Functional pathway characterized by gene expression analysis of supraclavicular lymph node metastasis-positive breast cancer

Synthetic Lethality between Cohesin and WNT Signaling Pathways in Diverse Cancer Contexts

Cohesin is a highly conserved ring-shaped complex involved in topologically embracing chromatids, gene expression regulation, genome compartmentalization, and genome stability maintenance. Genomic analyses have detected mutations in the cohesin complex in a wide array of human tumors. These findings have led to increased interest in cohesin as a potential target in cancer therapy. Synthetic lethality has been suggested as an approach to exploit genetic differences in cancer cells to influence their selective killing. In this study, we show that mutations in ESCO1, NIPBL, PDS5B, RAD21, SMC1A, SMC3, STAG2, and WAPL genes are synthetically lethal with stimulation of WNT signaling obtained following LY2090314 treatment, a GSK3 inhibitor, in several cancer cell lines. Moreover, treatment led to the stabilization of β-catenin and affected the expression of c-MYC, probably due to the occupancy decrease in cohesin at the c-MYC promoter. Finally, LY2090314 caused gene expression dysregulation mainly involving pathways related to transcription regulation, cell proliferation, and chromatin remodeling. For the first time, our work provides the underlying molecular basis for synthetic lethality due to cohesin mutations and suggests that targeting the WNT may be a promising therapeutic approach for tumors carrying mutated cohesin.

The synergism of SMC1A cohesin gene silencing and bevacizumab against colorectal cancer

BACKGROUND

SMC1A is a subunit of the cohesin complex that participates in many DNA- and chromosome-related biological processes. Previous studies have established that SMC1A is involved in cancer development and in particular, is overexpressed in chromosomally unstable human colorectal cancer (CRC). This study aimed to investigate whether SMC1A could serve as a therapeutic target for CRC.

METHODS

At first, we studied the effects of either SMC1A overexpression or knockdown in vitro. Next, the outcome of SMC1A knocking down (alone or in combination with bevacizumab, a monoclonal antibody against vascular endothelial growth factor) was analyzed in vivo.

RESULTS

We found that SMC1A knockdown affects cell proliferation and reduces the ability to grow in anchorage-independent manner. Next, we demonstrated that the silencing of SMC1A and the combo treatment were effective in increasing overall survival in a xenograft mouse model. Functional analyses indicated that both treatments lead to atypical mitotic figures and gene expression dysregulation. Differentially expressed genes were implicated in several pathways including gene transcription regulation, cellular proliferation, and other transformation-associated processes.

CONCLUSIONS

These results indicate that SMC1A silencing, in combination with bevacizumab, can represent a promising therapeutic strategy for human CRC.

Prediction for Distant Metastasis of Breast Cancer Using Dynamic Contrast-Enhanced Magnetic Resonance Imaging Images under Deep Learning

This research aimed to explore the effect of using magnetic resonance imaging (MRI) radiomic features to establish a model for predicting distant metastasis under dynamic contrast-enhanced MRI imaging with deep learning algorithms. The deep learning algorithm was used to segment the images. A total of 96 cases with 100 lesions were included in the metastatic group, including 2 cases of bifocal breast cancer and 2 cases of multifocal breast cancer. There were 192 cases in the nonmetastatic group, with 197 lesions, including 5 cases of multifocal breast cancer. After dynamic contrast-enhancement, the morphological features and grayscale statistical features were extracted from the lesions to establish a prediction model through sum-sum check and feature dimension reduction. The accuracy, sensitivity, specificity, and area under receiver operator characteristic curve (AUC) of prediction models based only on imaging features were compared with those created by combining radiomic features with clinical and pathological features. The created predictive model based on radiomic features for distant metastases in breast cancer showed a sensitivity of 66.7%, a specificity of 84.2%, an accuracy of 78.3%, and an AUC of 0.744. The sensitivity of the prediction model for distant metastasis of breast cancer was 67.7%, the specificity was 86.8%, the accuracy was 80.5%, and the AUC was 0.763. Bone, lung, and liver were the most common distant metastatic sites of breast cancer. Under the dynamic contrast-enhanced MRI of deep learning, the prediction model combining radiomic features with clinical and pathological features showed better predictive performance.

