus, inactivation of the NF-κB pathway could serve as a therapeutic target. Here we report for the first time the anti-tumor activity of panepoxydone (PP), a NF-κB inhibitor isolated from an edible mushroom, in several breast cancer cell lines., Methods: We investigated the effects of PP on cell growth, migration-invasion, apoptosis and EMT-related proteins expression in MCF-7 and TNBC cell lines MDA-MB-231, MDA-MB-468 and MDA-MB-453., Results: Significant antitumor activity was seen in all cell lines, with differential responses noted in cell-line specific manner. Treatment with PP resulted in significant cytotoxicity, decreased invasion, migration and increased apoptosis in all cell lines tested. Up-regulation of Bax and cleaved PARP and down-regulation of Bcl-2, survivin, cyclin D1 and caspase 3 were noted in PP-treated breast cancer cells. The antitumor effect of PP appeared related to its ability to inhibit the phosphorylation of inhibitor of NF-κB (IκBα) with cytoplasmic accumulation. PP treatment also down-regulated FOXM1 which resulted in a reversal of EMT. Similar results were obtained after silencing of NF-kB and FOXM1., Conclusion: Altogether, these studies show, for the first time the antitumor activity of PP against breast cancer cells, in particular TNBC cells. Furthermore, it highlights the concept that optimal treatment of TNBC warrants attention to the differential sensitivity of various TNBC subtypes to therapeutic agents. These results suggest that the PP may be a potentially effective chemopreventive or therapeutic agent against breast cancer. However, additional studies are required to more fully elucidate the mechanism of antitumor effect of PP.

Cisplatin-based combination treatment is the most effective systemic chemotherapy for bladder cancer; however, resistance to cisplatin remains a significant problem in the treatment of this disease. β-Elemene is a new natural compound that blocks cell-cycle progression and has a broad spectrum of antitumor activity. This study was conducted to explore the potential of β-elemene as a chemosensitizer for enhancing the therapeutic efficacy and potency of cisplatin in bladder cancer and other solid carcinomas. β-Elemene not only markedly inhibited cell growth and proliferation but also substantially increased cisplatin cytotoxicity towards human bladder cancer 5637 and T-24 cells. Similarly, β-elemene also enhanced cisplatin sensitivity and augmented cisplatin cytotoxicity in small-cell lung cancer and carcinomas of the brain, breast, cervix, ovary, and colorectal tract in vitro, with dose-modifying factors ranging from 5 to 124. β-Elemene-enhanced cisplatin cytotoxicity was associated with increased apoptotic cell death, as determined by DNA fragmentation, and increased activities of caspase-3, -7, -8, -9, and -10 in bladder cancer cell lines. Collectively, these results suggest that β-elemene augments the antitumor activity of cisplatin in human bladder cancer by enhancing the induction of cellular apoptosis via a caspase-dependent mechanism. Cisplatin combined with β-elemene as a chemosensitizer warrants further pre-clinical therapeutic studies and may be useful for the treatment of cisplatin-resistant bladder cancer and other types of carcinomas.

β-Elemene is a new anticancer compound extracted from the Chinese medicinal herb Rhizoma zedoariae. We have shown previously that β-elemene increases cisplatin cytotoxicity and enhances cisplatin sensitivity via blocking cell cycle progression at G2/M phase in resistant ovarian tumor cells. In the current study, we asked whether β-elemene-augmented cisplatin activity in ovarian carcinoma cells is mediated through the induction of apoptosis. Here, we show that β-elemene triggered apoptotic cell death in chemoresistant human ovarian cancer A2780/CP and MCAS cells in a dose- and time-dependent fashion, as assessed by six different apoptosis assays. Intriguingly, β-elemene was a stronger inducer of apoptosis than cisplatin in this model system, and a synergistic effect on induction of cell death was observed when the tumor cells were treated with both agents. Furthermore, β-elemene plus cisplatin exposure significantly disrupted the mitochondrial transmembrane potential (ΔΨ (m)) and increased the release of cytochrome c from mitochondria into the cytoplasm. The combination treatment with both compounds also induced increases in caspase-3/8/9 activities and caspase-9 cleavage, enhanced protein expression of Bax and phosphorylation of Bcl-2 at Ser-70, and reduced the protein levels of Bcl-2 and Bcl-X(L) in the platinum-resistant ovarian cancer cells. Taken together, these data indicate that β-elemene sensitizes chemoresistant ovarian carcinoma cells to cisplatin-induced apoptosis and that the augmented effect of β-elemene on cisplatin cytotoxicity and sensitivity in resistant ovarian tumor cells is mediated through a mitochondria- and caspase-dependent cell death pathway.

