Expression of BAG-1 and BcL-2 proteins before and after neoadjuvant chemotherapy of locally advanced breast cancer

Expression Patterns of Biomarkers in Primary Tumors and Corresponding Metastases in Breast Cancer

Tumor heterogeneity has been shown for several cancers including breast cancer (BC). Despite the fact that expression of tumor markers may change throughout the metastatic process, rebiopsies at the time of recurrence are still not performed routinely at all institutions. The aims of the study were to evaluate changes in biomarker profiles during the metastatic process and to investigate whether previous anthracycline or endocrine therapy given in the adjuvant setting could affect the biomarker profile in metastatic lesions. We investigated the expression pattern of ER, HER2, TOP2a, TOP1, p53, Bcl-2, and Ki-67 in 110 paired samples of primary BC and corresponding asynchronous metastases. We found discordant expressions in primary tumor and metastasis for all biomarkers, although only significant for Ki-67. Changes in the expression profile of the metastatic lesions would have altered treatment decisions in 14% of patients. We found no effect of previous anthracycline or endocrine therapy on the expression profiles. Our data confirm that discordant expressions of biomarkers are common in BC and often carry therapeutic consequences. This emphasizes the need for biopsies from metastatic lesions, even in cases where the localization of the metastatic process is not easily accessible.

Genetic Markers in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) accounts for 15% to 20% of breast cancer cases and is characterized by the absence of estrogen, progesterone, and human epidermal growth factor 2 receptors. Though TNBC is a highly heterogenic and aggressive disease, TNBC patients have better response to neoadjuvant therapy compared to other breast cancer subtypes. Nevertheless, patients with residual disease have a very poor prognosis, with higher probability of relapse and lower overall survival in the first years after diagnosis. TNBC has 6 subtypes with distinct molecular signatures with different prognoses and probably different responses to therapy. The precise stratification of TNBC is therefore crucial for the development of potent standardized and targeted therapies. In spite of intensive research into finding new molecular biomarkers and designing personalized therapeutic approaches, BRCA mutational status is the only clinically validated biomarker for personalized therapy in TNBC. Recent studies have reported several promising biomarkers that are currently being validated through clinical trials. The objective of this review was to summarize the clinically relevant genetic markers for TNBC that could serve as diagnostic, prognostic, or predictive or could improve personalized therapeutic strategies.

BCL2 is an independent predictor of outcome in basal-like triple-negative breast cancers treated with adjuvant anthracycline-based chemotherapy

Neither targeted therapies nor predictors for chemotherapy sensitivity are available for triple-negative breast cancer (TNBC). Our study included 187 patients with TNBC, 164 of whom were treated with anthracycline-based adjuvant chemotherapy. Eleven molecular biomarkers were analyzed. BCL2, epidermal growth factor receptor (EGFR), MYC, TOP2A, and Ki-67 protein expression was evaluated by immunohistochemistry. The status of the EGFR, MYC, and TOP2A genes and chromosomes 7, 8, and 17 was assessed using fluorescence in situ hybridization. High BCL2 expression predicted poor relapse-free survival (RFS) in patients treated with anthracycline-based adjuvant chemotherapy (p = 0.035), poor breast cancer-specific survival (BCSS) (p = 0.048), and a trend to poor overall survival (OS) (p = 0.085). High levels of BCL2 expression predicted poor OS in basal-like (BL) TNBC patients treated with adjuvant anthracycline-based regimens (log-rank p = 0.033, hazard ratio (HR) 3.04, 95 % confidence interval (CI) 1.04-8.91) and a trend to poor RFS (log-rank p = 0.079) and poor BCSS (log-rank p = 0.056). Multivariate analysis showed that BCL2 status, tumor size, and nodal status all had independent predictive significance for RFS (p = 0.005, p = 0.091, p = 0.003, respectively; likelihood ratio test for the whole model, p = 0.003), BCSS (p = 0.012, p = 0.077, p = 0.01, respectively; likelihood ratio test for the whole model, p = 0.016), and OS (p = 0.008, p = 0.004, p = 0.004, respectively; likelihood ratio test for the whole model, p = 0.0006). Similarly, multivariate analysis for BL TNBC showed BCL2, tumor size, and nodal status all had independent predictive significance for RFS (likelihood ratio test for the whole model, p = 0.00125), BCSS (p = 0.00035), and OS (p = 0.00063). High EGFR expression was associated with poor BCSS (p = 0.039) in patients treated with anthracycline-based adjuvant chemotherapy. Patients who underwent anthracycline-based adjuvant chemotherapy and exhibited CMYC amplification had a trend to worse BCSS (p = 0.066). In conclusion, high BCL2 expression is a significant independent predictor of poor outcome in TNBC patients treated with anthracycline-based adjuvant chemotherapy, and this is the first study showing the BCL2 prediction in BL TNBC. BCL2 expression analysis could facilitate decision making on adjuvant treatment in TNBC patients.

