Joan Climent

FBXW7 Targets mTOR for Degradation and Cooperates with PTEN in Tumor Suppression

The enzyme mTOR (mammalian target of rapamycin) is a major target for therapeutic intervention to treat many human diseases, including cancer, but very little is known about the processes that control levels of mTOR protein. Here, we show that mTOR is targeted for ubiquitination and consequent degradation by binding to the tumor suppressor protein FBXW7. Human breast cancer cell lines and primary tumors showed a reciprocal relation between loss of FBXW7 and deletion or mutation of PTEN (phosphatase and tensin homolog), which also activates mTOR. Tumor cell lines harboring deletions or mutations in FBXW7 are particularly sensitive to rapamycin treatment, which suggests that loss of FBXW7 may be a biomarker for human cancers susceptible to treatment with inhibitors of the mTOR pathway.

No paradox, no progress: inverse cancer comorbidity in people with other complex diseases

In the past 5 years, several leading groups have attempted to explain why individuals with Downs syndrome have a reduced risk of many solid tumours and an increased risk of leukaemia and testicular cancer. Niels Bohr, the Danish physicist, noted that a paradox could initiate progress. We think that the paradox of a medical disorder protecting against cancer could be formalised in a new model of inverse cancer morbidity in people with other serious diseases. In this Personal View, we review evidence from epidemiological and clinical studies that supports a consistently lower than expected occurrence of cancer in patients with Downs syndrome, Parkinsons disease, schizophrenia, diabetes, Alzheimers disease, multiple sclerosis, and anorexia nervosa. Intriguingly, most comorbidities are neuropsychiatric or CNS disorders. We provide a brief overview of evidence indicating genetic and molecular connections between cancer and these complex diseases. Inverse comorbidity could be a valuable model to investigate common or related pathways or processes and test new therapies, but, most importantly, to understand why certain people are protected from the malignancy.

Co-amplified genes at 8p12 and 11q13 in breast tumors cooperate with two major pathways in oncogenesis

Co-amplification at chromosomes 8p11–8p12 and 11q12–11q14 occurs often in breast tumors, suggesting possible cooperation between genes in these regions in oncogenesis. We used high-resolution array comparative genomic hybridization (array CGH) to map the minimal amplified regions. The 8p and 11q amplicons are complex and consist of at least four amplicon cores at each site. Candidate oncogenes mapping to these regions were identified by combining copy number and RNA and protein expression analyses. These studies also suggested that CCND1 at 11q13 induced expression of ZNF703 mapping at 8p12, which was subsequently shown to be mediated by the Rb/E2F pathway. Nine candidate oncogenes from 8p12 and four from 11q13 were further evaluated for oncogenic function. None of the genes individually promoted colony formation in soft agar or collaborated with each other functionally. On the other hand, FGFR1 and DDHD2 at 8p12 cooperated functionally with MYC, whereas CCND1 and ZNF703 cooperated with a dominant negative form of TP53. These observations highlight the complexity and functional consequences of the genomic rearrangements that occur in these breast cancer amplicons, including transcriptional cross-talk between genes in the 8p and 11q amplicons, as well as their cooperation with major pathways of tumorigenesis.

Inverse and direct cancer comorbidity in people with central nervous system disorders: a meta-analysis of cancer incidence in 577,013 participants of 50 observational studies

Background: There is a lack of scientific consensus about cancer comorbidity in people with central nervous system (CNS) disorders. This study assesses the co-occurrence of cancers in patients with CNS disorders, including Alzheimers disease (AD), amyotrophic lateral sclerosis (ALS), autism spectrum disorders, Downs syndrome (DS), Huntingtons disease (HD), multiple sclerosis (MS), Parkinsons disease (PD) and schizophrenia (SCZ). Method: Comprehensive search in PubMed/MEDLINE, Scopus and ISI Web of Knowledge of the literature published before March 2013. We identified 51 relevant articles from 2,229 discrete references, 50 of which contained data suitable for quantitative synthesis (577,013 participants). Pooled effect sizes (ES) were calculated using multiple random-effects meta-analyses. Sources of heterogeneity and uncertainty were explored by means of subgroup and sensitivity analyses, respectively. Results: The presence of CNS disorders was associated with a reduced co-occurrence of cancer (ES = 0.92; 95% confidence interval, CI: 0.87-0.98; I2 = 94.5%). A consistently lower overall co-occurrence of cancer was detected in patients with neurodegenerative disorders (ES = 0.80; 95% CI: 0.75- 0.86; I2 = 82.8%), and in those with AD (ES = 0.32; 95% CI: 0.22-0.46; I2 = 0.0%), PD (ES = 0.83; 95% CI: 0.76-0.91; I2 = 80.0%), MS (ES = 0.91; 95% CI: 0.87-0.95; I2 = 30.3%) and HD (ES = 0.53; 95% CI: 0.42-0.67; I2 = 56.4%). Patients with DS had a higher overall co-occurrence of cancer (ES = 1.46; 95% CI: 1.08-1.96; I2 = 87.9%). No association was observed between cancer and ALS (ES = 0.97; 95% CI: 0.76-1.25; I2 = 0.0%) or SCZ (ES = 0.98; 95% CI: 0.90-1.07; I2 = 96.3%). Patients with PD, MS and SCZ showed (a) higher co-occurrence of some specific cancers (e.g. PD with melanoma, MS with brain cancers and SCZ with breast cancer), and (b) lower co-occurrence of other specific cancers (e.g. lung, prostate and colorectal cancers in PD; lung and prostate cancers in MS; and melanoma and prostate cancer in SCZ). Conclusion: Increased and decreased co-occurrence of cancer in patients with CNS disorders represents an opportunity to discover biological and non-biological connections between these complex disorders.