The development of cisplatin drug resistance remains a chief concern in ovarian cancer chemotherapy. β-Elemene is a natural plant product with broad-spectrum antitumor activity towards many types of carcinomas. This study aimed to define the biological and therapeutic significance of β-elemene in chemoresistant ovarian cancer. In the present study, β-elemene significantly inhibited cell growth and proliferation of both the cisplatin-sensitive human ovarian cancer cell line A2780 and its cisplatin-resistant counterpart A2780/CP. β-Elemene also suppressed the growth of several other chemosensitive and chemoresistant ovarian cancer cell lines, including ES-2, MCAS, OVCAR-3, and SKOV-3, with the half maximal inhibitory concentration (IC(50)) values ranging from 54 to 78 μg/ml. In contrast, the IC(50) values of β-elemene for the human ovarian epithelial cell lines IOSE-386 and IOSE-397 were 110 and 114 μg/ml, respectively, which are almost two-fold those for the ovarian cancer cell lines. Cell cycle analysis demonstrated that β-elemene induced a persistent block of cell cycle progression at the G(2)/M phase in A2780 and A2780/CP cells. This was mediated by alterations in cyclin and cyclin-dependent kinase expression, including the down-regulation of CDC2, cyclin A, and cyclin B1, and the up-regulation of p21(WAF1/CIP1) and p53 proteins. Moreover, β-elemene triggered apoptosis and irreversible cell death in both sensitive and resistant ovarian cancer cells via the activation of caspase-3, -8 and 9; the loss of mitochondrial membrane potential (δΨm); the release of cytochrome c into the cytosol; and changes in the expression of BCL-2 family proteins. All of these molecular changes were associated with β-elemene-induced growth inhibition and cell death of ovarian cancer cells. Our results demonstrate that β-elemene has antitumor activity against both platinum-sensitive and resistant ovarian cancer cells, and thus has the potential for development as a chemotherapeutic agent for cisplatin-resistant ovarian cancer.

Genetic polymorphisms in ERCC1 are thought to contribute to altered sensitivity to platinum-based chemotherapy. Although ERCC1 N118N (500 C>T, rs11615) is the most studied polymorphism, the impact of this polymorphism on platinum-based chemotherapy remains unclear. This is the first study in which the functional impact of ERCC1 N118N on gene expression and platinum sensitivity was explored. The aim of this study is to investigate if the reduced codon usage frequency of AAT, which contains the variant allele of the silent mutation, has functional impact on ERCC1 in a well-controlled biological system. Specifically, the ERCC1 cDNA clone with either the C or T allele was introduced into an ERCC1 deficient cell line, UV20, and assayed for the effect of the two alleles on ERCC1 transcription, translation and platinum sensitivity. Both ERCC1 mRNA and protein expression levels increased upon cisplatin treatment, peaking at 4h post-treatment, however there were no differences between the two alleles (p>0.05). Cells complemented with ERCC1 showed significantly higher survival proportion than the parental cell line following platinum exposure (p<0.0001), although no differences were observed between the cells transfected with the wild type or the polymorphic allele. These data suggest that N118N itself is not related to the phenotypic differences in ERCC1 expression or function, but rather this polymorphism may be linked to other causative variants or haplotypes., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Beta-elemene has recently raised interest in P.R. China as a novel antitumor plant drug isolated from the Chinese medicinal herb Zedoary. To explore potentially useful combinations of beta-elemene with taxanes in the clinic, we characterized the effects of beta-elemene combined with taxanes in human lung cancer cells using a median effect analysis, micronucleus assay, apoptotic detection, and determination of gene expression in the signaling pathways of apoptosis. The synergistic analysis indicated that the interactions of beta-elemene with paclitaxel or docetaxel ranged from slight synergism to synergism. Combinations of beta-elemene with docetaxel induced much stronger synergistic interactions in p53 mutant H23 cells and p53 null H358 cells than in p53 wild-type H460 and A549 cells. Similar synergistic interactions were observed by micronucleus assay, apoptotic detection, and determination of apoptotic gene expression. Our findings indicate that the synergistic effects achieved with combinations of beta-elemene and taxanes are related to the augmented cytotoxic efficacy of taxanes owing to the action of beta-elemene. In H460 and A549 cells, dose-dependent upregulation of p53 protein expression was observed in cultures treated with docetaxel alone and with docetaxel plus beta-elemene, whereas no significant change in p53 expression was observed in any of the treatment groups in H23 cells. Fas revealed no alteration of expression with any of the treatments in this study. However, the combination treatments induced increased cytochrome c release from mitochondria, significant caspase-8 and -3 cleavage, and downregulation of Bcl-2 and Bcl-XL expression. These results suggest that, although p53 plays an important role in taxane-induced cell death, apoptosis induced by beta-elemene or in combination with docetaxel thereof seems to be initiated through a p53- and Fas-independent pathway via mitochondria in our lung cancer cells. The suppression of specific 'survival' gene expression appears to be the key action leading to the synergistic effect of combination treatments with beta-elemene and taxanes. Finally, the beta-elemene-induced alteration of cell membrane permeability, which has potential to result in enhanced cellular uptake of taxanes, may also contribute to the synergistic interactions of the combination treatments.