Bcl-2 expression predicts sensitivity to chemotherapy in breast cancer: a systematic review and meta-analysis

Background

Numerous studies have yielded inconclusive results regarding the relationship between anti-apoptotic protein Bcl-2 expression and the sensitivity to chemotherapy in the patients with breast cancer. The purpose of the current study was therefore to elaborate their relationship.

Methods, findings

A total of 23 previously published eligible studies involving 2,467 cases were identified and included in this meta-analysis. Negative Bcl-2 expression was associated with good chemotherapy response in breast cancer patients (total objective response [OR]: risk ratio [RR] = 1.16, 95% confidence interval [CI] = 1.02-1.32, p = 0.026; total complete response [CR]: RR = 1.67, 95% CI = 1.24-2.24, p = 0.001; pathological CR: RR = 1.92, 95% CI = 1.38-2.69, p < 0.001). In further stratified analyses, this association remained for sub-groups of response in neoadjuvant chemotherapy setting, especially pathological CR. Besides, negative Bcl-2 expression was significantly associated with good OR and pathological CR in anthracycline-based chemotherapy subgroup. Furthermore, there were significant links between negative Bcl-2 expression and taxane-based chemotherapy with pathological CR, but not OR.

Conclusion

The results of the present meta-analysis suggest that Bcl-2 expression is a predictive factor for chemotherapy sensitivity in breast cancer patients. They could also potentially benefit further clinical treatment for breast cancers.

Clinical implications of chemotherapy-induced tumor gene expression in human breast cancers

IMPORTANCE OF THE FIELD

There has been much interest in generating gene signatures to predict treatment response in breast cancer.

AREAS COVERED IN THIS REVIEW

There are at least 15 published studies that describe baseline tumor gene signatures predicting chemotherapy sensitivity. As an extension of these baseline studies, there have been at least 8 published studies evaluating chemotherapy-induced tumor genomic changes over time in human breast cancers.

WHAT THE READER WILL GAIN

Studies on chemotherapy-induced gene expression changes were reviewed in detail. Drug-induced biological changes within the tumor shed light on mechanisms of drug resistance and provided valuable insights regarding genes and pathways that were regulated by different drugs, including therapeutic targets that could be exploited to overcome resistance. One study also suggested post-chemotherapy gene signatures to be more predictive of response and survival than the unchallenged baseline signatures.

TAKE HOME MESSAGE

Studies on chemotherapy-induced changes, although informative, are logistically demanding to execute, often with significant attrition of collected samples resulting in small datasets. They are further limited by heterogeneity of study population, chemotherapy regimens used, timing of the post-therapy sample and definition of response endpoint, making cross-comparisons of studies and data interpretation difficult. Future studies should address these limitations, and should involve larger sample sets and prospective studies for validation.

Chemotherapy-induced tumor gene expression changes in human breast cancers

OBJECTIVE

Studying chemotherapy-induced gene expression changes in vivo, which could provide insights into mechanisms of chemotherapy resistance.

METHODS

We analyzed and compared tumor gene expression changes of about 38 500 genes before and 3 weeks after doxorubicin or docetaxel treatment in 47 breast cancer patients.

