Understanding the effect of mechanical forces on ovarian cancer progression

OBJECTIVE

Mechanical forces including tension, compression, and shear stress are increasingly implicated in tumor progression and metastasis. Understanding the mechanisms behind epithelial ovarian cancer (EOC) progression and metastasis is critical, and this study aimed to elucidate the effect of oscillatory and constant tension on EOC.

METHODS

SKOV-3 and OVCAR-8 EOC cell lines were placed under oscillatory tension for 3 days and compared to cells placed under no tension. Cell proliferation, migration, and invasion were analyzed while RNAseq and Western Blots helped investigate the biological mechanisms underlying the increasingly aggressive state of the experimental cells. Finally, in vivo experiments using SCID mice assisted in confirming the in vitro results.

RESULTS

Oscillatory tension (OT) and constant tension (CT) significantly increased SKOV-3 proliferation, while OT caused a significant increase in proliferative genes, migration, and invasion in this cell line. CT did not cause significant increases in these areas. Neither OT nor CT increased proliferation or invasion in OVCAR-8 cells, while both tension types significantly increased cellular migration. Two proteins involved in metastasis, E-cadherin and Snail, were both significantly affected by OT in both cell lines, with E-cadherin levels decreasing and Snail levels increasing. In vivo, tumor growth and weight for both cell types were significantly increased, and ascites development was significantly higher in the experimental OVCAR-8 group than in the control group.

CONCLUSIONS

This study found that mechanical forces are influential in EOC progression and metastasis. Further analysis of downstream mechanisms involved in EOC metastasis will be critical for improvements in EOC treatment.

Anti-NaPi2b antibody-drug conjugate lifastuzumab vedotin (DNIB0600A) compared with pegylated liposomal doxorubicin in patients with platinum-resistant ovarian cancer in a randomized, open-label, phase II study

Background

Lifastuzumab vedotin (LIFA) is a humanized anti-NaPi2b monoclonal antibody conjugated to a potent antimitotic agent, monomethyl auristatin E, which inhibits cell division by blocking the polymerization of tubulin. This study is the first to compare an antibody-drug conjugate (ADC) to standard-of-care in ovarian cancer (OC) patients.

Patients and methods

Platinum-resistant OC patients were randomized to receive LIFA [2.4 mg/kg, intravenously, every 3 weeks (Q3W)] or pegylated liposomal doxorubicin (PLD) (40 mg/m2, intravenously, Q4W). NaPi2b expression and serum CA-125 and HE4 levels were assessed. The primary end point was progression-free survival (PFS) in intent-to-treat (ITT) and NaPi2b-high patients.

Results

Ninety-five patients were randomized (47 LIFA; 48 PLD). The stratified PFS hazard ratio was 0.78 [95% confidence interval (95% CI), 0.46-1.31; P = 0.34] with a median PFS of 5.3 versus 3.1 months (LIFA versus PLD arm, respectively) in the ITT population, and 0.71 (95% CI, 0.40-1.26; P = 0.24) with a median PFS of 5.3 months versus 3.4 months (LIFA versus PLD arm, respectively) in NaPi2b-high patients. The objective response rate was 34% (95% CI, 22% to 49%, LIFA) versus 15% (95% CI, 7% to 28%, PLD) in the ITT population (P = 0.03), and 36% (95% CI, 22% to 52%, LIFA) versus 14% (95% CI, 6% to 27%, PLD) in NaPi2b-high patients (P = 0.02). Toxicities included grade ≥3 adverse events (AEs) (46% LIFA; 51% PLD), serious AEs (30% both arms), and AEs leading to discontinuation of drug (9% LIFA; 8% PLD). Five (11%) LIFA versus 2 (4%) PLD patients had grade ≥2 neuropathy.

Conclusion

LIFA Q3W was well tolerated and improved objective response rate with a modest, nonstatistically significant improvement of PFS compared with PLD in platinum-resistant OC. While the response rate for the monomethyl auristatin E-containing ADC was promising, response durations were relatively short, thereby highlighting the importance of evaluating both response rates and duration of response when evaluating ADCs in OC.

Clinical trials.gov

NCT01991210.

Final report on serial phase II trials of all-intraperitoneal chemotherapy with or without bevacizumab for women with newly diagnosed, optimally cytoreduced carcinoma of Müllerian origin

BACKGROUND

Intraperitoneal (IP) chemotherapy can improve outcomes for women with optimally cytoreduced epithelial ovarian cancer but toxicities are a concern. We conducted 2 phase 2 trials of an IV/IP regimen using carboplatin and paclitaxel without (Trial A) and with bevacizumab (Trial B).

METHODS

Both trials consisted of carboplatin AUC 6 day 1, and paclitaxel 60 mg/m² on days 1,8, 15 of a 21-day cycle; in Trial B, patients received IV bevacizumab 15 mg/kg every cycle starting cycle 2. Chemotherapy was administered IV for cycle 1 and then IP for all subsequent cycles. Primary objectives included safety and tolerability, pathologic CR rate (Trial A), and the rate of completion of IP cycles of therapy (Trial B). Progression-free (PFS), overall survival (OS), and pharmacokinetic analysis were secondary endpoints.

RESULTS

81 patients were treated on both trials (n = 40 and 41 in trials A and B, respectively). Median age for trials A and B was 59 (range, 36-76) and 55 (range, 19-69) years, respectively. 68% and 85% of patients, respectively for A and B, completed at least 4 cycles of treatment in both trials. Treatment with bevacizumab resulted in higher rates of grade 3 fatigue (37 versus 33%) and grade 3-4 diarrhea (22 versus 8%). Median PFS was 23.5 (95%CI 16.2-35.3) and 25 (95%CI 16.4-42.7) months, respectively; median OS was 68 (95%CI 49.5-NR) and 79.7 (95%CI 59.0-79.7) months, respectively for Trial A and B.

CONCLUSIONS

Weekly administered IP carboplatin and IP paclitaxel is tolerable and safe with similar activity with and without concommittant bevacizumab in these 2 trials.

How can molecular abnormalities influence our clinical approach

Background

Despite improvements in diagnostics and treatment, the clinical outcome of epithelial ovarian cancer remains poor over the last three decades. Recent high-throughput genomic studies have demonstrated ovarian cancer as a highly heterogeneous entity with distinctive molecular signatures among different or even within the same histotype. In this article, we review the molecular genetics of epithelial ovarian cancer and how they have been translated into modern clinical trials, as well as their implications in patient stratification for more targeted and personalized approaches.

Patients and methods

Multiple genomic studies were collected to summarize the major advances in understanding ovarian cancer-associated molecular abnormalities with emphasis on their potential clinical applicability to rationalize the design of recent clinical trials.

Results

The clinical management of ovarian cancer can significantly benefit from comprehensive molecular profiling studies, which have uncovered the distinctiveness of ovarian cancer subsets bearing characteristic genomic aberrance and consequentially dysregulated genes and pathways underlying the tumor progression and chemoresistance. Genomics studies have demonstrated a powerful tool to delineate the molecular basis responsible for diverse clinical behaviors associated with tumor histology and grade. In addition, molecular signatures obtained by integrated 'omics' analyses have promised opportunities for novel therapeutic or stratification biomarkers to tailor current clinical management as well as novel predictive tools of clinical end points including patient prognosis and therapeutic efficacy.