The biology of vascular endothelium can be modulated through the use of pharmacologic agents. Whereas this has been explored to reasonable extent in cardiovascular disease, it is clear that the ability to modulate vascular endothelium for the purpose of cancer prevention is in its early stages. Among the unanswered questions, we do not understand under what circumstances such pharmacologic interventions might best be started; nor, how long such interventions might be used for a given individual. We present concepts for further exploration in the use of endothelial-active agents for cancer prevention and control; and, strategies for public health practice and research in this area.

Tumor suppressor gene BRCA1 is frequently mutated in familial breast and ovarian cancer. BRCA1 plays pivotal roles in maintaining genomic stability by interacting with numerous proteins in cell cycle control and DNA repair. Irofulven (6-hydroxymethylacylfulvene, HMAF, MGI 114, NSC 683863) is one of a new class of anticancer agents that are analogs of mushroom-derived illudin toxins. Preclinical studies and clinical trials have demonstrated that irofulven is effective against several tumor cell types. The exact nature of irofulven-induced DNA damage is not completely understood. We demonstrated previously that irofulven activates ATM and its targets, NBS1, SMC1, CHK2, and p53. In this study, we hypothesize that irofulven induces DNA double-strand breaks and that BRCA1 may affect chemosensitivity by controlling cell cycle checkpoints, DNA repair, and genomic stability in response to irofulven treatment. We observed that irofulven induces the formation of chromosome breaks and radials and the activation and foci formation of gamma-H2AX, BRCA1, and RAD51. We also provided evidence that irofulven induces the generation of DNA double-strand breaks. By using BRCA1-deficient or -proficient cells, we demonstrated that in response to irofulven, BRCA1 contributes to the control of S and G(2)/M cell cycle arrest and is critical for repairing DNA double-strand breaks and for RAD51-dependent homologous recombination. Furthermore, we found that BRCA1 deficiency results in increased chromosome damage and chemosensitivity after irofulven treatment.

Lung cancer is the most common cause of cancer mortality in both male and female patients in the United States of America, as well as in the rest of the world. Over one million people are diagnosed with lung cancer every year worldwide. The taxane is one of the most powerful classes of novel antitumor agents and has become an integral part of several commonly used chemotherapy regimens in lung cancer management over the past few years. Although the ability of taxanes to disrupt microtubule dynamics is well documented, the molecular basis by which taxanes suppress cancer cell growth and induce apoptotic cell death is not clearly defined. In this review, we focus on the molecular mechanisms of the antitumor activity of taxanes (paclitaxel and docetaxel) in lung cancer, and discuss the interactions of taxanes with microtubules, the roles of cell cycle control and cell death induction in the anticancer action of taxanes, as well as the signal transduction pathways involved in the processes. In addition, we discuss the possible mechanisms of taxane resistance, because drug resistance to these anti-neoplastic agents affects therapy efficacy and is also a major obstacle in the clinic for the successful treatment of lung cancer. Understanding the molecular mechanisms underlying the antitumor effect of taxanes and the drug resistance to taxanes may lead to the design of biologically and pharmacologically targeted therapeutic strategies for taxane resistant tumors, and to the improvement of chemotherapy effect and cancer patient survival.