RESULTS

By using the median expression level of each probe set as the parameter, less than 5% of genes were upregulated or downregulated by more than 50% after treatment with either drug. Doxorubicin and docetaxel concordantly induced 251 genes predominantly involved in protein and macromolecule metabolism (upregulated), and cell cycle and DNA/RNA metabolism (downregulated). Doxorubicin treatment resulted in coregulation of a cluster of 345 probe sets involved in focal adhesion, Jak-Stat signaling pathway, cell adhesion molecules, and natural killer cell mediated cytotoxicity, whereas docetaxel treatment resulted in coregulation of a cluster of 448 probe sets involved in focal adhesion, neurodegenerative disorders, sphingolipid metabolism, and cell cycle. Tumors that were intrinsically sensitive or resistant to doxorubicin or docetaxel evoked distinct gene expression changes in response to the drug; doxorubicin-resistant tumors upregulated genes that were enriched for ErbB signaling, ubiquitin-mediated proteolysis, TGF-beta signaling, and MAP-kinase signaling pathways, whereas docetaxel-resistant tumors upregulated genes that were enriched for focal adhesion and regulation of actin cytoskeleton. The drug-specific tumor gene expression changes were validated in independent in-vitro and in-vivo datasets.

CONCLUSION

Gene expression alterations of breast cancer were specific to doxorubicin and docetaxel treatment, and yielded mechanistic insights into resistance to either drug. Gene expression analysis provides more global perspectives on resistance pathways that could be exploited for therapeutic selection.

The BAG-1 cochaperone is a negative regulator of p73-dependent transcription

High-level expression of Bcl-2 associated athanogene (BAG-1) protects cancer cells from stress-induced cell death and growth inhibition. These protective effects of BAG-1 are dependent on interactions with the HSC70 and HSP70 chaperones. However, the key stress-response molecules that are regulated by a BAG-1/chaperone mechanism have not been identified. In this study, we investigated the effects of BAG-1 overexpression on the function of p53 family proteins, p53, p63 and p73. Overexpression of BAG-1 isoforms interfered with the transactivating activity of p73 and p63, but had modest and variable effects on p53-dependent transcription. p73 and BAG-1 interacted in intact cells and overexpression of BAG-1 decreased the expression of p73. siRNA-mediated ablation of endogenous BAG-1 increased the activity of a p73-responsive promoter and this was reversed by knock-down of p73. The ability of BAG-1 to modulate p73 activity and expression, and to interact with p73 were dependent on amino acid residues required for the interaction of BAG-1 with HSC70 and HSP70. These results show that BAG-1 inhibits the transactivating functions of p73 and provide new insight into the mechanisms that control the expression of p73. Inhibition of p73 function may be one mechanism that contributes to the pro-survival activity of BAG-1.

Multiple, but concerted cellular activities of the human protein Hap46/BAG-1M and isoforms

The closely related human and murine proteins Hap46/BAG-1M and BAG-1, respectively, were discovered more than a decade ago by molecular cloning techniques. These and the larger isoform Hap50/BAG-1L, as well as shorter isoforms, have the ability to interact with a seemingly unlimited array of proteins of completely unrelated structures. This problem was partially resolved when it was realized that molecular chaperones of the hsp70 heat shock protein family are major primary association partners, binding being mediated by the carboxy terminal BAG-domain and the ATP-binding domain of hsp70 chaperones. The latter, in turn, can associate with an almost unlimited variety of proteins through their substrate-binding domains, so that ternary complexes may result. The protein folding activity of hsp70 chaperones is affected by interactions with Hap46/BAG-1M or isoforms. However, there also exist several proteins which bind to Hap46/BAG-1M and isoforms independent of hsp70 mediation. Moreover, Hap46/BAG-1M and Hap50/BAG-1L, but not the shorter isoforms, can bind to DNA in a sequence-independent manner by making use of positively charged regions close to their amino terminal ends. This is the molecular basis for their effects on transcription which are of major physiological relevance, as discussed here in terms of a model. The related proteins Hap50/BAG-1L and Hap46/BAG-1M may thus serve as molecular links between such diverse bioactivities as regulation of gene expression and protein quality control. These activities are coordinated and synergize in helping cells to cope with conditions of external stress. Moreover, they recently became markers for the aggressiveness of several cancer types.

