Lung cancers detected by screening with spiral computed tomography have a malignant phenotype when analyzed by cDNA microarray

The Potential of Stem Cells in Treating Breast Cancer

There has been a lot of interest in stem cell therapy as a means of curing disease in recent years. Despite extensive usage of stem cell therapy in the treatment of a wide range of medical diseases, it has been hypothesized that it plays a key part in the progression of cancer. Breast cancer is still the most frequent malignancy in women globally. However, the latest treatments, such as stem cell targeted therapy, are considered to be more effective in preventing recurrence, metastasis, and chemoresistance of breast cancer than older methods like chemotherapy and radiation. This review discusses the characteristics of stem cells and how stem cells may be used to treat breast cancer.

Unusual Suspects: Bone and Cartilage ECM Proteins as Carcinoma Facilitators

The extracellular matrix (ECM) is the complex three-dimensional network of fibrous proteins and proteoglycans that constitutes an essential part of every tissue to provide support for normal tissue homeostasis. Tissue specificity of the ECM in its topology and structure supports unique biochemical and mechanical properties of each organ. Cancers, like normal tissues, require the ECM to maintain multiple processes governing tumor development, progression and spread. A large body of experimental and clinical evidence has now accumulated to demonstrate essential roles of numerous ECM components in all cancer types. Latest findings also suggest that multiple tumor types express, and use to their advantage, atypical ECM components that are not found in the cancer tissue of origin. However, the understanding of cancer-specific expression patterns of these ECM proteins and their exact roles in selected tumor types is still sketchy. In this review, we summarize the latest data on the aberrant expression of bone and cartilage ECM proteins in epithelial cancers and their specific functions in the pathogenesis of carcinomas and discuss future directions in exploring the utility of this selective group of ECM components as future drug targets.

New insights into vitamin K biology with relevance to cancer

Phylloquinone (vitamin K1) and menaquinones (vitamin K2 family) are essential for post-translational γ-carboxylation of a small number of proteins, including clotting factors. These modified proteins have now been implicated in diverse physiological and pathological processes including cancer. Vitamin K intake has been inversely associated with cancer incidence and mortality in observational studies. Newly discovered functions of vitamin K in cancer cells include activation of the steroid and xenobiotic receptor (SXR) and regulation of oxidative stress, apoptosis, and autophagy. We provide an update of vitamin K biology, non-canonical mechanisms of vitamin K actions, the potential functions of vitamin K-dependent proteins in cancer, and observational trials on vitamin K intake and cancer.

Analysis of lung cancer-related genetic changes in long-term and low-dose polyhexamethylene guanidine phosphate (PHMG-p) treated human pulmonary alveolar epithelial cells

BACKGROUND

Lung injury elicited by respiratory exposure to humidifier disinfectants (HDs) is known as HD-associated lung injury (HDLI). Current elucidation of the molecular mechanisms related to HDLI is mostly restricted to fibrotic and inflammatory lung diseases. In our previous report, we found that lung tumors were caused by intratracheal instillation of polyhexamethylene guanidine phosphate (PHMG-p) in a rat model. However, the lung cancer-related genetic changes concomitant with the development of these lung tumors have not yet been fully defined. We aimed to discover the effect of long-term exposure of PHMG-p on normal human lung alveolar cells.

METHODS

We investigated whether PHMG-p could increase distorted homeostasis of oncogenes and tumor-suppressor genes, with long-term and low-dose treatment, in human pulmonary alveolar epithelial cells (HPAEpiCs). Total RNA sequencing was performed with cells continuously treated with PHMG-p and harvested after 35 days.

RESULTS

After PHMG-p treatment, genes with transcriptional expression changes of more than 2.0-fold or less than 0.5-fold were identified. Within 10 days of exposure, 2 protein-coding and 5 non-coding genes were selected, whereas in the group treated for 27-35 days, 24 protein-coding and 5 non-coding genes were identified. Furthermore, in the long-term treatment group, 11 of the 15 upregulated genes and 9 of the 14 downregulated genes were reported as oncogenes and tumor suppressor genes in lung cancer, respectively. We also found that 10 genes of the selected 24 protein-coding genes were clinically significant in lung adenocarcinoma patients.

CONCLUSIONS

Our findings demonstrate that long-term exposure of human pulmonary normal alveolar cells to low-dose PHMG-p caused genetic changes, mainly in lung cancer-associated genes, in a time-dependent manner.

