Abrogation of cisplatin-induced programmed cell death in human breast cancer cells by epidermal growth factor antisense RNA

Does resveratrol reduce cisplatin-induced ovarian damage?

OBJECTIVE

The objective of this study was to investigate the protectiveness of resveratrol on cisplatin-induced damage to the ovary using experimental models.

METHODS

A total of 30 female Wistar-Albino rats constituted the research material. The rats were categorized into three groups: Group 1 was administered one milliliter of 0.9% NaCl solution, Group 2 was administered 7.5 mg/kg cisplatin, and Group 3 was administered 7.5 mg/kg cisplatin and 10 mg/kg resveratrol. Ovaries were extirpated in all groups and subjected to biochemical and histopathological tests. Cisplatin-induced damage to ovarian tissue was graded and scored as the total histopathological findings score. The ovarian function was assessed using immunohistochemical staining for c-kit expression. Rats' malondialdehyde, catalase, and superoxide dismutase levels were determined.

RESULTS

The histopathological finding score was significantly higher in Group 2 than in other groups (p<0.05). The superoxide dismutase and catalase levels were significantly higher in Group 3 than in Group 2 (p<0.001 for both cases). The malondialdehyde level was significantly higher in Group 2 than in Group 3 (p<0.001).

CONCLUSION

The study findings demonstrated that resveratrol reduced ovarian injury and enhanced biochemical parameters following cisplatin-induced ovary damage in experimental models.

Protective effect of edaravone on cisplatin-induced injury in rat ovary

PURPOSE

This study was aimed to evaluate the protective effect of edaravone on cisplatin-induced ovarian injury.

METHODS

A total 40 female Wistar-Albino rats were utilized to form four groups: Group 1 (control group) (n = 10), no procedure was performed. Group 2 (cisplatin group) (n = 10), single-dose 7.5 mg/kg cisplatin was administered and no procedure was performed. Group 3 (edaravone group) (n = 10), single-dose 1 mg/kg edaravone was administered and no procedure was performed. Group 4 (cisplatin + edaravone group) (n = 10), single-dose 7.5 mg/kg cisplatin and 1 mg/kg edaravone were administered. Seventy-two hours later, ovaries were surgically extirpated in all groups. Malondialdehyde (MDA) levels and nitric oxide (NO) levels were studied in blood samples. In ovarian tissue samples, DNA damage and apoptosis were assessed using TUNEL method. Ovarian tissue damage was evaluated by immunohistochemical staining with caspase 3 and caspase 8.

RESULTS

According to the findings obtained from the study, edaravone showed protective properties on ovarian damage due to cisplatin. MDA and NO levels were significantly higher in cisplatin group than other groups. Histopathological ovarian tissue damage in the cisplatin group was significantly higher than other groups. Similarly, DNA damage and apoptosis were higher in cisplatin group and this difference was found to be statistically significant. The immunohistochemical staining which was done using caspase 3 and caspase 8 was revealed that immunoreactive cells were statistically higher in cisplatin group than cisplatin + edaravone group.

CONCLUSION

Edaravone seems to be effective in prevention of ovarian damage and short-term treatment.

Rosmarinic acid relieves cisplatin-induced ovary toxicity in female mice via suppression of oxidative stress and inflammation

Rosmarinic acid having potential anti-inflammatory and free radical scavenging activity. We examined the chemotherapeutic effect of rosmarinic against cisplatin (CIS)-induced ovarian toxicity via modulation of oxidative stress and inflammation. Swiss BALB mice used in experimental protocol and mice were divided into different groups. Intraperitoneal injection of CIS (7 mg/kg) was used for ovarian cancer induction. The rats were received rosmarinic acid (2.5, 5, and 10 mg/kg, body weight) treatment for 22 weeks. Body weight, ovary weight food, and water intake were estimated at regular time intervals. Hormonal and antioxidant parameters were estimated in the ovary tissue and serum at the end of the study. Cytokines, inflammatory, and apoptosis parameters were determined at the end of the study. Finally, the ovary tissue histopathology was performed at end of the experimental study. Rosmarinic acid significantly (p < 0.001) improved the body weight and reduced the ovary weight. Rosmarinic acid considerably reduced the hormonal assay parameters, such as antimullerian hormone, estradiol, luteinizing hormone, and follicle-stimulating hormone compared to model control mice. Rosmarinic treatment significantly (p < 0.001) reduced the level of nitric oxide, myeloperoxidase, and boosted the level of antioxidant parameters, such as glutathione, superoxide dismutase, catalase, and glutathione peroxidase in serum and ovary tissue. Rosmarinic acid downregulated the cytokines like interleukin-6, tumor necrosis factor-α, interleukin-1β; inflammatory parameter includes prostaglandin E2 , cyclooxygenase-2, and inducible nitric oxide synthase at a dose-dependently. Ovary tissue histopathology showed improvement after rosmarinic acid treatment. The result suggests that rosmarinic acid is a protective effect in ameliorating CIS-induced ovary toxicity via alteration of inflammatory and apoptosis parameters.

Efficacy of Paclitaxel plus TS1 against previously treated EGFR mutated non-small cell lung cancer

Background

Later line chemotherapy (≥2nd lines) such as Docetaxel or immunotherapy is frequently used. As the life expectancy of lung cancer patients is getting longer, we need to provide more treatment options. Other treatment options are not well documented except for Doxetaxel and immunotherapy. Therefore, the efficacy of paclitaxel plus TS1 (TTS1) is warranted.

Methods

We retrospectively reviewed the chart records of our non-small cell lung cancer patients who were treated between 2010 and 2013. Clinical characteristics, type of tumor, EGFR mutation status, and treatment response to first-line EGFR-TKI therapy and efficacy of TTS1, were collected.

Results

Twenty eight patients were enrolled in this study. No patients archived complete response and seven patients had partial response (ORR: 25%). The disease control rate was 60.7% (17/28). The progression free survival (PFS) was 4.0 months and overall survival (OS) was 15.8 months. Of them, 17 had EGFR mutations, eight EGFR wild type, and three were unknown EGFR status. After TTS1 treatment, patients with EGFR mutations had better PFS (4.9 months vs. 1.8 months) and OS (15.5 months vs. 7.2 months) compared with those of EGFR wild type.

Conclusions

TTS1 are effective later line chemotherapy, especially in tumor EGFR mutated patients. Paclitaxel plus TS1 is another treatment of choice for NSCLC patients before a more effective treatment strategy is found.

Constitutively activated ERK sensitizes cancer cells to doxorubicin: Involvement of p53-EGFR-ERK pathway

The tumour suppressor gene p53 is mutated in approximately 50% of the human cancers. p53 is involved in genotoxic stress-induced cellular responses. The role of EGFR and ERK in DNA-damage-induced apoptosis is well known. We investigated the involvement of activation of ERK signalling as a consequence of non-functional p53, in sensitivity of cells to doxorubicin. We performed cell survival assays in cancer cell lines with varying p53 status: MCF-7 (wild-type p53, WTp53), MDA MB-468 (mutant p53, MUTp53), H1299 (absence of p53, NULLp53) and an isogenic cell line MCF-7As (WTp53 abrogated). Our results indicate that enhanced chemosensitivity of cells lacking wild-type p53 function is because of elevated levels of EGFR which activates ERK. Additionally, we noted that independent of p53 status, pERK contributes to doxorubicin-induced cell death.

