Naruto Taira

The estrogen receptor influences microtubule-associated protein tau (MAPT) expression and the selective estrogen receptor inhibitor fulvestrant downregulates MAPT and increases the sensitivity to taxane in breast cancer cells

IntroductionMicrotubule-associated protein tau (MAPT) inhibits the function of taxanes and high expression of MAPT decreases the sensitivity to taxanes. The relationship between estrogen receptor (ER) and MAPT in breast cancer is unclear. In this study, we examined the correlation of MAPT expression with the sensitivity of human breast cancer cells to taxanes, and the relationship between ER and MAPT.MethodsThe correlation between MAPT expression and sensitivity to taxanes was investigated in 12 human breast cancer cell lines. Alterations in cellular sensitivity to taxanes were evaluated after knockdown of MAPT expression. ER expression was knocked down or stimulated in MAPT- and ER-positive cell lines to examine the relationship between ER and MAPT. The cells were also treated with hormone drugs (tamoxifen and fulvestrant) and taxanes.ResultsmRNA expression of MAPT did not correlate with sensitivity to taxanes. However, expression of MAPT protein isoforms of less than 70 kDa was correlated with a low sensitivity to taxanes. Downregulation of MAPT increased cellular sensitivity to taxanes. MAPT protein expression was increased by stimulation with 17-β-estradiol or tamoxifen, but decreased by ER downregulation and by fulvestrant, an ER inhibitor. The combination of fulvestrant with taxanes had a synergistic effect, whereas tamoxifen and taxanes had an antagonistic effect.ConclusionsExpression of MAPT protein isoforms of less than 70 kDa is correlated with a low sensitivity to taxanes in breast cancer cells. ER influences MAPT expression and fulvestrant increases the sensitivity to taxanes in MAPT- and ER-positive breast cancer cells.

Overexpression of UbcH10 alternates the cell cycle profile and accelerate the tumor proliferation in colon cancer

BackgroundUbcH10 participates in proper metaphase to anaphase transition, and abrogation of UbcH10 results in the premature separation of sister chromatids. To assess the potential role of UbcH10 in colon cancer progression, we analyzed the clinicopathological relevance of UbcH10 in colon cancer.MethodsWe firstly screened the expression profile of UbcH10 in various types of cancer tissues as well as cell lines. Thereafter, using the colon cancer cells line, we manipulated the expression of UbcH10 and evaluated the cell cycle profile and cellular proliferations. Furthermore, the clinicopathological significance of UbcH10 was immunohistologically evaluated in patients with colon cancer. Statistical analysis was performed using the students t-test and Chi-square test.ResultsUsing the colon cancer cells, depletion of UbcH10 resulted in suppression of cellular growth whereas overexpression of UbcH10 promoted the cellular growth and oncogenic cellular growth. Mitotic population was markedly alternated by the manipulation of UbcH10 expression. Immunohistochemical analysis indicated that UbcH10 was significantly higher in colon cancer tissue compared with normal colon epithelia. Furthermore, the clinicopathological evaluation revealed that UbcH10 was associated with high-grade histological tumors.ConclusionThe results show the clinicopathological significance of UbcH10 in the progression of colon cancer. Thus UbcH10 may act as a novel biomarker in patients with colon cancer.

Tumor inhibitory effect of gefitinib (ZD1839, Iressa) and taxane combination therapy in EGFR-overexpressing breast cancer cell lines (MCF7/ADR, MDA-MB-231)