Molecular profile of breast versus ovarian cancer cells in response to treatment with the anticancer drugs cisplatin, carboplatin, doxorubicin, etoposide and taxol

We assessed changes in the apoptosis-related genes BCL2, BAX, BCL2L12, FAS and CASPASE-3 in OVCAR-3 human ovarian cancer cells and BT-20 human breast cancer cells to provide an insight into the molecular mechanisms involved in the response of these cells to treatment with anticancer drugs and to assess their value as potential biomarkers of chemotherapy response in breast and ovarian cancer. Cells were treated with different chemotherapeutic drugs (cisplatin, carboplatin, doxorubicin, etoposide and taxol) and assessed for changes in the expression of apoptosis-related genes at the mRNA level. Total RNA was extracted, reverse-transcribed into cDNA and amplified by PCR using gene-specific primers. GAPDH was used as a housekeeping gene. Cytotoxicity was assessed by MTT assay. Both cancer cell lines responded differentially at the molecular level to the drug treatments. OVCAR-3 cells showed more pronounced sensitivity and changes compared to BT-20 cells at the mRNA level for different apoptosis-related genes, leading to cell and cancer type dependence in conjunction with drug dependence.

Expression patterns and prognostic value of Bag-1 and Bcl-2 in breast cancer

Introduction

Bcl-2 antanogene-1 (Bag-1) binds the anti-apoptotic mediator Bcl-2, and enhances its activity. Bcl-2 and Bag-1 are associated with chemotherapy resistance in cancer cells. Drugs that target Bcl-2 are currently in clinical development. The purpose of the present study was to examine expression patterns of Bag-1 in a large cohort of breast tumors and to assess the association with Bcl-2, estrogen receptor, progesterone receptor and Her2/neu, and other clinical/pathological variables.

Methods

Tissue microarrays containing primary specimens from 638 patients with 10-year follow-up were employed, and the expression of Bag-1, Bcl-2, estrogen receptor, progesterone receptor and Her2/neu was assessed using our automated quantitative analysis method. We used cytokeratin to define pixels as breast cancer (tumor mask) within the array spot, and we measured biomarker expression within the mask using Cy5 conjugated antibodies.

Results

High Bcl-2 expression was associated with improved survival in the entire cohort and in the node-positive subset (P = 0.008 and P = 0.002, respectively). High Bag-1 expression was associated with improved survival in the node-positive subset (P = 0.006). On multivariable analysis, neither Bcl-2 nor Bag-1 retained their independence as prognostic markers. Strong associations were found between Bag-1, Bcl-2, estrogen receptor and progesterone receptor.

Conclusion

Bag-1 and Bcl-2 expression in breast tumors is associated with improved outcome and steroid receptor positivity. Evaluation of Bcl-2 and Bag-1 expression in breast cancer may identify a subset of patients with a favorable prognosis, who might not benefit from chemotherapy or who might benefit from Bcl-2 targeting agents in addition to antihormonal therapy.

Prognostic value of Bcl-2 in breast cancer patients treated with neoadjuvant anthracycline based chemotherapy

