Yoshiaki Ando

HDAC6 expression is correlated with better survival in breast cancer

Purpose: The structure and function of chromatin can be altered by modifications to histone. Histone acetylation in vivo is a dynamic reversible process governed by histone acetyltransferases (HATs) and histone deacetylases (HDACs). HDAC6 is a unique isoform among the HDACs, and a gene expression pattern study, with cDNA microarray in MCF-7 cells, showed the HDAC6 gene to be late responsive, estrogen induced, and up-regulated. This led us to hypothesize that there was a link between levels of HDAC6 expression and the metastatic potential of breast cancer and also, therefore, the prognosis of these patients. Experimental Design: In the present study, the level of HDAC6 mRNA expression was analyzed with quantitative real-time reverse transcription-PCR, in 135 female patients with invasive breast cancer. HDAC6 protein expression was also determined by immunohistochemistry. An association was sought between HDAC6 expression and various clinicopathologic factors. Results: HDAC6 mRNA was expressed at significantly higher levels in breast cancer patients with small tumors measuring less than 2 cm, with low histologic grade, and in estrogen receptor α- and progesterone receptor-positive tumors. By contrast, no relationship was found between HDAC6 mRNA expression and any of the other clinicopathologic factors, namely, age, menopausal status, and axillary lymph node involvement. Patients expressing high levels of HDAC6 mRNA and protein had a better prognosis than those expressing low levels, in terms of disease-free survival. However, multivariate analysis failed to show that HDAC6 mRNA and protein are an independent prognostic factors for disease-free survival and overall survival. Furthermore, the patients with high levels of HDAC6 mRNA tended to be more responsive to endocrine treatment than those with low levels. Specific HDAC6 staining was found in the nucleus of some normal epithelial cells and in the cytoplasm of the majority of cancer cells. Although postmenopausal patients showed higher HDAC6 protein expression, there were no relationship between protein expression and any other clinicopathologic factors. Conclusions: We conclude that the levels of HDAC6 mRNA expression may have potential both as a marker of endocrine responsiveness and also as a prognostic indicator in breast cancer. Additional investigations are warranted concerning the relationship between HDAC6 expression and response to endocrine therapy.

Phosphorylation of estrogen receptor α serine 167 is predictive of response to endocrine therapy and increases postrelapse survival in metastatic breast cancer

IntroductionEndocrine therapy is the most important treatment option for women with hormone-receptor-positive breast cancer. The potential mechanisms for endocrine resistance involve estrogen receptor (ER)-coregulatory proteins and crosstalk between ER and other growth factor signaling networks. However, the factors and pathways responsible for endocrine resistance are still poorly identified.MethodsUsing immunohistochemical techniques, we focused on the expression and phosphorylation of hormone receptors themselves and examined the phosphorylation of ER-α Ser118 and ER-α Ser167 and the expression of ER-α, ER-β1, ER-βcx/β2, progesterone receptor (PR), PRA, and PRB in the primary breast carcinomas of 75 patients with metastatic breast cancer who received first-line treatment with endocrine therapy after relapse.ResultsPhosphorylation of ER-α Ser118, but not Ser167, was positively associated with overexpression of HER2, and HER2-positive tumors showed resistance to endocrine therapy. The present study has shown for the first time that phosphorylation of ER-α Ser167, but not Ser118, and expression of PRA and PRB, as well as ER-α and PR in primary breast tumors are predictive of response to endocrine therapy, whereas expression of ER-β1 and ER-βcx/β2 did not affect response to the therapy. In addition, patients with either high phosphorylation of ER-α Ser167, or high expression of ER-α, PR, PRA, or PRB had a significantly longer survival after relapse.ConclusionThese data suggest that phosphorylation of ER-α Ser167 is helpful in selecting patients who may benefit from endocrine therapy and is a prognostic marker in metastatic breast cancer.

