Neoadjuvant endocrine therapy for breast cancer: past, present and future

Alterations in estrogen signalling pathways upon acquisition of anthracycline resistance in breast tumor cells

Intrinsic or acquired drug resistance is a major impediment to the successful treatment of women with breast cancer using chemotherapy. We have observed that MCF-7 breast tumor cells selected for resistance to doxorubicin or epirubicin (MCF-7_DOX2 and MCF-7_EPI cells, respectively) exhibited increased expression of several members of the aldo-keto reductase (AKR) gene family (in particular AKR1C3 and AKR1B10) relative to control MCF-7_CC cells selected by propagation in the absence of drug. Normal cellular roles for the AKRs include the promotion of estrogen (E2) synthesis from estrone (E1) and the hydroxylation and detoxification of exogenous xenobiotics such as anthracycline chemotherapy drugs. While hydroxylation of anthracyclines strongly attenuates their cytotoxicity, it is unclear whether the enhanced AKR expression in the above anthracycline-resistant cells promotes E2 synthesis and/or alterations in E2 signalling pathways and whether such changes contribute to enhanced survival and anthracycline resistance. To determine the role of AKRs and E2 pathways in doxorubicin resistance, we examined changes in the expression of E2-related genes and proteins upon acquisition of doxorubicin resistance. We also assessed the effects of AKR overexpression or downregulation or the effects of activators or inhibitors of E2-dependent pathways on previously acquired resistance to doxorubicin. In this study we observed that the enhanced AKR expression upon acquisition of anthracycline resistance was, in fact, associated with enhanced E2 production. However, the expression of estrogen receptor α (ERα) was reduced by 2- to 5-fold at the gene transcript level and 2- to 20-fold at the protein level upon acquisition of anthracycline resistance. This was accompanied by an even stronger reduction in ERα phosphorylation and activity, including highly suppressed expression of two proteins under E2-dependent control (Bcl-2 and cyclin D1). The diminished Bcl-2 and cyclin D1 expression would be expected to reduce the growth rate of the cells, a hypothesis which was confirmed in subsequent cell proliferation experiments. AKR1C3 or AKR1B10 overexpression alone had no effect on doxorubicin sensitivity in MCF-7_CC cells, while siRNA-mediated knockdown of AKR1C3 and/or AKR1B10 expression had no significant effect on sensitivity to doxorubicin in MCF-7_DOX2 or MCF-7_EPI cells. This suggested that enhanced or reduced AKR expression/activity is insufficient to confer anthracycline resistance or sensitivity to breast tumor cells, respectively. Rather, it would appear that AKR overexpression acts in concert with other proteins to confer anthracycline resistance, including reduced E2-dependent expression of both an important apoptosis inhibitor (Bcl-2) and a key protein associated with activation of cell cycle-dependent kinases (cyclin D1).

Optimal combination of radiotherapy and endocrine drugs in breast cancer treatment

PURPOSE

Breast cancer is the most common cancer in women. Radiotherapy is considered a standard treatment option after surgery and adjuvant endocrine therapy is also universally used. Tamoxifen and letrozole are the current first-line endocrine therapy drugs. However, information has been scarce about how best to sequence these therapies to maximize their effectiveness and keep toxic effects to a minimum. In this study, we observed the effect of different sequence combination of radiotherapy and endocrine drugs, tamoxifen or letrozole, to get the best treatment sequence.

MATERIALS AND METHODS

The combination effect of radiotherapy and tamoxifen was observed on breast tumour cell line MCF-7, radiotherapy and letrozole on aromatase-expressing breast tumour cell line MCF-7CA. Irradiation was performed with 6Gy, except for doses ranging from 0 to 8Gy for clone formation assay. Tamoxifen or letrozole was added before or after irradiation, respectively. Radiosensitivity was evaluated by clonogenic assay, cell viability by 3-(4,-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) assay. To explore the potential mechanism, cell apoptosis was determined by DNA-binding dye 4',6-diamidino-2-phenylindole dihydrochloride (DAPI) assay, the change of Bcl-2 and Bax expression was by western blot.

RESULTS

Although no significant statistical difference was observed between different sequence, tamoxifen and letrozole both increased radiosensitivity. Furthermore, the above inhibitory effect was related with apoptosis signaling pathway, especially Bcl-2 and Bax.

CONCLUSION

Taken together, these results suggested that endocrine drugs, such as tamoxifen and letrozole, have potential application with radiotherapy.