Tau and stathmin proteins in breast cancer: A potential therapeutic target

Breast cancer is the most common malignant neoplasm among women, responsible for 30% of all malignant tumours, and the second most significant reason of cancer fatality in women. Treatment failure and tumour recurrence are common outcomes of chemotherapy when patients develop multidrug resistance (MDR). New therapeutic methods like molecularly targeted therapeutic interventions need a thorough understanding of malignant tumour's molecular processes. Numerous studies published in the last few years indicate that stathmin and tubulin-associated units (tau) are upregulated in a range of human malignant tumours, suggesting that they may enhance the incidence and progression of malignancies. By promoting cancer cell reproduction, infiltration and generating drug resistance, these proteins aid in the disease's development. Existing information on the expression of tau protein and stathmin in breast cancer, as well as their involvement in treatment methods, is summarized in this literature review.

The multifaceted roles of cohesin in cancer

The cohesin complex controls faithful chromosome segregation by pairing sister chromatids after DNA replication until mitosis. In addition, it is crucial for hierarchal three-dimensional organization of the genome, transcription regulation and maintaining DNA integrity. The core complex subunits SMC1A, SMC3, STAG1/2, and RAD21 as well as its modulators, have been found to be recurrently mutated in human cancers. The mechanisms by which cohesin mutations trigger cancer development and disease progression are still poorly understood. Since cohesin is involved in a range of chromosome-related processes, the outcome of cohesin mutations in cancer is complex. Herein, we discuss recent discoveries regarding cohesin that provide new insight into its role in tumorigenesis.

Identification and Roles of miR-29b-1-3p and miR29a-3p-Regulated and Non-Regulated lncRNAs in Endocrine-Sensitive and Resistant Breast Cancer Cells

Despite improvements in the treatment of endocrine-resistant metastatic disease using combination therapies in patients with estrogen receptor α (ERα) primary tumors, the mechanisms underlying endocrine resistance remain to be elucidated. Non-coding RNAs (ncRNAs), including microRNAs (miRNA) and long non-coding RNAs (lncRNA), are targets and regulators of cell signaling pathways and their exosomal transport may contribute to metastasis. Previous studies have shown that a low expression of miR-29a-3p and miR-29b-3p is associated with lower overall breast cancer survival before 150 mos. Transient, modest overexpression of miR-29b1-3p or miR-29a-3p inhibited MCF-7 tamoxifen-sensitive and LCC9 tamoxifen-resistant cell proliferation. Here, we identify miR-29b-1/a-regulated and non-regulated differentially expressed lncRNAs in MCF-7 and LCC9 cells using next-generation RNA seq. More lncRNAs were miR-29b-1/a-regulated in LCC9 cells than in MCF-7 cells, including DANCR, GAS5, DSCAM-AS1, SNHG5, and CRND. We examined the roles of miR-29-regulated and differentially expressed lncRNAs in endocrine-resistant breast cancer, including putative and proven targets and expression patterns in survival analysis using the KM Plotter and TCGA databases. This study provides new insights into lncRNAs in endocrine-resistant breast cancer.

Mutant p53 stimulates cell invasion through an interaction with Rad21 in human ovarian cancer cells

Missense mutations of TP53 are extremely common, and mutant p53 accumulation and gain-of-function play crucial roles in human ovarian cancer. Here, we investigated the role of mutant p53 in cell migration and invasion as well as its underlying molecular mechanisms in human ovarian cancer cells. Overexpression of mutant p53 significantly increased migration and invasion in p53-null SKOV3 cells. In contrast, knockdown of mutant p53 significantly compromised mutant p53-induced cell migration and invasion. Microarray analysis revealed that several migration/invasion-related genes, including S1PR1 (Sphingosine-1-phosphate receptor 1) and THBS1 (Thrombospodin 1), were significantly upregulated in SKOV3 cells that overexpressed mutant p53-R248 (SKOV3^R248). We found that Rad21 is involved in the transcriptional regulation of the migration/invasion-related genes induced by mutant p53-R248. Knockdown of Rad21 significantly attenuated the mutant p53-R248-induced invasion and the expressions of S1PR1 and THBS1. Moreover, co-immunoprecipitation and chromatin immunoprecipitation assays revealed that mutant p53 interacts with Rad21 and binds to the Rad21-binding elements in the S1PR1 and THBS1 genes. Finally, downregulation of S1PR1 significantly attenuated the invasion driven by mutant p53-R248. These novel findings reveal that mutant p53-R248 maintains gain-of-function activity to stimulate cell invasion and induces the related gene expressions through an interaction with Rad21 in human ovarian cancer cells.