Lidocaine sensitizes the cytotoxicity of cisplatin in breast cancer cells via up-regulation of RARβ2 and RASSF1A demethylation

It has been reported that lidocaine is toxic to various types of cells. And a recent study has confirmed that lidocaine exerts a demethylation effect and regulates the proliferation of human breast cancer cell lines. To recognize a potential anti-tumor effect of lidocaine, we evaluated the DNA demethylation by lidocaine in human breast cancer lines, MCF-7 and MDA-MB-231 cells, and determined the influence of demethylation on the toxicity to these cells of cisplatin, which is a commonly utilized anti-tumor agent for breast cancer. Results demonstrated that lidocaine promoted a significant global genomic demethylation, and particularly in the promoters of tumor suppressive genes (TSGs), RARβ2 and RASSF1A. Further, the lidocaine treatment increased cisplatin-induced apoptosis and enhanced cisplatin-induced cytotoxicity. The combined treatment with both lidocaine and cisplatin promoted a significantly higher level of MCF-7 cell apoptosis than singular lidocaine or cisplatin treatment. Moreover, the abrogation of RARβ2 or RASSF1A expression inhibited such apoptosis. In conclusion, the present study confirms the demethylation effect of lidocaine in breast cancer cells, and found that the demethylation of RARβ2 and RASSF1A sensitized the cytotoxicity of cisplatin in breast cancer cells.

Impact of EGFR mutation status on tumor response and progression free survival after first-line chemotherapy in patients with advanced non-small-cell lung cancer: a meta-analysis

OBJECTIVES

Non-small-cell lung cancer (NSCLC) patients harboring sensitive epidermal growth factor receptor (EGFR) mutations derive greater benefits from EGFR-tyrosine kinase inhibitors (EGFR-TKIs) than those with wild type tumors. However, whether EGFR mutation status is associated with the efficacy of cytotoxic chemotherapy or prognosis in advanced NSCLC patients remained controversial. Thus, we sought to conduct a meta-analysis to answer this question.

METHODS

Electronic databases were searched for eligible literatures. The primary outcomes were objective response rate (ORR) and 6-month progression-free survival (PFS) rate. The pooled odds ratio (OR) was calculated using random-effects model. Subgroup analyses stratified by study types, EGFR mutation detection methods, chemotherapy regimens, and patient origins were proposed.

RESULTS

A total of 14 studies involving 1,772 advanced NSCLC patients with known EGFR mutation status who had received first-line chemotherapy were included. Patients with positive EGFR mutation had numerically higher ORR than wild type patients (36.2% vs. 30.1%) without significant differences (OR 1.24, 95% CI, 0.90 to 1.70; P=0.19). However, patients with EGFR mutants had significantly superior 6-month PFS rate than wild-type patients (58.6% vs. 47.2%; OR 1.88, 95% CI, 1.33 to 2.65; P=0.0003). Results of the subgroup analyses were concordant with the overall ones.

CONCLUSIONS

This comprehensive analysis revealed that advanced NSCLC patients with sensitivity EGFR mutation had higher 6-month PFS rate and potentially greater ORR compared with wild-type patients after first-line chemotherapy. It suggested that EGFR mutation status should be considered a significant factor for patient stratification in evaluating the efficacy of antitumor agents in addition to EGFR-TKIs.

Protective effect of bilberry (Vaccinium myrtillus L.) on cisplatin induced ovarian damage in rat

Cisplatin is one of the most effective chemotherapeutic agents but injury may occur at higher doses. The aim of this study was to investigate the effect of bilberry on cisplatin induced toxic effects in rat ovary. Twenty-one female Wistar-Albino rats were utilized to form three groups: In group 1 (control group), each rat received intraperitoneal injection of 1 mL of 0.9 % NaCl saline solution during 10-days. In group 2 (cisplatin group), a single dose of 7.5 mg/kg b.w. cisplatin was given. In group 3 (cisplatin + bilberry group), a single dose of 7.5 mg/kg cisplatin and bilberry at 200 mg/kg b.w. were given for 10 days. Ovaries were surgically removed in all groups and prepared for biochemical and light microscopic investigations at the examination times. Malondialdehyde (MDA) levels and activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) of tissue samples were measured. Histopathological damages in cisplatin administrated rats were seen such as severe edema, vascular congestion, hemorrhage and follicular degeneration in the ovary tissue. Moderate pathological alterations were observed in rats treated with bilberry plus cisplatin. Cisplatin administration significantly increased MDA production and decreased SOD, CAT, GPx and GST activities in the ovarian tissue when compared to the control group (p < 0.05). Cisplatin + bilberry administration increased antioxidant enzymes activities and reduced MDA levels. Bilberry administration seems to reduce the cisplatin induced ovarian toxicity thus it alleviates free radical damage. But it dose not protect completely rat ovary tissues.

Heterogeneity of functional properties of Clone 66 murine breast cancer cells expressing various stem cell phenotypes

INTRODUCTION

Breast cancer grows, metastasizes and relapses from rare, therapy resistant cells with a stem cell phenotype (cancer stem cells/CSCs). However, there is a lack of studies comparing the functions of CSCs isolated using different phenotypes in order to determine if CSCs are homogeneous or heterogeneous.

METHODS

Cells with various stem cell phenotypes were isolated by sorting from Clone 66 murine breast cancer cells that grow orthotopically in immune intact syngeneic mice. These populations were compared by in vitro functional assays for proliferation, growth, sphere and colony formation; and in vivo limiting dilution analysis of tumorigenesis.

RESULTS

The proportion of cells expressing CD44(high)CD24(low/neg), side population (SP) cells, ALDH1(+), CD49f(high), CD133(high), and CD34(high) differed, suggesting heterogeneity. Differences in frequency and size of tumor spheres from these populations were observed. Higher rates of proliferation of non-SP, ALDH1(+), CD34(low), and CD49f(high) suggested properties of transit amplifying cells. Colony formation was higher from ALDH1(-) and non-SP cells than ALDH1(+) and SP cells suggesting a progenitor phenotype. The frequency of clonal colonies that grew in agar varied and was differentially altered by the presence of Matrigel™. In vivo, fewer cells with a stem cell phenotype were needed for tumor formation than "non-stem" cells. Fewer SP cells were needed to form tumors than ALDH1(+) cells suggesting further heterogeneities of cells with stem phenotypes. Different levels of cytokines/chemokines were produced by Clone 66 with RANTES being the highest. Whether the heterogeneity reflects soluble factor production remains to be determined.

CONCLUSIONS

These data demonstrate that Clone 66 murine breast cancer cells that express stem cell phenotypes are heterogeneous and exhibit different functional properties, and this may also be the case for human breast cancer stem cells.

MUC4 overexpression augments cell migration and metastasis through EGFR family proteins in triple negative breast cancer cells

INTRODUCTION

Current studies indicate that triple negative breast cancer (TNBC), an aggressive breast cancer subtype, is associated with poor prognosis and an early pattern of metastasis. Emerging evidence suggests that MUC4 mucin is associated with metastasis of various cancers, including breast cancer. However, the functional role of MUC4 remains unclear in breast cancers, especially in TNBCs.

METHOD

In the present study, we investigated the functional and mechanistic roles of MUC4 in potentiating pathogenic signals including EGFR family proteins to promote TNBC aggressiveness using in vitro and in vivo studies. Further, we studied the expression of MUC4 in invasive TNBC tissue and normal breast tissue by immunostaining.