Cisplatin is one of the most potent anticancer agents, displaying significant clinical activity against a variety of solid tumors. For more than two decades, the most effective systemic chemotherapy for non-small cell lung cancer (NSCLC), the leading cause of cancer morbidity and mortality among men and women in the western world, was cisplatin-based combination treatment. Unfortunately, the outcome of cisplatin therapy on NSCLC seems to have reached a plateau. Therefore, the biological mechanisms of cisplatin action need to be understood in order to overcome the treatment plateau on NSCLC. Moreover, the development of resistance is a hurdle in the use of this drug. The molecular mechanisms that underlie this chemoresistance are largely unknown. Possible mechanisms of acquired resistance to cisplatin include reduced intracellular accumulation of cisplatin, enhanced drug inactivation by metallothionine and glutathione, increased repair activity of DNA damage, and altered expression of oncogenes and regulatory proteins. In addition, it is generally accepted that cytotoxicity of cisplatin is mediated through induction of apoptosis and arrest of cell cycle resulting from its interaction with DNA, such as the formation of cisplatin-DNA adducts, which activates multiple signaling pathways, including those involving p53, Bcl-2 family, caspases, cyclins, CDKs, pRb, PKC, MAPK and PI3K/Akt. Increased expression of anti-apoptotic genes and mutations in the intrinsic apoptotic pathway may contribute to the inability of cells to detect DNA damage or to induce apoptosis. Towards an understanding of the molecular basis of the cellular response to cisplatin-based chemotherapy in NSCLC, in this review we provide some insights into the pathways involved in cisplatin damage from entering the cells to execution of apoptosis or survival of NSCLC cells. We believe that as more and more molecular mechanisms of response to cisplatin-based therapy are unraveled, this knowledge should provide a basis for further studies to improve our understanding of molecular events associated with lung NSCLC as well as to devise novel and effective therapeutic approaches to overcome the treatment plateau or reverse drug resistance in this disease.

SU5416 is a selective inhibitor of vascular endothelial growth factor (VEGF) receptors with anti-angiogenesis activity for human cancers. We have previously reported that SU5416 sensitizes ovarian cancer cells to cisplatin via suppression of nucleotide excision repair activity. This study sought to gain further insights into the mechanisms underlying the synergistic effect of SU5416 and cisplatin on cytotoxicity in human ovarian tumor cells. Here, we show that SU5416 inhibited the expression of G1 cell cycle checkpoint regulators, p53, p21, p27 and MDM2 in ovarian carcinoma cells. We also demonstrate that SU5416 triggered the apoptosis of these cells, in addition to augmenting the apoptosis induced by cisplatin, as determined by a Sub-G1 profile analysis using a flow cytometer. Furthermore, we show that SU5416-induced apoptosis is associated with a decrease in the expression of the apoptosis inhibitors, MDM2 and Bcl-2, and an increase in the level of NF-kappaB inhibitor, IkappaBalpha. NF-kappaB is an anti-apoptotic transcription factor, which induces the apoptosis inhibitors, Bcl-XL and IAPs (inhibitor of apoptosis proteins), and IkappaBalpha is an inhibitor of NF-kappaB, which binds to the NF-kappaB and retains it in the cytoplasm. Finally, the compound was found to block cisplatin-induced increases in AP-1 expression and JNK activity, as well as Raf-1 protein level in these cells. Together, these results suggest that the chemosensitizing effect of SU5416 on ovarian tumor cells may be mediated, at least in part, through inhibiting G1 checkpoint control and up-regulating the apoptotic response to cisplatin.

Ovarian cancer is the leading cause of death from gynecological malignancy and has the worst prognosis of all gynecological cancers. Vascular endothelial growth factor (VEGF) plays an important role in ovarian cancer development. 9-beta-D-Arabinofuranosyl-2-fluoroadenine (Fara-A), a nucleotide analog, is frequently used in treating certain types of cancer. However, the effectiveness of Fara-A on ovarian cancer cells is unknown. In this study, we found that Fara-A inhibited VEGF expression in human ovarian cancer cells. Fara-A inhibited VEGF transcriptional activation through hypoxia-inducible factor 1 (HIF-1). HIF-1 is composed of HIF-1alpha and -1beta subunits. Fara-A inhibited expression of HIF-1alpha but not HIF-1beta. Overexpression of HIF-1alpha reversed Fara-A-inhibited VEGF transcriptional activation. Our results demonstrated that Fara-A inhibited VEGF transcriptional activation through HIF-1alpha expression. Fara-A partly inhibited HIF-1alpha mRNA levels. Fara-A blocked the activation of AKT but not of ERK1/2. Overexpression of AKT reversed the Fara-A-inhibited VEGF transcriptional activation, suggesting that Fara-A inhibits VEGF expression via phosphatidylinositol 3-kinase/AKT signaling. These results demonstrate a new function of Fara-A in inhibiting VEGF and HIF-1alpha expression and identify a potential molecular mechanism of the regulation.

