Heterogeneous Nuclear Ribonucleoprotein K Is Involved in the Estrogen-Signaling Pathway in Breast Cancer.

Heterogeneous nuclear ribonucleoprotein K (hnRNPK) transcripts are abundant in estrogen receptor (ER)- or progesterone receptor (PR)-positive breast cancer. However, the biological functions of hnRNPK in the ER-mediated signaling pathway have remained largely unknown. Therefore, this study analyzes the functions of hnRNPK expression in the ER-mediated signaling pathway in breast cancer. We initially evaluated hnRNPK expression upon treatment with estradiol (E2) and ICI 182,780 in the ERα-positive breast carcinoma cell line MCF-7. The results revealed that E2 increased hnRNPK; however, hnRNPK expression was decreased with ICI 182,780 treatment, indicating estrogen dependency. We further evaluated the effects of hnRNPK knockdown in the ER-mediated signaling pathway in MCF-7 cells using small interfering RNAs. The results revealed that hnRNPK knockdown decreased ERα expression and ERα target gene pS2 by E2 treatment. As hnRNPK interacts with several other proteins, we explored the interaction between hnRNPK and ERα, which was demonstrated using immunoprecipitation and proximity ligation assay. Subsequently, we immunolocalized hnRNPK in patients with breast cancer, which revealed that hnRNPK immunoreactivity was significantly higher in ERα-positive carcinoma cells and significantly lower in Ki67-positive or proliferative carcinoma cells. These results indicated that hnRNPK directly interacted with ERα and was involved in the ER-mediated signaling pathway in breast carcinoma. Furthermore, hnRNPK expression could be an additional target of endocrine therapy in patients with ERα-positive breast cancer.

Impact of Topoisomerase IIα, PTEN, ABCC1/MRP1, and KI67 on triple-negative breast cancer patients treated with neoadjuvant chemotherapy.

PURPOSE: Triple-negative breast cancer (TNBC) patients with residual disease following neoadjuvant chemotherapy (NAC) harbor higher risk of relapse, and eventual demise compared to those who achieve pathologic complete response. Therefore, in this study, we assessed a panel of molecules involved in key pathways of drug resistance and tumor progression before and after NAC in TNBC patients, in order to clarify the underlying mechanisms. METHODS: We studied 148 TNBC Japanese patients treated with anthracycline/taxane-based NAC. KI67, Topoisomerase IIα (TopoIIα), PTEN, p53, Bcl2, vimentin, ABCG2/BCRP1, ABCB1/MDR1, and ABCC1/MRP1 were immunolocalized in surgical pathology materials before and after NAC. RESULTS: The status of vimentin and increasing labeling index (LI) of TopoIIα and KI67 in biopsy specimens were significantly associated with those who responded to NAC treatment. The abundance of p53 (p = 0.003), ABCC1/MRP1 (p = 0.033), ABCB1/MDR1 (p = 0.022), and a loss of PTEN (p < 0.0001) in surgery specimens following treatment were associated with pathologic parameters. TopoIIα, PTEN, and ABCC1/MRP1 status predicted pathologic response. In addition, the status of PTEN, ABCC1/MRP1, ABCB1/MDR1, Bcl2, and vimentin in surgical specimens was also significantly associated with adverse clinicopathological factors in surgery specimens, suggesting that these alterations could be responsible for tumor relapse in TNBC patients. CONCLUSION: KI67, TopoIIα, PTEN, and ABCC1/MRP1 status could predict treatment response and/or eventual clinical outcomes. These results could also provide an insight into the mechanisms of drug resistance and relapse of TNBC patients receiving NAC.

The interaction between carcinoembryonic antigen-related cell adhesion molecule 6 and human epidermal growth factor receptor 2 is associated with therapeutic efficacy of trastuzumab in breast cancer.