Conclusions

Recent progress in understanding the molecular landscape of ovarian cancer has profoundly shifted the design of clinical trials from empirical, unitary paradigms to more rationalized and personalized regimes. Correspondingly, a promising prospective has emerged for ovarian cancer patients to have considerably improved outcome upon careful alignment of patient characteristics, therapeutic biomarkers and targeting approaches. Nevertheless, extensive validation and inference of potential biomarkers are pressing demands on both bioinformatic and biological levels to warrant sufficient clinical relevance for potential translation, so that the performance of related clinical trial can be well predicted and achieved.

Phase I study of safety and pharmacokinetics of the anti-MUC16 antibody-drug conjugate DMUC5754A in patients with platinum-resistant ovarian cancer or unresectable pancreatic cancer

BACKGROUND

MUC16 is a tumor-specific antigen overexpressed in ovarian (OC) and pancreatic (PC) cancers. The antibody-drug conjugate (ADC), DMUC5754A, contains the humanized anti-MUC16 monoclonal antibody conjugated to the microtubule-disrupting agent, monomethyl auristatin E (MMAE).

PATIENTS AND METHODS

This phase I study evaluated safety, pharmacokinetics (PK), and pharmacodynamics of DMUC5754A given every 3 weeks (Q3W, 0.3-3.2 mg/kg) or weekly (Q1W, 0.8-1.6 mg/kg) to patients with advanced recurrent platinum-resistant OC or unresectable PC. Biomarker studies were also undertaken.

RESULTS

Patients (66 OC, 11 PC) were treated with DMUC5754A (54 Q3W, 23 Q1W). Common related adverse events (AEs) in >20% of patients (all grades) over all dose levels were fatigue, peripheral neuropathy, nausea, decreased appetite, vomiting, diarrhea, alopecia, and pyrexia in Q3W patents, and nausea, vomiting, anemia, fatigue, neutropenia, alopecia, decreased appetite, diarrhea, and hypomagnesemia in Q1W patients. Grade ≥3-related AE in ≥5% of patients included neutropenia (9%) and fatigue (7%) in Q3W patients, and neutropenia (17%), diarrhea (9%), and hyponatremia (9%) in Q1W patients. Plasma antibody-conjugated MMAE (acMMAE) and serum total antibody exhibited non-linear PK across tested doses. Minimal accumulation of acMMAE, total antibody, or unconjugated MMAE was observed. Confirmed responses (1 CR, 6 PRs) occurred in OC patients whose tumors were MUC16-positive by IHC (2+ or 3+). Two OC patients had unconfirmed PRs; six OC patients had stable disease lasting >6 months. For CA125, a cut-off of ≥70% reduction was more suitable for monitoring treatment response due to the binding and clearance of serum CA125 by MUC16 ADC. We identified circulating HE4 as a potential novel surrogate biomarker for monitoring treatment response of MUC16 ADC and other anti-MUC16 therapies in OC.

CONCLUSIONS

DMUC5754A has an acceptable safety profile and evidence of anti-tumor activity in patients with MUC16-expressing tumors. Objective responses were only observed in MUC16-high patients, although prospective validation is required.

CLINICAL TRIAL NUMBER

NCT01335958.

Epithelial ovarian cancer: the molecular genetics of epithelial ovarian cancer

BACKGROUND

Epithelial ovarian cancer (EOC) remains one of the leading causes of cancer-related deaths among women worldwide, despite gains in diagnostics and treatments made over the last three decades. Existing markers of ovarian cancer possess very limited clinical relevance highlighting the emerging need for identification of novel prognostic biomarkers as well as better predictive factors that might allow the stratification of patients who could benefit from a more targeted approach.

PATIENTS AND METHODS

A summary of molecular genetics of EOC.

RESULTS

Large-scale high-throughput genomic technologies appear to be powerful tools for investigations into the genetic abnormalities in ovarian tumors, including studies on dysregulated genes and aberrantly activated signaling pathways. Such technologies can complement well-established clinical histopathology analysis and tumor grading and will hope to result in better, more tailored treatments in the future. Genomic signatures obtained by gene expression profiling of EOC may be able to predict survival outcomes and other important clinical outcomes, such as the success of surgical treatment. Finally, genomic analyses may allow for the identification of novel predictive biomarkers for purposes of treatment planning. These data combined suggest a pathway to progress in the treatment of advanced ovarian cancer and the promise of fulfilling the objective of providing personalized medicine to women with ovarian cancer.

CONCLUSIONS

The understanding of basic molecular events in the tumorigenesis and chemoresistance of EOC together with discovery of potential biomarkers may be greatly enhanced through large-scale genomic studies. In order to maximize the impact of these technologies, however, extensive validation studies are required.

Clinicopathologic characteristics associated with long-term survival in advanced epithelial ovarian cancer: an NRG Oncology/Gynecologic Oncology Group ancillary data study

OBJECTIVE

To identify clinicopathologic factors associated with 10-year overall survival in epithelial ovarian cancer (EOC) and primary peritoneal cancer (PPC), and to develop a predictive model identifying long-term survivors.

METHODS

Demographic, surgical, and clinicopathologic data were abstracted from GOG 182 records. The association between clinical variables and long-term survival (LTS) (>10years) was assessed using multivariable regression analysis. Bootstrap methods were used to develop predictive models from known prognostic clinical factors and predictive accuracy was quantified using optimism-adjusted area under the receiver operating characteristic curve (AUC).

RESULTS

The analysis dataset included 3010 evaluable patients, of whom 195 survived greater than ten years. These patients were more likely to have better performance status, endometrioid histology, stage III (rather than stage IV) disease, absence of ascites, less extensive preoperative disease distribution, microscopic disease residual following cyoreduction (R0), and decreased complexity of surgery (p<0.01). Multivariable regression analysis revealed that lower CA-125 levels, absence of ascites, stage, and R0 were significant independent predictors of LTS. A predictive model created using these variables had an AUC=0.729, which outperformed any of the individual predictors.

CONCLUSIONS

The absence of ascites, a low CA-125, stage, and R0 at the time of cytoreduction are factors associated with LTS when controlling for other confounders. An extensively annotated clinicopathologic prediction model for LTS fell short of clinical utility suggesting that prognostic molecular profiles are needed to better predict which patients are likely to be long-term survivors.

A SNaPshot of potentially personalized care: Molecular diagnostics in gynecologic cancer

BACKGROUND

Genetic abnormalities underlie the development and progression of cancer, and represent potential opportunities for personalized cancer therapy in Gyn malignancies.

METHODS

We identified Gyn oncology patients at the MGH Cancer Center with tumors genotyped for a panel of mutations by SNaPshot, a CLIA approved assay, validated in lung cancer, that uses SNP genotyping in degraded DNA from FFPE tissue to identify 160 described mutations across 15 cancer genes (AKT1, APC, BRAF, CTNNB1, EGFR, ERBB2, IDH1, KIT, KRAS, MAP2KI, NOTCH1, NRAS, PIK3CA, PTEN, TP53).

RESULTS

Between 5/17/10 and 8/8/13, 249 pts consented to SNaPshot analysis. Median age 60 (29-84) yrs. Tumors were ovarian 123 (49%), uterine 74(30%), cervical 14(6%), fallopian 9(4%), primary peritoneal 13(5%), or rare 16(6%) with the incidence of testing high grade serous ovarian cancer (HGSOC) halving over time. SNaPshot was positive in 75 (30%), with 18 of these (24%) having 2 or 3 (n=5) mutations identified. TP53 mutations are most common in high-grade serous cancers yet a low detection rate (17%) was likely related to the assay. However, 4 of the 7 purely endometrioid ovarian tumors (57%) harbored a p53 mutation. Of the 38 endometrioid uterine tumors, 18 mutations (47%) in the PI3Kinase pathway were identified. Only 9 of 122 purely serous (7%) tumors across all tumor types harbored a 'drugable' mutation, compared with 20 of 45 (44%) of endometrioid tumors (p<0.0001). 17 pts subsequently enrolled on a clinical trial; all but 4 of whom had PIK3CA pathway mutations. Eight of 14 (47%) cervical tumors harbored a 'drugable' mutation.