Purpose: Carboxyamidotriazole (CAI) is a cytostatic inhibitor of nonvoltage-operated calcium channels and calcium channel-mediated signaling pathways. It inhibits angiogenesis, tumor growth, invasion, and metastasis. We hypothesized that CAI would promote disease stabilization lasting >/= 6 months in patients with relapsed ovarian cancer., Patients and Methods: Patients with epithelial ovarian cancer, good end-organ function, measurable disease, and three or fewer prior regimens were eligible. Oral CAI was given daily using a pharmacokinetic-dosing approach to maintain plasma concentrations between 2 and 4 microg/mL. Radiographic imaging to assess response was performed every 8 weeks. Positive outcome included stabilization or improvement of disease lasting >/= 6 months. Plasma vascular endothelial growth factor (VEGF), interleukin (IL)-8, and matrix metalloproteinase (MMP)-2 were measured., Results: Thirty-six patients were assessable for primary end point analysis, and 38 were assessable for toxicity. Forty-four percent of patients had three prior regimens, more than 50% had four or more disease sites, and 48% had liver metastases. Thirty-three patients reached the targeted concentration range during the first cycle. Eleven patients (31%) attained the >/= 6-month outcome end point, with one partial response (8 months) and three minor responses (8, 12+, and 13 months). Median time to progression was 3.6 months (range, 1.6 to 13.3 months). CAI was well tolerated, with mostly grade 1 to 2 toxicity. Grade 3 events included fatigue (5%), vomiting (2%), neutropenic fever (2%), and neutropenia (2%). There were no grade 4 adverse events. No associations between VEGF, IL-8, and MMP-2 with CAI concentration or clinical outcome were observed., Conclusion: CAI is a potential agent for additional study in the stabilization of relapsed ovarian cancer. Given a limited toxicity profile, it may have utility as a maintenance therapeutic agent for this disease.

Suramin, a polysulphonated napthylurea, has been extensively evaluated over the past 10 years as an anticancer agent, with the most interest in the treatment of prostate cancer. Early clinical results were promising with response rates of up to 70% being reported. However, a recent double-blind study showed only modest palliative effect in patients with androgen independent prostate cancer. In retrospect, it appears those initial reports failed to control for confounding variables such as antiandrogen withdrawal and hydrocortisone. Suramin causes numerous reversible toxicities (lethargy, rash, fatigue, anemia, hyperglycemia, hypocalcemia, coagulopathies, neutropenia, renal and hepatic complications). Neurotoxicity has been the most significant complication and appears to be related to the intensity of the dosing regimen. An optimal therapeutic dose has not been determined, but it is clear that adaptive controls add little benefit. Aside from moderate toxicities and the low therapeutic index in patients with prostate cancer, suramin's development has taught us some valuable lessons (i.e., anti-androgen withdrawal was noted during suramin's development, the use of PSA as an indicator of tumor burden was initiated during the evaluation of suramin). These lessons can be applied to all clinical trials in hormone refractory prostate cancer. Suramin has significantly enhanced the evolution of our knowledge in several areas of prostate cancer biology and treatment.

The epothilones are a novel class of non-taxane microtubule-stabilizing agents obtained from the fermentation of the cellulose degrading myxobacteria, Sorangium cellulosum. Preclinical studies have shown that the epothilones are more potent than the taxanes and active in some taxane-resistant models. Similar to paclitaxel and other taxanes, the epothilones block cells in mitosis, resulting in cell death. The chief components of the fermentation process are epothilones A and B, with epothilones C and D found in smaller amounts. Trace amounts of other epothilones have also been detected. Pre-clinical studies have shown that epothilone B is the most active form, exhibiting significantly higher antitumor activity than paclitaxel and docetaxel. Several phase I and phase II clinical trials are ongoing with epothilone B and BMS 247550, an epothilone B analog. Preliminary reports indicate these agents are active against human cancers in heavily pre-treated patients. The epothilones appear to be well tolerated, with a side effect profile that is similar to that reported with the taxanes. This article will review some basic aspects of epothilone chemistry and biology, and pre-clinical and preliminary clinical experience with epothilone B and its analog, BMS 247550.