Human epidermal growth factor receptor 2 (HER2) is a target of the HER2 inhibitor trastuzumab, which has been administered to HER2-positive breast cancer patients. However, the therapeutic effects of HER2 inhibitor monotherapy are not always clinically effective as compared with cotreatment with chemotherapy. Therefore, it has become pivotal to predict the therapeutic efficacy of trastuzumab monotherapy prior to administration. Recently, carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) has been reported to be a HER2-related factor. The aim of the present study was to explore the therapeutic mechanism of trastuzumab, including the relevance of CEACAM6 expression. CEACAM6/HER2-double-positive human breast carcinoma cell lines BT-474, HCC-1419 and MDA-MB-361 were used in this study. CEACAM6 knockdown decreased the inhibitory effects of trastuzumab in the trastuzumab-sensitive BT-474 and HCC-1419 cells, but not in the trastuzumab-resistant MDA-MB-361 cells. We examined the interaction between CEACAM6 and HER2 by using a proximity ligation assay (PLA). The interaction was detected in BT-474 and HCC-1419 cells, but not in MDA-MB-361 cells, and was significantly associated with in vitro trastuzumab therapeutic sensitivity. We further analysed the status of CEACAM6 and HER2 and their interaction in archival pathology specimens, also using PLA. The interaction was detected only in CEACAM6/HER2-double-positive breast cancer cases, and their PLA score was significantly associated with the efficacy of trastuzumab treatment. Therefore, evaluation of the CEACAM6-HER2 interaction could serve as a marker to predict the efficacy of trastuzumab monotherapy in breast cancer patients. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The significance of lipid accumulation in breast carcinoma cells through perilipin 2 and its clinicopathological significance.

Both systemic and intratumoral lipid metabolism have been recently reported to play pivotal roles in both tumor development and progression in various human malignancies including breast cancer. However, its details have remained largely unknown in breast cancer patients. Therefore, in this study, we focused on perilipin 2, which is involved in constituting the intracellular lipid composition. Perilipin 2 was first immunolocalized in 105 cases of breast cancer. The status of perilipin 2 immunoreactivity was significantly positively associated with histological grade, Ki-67 labeling index and HER2 status and negatively with estrogen receptor status of these patients. Subsequent in vitro study also revealed that its mRNA expression in triple negative breast carcinoma cells was higher than cells of other subtypes. We then examined the correlation between perilipin 2 immunoreactivity and intracellular lipid droplet evaluated by Oil-red O stating in 13 cases of breast carcinoma tissues. A significantly positive correlation was detected between the status of perilipin 2 and Oil-red O staining. These findings above did indicate that perilipin 2 could represent the status of intracellular lipid droplets in surgical pathology specimens of breast cancer and perilipin 2 was also associated with its more aggressive biological phenotypes.

Newly-Developed Positron Emission Mammography (PEM) Device for the Detection of Small Breast Cancer.

Positron emission mammography (PEM) has higher detection sensitivity for breast cancer compared with whole-body positron emission tomography (PET) due to higher spatial resolution. We have developed a new PEM device with high resolution over a wide field of view. This PEM device comprises novel scintillation crystals, praseodymium-doped lutetium aluminum garnet (Pr:LuAG). In the present study, the clinical use of the newly developed PEM for the detection of small breast cancer was compared with that of the conventional PET-computed tomography (PET/CT). Eighty-two patients with breast cancer less than 20 mm (UICC T1) participated in this study, including 23 patients with T1a or T1b breast cancer (less than 10 mm). Histologically-proved lesions were examined by PET/CT and PEM on the same day after injection of [18F]fluoro-2-deoxy-2-fluoro-D-glucose ([18F]FDG), a marker of glycolytic activity. The newly developed PEM showed better sensitivity of cancer detection compared with PET/CT especially in case of the small T1a or T1b lesions. Moreover, when the conventional PET/CT and new PEM were combined, the detection sensitivity with [18F]FDG molecular imaging for T1 (N = 82) and T1a plus T1b breast cancer (N = 23) were 90% and 70%, respectively. The uptake of [18F]FDG was proportional to the histological malignancy of breast cancer. Using the newly-developed PEM with [18F]FDG, we are able to identify and characterize exactly the small breast tumors less than 10 mm in combination with the conventional PET/CT. These data indicate that PEM and PET/CT are synergic and complementary for the detection of small breast cancer.

The presence and impact of estrogen metabolism on the biology of triple-negative breast cancer.