Deletion of Chromosome 11q Predicts Response to Anthracycline-Based Chemotherapy in Early Breast Cancer

Despite the recent consensus on the eligibility of adjuvant systemic therapy in patients with lymph node-negative breast cancer (NNBC) based on clinicopathologic criteria, specific biological markers are needed to predict sensitivity to the different available therapeutic options. We examined the feasibility of developing a genomic predictor of chemotherapy response and recurrence risk in 185 patients with NNBC using assembled arrays containing 2,460 bacterial artificial chromosome clones for scanning the genome for DNA copy number changes. After surgery, 90 patients received anthracycline-based chemotherapy, whereas 95 did not. Tamoxifen was administered to patients with hormone receptor-positive tumors. The association of genomic and clinicopathologic data and outcome was computed using Cox proportional hazard models and multiple testing adjustment procedures. Analysis of NNBC genomes revealed a common genomic signature. Specific DNA copy number aberrations were associated with hormonal receptor status, but not with other clinicopathologic variables. In patients treated with chemotherapy, none of the genomic changes were significantly correlated with recurrence. In patients not receiving chemotherapy, deletion of eight bacterial artificial chromosome clones clustered to chromosome 11q was independently associated with relapse (disease-free survival at 10 years+/-SE, 40%+/-14% versus 86%+/-6%; P<0.0001). The 54 patients with deletion of 11q (29%) did not present more aggressive clinicopathologic features than those without 11q loss. The adverse influence of 11q deletion on clinical outcome was confirmed in an independent validation series of 88 patients with NNBC. Our data suggests that patients with NNBC with the 11q deletion might benefit from anthracycline-based chemotherapy despite other clinical, pathologic, or genetic features. However, these initial findings should be evaluated in randomized clinical trials.

Deletion of the PER3 Gene on Chromosome 1p36 in Recurrent ER-Positive Breast Cancer

PURPOSE To investigate the role of the PER3 circadian rhythm gene, located within the commonly deleted region of chromosome 1p36, in human breast cancer development. PATIENTS AND METHODS The frequency of genetic alterations at 1p36 and PER3 gene copy number status were analyzed in 180 lymph node-negative breast cancers from patients who had received treatment with chemotherapy and/or tamoxifen. The expression levels of PER3 were also analyzed using published microarray profiles from > 400 breast cancer samples. Finally, the effect of loss of Per3 on tumor susceptibility was tested using two mouse models of breast cancer. RESULTS Deletion of PER3 is directly related to tumor recurrence in patients with estrogen receptor (ER) - positive breast cancers treated with tamoxifen. Low expression of PER3 mRNA is associated with poor prognosis, particularly in a subset of tumors that are ER positive, and either luminal A or ERBB2-positive tumors. Mice deficient in Per3 showed increased susceptibility to breast cancer induced by carcinogen treatment or by overexpression of Erbb2. CONCLUSION Disruption of PER3 function may serve as an indicator of probability of tumor recurrence in patients with ER-positive tumors. Further investigations of this pathway may reveal links between deregulation of sleep homeostasis and breast tumorigenesis.

Hipk2 cooperates with p53 to suppress γ-ray radiation-induced mouse thymic lymphoma.

A genome-wide screen for genetic alterations in radiation-induced thymic lymphomas generated from p53+/− and p53−/− mice showed frequent loss of heterozygosity (LOH) on chromosome 6. Fine mapping of these LOH regions revealed three non-overlapping regions, one of which was refined to a 0.2 Mb interval that contained only the gene encoding homeobox-interacting protein kinase 2 (Hipk2). More than 30% of radiation-induced tumors from both p53+/− and p53−/− mice showed heterozygous loss of one Hipk2 allele. Mice carrying a single inactive allele of Hipk2 in the germline were susceptible to induction of tumors by γ-radiation, but most tumors retained and expressed the wild-type allele, suggesting that Hipk2 is a haploinsufficient tumor suppressor gene for mouse lymphoma development. Heterozygous loss of both Hipk2 and p53 confers strong sensitization to radiation-induced lymphoma. We conclude that Hipk2 is a haploinsufficient lymphoma suppressor gene.

