Anthracycline resistance in breast cancer: clinical applications of current knowledge

Initial Identification of UDP-Glucose Dehydrogenase as a Prognostic Marker in Breast Cancer Patients, Which Facilitates Epirubicin Resistance and Regulates Hyaluronan Synthesis in MDA-MB-231 Cells

UDP-glucose-dehydrogenase (UGDH) synthesizes UDP-glucuronic acid. It is involved in epirubicin detoxification and hyaluronan synthesis. This work aimed to evaluate the effect of UGDH knockdown on epirubicin response and hyaluronan metabolism in MDA-MB-231 breast cancer cells. Additionally, the aim was to determine UGDH as a possible prognosis marker in breast cancer. We studied UGDH expression in tumors and adjacent tissue from breast cancer patients. The prognostic value of UGDH was studied using a public Kaplan–Meier plotter. MDA-MB-231 cells were knocked-down for UGDH and treated with epirubicin. Epirubicin-accumulation and apoptosis were analyzed by flow cytometry. Hyaluronan-coated matrix and metabolism were determined. Autophagic-LC3-II was studied by Western blot and confocal microscopy. Epirubicin accumulation increased and apoptosis decreased during UGDH knockdown. Hyaluronan-coated matrix increased and a positive modulation of autophagy was detected. Higher levels of UGDH were correlated with worse prognosis in triple-negative breast cancer patients that received chemotherapy. High expression of UGDH was found in tumoral tissue from HER2^--patients. However, UGDH knockdown contributes to epirubicin resistance, which might be associated with increases in the expression, deposition and catabolism of hyaluronan. The results obtained allowed us to propose UGDH as a new prognostic marker in breast cancer, positively associated with development of epirubicin resistance and modulation of extracellular matrix.

Epigenetic regulation of ZEB1-RAB25/ESRP1 axis plays a critical role in phenylbutyrate treatment-resistant breast cancer

Phenylbutyrate (PB) is a histone deacetylase antagonist that also exhibits antitumor activity. In this study, we used 7 breast cancer cell lines to identify biomarker candidates that predict PB sensitivity in breast cancer.

Comprehensive gene expression profiles were compared using microarrays, and the importance of the identified genes to PB sensitivity was confirmed in gene transfection experiments. CRL and MDAMB453 cells were identified as PB-sensitive, while MDAMB231 cells were PB-resistant.RAB25 and ESRP1 were identified as key regulators of PB sensitivity, while ANKD1, ETS1, PTRF, IFI16 and KIAA1199 acted as PB resistance-related genes. Expression of these genes was dramatically altered by DNA demethylation treatments. RAB25 expression inhibited IFI16 and PTRF, while ESRP1 expression suppressed ANKRD1, ETS1, and KIAA1199. Both RAB25 and ESRP1 were suppressed by ZEB1, which was in turn regulated via epigenetic mechanisms. Thus, PB sensitivity is influenced by epigenetic expression alteration of ZEB1. The genes associated with PB sensitivity are downstream targets of ZEB1. Epigenetic regulation of ZEB1 may prove valuable as a critical biomarker for predicting resistance to breast cancer therapies.

Use of ribozymes and antisense oligodeoxynucleotides to investigate mechanisms of drug resistance

Chemotherapy can cure a number of human cancers but resistance (either intrinsic or acquired) remains a significant problem in many patients and in many types of solid tumour. Combination chemotherapy (using drugs with different cellular targets/mechanisms) was introduced in order to kill cells which had developed resistance to a specific drug, and to allow delivery of a greater total dose of anti-cancer chemicals by combining drugs with different side-effects (Pratt et al., 1994). Nearly all anti-cancer drugs kill tumour cells by activating an endogenous bio-chemical pathway for cell suicide, known as programmed cell death or apoptosis.

A serum protein profile predictive of the resistance to neoadjuvant chemotherapy in advanced breast cancers

Prediction of the responses to neoadjuvant chemotherapy (NACT) can improve the treatment of patients with advanced breast cancer. Genes and proteins predictive of chemoresistance have been extensively studied in breast cancer tissues. However, noninvasive serum biomarkers capable of such prediction have been rarely exploited. Here, we performed profiling of N-glycosylated proteins in serum from fifteen advanced breast cancer patients (ten patients sensitive to and five patients resistant to NACT) to discover serum biomarkers of chemoresistance using a label-free liquid chromatography-tandem MS method. By performing a series of statistical analyses of the proteomic data, we selected thirteen biomarker candidates and tested their differential serum levels by Western blotting in 13 independent samples (eight patients sensitive to and five patients resistant to NACT). Among the candidates, we then selected the final set of six potential serum biomarkers (AHSG, APOB, C3, C9, CP, and ORM1) whose differential expression was confirmed in the independent samples. Finally, we demonstrated that a multivariate classification model using the six proteins could predict responses to NACT and further predict relapse-free survival of patients. In summary, global N-glycoproteome profile in serum revealed a protein pattern predictive of the responses to NACT, which can be further validated in large clinical studies.