CONCLUSION

Although SNaPshot can identify potentially important therapeutic targets, the incidence of 'drugable' targets in ovarian cancer is low. In this cohort, only 7% of subjects eventually were treated on a relevant clinical trial. Geneotyping should be used judiciously and reflect histologic subtype and available platform.

Ovarian cancer: genomic analysis

OBJECTIVES

Despite improvements in the management of ovarian cancer patients over the last 30 years, there has been only a minimal improvement in overall survival. While targeted therapeutic approaches for the treatment of cancer have evolved, major challenges in ovarian cancer research persist, including the identification of predictive biomarkers with clinical relevance, so that empirical drug selection can be avoided. In this article, we review published genomic analysis studies including data generated in our laboratory and how they have been incorporated into modern clinical trials in a rational and effective way.

METHODS

Multiple published genomic analysis studies were collected for review and discussion with emphasis on their potential clinical applicability.

RESULTS

Genomic analysis has been shown to be a powerful tool to identify dysregulated genes, aberrantly activated pathways and to uncover uniqueness of subclasses of ovarian tumors. The application of this technology has provided a solid molecular basis for different clinical behaviors associated with tumor histology and grade. Genomic signatures have been obtained to predict clinical end points for patients with cancer, including response rates, progression-free survival, and overall survival. In addition, genomic analysis has provided opportunities to identify biomarkers, which either result in a modification of existing clinical management or to stratification of patients to novel therapeutic approaches designed as clinical trials.

CONCLUSIONS

Genomic analyses have accelerated the identification of relevant biomarkers and extended our understanding of the molecular biology of ovarian cancer. This in turn, will hopefully lead to a paradigm shift from empirical, uniform treatment to a more rational, personalized treatment of ovarian cancers. However, validation of potential biomarkers on both the statistical and biological levels is needed to confirm they are of clinical relevance, in order to increase the likelihood that the desired outcome can be predicted and achieved.

A Gynecologic Oncology Group study of frequent copy number aberrations in DNA repair genes and other genomic regions in stage I serous ovarian cancers

e16504

Background: A proof of principle array-based comparative genomic hybridization (aCGH) analysis was performed in archival formalin-fixed and paraffin-embedded (FFPE) stage I ovarian cancers (EOC) to determine if frequent (>40%) copy number aberrations (CNAs) can be detected in DNA repair genes including the Fanconi anemia complementation group (FANC) and RAD51 families compared with the rest of the genome. Methods: Tumor DNA was isolated from 22 serous cancers from the GOG-175 virtual tissue bank. RPCI 19K BAC arrays were hybridized (GeneTAC HybStation) and scanned (Gene Pix 4200AL Laser Scanner). Spot fluorescence values were quantified using ImaGene, vetted for quality and loess corrected with adjustments for chip-specific spatial effects. The genome was segmented to identify regions with common copy number means (DNAcopy software). Posterior aberration probabilities for the regions were obtained using CGHcall and data was visualized and annotated using iGenomicViewer in R. Results: Several genes associated with the Fanconi DNA-damage response pathway were frequently altered in stage I serous ovarian carcinomas. A RAD51 homology DMC1 was amplified in 55% of the specimens. Genomic losses were observed in FANC-D1 (BRCA2), and RAD51L3 in 41%, and 27% of specimens, respectively. In contrast, frequent genomic losses or gains involved 13q33.1; 13 q21.31; 17p12; 17q22; 18q12.3; 9p11.2; 9p22.2–22.3; 9q33.1; 8p23.2; 21q21.3; and 5q14.2; or 8q24.3; 3q29; 12p11.1; 17q25.1; 17q25.3; 20q13.33; 20q11.21; 20q11.23; 19p13.13; and 19p13.2, respectively. Conclusions: The GOG-0175 virtual tissue bank yielded high quality DNA for detecting and mapping CNAs in archival FFPE specimens with high resolution. Frequent genomic losses and gains were observed in DNA repair genes and other genomic regions in stage I serous ovarian cancer which may promote genomic instability, resistance, metastasis and aggressiveness of this disease.

No significant financial relationships to disclose.

Simultaneous blockade of AP-1 and phosphatidylinositol 3-kinase pathway in non-small cell lung cancer cells

c-Jun is a major constituent of AP-1 transcription factor that transduces multiple mitogen growth signals, and it is frequently overexpressed in non-small cell lung cancers (NSCLCs). Earlier, we showed that blocking AP-1 by the overexpression of a c-Jun dominant-negative mutant, TAM67, inhibited NSCLC cell growth. The phosphatidylinositol 3-kinase (PI3K)/Akt signal transduction pathway is important in transformation, proliferation, survival and metastasis of NSCLC cells. In this study, we used NCI-H1299 Tet-on clone cells that express TAM67 under the control of inducible promoter to determine the effects of inhibition of AP-1 and PI3K on cell growth. The PI3K inhibitor, LY294002, produced a dose-dependent inhibition of growth in H1299 cells and that inhibition was enhanced by TAM67. TAM67 increased dephosphorylation of Akt induced by LY294002 and reduced the TPA response element DNA-binding of phosphorylated c-Jun. TAM67 increased G1 cell cycle blockade induced by LY294002, which was partially associated with cyclin A decrease and p27^Kip1 accumulation. Furthermore, TAM67 and LY294002 act, at least additively, to inhibit anchorage-independent growth of the H1299 cells. These results suggest that AP-1 and PI3K/Akt pathways play an essential role in the growth of some NSCLC cells.

Growth inhibition of non-small cell lung cancer cells by AP-1 blockade using a cJun dominant-negative mutant

cJun, a major constituent of AP-1 transcription factor transducing multiple mitogen growth signals, is frequently overexpressed in non-small cell lung cancers (NSCLCs). The purpose of this study is to determine the effects of AP-1 blockade on the growth of NSCLC cells using a cJun dominant-negative mutant, TAM67. Transiently transfected TAM67 inhibited AP-1 transcriptional activity in NSCLC cell lines, NCI-H1299 (H1299), A549 and NCI-H520 (H520). The colony-forming efficiency of H1299 and A549 was reduced by TAM67, while that of H520 was not. To elucidate the effects of TAM67 on the growth of H1299, we established H1299 clone cells that expressed TAM67 under the control of a doxycycline-inducible promoter. In the H1299 clone cells, the induced TAM67 inhibited anchorage-dependent growth by promoting G1 cell-cycle block, but not by apoptosis. The induced TAM67 decreased the expression of a cell-cycle regulatory protein, cyclin A. TAM67 also inhibited anchorage-independent growth of these cells. Furthermore, TAM67 reduced growth of established xenograft tumours from these cells in nude mice. These results suggest that AP-1 plays an essential role in the growth of at least some of NSCLC cells.

