Daniel Escuin

Taxane-Induced Blockade to Nuclear Accumulation of the Androgen Receptor Predicts Clinical Responses in Metastatic Prostate Cancer

Prostate cancer progression requires active androgen receptor (AR) signaling which occurs following translocation of AR from the cytoplasm to the nucleus. Chemotherapy with taxanes improves survival in patients with castrate resistant prostate cancer (CRPC). Taxanes induce microtubule stabilization, mitotic arrest, and apoptotic cell death, but recent data suggest that taxanes can also affect AR signaling. Here, we report that taxanes inhibit ligand-induced AR nuclear translocation and downstream transcriptional activation of AR target genes such as prostate-specific antigen. AR nuclear translocation was not inhibited in cells with acquired β-tubulin mutations that prevent taxane-induced microtubule stabilization, confirming a role for microtubules in AR trafficking. Upon ligand activation, AR associated with the minus-end-microtubule motor dynein, thereby trafficking on microtubules to translocate to the nucleus. Analysis of circulating tumor cells (CTC) isolated from the peripheral blood of CRPC patients receiving taxane chemotherapy revealed a significant correlation between AR cytoplasmic sequestration and clinical response to therapy. These results indicate that taxanes act in CRPC patients at least in part by inhibiting AR nuclear transport and signaling. Further, they suggest that monitoring AR subcellular localization in the CTCs of CRPC patients might predict clinical responses to taxane chemotherapy.

Increased signalling of EGFR and IGF1R, and deregulation of PTEN/PI3K/Akt pathway are related with trastuzumab resistance in HER2 breast carcinomas

Background:Trastuzumab resistance hampers its well-known efficacy to control HER2-positive breast cancer. The involvement of PI3K/Akt pathway in this mechanism is still not definitively confirmed.Methods:We selected 155 patients treated with trastuzumab after development of metastasis or as adjuvant/neoadjuvant therapy. We performed immunohistochemistry for HER2, ER/PR, epidermal growth factor 1-receptor (EGFR), α-insulin-like growth factor 1-receptor (IGF1R), phosphatase and tensin homologue (PTEN), p110α, pAkt, pBad, pmTOR, pMAPK, MUC1, Ki67, p53 and p27; mutational analysis of PIK3CA and PTEN, and PTEN promoter hypermethylation.Results:We found 46% ER/PR-positive tumours, overexpression of EGFR (15%), α-IGF1R (25%), p110α (19%), pAkt (28%), pBad (22%), pmTOR (23%), pMAPK (24%), MUC1 (80%), PTEN loss (20%), and PTEN promoter hypermethylation (20%). PIK3CA and PTEN mutations were detected in 17% and 26% tumours, respectively. Patients receiving adjuvant trastuzumab with α-IGF1R or pBad overexpressing tumours presented shorter progression-free survival (PFS) (all P⩽0.043). Also, p110α and mTOR overexpression, liver and brain relapses implied poor overall survival (OS) (all P⩽0.041). In patients with metastatic disease, decreased PFS correlated with p110α expression (P=0.024), whereas for OS were the presence of vascular invasion and EGFR expression (P⩽0.019; Cox analysis).Conclusion:Our results support that trastuzumab resistance mechanisms are related with deregulation of PTEN/PI3K/Akt/mTOR pathway, and/or EGFR and IGF1R overexpression in a subset of HER2-positive breast carcinomas.

Repression of E-cadherin by SNAIL, ZEB1, and TWIST in invasive ductal carcinomas of the breast: a cooperative effort?

It has been suggested that down-regulation of E-cadherin in invasive breast ductal carcinomas is mediated by the aberrant expression of several of its transcriptional repressors, but their inhibitory role and clinical importance are not yet well established. We investigated gene and protein expression patterns of the E-cadherin repressors SNAIL, ZEB1, and TWIST in relation to clinicopathologic parameters, in a series of 88 patients with invasive breast ductal carcinomas. Up-regulation of SNAIL messenger RNA (P = .008) and down-regulation of TWIST (P = .022) were associated with triple-negative tumors, whereas ZEB1 gene expression was more frequent in hormone-positive tumors (P = .004). Loss of E-cadherin was found in 19% of the tumors, but it did not correlate with aberrant expression of any of the repressors investigated herein. Nonetheless, we found that ZEB-1 protein overexpression inversely correlated with high tumor grade (P = .018), nuclear grade (P = .002), and presence of lymph nodes (P = .001), and these data were consistent with the gene expression data for ZEB1. Clinically, down-regulation of ZEB1 messenger RNA was associated with poor overall survival (P = .011) and disease-free survival (P = .053), whereas patients with TWIST negative tumors had a worse overall survival (P = .008) and disease-free survival (P = .006). Our data indicate that deregulation of TWIST is somehow important in the aggressiveness of triple-negative carcinomas and poor patient outcome, whereas down-regulation of ZEB1 seems to play a role in tumor spread, metastases, and poor survival.