Host-Parasite Interaction of Atlantic salmon (Salmo salar) and the Ectoparasite Neoparamoeba perurans in Amoebic Gill Disease

Marine farmed Atlantic salmon (Salmo salar) are susceptible to recurrent amoebic gill disease (AGD) caused by the ectoparasite Neoparamoeba perurans over the growout production cycle. The parasite elicits a highly localized response within the gill epithelium resulting in multifocal mucoid patches at the site of parasite attachment. This host-parasite response drives a complex immune reaction, which remains poorly understood. To generate a model for host-parasite interaction during pathogenesis of AGD in Atlantic salmon the local (gill) and systemic transcriptomic response in the host, and the parasite during AGD pathogenesis was explored. A dual RNA-seq approach together with differential gene expression and system-wide statistical analyses of gene and transcription factor networks was employed. A multi-tissue transcriptomic data set was generated from the gill (including both lesioned and non-lesioned tissue), head kidney and spleen tissues naïve and AGD-affected Atlantic salmon sourced from an in vivo AGD challenge trial. Differential gene expression of the salmon host indicates local and systemic upregulation of defense and immune responses. Two transcription factors, znfOZF-like and znf70-like, and their associated gene networks significantly altered with disease state. The majority of genes in these networks are candidates for mediators of the immune response, cellular proliferation and invasion. These include Aurora kinase B-like, rho guanine nucleotide exchange factor 25-like and protein NDNF-like inhibited. Analysis of the N. perurans transcriptome during AGD pathology compared to in vitro cultured N. perurans trophozoites, as a proxy for wild type trophozoites, identified multiple gene candidates for virulence and indicates a potential master regulatory gene system analogous to the two-component PhoP/Q system. Candidate genes identified are associated with invasion of host tissue, evasion of host defense mechanisms and formation of the mucoid lesion. We generated a novel model for host-parasite interaction during AGD pathogenesis through integration of host and parasite functional profiles. Collectively, this dual transcriptomic study provides novel molecular insights into the pathology of AGD and provides alternative theories for future research in a step towards improved management of AGD.

Deletion of Krüppel-like factor-4 promotes axonal regeneration in mammals

Axonal regeneration plays an important role in functional recovery after nervous system damage. However, after axonal injury in mammals, regeneration is often poor. The deletion of Krüppel-like factor-4 (Klf4) has been shown to promote axonal regeneration in retinal ganglion cells. However, the effects of Klf4 deletion on the corticospinal tract and peripheral nervous system are unknown. In this study, using a mouse model of sciatic nerve injury, we show that the expression of Klf4 in dorsal root ganglion sensory neurons was significantly reduced after peripheral axotomy, suggesting that the regeneration of the sciatic nerve is associated with Klf4. In vitro, dorsal root ganglion sensory neurons with Klf4 knockout exhibited significantly enhanced axonal regeneration. Furthermore, the regeneration of the sciatic nerve was enhanced in vivo following Klf4 knockout. Finally, AAV-Cre virus was used to knockout the Klf4 gene in the cortex. The deletion of Klf4 enhanced regeneration of the corticospinal tract in mice with spinal cord injury. Together, our findings suggest that regulating KLF4 activity in neurons is a potential strategy for promoting axonal regeneration and functional recovery after nervous system injury. This study was approved by the Animal Ethics Committee at Soochow University, China (approval No. SUDA20200316A01).

Intracellular matrix Gla protein promotes tumor progression by activating JAK2/STAT5 signaling in gastric cancer

Matrix Gla protein (MGP) has been widely reported as an extracellular matrix protein with abnormal expression in various types of cancer. However, the function of intracellular MGP in gastric cancer (GC) cells remains largely unknown. Here, we demonstrated aberrantly high expression of intracellular MGP in GC as compared to adjacent normal tissues by immunohistochemistry. Moreover, The Cancer Genome Atlas (TCGA) dataset analysis suggested a positive correlation between MGP overexpression and unfavorable prognosis. MGP silencing reduced cell proliferation, migration, invasion, and survival in GC cell lines. Gene set enrichment analysis of TCGA dataset indicated significant enrichment of the IL2-STAT5 signaling in MGP-high GC patients. Immunofluorescence staining and immunoprecipitation showed that MGP binds to p-STAT5 in the nuclei of GC cells. Furthermore, ChIP-qPCR and luciferase reporter assays indicated that MGP acts as a transcriptional co-activator through the enhancement of STAT5 binding to target gene promoters. Use of STAT5 inhibitor revealed that the oncogenic functions of intracellular MGP mainly depend on the JAK2/STAT5 signaling pathway. Taken together, our results indicate that intracellular MGP promotes proliferation and survival of GC cells by acting as a transcriptional co-activator of STAT5. The detected aberrant, high MGP expression in GC tissues highlights MGP as a potential new prognostic biomarker in patients with GC.