A stromal-associated gene expression signature predicting for survival in a series of patients with advanced high-grade serous ovarian cancer

5552

Background: Prognostic gene expression signatures have been derived for undissected serous ovarian epithelial tumors, yet the specific contribution of stromal cells to patient survival has not been addressed. The aim of this study is to identify stromal genes impacting patient survival in the context of serous ovarian cancer. Methods: Expression profiling utilizing Affymetrix U133 Plus 2.0 oligonucleotide arrays was completed for 50 microdissected stromal samples derived from high-grade, late-stage serous tumors displaying a broad spectrum of survival endpoints. A semi-supervised dimension reduction method employing multivariate Cox regression and principal components analysis was applied to the expression data to identify genes associated with patient survival and establish a predictive model. qRT-PCR was employed to validate the microarray expression data. Results: Cox regression analysis identified 267 significant genes. The first 6 principal components of these genes, representing >65% of total variance, entered a multivariate Cox model through which the relative hazard of future patients can be predicted. To confirm our finding, the microarray data underwent leave-one-out validation. The patients were equally divided into low- and high-risk groups and non-parametric Kaplan-Meier analysis and log rank test demonstrated the two groups were significantly different in survival (p = 0.0115). Genes associated with cell survival and migration were identified in the prognostic signature. For validation, qRT-PCR data for all 50 specimens was correlated with microarray expression values for a series of select prognostic genes. Conculsions: In this study, we characterized and validated a stromal dervied prognostic signature associated with poor patient survival. Contained in this novel predictor may be stromal targets suitable for the design of new therapeutic interventions, or use as independent diagnostic markers.

No significant financial relationships to disclose.

Use of predictive gene expression signature from advanced-stage serous papillary ovarian cancer to identify biologically relevant molecular targets for chemoresponse

5500

Background: The aim of our study was to develop and validate a gene expression signature predictive for chemoresponse in advanced stage serous papillary ovarian cancer. Methods: Gene expression profiling was performed on 52 chemonaive, microdissected advanced stage, high-grade papillary serous ovarian cancers using Affymetrix whole-genome microarrays. Patient samples were grouped based on chemoresponse. 19 nonresponders were refractory to chemotherapy, 14 responders relapsing 6 months were considered chemosensitive. Each group was divided into training/validation sets. To generate a predictive gene signature, class prediction algorithms were applied to genes differentially expressed between chemosensitive/resistant or chemosensitive/refractory tumors (p<0.001) using leave-one-out cross-validation. Array validation was performed by qRT-PCR. Select genes underwent biological validation in a series of ovarian cancer cell lines. Results: 31 genes predictive for resistance and 105 genes predictive for refractory to chemotherapy were identified. Percentages of arrays accurately predicted in independent validation sets were 90% (9/10) for resistant and 92% (12/13) for refractory gene signatures. Correlations between microarray/qRT-PCR data were robust for both resistant (17/23 genes) and refractory gene signatures (25/34 genes). Data mining of the predictive signatures using PathwayStudio software identified several biological processes (collagen regulation, apoptosis, cell survival, and DNA repair) implicated in conferring resistance to chemotherapy. We transiently transfected RNAi molecules to silence several signature genes and determine their contribution to taxol/cisplatin sensitivity in a series ofl ovarian cancer cell lines. Preliminary data showed DUSP1 gene expression knockdown potentiated cisplatin sensitivity in SKOV3/OVCA429 cell lines, while POLH knockdown potentiated cisplatin sensitivity in OVCA429/OVCA420 cell lines. Conclusions: A gene expression signature predicts for chemoresponse in ovarian cancers, and has identified novel targets of biological/therapeutic interest.

No significant financial relationships to disclose.

RASSF6 is a novel member of the RASSF family of tumor suppressors

RASSF family proteins are tumor suppressors that are frequently downregulated during the development of human cancer. The best-characterized member of the family is RASSF1A, which is downregulated by promoter methylation in 40-90% of primary human tumors. We now identify and characterize a novel member of the RASSF family, RASSF6. Like the other family members, RASSF6 possesses a Ras Association domain and binds activated Ras. Exogenous expression of RASSF6 promoted apoptosis, synergized with activated K-Ras to induce cell death and inhibited the survival of specific tumor cell lines. Suppression of RASSF6 enhanced the tumorigenic phenotype of a human lung tumor cell line. Furthermore, RASSF6 is often downregulated in primary human tumors. RASSF6 shares some similar overall properties as other RASSF proteins. However, there are significant differences in biological activity between RASSF6 and other family members including a discrete tissue expression profile, cell killing specificity and impact on signaling pathways. Moreover, RASSF6 may play a role in dictating the degree of inflammatory response to the respiratory syncytial virus. Thus, RASSF6 is a novel RASSF family member that demonstrates the properties of a Ras effector and tumor suppressor but exhibits biological properties that are unique and distinct from those of other family members.

Identification of molecular markers and signaling pathway in endometrial cancer in Hong Kong Chinese women by genome-wide gene expression profiling

Endometrial cancer is the third most common gynecologic malignancy and the ninth most common malignancy for females overall in Hong Kong. Approximately 80% or more of these cancers are endometrioid endometrial adenocarcinomas. The aim of this study was to reveal genes contributing to the development of endometrioid endometrial cancer, which may impact diagnosis, prognosis and treatment of the disease. Whole-genome gene expression analysis was completed for a set of 55 microdissected sporadic endometrioid endometrial adenocarcinomas and 29 microdissected normal endometrium specimens using the Affymetrix Human U133 Plus 2.0 oligonucleotide microarray. Selected genes of interest were validated by quantitative real-time-polymerase chain reaction (qRT-PCR). Pathway analysis was performed to reveal gene interactions involved in endometrial tumorigenesis. Unsupervised hierarchical clustering displayed a distinct separation between the endometrioid adenocarcinomas and normal endometrium samples. Supervised analysis identified 117 highly differentially regulated genes (>or=4.0-fold change), which distinguished the endometrial cancer specimens from normal endometrium. Twelve novel genes including DKK4, ZIC1, KIF1A, SAA2, LOC16378, ALPP2, CCL20, CXCL5, BST2, OLFM1, KLRC1 and MBC45780 were deregulated in the endometrial cancer, and further validated in an independent set of 56 cancer and 29 normal samples using qRT-PCR. In addition, 10 genes were differentially regulated in late-stage cancer, as compared to early-stage disease, and may be involved in tumor progression. Pathway analysis of the expression data from this tumor revealed an interconnected network consisting of 21 aberrantly regulated genes involved in angiogenesis, cell proliferation and chromosomal instability. The results of this study highlight the molecular features of endometrioid endometrial cancer and provide insight into the events underlying the development and progression of endometrioid endometrial cancer.

N-(4-hydroxyphenyl) retinamide (4HPR) enhances TRAIL-mediated apoptosis through enhancement of a mitochondrial-dependent amplification loop in ovarian cancer cell lines

The majority of ovarian cancer cells are resistant to apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Subtoxic concentrations of the semisynthetic retinoid N-(4-hydroxyphenyl)retinamide (4HPR) enhanced TRAIL-mediated apoptosis in ovarian cancer cell lines but not in immortalized nontumorigenic ovarian epithelial cells. The enhancement of TRAIL-mediated apoptosis by 4HPR was not due to changes in the levels of proteins known to modulate TRAIL sensitivity. The combination of 4HPR and TRAIL enhanced cleavage of multiple caspases in the death receptor pathway (including the two initiator caspases, caspase-8 and caspase-9). The 4HPR and TRAIL combination leads to mitochondrial permeability transition, significant increase in cytochrome c release, and increased caspase-9 activation. Caspase-9 may further activate caspase-8, generating an amplification loop. Stable overexpression of Bcl-xL abrogates the interaction between 4HPR and TRAIL at the mitochondrial level by blocking cytochrome c release. As a consequence, a decrease in activation of caspase-9, caspase-8, and TRAIL-mediated apoptosis occurs. These results indicate that the enhancement in TRAIL-mediated apoptosis induced by 4HPR is due to the increase in activation of multiple caspases involving an amplification loop via the mitochondrial-death pathway. These findings offer a promising and novel strategy for the treatment of ovarian cancer.