Src, a potential target for overcoming trastuzumab resistance in HER2-positive breast carcinoma.

Background:Src is a non-receptor tyrosine kinase involved in signalling and crosstalk between growth-promoting pathways. We aim to investigate the relationship of active Src in response to trastuzumab of HER2-positive breast carcinomas.Methods:We selected 278 HER2-positive breast cancer patients with (n=154) and without (n=124) trastuzumab treatment. We performed immunohistochemistry on paraffin-embedded tissue microarrays of active Src and several proteins involved in the PI3K/Akt/mTOR pathway, PIK3CA mutational analysis and in vitro studies (SKBR3 and BT474 cancer cells). The results were correlated with clinicopathological factors and patients’ outcome.Results:Increased pSrc-Y416 was demonstrated in trastuzumab-resistant cells and in 37.8% of tumours that correlated positively with tumour size, necrosis, mitosis, metastasis to the central nervous system, p53 overexpression and MAPK activation but inversely with EGFR and p27. Univariate analyses showed an association of increased active Src with shorter survival in patients at early stage with HER2/hormone receptor-negative tumours treated with trastuzumab.Conclusions:Src activation participates in trastuzumab mechanisms of resistance and indicates poor prognosis, mainly in HER2/hormone receptor-negative breast cancer. Therefore, blocking this axis may be beneficial in those patients.

B-Tubulin Mutations Are Associated with Resistance to 2-Methoxyestradiol in MDA-MB-435 Cancer Cells

2-Methoxyestradiol is an estradiol metabolite with significant antiproliferative and antiangiogenic activity independent of estrogen receptor status. To identify a molecular basis for acquired 2-methoxyestradiol resistance, we generated a stable 2-methoxyestradiol-resistant (2ME2R) MDA-MB-435 human cancer cell line by stepwise exposure to increasing 2-methoxyestradiol concentrations. 2ME2R cells maintained in the presence of the drug and W435 cells maintained in the absence of the drug showed 32.34- to 40.07-fold resistance to 2-methoxyestradiol. Cross-resistance was observed to Vinca alkaloids, including vincristine, vinorelbine, and vinblastine (4.29- to 6.40-fold), but minimal resistance was seen to colchicine-binding agents including colchicine, colcemid, and AVE8062A (1.72- to 2.86-fold). No resistance was observed to paclitaxel and epothilone B, polymerizing agents (0.89- to 1.14-fold). Genomic sequencing identified two different heterozygous point mutations in the class I (M40) isotype of beta-tubulin at amino acids 197 (Dbeta197N) and 350 (Kbeta350N) in 2ME2R cells. Tandem mass spectrometry confirmed the presence of both wild-type and the mutant beta-tubulin in 2ME2R cells at the protein level. Consistently, treatment of parental P435 cells with 2-methoxyestradiol resulted in a dose-dependent depolymerization of microtubules, whereas 2ME2R cells remained unaffected. In contrast, paclitaxel affected both cell lines. In the absence of 2-methoxyestradiol, 2ME2R cells were characterized by an elevated level of detyrosination. Upon 2-methoxyestradiol treatment, levels of acetylated and detyrosinated tubulins decreased in P435 cells, while remaining constant in 2ME2R cells. These results, together with our structure-based modeling, show a tight correlation between the antitubulin and antiproliferative effects of 2-methoxyestradiol, consistent with acquired tubulin mutations contributing to 2-methoxyestradiol resistance.