DNA methylation analysis at distal and proximal promoter regions of the oestrogen receptor gene in breast cancers

SummaryOestrogen receptor α (ER-α) gene has two specific promoters, distal (P0) and proximal (P1), which induce almost identical transcripts in size due to different splicing. We examined the methylation at both promoter regions of the ER-α gene using HpaII, a methylation-sensitive restriction enzyme, prior to polymerase chain reaction (PCR) amplification. To confirm the results of PCR-based methylation analysis, Southern hybridization was also performed. Twenty of 29 patients with ER-α-positive tumours and five of 27 with ER-α-negative tumours were unmethylated at the P1 promoter region of the ER-α gene. The incidence of methylation was highly negatively correlated with ER-α expression (P = 0.0002). A similarly negative correlation was observed at the P0 promoter region of the ER-α gene (P = 0.0154). Additionally, the tumours with the ER-α gene hypermethylated at both promoter regions had definitely negative ER-α values. It was suggested that this epigenetic change might control ER-α expression, and might play an important role in the loss of hormone-dependence in breast cancer.

Reproductive history and breast cancer risk

The fact that reproductive factors have significant influence on the risk of breast cancer is well known. Early age of first full-term birth is highly protective against late-onset breast cancers, but each pregnancy, including the first one, increases the risk of early-onset breast cancer. Estradiol and progesterone induce receptor activator of NF-kappa B ligand (RANKL) in estrogen receptor (ER)- and progesterone receptor (PgR)-positive luminal cells. RANKL then acts in a paracrine fashion on the membranous RANK of ER/PgR-negative epithelial stem cells of the breast. This reaction cascade is triggered by chorionic gonadotropin during the first trimester of pregnancy and results in the morphological and functional development of breast tissue. On the other hand, the administration of non-steroidal anti-inflammatory drugs in the early steps of weaning protects against tumor growth through reduction of the acute inflammatory reaction of post lactation remodeling of breast tissue. This is experimental evidence that may explain the short-term tumor-promoting effect of pregnancy. The protective effect of prolonged breast feeding may also be explained, at least in a part, by a reduced inflammatory reaction due to gradual weaning. Delay of first birth together with low parity and short duration of breast feeding are increasing social trends in developed countries. Therefore, breast cancer risk as a result of reproductive factors will not decrease in these countries in the foreseeable future. In this review, the significance of reproductive history with regard to the risk of breast cancers will be discussed, focusing on the age of first full-term birth and post lactation involution of the breast.

p53 protein accumulation predicts resistance to endocrine therapy and decreased post-relapse survival in metastatic breast cancer

IntroductionEndocrine therapy is the most important treatment option for women with hormone receptor-positive breast cancer. The potential mechanisms for endocrine resistance involve estrogen receptor (ER)-coregulatory proteins and cross-talk between ER and other growth factor-signaling networks. However, the factors and pathways responsible for endocrine resistance are still poorly identified.Materials and methodsThe expression of HER2, p53, and Ki67 was examined by immunohistochemistry in primary breast tumour specimens from 73 metastatic breast cancer patients who received first-line treatment with endocrine therapy on relapse, and analysed to determine whether expression of these molecular markers affected the response to endocrine therapy.ResultsOf the 73 invasive ductal carcinomas, 12.3%, 21.9%, and 35.6% were positive for HER2 overexpression, p53 protein accumulation, and Ki67 expression, respectively. All patients received endocrine therapy as first-line treatment for metastatic breast cancer; 34 patients (46.6%) responded. Patients with primary breast tumours that had p53 protein accumulation and Ki67 expression showed significantly more resistance to endocrine therapy (P = 0.0049 and P = 0.024, respectively). There were also tendencies for HER2 overexpression to correlate with resistance to endocrine therapy, but this did not reach significance. p53 protein accumulation and HER2 overexpression significantly reduced post-relapse survival (P < 0.0001 and P = 0.001, respectively), and these factors were also statistically significant in a multivariate analysis.ConclusionThese data suggest that p53 protein accumulation is helpful in selecting patients who may benefit from endocrine therapy and is a prognostic marker in hormone receptor-positive metastatic breast cancer.