The c-Jun NH(2)-terminal protein kinase/AP-1 pathway is required for efficient apoptosis induced by vinblastine

Vinblastine is an important antitumor agent that induces G(2)-M arrest and subsequent apoptosis in a wide variety of cell lines, but the molecular mechanisms that link mitotic arrest and apoptosis are poorly understood. The AP-1 transcription factor has been implicated in many critical cellular processes, including apoptosis, and is a major target of the c-Jun NH(2)-terminal kinase signaling pathway that is activated by vinblastine and other microtubule inhibitors. In this study we sought to determine the role of c-Jun NH(2)-terminal kinase/AP-1 in the response of KB3 carcinoma cells to vinblastine. For this purpose, we generated KB3 cell lines that stably expressed the c-Jun dominant-negative deletional mutant TAM67, which lacks the NH(2)-terminal transactivation domain. KB3-TAM67 cell lines displayed normal growth kinetics and essentially unaltered basal AP-1 activity, but vinblastine-induced phosphorylation of c-Jun and activating transcription factor-2, and AP-1 activation, were strongly inhibited. KB3-TAM67 cell lines arrested normally at G(2)-M in response to vinblastine, but were significantly more resistant to the drug, exhibiting markedly delayed apoptosis and increased overall survival, relative to control cells. To investigate the underlying mechanisms, differential expression of apoptotic regulatory genes was monitored by immunoblot and cDNA microarray analysis. We found that vinblastine treatment caused down-regulation of p53 and its target p21 and up-regulation of tumor necrosis factor alpha, Bak, and several other genes in control but not in KB3-TAM67 cells, identifying these genes as putative targets of vinblastine-inducible AP-1. These results demonstrate that vinblastine-inducible AP-1 plays a destructive, proapoptotic role and may do so by regulating the expression of a specific subset of target genes that promotes efficient apoptotic cell death following mitotic arrest.

Abnormal fragile histidine triad (FHIT) expression in advanced cervical carcinoma: a poor prognostic factor

The FHIT gene is a candidate tumor suppressor gene that has been implicated in the development of cervical carcinoma. We hypothesized that abnormal Fhit expression might be a poor prognostic factor for patients with cervical cancer. The tumors from 59 high-risk patients (stage II-III) were evaluated for abnormal Fhit expression by immunohistochemical staining. Abnormal Fhit expression (absent or reduced) was noted in 66% of the specimens. There was no statistical difference with respect to stage, performance status, para-aortic node metastasis, completion of therapy, grade, race, age, and HIV status between the normal and abnormal Fhit expression groups. The 3-year survival for patients whose tumors displayed normal Fhit expression versus abnormal Fhit expression was 74% versus 37%, respectively. Univariate analysis demonstrated a difference in survival that was statistically significant for age <55 years versus > or =55 years (P = 0.015), normal Fhit expression versus abnormal Fhit expression (P = 0.015), and stage II versus stage III (P = 0.033). Multivariate analysis showed that abnormal Fhit expression was a poor prognostic factor (P = 0.015).

In situ detection of unexpected patterns of mutant p53 gene expression in non-small cell lung cancers

Many solid tumors, including non-small cell lung cancers (NSCLCs), are characterized by heterogenous expression of p53 protein in the neoplastic cells. To analyse the molecular implications of this finding, we examined topographic distribution of p53 mutations using in situ polymerase chain reaction (PCR) in primary NSCLCs, showing distinct patterns of variable p53 overexpression by immunohistochemistry. Unique sets of primers for each mutation were designed, and optimal PCR conditions were determined by standard PCR using DNA from cloned mutants or cell lines established from these tumors. All tumor cell nuclei, regardless of the status of p53 overexpression, demonstrated homogeneous distribution of mutant p53 with specific primers, indicating that only subgroups of the mutated cells overexpressed p53 protein. In situ reverse transcription (RT)-PCR was applied to detect mutant mRNA in the individual tumor cells using specific primers. We found that in each case the distribution of mutant p53 mRNA coincided with that of immunohistochemical overexpression of p53 protein. Our results suggest that the regulation of mutant p53 expression, but not the genotype, is heterogeneous in the neoplastic cells. The topographic genomapping of p53 in NSCLC using in situ PCR provides a novel approach to view molecular mechanisms of lung carcinogenesis.

The role of p27 in endometrial carcinoma

OBJECTIVE

The cyclin-dependent kinase inhibitor p27 has been shown to mediate cell growth arrest in response to various environmental stimuli. p27 protein levels have shown prognostic value in several different types of cancer. We examined the prognostic value of p27 protein expression in endometrial cancer, the most common gynecologic malignancy.

METHODS

A total of 95 paraffin-embedded tumor blocks were obtained and stained via immunohistochemical techniques with a monoclonal antibody against p27. Ten high-power fields were evaluated per slide with at least 1000 cells per slide and two slides per specimen evaluated by two reviewers for nuclear and cytoplasmic staining. The specimens were evaluated for associations with age, stage, grade, and histology. Statistical analysis was performed using the Student t test, chi(2) Kaplan-Meier, and likelihood ratios to assess the data and to generate P values.

RESULTS

A total of 91 patients met inclusion criteria for statistical analysis. Fifty-three patients were stage I, 13 stage II, 14 stage III and 11 stage IV with a positive stain (>50% of cells) for p27 obtained in 32.1, 23.1, 35.7, and 36.4%, respectively (Student t test P = 0.77). Survival data were available on 24 advanced stage patients. p27 protein immunostaining showed no association with patient survival. We also found no association of p27 staining with age or histology. Notably, we found a trend in increasing staining with increase in grade, particularly with stage I patients. Also, there was an association of the nuclear and cytoplasmic staining and stage (P = 0.05), but it had no correlation with patient survival.

CONCLUSION

Our study showed decreased p27 protein staining in endometrial cancers compared to normal endometrial cells. We found that p27 protein staining shows no association with stage, age, or histology and is not prognostic for survival in advanced endometrial cancers. However, there may be a trend associated with increased p27 protein staining with advanced grades of tumors.

Lovastatin induces apoptosis in a primitive neuroectodermal tumor cell line in association with RB down-regulation and loss of the G1 checkpoint

To develop a new approach to the treatment of primitive neuroectodermal tumors we evaluated the effect of the HMG-CoA reductase inhibitor lovastatin on the Ewing's sarcoma cell line CHP-100. Lovastatin induced neural morphology and markers including neuron-specific enolase and neurofilament protein. The acquisition of neural morphology required new mRNA synthesis, and cDNA microarray analysis confirmed that lovastatin altered the program of gene expression. After morphologic differentiation the cells underwent rapidly progressive apoptosis. In normal development of neuronal progenitors, differentiation signals trigger p21WAF1 accumulation, RB hypophosphorylation, enhanced RB-E2F-1 association, and G1 arrest, and these events have been shown to protect from apoptosis. In contrast, in the Ewing's sarcoma cells lovastatin triggered differentiation without causing cell cycle arrest: p21WAF1 was not induced, RB remained hyperphosphorylated, and RB protein expression and RB-E2F-1 association were markedly downregulated, suggesting that loss of an RB-regulated G1 checkpoint promoted apoptosis. Consistent with this hypothesis, adenoviral p21WAF1 decreased DNA synthesis and partially protected from lovastatin-induced cytotoxicity. The data demonstrate a new model for examining the genetic regulation of cell fate in a neural progenitor tumor and suggest a new approach to the treatment of this neoplasm.