Some kinds of breast cancer cell lines, similar to several types of solid tumors, express epidermal growth factor receptor (EGFR). However, gefitinib, an EGFR tyrosine kinase inhibitor, is not effective for all these cell lines. Similarly, taxane is effective for many of the cell lines, although some, such as the multidrug‐resistant MCF7/ADR cell line, show taxane‐resistance. Here, we examined the growth inhibitory effect of combination treatment with gefitinib and taxane on the breast cancer cell lines MDA‐MB‐231 (EGFR‐positive) and MCF7/ADR (EGFR‐ and HER2‐positive). To estimate the combined effect, a Combination Index was calculated for each cell line. The combination of gefitinib and taxane showed a strong synergistic effect on MCF7/ADR cells, but an invitro additive‐antagonistic effect on MDA‐MB‐231 cells. Similarly, the combination treatment showed a significantly increased tumor inhibitory effect on MCF7/ADR xenografts, but not on MDA‐MB‐231 xenografts. Regarding the mechanism of the synergistic effect, Western blotting analysis revealed that taxane activated the EGFR‐Akt pathway in MCF7/ADR cells but not in MDA‐MB‐231. To determine the optimal sequential administration of gefitinib and taxane for MCF7/ADR cells, we used flow cytometry to analyze the cell cycle and apoptosis; finding that taxane treatment followed by gefitinib produced a higher rate of G2 arrest and apoptosis than gefitinib treatment followed by taxane. These results suggest gefitinib overcomes the drug‐resistance of these cells, thereby increasing the effects of taxane on MCF7/ADR cells. Further, activation of the EGFR‐Akt pathway by taxane is related to this synergistic effect.

Combination treatment with fulvestrant and various cytotoxic agents (doxorubicin, paclitaxel, docetaxel, vinorelbine, and 5-fluorouracil) has a synergistic effect in estrogen receptor-positive breast cancer

Patients with estrogen receptor (ER)‐positive breast cancers have a better prognosis than those with ER‐negative breast cancers, but often have low sensitivity to chemotherapy and a limited survival benefit. We have previously shown a combination effect of taxanes and fulvestrant and suggested that this treatment may be useful for ER‐positive breast cancer. In this study, we evaluated the effects of combinations of hormone drugs and chemotherapeutic agents. In vitro, the effects of combinations of five chemotherapeutic agents (doxorubicin, paclitaxel, docetaxel, vinorelbine, and 5‐fluorouracil) and three hormone drugs (fulvestrant, tamoxifen, and 4‐hydroxytamoxifen) were examined in ER‐positive breast cancer cell lines using CalcuSyn software. Changes in chemoresistant factors such as Bcl2, multidrug resistance‐associated protein 1, and microtubule‐associated protein tau were also examined after exposure of the cells to hormone drugs. In vivo, tumor sizes in mice were evaluated after treatment with docetaxel or doxorubicin alone, fulvestrant alone, and combinations of these agents. Combination treatment with fulvestrant and all five chemotherapeutic agents in vitro showed synergistic effects. In contrast, tamoxifen showed an antagonistic effect with all the chemotherapeutic agents. 4‐Hydroxytamoxifen showed an antagonistic effect with doxorubicin and 5‐fluorouracil, but a synergistic effect with taxanes and vinorelbine. Regarding chemoresistant factors, Bcl2 and microtubule‐associated protein tau were downregulated by fulvestrant. In vivo, a combination of fulvestrant and docetaxel had a synergistic effect on tumor growth, but fulvestrant and doxorubicin did not show this effect. In conclusion, fulvestrant showed good compatibility with all the evaluated chemotherapeutic agents, and especially with docetaxel, in vitro and in vivo. (Cancer Sci 2011; 102: 2038–2042)

Feasibility study of docetaxel with cyclophosphamide as adjuvant chemotherapy for Japanese breast cancer patients.

OBJECTIVE The 7-year follow-up of the US oncology 9735 trial demonstrated the superiority of TC [docetaxel (DTX)/cyclophosphamide (CPA)] to doxorubicin/CPA therapy. To introduce TC therapy in Japan, the verification of the safety and tolerability is essential. We performed a collaborative prospective safety study with Okayama University to introduce TC therapy. METHODS The subjects were 53 patients aged from 33 to 67 years at intermediate risk based on the St Gallen risk classification who underwent radical surgery for primary breast cancer between August 2007 and December 2008. As post-operative adjuvant chemotherapy, four cycles of TC (DTX 75 mg/m(2) + CPA 600 mg/m(2)) were administered at 3-week intervals. Adverse events were evaluated based on National Cancer Institute-Common Terminology Criteria for Adverse Events ver. 3.0. The safety and completion rate were evaluated as the primary and secondary endpoints, respectively. RESULTS Regarding hematological toxicity, Grade (G) 4 neutropenia occurred in 71.7% and G3 in 26.4%. G3-4 leukopenia developed in 32.1% and 56.6%, respectively, G4 anemia in 1.9% and G1-2 anemia in 26.4%. Regarding non-hematological toxicity, systemic malaise, skin eruption, edema, myalgia, arthralgia and nausea were noted in most patients. The completion rate was 94.3%, dose reduction was necessary in 7.5% and granulocyte colony-stimulating factor (G-CSF) support was required in 17.0%. On comparison between patients aged 65 years or older and younger than 65 years, the completion rate, dose reduction and incidence of febrile neutropenia (FN) were higher in the elderly patients. G-CSF support was more often needed in this subgroup. CONCLUSIONS TC therapy is tolerable for Japanese patients, but attention should be paid to the development of FN and neutropenia. The completion rate was lower in the elderly patients, showing that tolerability was not necessarily favorable.

