Neuroendocrine Breast Carcinomas Share Prognostic Factors with Gastroenteropancreatic Neuroendocrine Tumors: A Putative Prognostic Role of Menin, p27, and SSTR-2A.

OBJECTIVES: Due to the rarity of breast carcinomas with neuroendocrine features (NEBC), the knowledge on their biology is very limited but the identification of their biology and prognostic factors is essential to evaluate both pathogenesis and possible targeted treatment options. We assessed the expression of the well-characterized prognostic factors of gastroenteropancreatic neuroendocrine tumors (GEP-NET) in NEBC. METHODS: We assessed the immunohistochemical expression of neuron-specific enolase (NSE), thymidylate synthase (TS), p27, CD56, menin, and somatostatin receptor type 2A (SSTR-2A) in a series of 36 NEBC and 45 invasive ductal carcinomas (IDC). RESULTS: Nuclear and cytoplasmic TS, nuclear and cytoplasmic NSE, and nuclear p27 had significant overexpression in NEBC compared with IDC (for all, p < 0.01). In NEBC, cytoplasmic SSTR-2A expression was associated with excellent distant disease-free survival (p = 0.013), cytoplasmic menin expression with poorer relapse-free survival (p = 0.022), and nuclear p27 with longer breast cancer-specific survival (p = 0.022). CONCLUSIONS: There is a striking similarity in GEP-NET and NEBC regarding prognostic factors. GEP-NET and NEBC also appear to show similar expression patterns of the studied markers, while there are notable differences compared to IDC. Due to the wide expression of SSTR-2A, the treatment option with somatostatin analogs in NEBC should be evaluated.

Targeted Next-Generation Sequencing Identifies a Recurrent Mutation in MCPH1 Associating with Hereditary Breast Cancer Susceptibility.

Breast cancer is strongly influenced by hereditary risk factors, a majority of which still remain unknown. Here, we performed a targeted next-generation sequencing of 796 genes implicated in DNA repair in 189 Finnish breast cancer cases with indication of hereditary disease susceptibility and focused the analysis on protein truncating mutations. A recurrent heterozygous mutation (c.904_916del, p.Arg304ValfsTer3) was identified in early DNA damage response gene, MCPH1, significantly associating with breast cancer susceptibility both in familial (5/145, 3.4%, P = 0.003, OR 8.3) and unselected cases (16/1150, 1.4%, P = 0.016, OR 3.3). A total of 21 mutation positive families were identified, of which one-third exhibited also brain tumors and/or sarcomas (P = 0.0007). Mutation carriers exhibited significant increase in genomic instability assessed by cytogenetic analysis for spontaneous chromosomal rearrangements in peripheral blood lymphocytes (P = 0.0007), suggesting an effect for MCPH1 haploinsufficiency on cancer susceptibility. Furthermore, 40% of the mutation carrier tumors exhibited loss of the wild-type allele. These findings collectively provide strong evidence for MCHP1 being a novel breast cancer susceptibility gene, which warrants further investigations in other populations.

Rare missense mutations in RECQL and POLG associate with inherited predisposition to breast cancer.

Several known breast cancer susceptibility genes with moderate-to-high risk alleles encode proteins involved in DNA damage response (DDR). As these explain less than half of the hereditary breast cancer cases, additional predisposing alleles are likely to be discovered. Many of the previous studies utilizing massive parallel sequencing have focused on the protein-truncating variants, and the role of rare missense mutations has remained poorly addressed. To identify novel susceptibility factors, we have systematically analyzed the data from our parallel sequencing of 796 DDR genes in 189 Northern Finnish hereditary breast cancer patients for rare missense variants, predicted as deleterious. Thirty-five variants were studied here for the disease association using Finnish breast cancer case (n = 492-2,035) and control (n = 277-1,539) cohorts. As a result, two missense variants in genes involved in DNA replication, RECQL p.I156M and POLG p.L392V, the former involving genomic and the latter mitochondrial DNA replication, showed significant association with risk of breast cancer. Rare RECQL p.I156M allele was observed in breast cancer cases only (6/1,946, 0.3%, p = 0.043), whereas POLG p.L392V was two times more frequent in breast cancer cases (53/2,238, 2.4%) compared to controls (18/1,539, 1.2%, OR = 2.1, 95% CI 1.2-3.5, p = 0.010). Based on the current genetic data, both RECQL p.I156M and POLG p.L392V represent novel breast cancer predisposing alleles.