Targeting cancer stem cell pathways for cancer therapy

Since cancer stem cells (CSCs) were first identified in leukemia in 1994, they have been considered promising therapeutic targets for cancer therapy. These cells have self-renewal capacity and differentiation potential and contribute to multiple tumor malignancies, such as recurrence, metastasis, heterogeneity, multidrug resistance, and radiation resistance. The biological activities of CSCs are regulated by several pluripotent transcription factors, such as OCT4, Sox2, Nanog, KLF4, and MYC. In addition, many intracellular signaling pathways, such as Wnt, NF-κB (nuclear factor-κB), Notch, Hedgehog, JAK-STAT (Janus kinase/signal transducers and activators of transcription), PI3K/AKT/mTOR (phosphoinositide 3-kinase/AKT/mammalian target of rapamycin), TGF (transforming growth factor)/SMAD, and PPAR (peroxisome proliferator-activated receptor), as well as extracellular factors, such as vascular niches, hypoxia, tumor-associated macrophages, cancer-associated fibroblasts, cancer-associated mesenchymal stem cells, extracellular matrix, and exosomes, have been shown to be very important regulators of CSCs. Molecules, vaccines, antibodies, and CAR-T (chimeric antigen receptor T cell) cells have been developed to specifically target CSCs, and some of these factors are already undergoing clinical trials. This review summarizes the characterization and identification of CSCs, depicts major factors and pathways that regulate CSC development, and discusses potential targeted therapy for CSCs.

Single-cell RNA sequencing reveals novel gene expression signatures of trastuzumab treatment in HER2+ breast cancer: A pilot study

Human epidermal growth factor receptor 2-positive (HER2+) breast cancer accounts for ∼20% of invasive breast cancers and is associated with poor prognostics. The recent outcome of HER2+ breast cancer treatment has been vastly improved owing to the application of antibody-targeted therapies. Trastuzumab (Herceptin) is a monoclonal antibody designed to target HER2+ breast cancer cells. In addition to improved survival in the adjuvant treatment of HER2+ breast cancer, trastuzumab treatment has also been associated with cardiotoxicity side effect. However, the molecular mechanisms of trastuzumab action and trastuzumab-mediated cardiotoxicity are still not fully understood. Previous research utilized bulk transcriptomics analysis to study the underlining mechanisms, which relied on averaging molecular signals from bulk tumor samples and might have overlooked key expression features within breast cancer tumor. In contrast to previous research, we compared the single cancer cell level transcriptome profile between trastuzumab-treated and nontreated patients to reveal a more in-depth transcriptome profile. A total of 461 significantly differential expressed genes were identified, including previously defined and novel gene expression signatures. In addition, we found that trastuzumab-enhanced MGP gene expression could be used as prognostics marker for longer patient survival in breast invasive carcinoma patients, and validated our finding using TCGA (The Cancer Genome Atlas) breast cancer dataset. Moreover, our study revealed a 48-gene expression signature that is associated with cell death of cardiomyocytes, which could be used as early biomarkers for trastuzumab-mediated cardiotoxicity. This work is the first study to look at single cell level transcriptome profile of trastuzumab-treated patients, providing a new understanding of the molecular mechanism(s) of trastuzumab action and trastuzumab-induced cardiotoxicity side effects.