Discordant influence of amphotericin B on epirubicin cytotoxicity in primary hepatic malignant cells collected by a new primary culture technique

BACKGROUND

The purpose of this prospective study was to investigate whether amphotericin B (AmB) had any potential role in the systemic chemotherapy of primary hepatic malignancy using cancer cells collected by the authors' method of primary culture.

METHODS

The specimens obtained by ultrasound-guided fine-needle aspiration biopsy (22 G) from 15 patients with hepatocellular carcinoma (HCC) and one with cholangiocarcinoma were plated into culture flask without disaggregation by trypsin-ethylenediamine tetra-acetic acid solution. Six patients with HCC and one patient with cholangiocarcinoma (7/16, 44%) had successful culture and the cancer cells at the 4th passage were continuously exposed to therapeutic ranges of epirubicin (0, 0.5, 1.0, 1.5, 2.0 microg/mL) with or without the combination of 2.5 microg/mL AmB for 24 h. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was applied to evaluate the effects of the drugs. A human HCC cell line (HA 22T/VGH) was studied for comparison.

RESULTS

Addition of AmB showed no influence on epirubicin cytotoxicity in two patients (one partial resistant HCC and one epirubicin-sensitive cholangiocarcinoma; 25%), augmentation of the epirubicin cytotoxicity in two patients (one total resistant HCC, partial resistant HA 22T/VGH cell line and one epirubicin-sensitive HCC; 37.5%), and decrease of epirubicin cytotoxicity in the remaining three (one partial resistant and two epirubicin-sensitive HCC; 37.5%).

CONCLUSIONS

Amphotericin B has a discordant influence on epirubicin cytotoxicity in primary cultured hepatic malignant cells. Application of AmB in the systemic chemotherapy of primary hepatic malignancy should be limited to patients with positive AmB effect evaluated by an in vitro sensitivity test such as the present method.

Neoadjuvant Chemotherapy of Breast Cancer

The use of neoadjuvant chemotherapy in the treatment of breast cancer has been evolving during the past two decades. Fisher's group accomplished the scientific rationale in mouse models in the 1970s. The Milan group was the first to use neoadjuvant therapy in locally advanced breast cancer and also determined that adjuvant sequential doxorubicin with cyclophosphamide/methotrexate/fluorouracil (CMF) offered improved survival when compared to alternating CMF with doxorubicin. Other groups (M. D. Anderson and NSABP) have evaluated similar doxorubicin-based neoadjuvant therapies in locally advanced breast cancer (LABC) and in early disease. These studies have shown an increase in breast-conserving therapy (BCT) and an increase in pathologic complete response (pCR) when neoadjuvant therapy was used. Due to anthracycline resistance, taxanes were added to the doxorubicin-based neoadjuvant chemotherapy regimen with an increase in BCT and pCR than when an anthracycline regimen was used alone. Overall survival has yet to be determined when comparing an anthracycline-based regimen to the same regimen with the addition of a sequential taxane. Therefore, a combined treatment of an anthracycline/cyclophosphamide/taxane regimen is the recommended neoadjuvant chemotherapy for patients with breast cancer.