PLC and PI3K Pathways are Important in the Inhibition of EGF-Induced Cell Migration by Gefitinib ('Iressa', ZD1839)

BackgroundExpression of epidermal growth factor receptor (EGFR) by human breast cancer tissues is associated with poor clinical response. The EGFR tyrosine kinase inhibitor (EGFR-TKI), gefitinib (‘Iressa’, ZD1839), is a leading example of a molecular targeted agent, and has an anti-proliferative effect on various cancer cells. But the details of the anti-cancer effect and mechanism have not been elucidated. We studied the anti-cancer effect of gefitinib in breast cancer cell lines and the intracellular pathway downstream of EGFR associated with cell migration.MethodsIn this study, we analysed the anti-proliferative and anti-migratory effect of gefitinib in EGFR (+) breast cancer cell lines by WST-1 analysis and chemotaxis chamber analysis. We analyzed several intracellular phosphorylated pathways which are activated by mitogen activated kinases (extracellular signal-regulated protein kinase 1 and 2: MEK), phosphatidylinositol 3’-kinase (PI3K) and phpspholipase C (PLC), by blocking those pathways using inhibitors of each kinase, and also investigated the effects on the phosphorylation of myosin light chain (MLC).ResultsGefitinib inhibited proliferation in most of these cell lines. MDA-MB231 was shown to be resistant. Furthermore, proliferation of MDA-MB231 cells was not affected by EGF stimulation, but migration of MDA-MB231 cells was significantly inhibited. PI3K and PLC inhibitors blocked EGF-stimulated cell migration and MLC phosphorylation, but the MEK inhibitor did not influence cell migration.ConclusionsGefitinib has an anti-migratory effect on MDA-MB231 that results in an anti-proliferative effect. PI3K and PLC are important for the migration of MDA-MB231 cells, and gefitinib may inhibit migration by blocking these signalling pathways.

Evaluation of Trastuzumab Without Chemotherapy as a Post-operative Adjuvant Therapy in HER2-positive Elderly Breast Cancer Patients: Randomized Controlled Trial [RESPECT (N-SAS BC07)]†

OBJECTIVE This trial is conducted to investigate the benefit of trastuzumab monotherapy compared with a combination therapy of trastuzumab and chemotherapy in women over 70 years with human epidermal growth factor receptor type-2-positive primary breast cancer. METHODS Inclusion criteria are the following: histologically diagnosed as invasive breast cancer and received curative operation for primary breast cancer; Stage I, IIA, IIB or IIIA/M0; and baseline left ventricular ejection fraction is ≥55%. Patients are randomized to receive either trastuzumab (8 mg/kg loading dose, 6 mg/kg every 3 weeks for 1 year) plus chemotherapy selected from regimens specified on the protocol or trastuzumab monotherapy. The primary endpoint is disease-free survival. Secondary endpoints are overall survival, relapse-free survival, safety, health-related quality of life, comprehensive geriatric assessment and cost effectiveness. RESULTS Patients recruitment has been commenced in October 2009. Enrollment of 300 patients is planned during the 4-year recruitment period. CONCLUSIONS We hereby report the study concept.