Objectives β-Elemene, a natural compound extracted from over 50 different Chinese medicinal herbs and plants, has been effective in the treatment of hyperplastic and proliferative disorders such as prostatic hypertrophy, hysteromyoma and neoplasms. Our previous studies have demonstrated that β-elemene exhibits strong inhibitory activity in ovarian cancer cells. The aim of the present study was to assess the effect of β-elemene on prostate cancer cells as well as other types of tumour cells and to determine whether the effect of β-elemene on prostate cancer cell death was mediated through the induction of apoptosis. Methods The MTT assay was used to evaluate the ability of β-elemene to inhibit cellular proliferation in cancer cells. Cellular apoptosis was assessed by annexin V binding, TUNEL and ELISA-based assays. Caspase activity was measured using a caspases assay kit. The protein levels of Bcl-2, caspases, cytochrome c and poly(ADP-ribose) polymerase (PARP) were analysed by Western blotting. Key findings Here, we showed that β-elemene had an antiproliferative effect on androgen-insensitive prostate carcinoma DU145 and PC-3 cells. Treatment with β-elemene also inhibited the growth of brain, breast, cervical, colon and lung carcinoma cells. The effect of β-elemene on cancer cells was dose dependent, with IC50 values ranging from 47 to 95 µg/ml (230-465 µ m). TUNEL assay and flow cytometric analysis using annxin V/propidium iodide staining revealed that the percentage of apoptotic prostate cancer cells was increased by β-elemene in a dose- and time-dependent manner. Moreover, β-elemene exposure resulted in a decreased Bcl-2 protein level, increased cytochrome c release, and activated PARP and caspase-3, -7, -9, and -10 in prostate cancer cells. Conclusions Overall, these findings suggest that β-elemene exerts broad-spectrum antitumour activity against many types of solid carcinoma and supports a proposal of β-elemene as a new potentially therapeutic drug for castration-resistant prostate cancer and other solid tumours. [ABSTRACT FROM AUTHOR]

In this phase I/II clinical trial the antitumor activity of high-dose tamoxifen when administered in combination with vinblastine was assessed and the toxicity profile of this combination characterized. All 25 patients enrolled in this study were required to have androgen-independent prostate cancer and to maintain androgen ablation during treatment. Vinblastine was given by continuous infusion over 5 days. Doses were increased from 0.9 mg/m²/day to 1.5 mg/m²/day in successive cohorts of at least 3 patients, with no further escalation even in the absence of dose-limiting toxicity. Intra-patient dose escalation was permitted. Tamoxifen was administered at a dose of 200 mg/kg on day 1, then 120 mg/kg/day on day 2. Standard response criteria were utilized to assess antitumor activity and CTC toxicity criteria were used. Quality of life (QOL) pain assessments were evaluated at each visit to the clinic. Most patients tolerated the highest dose of vinblastine at 1.5 mg/m²/day by continuous infusion over 5 days with 200 mg/kg/day of tamoxifen on day 1 and day 2. One patient had a greater than 50% decline in prostatespecific antigen that lasted for 170 days. Two patients received dose reductions because of toxicity. The most common serious toxicities included neutropenia, and fatigue. Reversible neurosensory, neuromotor, neurocortical and neurocerebellar toxicities were reported. Six of the 25 patients enrolled in the study (24%) experienced reversible neurologic toxicity of at least grade III. No statistically significant differences between precycle assessment of QOL and subsequent cycles were observed. It is concluded that vinblastine at 1.5 mg/m²/day continuous IV infusion combined with tamoxifen 200 mg/kg/day on day 1 and day 2 is inactive, and not without toxicity in the treatment of advanced metastatic androgen-independent prostate cancer. [ABSTRACT FROM AUTHOR]