Neoadjuvant docetaxel in locally advanced breast cancer

Neoadjuvant chemotherapy produces substantial increases in clinical response rates and rates of breast conserving therapy. Pathologic response rate, though generally low, is an important outcome as it is presumably associated with eradication of micrometastatic disease and may likely result in improved outcomes. Anthracyclines have long been considered the most efficacious chemotherapy agents for neoadjuvant therapy of early breast cancer. Unfortunately, not all patients respond to neoadjuvant anthracycline-based chemotherapy. In an effort to improve primary tumor response, docetaxel, an active agent in breast cancer, has been evaluated in the neoadjuvant setting. Several randomized trials, including the NSABP B-27, GEPAR-duo, and the Aberdeen trial, evaluating docetaxel in sequence with a doxorubicin-based neoadjuvant regimen have been reported, with encouraging findings. We designed the Aberdeen trial with two primary aims: (1) to evaluate primary docetaxel in patients that initially fail a neoadjuvant anthracycline-based polychemotherapy regimen, and (2) to compare a docetaxel-based neoadjuvant regimen with a standard anthracycline-based regimen in patients who do respond to the first four cycles of the anthracycline-based regimen. Eligible patients (n = 162) had previously untreated large (> or = 3 cm) or locally advanced (T3, T4, T x N2) breast cancer. All received four cycles of CVAP, after which clinical response was assessed. Responding patients were then randomized to four additional cycles of CVAP or to docetaxel 100 mg/m2 every 3 weeks for four cycles. Patients failing to respond to CVAP received the docetaxel regimen. After the first four cycles of CVAP, the overall response rate (ORR) was 67%. Ultimately, responses were higher in the group randomized to docetaxel compared with those continuing CVAP (cCR: 94% vs. 66%; p = 0.001; pCR 34% vs. 16%; p = 0.04). The addition of docetaxel improved overall survival and disease-free survival for patients responding to four cycles of CVAP as compared with those receiving eight cycles of CVAP. Relative dose intensity was higher and the incidence of severe leukopenia was lower in the group randomized to docetaxel. These data and data from the NSABP B-27 and GEPAR-duo trials strongly support a combined anthracycline/docetaxel regimen in the neoadjuvant setting.

Neoadjuvant chemotherapy in breast cancer: significantly enhanced response with docetaxel

PURPOSE

To compare the efficacy of neoadjuvant (NA) docetaxel (DOC) with anthracycline-based therapy and determine the efficacy of NA DOC in patients with breast cancer initially failing to respond to anthracycline-based NA chemotherapy (CT).

PATIENTS AND METHODS

Patients with large or locally advanced breast cancer received four pulses of cyclophosphamide 1,000 mg/m(2), doxorubicin 50 mg/m(2), vincristine 1.5 mg/m(2), and prednisolone 40 mg (4 x CVAP) for 5 days. Clinical tumor response was assessed. Those who responded (complete response [CR] or partial response [PR]) were randomized to receive further 4 x CVAP or 4 x DOC (100 mg/m(2)). All nonresponders received 4 x DOC.

RESULTS

One hundred sixty-two patients were enrolled; 145 patients completed eight cycles of NA CT. One hundred two patients (66%) achieved a clinical response (PR or CR) after 4 x CVAP. After randomization, 50 patients received 4 x CVAP and 47 patients received 4 x DOC. In patients who received eight cycles of CT, the clinical CR (cCR) and clinical PR (cPR) (94% v 66%) and pathologic CR (pCR) (34% v 16%) response rates were higher (P =.001 and P =.04) in those who received further DOC. Intention-to-treat analysis demonstrated cCR and cPR (85% v 64%; P =.03) and pCR (31% v 15%; P =.06). Axillary lymph node examination revealed residual tumor in 33% of patients who received 8 x CVAP and 38% of patients who received further DOC. In patients who failed to respond to the initial CVAP, 4 x DOC resulted in a cCR and cPR rate of 55% and a pCR rate of 2%. Forty-four percent of these patients had residual tumor within axillary lymph nodes.

CONCLUSION

NA DOC resulted in substantial improvement in responses to DOC.

Y-box factor YB-1 predicts drug resistance and patient outcome in breast cancer independent of clinically relevant tumor biologic factors HER2, uPA and PAI-1

Intrinsic or acquired resistance to chemotherapy is responsible for failure of current treatment regimens in breast cancer patients. The Y-box protein YB-1 regulates expression of the P-glycoprotein gene mdr1, which plays a major role in the development of a multidrug-resistant tumor phenotype. In human breast cancer, overexpression and nuclear localization of YB-1 is associated with upregulation of P-glycoprotein. In our pilot study, we analyzed the clinical relevance of YB-1 expression in breast cancer (n = 83) after a median follow-up of 61 months and compared it with tumor-biologic factors already used for clinical risk-group discrimination, i.e., HER2, urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1). High YB-1 expression in tumor tissue and surrounding benign breast epithelial cells was significantly associated with poor patient outcome. In patients who received postoperative chemotherapy, the 5-year relapse rate was 66% in patients with high YB-1 expression. In contrast, in patients with low YB-1 expressions, no relapse has been observed so far. YB-1 expression thus indicates clinical drug resistance in breast cancer. Moreover, YB-1 correlates with breast cancer aggressiveness: in patients not treated with postoperative chemotherapy, those with low YB-1 expression are still free of disease, whereas the 5-year relapse rate in those with high YB-1 was 30%. There was no significant correlation between YB-1 expression and either HER2 expression or uPA and PAI-1 levels. Risk-group assessment achieved by YB-1 differed significantly from that by HER2 or uPA/PAI-1. In conclusion, YB-1 demonstrated prognostic and predictive significance in breast cancer by identifying high-risk patients in both the presence and absence of postoperative chemotherapy, independent of tumor-biologic factors currently available for clinical decision making.