RESULTS

MUC4 promotes proliferation, anchorage-dependent and-independent growth of TNBC cells, augments TNBC cell migratory and invasive potential in vitro, and enhances tumorigenicity and metastasis in vivo. In addition, our studies demonstrated that MUC4 up-regulates the EGFR family of proteins, and augments downstream Erk1/2, PKC-γ, and FAK mediated oncogenic signaling. Moreover, our studies also showed that knockdown of MUC4 in TNBC cells induced molecular changes suggestive of mesenchymal to epithelial transition. We also demonstrated in this study, for the first time, that knockdown of MUC4 was associated with reduced expression of EGFR and ErbB3 (EGFR family proteins) in TNBC cells, suggesting that MUC4 uses an alternative to ErbB2 mechanism to promote aggressiveness. We further demonstrate that MUC4 is differentially over-expressed in invasive TNBC tissues compared to normal breast tissue.

CONCLUSIONS

MUC4 mucin expression is associated with TNBC pathobiology, and its knockdown reduced aggressiveness in vitro, and tumorigenesis and metastasis in vivo. Overall, our findings suggest that MUC4 mucin promotes invasive activities of TNBC cells by altering the expression of EGFR, ErbB2, and ErbB3 molecules and their downstream signaling.

The role of oncogenes in drug resistance

Increasing evidences indicate that oncogenes can directly or indirectly impact on cancer-cell drug resistance. This chapter provides a conceptual review regarding the role of oncogenes in drug resistance. The review is focused on drug resistance mediated by oncogenes encoding growth factor receptors, signaling molecules, transcription factors, cell-cycle regulators, and apoptosis regulators. It is my hope that better undertsnading on the role of oncogenes in drug resistance will invoke ideas on new approaches to enhance the cytotoxicity of the standard chemotherapeutic agents by functional perturbation of resistance-inducing oncogenes.

Cisplatin induces platelet apoptosis through the ERK signaling pathway

Cisplatin (cis-diamminedichloroplatinum II) is one of the most widely used anti-tumor agents. However, cisplatin-based chemotherapy is usually accompanied by adverse side effects such as thrombocytopenia, and the mechanism remains unclear. Here we show that cisplatin induced several platelet apoptotic events including up-regulation of Bax and Bak, down-regulation of Bcl-2 and Bcl-X(L), mitochondrial translocation of Bax, mitochondrial inner transmembrane potential depolarization, caspase-3 activation and phosphatidylserine (PS) exposure. Cisplatin dose-dependently induced activation of extracellular signal-regulated protein kinase (ERK) in platelets. Caspase-3 inhibitor z-DEVD-fmk dramatically inhibited cisplatin-induced caspase-3 activation and PS exposure without affecting ERK activation. Blockade of the ERK pathway significantly prevented platelet apoptosis. Furthermore, levels of reactive oxygen species (ROS) and Ca(2+) were significantly elevated by cisplatin, and scavenging of ROS and Ca(2+) obviously inhibited platelet apoptosis induced by cisplatin. In addition, cisplatin did not induce platelet activation, whereas it obviously impaired platelet functions. These data indicate that cisplatin induces platelet apoptosis through the ERK signaling pathway, which might contribute to cisplatin-related haematological toxicity.

Association of epidermal growth factor receptor activating mutations with low ERCC1 gene expression in non-small cell lung cancer

INTRODUCTION

Patients with non-small cell lung cancer (NSCLC) with cancers harboring activating mutations in the epidermal growth factor receptor (EGFR) show improved efficacy from EGFR tyrosine kinase inhibitors. Some clinical studies also suggest enhanced efficacy of platinum-based chemotherapy in patients with EGFR-mutant cancers. We investigated the relationship of EGFR mutation status and DNA repair capacity, as exemplified by excision repair cross-complementing 1 (ERCC1) gene expression, as a potential explanation for this observation.

METHODS

Microdissected formalin-fixed paraffin-embedded tumors from 1207 patients with NSCLC were analyzed by real-time polymerase chain reaction for mRNA expression levels of ERCC1 and for EGFR mutation status by an allele-specific polymerase chain reaction assay.

RESULTS

NSCLC subtype was adenocarcinoma (AC) in 712 patients, squamous in 175, and not otherwise specified or other in 320. EGFR activating mutations were detected in 183/1207 patients (15.2%). Median ERCC1 expression overall was 1.82 (range, 0.22-27.31) and was histology related: AC, median = 1.68 (0.22-11.33) and squamous, median = 2.42 (0.51-14.28) (p < 0.001). Using a previously defined reference level of <1.7, ERCC1 expression was categorized as low in 556 of 1207 patients (46.1%). The presence of EGFR mutations was highly associated with ERCC1 expression (p < 0.001). This association was retained when adjusting for AC histologic subtype (p = 0.001).

CONCLUSIONS

NSCLC specimens harboring EGFR activating mutations are more likely to express low ERCC1 mRNA levels. Whether these findings translate into enhanced clinical efficacy of EGFR-mutant cancers to platinum-based chemotherapy remains to be determined.

Clinical outcome of patients with non-small cell lung cancer receiving front-line chemotherapy according to EGFR and K-RAS mutation status

BACKGROUND

Somatic mutations in EGFR and K-RAS may predict for sensitivity and resistance to EGFR tyrosine kinase inhibitors (TKIs). Whether EGFR and K-RAS mutations could also predict clinical outcome of non-small cell lung cancer (NSCLC) patients following front-line chemotherapy has not yet been established.

PATIENTS AND METHODS

One hundred and sixty-two chemotherapy-naïve patients with locally advanced/metastatic NSCLC who received front-line chemotherapy were included in this retrospective study and their clinical outcome data was analyzed according to EGFR and K-RAS mutation status of their tumors.

RESULTS

Classical activating EGFR and K-RAS mutations were found in 8.2 and 22.6% of patients respectively and were not associated with patients' clinicopathological characteristics. Patients with classical EGFR mutations had a higher probability of response to front-line chemotherapy as compared to those with wild type EGFR (p=0.023). Multivariate analysis showed that the presence of activating EGFR mutations was an independent factor associated with response to front-line chemotherapy (HR=4.85; 95% CI: 1.13-20.83, p=0.034). K-RAS mutation status was not associated with response to front-line chemotherapy. The presence of activating EGFR but not of K-RAS mutations was associated with a significantly higher overall survival compared to patients without mutations treated with platinum-based front-line chemotherapy (p=0.043).

CONCLUSIONS

The data indicate that EGFR mutation status could be predictive for response to cytotoxic front-line chemotherapy in patients with NSCLC. Additional prospective studies are needed in order to validate this observation and to define whether these patients should be preferentially treated with front-line TKIs or chemotherapy.

Interactions of doxycycline with chemotherapeutic agents in human breast adenocarcinoma MDA-MB-231 cells

Commonly used chemotherapeutic agents for breast cancer treatment include cisplatin, doxorubicin, and paclitaxel. Unfortunately, these effective antiproliferative agents are limited by their toxicities. Previously, we have shown that doxycycline can substantially reduce tumor burden in an animal model of breast cancer bone metastasis. The purpose of this study was to examine the effect of doxycycline in combination with chemotherapy. Human breast adenocarcinoma MDA-MB-231 cells were treated in vitro with each drug individually and in combination with doxycycline. Cell survival was determined using the clonogenic survival assay. Doxycycline in combination with doxorubicin or paclitaxel yielded therapeutic antagonism at all effect levels. Combinatory treatment with cisplatin, however, yielded a biphasic interaction, at low combinatorial doses, the effect was quantified as nearly additive, whereas higher doxycycline-cisplatin doses yielding greater than 50% cell inhibition resulted in synergistic effects. Cell cycle profiles were determined and showed that treatment with doxycycline, cisplatin, and doxorubicin resulted in G1-phase, S-phase, and G2/M-phase arrests, respectively. Upon addition of doxycycline to doxorubicin, the G2/M-arrest characteristic of doxorubicin-only treatment was abrogated, which may account for the observed antagonism. Cells treated with doxycycline and cisplatin showed a further increase in S-phase arrest, also observed with cisplatin alone, which may be responsible for the additive and synergistic effects on cell survival. We clearly show that doxycycline in combination with paclitaxel or doxorubicin treatment resulted in antagonism; however, combining doxycycline with cisplatin led to synergistic interactions at higher effect levels. The increased potency of cisplatin may warrant dose reduction and thus decrease toxicity in vivo.