PURPOSE: While triple-negative breast cancer (TNBC) is negative for estrogen receptor alpha, a substantial proportion of carcinomas express estrogen receptor beta (ERß); consequently, estrogen actions and metabolism may be relevant in this cancer subtype. METHODS: A cohort of 81 TNBC patients from Tohoku University Hospital, Japan were characterised with regard to the expression of estrogen receptor beta and enzymes known to modulate levels of estrogens in breast and other tissues (Aromatase, 17-beta- Hydroxysteroid dehydrogenases 1, 2 and 6). This was done at the protein level by means of immunohistochemistry. As this cohort has been previously characterised for androgens, this also allows for comparison between the expressions of estrogen-related proteins and of androgen-related proteins. Preliminary mechanistic studies in cell culture were also undertaken. RESULTS: 17ßHSD2 was detected in the highest number of cases followed by 17ßHSD1, 17ßHSD6 and aromatase. When comparing the expression of ERß with that of the enzymes, it was positively correlated with the expression of 17ßHSD6 (p < 0.05) and trended towards correlation with dual expression of 17ßHSD1 and 2 (p < 0.07). 17ßHSD1 was associated with significantly reduced tumour volume (p = 0.0025), while ERß was associated with a trend towards reduced lymphovascular invasion, (p < 0.061). Interestingly, in survival analysis, 17ßHSD6 expression was the only one of these five factors that influenced survival, with positive samples being associated with longer disease-free survival compared to those that were negative for 17ßHSD6 (p < 0.05). In assessing associations with expression of proteins in the androgenic pathway, expression of aromatase appeared to be associated with androgenic pathways in TNBC patients (p < 0.05). Due to this association and the potential relevance to androgen-directed therapies in TNBC, we evaluated this interaction in vitro. We observed androgen-dependent upregulation of aromatase and ERß in a subset of AR expressing TNBC cell lines (MDA-MB-453, SUM-185-PE and MFM-223). CONCLUSION: Overall this study suggests the presence of, and a potential protective effect of estrogens in TNBC.

Intratumoral estrogen production and actions in luminal A type invasive lobular and ductal carcinomas.

The great majority of invasive lobular carcinoma (ILC) is estrogen-dependent luminal A type carcinoma but the details of estrogen actions and its intratumoral metabolism have not been well studied compared to invasive ductal carcinoma (IDC). We first immunolocalized estrogen-related enzymes including estrogen sulfotransferase (EST), estrogen sulfatase (STS), 17ß-hydroxysteroid dehydrogenase (HSD) 1/2, and aromatase. We then evaluated the tissue concentrations of estrogens in ILC and IDC and subsequently estrogen-responsive gene profiles in these tumors in order to explore the possible differences and/or similarity of intratumoral estrogen environment of these two breast cancer subtypes. The status of STS and 17ßHSD1 was significantly lower in ILCs than IDCs (p = 0.022 and p < 0.0001), but that of EST and 17ßHSD2 vice versa (p < 0.0001 and p = 0.0106). In ILCs, tissue concentrations of estrone and estradiol were lower than those in IDCs (p = 0.0709 and 0.069). In addition, the great majority of estrogen response genes tended to be lower in ILCs. Among those genes above, FOXP1 was significantly higher in ILCs than in IDCs (p = 0.002). FOXP1 expression was reported to be significantly higher in relapse-free IDC patients treated with tamoxifen. Therefore, tamoxifen may be considered an option of endocrine therapy for luminal A type ILC patients. This is the first study to demonstrate the detailed and comprehensive status of intratumoral production and metabolism of estrogens and the status of estrogen response genes in luminal A-like ILC with comparison to those in luminal A-like IDCs.

Tumor microenvironment in invasive lobular carcinoma: possible therapeutic targets.

Invasive ductal and lobular carcinomas (IDC and ILC) are the two most common histological types of breast cancer, and have been considered to develop from terminal duct lobular unit but their molecular, pathological, and clinical features are markedly different between them. These differences could be due to different mechanisms of carcinogenesis and tumor microenvironment, especially cancer-associated fibroblasts (CAFs) but little has been explored in this aspect. Therefore, in this study, we evaluated the status of angiogenesis, maturation of intratumoral microvessels, and proliferation of CAFs using immunohistochemistry and PCR array analysis to explore the differences of tumor microenvironment between ILC and IDC. We studied grade- and age-matched, luminal-like ILC and IDC. We immunolocalized CD34 and αSMA for an evaluation of CAFs and CD31, Vasohibin-1, a specific marker of proliferative endothelial cells and nestin, a marker of pericytes for studying the status of proliferation and maturation of intratumoral microvessel. We also performed PCR array analysis to evaluate angiogenic factors in tumor stromal components. The number of CAFs, microvessel density, and vasohibin-1/CD31 positive ratio were all significantly higher in ILC than IDC but nestin immunoreactivity in intratumoral microvessel was significantly lower in ILC. These results did indicate that proliferation of CAFs and endothelial cells was more pronounced in ILC than IDC but newly formed microvessels were less mature than those in IDC. PCR array analysis also revealed that IGF-1 expression was higher in ILC than IDC. This is the first study to demonstrate the differences of tumor microenvironment including CAFs and proliferation and maturation of intratumoral vessels between ILC and IDC.