Targeted proteomics driven verification of biomarker candidates associated with breast cancer aggressiveness

Breast cancer is the most common and molecularly relatively well characterized malignant disease in women, however, its progression to metastatic cancer remains lethal for 78% of patients 5years after diagnosis. Novel markers could identify the high risk patients and their verification using quantitative methods is essential to overcome genetic, inter-tumor and intra-tumor variability and translate novel findings into cancer diagnosis and treatment. We recently identified 13 proteins associated with estrogen receptor, tumor grade and lymph node status, the key factors of breast cancer aggressiveness, using untargeted proteomics. Here we verified these findings in the same set of 96 tumors using targeted proteomics based on selected reaction monitoring with mTRAQ labeling (mTRAQ-SRM), transcriptomics and immunohistochemistry and validated in 5 independent sets of 715 patients using transcriptomics. We confirmed: (i) positive association of anterior gradient protein 2 homolog (AGR2) and periostin (POSTN) and negative association of annexin A1 (ANXA1) with estrogen receptor status; (ii) positive association of stathmin (STMN1), cofilin-1 (COF1), plasminogen activator inhibitor 1 RNA-binding protein (PAIRBP1) and negative associations of thrombospondin-2 (TSP2) and POSTN levels with tumor grade; and (iii) positive association of POSTN, alpha-actinin-4 (ACTN4) and STMN1 with lymph node status. This study highlights a panel of gene products that can contribute to breast cancer aggressiveness and metastasis, the understanding of which is important for development of more precise breast cancer treatment.

Systemic identification of estrogen-regulated genes in breast cancer cells through cap analysis of gene expression mapping

To explore the estrogen-regulated genes genome-widely in breast cancer, cap analysis of gene expression (CAGE) sequencing was performed in MCF-7 cells under estrogen treatment. Estrogen-regulated expressional changes were found in 1537 CAGE tag clusters (TCs) (⩾1.5 or ⩽0.66-folds). Among them, 15 TCs were situated in the vicinity of (⩽10 kb) reported estrogen receptor-binding sites. Knockdown experiments of the 15 TC-associated genes demonstrated that the genes such as RAMP3, ISOC1 and GPRC5C potentially regulate the growth or migration of MCF-7 cells. These results suggest that CAGE sequencing will reveal novel estrogen target genes in breast cancer.

Significant overexpression of DVL1 in Taiwanese colorectal cancer patients with liver metastasis

Undetected micrometastasis plays a key role in the metastasis of cancer in colorectal cancer (CRC) patients. The aim of this study is to identify a biomarker of CRC patients with liver metastasis through the detection of circulating tumor cells (CTCs). Microarray and bioinformatics analysis of 10 CRC cancer tissue specimens compared with normal adjacent tissues revealed that 31 genes were up-regulated (gene expression ratio of cancer tissue to paired normal tissue > 2) in the cancer patients. We used a weighted enzymatic chip array (WEnCA) including 31 prognosis-related genes to investigate CTCs in 214 postoperative stage I-III CRC patients and to analyze the correlation between gene expression and clinico-pathological parameters. We employed the immunohistochemistry (IHC) method with polyclonal mouse antibody against DVL1 to detect DVL1 expression in 60 CRC patients. CRC liver metastasis occurred in 19.16% (41/214) of the patients. Using univariate analysis and multivariate proportional hazards regression analysis, we found that DVL1 mRNA overexpression had a significant, independent predictive value for liver metastasis in CRC patients (OR: 5.764; 95% CI: 2.588-12.837; p < 0.0001 on univariate analysis; OR: 3.768; 95% CI: 1.469-9.665; p = 0.006 on multivariate analysis). IHC staining of the immunoreactivity of DVL1 showed that DVL1 was localized in the cytoplasm of CRC cells. High expression of DVL1 was observed in 55% (33/60) of CRC tumor specimens and was associated significantly with tumor depth, perineural invasion and liver metastasis status (all p < 0.05). Our experimental results demonstrated that DVL1 is significantly overexpressed in CRC patients with liver metastasis, leading us to conclude that DVL1 could be a potential prognostic and predictive marker for CRC patients.