Dose-dependent and sequence-dependent cytotoxicity of erlotinib and docetaxel in head and neck squamous cell carcinoma

The purpose of this study was to determine whether the efficacy of taxoid treatment combined with epidermal growth factor receptor (EGFR) inhibition is dose and sequence dependent in head and neck squamous cell carcinoma. Three head and neck squamous cell carcinoma cell lines, chosen on the basis of their diverse EGFR expression levels, were treated with docetaxel, erlotinib, or both. The combination index was calculated using the Chou-Talalay equation. Propidium iodide staining with fluorescence-activated cell sorting analysis was used to evaluate the effects of drugs on cell cycle changes. Western blot analysis was used to determine the effects of agents on cell signaling pathways. Administration of low-dose docetaxel (0.1-3 nmol/l) concurrently or before erlotinib had additive cytotoxic effects in two cell lines but was antagonistic in one line, whereas low-dose docetaxel after erlotinib was synergistic in all cell lines. In contrast, high-dose docetaxel (40 nmol/l) resulted in more apoptosis when given before, rather than after or concurrently with, erlotinib. Low-dose docetaxel induced an accumulation of cells in the sub-G0 phase of the cell cycle with no mitotic arrest or apoptosis, whereas high-dose docetaxel induced mitotic arrest and apoptosis. The low and high doses of docetaxel had opposite effects on EGFR expression: a decrease and an increase, respectively. The dose of docetaxel affects sequence-dependent cytotoxicity when docetaxel is combined with an EGFR inhibitor. The mechanism for this difference is a combination of the dose-dependent effects of docetaxel on the mode of cell death and on EGFR expression.

Protection against cisplatin-induced ovarian damage by the antioxidant sodium 2-mercaptoethanesulfonate (mesna) in female rats

OBJECTIVE

The hypothesis was that the administration of the antioxidant mesna (sodium 2-mercaptoethanesulfonate) during chemotherapy would protect ovaries against follicular damage.

STUDY DESIGN

Sprague-Dawley rats were treated with saline solution, mesna-plus-cisplatin, or cisplatin. Immunohistochemistry was used to evaluate the Müllerian inhibiting substance (MIS) positive follicles. Serum and ovarian MIS were measured with enzyme-linked immunosorbent assay and Western blot analysis, respectively. Apoptosis in ovaries was studied by terminal deoxynucleotidyl transfer biotin-d UTP nick end labeling (TUNEL) assay.

RESULT

Immunofluorescence staining for MIS was higher in preantral follicles in the mesna-plus-cisplatin group. The ovarian and serum MIS levels were higher in the mesna-plus-cisplatin than in the cisplatin alone group. There were no differences statistically in the TUNEL and the ovarian cyst analyses.

CONCLUSION

Mesna, which was used at the time of cisplatin administration, protected ovaries against damage. The data that are presented challenge the existing clinical paradigm that gonadotropin-releasing hormone agonists represent the only medical method for the protection of ovaries during chemotherapy. Alternative medical means to protect ovaries during chemotherapy may be achievable.

Clinical significance of epidermal growth factor receptor gene mutations on treatment outcome after first-line cytotoxic chemotherapy in Japanese patients with non-small cell lung cancer

INTRODUCTION

The relationship between the EGFR gene mutation status and clinical outcome has not fully been assessed in patients with non-small cell lung cancer (NSCLC) who received cytotoxic agents. The aim of this study was to clarify its association. We also examined whether this association could be affected by previous gefitinib treatment.

METHODS

Patients with advanced or postoperative recurrent NSCLC who received both cytotoxic chemotherapy and gefitinib monotherapy in their treatment course were included in this study. An EGFR mutation was determined in exons 19 and 21 by direct sequencing.

RESULTS

Of 194 Japanese patients with advanced or relapsed NSCLC assessable for mutation analysis, 60 received both cytotoxic chemotherapy and gefitinib monotherapy through their treatment courses. EGFR mutations significantly affected progression-free survival (PFS) in the first-line cytotoxic chemotherapy regimens in the multivariate analysis (hazard ratio for PFS = 0.422; p = 0.0422). In contrast, in 28 (47%) of the 60 patients who also received cytotoxic chemotherapy after the relapse to gefitinib monotherapy, there were no differences in PFS stratified by EGFR mutation status. The sensitivity to gefitinib was, however, correlated with EGFR mutation status, and its sensitivity was retained even in the second-line treatment setting in patients with EGFR mutations.

CONCLUSIONS

EGFR mutations were therefore significantly associated with a better PFS in the first-line cytotoxic chemotherapy regimens. However, its association was not observed in the cytotoxic regimens administered after the relapse to gefitinib monotherapy, whereas gefitinib sensitivity was associated with an EGFR mutation even in the second-line or later treatment settings.

EGFR and HER2 gene copy number and response to first-line chemotherapy in patients with advanced non-small cell lung cancer (NSCLC)

BACKGROUND

A critical point in designing clinical trials comparing chemotherapy with epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in patients with non-small cell lung cancer (NSCLC) is the expected benefit with standard chemotherapy in presence of biological features indicative of TKI sensitivity. The aim of this study was to assess whether EGFR and HER2 gene copy number and Akt activation are associated with response to first-line chemotherapy.

METHODS

Tumor samples from 190 patients with NSCLC were analyzed. EGFR and HER2 gene copy number were evaluated by fluorescence in situ hybridization in 185 and 184 cases, respectively. Akt activation was assessed by immunohistochemistry (n = 176). Additional biomarkers included EGFR DNA sequencing (n = 65), and EGFR immunohistochemistry (n = 185).

RESULTS

Response rate was not associated with EGFR, HER2, and P-Akt status, irrespective of the method used for biomarker assessment. Among patients with EGFR gene mutations, response to chemotherapy was observed only in individuals with exon 19 deletion (response rate: 46.6% versus 0%, p = 0.02). Among the 190 patients analyzed, 123 received a treatment with a TKI as second- or third-line therapy. When assessed by fluorescence in situ hybridization or DNA sequencing, EGFR-positive patients seemed to be more sensitive to TKIs than to chemotherapy in terms of response rate and time to progression, whereas in EGFR-negative patients, response rate and time to progression favored chemotherapy.

CONCLUSION

This study suggested that EGFR expression and gene copy number, HER2 gene copy number, and P-Akt expression are not associated with response to first-line chemotherapy in NSCLC. Prospective phase III trials should compare standard chemotherapy with a TKI in selected NSCLC.