Ras uses the novel tumor suppressor RASSF1 as an effector to mediate apoptosis

Although activated Ras proteins are usually associated with driving growth and transformation, they may also induce senescence, apoptosis, and terminal differentiation. The subversion of these anti-neoplastic effects during Ras-dependent tumor development may be as important as the acquisition of the pro-neoplastic effects. None of the currently identified potential Ras effector proteins can satisfactorily explain the apoptotic action of Ras. Consequently, we have sought to identify novel Ras effectors that may be responsible for apoptosis induction. By examining the EST data base, we identified a potential Ras association domain in the tumor suppressor RASSF1. We now show that RASSF1 binds Ras in a GTP-dependent manner, both in vivo and directly in vitro. Moreover, activated Ras enhances and dominant negative Ras inhibits the cell death induced by transient transfection of RASSF1 into 293-T cells. This cell death appears to be apoptotic in nature, as RASSF1-transfected 293-T cells exhibit membrane blebbing and can be rescued by the addition of a caspase inhibitor. Thus, the RASSF1 tumor suppressor may serve as a novel Ras effector that mediates the apoptotic effects of oncogenic Ras.

c-Jun activation-dependent tumorigenic transformation induced paradoxically by overexpression or block of S-adenosylmethionine decarboxylase

All mammalian cells absolutely require polyamines (putrescine, spermidine, and spermine) for growth. Here we show that the overexpression of cDNA for S-adenosylmethionine decarboxylase (AdoMetDC), the main regulatory enzyme in the biosynthesis of higher polyamines, induces transformation of rodent fibroblasts when expressed in the sense or the antisense orientation. Both transformants were able to induce invasive tumors in nude mice. Neither transformation was associated with activation of the mitogen-activated protein kinases Erk1 and Erk2. Instead, the AdoMet DC sense, but not antisense, transformants displayed constitutive activation of the c-Jun NH(2)-terminal kinase (JNK) pathway. However, both transformations converged on persistent phosphorylation of endogenous c-Jun at Ser73. The phenotype of the AdoMetDC sense transformants was reversed by expression of dominant-negative mutants of SEK1 (MKK4), JNK1, and c-Jun (TAM-67), which were also found to impair cytokinesis. Similarly, TAM-67 reverted the morphology of the AdoMetDC-antisense expressors. This report is the first demonstration of a protein whose overexpression or block of synthesis can induce cell transformation. In addition, we show that the polyamine biosynthetic enzymes require c-Jun activation for eliciting their biological effects.

Age-specific survival of women with endometrioid adenocarcinoma of the uterus

OBJECTIVE

The purpose of this paper was to evaluate the age-specific survival for women diagnosed with endometrioid adenocarcinoma of the uterus.

METHODS

A retrospective analysis was conducted of 328 patients diagnosed with endometrioid adenocarcinoma of the uterus between January 1990 and December 1997. Patients were followed for 3 to 96 months with a mean of 43 months. The impact of age on survival was assessed using Cox proportional hazard regression and multivariate analysis for age, stage, and grade. Stage and grade were analyzed using log-rank tests, and survival curves were generated by the Kaplan-Meier method.

RESULTS

A total of 328 patients were evaluated. Multivariate analysis revealed age, stage, and grade were all significant independent predictors of survival (P < 0.0001). Age-specific survival varied from a high of 90% at age 40 to a low of 55% at age 80. Interval age-specific survival decreased below 86% at age 50. Subset analysis of patients younger than 50 compared with older patients revealed no difference in surgical stage or grade of tumors among these patients. Patients older than 50, however, were 41% more likely to receive adjuvant radiation therapy.

CONCLUSION

Age is a specific, significant predictor of outcome in endometrioid adenocarcinoma of the uterus. Survival decreases significantly in patients older than 50. This decreased survival associated with age is unrelated to surgical stage or grade of adenocarcinoma. Decreased survival could involve molecular differences in the developing endometrial cancer or an increased risk of death from other non-cancer-related factors.

Endocervical cancer is associated with an increase in the ligands and receptors for transforming growth factor-beta and a contrasting decrease in p27(Kip1)

OBJECTIVE

The aim of this study was to investigate the relationship between the expression of the TGF-beta ligands and TGF-beta receptors to the expression of p27(Kip1), a TGF-beta-regulated gene, in endocervical cancer.

METHODS

To examine the expression of TGF-beta and p27(Kip1) in malignant transformation of the uterine endocervix, a panel of 23 formalin-fixed and paraffin-embedded human cervical specimens, including 8 with benign endocervical glands, 8 with cervical adenocarcinoma in situ, and 7 with cervical adenocarcinomas, was used. Tissues were immunostained with polyclonal antibodies that react specifically with TGF-beta 1, TGF-beta 2, TGF-beta 3, TGF-beta RI, TGF-beta RII, and p27(Kip1).

RESULTS

Immunostaining for TGF-beta 1, TGF-beta 2, TGF-beta 3, TGF-beta RI, TGF-beta RII, and p27(Kip1) was detected in normal endocervix, with the TGF-betas showing weak cytoplasmic staining, while p27(Kip1) showed strong nuclear staining. Expression of TGF-beta increased significantly upon neoplastic transformation with the TGF-beta ligands and receptors showing strong cytoplasmic staining in adenocarcinoma in situ compared to normal endocervix. Interestingly, expression of TGF-beta was lower in adenocarcinoma than in adenocarcinoma in situ, but still significantly higher than in normal endocervix. TGF-beta 2 and TGF-beta 3 showed higher levels of immunostaining than TGF-beta 1 in adenocarcinomas. In contrast, p27(Kip1) protein expression decreased with progressive malignancy, with lower p27(Kip1) protein levels detected in adenocarcinoma than in adenocarcinoma in situ, while normal endocervix showed the highest level of p27(Kip1) protein expression.

CONCLUSION

Elevated expression of the TGF-beta ligands and receptors is found in both cervical adenocarcinoma in situ and adenocarcinoma compared to normal endocervix. In contrast, a progressive decrease in p27(Kip1) occurs upon neoplastic transformation of the normal endocervix to cervical adenocarcinoma. These results suggest that neoplastic transformation of the endocervix may be related to dysregulation of TGF-beta and p27(Kip1) seen as an elevation of TGF-beta and a reduction of p27(Kip1) expression that may lead to loss of cell cycle control.

p27 and cyclin D1 abnormalities in uterine papillary serous carcinoma

OBJECTIVE

The expression status of p27 and cyclin D1 was examined in 21 uterine papillary serous carcinoma (UPSC) specimens to determine the role of these genes in the development of this disease. The status of p53, p16, Rb, and K-ras was also determined in these tissues so that a marker profile for UPSC could be compared with the published marker profile for other forms of endometrial and ovarian cancer.

METHODS

Immunohistochemistry was performed on 21 UPSC tissue sections to determine the expression status of p27, cyclin D1, p53, p16, and Rb. K-ras mutations were identified by restriction fragment length polymorphism analysis of DNA isolated from the UPSC sections.