Introduction: Due to in vitro data suggesting antitumor activity with gallium nitrate, we sought to evaluate the safety and activity in patients with androgen-independent prostate cancer. Method: Patients were eligible for this study if they had an ECOG performance status of ≤2, stage D2 metastatic prostate cancer that was progressing following combined androgen ablation (medical or surgical castration plus antiandrogen) and had failed antiandrogen withdrawal. Therapy consisted of gallium nitrate (200 mg/m[sup 2] /day) as a continuous infusion for 7 days, administered every 21 days, with hydration (100 ml/m[sup 2] /h). Individuals that had previously received suramin were treated at a dose of 150 mg/m[sup 2] /day of gallium nitrate. Results: Eight patients were enrolled: 4 patients at the 200 mg/m[sup 2] /day dose level and 4 patients at the lower dosage (150 mg/m[sup 2] /day). One of 8 patients had a >75% decline in prostate-specific antigen (PSA), 3 patients had stable PSA values for 17, 18 and 22 weeks, and 4 patients had progression by PSA (>50% increase over baseline). Anemia requiring transfusion occurred in 5 of 8 patients (63%). Two patients (25%) developed grade 4 toxicity: 1 patient developed complete blindness with partial reversal over 12 months, and another patient had pulmonary infiltrates, hypoxemia, and fever. Serious adverse events were not correlated to prior suramin exposure, or gallium plasma concentrations (total or free), but appeared to be related to cumulative cycles of gallium nitrate. Remaining adverse events were grade 1 or 2. No patients developed renal or neurological toxicity. Conclusion: This trial was prematurely terminated because repeated administration of gallium nitrate was poorly tolerated in an elderly population with androgen-independent prostate cancer. Gallium had modest clinical activity in this disease.Copyright © 1999 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: Checkpoint kinase 2 (Chk2) is one of the critical kinases governing the cell cycle checkpoint, DNA damage repair, and cell apoptosis in response to DNA damaging signals. In the present report, we demonstrate that Chk2 kinase is degraded at the protein level in response to cisplatin through ubiquitin–proteasome pathway. This degradation was independent of the Thr68 phosphorylation, ATM kinase, and BRCA1 tumor suppressor. Examination of Chk2 protein revealed a decreased expression of Chk2 protein in cisplatin-resistant ovarian cancer cell lines, suggesting that degradation or decreased expression of Chk2 is partially responsible for chemo-resistance. Site-directed mutation of the putative destruction box in the Chk2 protein did not affect the Chk2 degradation induced by cisplatin. Therefore, these results are the first to indicate a novel mechanism of regulating Chk2 in cisplatin-induced resistance of cancer cells. [Copyright &y& Elsevier]

Irofulven (6-hydroxymethylacylfulvene, HMAF, MGI 114) is one of a new class of anticancer agents that are semisynthetic derivatives of the mushroom toxin illudin S. Preclinical studies and clinical trials have demonstrated that irofulven is effective against several tumor types. Mechanisms of action studies indicate that irofulven induces DNA damage, MAPK activation, and apoptosis. In this study we found that in ovarian cancer cells, CHK2 kinase is activated by irofulven while CHK1 kinase is not activated even when treated at higher concentrations of the drug. By using GM00847 human fibroblast expressing tetracycline-controlled, FLAG-tagged kinase-dead ATR (ATR.kd), it was demonstrated that ATR kinase does not play a major role in irofulven-induced CHK2 activation. Results from human fibroblasts proficient or deficient in ATM function (GM00637 and GM05849) indicated that CHK2 activation by irofulven is mediated by the upstream ATM kinase. Phosphorylation of ATM on Ser1981, which is critical for kinase activation, was observed in ovarian cancer cell lines treated with irofulven. RNA interference results confirmed that CHK2 activation was inhibited after introducing siRNA for ATM. Finally, experiments done with human colon cancer cell line HCT116 and its isogenic CHK2 knockout derivative; and experiments done by expressing kinase-dead CHK2 in an ovarian cancer cell line demonstrated that CHK2 activation contributes to irofulven-induced S phase arrest. In addition, it was shown that NBS1, SMC1, and p53 were phosphorylated in an ATM-dependent manner, and p53 phosphorylation on serine 20 is dependent on CHK2 after irofulven treatment. In summary, we found that the anticancer agent, irofulven, activates the ATM-CHK2 DNA damage-signaling pathway, and CHK2 activation contributes to S phase cell cycle arrest induced by irofulven. [ABSTRACT FROM AUTHOR]