Cell cycle inhibition therapy that targets stathmin in in vitro and in vivo models of breast cancer

Stathmin is the founding member of a family of microtubule-destabilizing proteins that have a critical role in the regulation of mitosis. Stathmin is expressed at high levels in breast cancer and its overexpression is linked to disease progression. Although there is a large body of evidence to support a role for stathmin in breast cancer progression, the validity of stathmin as a viable therapeutic target for breast cancer has not been investigated. Here, we used a bicistronic adenoviral vector that co-expresses green fluorescent protein and a ribozyme that targets stathmin messenger RNA in preclinical breast cancer models with different estrogen receptor (ER) status. We examined the effects of anti-stathmin ribozyme on the malignant phenotype of breast cancer cells in vitro and in xenograft models in vivo both as a single agent and in combination with chemotherapeutic agents. Adenovirus-mediated gene transfer of anti-stathmin ribozyme resulted in a dose-dependent inhibition of proliferation and clonogenicity associated with a G2/M arrest and increase in apoptosis in both ER-positive and ER-negative breast cancer cell lines. This inhibition was markedly enhanced when stathmin-inhibited breast cancer cells were exposed to low concentrations of taxol, which resulted in virtually complete loss of the malignant phenotype. Interestingly, breast cancer xenografts treated with low doses of anti-stathmin therapy and taxol showed regression in a majority of tumors, while some tumors stopped growing completely. In contrast, combination of anti-stathmin ribozyme and adriamycin resulted in only a modest inhibition of growth in vitro and in breast cancer xenografts in vivo. Although inhibition of tumor growth was observed in both the combination treatment groups compared with groups treated with single agent alone, combination of anti-stathmin therapy and taxol had a more profound inhibition of tumorigenicity, as both agents target the microtubule pathway. Clinically, these findings are highly relevant because taxol is one of the most active chemotherapeutic agents in breast cancer. These studies provide the proof-of-principle that stathmin provides an attractive molecular target, which could serve as a primary focus of novel approaches to breast cancer.

Genotyping of stathmin and its association with clinical factors and survival in patients with ovarian cancer

Stathmin is closely correlated with the progression and prognosis of a number of types of human cancer. The present study analyzed the associations between genetic variations in the stathmin gene and clinical outcomes of ovarian cancer. A total of 178 patients with epithelial ovarian cancer were treated with cytoreductive surgery followed by platinum-based chemotherapy. DNA was extracted from fresh tumor samples obtained during surgery. A total of 32 DNA samples were selected randomly for resequencing of the stathmin gene. Tag single nucleotide polymorphisms (SNPs) were identified based on the haplotype model as analyzed by PolyPhred software. Direct sequencing was employed in the genotyping of stathmin in 178 cases. A total of 10 nucleotide variations in stathmin were identified, of which 3 high-frequency variations were known SNPs from databases and 7 were new variations with low frequencies. The tag SNPs rs159531 and rs11376635 were selected from the linkage disequilibrium block of the gene to genotype stathmin in 178 cases. The distribution of the rs159531 genotype in ovarian cancer was 52.8% C/C, 35.4% C/T and 11.2% T/T. The distribution of the rs11376635 genotype in ovarian cancer was 32.0% G/G, 48.3% G/-, 18.5% -/-. The main haplotypes calculated by phase2.0 software were 55.6% CG, 27.8% T-, 15.4% C- and 1.2% TG. However, no associations between the stathmin genotype or haplotype and the outcomes in patients with ovarian cancer were observed. The stathmin genotype and haplotype were not associated with the phenotype of patients with ovarian cancer.

SMC1A knockdown induces growth suppression of human lung adenocarcinoma cells through G1/S cell cycle phase arrest and apoptosis pathways in vitro

SMC1A (structural maintenance of chromosomes 1A), which encodes a structural subunit of the cohesin protein complex, is necessary for the process of sister chromatid cohesion during the cell cycle. Mutation and deregulation of SMC1A are highly relevant to diverse human diseases, including Cornelia de Lange syndrome and malignant carcinomas. In order to further investigate the role of SMC1A in the oncogenesis of lung cancer, SMC1A-specific short hairpin RNA (shRNA)-expressing lentivirus (Lv-shSMC1A) was constructed and used to infect A549 and H1299 cells. SMC1A mRNA and protein expression levels were downregulated in A549 and H1299 cells as demonstrated by real-time PCR and western blot assays. We found that SMC1A inhibition resulted in significantly impaired proliferation and colony formation as well as reduced invasiveness of tumor cells. Notably, Lv-shSMC1A-infected cancer cells exhibited a greater proportion of cells in the G0/G1 phase, but a lower proportion of S phase cells, compared to the parent or Lv-shCon infected cancer cells. Moreover, a greater proportion of sub-G1 apoptotic cells was observed in Lv-shSMC1A-infected cells. These results suggest that SMC1A is a novel proliferation regulator that promotes the growth of lung cancer cells, and that down-regulation of SMC1A expression induces growth suppression of A549 and H1299 cells via G1/S cell cycle phase arrest and apoptosis pathways. Therefore, SMC1A may serve as a new molecular target for lung cancer therapy.