RESULTS

All specimens displayed at least one molecular abnormality. A high incidence of p27 alterations were observed, with reduced p27 expression measured in 16 of 21 (76%) tumors, followed by p53 alterations observed in 13 of 21 (62%) tumors. The p27 abnormalities occur at an early stage of the disease, with 63% (5/8) of Stage I cases displaying reduced p27 expression. Cyclin D1 overexpression was observed in 4 of 21 (19%) specimens, whereas p16, Rb, and K-ras abnormalities were each observed in 2 of 21 specimens (10%). Both K-ras mutations were at codon 12. The p16 and Rb abnormalities coexisted in the same specimens.

CONCLUSION

UPSC tumors display a high incidence of p27 abnormalities, suggesting that p27 abnormalities play an important role in the development of this disease. Our results also indicate that cyclin D1 overexpression is involved in the development of a small number of UPSC cases. A comparison of our results with reports by other authors suggests that UPSC shares molecular marker alterations with both ovarian cancer and endometrioid adenocarcinoma.

TNF-alpha gene expression in macrophages: regulation by NF-kappa B is independent of c-Jun or C/EBP beta

The interaction of transcription factors is critical in the regulation of gene expression. This study characterized the mechanism by which NF-kappa B family members interact to regulate the human TNF-alpha gene. A 120-bp TNF-alpha promoter-reporter, possessing binding sites for NF-kappa B (kappa B3), C/EBP beta (CCAAT/enhancer binding protein beta), and c-Jun, was activated by cotransfection of plasmids expressing the wild-type version of each of these transcription factors. Employing adenoviral vectors, dominant-negative versions of NF-kappa B p65, and c-Jun, but not C/EBP beta, suppressed (p < 0.05-0.001) LPS-induced TNF-alpha secretion in primary human macrophages. Following LPS stimulation, NF-kappa B p50/p65 heterodimers bound to the kappa B3 site and c-Jun to the -103 AP-1 site of the TNF-alpha promoter. By transient transfection, NF-kappa B p65 and p50 synergistically activated the TNF-alpha promoter. In contrast, no synergy was observed between NF-kappa B p65, with or without NF-kappa B p50, and c-Jun or C/EBP beta, even in the presence of the coactivator p300. The contribution of the upstream kappa B binding sites was also examined. Following LPS stimulation, the kappa B1 site bound both NF-kappa B p50/p65 heterodimers and p50 homodimers. The binding by NF-kappa B p50 homodimers to the kappa B1, but not to the kappa 3, site contributed to the inability of macrophages to respond to a second LPS challenge. In summary, adjacent kappa B3 and AP-1 sites in the human TNF-alpha promoter contribute independently to LPS-induced activation. Although both the kappa B1 and kappa B3 sites bound transcriptionally active NF-kappa B p50/p65 heterodimers, only the kappa B1 site contributed to down-regulation by NF-kappa B p50 homodimers.

cJun overexpression in MCF-7 breast cancer cells produces a tumorigenic, invasive and hormone resistant phenotype

We have previously demonstrated decreased Jun/AP-1 activity in the breast cancer cell line MCF-7 when compared to normal or immortalized mammary epithelial cells. In this paper, we overexpress Jun in MCF-7 cells (MCF7Jun) and demonstrate that it results in diverse biologic and biochemical changes, which mimic those seen clinically in breast cancer. Overexpression of Jun causes significant alterations in the composition of AP-1, decreased junB and increased fra-1 expression and results in an increased biologic aggressiveness. MCF7Jun cells exhibit increased cellular motility, increased expression of a matrix degrading enzyme MMP-9, increased in vitro chemoinvasion and tumor formation in nude mice in the absence of exogenous estrogens. Furthermore, MCF7Jun cells are unresponsive to the growth stimulating effects of estrogen and growth inhibitory effects of tamoxifen. Analysis of the estrogen receptor (ER) expression and activity showed that the MCF7Jun cells have no detectable ER. MCF-7 cells overexpressing mutant forms of cJun were responsive to the growth stimulatory effects of estrogen indicating that full-length cJun is required to acquire the estrogen-independent phenotype in breast cancer cells.

Abnormal Fhit expression in malignant and premalignant lesions of the cervix

Genetic analysis of cervical cancer has demonstrated frequent allelic loss in the 3p chromosomal region. The newly described gene FHIT is located at chromosome region 3p14.2, and its expression has been demonstrated previously by reverse transcription-PCR to be abnormal in a majority of cervical cancer cell lines. In this study, 98 different lesions of the cervix were examined for Fhit expression by immunohistochemical staining. Whereas normal cervical epithelium demonstrated diffuse, moderate to intense cytoplasmic staining, many pathological lesions of the cervix displayed reduced or absent Fhit expression. Sixty-one percent of squamous carcinomas and 40% of adenocarcinomas of the cervix had abnormal Fhit expression. Sixty-five preneoplastic lesions of the cervix were examined. Eleven of 33 high-grade squamous intraepithelial lesions and 1 of 12 low-grade squamous intraepithelial lesions had abnormal Fhit expression. In summary, Fhit expression is frequently abnormal in both glandular and squamous cervical cancers, with a higher frequency of Fhit alterations observed in squamous lesions. In addition, abnormal Fhit expression can be detected in some preneoplastic lesions of the ectocervix. Alterations in Fhit expression may be an important marker of early progression in the development of cancers of the cervix.

c-Jun triggers apoptosis in human vascular endothelial cells

In endothelial cells (ECs), the transcription factor c-Jun is induced by a variety of stimuli that perturb EC function. To extend our understanding of the role of c-Jun in EC physiology, we have directed overexpression of c-Jun in human umbilical vein ECs by using a tetracycline-regulated adenoviral expression system. In this study, we report a novel observation using this system. Specific expression of c-Jun is a sufficient trigger for ECs to undergo apoptosis, as demonstrated by a set of combined assays including an ELISA specific for histone-associated DNA fragmentation, DNA laddering, and TdT-mediated dUTP nick end labeling (TUNEL). Tetracycline can effectively shut off c-Jun overexpression and prevent EC apoptosis. Cleavage of poly(ADP-ribose) polymerase was also detected in ECs overexpressing c-Jun. Moreover, inhibitors of cysteine proteases blocked the apoptosis, suggesting a caspase-associated mechanism involved in proapoptotic effects of c-Jun. To gain further insight into the role of c-Jun as a pathophysiological regulator of EC death, TAM67, a dominant-negative mutant of c-Jun, was overexpressed in human umbilical vein ECs to abrogate endogenous c-Jun/activator protein-1 activation. H(2)O(2)-triggered apoptosis was largely attenuated in ECs overexpressing TAM67. Together, these results suggest that c-Jun, as a proapoptotic molecule, may play a role in mediating the cell death program in vascular endothelium.

Frequent loss of KAI1 expression in squamous and lymphoid neoplasms. An immunohistochemical study of archival tissues

The metastasis suppressor gene KAI1 was identified by its ability to inhibit the formation of pulmonary metastases in experimental models for prostatic carcinoma. Down-regulation of this gene may be correlated with the invasive phenotype in melanomas and colon and bladder carcinomas and with the metastatic phenotype in carcinomas of the lung, breast, prostate, and pancreas. The goal of our study was to establish an immunohistochemical method to detect KAI1 expression in archival tissues. Using cell lines with known KAI1 levels and paraffin-embedded KAI1 positive tissues as controls, we observed strong membrane staining in lymphoid follicular centers and squamous epithelia. We then demonstrated the utility of our assay by studying KAI1 expression in 34 lymphoid and 57 squamous lesions. All eight reactive lymph nodes were KAI1 positive. In contrast, three of 13 follicular small cleaved and five of 13 diffuse large cell lymphomas were KAI1 negative. Seventy-nine percent (37 of 47) of invasive squamous cell carcinomas from the lung (n = 15), head and neck (n = 18), and cervix (n = 14) showed extensive KAI1 down-regulation. Loss of KAI1 expression was also found in a subset of 10 high-grade cervical dysplasias. Our data show that (i) immunohistochemistry is a suitable technique for evaluating KAI1 expression in archival tissues; (ii) KAI1 was not expressed in a subset of both low-grade and high-grade lymphomas; and (iii) there was extensive down-regulation of KAI1 in squamous cell carcinomas, suggestive of an important role of the gene in the suppression of invasion in these malignancies.