Long-term cardiovascular morbidity and mortality in patients treated for differentiated thyroid cancer.

OBJECTIVES: Thyroid hormone suppression therapy has been widely used in the treatment of thyroid cancer, but concerns have been raised about the cardiovascular risks of this treatment. The objective of this study was to evaluate long-term cardiovascular morbidity and mortality in patients treated for differentiated thyroid cancer (DTC) and to assess the effect of TSH suppression and radioiodine (RAI) treatment on the cardiovascular outcome. DESIGN: Retrospective cohort study. PATIENTS AND MEASUREMENTS: Patients (n = 901) treated for DTC between 1981 and 2002 at 2 Finnish University hospitals were compared with a randomly chosen reference group (n = 4485) matched for age, gender and the place of residence. Kaplan-Meier and Cox regression analyses were used to estimate the risk of morbidity or death due to different cardiovascular diseases (CVD) after the diagnosis of DTC. RESULTS: Morbidity due to any CVD (hazard ratio [HR] 1.16, 95% confidence interval [CI] 1.05-1.28) and due to all arrhythmias (HR 1.25, CI 1.06-1.48) and atrial fibrillation (AF) (HR 1.29, CI 1.06-1.57) was more frequent in the DTC patients than in the controls. The increased cardiovascular morbidity was confined to patients with a mean TSH level below 0.1 mU/L (HR 1.27, CI 1.03-1.58) and to those treated with RAI (HR 1.18, CI 1.05-1.31). Cardiovascular mortality, however, was lower among the patients than the controls (HR 0.73, CI 0.58-0.92), due to a lower mortality from coronary artery disease. CONCLUSIONS: Differentiated thyroid cancer patients have an increased CVD morbidity, which is mostly accountable to AF and to TSH suppression below 0.1 mU/L.

High-level cytoplasmic claudin 3 expression is an independent predictor of poor survival in triple-negative breast cancer.

BACKGROUND: The subtype of claudin-low breast cancer can be reliably determined only by gene-expression profiling. Attempts have been made to develop immunohistochemical surrogates, which nearly always focus on membranous claudin expression. METHODS: We assessed the immunohistochemical expression of both membranous and cytoplasmic claudins 3, 4 and 7 in a series of 197 non-metastatic breast cancers, enriched with triple-negative breast cancers (TNBCs; 60%). The expression of epithelial-to-mesenchymal transition-regulating transcription factors Sip1, Zeb1 and vimentin had previously been determined in the same material. RESULTS: In multivariate analysis, strong cytoplasmic claudin 3 expression was associated with poor relapse-free survival (RFS), disease-free survival, distant disease-free survival, breast cancer-specific survival and overall survival among TNBC patients (for RFS, RR 5.202, 95% CI 1.210-22.369, p = 0.027, vs. T-class, RR 0.663, 95% CI 0.168-2.623, p = 0.558, and N-class, RR 3.940, 95% CI 0.933-16.631, p = 0.062). Cytoplasmic claudin 3 expression was also associated with strong nuclear Sip1 expression (p = 0.000053), TNBC phenotype (p = 0.012) and within them, non-basal-like phenotype (p = 0.026). Cytoplasmic claudin 7 was associated with dismal RFS (RR 6.328, 95% CI 1.401-28.593, p = 0.016, vs. T-class, RR 0.692, 95% CI 0.242-1.982, p = 0.493, and N-class, RR 2.981, 95% CI 1.1016-8.749, p = 0.047). Low cytoplasmic expression of claudins 3, 4 and 7 together also predicted poor RFS (RR 6.070, 95% CI 1.347-27.363, p = 0.019, vs. T-class, RR 0.677, 95% CI 0.237-1.934, p = 0.467, and N-class, RR 3.167, 95% CI 1.079-9.290, p = 0.036). CONCLUSIONS: Immunohistochemical expression levels of cytoplasmic claudins 3 and 7 appear to be novel prognostic factors in TNBC.

Primary neuroendocrine breast carcinomas are associated with poor local control despite favourable biological profile: a retrospective clinical study.