Prognostic significance of tumor-infiltrating CD8+ and FOXP3+ lymphocytes in residual tumors and alterations in these parameters after neoadjuvant chemotherapy in triple-negative breast cancer: a retrospective multicenter study.

INTRODUCTION: The status of tumor-infiltrating lymphocytes (TILs) has been recently proposed to predict clinical outcome of patients with breast cancer. We therefore studied the prognostic significance of CD8(+) TILs and FOXP3(+) TILs in residual tumors after neoadjuvant chemotherapy (NAC) and the alterations in these parameters before and after NAC in patients with triple-negative breast cancer (TNBC). METHODS: One hundred thirty-one TNBC patients who received NAC at three institutions were examined. CD8(+) TIL and FOXP3(+) TIL in residual tumors and biopsy specimens were evaluated by double-staining immunohistochemistry. The CD8(+) TIL and FOXP3(+) TIL status of the residual tumors was assessed, and the rates of their changes before and after NAC were calculated. RESULTS: TNBC patients with high CD8(+) TIL levels or a high CD8/FOXP3 ratio in residual tumors had significantly better recurrence-free survival (RFS) and breast cancer-specific survival (BCSS) than patients with low values of these parameters. In multivariate analyses, CD8(+) TIL exhibited strong prognostic significance for RFS, with a hazard ratio (HR) of 3.09 (95 % confidence interval (CI) 1.537-6.614, P=0.0013). The CD8/FOXP3 ratio was also significantly correlated with RFS (HR=2.07, 95 % CI 1.029-4.436, P=0.0412). TNBC with larger residual tumor size and positive lymph node status, which are known prognostic factors, was independently associated with worse RFS (P=0.0064 and P=0.0015, respectively). High CD8(+) TIL levels were a markedly powerful indicator of improved BCSS, with an HR of 3.59 (95 % CI 1.499-9.581, P=0.0036). Nodal status was also associated with BCSS (P=0.0024). TNBC with a high rate of CD8(+) TIL changes was associated with significantly better RFS compared with the low group (P=0.011). Higher rates of changes in the CD8/FOXP3 ratio were significantly correlated with both better RFS and BCSS compared with lower rates (P=0.011 and P=0.023, respectively). CONCLUSIONS: This is the first study to demonstrate that high CD8(+) TIL and a high CD8/FOXP3 ratio in residual tumors and increment of these parameters following NAC and accurately predict improved prognosis in TNBC patients with non-pathological complete response following NAC. These parameters could serve as a surrogate one for adjuvant treatment in patients with residual disease in the neoadjuvant setting.

Intratumoral androgen metabolism and actions in invasive lobular carcinoma of the breast.

Invasive lobular carcinoma (ILC) accounts for approximately 10% of all breast carcinomas and is characterized by higher levels of androgen receptor (AR) compared to invasive ductal carcinoma (IDC). Despite this potentially androgen-responsive environment, the combined importance of AR and androgen metabolism in non-neoplastic lobules and lobular carcinoma remains unknown. Therefore, in this study, we evaluated the status of pivotal androgen-producing enzymes 17ß-hydroxysteroid dehydrogenase type 5 (17ßHSD5) and 5α-reductase type 1 (5αRed1) in 178 cases of ILC and surrounding histologically non-neoplastic lobular tissue using immunohistochemistry. Androgen receptor prevalence was higher but androgenic enzymes lower in ILC than non-neoplastic lobules. In ILC cases the status of 5αRed1 and 17ßHSD5 was inversely correlated with tumor size (P = 0.0053) and nuclear grade (P = 0.0290), and significantly associated with better overall survival of the patients (P = 0.0059). Based on these findings, we hypothesized that androgen signaling could act as a tumor suppressor. As previous studies suggested that androgens might partially act by increasing levels of the estrogen inactivating enzyme 17ß-hydroxysteroid dehydrogenase type 2 (17ßHSD2) in IDC tissues, this was reasonably considered a potential mechanism of androgen actions. Significantly positive correlation was detected between the status of androgenic enzymes and 17ßHSD2 (P < 0.0001) and intratumoral 17ßHSD2 was inversely correlated with tumor size in ILC (P = 0.0075). These correlations suggest one protective mode of androgen action could be through modulation of estrogen metabolism. Results of our present study indicated that androgen-producing enzymes could play pivotal protective roles in AR-enriched ILC cases.