MiR-101 is involved in human breast carcinogenesis by targeting Stathmin1

Background

MicroRNA-101 (miR-101) expression is negatively associated with tumor growth and blood vessel formation in several solid epithelial cancers. However, the role of miR-101 in human breast cancer remains elusive.

Results

MiR-101 was significantly decreased in different subtypes of human breast cancer tissues compared with that in adjacent normal breast tissues (P<0.01). Up-regulation of miR-101 inhibited cell proliferation, migration and invasion, and promoted cell apoptosis in ER alpha-positive and ER alpha-negative breast cancer cells and normal breast cells. Down-regulation of miR-101 displayed opposite effects on cell growth and metastasis. Further investigation revealed a significant inverse correlation between the expression of miR-101 and Stathmin1 (Stmn1), and miR-101 could bind to the 3′-untranslated region (UTR) of Stmn1 to inhibit Stmn1 translation. The inhibition of cell growth and metastasis induced by up-regulation of miR-101 was partially restored by overexpresson of Stmn1. Knockdown of Stmn1 attenuates the down-regulation of miR-101-mediated enhancement of cell growth and metastasis. More importantly, in vivo analysis found that Stmn1 mRNA and protein level in different subtypes of human breast cancer tissues, contrary to the down-regulation of miR-101, were significantly elevated.

Conclusions

This study demonstrates that down-regulation of miR-101 in different subtypes of human breast cancer tissues is linked to the increase of cellular proliferation and invasiveness via targeting Stmn1, which highlights novel regulatory mechanism in breast cancer and may provide valuable clues for the future clinical diagnosis of breast cancer.

Enhanced RAD21 cohesin expression confers poor prognosis in BRCA2 and BRCAX, but not BRCA1 familial breast cancers

INTRODUCTION

The RAD21 gene encodes a key component of the cohesin complex, which is essential for chromosome segregation, and together with BRCA1 and BRCA2, for high-fidelity DNA repair by homologous recombination. Although its expression correlates with early relapse and treatment resistance in sporadic breast cancers, it is unclear whether familial breast cancers behave in a similar manner.

METHODS

We performed an immunohistochemical analysis of RAD21 expression in a cohort of 94 familial breast cancers (28 BRCA1, 27 BRCA2, and 39 BRCAX) and correlated these data with genotype and clinicopathologic parameters, including survival. In these cancers, we also correlated RAD21 expression with genomic expression profiling and gene copy-number changes and miRNAs predicted to target RAD21.

RESULTS

No significant differences in nuclear RAD21 expression were observed between BRCA1 (12 (43%) of 28), BRCA2 (12 (44%) of 27), and BRCAX cancers (12 (33%) of 39 (p = 0.598). No correlation was found between RAD21 expression and grade, size, or lymph node, ER, or HER2 status (all P > 0.05). As for sporadic breast cancers, RAD21 expression correlated with shorter survival in grade 3 (P = 0.009) and but not in grade 1 (P = 0.065) or 2 cancers (P = 0.090). Expression of RAD21 correlated with poorer survival in patients treated with chemotherapy (P = 0.036) but not with hormonal therapy (P = 0.881). RAD21 expression correlated with shorter survival in BRCA2 (P = 0.006) and BRCAX (P = 0.008), but not BRCA1 cancers (P = 0.713). Changes in RAD21 mRNA were reflected by genomic changes in DNA copy number (P < 0.001) and by RAD21 protein expression, as assessed with immunohistochemistry (P = 0.047). High RAD21 expression was associated with genomic instability, as assessed by the total number of base pairs affected by genomic change (P = 0.048). Of 15 miRNAs predicted to target RAD21, mir-299-5p inversely correlated with RAD21 expression (P = 0.002).