BACKGROUND: Breast carcinomas with neuroendocrine features (NEBC) are a very rare entity of mammary neoplasms, WHO classification of which has recently been revised. There are very limited data available about the clinical behaviour and treatment options of NEBC. METHODS: We collected retrospectively patients with NEBC from Oulu and Helsinki University Hospitals in 2007-2015. There were 43 NEBC cases during the period. RESULTS: The incidence of NEBC from all breast cancers varied from 0.1% in Helsinki to 1.3% in Oulu. The mean tumor size was 2.2 cm and 23 patients (55.8%) had no lymph node metastases when diagnosed. In total, 4 patients (9.3%) had distant metastases at the time of diagnosis. High estrogen receptor (ER) expression was observed in 41 (97.7%) patients. When non-metastatic NEBC were compared to a prospective set of ductal carcinomas (n = 506), NEBC were more often HER2 negative (p = 0.046), ER positive (p = 0.0062) and the NEBC patients were older (p < 0.0005) than patients with ductal carcinomas. Plasma chromogranin A correlated only to higher age at diagnosis (p = 0.0028). Relapse-free survival (p = 0.0013), disease-free survival (p = 0.024) and overall survival (p = 0.0028) favoured ductal carcinomas compared to NEBC, while no difference was observed in distant disease-free survival or in breast cancer-specific survival. CONCLUSIONS: There is remarkable variation in the incidence of NEBC in Finland, which is likely to be explained by differences in the use of neuroendocrine marker immunostainings. Poor local control and worse overall survival may be linked to the more aggressive biology of the disease, despite its association with apparently indolent prognostic factors.

CHEK2 c.1100delC mutation is associated with an increased risk for male breast cancer in Finnish patient population.

BACKGROUND: Several susceptibility genes have been established for female breast cancer, of which mutations in BRCA1 and especially in BRCA2 are also known risk factors for male breast cancer (MBC). The role of other breast cancer genes in MBC is less well understood. METHODS: In this study, we have genotyped 68 MBC patients for the known breast or ovarian cancer associated mutations in the Finnish population in CHEK2, PALB2, RAD51C, RAD51D, and FANCM genes. RESULTS: CHEK2 c.1100delC mutation was found in 4 patients (5.9%), which is significantly more frequent than in the control population (OR: 4.47, 95% CI 1.51-13.18, p = 0.019). Four CHEK2 I157T variants were also detected, but the frequency did not significantly differ from population controls (p = 0.781). No RAD51C, RAD51D, PALB2, or FANCM mutations were found. CONCLUSIONS: These data suggest that the CHEK2 c.1100delC mutation is associated with an increased risk for MBC in the Finnish population.

Telomeric G-quadruplex-forming DNA fragments induce TLR9-mediated and LL-37-regulated invasion in breast cancer cells in vitro.

Toll-like receptor 9 (TLR9) is a cellular DNA-receptor widely expressed in cancers. We previously showed that synthetic and self-derived DNA fragments induce TLR9-mediated breast cancer cell invasion in vitro. We investigated here the invasive effects of two nuclease-resistant DNA fragments, a 9-mer hairpin, and a G-quadruplex DNA based on the human telomere sequence, both having native phosphodiester backbone. Cellular uptake of DNAs was investigated with immunofluorescence, invasion was studied with Matrigel-assays, and mRNA and protein expression were studied with qPCR and Western blotting and protease activity with zymograms. TLR9 expression was suppressed through siRNA. Although both DNAs induced TLR9-mediated changes in pro-invasive mRNA expression, only the telomeric G-quadruplex DNA significantly increased cellular invasion. This was inhibited with GM6001 and aprotinin, suggesting MMP- and serine protease mediation. Furthermore, complexing with LL-37, a cathelicidin-peptide present in breast cancers, increased 9-mer hairpin and G-quadruplex DNA uptake into the cancer cells. However, DNA/LL-37 complexes decreased invasion, as compared with DNA-treatment alone. Invasion studies were conducted also with DNA fragments isolated from neoadjuvant chemotherapy-treated breast tumors. Also such DNA induced breast cancer cell invasion in vitro. As with the synthetic DNAs, this invasive effect was reduced by complexing the neoadjuvant tumor-derived DNAs with LL-37. We conclude that 9-mer hairpin and G-quadruplex DNA fragments are nuclease-resistant DNA structures that can act as invasion-inducing TLR9 ligands. Their cellular uptake and the invasive effects are regulated via LL-37. Although such structures may be present in chemotherapy-treated tumors, the clinical significance of this finding requires further studying.

Current follow-up of a breast cancer patient.