FOXM1 (Forkhead box M1) in tumorigenesis: overexpression in human cancer, implication in tumorigenesis, oncogenic functions, tumor-suppressive properties, and target of anticancer therapy

FOXM1 (Forkhead box M1) is a typical proliferation-associated transcription factor and is also intimately involved in tumorigenesis. FOXM1 stimulates cell proliferation and cell cycle progression by promoting the entry into S-phase and M-phase. Additionally, FOXM1 is required for proper execution of mitosis. In accordance with its role in stimulation of cell proliferation, FOXM1 exhibits a proliferation-specific expression pattern and its expression is regulated by proliferation and anti-proliferation signals as well as by proto-oncoproteins and tumor suppressors. Since these factors are often mutated, overexpressed, or lost in human cancer, the normal control of the foxm1 expression by them provides the basis for deregulated FOXM1 expression in tumors. Accordingly, FOXM1 is overexpressed in many types of human cancer. FOXM1 is intimately involved in tumorigenesis, because it contributes to oncogenic transformation and participates in tumor initiation, growth, and progression, including positive effects on angiogenesis, migration, invasion, epithelial-mesenchymal transition, metastasis, recruitment of tumor-associated macrophages, tumor-associated lung inflammation, self-renewal capacity of cancer cells, prevention of premature cellular senescence, and chemotherapeutic drug resistance. However, in the context of urethane-induced lung tumorigenesis, FOXM1 has an unexpected tumor suppressor role in endothelial cells because it limits pulmonary inflammation and canonical Wnt signaling in epithelial lung cells, thereby restricting carcinogenesis. Accordingly, FOXM1 plays a role in homologous recombination repair of DNA double-strand breaks and maintenance of genomic stability, that is, prevention of polyploidy and aneuploidy. The implication of FOXM1 in tumorigenesis makes it an attractive target for anticancer therapy, and several antitumor drugs have been reported to decrease FOXM1 expression.

Chemotherapy (CT) and hormonotherapy (HT) as neoadjuvant treatment in luminal breast cancer patients: results from the GEICAM/2006-03, a multicenter, randomized, phase-II study

BACKGROUND

Luminal breast cancer is a highly endocrine responsive disease. However, the therapeutic benefit of chemotherapy (CT) in this population is not fully characterized. This study investigates the value of CT and hormone therapy (HT) in luminal breast cancer patients in the neoadjuvant setting.

PATIENTS AND METHODS

Patients with operable breast cancer and immunophenotypically defined luminal disease (ER+/PR+/HER2-/cytokeratin 8/18+) were recruited. Patients were randomized to CT (epirubicin 90 mg/m(2) plus cyclophosphamide 600 mg/m(2) 4 cycles followed by docetaxel 100 mg/m(2 )4 cycles [EC-T]) or HT (exemestane 25 mg daily 24 weeks [combined with goserelin in premenopausal patients]). The primary end point was the clinical response measured by magnetic resonance imaging.

RESULTS

Ninety-five patients were randomized (47 CT, 48 HT). The clinical response rate was 66% for CT and 48% for HT (P = 0.075). We performed an unplanned analysis based on Ki67 levels (cut-off of 10%). Similar clinical response was seen between arms in patients with low Ki67 (CT: 63%, HT: 58%; P = 0.74); patients with high Ki67 had a better response with CT (67 versus 42%; P = 0.075). Grade 3/4 toxicity was more frequent with CT.

CONCLUSIONS

Luminal immunophenotype is not enough to identify patients who do not benefit from neoadjuvant CT. Luminal patients with low proliferation index could potentially avoid CT.

Pathologic changes in breast cancer after anti-estrogen therapy

Breast cancer patients do not commonly receive anti-estrogens prior to surgical excision. We reviewed a cohort of patients who received preoperative anti-estrogen therapy after baseline biopsy and then had a repeat biopsy after several weeks on treatment. Patients with estrogen receptor positive tumors received anastrozole and fulvestrant in combination with gefitinib. Core needle biopsies were performed at day 1 and 21, and tumors were completely excised if operable at day 112. All patients were postmenopausal. Following treatment, tumors had degenerative changes including smudged nuclei, decreased nuclear size, intranuclear vacuoles, vacuolated cytoplasm, and increased cellular discohesion. In addition, increased tubule formation and intracytoplasmic lumina were seen in 6/9 cases (66.7%) and decreased mitotic rate was demonstrated in 7/9 cases (77.8%). These findings indicate increased differentiation of the tumor cells in response to anti-estrogen therapy and that may correlate with clinical response.