Tumor-infiltrating CD8+ and FOXP3+ lymphocytes in triple-negative breast cancer: its correlation with pathological complete response to neoadjuvant chemotherapy.

The anti-tumor immune response was recently reported to play a critical role in the chemotherapeutic sensitivity of breast cancer. Therefore, we investigated the correlation between CD8+ and FOXP3+ tumor-infiltrating lymphocytes and the pathological complete response (pCR) following neoadjuvant chemotherapy (NAC) in triple-negative breast cancer (TNBC), in conjunction with neoangiogenesis, basal and proliferation markers. CD8+ and FOXP3+ lymphocytes were assessed in biopsy specimens by double-staining immunohistochemistry, in combination with immunostaining of vasohibin-1, CD31, EGFR, CK5/6, and Ki-67. Earlier age, pre-menopausal status, smaller tumor size, and high Ki-67 were significantly associated with pCR, as in high CD8+, high CD8+/FOXP3+ ratio, and low vasohibin-1 positive ratio. Multivariate analysis did reveal that a high CD8+/FOXP3+ ratio was a strong predictor of pCR with an odds ratio of 5.32 (P = 0.005). High Ki-67 was also significantly associated with pCR (P = 0.002). TNBCs with a high CD8+/FOXP3+ ratio and high Ki-67 had the highest pCR rate (70%) following NAC. However, the pCR rate of the patients with low CD8+/FOXP3+ ratio and low Ki-67 was only 5%. The pCR rates of a high CD8+/FOXP3+ ratio and low Ki-67 patients and those with a low CD8+/FOXP3+ ratio and high Ki-67 were 24 and 21%, respectively. TNBCs with a high CD8+/FOXP3+ ratio were more sensitive to anthracycline and taxane-based chemotherapeutic regimens, and the CD8+/FOXP3+ ratio in conjunction with Ki-67 could predict pCR following NAC in TNBC. This predictor may represent a new surrogate for testing the efficacy of investigational agents in the neoadjuvant setting.

Androgenic pathways in the progression of triple-negative breast carcinoma: a comparison between aggressive and non-aggressive subtypes.

One of the active intracellular pathways/networks in triple-negative breast carcinoma (TNBC) is that of the androgen receptor (AR). In this study, we examined AR and androgen-metabolising enzyme immunoreactivity in subcategories of TNBC to further elucidate the roles of androgenic pathways in TNBC. We utilised formalin-fixed paraffin-embedded breast cancer samples from ductal carcinoma in situ (DCIS) and invasive ductal carcinoma patient cohorts. We then used immunohistochemistry to classify these samples into basal-like and non-basal samples and to assess interactions between AR, androgen-metabolising enzymes and proliferation. To further substantiate our hypothesis and provide mechanistic insights, we also looked at the expression and regulation of these factors in publically available microarray data and in a panel of TNBC AR-positive cell lines. DCIS was associated with higher levels of AR and enzymes (p < 0.02), although a similar difference was not noticed in basal and non-basal samples. AR and enzymes were correlated in all states. In TNBC cell lines (MDA-MD-453, MFM-223 and SUM185-PE), we found that DHT treatment up-regulated 5αR1 and 17ßHSD5 suggesting a mechanistic explanation for the correlations observed in the histological samples. Publicly available microarray data in TNBC cases suggested similar patterns to those observed in histological samples. In the majority of settings, including publically available microarray data, an inverse association between AR and proliferation was detected. These findings suggest that decreases in AR and androgen-metabolising enzymes may be involved in the increased biological aggressiveness in TNBC development.

Aromatase inhibitor treatment of breast cancer cells increases the expression of let-7f, a microRNA targeting CYP19A1.