The number of patients with breast cancer is on the rise, which leads to an increasing number of patients in need of follow-up and support for recovery from treatments. The disease will recur in one out of five patients. With the exception of imaging of the breasts carried out at intervals of 1 to 2 years, frequent appointments or imaging have not been shown to be beneficial for the prognosis. Follow-up care of breast cancer is well suited to be carried out by the nursing staff. The status of mobile applications developed for patient monitoring as part of the surveillance is becoming more clear.

Rare copy number variants observed in hereditary breast cancer cases disrupt genes in estrogen signaling and TP53 tumor suppression network.

Breast cancer is the most common cancer in women in developed countries, and the contribution of genetic susceptibility to breast cancer development has been well-recognized. However, a great proportion of these hereditary predisposing factors still remain unidentified. To examine the contribution of rare copy number variants (CNVs) in breast cancer predisposition, high-resolution genome-wide scans were performed on genomic DNA of 103 BRCA1, BRCA2, and PALB2 mutation negative familial breast cancer cases and 128 geographically matched healthy female controls; for replication an independent cohort of 75 similarly mutation negative young breast cancer patients was used. All observed rare variants were confirmed by independent methods. The studied breast cancer cases showed a consistent increase in the frequency of rare CNVs when compared to controls. Furthermore, the biological networks of the disrupted genes differed between the two groups. In familial cases the observed mutations disrupted genes, which were significantly overrepresented in cellular functions related to maintenance of genomic integrity, including DNA double-strand break repair (P = 0.0211). Biological network analysis in the two independent breast cancer cohorts showed that the disrupted genes were closely related to estrogen signaling and TP53 centered tumor suppressor network. These results suggest that rare CNVs represent an alternative source of genetic variation influencing hereditary risk for breast cancer.

Recurrent CYP2C19 deletion allele is associated with triple-negative breast cancer.

BACKGROUND: Using a genome-wide approach, we have previously observed an increase in the frequency of rare copy number variants (CNVs) in familial and early-onset breast cancer cases when compared to controls. Moreover, the biological networks of the CNV disrupted genes differed between the two groups. Here, six of the previously observed CNVs were selected for further investigation. Four of these were singletons and disturbed the following genes: DCLRE1C, CASP3, DAB2IP and ITGA9, encoding proteins that are part of the TP53 and ß-estradiol centered network. The two others were recurrent alleles and disrupted CDH19 and CYP2C19 genes. Of these, CDH19 encodes a cadherin functioning as a cell-cell adhesion receptor and CYP2C19 a CYP450 enzyme with a major function in estrogen catabolism. METHODS: The exact breakpoints of the six previously observed CNV deletion alleles were defined by using qPCR, nested PCR and sequencing. The prevalence of these CNVs was investigated in 842 Northern Finnish breast cancer cases, unselected for family history of cancer and age at disease onset, as well as in 497 healthy female controls by using multiplex PCR. Also the association of the relatively common CDH19 and CYP2C19 deletion alleles with different clinical parameters was studied. RESULTS: No significant differences in the carrier frequencies between cases and controls were found for any of the studied CNVs. However, the deletion in CYP2C19 showed a significant association with triple-negative breast cancer (p=0.021). CONCLUSION: Our results indicate that inherited changes in CYP2C19 gene participating in estrogen catabolism have an influence on the molecular subtype of breast cancer.

Outcome of patients with HER2-positive breast cancer treated with or without adjuvant trastuzumab in the Finland Capecitabine Trial (FinXX).

BACKGROUND: Little information is available about survival outcomes of patients with HER2-positive early breast cancer treated with adjuvant capecitabine-containing chemotherapy with or without trastuzumab. PATIENTS AND METHODS: One thousand and five hundred patients with early breast cancer were entered to the Finland Capecitabine trial (FinXX) between January 2004 and May 2007, and were randomly assigned to receive either three cycles of adjuvant TX (docetaxel, capecitabine) followed by three cycles of CEX (cyclophosphamide, epirubicin, capecitabine; TX-CEX) or three cycles of docetaxel followed by three cycles of CEF (cyclophosphamide, epirubicin, fluorouracil; T-CEF). The primary endpoint was recurrence-free survival (RFS). The study protocol was amended in May 2005 while study accrual was ongoing to allow adjuvant trastuzumab for patients with HER2-positive cancer. Of the 284 patients with HER2-positive cancer accrued to FinXX, 176 (62.0%) received trastuzumab after amending the study protocol, 131 for 12 months and 45 for nine weeks. The median follow-up time was 6.7 years. RESULTS: Patients with HER2-positive cancer who received trastuzumab had better RFS than those who did not (five-year RFS 89.2% vs. 75.9%; HR 0.41, 95% CI 0.23-0.72; p = 0.001). Patients treated with trastuzumab for 12 months or nine weeks had similar RFS. There was no significant interaction between trastuzumab administration and the type of chemotherapy. Four (2.3%) patients treated with trastuzumab had heart failure or left ventricular dysfunction, three of these received capecitabine. CONCLUSION: Adjuvant trastuzumab improves RFS of patients treated with TX-CEX or T-CEF. Few patients had cardiac failure.