Intratumor cholesteryl ester accumulation is associated with human breast cancer proliferation and aggressive potential: a molecular and clinicopathological study

BackgroundThe metabolic effect of intratumor cholesteryl ester (CE) in breast cancer remains poorly understood. The objective was to analyze the relationship between intratumor CE content and clinicopathological variables in human breast carcinomas.MethodsWe classified 30 breast carcinoma samples into three subgroups: 10 luminal-A tumors (ER+/PR+/Her2-), 10 Her-2 tumors (ER-/PR-/Her2+), and 10 triple negative (TN) tumors (ER-/PR-/Her2-). We analyzed intratumor neutral CE, free cholesterol (FC) and triglyceride (TG) content by thin layer chromatography after lipid extraction. RNA and protein levels of lipid metabolism and invasion mediators were analyzed by real time PCR and Western blot analysis.ResultsGroup-wise comparisons, linear regression and logistic regression models showed a close association between CE-rich tumors and higher histologic grade, Ki-67 and tumor necrosis. CE-rich tumors displayed higher mRNA and protein levels of low-density lipoprotein receptor (LDLR) and scavenger receptor class B member 1 (SCARB1). An increased expression of acetyl-Coenzyme A acetyltransferase 1 (ACAT1) in CE-rich tumors was also reported.ConclusionsIntratumor CE accumulation is intimately linked to proliferation and aggressive potential of breast cancer tumors. Our data support the link between intratumor CE content and poor clinical outcome and open the door to new antitumor interventions.

ASPN and GJB2 Are Implicated in the Mechanisms of Invasion of Ductal Breast Carcinomas.

The mechanism of progression from ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) remains largely unknown. We compared gene expression in tumors with simultaneous DCIS and IDC to decipher how diverse proteins participate in the local invasive process. Twenty frozen tumor specimens with concurrent, but separated, DCIS and IDC were microdissected and evaluated. Total RNA was extracted and microarray analysis was performed using Affymetrix GeneChip® Human Gene 1.0 ST Arrays. Microarray data were validated by quantitative real time reverse transcription-PCR (qRT-PCR) and immunohistochemistry. Controls included seven pure in situ carcinomas, eight fragments from normal breast tissue, and a series of mouse breast carcinomas (MMTV-PyMT). Fifty-six genes were differentially expressed between DCIS and IDC samples. The genes upregulated in IDC samples, and probably associated with invasion, were related to the epithelial-mesenchymal transition (ASPN, THBS2, FN1, SPARC, and COL11A1), cellular adhesion (GJB2), cell motility and progression (PLAUR, PLAU, BGN, ADAMTS16, and ENPP2), extracellular matrix degradation (MMP11, MMP13, and MMP14), and growth/proliferation (ST6GAL2). qRT-PCR confirmed the expression patterns of ASPN, GJB2, ENPP2, ST6GAL2, and TMBS10. Expression of the ASPN and GJB2 gene products was detected by immunohistochemistry in invasive carcinoma foci. The association of GJB2 protein expression with invasion was confirmed by qRT-PCR in mouse tumors (P < 0.05). Conclusions: The upregulation of ASPN and GJB2 may play important roles in local invasion of breast ductal carcinomas.

Genetic up-regulation and overexpression of PLEKHA7 differentiates invasive lobular carcinomas from invasive ductal carcinomas☆

Molecular differentiation between invasive lobular carcinomas (ILCs) and invasive ductal carcinomas (IDCs) of the breast has not been well defined. We investigated gene expression differences between ILCs and IDCs and their correlation with variations in invasiveness and tumor growth. Total RNA was isolated from 30 frozen tumor samples: 10 from ILCs and 20 from IDCs. Gene expression was investigated using the Affymetrix GeneChip Human Gene 1.0 ST Array (Affymetrix, Santa Clara, CA). Data and validation were performed by reverse transcriptase polymerase chain reaction and immunohistochemistry. Gene expression differences between ILCs and IDCs were found in 140 genes. Overall, ILCs showed up-regulation of genes related with cell migration, lipid and fatty acid metabolism, and some transcription factors and showed down-regulation of cell adhesion, actin cytoskeleton, cell proliferation, and energetic metabolism of the tumor cells. Our reverse transcriptase polymerase chain reaction results showed that PLEKHA and TMSB10 expression discriminated ILCs from luminal A IDCs, whereas PLEKHA7, TMSB10, PRDX4, and SERPINB5 discriminated ILCs from luminal B IDCs. At the protein level, Plekha7 was overexpressed in ILCs but not in normal tissue or low-grade IDCs. Moreover, Plekha7 overexpression had an inverse relation with E-cadherin expression. The gene expression profile in ILCs and IDCs differs in several signaling pathways. Our findings suggest that overexpression of PLEKHA7 is common in ILCs and could be a molecular marker to differentiate ILCs from IDCs.