Aromatase inhibitors (AIs) are considered the gold standard of endocrine therapy for oestrogen receptor-positive postmenopausal breast cancer patients. AI treatment was reported to result in marked alterations of genetic profiles in cancer tissues but its detailed molecular mechanisms have not been elucidated. Therefore, we profiled miRNA expression before and after treatment with letrozole in MCF-7 co-cultured with primary breast cancer stromal cells. Letrozole significantly altered the expression profiles of cancer miRNAs in vitro. Among the elevated miRNAs following letrozole treatment, computational analysis identified let-7f, a tumour-suppressor miRNA which targeted the aromatase gene (CYP19A1) expression. Quantitative real-time PCR assay using MCF-7 and SK-BR-3 cells as well as clinical specimens of a neoadjuvant study demonstrated a significant inverse correlation between aromatase mRNA and let-7f expression. In addition, high let-7f expression was significantly correlated with low aromatase protein levels evaluated by both immunohistochemistry and the western blotting method in breast cancer cases. Results of 3'UTR luciferase assay also demonstrated the actual let-7f binding sites in CYP19A1, indicating that let-7f directly targets the aromatase gene. Subsequent WST-8 and migration assays performed in let-7f-transfected MCF-7 and SK-BR-3 cells revealed a significant decrement of their proliferation and migration. These findings all demonstrated that let-7f, a tumour suppressor miRNA in breast cancer, directly targeted the aromatase gene and was restored by AI treatment. Therefore, AIs may exert tumour-suppressing effects upon breast cancer cells by suppressing aromatase gene expression via restoration of let-7f.

Interleukin (IL)-17A in triple-negative breast cancer: a potent prognostic factor associated with intratumoral neutrophil infiltration.

BACKGROUND: Triple-negative breast cancer (TNBC) is characterized as highly immunogenic and lacks specific targeted therapies. Interleukin 17A (IL-17A) is a controversial cytokine and is known to have anti-tumor and pro-tumor roles depending on the tumor microenvironment. In addition, IL-17A has been recently implicated in the recruitments of neutrophil into tumor tissues. Although IL-17A is considered tumor-promoting in breast cancer, its significance in the possible regulation of neutrophil infiltration in TNBC is not clearly defined. MATERIALS AND METHODS: We immunolocalized IL-17A, CD66b (neutrophil marker), and chemokine (C-X-C motif) ligand 1 (CXCL1, neutrophil chemoattractant) in 108 TNBC specimens and assessed their correlation among each other. The correlation between these markers and clinicopathological parameters was also assessed. We subsequently performed in vitro study to address the possible regulation of CXCL1 by IL-17A using TNBC cell lines, MDA-MB-231 and HCC-38. RESULTS: It was revealed that IL-17A correlated significantly with CXCL1 and CD66b, also CD66b with CXCL1. Furthermore, IL-17A was significantly associated with shorter disease-free and overall survival, especially in a high density CD66b group of patients. In vitro results revealed that IL-17A upregulated CXCL1 mRNA expression in a dose and time dependent manner, and this induction was significantly suppressed by an Akt inhibitor. CONCLUSION: IL-17A was considered to contribute to neutrophil infiltration by inducing CXCL1 in TNBC tissues and educating neutrophils to promote tumor progression. IL-17A might therefore serve as a potent prognostic factor in TNBC.

An induction of microRNA, miR-7 through estrogen treatment in breast carcinoma.

BACKGROUND: Estrogen plays an important role in the development of estrogen-dependent breast carcinoma. Recently, several studies demonstrated a possible involvement of several micro RNAs (miRNAs) in the development of resistance to endocrine therapy in breast cancer patients, but the correlation between estrogen actions and miRNA expression in breast carcinoma still remains largely unknown. Therefore, in this study, we examined the in vitro effects of estrogen upon miRNA expression profiles in breast carcinoma. METHODS: We first screened the miRNA expression profiles induced by 17ß-Estradiol (E2) using RT2 miRNA PCR Array in the ER-positive breast carcinoma cell line MCF-7. We identified miR-7 as the important miRNA associated with estrogen actions in these cells and further examined the changes of estrogen-dependent EGFR expression by miR-7 in ER-positive or -negative breast carcinoma cell lines including MCF-7. We also evaluated the correlation between miR-7 and EGFR expression in breast carcinoma cells derived from 21 patients using laser capture microdissection combined with quantitative reverse transcriptase-PCR. RESULTS: Seventeen miRNAs were significantly induced by E2 treatment in the MCF-7 cell line. Among 17 miRNAs induced by estradiol treatment, only miR-7 expression was significantly decreased by subsequent ICI treatment. The expression of miR-7 was up-regulated 2.94-fold by E2 treatment. miR-7 was reported to suppress epidermal growth factor receptor (EGFR) expression in several human malignancies. Transfection of miR-7 significantly suppressed EGFR mRNA levels in MCF-7 cells. Depletion of E2 from cell culture media also increased the expression level of EGFR mRNA in MCF-7 and T-47D cells but not in ER-negative, MDA-MB-231 and SK-BR-3 cells. We also evaluated the status of miR-7 in breast carcinoma tissues, but the correlation between the status of miR-7 and EGFR in carcinoma cells isolated by laser capture microscopy was not detected. CONCLUSIONS: These results suggest that miR-7 may play a role in the development of resistance to endocrine therapy in breast cancer patients through regulating EGFR expression of carcinoma cells.