A novel molecular and clinical staging model to predict survival for patients with esophageal squamous cell carcinoma

Current prognostic factors fail to accurately determine prognosis for patients with esophageal squamous cell carcinoma (ESCC) after surgery. Here, we constructed a survival prediction model for prognostication in patients with ESCC. Candidate molecular biomarkers were extracted from the Gene Expression Omnibus (GEO), and Cox regression analysis was performed to determine significant prognostic factors. The survival prediction model was constructed based on cluster and discriminant analyses in a training cohort (N=205), and validated in a test cohort (N=207). The survival prediction model consisting of two genes (UBE2C and MGP) and two clinicopathological factors (tumor stage and grade) was developed. This model could be used to accurately categorize patients into three groups in the test cohort. Both disease-free survival and overall survival differed among the diverse groups (P<0.05). In summary, we have developed and validated a predictive model that is based on two gene markers in conjunction with two clinicopathological variables, and which can accurately predict outcomes for ESCC patients after surgery.

Cystatin A suppresses tumor cell growth through inhibiting epithelial to mesenchymal transition in human lung cancer

Cystatin A (CSTA), belonging to type 1 cystatin super-family, is expressed primarily in epithelial and lymphoid tissues for protecting cells from proteolysis of cytoplasmic and cytoskeletal proteins by cathepsins B, H and L. CSTA acts as a tumor suppressor in esophageal cancer, however, its role in lung cancer has not yet been elucidated. Here we found that CSTA was down-regulated in all lung cancer cell lines compared to normal lung epithelial cells. CSTA was restored in most lung cancer cell lines after treatment with demethylation agent 5-aza-2-deoxycytidine and deacetylation agent Trichostatin. Bisulfite sequencing revealed that CSTA was partially methylated in the promoter and exon 1. In primary lung tumors, squamous cell carcinoma (SCC) significantly expressed more CSTA compared to adenocarcinoma (p<0.00001), and higher expression of CSTA was significantly associated with lower tumor grade (p<0.01). CSTA stable transfection reduced the activity of cathepsin B and inhibited the ability of colony formation, migration and invasion, and enhanced gemcitabine-induced apoptosis. CSTA overexpression resulted in reduced activity of ERK, p-38, and AKT. Additionally, CSTA overexpression led to a mesenchymal to epithelial transition (MET) and prevented the TGF-β1-induced epithelial to mesenchymal transition (EMT) through inhibiting the ERK/MAPK pathway. In conclusion, our date indicate 1) epigenetic regulation is associated with CSTA gene silencing; 2) CSTA exerts tumor suppressive function through inhibiting MAPK and AKT pathways; 3) Overexpression of CSTA leads to MET and prevents TGF-β1-induced EMT by modulating the MAPK pathway; 4) CSTA may be a potential biomarker for lung SCC and tumor differentiation.

Matrix Gla protein in tumoral pathology

Matrix Gla protein is a vitamin K-dependent protein secreted by chondrocytes and vascular smooth muscle cells. The presence of matrix Gla protein was reported in arterial and venous walls, lungs, kidney, uterus, heart, tooth cementum and eyes. Several studies identified matrix Gla protein in tumoral pathology.

Until recently, it was thought to only have an inhibitory role of physiological and ectopic calcification. New studies demonstrated that it also has a role in physiological and pathological angiogenesis, as well as in tumorigenesis.

The aim of this review is to report the latest findings related to the expression and clinical implications of matrix Gla protein in different types of cancer with an emphasis on cerebral tumors.

Relationship between KLF4 and primary hepatocellular carcinoma

Kruppel-like factors (KLFs) are a family of transcription factors with zinc finger structure, which play a key role in cell proliferation, apoptosis, differentiation and embryonic development. KLF4 is an important member of the KLF family, and it is highly expressed in primary hepatocellular carcinoma tissues. However, the mechanism of KLF4 in primary hepatocellular carcinoma remains to be explored. This paper reviews the biological function of KLF4 in primary hepatocellular carcinoma.

Gene Signatures Stratify Computed Tomography Screening Detected Lung Cancer in High-Risk Populations

BACKGROUND

Although screening programmes of smokers have detected resectable early lung cancers more frequently than expected, their efficacy in reducing mortality remains debatable. To elucidate the biological features of computed tomography (CT) screening detected lung cancer, we examined the mRNA signatures on tumours according to the year of detection, stage and survival.

METHODS

Gene expression profiles were analysed on 28 patients (INT-IEO training cohort) and 24 patients of Multicentre Italian Lung Detection (MILD validation cohort). The gene signatures generated from the training set were validated on the MILD set and a public deposited DNA microarray data set (GSE11969). Expression of selected genes and proteins was validated by real-time RT-PCR and immunohistochemistry. Enriched core pathway and pathway networks were explored by GeneSpring GX10.