CONCLUSIONS

Potential use of RAD21 as a predictive and prognostic marker in familial breast cancers is hence feasible and may therefore take into account the patient's BRCA1/2 mutation status.

Gene regulation by cohesin in cancer: is the ring an unexpected party to proliferation?

Cohesin is a multisubunit protein complex that plays an integral role in sister chromatid cohesion, DNA repair, and meiosis. Of significance, both over- and underexpression of cohesin are associated with cancer. It is generally believed that cohesin dysregulation contributes to cancer by leading to aneuploidy or chromosome instability. For cancers with loss of cohesin function, this idea seems plausible. However, overexpression of cohesin in cancer appears to be more significant for prognosis than its loss. Increased levels of cohesin subunits correlate with poor prognosis and resistance to drug, hormone, and radiation therapies. However, if there is sufficient cohesin for sister chromatid cohesion, overexpression of cohesin subunits should not obligatorily lead to aneuploidy. This raises the possibility that excess cohesin promotes cancer by alternative mechanisms. Over the last decade, it has emerged that cohesin regulates gene transcription. Recent studies have shown that gene regulation by cohesin contributes to stem cell pluripotency and cell differentiation. Of importance, cohesin positively regulates the transcription of genes known to be dysregulated in cancer, such as Runx1, Runx3, and Myc. Furthermore, cohesin binds with estrogen receptor α throughout the genome in breast cancer cells, suggesting that it may be involved in the transcription of estrogen-responsive genes. Here, we will review evidence supporting the idea that the gene regulation function of cohesin represents a previously unrecognized mechanism for the development of cancer.

The dark side of cohesin: the carcinogenic point of view

Genome instability is a hallmark of cancer cells and how it arises is still not completely understood. Correct chromosome segregation is a pre-requisite for preserving genome integrity. Cohesin helps to ensure faithful chromosome segregation during cell cycle, however, much evidence regarding its functions have come to light over the last few years and suggest that cohesin plays multiple roles in the maintenance of genome stability. Here we review our rapidly increasing knowledge on the involvement of cohesin pathway in genome stability and cancer.

Stathmin: a protein with many tasks. New biomarker and potential target in cancer

INTRODUCTION

Stathmin is a microtubule-destabilizing phosphoprotein, firstly identified as the downstream target of many signal transduction pathways. Several studies then indicated that stathmin is overexpressed in many types of human malignancies, thus deserving the name of Oncoprotein 18 (Op18). At molecular level, stathmin depolymerizes microtubules by either sequestering free tubulin dimers or directly inducing microtubule-catastrophe. A crucial role for stathmin in the control of mitosis has been proposed, since both its overexpression and its downregulation induce failure in the correct completion of cell division. Accordingly, stathmin is an important target of the main regulator of M phase, cyclin-dependent kinase 1.

AREAS COVERED

Recent evidences support a role for stathmin in the regulation of cell growth and motility, both in vitro and in vivo, and indicate its involvement in advanced, invasive and metastatic cancer more than in primary tumors.

EXPERT OPINION

Many studies suggest that high stathmin expression levels in cancer negatively influence the response to microtubule-targeting drugs. These notions together with the fact that stathmin is expressed at very low levels in most adult tissues strongly support the use of stathmin as marker of prognosis and as target for novel anti-tumoral and anti-metastatic therapies.

Emerging biomarkers in breast cancer care

Currently, decision-making for breast cancer treatment in the clinical setting is mainly based on clinical data, histomorphological features of the tumor tissue and a few cancer biomarkers such as steroid hormone receptor status (estrogen and progesterone receptors) and oncoprotein HER2 status. Although various therapeutic options were introduced into the clinic in recent decades, with the objective of improving surgery, radiotherapy, biochemotherapy and chemotherapy, varying response of individual patients to certain types of therapy and therapy resistance is still a challenge in breast cancer care. Therefore, since breast cancer treatment should be based on individual features of the patient and her tumor, tailored therapy should be an option by integrating cancer biomarkers to define patients at risk and to reliably predict their course of the disease and/or response to cancer therapy. Recently, candidate-marker approaches and genome-wide transcriptomic and epigenetic screening of different breast cancer tissues and bodily fluids resulted in new promising biomarker panels, allowing breast cancer prognosis, prediction of therapy response and monitoring of therapy efficacy. These biomarkers are now subject of validation in prospective clinical trials.