Modern approach to metabolic rehabilitation of cancer patients: biguanides (phenformin and metformin) and beyond

Comparing the experience accumulated for more than 40 years in the Laboratory of Endocrinology of Petrov Institute of Oncology (St Petersburg, Russia) with similar approaches practiced elsewhere, evidence supports the reasonability of metabolic rehabilitation of patients suffering from breast cancer or other hormone-dependent malignancies. The primary objective of such approaches is to improve treatment results by ameliorating hormonal-metabolic disturbances, including excess body fat, glucose intolerance, insulin resistance and manifestations of endocrine-genotoxic switchings, and modify tissue and cellular targets or mechanisms related or nondirectly related to the aforementioned disturbances. The relevant measures may be categorized as pharmacological (antidiabetic biguanides exemplified with metformin being most popular but not exclusive) and nonpharmacological (rational nutrition, moderate physical activity and so forth) and used separately or in different combinations.

Pilot trial of preoperative (neoadjuvant) letrozole in combination with bevacizumab in postmenopausal women with newly diagnosed estrogen receptor- or progesterone receptor-positive breast cancer

INTRODUCTION

Tumor content or expression of vascular endothelial growth factor (VEGF) is associated with impaired efficacy of antiestrogen adjuvant therapy. We designed a pilot study to assess the feasibility and short-term efficacy of neoadjuvant letrozole and bevacizumab (anti-VEGF) in postmenopausal women with stage II and III estrogen receptor/progesterone receptor-positive breast cancer.

PATIENTS AND METHODS

Patients were treated with a neoadjuvant regimen of letrozole orally 2.5 mg/day and bevacizumab intravenously 15 mg/kg every 3 weeks for a total of 24 weeks before the surgical treatment of their breast cancer. Patients were followed for toxicity at 3-week intervals, and tumor assessment (a physical examination and ultrasound) was performed at 6-week intervals. Positron emission tomography (PET) scans were performed before therapy and 6 weeks after the initiation of therapy.

RESULTS

Twenty-five evaluable patients were treated. The regimen was well-tolerated, except in 2 patients who were taken off the study for difficulties controlling their hypertension. An objective clinical response occurred in 17 of 25 patients (68%), including 16% complete responses (CRs) and 52% partial responses. The 4 patients with clinical CRs manifested pathologic CRs in their breasts (16%), although 1 patient had residual tumor cells in her axillary nodes. Eight of 25 patients (32%) attained stage 0 or 1 status. The PET scan response at 6 weeks correlated with clinical CRs and breast pathologic CRs at 24 weeks (P < .0036).

CONCLUSION

Combination neoadjuvant therapy with letrozole and bevacizumab was well-tolerated and resulted in impressive clinical and pathologic responses. The Translational Breast Cancer Research Consortium has an ongoing randomized phase II trial of this regimen in this patient population.

DEAD box 1: a novel and independent prognostic marker for early recurrence in breast cancer

Breast cancer is a heterogeneous disease characterized by diverse molecular signatures and a variable response to therapy. Clinical management of breast cancer is guided by the expression of estrogen and progesterone receptors and HER2 amplification. New prognostic and predictive markers, as well as additional targets for therapy, are needed for more effective management of this disease. Gene expression microarrays were probed with RNAs from 176 primary breast cancer samples and tissue microarrays immunostained with anti-DDX1 antibody, an antibody to DEAD box protein DDX1, a putative RNA-RNA and RNA-DNA unwinding protein normally found in the nucleus. Half of the patient cohort had experienced early relapse despite standard adjuvant therapy, but were otherwise matched for estrogen receptor and HER2 status, stage and duration of follow-up. Here, we identify DDX1 RNA overexpression as an independent prognostic marker for early recurrence in primary breast cancer, with a hazard ratio of 4.31 based on logrank analysis of Kaplan-Meier curves. Elevated levels of DDX1 protein in the cytoplasm also independently correlate with early recurrence with a hazard ratio of 1.90. In conclusion, our data indicate a strong and independent association between poor prognosis and deregulation of the DEAD box protein DDX1. We propose that elevated levels of DDX1 RNA or the presence of DDX1 in the cytoplasm could serve as an effective prognostic biomarker for early recurrence in primary breast cancer.

Studies on tamoxifen encapsulated in lipid vesicles: effect on the growth of human breast cancer MCF-7 cells

Tamoxifen is a nonsteroidal estrogen-receptor modulator widely used in the treatment of breast cancer. Apoptosis has been reported to be a major mechanism for its antitumor effect. In the current studies, an endeavor was made to investigate the efficacy of vesicularly encapsulated tamoxifen on human breast cancer MCF-7 cells. Phospholipid-based vesicular systems viz. conventional liposomes and elastic-membrane liposomes were employed to encapsulate the drug. The MTT colorimetric assay was used to determine the efficacy of the tested formulations. The results demonstrated composition-dependent strong inhibition in the viability of MCF-7 cells with encapsulated tamoxifen vis-à-vis free drug. The encouraging findings from the current work construe immense potential of the lipid-based vesicular systems in the treatment of breast cancer.