Cisplatin cytotoxicity in organ of corti-derived immortalized cells

Cisplatin is an anticancer drug currently used in the treatment of genital and head and neck tumors. Its use in these and other types of tumors is narrowed by onset of chemoresistance and severe undesired side effects, like as nephro- and ototoxicity, whose mechanisms of action are only partially understood. In the present study we investigated the effects of cisplatin (cis-dichlorodiaminoplatin, CDDP) on a cell line (OC-k3) developed from organs of Corti of transgenic mice. We observed at 48 h that cell death due to cisplatin was time and concentration-dependent. The cell death displayed some morphological hallmarks of apoptosis, including nuclear fragmentation into several large nuclear fragments, surrounded by a rearranged and thickened actin cytoskeleton. No DNA laddering was detected, suggesting absence of endonuclease activity, nor annexin V positivity, suggesting absence of phosphatidylserine externalization. Several molecules protected the cells against CDDP induced cytotoxicity, including methionine, suramin and PD98059. Methionine reduced CDDP-uptake, while suramin, a polycathionic compound a specifically binding external proteins, did not. This finding suggested that suramin could exert its protective effect by acting on an intracellular transduction pathway. We tested this hypothesis by studying the effect of suramin and PD98059, a MEK inhibitor, on the mitogen activated protein kinase (MAPK) cascade. After CDDP treatment, we found an increase of phosphorylation of extracellular regulated kinases (ERK)1/2, that could be inhibited by PD98059 and suramin. These data suggest that ERK pathways can play a role in mediating the cell death induction in presence of a CDDP challenge.

Sensitization of malignant glioma to chemotherapy through dendritic cell vaccination

Drug resistance represents a major cause of chemotherapy failure in patients with cancer. The characterization of the molecular pathways involved in drug resistance has provided new targets to circumvent or reverse chemotherapy resistance. Many of these target proteins are often overexpressed in human glioma and have been identified as tumor antigens, which implicate the development of immunotherapy as a therapeutic strategy. Dendritic cells (DCs) are the most potent antigen-presenting cells of the immune system and have been demonstrated to stimulate antibody and cell-mediated immune responses against tumor-associated antigens. Ex vivo-generated and tumor antigen-loaded DCs have been successfully introduced to clinical vaccination protocols, which have proven to be feasible and effective in some glioma patients. Most importantly, immunotherapy followed by chemotherapy could significantly increase 2-year survival in malignant glioma patients, which obviously demonstrates that DC vaccination could increase the sensitivity of tumor cells to chemotherapy. This review focuses on recent advances in the identification of tumor-associated antigen in glioma, as well as novel insights into their biological function related to drug resistance. These insights may provide the rationale for a novel strategy of a DC cancer vaccine that sensitizes tumor cells to chemotherapy. In addition, the current research status and the future direction of a DC-based vaccine to treat glioma in animal models and clinical trials will also be discussed.

CD95-mediated apoptosis of human glioma cells: modulation by epidermal growth factor receptor activity

The death ligands CD95L and Apo2L/TRAIL are promising investigational agents for the treatment of malignant glioma. EGFR is overexpressed in a significant proportion of malignant gliomas in vivo. Here, we report that CD95L-induced cell death is enhanced by EGFR inhibition using tyrphostine AG1478 in 7 of 12 human malignant glioma cell lines. Conversely, CD95-mediated and Apo2L-induced cell death are both inhibited by overexpression of EGFR in LN-229 cells. CD95L-induced cell death augmented by AG1478 is accompanied by enhanced processing of caspase 8. LN-229 cells overexpressing the viral caspase inhibitor, crm-A, are not sensitized to CD95L-induced cell death by AG1478, indicating that EGFR exerts its antiapoptotic properties through a caspase 8-dependent pathway. These data define a modulatory effect of EGFR-activity on death ligand-induced apoptosis and indicate that EGFR inhibition is likely to improve the efficacy of death ligand-based cancer therapies. Furthermore, it is tempting to speculate that EGFR amplification protects tumor cells from death ligand-mediated host immune responses in vivo and that EGFR's effects on death receptor-mediated apoptosis may explain the anti-tumor effects of non-cytotoxic, unarmed anti-EGFR family antibodies.

Lack of EGF receptor contributes to drug sensitivity of human germline cells

Germline mutations have been associated with generation of various types of tumour. In this study, we investigated genetic alteration of germline tumours that affect the drug sensitivity of cells. Although all germline tumour cells we tested were hypersensitive to DNA-damaging drugs, no significant alteration was observed in their DNA repair activity or the expression of DNA repair proteins. In contrast, germline tumours expressed very low level of epidermal growth factor receptor (EGFR) compared to drug-resistant ovarian cancer cells. An immunohistochemical analysis indicated that most of the primary germline tumours we tested expressed very low level of EGFR. In accordance with this, overexpression of EGFR in germline tumour cells showed an increase in drug resistance, suggesting that a lack of EGFR, at least in part, contributes to the drug sensitivity of germline tumours.

Targeting multiple signaling pathways as a strategy for managing prostate cancer: multifocal signal modulation therapy

The aberrant behavior of cancer reflects upregulation of certain oncogenic signaling pathways that promote proliferation, inhibit apoptosis, and enable the cancer to spread and evoke angiogenesis. Theoretically, it should be feasible to decrease the activity of these pathways-or increase the activity of pathways that oppose them-with noncytotoxic agents. Since multiple pathways are dysfunctional in most cancers, and cancers accumulate new oncogenic mutations as they progress, the greatest and most durable therapeutic benefit will likely be achieved with combination regimens that address several targets. Thus, a multifocal signal modulation therapy (MSMT) of cancer is proposed. This concept has already been documented by researchers who have shown that certain combinations of signal modulators-of limited utility when administered individually-can achieve dramatic suppression of tumor growth in rodent xenograft models. The present essay attempts to guide development of MSMTs for prostate cancer. Androgen ablation is a signal-modulating measure already in standard use in the management of delocalized prostate cancer. The additional molecular targets considered here include the type 1 insulin-like growth factor receptor, the epidermal growth factor receptor, mammalian target of rapamycin, NF-kappaB, hypoxia-inducible factor-1alpha, hsp90, cyclooxygenase-2, protein kinase A type I, vascular endothelial growth factor, 5-lipoxygenase, 12-lipoxygenase, angiotensin II receptor type 1, bradykinin receptor type 1, c-Src, interleukin-6, ras, MDM2, bcl-2/bclxL, vitamin D receptor, estrogen receptor-beta, and PPAR-. Various nutrients and phytochemicals suspected to have potential utility in prostate cancer prevention and therapy, but whose key molecular targets are still unknown, might reasonably be incorporated into MSMTs for prostate cancer; these include lycopene, selenium, green tea polyphenols, genistein, and silibinin. MSMTs can be developed systematically by testing various combinations of signal-modulating agents, in concentrations that can feasibly be achieved and maintained clinically, on human prostate cancer cell lines; combinations that appear promising can then be tested in xenograft models and, ultimately, in the clinic. Some signal modulators can increase response to cytotoxic drugs by upregulating effectors of apoptosis. When MSMTs fail to raise the spontaneous apoptosis rate sufficiently to achieve tumor stasis or regression, incorporation of appropriate cytotoxic agents into the regimen may improve the clinical outcome.

Quantitative c-erbB-2 but not c-erbB-1 mRNA expression is a promising marker to predict minor histopathologic response to neoadjuvant radiochemotherapy in oesophageal cancer

We examined the potential of quantitative epidermal growth factor receptor (EGFR, synonym: c-erbB-1) and c-erbB-2 (synonym: HER2/neu) mRNA expression to predict minor or major histopathologic response to neoadjuvant radiochemotherapy (cis-platinum, 5-FU, 36 Gy), followed by radical surgical resection, in patients with oesophageal cancer. Tissue samples were collected by endoscopic biopsy prior to treatment. RNA was isolated from biopsies and quantitative real-time reverse transcriptase–polymerase chain reaction assays were performed to determine c-erbB-1 and c-erbB-2 mRNA expression. Relative expression (tumour/paired normal tissue ratio standardised for β-actin) was calculated for EGFR and c-erbB-2 mRNA. Expression levels were correlated with the objective histopathologic response in resected specimens. Histomorphologic regression was defined as major response when resected specimens contained less than 10% of residual vital tumour cells, or in case a pathologically complete response was achieved. Expression of c-erbB-1 mRNA was not associated with the degree of histomorphological response. In contrast, the relative expression levels of c-erbB-2 mRNA >1 were not associated with major histopathologic responses (sensitivity 41.6%, specificity 100%), and 10 out of 36 (28%) patients could be unequivocally identified, whose tumours did not respond well to the delivered neoadjuvant radiochemotherapy (P<0.01). Quantitative expression levels of c-erbB-2, but not c-erbB-1 mRNA, in pretreatment biopsies appear to predict minor histopathologic response to our neoadjuvant radiochemotherapy protocol. This test could be used to prevent expensive, noneffective and potentially harmful therapies in approximately one-fourth of our patients, and leads to a more individualised type of combined modality treatment.