Low-density lipoprotein receptor–related protein 1 is associated with proliferation and invasiveness in Her-2/neu and triple-negative breast carcinomas

Low-density lipoprotein receptor-related protein 1, a member of the low-density lipoprotein cholesterol receptor family, has been implicated in the progression of certain tumors; but it remains unclear whether it plays a role in infiltrating ductal breast carcinomas. We studied a series of 81 ductal breast tumors to determine the correlation of low-density lipoprotein receptor-related protein 1 overexpression with clinicopathologic and immunohistochemical characteristics associated with prognosis. Low-density lipoprotein receptor-related protein 1 overexpression was identified in 14% (11/81) of tumors and was correlated with a high nuclear grade (P = .043), high mitotic index (P = .006), and Ki-67 greater than 20% (P = .047). Furthermore, low-density lipoprotein receptor-related protein 1 expression was associated with aggressive carcinomas (triple-negative tumors [21%, 7/33] and Her-2/neu tumors [17%, 4/24]) but not with hormone-dependent carcinomas (0%, 0/24) (P = .040). There was no correlation between low-density lipoprotein receptor-related protein 1 expression and survival, but a trend was found between low-density lipoprotein receptor-related protein 1 overexpression and tumor recurrence. Low-density lipoprotein receptor-related protein 1 overexpression was related to proliferation and invasiveness in Her-2/neu and triple-negative breast carcinoma. Moreover, patients with low-density lipoprotein receptor-related protein 1-positive tumors had higher cholesterol levels (62.5%, 5/8) than those with low-density lipoprotein receptor-related protein 1-negative tumors (40%, 19/47). Nevertheless, the correlation between low-density lipoprotein receptor-related protein 1 and hypercholesterolemia was not statistically significant; but cholesterol levels were higher in patients with triple-negative breast carcinoma (60%, 15/25) and Her-2/neu carcinomas (40%, 6/15) than in luminal-A carcinomas (20%, 3/15) (P = .046). These findings suggest a relationship between hypercholesterolemia and aggressiveness of ductal breast carcinomas.

Chromosome 17 centromere duplication and responsiveness to anthracycline-based neoadjuvant chemotherapy in breast cancer.

Human epidermal growth factor receptor 2 (HER2) and topoisomerase II alpha (TOP2A) genes have been proposed as predictive biomarkers of sensitivity to anthracycline chemotherapy. Recently, chromosome 17 centromere enumeration probe (CEP17) duplication has also been associated with increased responsiveness to anthracyclines. However, reports are conflicting and none of these tumor markers can yet be considered a clinically reliable predictor of response to anthracyclines. We studied the association of TOP2A gene alterations, HER2 gene amplification, and CEP17 duplication with response to anthracycline-based neoadjuvant chemotherapy in 140 patients with operable or locally advanced breast cancer. HER2 was tested by fluorescence in situ hybridization and TOP2A and CEP17 by chromogenic in situ hybridization. Thirteen patients (9.3%) achieved pathologic complete response (pCR). HER2 amplification was present in 24 (17.5%) of the tumors. TOP2A amplification occurred in seven tumors (5.1%). CEP17 duplication was detected in 13 patients (9.5%). CEP17 duplication correlated with a higher rate of pCR [odds ratio (OR) 6.55, 95% confidence interval (95% CI) 1.25-34.29, P = .026], and analysis of TOP2A amplification showed a trend bordering on statistical significance (OR 6.97, 95% CI 0.96-50.12, P = .054). TOP2A amplification and CEP17 duplication combined were strongly associated with pCR (OR 6.71, 95% CI 1.66-27.01, P = .007). HER2 amplification did not correlate with pCR. Our results suggest that CEP17 duplication predicts pCR to primary anthracycline-based chemotherapy. CEP17 duplication, TOP2A amplifications, and HER2 amplifications were not associated with prognosis.