Selective concomitant inhibition of mTORC1 and mTORC2 activity in estrogen receptor negative breast cancer cells by BN107 and oleanolic acid.

Hormonal, targeted and chemotherapeutic strategies largely depend on the expression of their cognate receptors and are often accompanied by intolerable toxicities. Effective and less toxic therapies for estrogen receptor negative (ER−) breast cancers are urgently needed. Here, we present the potential molecular mechanisms mediating the selective pro‐apoptotic effect induced by BN107 and its principle terpene, oleanolic acid (OA), on ER− breast cancer cells. A panel of breast cancer cell lines was examined and the most significant cytotoxic effect was observed in ER− breast lines. Apoptosis was the major cellular pathway mediating the cytotoxicity of BN107. We demonstrated that sensitivity to BN107 was correlated to the status of ERα. Specifically, the presence of functional ERα protected cells from BN107‐induced apoptosis and absence of ERα increased the sensitivity. BN107, an extract rich in OA derivatives, caused rapid alterations in cholesterol homeostasis, presumably by depleting cholesterol in lipid rafts (LRs), which subsequently interfered with signaling mediated by LRs. We showed that BN107 or OA treatment in ER− breast cancer cells resulted in rapid and specific inhibition of LR‐mediated survival signaling, namely mTORC1 and mTORC2 activities, by decreasing the levels of the mTOR/FRAP1, RAPTOR and RICTOR. Cotreatment with cholesterol abolished the proapoptotic effect and restored the disrupted mTOR activities. This is the first report demonstrating possible concomitant inhibition of both mTORC1 and mTORC2 activities by modulating the levels of protein constituents present in these signaling complexes, and thus provides a basis for future development of OA‐based mTOR inhibitors.

MicroRNA profile in very young women with breast cancer

BackgroundBreast cancer is rarely diagnosed in very young women (35years old or younger), and it often presents with distinct clinical-pathological features related to a more aggressive phenotype and worse prognosis when diagnosed at this early age. A pending question is whether breast cancer in very young women arises from the deregulation of different underlying mechanisms, something that will make this disease an entity differentiated from breast cancer diagnosed in older patients.MethodsWe performed a comprehensive study of miRNA expression using miRNA Affymetrix2.0 array on paraffin-embedded tumour tissue of 42 breast cancer patients 35 years old or younger, 17 patients between 45 and 65 years old and 29 older than 65 years. Data were statistically analyzed by t-test and a hierarchical clustering via average linkage method was conducted. Results were validated by qRT-PCR. Putative targeted pathways were obtained using DIANA miRPath online software.ResultsThe results show a differential and unique miRNA expression profile of 121 miRNAs (p-value <0.05), 96 of those with a FDR-value <0.05. Hierarchical clustering grouped the samples according to their age, but not by subtype nor by tumour characteristics. We were able to validate by qRT-PCR differences in the expression of 6 miRNAs: miR-1228*, miR-3196, miR-1275, miR-92b, miR-139 and miR-1207. Moreover, all of the miRNAs maintained the expression trend. The validated miRNAs pointed out pathways related to cell motility, invasion and proliferation.ConclusionsThe study suggests that breast cancer in very young women appears as a distinct molecular signature. To our knowledge, this is the first time that a validated microRNA profile, distinctive to breast cancer in very young women, has been presented. The miRNA signature may be relevant to open an important field of research in order to elucidate the underlying mechanism in this particular disease, which in a more clinical setting, could potentially help to identify therapeutic targets in this particular set of patients.

MicroRNA Profile in Response to Doxorubicin Treatment in Breast Cancer

Chemotherapy treatment is the standard in triple negative breast cancers, a cancer subgroup which lacks a specific target. The mechanisms leading to the response, as well as any markers that allow the differentiation between responder and non‐responder groups prior to treatment are unknown. In parallel, miRNAs can act as oncogenes or tumor suppressors and there is evidence of their involvement in promoting resistance to anticancer drugs. Therefore we hypothesized that changes in miRNA expression after doxorubicin treatment may also be relevant in treatment response. Objective: To study miRNAs that are differentially expressed in response to doxorubicin treatment. Methods: One luminal‐A and two triple negative, breast cancer cell lines were exposed to doxorubicin. Microarray analysis was performed to identify the common and differentially modified miRNAs. Genes and pathways that are theoretically regulated by these miRNAs were analyzed. Results: Thirteen miRNAs common to all three lines were modified, in addition to 25 that were specific to triple negative cell lines, and 69 that changed only in the luminal‐A cell line. This altered expression pattern seemed to be more strongly related to the breast cancer subgroup than to the treatment. The analysis of target genes revealed that cancer related pathways were the most affected by these miRNAs, moreover many of them had been previously related to chemotherapy resistance; thus suggesting follow‐up studies. Additionally, through functional assays, we showed that miR‐548c‐3p is implicated in doxorubicin‐treated MCF‐7 cell viability, suggesting a role for this miRNA in resistance. J. Cell. Biochem. 116: 2061–2073, 2015.