FINDINGS

A 239-gene signature was identified according to the year of tumour detection in the training INT-IEO set and correlated with the patients' outcomes. These signatures divided the MILD patients into two distinct survival groups independently of tumour stage, size, histopathological type and screening year. The signatures can also predict survival in the clinically detected cancers (GSE11969). Pathway analyses revealed tumours detected in later years enrichment of the PI3K/PTEN/AKT pathway, with up-regulation of PDPK1, ITGB1 and down-regulation of FOXO1A. Analysis of normal lung tissue from INT-IEO cohort produced signatures distinguishing patients with early from late detected tumours.

INTERPRETATION

The distinct pattern of "indolent" and "aggressive" tumour exists in CT-screening detected lung cancer according to the gene expression profiles. The early development of an aggressive phenotype may account for the lack of mortality reduction by screening observed in some cohorts.

Whole exome sequencing identifies driver mutations in asymptomatic computed tomography-detected lung cancers with normal karyotype

The efficacy of curative surgery for lung cancer could be largely improved by non-invasive screening programs, which can detect the disease at early stages. We previously showed that 18% of screening-identified lung cancers demonstrate a normal karyotype and, following high-density genome scanning, can be subdivided into samples with 1) numerous; 2) none; and 3) few copy number alterations. Whole exome sequencing was applied to the two normal karyotype, screening-detected lung cancers, constituting group 2, as well as normal controls. We identified mutations in both tumors, including KEAP1 (commonly mutated in lung cancers) in one, and TP53, PMS1, and MSH3 (well-characterized DNA-repair genes) in the other. The two normal karyotype screening-detected lung tumors displayed a typical lung cancer mutational profile that only next generation sequencing could reveal, which offered an additional contribution to the over-diagnosis bias concept hypothesized within lung cancer screening programs.

Lung cancer screening: the European perspective

European studies have contributed significantly to the understanding of lung cancer screening. Smoking within screening, quality of life, nodule management, minimally invasive treatments, cancer prevention programs, and risk models have been extensively investigated by European groups. Mortality data from European screening studies have not been encouraging so far, but long-term results of the NELSON study are eagerly awaited. Investigations on molecular markers of lung cancer are ongoing in Europe; preliminary results suggest they may become an important screening tool in the future.

Caveolin and cavin family members: dual roles in cancer

Caveolae are specialized plasma membrane subdomains with distinct lipid and protein compositions, which play an essential role in cell physiology through regulation of trafficking and signaling functions. The structure and functions of caveolae have been shown to require the proteins caveolins. Recently, members of the cavin protein family were found to be required, in concert with caveolins, for the formation and function of caveolae. Caveolins have a paradoxical role in the development of cancer formation. They have been involved in both tumor suppression and oncogenesis, depending on tumor type and progress stage. High expression of caveolins and cavins leads to inhibition of cancer-related pathways, such as growth factor signaling pathways. However, certain cancer cells that express caveolins and cavins have been shown to be more aggressive and metastatic because of their increased potential for anchorage-independent growth. Here, we will survey the functional roles of caveolins and of different cavin family members in cancer regulation.

MiR-7 promotes epithelial cell transformation by targeting the tumor suppressor KLF4

MicroRNAs (miRNAs) are endogenous small non-coding RNAs that have a pivotal role in the post-transcriptional regulation of gene expression and their misregulation is common in different types of cancer. Although it has been shown that miR-7 plays an oncogenic role in different cellular contexts, the molecular mechanisms by which miR-7 promotes cell transformation are not well understood. Here we show that the transcription factor KLF4 is a direct target of miR-7 and present experimental evidence indicating that the regulation of KLF4 by miR-7 has functional implications in epithelial cell transformation. Stable overexpression of miR-7 into lung and skin epithelial cells enhanced cell proliferation, cell migration and tumor formation. Alteration of these cellular functions by miR-7 resulted from misregulation of KLF4 target genes involved in cell cycle control. miR-7-induced tumors showed decreased p21 and increased Cyclin D levels. Taken together, these findings indicate that miR-7 acts as an oncomiR in epithelial cells in part by directly regulating KLF4 expression. Thus, we conclude that miR-7 acts as an oncomiR in the epithelial cellular context, where through the negative regulation of KLF4-dependent signaling pathways, miR-7 promotes cellular transformation and tumor growth.