The expanding universe of cohesin functions: a new genome stability caretaker involved in human disease and cancer

Cohesin is responsible for sister chromatid cohesion, ensuring the correct chromosome segregation. Beyond this role, cohesin and regulatory cohesin genes seem to play a role in preserving genome stability and gene transcription regulation. DNA damage is thought to be a major culprit for many human diseases, including cancer. Our present knowledge of the molecular basis underlying genome instability is extremely limited. Mutations in cohesin genes cause human diseases such as Cornelia de Lange syndrome and Roberts syndrome/SC phocomelia, and all the cell lines derived from affected patients show genome instability. Cohesin mutations have also been identified in colorectal cancer. Here, we will discuss the human disorders caused by alterations of cohesin function, with emphasis on the emerging role of cohesin as a genome stability caretaker.

Associations between single nucleotide polymorphisms in double-stranded DNA repair pathway genes and familial breast cancer

PURPOSE

DNA damage recognition and repair play a major role in risk for breast cancer. We investigated 104 single nucleotide polymorphisms (SNP) in 17 genes whose protein products are involved in double-stranded break repair (DSBR).

EXPERIMENTAL DESIGN

We used a case-control design. Both the case individuals affected with breast cancer or with both breast and ovarian cancers and the controls had similar familial risk of breast cancer and were participants in a high-risk cancer registry.

RESULTS

We found that 12 of the polymorphisms are associated with breast or breast and ovarian cancers, most notably rs16888927, rs16888997, and rs16889040, found in introns of RAD21, suggesting that SNPs in other genes in the DSBR pathway in addition to BRCA1 and BRCA2 may affect breast cancer risk.

CONCLUSIONS

SNPs within or near several DSBR DNA repair pathway genes are associated with breast cancer in individuals from a high-risk population. In addition, our study reemphasizes the unique perspective that recruitment of cases and controls from family cancer registries has for gene discovery studies.

TCEB1 promotes invasion of prostate cancer cells

Amplification of the long arm of chromosome 8 is one of the most recurrent findings in prostate cancer and it is associated with poor prognosis. Several minimal regions of amplification suggest multiple target genes which are yet to be identified. We have previously shown that TCEB1, EIF3S3, KIAA0196 and RAD21 are amplified and overexpressed in prostate cancer and they are located in the 8q area. In this study, we examined the functional effects of these genes to prostate cancer cell phenotype. We overexpressed and inhibited the genes by lentivirus mediated overexpression and RNA interference, respectively. shRNA mediated TCEB1 silencing decreased significantly cellular invasion of PC-3 and DU145 cells through Matrigel. TCEB1 silencing reduced the anchorage-independent growth of PC-3 cells. Similar effects were not seen with any other genes. When overexpressed in NIH 3T3 cells, TCEB1 and EIF3S3 increased the growth rate of the cells. Transcriptional profiling of TCEB1 silenced PC-3 cells revealed decrease of genes involved in invasion and metastasis. Finally, we also confirmed here the overexpression of TCEB1 in hormone-refractory prostate tumors. This study indicates that TCEB1 promotes invasion of prostate cancer cells, is involved in development of hormone-refractory prostate cancer and is thereby a strong candidate to be one of the target genes for the 8q gain.

Stathmin 1: a novel therapeutic target for anticancer activity

Stathmin 1 (STMN1), also known as p17, p18, p19, 19K, metablastin, oncoprotein 18, LAP 18 and Op18, is a 19 kDa cytosolic protein. It was the first discovered member of a family of phylogenetically related microtubule-destabilizing phosphoproteins critically involved in the construction and function of the mitotic spindle. A threshold level of STMN1 is required for orderly progression through mitosis in a variety of cell types. STMN1 is overexpressed across a broad range of human malignancies (leukemia, lymphoma, neuroblastoma; ovarian, prostatic, breast and lung cancers and mesothelioma). It is also upregulated in normally proliferating cell lines but is only rarely upregulated in nonproliferating cell lines with the exception of neurons, anterior pituitary cells and glial cells. Its expression is also upregulated in hepatocytes during regeneration and in lymphoid cells when they are signaled to proliferate. In this review, we summarize available data as rationale for the therapeutic manipulation of STMN1 in cancer patients.

Identification of the molecular mechanisms for dedifferentiation at the invasion front of colorectal cancer by a gene expression analysis

PURPOSE

The aim of this study is to identify gene expression signatures that accompany dedifferentiation at the cancer invasion front in colorectal cancer.