Factors Associated with Health-related Quality-of-life in Breast Cancer Survivors: Influence of the Type of Surgery

OBJECTIVE To determine if health-related quality-of-life (QOL) differences existed between breast cancer (BC) survivors receiving mastectomy and those receiving breast-conserving treatment (BCT). Factors associated with QOL in long-term BC survivors were also identified. METHODS One hundred patients who had previously undergone BC surgery and were alive without recurrence for >5 years were asked to answer the patient-administered questionnaires to assess their QOL (Functional Assessment of Cancer Therapy scale-Breast: FACT-B) and psychological distress (Hospital Anxiety and Depression Scale: HADS). Of them, 93 responded to the questionnaires affirmatively. RESULTS Although none of the QOL scores were related to the surgical procedures, statistically significant relationships were found between age and the scores of FACT-General and social/family well-being (SWB), and between the educational status and scores of SWB in univariate analyses. There was no statistically significant relationship between psychological distress and each factor examined. In multivariate analyses, significant correlations were established between scores of the FACT-BC subscale (FACT-BCS) and the type of surgery and between those on the FACT SWB subscale and age at study or educational status. Namely, patients who had undergone BCT, younger patients and patients with higher educational background scored higher QOL. CONCLUSIONS Among the BC survivors, those who underwent BCT experienced significantly but slightly better QOL than those who received mastectomy in FACT-BCS assessments. Younger patients and patients with higher educational backgrounds experienced significantly better SWB.

Clinicopathological relevance of UbcH10 in breast cancer

Abrogated mitotic progression is a common hallmark of cancer. UbcH10, one of the components of the ubiquitin/proteasome pathway, plays a pivotal role in the regulation of mitotic progression. Abnormal UbcH10 activity is reported in certain types of human cancers; its overexpression is occasionally encountered in cancerous tissue compared with adjacent normal tissue. Current studies have suggested the critical role of UbcH10 in the spindle assembly checkpoint and the subsequent accurate separation of sister chromatids, which is orchestrated by a series of molecular interactions governed by the complex and diverse cell cycle machinery. To validate the potential role of UbcH10 in cell proliferation in cancer, we have analyzed the clinicopathological relevance of UbcH10 in progression of breast cancer using a combinatorial approach of human tumor arrays and biochemical analyses. Our results show that the percentage of tested samples which stained positive for UbcH10 in breast cancer tissues is significantly higher compared to the adjacent nonmalignant tissue. Furthermore, results from the clinicopathological analysis have revealed that elevated expression of UbcH10 is associated with higher histological grade tumors. In addition, depletion of UbcH10 by RNA interference in breast cancer cells resulted in decreased cellular proliferation, while overexpression of UbcH10 significantly enhanced cellular growth in breast cancer. Our results suggest a pathological correlation between UbcH10 and cell proliferation in breast cancer. Thus, aberrant UbcH10 activity may induce the dysfunction of proper cell cycle progression and result in the aggressive behavior of tumor cells in patients with breast cancer. (Cancer Sci 2009; 100: 238–248)

Effects of lifestyle and single nucleotide polymorphisms on breast cancer risk: a case–control study in Japanese women

BackgroundLifestyle factors, including food and nutrition, physical activity, body composition and reproductive factors, and single nucleotide polymorphisms (SNPs) are associated with breast cancer risk, but few studies of these factors have been performed in the Japanese population. Thus, the goals of this study were to validate the association between reported SNPs and breast cancer risk in the Japanese population and to evaluate the effects of SNP genotypes and lifestyle factors on breast cancer risk.MethodsA case–control study in 472 patients and 464 controls was conducted from December 2010 to November 2011. Lifestyle was examined using a self-administered questionnaire. We analyzed 16 breast cancer-associated SNPs based on previous GWAS or candidate-gene association studies. Age or multivariate-adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were estimated from logistic regression analyses.ResultsHigh BMI and current or former smoking were significantly associated with an increased breast cancer risk, while intake of meat, mushrooms, yellow and green vegetables, coffee, and green tea, current leisure-time exercise, and education were significantly associated with a decreased risk. Three SNPs were significantly associated with a breast cancer risk in multivariate analysis: rs2046210 (per allele OR = 1.37 [95% CI: 1.11-1.70]), rs3757318 (OR = 1.33[1.05-1.69]), and rs3803662 (OR = 1.28 [1.07-1.55]). In 2046210 risk allele carriers, leisure-time exercise was associated with a significantly decreased risk for breast cancer, whereas current smoking and high BMI were associated with a significantly decreased risk in non-risk allele carriers.ConclusionIn Japanese women, rs2046210 and 3757318 located near the ESR1 gene are associated with a risk of breast cancer, as in other Asian women. However, our findings suggest that exercise can decrease this risk in allele carriers.