Estrogen receptor inhibits c-Jun-dependent stress-induced cell death by binding and modifying c-Jun activity in human breast cancer cells

c-Jun, a major component of the AP-1 transcription factor, is either pro- or anti-apoptotic with cellular determinants unknown. Nuclear estrogen receptor (ER), on the other hand, regulates gene expression through both estrogen response elements and AP-1. Here we show that stress stimulates c-Jun phosphorylation and AP-1 activity in both ER+ and ER- human breast cancer cells and only induces cell death in ER- cells, indicating a determinant role of ER in c-Jun/AP-1 activity. The inhibitory effect of ER in stress-induced cell death is confirmed by ER transfection into ER- cells. Furthermore, inhibition of c-Jun activation by a dominant negative c-Jun blocks AP-1 activity in ER+ cells and attenuates stress-induced cell death but not AP-1 activity in ER- cells, suggesting that the c-Jun/AP-1 activity has distinct properties depending on ER status. ER was shown to inhibit stress-induced cell death through its physical interaction with c-Jun. This is because ER binds c-Jun in breast cancer cells, stress treatment further increases the ER-bound phosphorylated c-Jun, and the c-Jun binding-deficient ER mutant fails to protect stress-induced cell death. Together, our studies reveal a novel function of ER in stress response by modification of c-Jun activity.

Particular aspects of platinum compounds used at present in cancer treatment

The history of platinum in cancer treatment began 150 years ago with the first synthesis of cisplatin; but it was not used in the clinic before 30 years ago. Then 3000 derivatives were synthesised and tested, with poor successes: three other derivatives only are available today. Clearly they are not more active, but they are less toxic than cisplatin, although two, carboplatin and nedaplatin, yield a cross-resistance, while one, oxaliplatin, does not. Their mechanisms of action are similar: these four pro-drugs form adducts with DNA, impairing DNA synthesis and repair then. Their pharmacokinetics are complicated since we always measure two overlapping pharmacokinetics: those of the parent compound and of the bound platinum. Cisplatin is now recommended for few cancers, it is replaced by less-toxic carboplatin, and therefore more easily used in combination. Oxaliplatin give interesting results in a number of cancers. The official recommendation in Japan for nedaplatin is head and neck, testicular, lung, oesophageal, ovarian, and cervical cancer.

EGF receptor targeting in therapy-resistant human tumors

The development of resistance against cytotoxic or endocrine therapy limits the number of chemotherapeutic compounds used in the clinic. The receptor for EGF (EGFR) is not only involved in survival signaling, cell migration, metastasis formation and angiogenesis, but also confers reduced responses of tumor cells towards cytotoxic compounds or radiation. Clinical trials designed to combine EGFR inhibitors with standard chemo- or radiation therapy have been successful. Elucidation of some of the molecular mechanisms of EGFR-mediated chemoresistance may lead to novel treatment approaches against molecules linked to EGFR signal transduction. In human breast carcinomas, the presence of EGFR correlates with lack of response towards anti-estrogen therapy suggesting the concomitant inhibition of both the receptors for estrogen and EGF to improve breast cancer therapy.

Enhanced ROS production in oncogenically transformed cells potentiates c-Jun N-terminal kinase and p38 mitogen-activated protein kinase activation and sensitization to genotoxic stress

Many primary tumors as well as transformed cell lines display high sensitivity to chemotherapeutic drugs and radiation. The molecular mechanisms that underlie this sensitivity are largely unknown. Here we show that the sensitization of transformed cells to stress stimuli is due to the potentiation of the c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase pathways. Activation of these pathways by the antitumor drug cis-platin (CDDP) and by other stress agents is markedly enhanced and is induced by lower stress doses in NIH 3T3 cells overexpressing epidermal growth factor receptor, HER1-2 kinase, or oncogenic Ras than in nontransformed NIH 3T3 cells. Inhibition of stress kinase activity by specific inhibitors reduces CDDP-mediated cell death in transformed cells, whereas overactivation of stress kinase pathways augments cells death. Potentiation of stress kinases is a common feature of cells transformed by different oncogenes, including cells derived from human tumors, and is shown here to be independent of the activity of the particular transforming oncoprotein. We further show that the mechanism that underlies potentiation of stress kinases in transformed cells involves reactive oxygen species (ROS), whose production is elevated in these cells. JNK/p38 activation is inhibited by antioxidants and in particular by inhibitors of the mitochondrial respiratory chain and NADPH oxidase. Conversely, by artificially elevating ROS levels in nontransformed NIH 3T3 cells we were able to induce potentiation of JNK/p38 activation. Taken together, our findings suggest that ROS-dependent potentiation of stress kinase pathways accounts for the sensitization of transformed cells to stress and anticancer drugs.

Apoptotic cell death in mammary adenocarcinoma cells is prevented by soluble factors present in the target organ of metastasis

Target organ of metastasis determines the fate of metastasis. The soluble factors released from one or more cell types in the new stroma may influence growth and survival of metastatic cells. In the present study, we used conditioned media from the kidney, liver and lung, the latter being the target organ of metastasis of murine mammary adenocarcinoma cell lines LM3, LMM3 and F3II, to assess whether the soluble factors released from these organs could modulate in vitro survival of these cell lines after apoptosis-inducing treatments and to investigate the mechanisms involved in this effect. We demonstrate that conditioned medium from lung, but not from liver or kidney, promotes survival of these cells after doxorubicin, cisplatin, agonistic anti-Fas antibody and serum withdrawal treatments. Furthermore, LMM3 cells treated with lung conditioned medium after doxorubicin exposure maintained their tumorigenic capacity and metastatic potential. Neither IGF nor EGF could promote survival but, surprisingly, TGF-beta could reduce sensitivity of LMM3 cells to doxorubicin in vitro. Doxorubicin treatment induced Bax expression and down-regulated Bcl-2 expression. In contrast, lung conditioned medium increased Bcl-2 expression and inhibited doxorubicin-mediated Bcl-2 down-regulation. Neither of those treatments alone modified Bcl-X(L) expression, although co-treatment induced a 3- to 5-fold increase of its expression. These results suggest that the lung microenvironment could promote metastasis of these adenocarcinoma cell lines by increasing survival of metastatic cells, possibly by modulation of Bcl-2 protein family expression.