JunB forms the majority of the AP-1 complex and is a target for redox regulation by receptor tyrosine kinase and G protein-coupled receptor agonists in smooth muscle cells

To understand the role of redox-sensitive mechanisms in vascular smooth muscle cell (VSMC) growth, we have studied the effect of N-acetylcysteine (NAC), a thiol antioxidant, and diphenyleneiodonium (DPI), a potent NADH/NADPH oxidase inhibitor, on serum-, platelet-derived growth factor BB-, and thrombin-induced ERK2, JNK1, and p38 mitogen-activated protein (MAP) kinase activation; c-Fos, c-Jun, and JunB expression; and DNA synthesis. Both NAC and DPI completely inhibited agonist-induced AP-1 activity and DNA synthesis in VSMC. On the contrary, these compounds had differential effects on agonist-induced ERK2, JNK1, and p38 MAP kinase activation and c-Fos, c-Jun, and JunB expression. NAC inhibited agonist-induced ERK2, JNK1, and p38 MAP kinase activation and c-Fos, c-Jun, and JunB expression except for platelet-derived growth factor BB-induced ERK2 activation. In contrast, DPI only inhibited agonist-induced p38 MAP kinase activation and c-Fos and JunB expression. Antibody supershift assays indicated the presence of c-Fos and JunB in the AP-1 complex formed in response to all three agonists. In addition, cotransfection of VSMC with expression plasmids for c-Fos and members of the Jun family along with the AP-1-dependent reporter gene revealed that AP-1 with c-Fos and JunB composition exhibited a higher transactivating activity than AP-1 with other compositions tested. All three agonists significantly stimulated reactive oxygen species production, and this effect was inhibited by both NAC and DPI. Together, these results strongly suggest a role for redox-sensitive mechanisms in agonist-induced ERK2, JNK1, and p38 MAP kinase activation; c-Fos, c-Jun, and JunB expression; AP-1 activity; and DNA synthesis in VSMC. These results also suggest a role for NADH/NADPH oxidase activity in some subset of early signaling events such as p38 MAP kinase activation and c-Fos and JunB induction, which appear to be important in agonist-induced AP-1 activity and DNA synthesis in VSMC.

The roles of signaling by the p42/p44 mitogen-activated protein (MAP) kinase pathway; a potential route to radio- and chemo-sensitization of tumor cells resulting in the induction of apoptosis and loss of clonogenicity

During the last 10 years, multiple signal transduction pathways within cells have been discovered. These pathways have been linked to the regulation of many diverse cellular events such as proliferation, senescence, differentiation and apoptosis. This review will focus upon the many roles of signaling by the p42/p44 mitogen-activated protein (MAP) kinase pathway. Recent evidence suggests that signaling by the MAP kinase pathway can both enhance proliferation by increased expression of molecules such as cyclin D1, but also cause growth arrest by increased expression of molecules such as the cyclin kinase inhibitor protein p21(Cip-1/MDA6/WAF1). These differential effects on growth have been correlated to the amplitude and duration of the MAP kinase activity signal. Furthermore several laboratories are reporting data suggesting that inhibition of the MAP kinase pathway, as well as a family of upstream MAP kinase activators, the protein kinase C family, represent an important route to both radio- and chemo-sensitization of tumor cells. Herein, we describe the historical discovery and characterization of the MAP kinase pathway. In addition we describe potential mechanisms by which inhibition of protein kinase C, the MAP kinase pathway, and potentially of p21(Cip-1/MDA6/WAF1) expression, may alter the sensitivities of leukemic and carcinoma cells to cytotoxic insults, leading to increased apoptosis and loss of clonogenicity.

RRR-alpha-tocopheryl succinate induction of prolonged activation of c-jun amino-terminal kinase and c-jun during induction of apoptosis in human MDA-MB-435 breast cancer cells

We have demonstrated that RRR-alpha-tocopheryl succinate (10 microg/mL vitamin E succinate (VES) treatment of estrogen receptor-negative MDA-MB-435 human breast cancer cells induces 9, 19, 51, and 72% apoptotic cells on days 1-4, respectively, after treatment, which involves transforming growth factor-beta signaling. Here, we show that VES-triggered apoptosis of MDA-MB-435 cells induced prolonged elevated expression of c-jun mRNA and protein (neither of which was caused by major increases in stability) and also induced enhanced activator protein-1 (AP-1) binding to the consensus DNA oligomer. Furthermore, VES treatments resulted in increased AP-1 transactivation activity, as measured with an AP-1 promoter/luciferase reporter construct and by the measurement of increased mRNA expression of the AP-1-dependent endogenous gene collagenase. Evidence of VES-induced involvement of the c-jun amino-terminal kinase in these AP-1-dependent events was suggested by data showing prolonged activity of this kinase, as measured by a kinase assay using glutathione S-transferase-c-jun as the substrate. The c-jun-dependent transcriptional activity was verified by cotransfection of a chimeric transcription factor having a galactose 4 DNA-binding domain coupled with the transactivation domain of c-jun plus the reporter plasmid 5X GAL4-luciferase. MDA-MB-435 cells infected with an adenovirus expression vector containing the TAM-67 sequence for dominant/negative-acting mutant c-jun or transiently transfected with c-jun antisense exhibited a 50-77% reduction in VES-mediated apoptosis as compared with control adenovirus-infected or control sense oligomer-transfected cells.

AP1 regulation of proliferation and initiation of apoptosis in erythropoietin-dependent erythroid cells

The transcription factor AP1 has been implicated in the induction of apoptosis in cells in response to stress factors and growth factor withdrawal. We report here that AP1 is necessary for the induction of apoptosis following hormone withdrawal in the erythropoietin (EPO)-dependent erythroid cell line HCD57. AP1 DNA binding activity increased upon withdrawal of HCD57 cells from EPO. A dominant negative AP1 mutant rendered these cells resistant to apoptosis induced by EPO withdrawal and blocked the downregulation of Bcl-XL. JunB is a major binding protein in the AP1 complex observed upon EPO withdrawal; JunB but not c-Jun was present in the AP1 complex 3 h after EPO withdrawal in HCD57 cells, with a concurrent increase in junB message and protein. Furthermore, analysis of AP1 DNA binding activity in an apoptosis-resistant subclone of HCD57 revealed a lack of induction in AP1 DNA binding activity and no change in junB mRNA levels upon EPO withdrawal. In addition, we determined that c-Jun and AP1 activities correlated with EPO-induced proliferation and/or protection from apoptosis. AP1 DNA binding activity increased over the first 3 h following EPO stimulation of HCD57 cells, and suppression of AP1 activity partially inhibited EPO-induced proliferation. c-Jun but not JunB was present in the AP1 complex 3 h after EPO addition. These results implicate AP1 in the regulation of proliferation and survival of erythroid cells and suggest that different AP1 factors may play distinct roles in both triggering apoptosis (JunB) and protecting erythroid cells from apoptosis (c-Jun).