The prognostic significance and value of cyclin D1, CDK4 and p16 in human breast cancer.

INTRODUCTION: Loss of the retinoblastoma protein tumor suppressor gene (RB) coding for a nuclear phosphoprotein that regulates the cell cycle is found in many human cancers and probably leads to disruption of the p16-cyclin D1-CDK4/6-RB pathway. Cyclin D1 is known to activate CDK4, which then phosphorylates the RB protein, leading to cell cycle progression. p16 inhibits CDK4, keeping RB hypophosphorylated and preventing cell cycle progression. The significance of these three markers, cyclin D1, CDK4 and p16, for breast cancer and carcinogenesis is nevertheless still controversial. METHODS: The material consisted of 102 formalin-fixed human breast cancer samples, in which cyclin D1, CDK4 and p16 expression was evaluated immunohistochemically. The amounts of cyclin D1 mRNA present were analyzed by quantitative real time PCR. RESULTS: High cyclin D1 expression statistically significantly correlated with lower tumor grade, estrogen and progesterone receptor positivity and lower proliferation activity in breast tumors and increased breast cancer-specific survival and overall survival. Tumors with high cyclin D1 protein had 1.8 times higher expression of cyclin D1 mRNA. CDK4 expression did not correlate with cyclin D1 expression or the survival data. p16 expression was associated with Human Epidermal Growth Factor Receptor 2 (HER2) negativity and increased breast cancer-specific survival and disease-free survival. No statistical correlations between cyclin D1, CDK4 and p16 were found. CONCLUSIONS: Cyclin D1 was associated with a good breast cancer prognosis but functioned independently of CDK4. High cyclin D1 expression may be partially due to increased CCND1 transcription. p16 correlated with a better prognosis and may function without CDK4. In conclusion, it appears that cyclin D1, CDK4 and p16 function independently in human breast cancer.

Vimentin, zeb1 and Sip1 are up-regulated in triple-negative and basal-like breast cancers: association with an aggressive tumour phenotype.

In epithelial-to-mesenchymal transition (EMT) epithelial cancer cells achieve mesenchymal features, essentially helping them to metastasize. There is some evidence that EMT could be increased in triple-negative (TNBC) or basal-like breast cancers, although more precise mechanisms considering e.g. EMT-regulating transcription factors are largely unknown. We assessed immunohistochemically vimentin (separately in in situ areas and in invasive cells) as an indicator of EMT, and also EMT-regulating transcription factors zeb1 (separately in stroma and tumour) and Sip1 (in nuclei and cytoplasm) in histological samples of 231 women with local or locally advanced invasive breast cancer. 51.1 % of patients had TNBC and 48.9 % oestrogen and progesterone receptor-positive and HER2 negative breast cancer. Basal-like breast cancers were defined as TNBC that also expressed epidermal growth factor receptor EGFR and/or cytokeratin 5/6. Vimentin expression in invasive cells was higher in TNBCs (p = 9 × 10(-12)) compared to non-TNBC tumours. Vimentin (p = 2 × 10(-6)), nuclear Sip1 (p = 0.035) and zeb1 in stroma (p = 0.013) were overexpressed in basal-like cancers compared to non-basal-like TNBCs. In non-TNBC group findings between studied markers and clinicopathological factors were rare. However, in TNBC cases, vimentin expression in invasive cells associated with poor differentiation (p = 0.00007), zeb1 expression in cancer cells with higher grade (p = 0.002), vascular invasion (p = 0.036) and larger T-class (p = 0.027), whereas stromal zeb1 associated with lymphatic vessel invasion (p = 0.036) and vascular invasion (p = 0.039). High nuclear Sip1 expression was prognostic for poor disease-free survival (p = 0.002) in the whole cohort. The current results emphasize the increased role of EMT in TNBC and especially in basal-like breast cancers. These observations also support the role of studied parameters in tumour progression.