Epidermal growth factor receptor tyrosine kinase as a target for anticancer therapy

Increasing knowledge of the structure and function of the epidermal growth factor receptor (EGFR) subfamily of tyrosine kinases and of their role in the initiation and progression of various cancers has, in recent years, provided the impetus for a substantial research effort aimed at developing new anticancer therapies that target specific components of the EGFR signal transduction pathway. Selective compounds have been developed that target either the extracellular ligand-binding region of the EGFR or the intracellular tyrosine kinase region, resulting in interference with the signalling pathways that modulate mitogenic and other cancer-promoting responses (e.g. cell motility, cell adhesion, invasion and angiogenesis). Potential new anticancer agents that target the extracellular ligand-binding region of the receptor include a number of monoclonal antibodies, immunotoxins and ligand-binding cytotoxic agents. Agents that target the intracellular tyrosine kinase region include small molecule tyrosine kinase inhibitors (TKIs), which act by interfering with ATP binding to the receptor, and various other compounds that act at substrate-binding regions or downstream components of the signalling pathway. Currently, the most advanced of the newer therapies undergoing clinical development are antireceptor monoclonal antibodies (e.g. trastuzumab and cetuximab) and a number of small molecule EGFR-TKIs principally of the quinazoline and pyrazolo-pyrrolo-pyridopyrimidine inhibitor structural classes. The latter group of compounds offers several advantages in cancer chemotherapy, including the possibility of inhibiting specific deregulated pathways in cancer cells while having minimal effects on normal cell function. They also have favourable pharmacokinetic and pharmacodynamic properties and low toxicity, and some TKIs such as the reversible inhibitor ZD1839 ('Iressa') are now undergoing phase II to III clinical trials. In addition, the accumulation of evidence from laboratory studies strongly suggests that EGFR-selective TKIs will have synergistic effects with other antitumour agents or therapy such as cytostatic agents, conventional cytotoxic drugs and radiotherapy. As our knowledge of signal transduction pathways in cancer increases, it is hoped that further advances in this area will allow the therapeutic potential of these compounds as anticancer agents to be realised.

Requirement for ERK activation in cisplatin-induced apoptosis

Cisplatin activates multiple signal transduction pathways involved in coordinating cellular responses to stress. Here we demonstrate a requirement for extracellular signal-regulated protein kinase (ERK), a member of the mitogen-activated protein kinase family in mediating cisplatin-induced apoptosis of human cervical carcinoma HeLa cells. Cisplatin treatment resulted in dose- and time- dependent activation of ERK. That elevated ERK activity contributed to cell death by cisplatin was supported by several observations: 1) PD98059 and U0126, chemical inhibitors of the MEK/ERK signaling pathway, prevented apoptosis; 2) pretreatment of cells with TPA, an activator of the ERK pathway, enhanced their sensitivity to cisplatin; 3) suramin, a growth factor receptor antagonist that greatly suppressed ERK activation, likewise inhibited cisplatin-induced apoptosis; and, finally, 4) HeLa cell variants selected for cisplatin resistance showed reduced activation of ERK following cisplatin treatment. Cisplatin-induced apoptosis was associated with cytochrome c release and subsequent caspase-3 activation, both of which could be prevented by treatment with the MEK inhibitors. However, the caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone protected HeLa cells against apoptosis without affecting ERK activation. Taken together, our findings suggest that ERK activation plays an active role in mediating cisplatin-induced apoptosis of HeLa cells and functions upstream of caspase activation to initiate the apoptotic signal.

An analysis of the therapeutic efficacy of protracted infusion of low-dose 5-fluorouracil and cisplatin in advanced gastric cancer

To analyze the clinical efficacy of a protracted infusion of low-dose 5-fluorouracil (5-FU) and cisplatin (CDDP), a phase II study was performed in 36 patients with advanced gastric cancer. The treatment schedule of the low-dose administration of 5-FU and CDDP (FP) was a continuous infusion of 5-FU (250 mg/m2) for 28 consecutive days and a drip infusion of CDDP (3.5 mg/m2) for 5 consecutive days, followed by a 2-day interval each week in one cycle. The overall response rate was 47.2%. Of importance, the improvement in quality of life assessed by performance status (PS) and oral intake was 13.9% and 33.3%, respectively. The toxicity in low-dose FP treatment was less than grade 2, including gastrointestinal toxicities and bone marrow suppression, and this was tolerable during the treatment. The median survival time (MST) and 1-year survival rate were 8 months and 36.2%, respectively. In a pharmacokinetic analysis following the protracted infusion of low-dose FP, the plasma concentrations of 5-FU and CDDP were increased to about 120-130 ng/ml and 0.3-0.5 microg/ml on day 21 after the treatment, respectively. The plasma concentrations of 5-FU and CDDP were not significantly different between responders and non-responders. The tumor response to low-dose FP treatment was associated with the induction of apoptotic cell death and with the overexpression of apoptosis-related genes, such as Bax and Bcl-Xs, in cancer cells. These results indicate that the protracted infusion of low-dose FP could be a useful regimen for patients with advanced gastric cancer, in terms of the high response rate and low toxicity, possibly leading to the prolongation of survival and improvement in the quality of life.

Effects of HER-2/neu on chemosensitivity of tumor cells

In solid tumors, such as breast and ovarian cancer, the predominant genetic mechanism for oncogene activation is through gene amplification. The HER-2 (also known as ErbB2/c-erbB2/HER-2 / neu) oncogene is the most frequently amplified oncogene in breast cancer and its overexpression is associated with poor clinical outcome. In addition to its role in tumor progression, HER-2 has been implicated in altering tumor cell chemosensitivity to cytotoxic chemotherapy, particularly to anthracyclines. However, sophisticated in vitro studies have recently indicated that HER-2 may not have anything to do with the sensitivity of the cancer cells to cytotoxic drugs. Topoisomerase IIalpha gene is a target gene for many cytotoxic drugs and is located just by the HER-2 at the 17q12-q21. TopoIIalpha amplification and deletion may account for both relative chemosensitivity and resistance to anthracycline-therapy depending on the specific genetic defect at the topoIIalpha locus. Whereas HER-2 is an oncogene that clearly can drive tumor induction and growth, its function as a marker for chemoselection may be due to associated genetic changes in the topoIIalpha gene. Copyright 2000 Harcourt Publishers Ltd.

Blockade of the epidermal growth factor receptor tyrosine kinase suppresses tumorigenesis in MMTV/Neu + MMTV/TGF-alpha bigenic mice

Overexpression of ErbB-2/Neu has been causally associated with mammary epithelial transformation. Here we report that blockade of the epidermal growth factor receptor (EGFR) kinase with AG-1478 markedly delays breast tumor formation in mouse mammary tumor virus (MMTV)/Neu + MMTV/transforming growth factor alpha bigenic mice. This delay was associated with inhibition of EGFR and Neu signaling, reduction of cyclin-dependent kinase 2 (Cdk2) and mitogen-activated protein kinase (MAPK) activities and cyclin D1, and an increase in the levels of the Cdk inhibitor p27(Kip1). In addition, BrdUrd incorporation into tumor cell nuclei was prevented with no signs of tumor cell apoptosis. These observations prompted us to investigate the stability of p27. Recombinant p27 was degraded rapidly in vitro by untreated but not by AG-1478-treated tumor lysates. Proteasome depletion of the tumor lysates, addition of the specific MEK1/2 inhibitor U-0126, or a T187A mutation in recombinant p27 all prevented p27 degradation. Cdk2 and MAPK precipitates from untreated tumor lysates phosphorylated recombinant wild-type p27 but not the T187A mutant in vitro. Cdk2 and MAPK precipitates from AG-1478-treated tumors were unable to phosphorylate p27 in vitro. These data suggest that increased signaling by ErbB receptors up-regulates MAPK activity, which, in turn, phosphorylates and destabilizes p27, thus contributing to dysregulated cell cycle progression.