Nudix-type motif 2 in human breast carcinoma: a potent prognostic factor associated with cell proliferation.

Nudix-type motif 2 (NUDT2) hydrolyzes diadenosine 5',5'''-p1,p4-tetraphosphate (Ap4A) associated with various cellular functions. Previous studies demonstrated its regulation through estrogens, suggesting possible importance of NUDT2 in breast carcinoma. NUDT2, however, has not been examined in malignant tissues. Therefore, we examined its expression and functions in breast carcinoma. Immunohistochemistry for NUDT2 was examined by invasive ductal carcinoma (IDC: n = 145) and pure ductal carcinoma in situ (DCIS: n = 82), and NUDT2 mRNA was examined by real-time PCR in 9 DCIS, 19 IDC and 6 non-neoplastic breast tissues. We also used T47D breast carcinoma cells in in vitro studies. NUDT2 immunoreactivity was detected in 78% of DCIS and 63% of IDC, and NUDT2 mRNA level was significantly higher in DCIS or IDC than non-neoplastic breast. NUDT2 status was significantly correlated with Van Nuys classification, HER2 or Ki-67 in DCIS, and with stage, lymph node metastasis, histological grade or HER2 in IDC. NUDT2 status was significantly associated with adverse clinical outcome of IDC patients and proved an independent prognostic factor. Results of transfection experiments demonstrated that proliferation activity of T47D cells was significantly associated with NUDT2 expression level according to the treatment of estradiol and/or tamoxifen. NUDT2 expression was significantly decreased by estradiol, and it was also significantly decreased in T47D cells transfected with HER2 siRNA. These findings suggest that NUDT2 is an estrogen-repressed gene and is also induced by HER2 pathways in breast carcinoma cells. NUDT2 promotes proliferation of breast carcinoma cells and is a potent prognostic factor in human breast carcinomas.

Immunolocalization of estrogen-producing and metabolizing enzymes in benign breast disease: comparison with normal breast and breast carcinoma.

It is well known that estrogens play important roles in the cell proliferation of breast carcinoma. Benign breast disease (BBD) contains a wide spectrum of diseases, and some are considered an important risk factor for subsequent breast carcinoma development. However, the significance of estrogens in BBD has remained largely unknown. Therefore, in this study, we examined tissue concentrations of estrogens and immunolocalization of estrogen-producing/metabolizing enzymes in BBD, and compared these findings with those in the normal breast and ductal carcinoma in situ (DCIS). Tissue concentration of estradiol in BBD (n = 9) was significantly (3.4-fold) higher than normal breast (n = 9) and nearly the same (0.7-fold) as in DCIS (n = 9). Immunoreactivity of estrogen sulfotransferase in BBD was significantly lower (n = 82) than normal breast (n = 28) but was not significantly different from DCIS (n = 28). Aromatase and steroid sulfatase immunoreactivities tended to be higher (P = 0.07) in BBD than in normal breast, and 17ß-hydroxysteroid dehydrogenase type 1 immunoreactivity was significantly higher in BBD than normal breast in the postmenopausal tissues. Immunoreactivity of estrogen and progesterone receptors was also significantly higher in BBD than normal breast. These results suggest that tissue concentration of estradiol is increased in BBD at a level similar to DCIS, which is considered mainly due to loss of estrogen sulfotransferase expression. Increased local estradiol concentration in BBD due to aberrant expression of estrogen-producing/metabolizing enzymes may play important roles in the accumulation of estradiol-mediated growth and/or subsequent development of breast carcinoma.

Vasohibin-1 as a potential predictor of aggressive behavior of ductal carcinoma in situ of the breast.