A recurrent mutation in PALB2 in Finnish cancer families.

BRCA1, BRCA2 and other known susceptibility genes account for less than half of the detectable hereditary predisposition to breast cancer. Other relevant genes therefore remain to be discovered. Recently a new BRCA2-binding protein, PALB2, was identified. The BRCA2-PALB2 interaction is crucial for certain key BRCA2 DNA damage response functions as well as its tumour suppression activity. Here we show, by screening for PALB2 mutations in Finland that a frameshift mutation, c.1592delT, is present at significantly elevated frequency in familial breast cancer cases compared with ancestry-matched population controls. The truncated PALB2 protein caused by this mutation retained little BRCA2-binding capacity and was deficient in homologous recombination and crosslink repair. Further screening of c.1592delT in unselected breast cancer individuals revealed a roughly fourfold enrichment of this mutation in patients compared with controls. Most of the mutation-positive unselected cases had a familial pattern of disease development. In addition, one multigenerational prostate cancer family that segregated the c.1592delT truncation allele was observed. These results indicate that PALB2 is a breast cancer susceptibility gene that, in a suitably mutant form, may also contribute to familial prostate cancer development.

11q13 is a susceptibility locus for hormone receptor positive breast cancer.

A recent two-stage genome-wide association study (GWAS) identified five novel breast cancer susceptibility loci on chromosomes 9, 10, and 11. To provide more reliable estimates of the relative risk associated with these loci and investigate possible heterogeneity by subtype of breast cancer, we genotyped the variants rs2380205, rs1011970, rs704010, rs614367, and rs10995190 in 39 studies from the Breast Cancer Association Consortium (BCAC), involving 49,608 cases and 48,772 controls of predominantly European ancestry. Four of the variants showed clear evidence of association (P ≤ 3 × 10(-9) ) and weak evidence was observed for rs2380205 (P = 0.06). The strongest evidence was obtained for rs614367, located on 11q13 (per-allele odds ratio 1.21, P = 4 × 10(-39) ). The association for rs614367 was specific to estrogen receptor (ER)-positive disease and strongest for ER plus progesterone receptor (PR)-positive breast cancer, whereas the associations for the other three loci did not differ by tumor subtype.

Expressions of individual PHDs associate with good prognostic factors and increased proliferation in breast cancer patients.

Tumor hypoxia-inducible transcription factor (HIF) overexpression often associates with a poor prognosis. Stability of the HIF-α subunits is regulated by HIF prolyl 4-hydroxylases, PHD1-3. We assessed here immunohistochemical expression of PHD1-3 and HIF-1α and 2α in patients with invasive ductal breast carcinoma (n = 102) and correlated their expression levels with main clinical prognostic factors and survival. PHD1 expression correlated with high proliferation, and these tumors were mainly estrogen receptor-negative. PHD3 expression declined in tumors of large size, poor differentiation, and high proliferation. There was a tendency for increased breast cancer-specific survival and longer disease-free survival among patients with high tumor PHD2 expression. Surprisingly, PHD1-3 expression did not correlate with HIF-1α or HIF-2α downregulation. However, HIF-2α expression correlated independently with low tumor stage and HIF-1α expression had a tendency for decreased breast cancer-specific survival. PHD1 and 3 appear to be HIF-independent factors in breast cancer. Not all PHD1 associated proliferation is estrogen-dependent and it is associated with a poor prognosis of cancer. PHD3 may be an important regulator of apoptosis and it is mainly found in tumors with good prognosis. PHD2 expression is likely to be involved in increased survival.

Estrogen receptor-α and sex steroid hormones regulate Toll-like receptor-9 expression and invasive function in human breast cancer cells.