Interrelationships between cellular nucleotide excision repair, cisplatin cytotoxicity, HER-2/neu gene expression, and epidermal growth factor receptor level in non-small cell lung cancer cells

Nucleotide excision repair (NER) is a major repair mechanism for DNA lesions induced by cisplatin. Overexpressions of epidermal growth factor receptor (EGFR) and HER-2/neu have been reported to affect the sensitivity of certain human cancer cells to cisplatin, presumably by modification of DNA repair activity through interference with NER. Using an in vitro repair assay, we investigated NER activity of cisplatin-induced DNA lesions in a panel of 16 non-small cell lung cancer (NSCLC) cell lines. The interrelationships between NER activity, cisplatin sensitivity, HER-2/neu expression and EGFR level, were also analyzed. The results showed that high NER activity was closely correlated with cisplatin resistance and high levels of HER-2/neu expression (P<0.05). Analysis of the relationships between EGFR level and each of the other three parameters revealed no statistically significant correlations (all P values were >0.05 by Spearman rank correlation), but a trend of association (all the values of proportion of accordance were > or =62.5% by using a 2x2 contingency table). These results suggest that NER activity may play an important role in the cisplatin resistance of NSCLC cells and there may be an association between enhanced NER activity and high levels of p185neu and probably EGFR in NSCLC cells. The finding that high levels of EGFR showed very little influence on the relationship between p185neu and cisplatin resistance suggests that EGFR may be a less crucial factor in modulating the chemoresistance of NSCLC cells when compared with HER-2/neu.

Expression and function of EGF-related peptides and their receptors in gynecological cancer--from basic science to therapy

EGF-related peptides and their receptors play an important, but not fully understood role, both, in epithelial physiology and pathophysiology but also in human tumor carcinogenesis and tumor behavior, respectively. Overexpression of EGF-related growth factors from normal epithelium to carcinomas has been demonstrated for several human tissues such as breast, endometrium, cervix and ovary. Additionally, the differential overexpression of EGFR or erb B-2 in various malignancies has already proven to be efficacious in stratifying patients with respect to a poor prognosis. These data suggest that EGF-related growth factors, erb B receptors or signaling proteins that function either upstream or downstream from these receptors may represent novel targets for selective tumor therapy. In the future, conventional chemotherapy regimes will ultimately be wedded to more biologically-oriented therapies. One important target for these novel therapeutic approaches in solid tumors will be the EGF-related growth factors and their receptors.

Altered expression of the suppressors PML and p53 in glioblastoma cells with the antisense-EGF-receptor

Gene amplification and enhanced expression of the epidermal growth factor receptor (EGFR) represent the major molecular genetic alteration in glioblastomas and it may play an essential role in cell growth and in the carcinogenic process. On the other hand, the nuclear suppressor proteins PML and p53 are also known to play critical roles in cancer development and in suppressing cell growth. Here we report that, in glioblastoma cells with defective EGFR function, the expressions of both promyelocytic leukaemia (PML) and p53 were altered. Cells that were transfected with the antisense-cDNA of EGFR were found to have more cells in G1 and fewer cells in S phase. In addition, the transfected cells were found to be non-responsive to EGF-induced cell growth. Interestingly, the expression of the suppressors p53 and PML were found to be significantly increased by immunohistochemical assay in the antisense-EGFR cells. Moreover, the PML expression in many of the cells was converted from the nuclear dot pattern into fine-granulated staining pattern. In contrast, the expressions of other cell cycle regulated genes and proto-oncogene, including the cyclin-dependent kinase 4 (cdk4), retinoblastoma, p16INK4a and p21H-ras, were not altered. These data indicate that there are specific inductions of PML and p53 proteins which may account for the increase in G1 and growth arrest in antisense-EGFR treated cells. It also indicates that the EGF, p53 and PML transduction pathways were linked and they may constitute an integral part of an altered growth regulatory programme. The interactions and cross-talks of these critical molecules may be very important in regulating cell growth, differentiation and cellular response to treatment in glioblastomas.

Asbestos-induced phosphorylation of epidermal growth factor receptor is linked to c-fos and apoptosis

We examined the mechanisms of interaction of crocidolite asbestos fibers with the epidermal growth factor (EGF) receptor (EGFR) and the role of the EGFR-extracellular signal-regulated kinase (ERK) signaling pathway in early-response protooncogene (c-fos/c-jun) expression and apoptosis induced by asbestos in rat pleural mesothelial (RPM) cells. Asbestos fibers, but not the nonfibrous analog riebeckite, abolished binding of EGF to the EGFR. This was not due to a direct interaction of fibers with ligand, inasmuch as binding studies using fibers and EGF in the absence of membranes showed that EGF did not adsorb to the surface of asbestos fibers. Exposure of RPM cells to asbestos caused a greater than twofold increase in steady-state message and protein levels of EGFR (P < 0.05). The tyrphostin AG-1478, which inhibits the tyrosine kinase activity of the EGFR, but not the tyrphostin A-10, which does not affect EGFR activity, significantly ameliorated asbestos-induced increases in mRNA levels of c-fos but not of c-jun. Pretreatment of RPM cells with AG-1478 significantly reduced apoptosis in cells exposed to asbestos. Our findings suggest that asbestos-induced binding to EGFR initiates signaling pathways responsible for increased expression of the protooncogene c-fos and the development of apoptosis. The ability to block asbestos-induced elevations in c-fos mRNA levels and apoptosis by small-molecule inhibitors of EGFR phosphorylation may have therapeutic implications in asbestos-related diseases.

A role for intracellular immunization in chemosensitization of tumor cells?

Acquired drug resistance represents a major cause of chemotherapy failure in patients with cancer. The characterization of the molecular pathways involved in drug resistance has provided us with new targets to overcome this problem. Many of these target proteins are often overexpressed in human cancers. A number of gene therapy strategies, including antisense oligonucleotides, ribozymes and single-chain antibodies, have been developed to achieve the selective modulation and inhibition of various cellu- lar proteins. Thus, these approaches can be exploited to modulate the resistance phenotype of tumor cells. These gene therapy strategies represent a novel and unique way to enhance the sensitivity of tumor cells to chemotherapeutic drugs. This review will focus on the use of intracellular immunization as a means to modulate the expression of specific genetic determinants involved in the drug resistance phenotype.

Transfection of anti-sense complementary DNA of human epidermal-growth-factor receptor attenuates the proliferation of human non-small-cell-lung-cancer cells

The proliferation of human non-small-cell-lung-cancer (NSCLC) cells is regulated by the epidermal-growth-factor-receptor (EGFR)-mediated autocrine loop that interacts with transforming growth factor-alpha (TGF-alpha) of autocrine or paracrine origin. We have shown that EGFR expression is elevated in the brain metastatic variant of human NSCLC cells H226Br, which thereby acquire their increased sensitivity toward exogenous TGF-alpha. To determine detailed cell-phenotype changes as a result of EGFR down-regulation, H226Br cells were transfected with a human EGFR-cDNA construct encompassing an N-terminal fragment (1.8 kb) in anti-sense orientation downstream of the cytomegalovirus (CMV) promoter. The EGFR transcript expressed in the 3'-5' direction is expected to neutralize EGFR mRNA and to reduce protein expression correspondingly. The established cell lines resistant to G418 were shown integrated with the transfected construct and their proliferation rates reduced as compared with the parental cells and with those transfected with vector alone. Down-regulated EGFR expression in cells with the anti-sense construct can be confirmed by Scatchard analysis and suppressed EGFR kinase activity. The restrained-growth phenotype is also demonstrated in the prolonged G2-M phase during the cell cycle, and correlated with impairment of cell proliferation. This finding suggests that EGFR over-expression is critical in maintaining the malignant phenotype of NSCLC cells, thereby providing a valuable biomarker and potential target prevention for lung-cancer-cell proliferation.