We have analyzed the predictive/prognostic value of Bcl-2 protein in breast cancer patients treated with neoadjuvant chemotherapy. One hundred and ten patients were submitted to two different chemotherapeutic regimens: a) 5-fluorouracil, adriamycin or epirubicin, and cyclophosphamide (FAC/FEC) during 2-6 cycles before surgery and 3 or 4 additional cycles of FAC/FEC after surgery (n=40) and b) doxorubicin (D) 75 mg/m(2) or epirubicin (E) 120 mg/m(2) during 4 cycles before surgery, and 6 cycles of cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) after surgery (n=70). Bcl-2 expression, evaluated by immunohistochemistry, did not change significantly after chemotherapy and was not related to clinical/pathological response. In FAC/FEC group, Bcl-2 positive expression after chemotherapy correlated with better disease free survival (DFS) and overall survival (OS) (P=0.008 and P=0.001). In D/E group, Bcl-2 also correlated with better DFS and OS (P=0.03 and P=0.054) in the post-chemotherapy biopsies. An unusual nuclear localization of Bax was observed in some biopsies, but this localization did not correlate with the tumor response or outcome of the patients. We found that a high Bcl-2 expression had no predictive value but had prognostic value in breast cancer patients treated with neoadjuvant anthracycline based chemotherapy.

Clinical and pathological predictors of the response to neoadjuvant anthracycline chemotherapy in locally advanced breast cancer

PURPOSE

The aim of this study is to determine clinical and histopathological characteristics correlated to responsiveness to anthracycline-based neoadjuvant chemotherapy in breast cancer.

PATIENTS AND METHODS

We studied primary tumor specimens with local advanced breast cancer from 40 patients. Patients received anthracycline-based chemotherapy. Neoadjuvant regimen consisted in 600 mg/m2 5-fluorouracil, 60 mg/m2 doxorubicin, and 600 mg/m2 cyclophosphamide (FAC). The World Health Organization criteria were used to classify the tumors. We performed immunohistochemical staining for ER, PgR, HER-2, PCNA (proliferation cell nuclear antigen), Ki-67, p53, and Bcl-2. Clinical and histopathological characteristics were associated with clinical response and histopathological changes induced by chemotherapy.

RESULTS

The mean age was 47 +/- 14 yr. Twenty-three percent of patients were in stage IIB and 77% were in stages IIIA and IIIB. Seven percent of patients had progression of the disease. Stable disease was observed in 42% of patients and 45% had partial response. Only 7% of patients had a complete response. Factors associated with a better and major percentage of clinical response were the administration of doxorubicin-based chemotherapy, administration of more than three cycles, clinical N1, atypia, more than 10 mitosis per high-power field, moderate to severe SBR grade, and a major index of cellular proliferation.

CONCLUSION

We found that tumors with large volumes, N2 node status, low cellular proliferation rate, positive immunoreactivity to p53, and low differentiation grade have a lower response to neoadjuvant chemotherapy with anthracycline. These patients could benefit from a different chemotherapy scheme to obtain a better control and resection.

Application of Oligonucleotide Microarrays to Assess the Biological Effects of Neoadjuvant Imatinib Mesylate Treatment for Localized Prostate Cancer

PURPOSE

Neoadjuvant administration of antineoplastic therapies is used to rapidly assess the clinical and biological activity of novel systemic treatments. To assess the feasibility of using microarrays to assess molecular end points following targeted treatment in a heterogeneous tumor, we measured global gene expression in localized prostate cancer before and following neoadjuvant treatment with imatinib mesylate.

PATIENTS AND METHODS

Patients with intermediate-risk to high-risk prostate cancer were treated for 6 weeks with 200 to 300 mg of oral imatinib mesylate. Frozen tissue was obtained from pretreatment ultrasound-guided biopsies and posttreatment radical prostatectomy specimens. Oligonucleotide microarray analysis following laser capture microdissection (LCM) and RNA amplification was used to assess gene expression changes associated with imatinib mesylate therapy. Immunohistochemistry was used to measure protein expression of MKP1 and CD31 and to assess cellular apoptosis.

RESULTS

Of the 11 patients enrolled, high-quality microarray data was obtained from both biopsies (n = 7) and radical prostatectomy specimens (n = 9). Technically introduced intrasample gene expression variability was found to be significantly less than intertumor biological variability. Large gene expression differences were observed, and the gene with the most consistent differential expression (MKP1) was validated by immunohistochemistry. Gene set enrichment analysis suggests that imatinib mesylate therapy results in apoptosis of microvascular endothelial cells, an observation anecdotally supported by immunohistochemistry.