Toll-like receptor 9 (TLR9) is a cellular DNA-receptor, which is widely expressed in cancer. Synthetic TLR9-ligands induce cancer cell invasion in vitro, but the role of TLR9 in cancer pathophysiology remains unclear. Increased TLR9 expression has been, however, detected in estrogen receptor negative (ER-) breast cancers. In this study, we investigated the effects of ERα expression and sex steroid hormones on TLR9 expression in human ER+ (MCF-7, T47-D) and ER- (MDA-MB-231) breast cancer cell lines in vitro. We also studied TLR9 mRNA expression in archival breast cancer specimens (n = 12) with qRT-PCR, using primer sets that detect only the TLR9A isoform or the isoforms A and B (TLR9A/B). The TLR9 mRNA expression was detected in 10/12 specimens with both primer sets, and in 1/12 with only the TLR9A or the TLR9A/B primer sets. The basal TLR9 mRNA expression levels were significantly lower in the ER+ cell lines as compared with the ER- MDA-MB-231 cells. The transfection of ERα cDNA into MDA-MB-231 cells also resulted in down-regulation of TLR9 expression. While sex steroids had no effect on TLR9 expression in MCF-7 cells, testosterone (10(-8) M) induced TLR9 expression in MDA-MB-231 and T47-D cells. Although bicalutamide blocked this testosterone effect in MDA-MB-231 cells, in T47-D cells bicalutamide increased TLR9 expression and only partially blocked the testosterone effects. Estradiol (10(-8) M) induced TLR9 expression in T47-D cells. The invasive effects of synthetic TLR9-ligands were augmented by testosterone in vitro. This effect was lost in TLR9 siRNA MDA-MB-231 cells and also decreased by over-expression of ERα, which also inhibited NF-κB activation by TLR9-ligands. In conclusion, expression of TLR9 isoforms A and B can be detected in clinical breast cancer specimens. The ERα and sex steroid hormones regulate TLR9 expression and invasive effects in the breast cancer cells. Also, the commonly used hormonal cancer therapy bicalutamide affects TLR9 expression.

Low TLR9 expression defines an aggressive subtype of triple-negative breast cancer.

Toll-like receptor-9 (TLR9) is a DNA receptor widely expressed in cancers. Although synthetic TLR9 ligands induce cancer cell invasion in vitro, the role of TLR9 in cancer pathophysiology is unclear. We discovered that low tumor TLR9 expression is associated with significantly shortened disease-specific survival in patients with triple negative but not with ER+ breast cancers. A likely mechanism of this clinical finding involves differential responses to hypoxia. Our pre-clinical studies indicate that while TLR9 expression is hypoxia-regulated, low TLR9 expression has different effects on triple negative and ER+ breast cancer invasion in hypoxia. Hypoxia-induced invasion is augmented by TLR9 siRNA in triple negative, but not in ER+ breast cancer cells. This is possibly due to differential TLR9-regulated TIMP-3 expression, which remains detectable in ER+ cells but disappears from triple-negative TLR9 siRNA cells in hypoxia. Our results demonstrate a novel role for this innate immunity receptor in cancer biology and suggest that TLR9 expression may be a novel marker for triple-negative breast cancer patients who are at a high risk of relapse. Furthermore, these results suggest that interventions or events, which induce hypoxia or down-regulate TLR9 expression in triple-negative breast cancer cells may actually induce their spread.

Divergent behaviour of oxidative stress markers 8-hydroxydeoxyguanosine (8-OHdG) and 4-hydroxy-2-nonenal (HNE) in breast carcinogenesis.

AIMS: To clarify the role of oxidative stress during breast carcinogenesis by studying the expression of 8-hydroxydeoxyguanosine (8-OHdG) (a marker of oxidative DNA damage) and 4-hydroxy-2-nonenal (HNE) (a marker of lipid peroxidation) during the different phases of breast carcinogenesis. METHODS AND RESULTS: The study material consisted of a total of 219 patients: 31 with usual ductal hyperplasia (UDH), 25 with atypical ductal hyperplasia (ADH), 30 with ductal carcinoma in situ (DCIS) and 133 with invasive carcinoma. The expression of 8-OHdG and HNE were evaluated immunohistochemically. Both 8-OHdG (77.4%) and HNE (45.8%) expression was already seen in UDH lesions. Interestingly, the trend of these two immunostainings during breast carcinogenesis was diverse. 8-OHdG expression diminished significantly in invasive breast carcinomas compared to non-invasive lesions (P < 0.005 when set against non-invasive cohorts). Also within the same lesions, 8-OHdG expression was the most intensive in benign cells. Conversely, HNE immunostaining was strongest in invasive breast carcinomas (UDH versus invasive cohort, P = 0.015). CONCLUSIONS: 4-hydroxy-2-nonenal as a marker of lipid peroxidation increases during breast carcinogenesis, reflecting the role of oxidative stress in the pathogenesis of breast cancer. However, 8-OHdG shows diminished levels in carcinomas, possibly resulting from the induction of DNA repair in these invasive lesions.