Predictors of response to exemestane as primary endocrine therapy in estrogen receptor–positive breast cancer

Endocrine therapy is the most important treatment of choice for estrogen receptor (ER)‐positive breast cancer. Potential mechanisms for resistance to endocrine therapy involve ER‐coregulatory proteins and cross‐talk between ER and other growth factor–signaling networks. However, the factors and pathways responsible for endocrine therapy resistance, particularly resistance to aromatase inhibitors, have not been clearly established. Sixteen postmenopausal patients with ERα‐positive primary breast cancer were treated daily with 25 mg of exemestane (an aromatase inhibitor) for 6 months. Expressions of ERα, ERβ, progesterone receptor (PgR), androgen receptor (AR), amplified in breast cancer 1 (AIB1), aromatase, epidermal growth factor receptor, human epidermal growth factor receptor type 2, Ki67, cyclin D1, p53, Bcl2, signal transducer and activator of transcription 5 (Stat5), and insulin‐like growth factor binding protein 5 (IGFBP5), and phosphorylations of ERα serine (Ser) 118, ERα Ser167, Akt Ser473, and p44/42 MAPK threonine (Thr) 202/tyrosine (Tyr) 204, were examined by immunohistochemistry on pretreatment tumor biopsies and post‐treatment surgical specimens. Analyses were made to test for correlations with response to exemestane. Of the 16 patients, seven responded and nine retained stable disease. High‐level expression of AIB1 and phosphorylation of Akt Ser473 were significantly associated with a better response to exemestane, suggesting that these factors could be considered as predictors of exemestane response. Expressions of ERα, ERβ, PgR, aromatase, Ki67, cyclin D1, and p53, and phosphorylations of ERα Ser118, ERα Ser167, and p44/42 MAPK Thr202/Tyr204, were decreased, whereas expressions of Stat5 and IGFBP5 were increased in post‐treatment specimens compared to the values in pretreatment biopsies. Thus, the analysis of factors involved in the estrogen‐dependent growth‐signaling pathways may be useful in identifying patients responsive to exemestane. (Cancer Sci 2009)

Loss of heterozygosity and microsatellite instability in ductal carcinoma in situ of the breast

To investigate the alterations of genetic instabilities in carcinogenesis of the breast, we analyzed the allelotypic profile of 65 ductal carcinomas in situ (DCIS), compared with that of 207 invasive ductal carcinomas (IDC) of the breast. These studies were performed by means of examining microsatellite-length polymorphisms at seven loci (AluVpa, ESR, D11S988, D13S267, D16S398, D17S1159, and D17S855) from microdissected paraffin sections. Allelic loss or imbalance, considered a loss of heterozygosity (LOH), tended to be more frequently seen in IDC than in DCIS. In particular, the frequency of LOH at the 17p locus was significantly higher in IDC than in DCIS (42 vs. 23%, P=0.022). LOH in DCIS was most frequently seen at D16S398 (26%). LOH frequency at D16S398 in low- and intermediate-grade DCIS was higher than that in high-grade DCIS, while LOH frequencies at D11S988 and D17S1159 in low- and intermediate-grade DCIS was lower than those in high-grade DCIS. LOH frequency at D11S988 in non-comedo type DCIS was lower than that in comedo type DCIS. Furthermore, the frequency of microsatellite instability (MSI) at only one locus in DCIS (28%) was statistically higher than that in IDC (6%) (P<0.001), while there was no difference between the frequency of MSI at multiple loci in DCIS (6%) and that in IDC (3%). Together, these observations indicate that chromosomal losses of 16q may occur in low- and intermediate-grade DCIS and those of 11p and 17p may occur high-grade DCIS, and that MSI occurring at only one locus is not yet clear and MSI at multiple loci is uncommon in not only IDC but also DCIS of the breast.