CONCLUSIONS

This study shows that high-quality microarray data can be generated using LCM and RNA amplification to discover potential mechanisms of targeted therapy in cancer.

In vivo model for research of breast cancer biomarkers

The preoperative (neoadjuvant) setting of breast cancer treatment is an optimal in vivo model by which to allow the characterization of biomarker expression pattern with the tumor remaining in situ throughout treatment as an in vivo measure of response to particular therapy. Elucidating surrogate molecular or cellular markers of tumor response to therapy, may provide biological insight into both, the mechanism of tumor growth dynamics and drug sensitivity/resistance. Owing to the knowledge that many drugs are effective on actively proliferating cells and more intriguingly, that many anticancer agents with differing modes of action achieve cytotoxic effects by inducing apoptosis, has lead to a reappraisal of traditional views of tumor response/resistance to cytotoxic drugs in vivo. Accordingly, this review article will focus on discussing apoptosis phenomena and the p53 and bcl-2 protein as its regulators of principal impor?tance; a cell proliferation determined by the Ki-67 expression, as the major counterbalancing process to apoptosis is also considered. This paper reviews the rationale for the use of these proteins as indices of tumor response to therapy, as well as the published literature regarding their clinical relevance. So far, no firm conclusions can be made concerning their predictive utility. .

Activities of the cochaperones Hap46/BAG-1M and Hap50/BAG-1L and isoforms

Since their discovery about a decade ago, human Hap46/BAG-1M, the larger isoform Hap50/BAG-1L, and related structures have caused quite some astonishment because of the seemingly unlimited array of possible interaction partners belonging to completely unrelated protein families. This problem was partially resolved when it was realized that molecular chaperones of the heat shock protein family Hsp70 are major primary association partners, which in turn, are able to bind a wide variety of unrelated protein structures, thus forming ternary complexes. Moreover, the protein folding activity of Hsp70 chaperones is affected; hence, the designation "cochaperones." Although many different proteins require mediation by Hsp70 chaperones for interactions with Hap50/BAG-1L, Hap46/BAG-1M, and isoforms, several other partner proteins are able to associate directly. In addition, Hap46/BAG-1M and Hap50/BAG-1L are also able to interact with DNA by making use of a positively charged region close to the amino terminal end of the polypeptide chain. This is the molecular basis for their effects on transcriptional activities, which are emphasized in this review and for which a molecular model is presented.

The Nuclear Transcription Factor κB/bcl-2 Pathway Correlates with Pathologic Complete Response to Doxorubicin-Based Neoadjuvant Chemotherapy in Human Breast Cancer

PURPOSE

Molecular factors involved in apoptosis may affect breast cancer response to chemotherapy. Herein, we studied the nuclear factor kappaB (NF-kappaB)/bcl-2 pathway to determine whether or not activation of this antiapoptotic pathway was associated with a poor response of human breast cancer to anthracycline-based neoadjuvant chemotherapy.

EXPERIMENTAL DESIGN

We studied 82 human breast cancer samples from patients treated with neoadjuvant doxorubicin-based chemotherapy and studied whether or not nuclear location of the transcription factor NF-kappaB was associated with expression of bcl-2 and bax and whether or not expression of these proteins correlated with chemotherapy response. Protein expression was measured with immunohistochemical staining. A dedicated breast cancer pathologist who was unaware of the clinical outcome data dichotomized the slides as positive or negative based on the presence or absence of cytoplasmic staining for bcl-2 and bax or nuclear staining for NF-kappaB.

RESULTS

Sixty-one percent of the tumors were positive for bcl-2, 85% were positive for bax, and 16% were positive for NF-kappaB. All bcl-2-positive tumors were also bax positive (P < 0.0001) and all NF-kappaB-positive tumors were both bcl-2 positive (P = 0.001) and bax positive (P = 0.113). Eleven of the 82 patients (13%) had a pathologic complete response (pCR) to chemotherapy. Patients with positive staining tumors for any of the markers less commonly achieved a pCR to chemotherapy than those with negative tumor staining. The pCR rates were NF-kappaB positive 0% (0 of 13) versus NF-kappaB negative 13% (11 of 69; P = 0.130); bcl-2 positive 4% (2 of 49) versus bcl-2 negative 27% (9 of 33; P = 0.004); and bax positive 6% (4 of 69) versus bax negative 58% (7 of 12; P < 0.001).