EXPERIMENTAL DESIGN

Two types of colorectal cancer were selected. Both types were well-differentiated adenocarcinomas at the superficial lesion. One type showed a dedifferentiated phenotype at the invasion front (type A, 13 samples); the other showed almost no dedifferentiated cancer cells at the invasion front (type B, 12 samples). Laser microdissection was combined with a cDNA microarray analysis to investigate the superficial lesions and the invasion front in colorectal cancers.

RESULTS

Eighty-three genes were differentially expressed between types A and B in the superficial lesions, and the samples of superficial lesions were divided correctly into two clusters by these genes. Interestingly, the samples of the invasion front were also divided into the two same clusters by these genes. The text mining method selected 10 genes involved in potential mechanisms causing dedifferentiation of cancer cells at the invasion front. The potential mechanisms include the networks of transforming growth factor-beta, Wnt, and Hedgehog signals. The expression levels of 10 genes were calculated by quantitative reverse transcription-PCR and 8 genes were confirmed to be significantly differentially expressed between two types (P < 0.05). The gene expression profiles of 8 genes divided 12 test cases into two clusters with one misclassification.

CONCLUSIONS

The molecular mechanisms constructed with 8 genes from three networks of transforming growth factor-beta, Wnt, and Hedgehog signals were found to correlate with dedifferentiation at the invasion front of colorectal cancer.

Wnt signaling pathway in invasive ductal carcinoma of the breast: relationship between beta-catenin, dishevelled and cyclin D1 expression

OBJECTIVE

The Wnt/beta-catenin signaling cascade is an important signal transduction pathway in human cancers. Overexpression of beta-catenin and its downstream effector, cyclin D1, is implicated in malignant transformation and acquisition of an invasive tumor phenotype. This study aimed to determine the clinical significance of Wnt/beta-catenin canonical pathway components in breast cancer.

METHODS

Expression of beta-catenin, dishevelled (Dvl) and cyclin D1 was examined in invasive ductal carcinomas (IDCs) of the breast by immunohistochemical analysis.

RESULTS

Of the 98 IDCs analyzed, 30% of tumors displayed both nuclear and cytoplasmic staining of Dvl protein, while 52% showed nuclear localization. Loss of cell surface beta-catenin was observed in 66% of breast carcinomas, whereas nuclear expression was observed in 48% IDCs. Cyclin D1 overexpression was observed in 60% IDCs; 31/59 (53%) of these tumors showed nuclear expression of beta-catenin, suggesting upregulation of the canonical Wnt/beta-catenin pathway. Our study demonstrates a significant association between nuclear localization of Dvl and beta-catenin (p < 0.01, OR = 15.8).

CONCLUSION

To our knowledge, this is the first study showing an association between nuclear localization of Dvl and beta-catenin in IDCs and suggests the upregulation of Wnt/beta-catenin pathway components, beta-catenin, Dvl and cyclin D1 in IDCs of the breast.

Prediction of metastatic relapse in node-positive breast cancer: establishment of a clinicogenomic model after FEC100 adjuvant regimen

Breast cancer is a very heterogeneous disease, and markers for disease subtypes and therapy response remain poorly defined. For that reason, we employed a retrospective study in node-positive breast cancer to identify molecular signatures of gene expression correlating with metastatic free survival. Patients were primarily included in FEC100 (5-fluorouracil 500 mg/m(2), epirubicin 100 mg/m(2) and cyclophosphamide 500 mg/m(2)) arms of two multicentric prospective adjuvant clinical trials (PACS01 and PEGASE01-FNCLCC cooperative group). Data from nylon microarrays containing 8,032 cDNA unique sequences, representing 5,776 distinct genes, have been used to develop a predictive model for treatment outcome. We obtained the gene expression profiles for 150 of these patients, and used stringent univariate selection techniques based on Cox regression combined with principal component analysis to identify a genomic signature of metastatic relapse after adjuvant FEC100 regimen. Most of the 14 selected genes have a clear role in breast cancer, carcinogenesis or chemotherapy resistance. Six genes have been previously described in other genomic studies (UBE2C, CENPF, C16orf61 [DC13], STMN1, CCT5 and BCL2A1). Furthermore, we showed the interest of combining transcriptomic data with clinical data into a clinicogenomic model for patients subtyping. The described model adds predictive accuracy to that provided by the well-established Nottingham prognostic index or by our genomic signature alone.