Immunohistochemical analysis on biological markers in ductal carcinoma in situ of the breast

BackgroundThe increasing use of mammographic screening has led to an increased detection of ductal carcinomain situ (DCIS) of the breast. The detailed biological characteristics of DCIS and a new classification of DCIS based on these characteristics are needed.MethodsImmunohistochemical studies were performed to assess the expression of c-erbB-2 (ErbB-2), estrogen receptor (ER), p53 and proliferative activity (Ki-67) in 65 patients with pure DCIS and 60 with invasive ductal carcinoma (IDC). We classified pure DCIS tumors using three classifications, the architectural, Nottingham, and Van Nuys classifications.ResultsErbB-2, ER and p53 staining was positive in 34%, 66% and 21% of patients with DCIS, respectively, and 58%, 42% and 33% in patients with IDC, respectively. Ki-67 stained positively in 1.5 % of patients with DCIS and 11.2 % of patients with IDC. The comedo type showed a high rate of positive ErbB-2 and p53 staining. The cribriform and papillary types showed a high rate of positive ER staining. Under the Van Nuys classification, ErbB-2, p53 and Ki-67 expression were highest in the group with high nuclear grade and lowest in the group with non-high nuclear grade without necrosis.ConclusionAlthough the biological markers of IDC tended to suggest aggressive behavior more so than those of DCIS, these differences were based on the histological sub-type, comedo or non-comedo. The Van Nuys classification best defined the subgroups of DCIS with a distinct expression pattern of biological markers, and the best candidates for breast-conserving surgery.

Genetic and Epigenetic Alterations of the Estrogen Receptor Gene and Hormone Independence in Human Breast Cancer

The existence of hormone-independent tumors is a substantial problem for the present endocrine treatment of breast cancers. Estrogen receptor (ER) gene mutation can change the biochemical activity of the protein and can affect hormone responsiveness. However, quite a few mutations of significance have been described in breast cancer. Recently, numerous variant ERs have been detected at the mRNA level with alternative splicing, yielding deletion of exon 3, 5, or 7. The truncated ER protein induced from variant mRNA could mainly be exhibited as a repressor through dominant negative effects on normal ER protein. The mechanism of the loss of hormone dependency is, however, still very complex. Further work to assess the correlation between clinical behavior and ER variants is required to determine whether these variants play a role in hormone-resistant disease. Additionally, the DNA methylation of the ER gene itself may control ER expression. These epigenetic changes can play an important role in the loss of hormone dependence in breast cancer.

Comparison of five different antibodies in the immunohistochemical assay of estrogen receptor α in human breast cancer

BackgroundEstrogen receptor α(ER) expression is the best prognostic and predictive factor of hormone dependency of human breast cancers. Unlike enzyme immunoassay (EIA), which has been widely used to evaluate ER status in breast cancer, immunohistochemical assay (IHC) can detect ER in a small amounts of tissue with detailed localization. Although there is a sufficient number of ER antibodies against various regions of the protein, the reliability of IHC staining is only well understood for a few. IHC and EIA for the evaluation of the ER status of human breast cancer, therefore, should be compared using the same breast cancer tissues.MethodsFive different ER antibodies (1D-5, C-314, G-20, C-311 and HC-20) that identify different amino acid sequences were used. The evaluation of ER status by IHC using these antibodies was compared with EIA concomitantly in 97 primary human breast cancer tissues.ResultsThe positiviry rate for EIA was 68%. That of IHC for antibodies 1D-5, C-314, G-20, C-311 and HC-20 was 50.5%, 47.4%, 46.4%, 44.3% and 57.7%, respectively. The concordance between EIA was 76.3% for 1 D-5 and 77.3% for HC-20, which is statistically highly significant (p<0.0001); Other antibodies were not.ConclusionsHC-20 is most suitable in the evaluation of the ER status of human breast cancers using the IHC method. Although antibody 1 D-5 is also available, C-314, G20 and C-311 are unreliable in such an evaluation.