Vasohibin-1 is a recently identified negative feedback regulator of angiogenesis induced by VEGF-A and bFGF. In this study, we first evaluated mRNA expression of vasohibin-1 and CD31 in 39 Japanese female breast carcinoma specimens including 22 invasive ductal carcinoma (IDC) and 17 ductal carcinoma in situ (DCIS) using a real-time quantitative RT-PCR (QRT-PCR) with LightCycler system. In addition, we also immunolocalized vasohibin-1 and CD31 and compared their immunoreactivity to nuclear grades and histological grades of 100 carcinoma cases (50 IDC and 50 DCIS). There were no statistically significant differences of CD31 mRNA expression and the number of CD31 positive vessels between DCIS and IDC (P = 0.250 and P = 0.191, respectively), whereas there was a statistically significant difference in vasohibin-1 mRNA expression and the number of vasohibin-1 positive vessels in DCIS and IDC (P = 0.022 and P < or = 0.001, respectively). There was a significant positive correlation between vasohibin-1 mRNA level and Ki-67 labeling index in DCIS (r(2) = 0.293, P < or = 0.001). In addition, vasohibin-1 mRNA expression was correlated with high nuclear and histological grades in DCIS cases and a significant positive correlation was detected between the number of vasohibin-1 positive vessels and Ki-67 labeling index or nuclear grade or Van Nuys classification of carcinoma cells (P < or = 0.001, respectively). These results all indicate the possible correlation between aggressive biological features in DCIS including increased tumor cell proliferation and the status of neovascularization determined by vasohibin-1 immunoreactivity.

Androgens in human breast carcinoma.

Sex steroids play important roles in the development of human breast carcinoma. Androgen receptor (AR) is expressed in a majority of breast carcinoma tissues. However, the significance of androgen actions remains largely unclear in breast carcinoma, differing from estrogen actions. Therefore, in this review, we summarized recent studies on androgens in breast carcinoma. Concentration of a potent androgen, 5alpha-dihydrotestosterone (DHT), was significantly higher in breast carcinoma tissue than in plasma, and DHT is considered to be locally produced from circulating androstenedione by 17beta-hydroxysteroid dehydrogenase type 5 and 5alpha-reductase. On the other hand, aromatase was recently reported as a negative regulator for intratumoral DHT production by possibly reducing the precursor testosterone. Androgens predominantly show antiproliferative effects in breast carcinoma cells, but association between AR status and the clinical outcome of the patient remains controversial, perhaps partly because AR status does not necessarily reflect androgenic action in breast carcinoma. Recently, molecular apocrine breast carcinoma was identified by microarray analysis. Molecular apocrine carcinoma was characterized by being estrogen receptor (ER) negative and AR positive and by being associated with increased androgen signaling and apocrine features. Therefore, androgenic actions may also be involved in apocrine features in breast carcinoma.

Molecular morphological approach to the pathological study of development and advancement of human breast cancer.

Since the concept of gene profile-based intrinsic subtypes was proposed, various studies on pathological characteristics have been performed. Particularly, triplenegative (TN) breast cancer, which is negative for all hormone receptors [estrogen receptor (ER) and/or progesterone receptor (PgR) and human epidermal growth factor 2 (HER2)], has been attracting attention because effects of endocrine and targeting therapies cannot be anticipated and thus selecting a treatment method is difficult. TN cancer accounts for about 10%-15% of all invasive breast cancer cases in Japanese, which is significantly lower than the incidence reported in the United States. Cytokeratin (CK) 5/6 or epidermal growth factor receptor (EGFR) is positive in 80%, being classified as basal-like carcinoma, but it should be understood that TN breast cancer and basal-like carcinoma are not necessarily the same. Criteria for positivity judgment of ER, PgR, and HER2 were established to select treatment in cases positive for each marker, and greater importance is attached to strict accuracy control. Inversely, the level of negative findings to judge TN varies among the judgment criteria. In any case, the prognosis of TN breast cancer is poor. Pathologically, TN breast cancer shows certain morphological characteristics, such as high grade and a pushing margin, and abnormalities of BRCA1 and p53 are frequently noted. At present, as no effective therapeutic strategy has been established for TN breast cancer, further clarification of the molecular biological characteristics of such cancers is needed. In addition, the incidence of TN-type ductal carcinoma in situ (DCIS) is low, suggesting that TN does not remain preinvasive DCIS for a prolonged period and that it transforms to invasive cancer in an early stage. Because mammary gland basal cells have characters of progenitor or stem cells that differentiate into both luminal epithelium and myoepithelial cells, these cells may be utilized for the differential diagnosis of the benignity or malignancy of intraductal lesions in routine pathological practice. As proliferation markers, such as Ki-67, and multiple gene arrays for gene signature are also utilized to select adjuvant therapy, analysis may progress further in the future.