Epirubicin: a review of its efficacy as adjuvant therapy and in the treatment of metastatic disease in breast cancer

Epirubicin is a semisynthetic derivative of doxorubicin which has been extensively evaluated in patients with breast cancer. It is effective in the management of metastatic disease and as adjuvant therapy in patients with early breast cancer. In the adjuvant setting, epirubicin-based therapy appears to have efficacy at least equivalent to that of the standard therapy cyclophosphamide, methotrexate and fluorouracil (CMF), with the most recent trials, predominantly in premenopausal patients, reporting significant gains in relapse-free survival and overall survival for epirubicin-based vs CMF therapy. In a single trial, the 5-year relapse-free survival of postmenopausal patients receiving long term hormonal therapy (tamoxifen) was significantly increased when epirubicin was added as single-agent chemotherapy and compared with tamoxifen alone. In patients with metastatic disease, epirubicin- and doxorubicin-containing regimens (with cyclophosphamide and fluorouracil; FEC and FAC) are therapeutically equivalent. Increasing the dose of epirubicin appears to improve response rates in patients with either metastatic or early disease but, with the exception of 1 adjuvant study, improved overall survival has not been demonstrated. Quality of life (QOL) has yet to be adequately evaluated with epirubicin. The major adverse effects of epirubicin are acute dose-limiting haematotoxicity and cumulative dose-related cardiotoxicity. Other important adverse effects include mucositis, nausea and vomiting, reversible alopecia and local cutaneous reactions. However, the tolerability of epirubicin is better than that of doxorubicin at equimolar doses.

CONCLUSION

Epirubicin has been extensively investigated in patients with breast cancer and has been found to be a highly effective agent, both for the treatment of patients with metastatic disease and as an adjuvant therapy. Recent trials have confirmed that, in selected patients requiring adjuvant therapy, FEC therapy is at least as effective as CMF, a standard treatment. FEC is also therapeutically equivalent to FAC in patients with metastatic breast cancer, and because the therapeutic index appears to be better the opportunity exists to increase dose intensity in an effort to improve efficacy. Such trials, and those of combinations of epirubicin with newer or alternative agents, should result in the introduction of more effective and better tolerated epirubicin-based protocols for adjuvant therapy and the management of patients with advanced breast cancer. In the meantime there is sufficient evidence to justify consideration of epirubicin for inclusion in first-line therapies for patients with early or metastatic breast cancer.

Glutathione S-transferases in wild-type and doxorubicin-resistant MCF-7 human breast cancer cell lines

1. Overexpression of glutathione S-transferases (GST) in breast cancer cells is hypothesized to be a component of the multifactorial doxorubicin-resistant phenotype. 2. We have characterized the expression of GST enzymes at the catalytic activity, protein and mRNA levels in wild-type MCF-7 (MCF-7/WT) human breast cancer cells and a line selected for resistance to doxorubicin (MCF-7/ADR), with the goal of modulating GST activity to overcome resistance. 3. The MCF-7/ADR cells were 30-65-fold more resistant to doxorubicin than the MCF-7/WT cells. 4. Total cytosolic GST catalytic activity was elevated 23-fold in the MCF-7/ADR cells as compared with the MCF-7/WT cells, and the MCF-7/ADR cells also showed 3-fold increases in catalytic activity toward GST mu and alpha class-selective substrates. Neither cell line showed detectable catalytic activity with a GST mu class-selective substrate. 5. MCF-7/ADR cells showed pronounced overexpression of GST mu protein and GST P1 mRNA in comparison with the wild-type cell line. Neither cell line displayed detectable GST alpha or mu at the protein level. 6. A glutathione analogue that functions as a selective GST alpha inhibitor was more potent at inhibiting total cytosolic GST catalytic activity in the MCF-7/ADR cell line than GST alpha and mu class-selective inhibitory glutathione analogues and the non-selective GST inhibitor ethacrynic acid. 7. The multidrug resistance-associated protein, which can function as a glutathione-conjugate transporter, appeared weakly overexpressed in the MCF-7/ADR cells in comparison with the MCF-7/WT cells.