CONCLUSION

We conclude that nuclear localization of NF-kappaB correlates with bcl-2 and bax expression and that the NF-kappaB/bcl-2 pathway may be associated with a poor response to neoadjuvant doxorubicin-based chemotherapy.

Response rate of fibrosarcoma cells to cytotoxic drugs on the expression level correlates to the therapeutic response rate of fibrosarcomas and is mediated by regulation of apoptotic pathways

BACKGROUND

Because of the high resistance rate of fibrosarcomas against cytotoxic agents clinical chemotherapy of these tumors is not established. A better understanding of the diverse modes of tumor cell death following cytotoxic therapies will provide a molecular basis for new chemotherapeutic strategies. In this study we elucidated the response of a fibrosarcoma cell line to clinically used cytostatic agents on the level of gene expression.

METHODS

HT1080 fibrosarcoma cells were exposed to the chemotherapeutic agents doxorubicin, actinomycin D or vincristine. Total RNA was isolated and the gene expression patterns were analyzed by microarray analysis. Expression levels for 46 selected candidate genes were validated by quantitative real-time PCR.

RESULTS

The analysis of the microarray data resulted in 3.309 (actinomycin D), 1.019 (doxorubicin) and 134 (vincristine) probesets that showed significant expression changes. For the RNA synthesis blocker actinomycin D, 99.4% of all differentially expressed probesets were under-represented. In comparison, probesets down-regulated by doxorubicin comprised only 37.4% of all genes effected by this agent. Closer analysis of the differentially regulated genes revealed that doxorubicin induced cell death of HT1080 fibrosarcoma cells mainly by regulating the abundance of factors mediating the mitochondrial (intrinsic) apoptosis pathway. Furthermore doxorubicin influences other pathways and crosstalk to other pathways (including to the death receptor pathway) at multiple levels. We found increased levels of cytochrome c, APAF-1 and members of the STAT-family (STAT1, STAT3), while Bcl-2 expression was decreased. Caspase-1, -3, -6, -8, and -9 were increased indicating that these proteases are key factors in the execution of doxorubicin mediated apoptosis.

CONCLUSION

This study demonstrates that chemotherapy regulates the expression of apoptosis-related factors in fibrosarcoma cells. The number and the specific pattern of the genes depend on the used cytotoxic drug. The response rates on the gene expression level, i.e. the number of genes regulated by the drugs actinomycin D, doxorubicin and vincristine, correlate to the clinical effectiveness of the drugs. Doxorubicin seems to exert its cytotoxic mechanism by regulating genes, which are involved in several different apoptosis regulating pathways. The exact knowledge of the genes affected by the drugs will help to understand the diverse modes of soft tissue sarcoma cell death in response to cytotoxic therapies.

Prognostic molecular markers in early breast cancer

A multitude of molecules involved in breast cancer biology have been studied as potential prognostic markers. In the present review we discuss the role of established molecular markers, as well as potential applications of emerging new technologies. Those molecules used routinely to make treatment decisions in patients with early-stage breast cancer include markers of proliferation (e.g. Ki-67), hormone receptors, and the human epidermal growth factor receptor 2. Tumor markers shown to have prognostic value but not used routinely include cyclin D1 and cyclin E, urokinase-like plasminogen activator/plasminogen activator inhibitor, and cathepsin D. The level of evidence for other molecular markers is lower, in part because most studies were retrospective and not adequately powered, making their findings unsuitable for choosing treatments for individual patients. Gene microarrays have been successfully used to classify breast cancers into subtypes with specific gene expression profiles and to evaluate prognosis. RT-PCR has also been used to evaluate expression of multiple genes in archival tissue. Proteomics technologies are in development.