Allograft inflammatory factor-1 is an independent prognostic indicator that regulates β-catenin in gastric cancer

Previous studies have revealed that expression of allograft inflammatory factor-1 (AIF-1) protein appears to be increased in malignancies and is correlated with a poorer prognosis in cervical cancer, while its role in gastric cancer has not been reported. We analyzed the expression of AIF-1 in 78 cancer lesions and the corresponding non-cancerous tissues by immunohistochemistry. In contrast with other cancers, we found that AIF-1 protein levels were significantly decreased in 53 of the 78 (67.9%) gastric cancer tissues when compared with the matched normal tissues. This was further confirmed using 7 pairs of fresh gastric cancer tissues and matched adjacent normal tissues. Low tumoral AIF-1 expression was significantly correlated with less favorable clinicopathological characteristics, as well as with reduced overall survival (P<0.001) in the gastric cancer patients. Furthermore, knockdown of AIF-1 obviously increased proliferation, migration and β-catenin expression in BGC-823 and SGC-7901 gastric cancer cells. Taken together, for the first time, we provide evidence that the level of AIF-1 expression may serve as a protective prognostic indicator for gastric cancer.

Current status of lung cancer screening

Low-dose CT (LDCT) is effective in the early detection of lung cancer, providing higher resectability and long-term survival rates. The National Lung Screening Trial shows a statistically significant mortality reduction in LDCT compared with chest radiography. The efficacy and safety of annual LDCT screening in heavy smokers must be explored, and the magnitude of benefit compared with the cost of large-scale screening. Trials in Europe have different study designs and an observational arm. Strategies to reduce lung cancer mortality should combine early detection with primary prevention and innovative biologic approaches.

Loss of epigenetic Kruppel-like factor 4 histone deacetylase (KLF-4-HDAC)-mediated transcriptional suppression is crucial in increasing vascular endothelial growth factor (VEGF) expression in breast cancer

Vascular endothelial growth factor (VEGF) is recognized as an important angiogenic factor that promotes angiogenesis in a series of pathological conditions, including cancer, inflammation, and ischemic disorders. We have recently shown that the inflammatory transcription factor SAF-1 is, at least in part, responsible for the marked increase of VEGF levels in breast cancer. Here, we show that SAF-1-mediated induction of VEGF is repressed by KLF-4 transcription factor. KLF-4 is abundantly present in normal breast epithelial cells, but its level is considerably reduced in breast cancer cells and clinical cancer tissues. In the human VEGF promoter, SAF-1- and KLF-4-binding elements are overlapping, whereas SAF-1 induces and KLF-4 suppresses VEGF expression. Ectopic overexpression of KLF-4 and RNAi-mediated inhibition of endogenous KLF-4 supported the role of KLF-4 as a transcriptional repressor of VEGF and an inhibitor of angiogenesis in breast cancer cells. We show that KLF-4 recruits histone deacetylases (HDACs) -2 and -3 at the VEGF promoter. Chronological ChIP assays demonstrated the occupancy of KLF-4, HDAC2, and HDAC3 in the VEGF promoter in normal MCF-10A cells but not in MDA-MB-231 cancer cells. Co-transfection of KLF-4 and HDAC expression plasmids in breast cancer cells results in synergistic repression of VEGF expression and inhibition of angiogenic potential of these carcinoma cells. Together these results identify a new mechanism of VEGF up-regulation in cancer that involves concomitant loss of KLF-4-HDAC-mediated transcriptional repression and active recruitment of SAF-1-mediated transcriptional activation.

Overexpression of ERα inhibits proliferation and invasion of MKN28 gastric cancer cells by suppressing β-catenin

The relationship between estrogen receptor (ER)α and patient prognosis has been identified in gastric cancer; however, the definite role of ERα in gastric cancer remains to be fully elucidated. The aim of the present in vitro study was to investigate the impact of ERα on cell proliferation, migration and invasion in gastric cancer cell lines. We investigated the biological effect of ERα overexpression on gastric carcinoma cells. An MKN28 gastric cancer cell line stably overexpressing ERα was established. The effect of ERα overexpression on cell growth was assessed by evaluating cell survival, colony formation, cell cycle progression and apoptosis. Cell migration and invasion were detected by Transwell migration/invasion assays. The protein levels of several potentially involved genes were determined by western blotting to elucidate the underlying molecular mechanisms. The Student's t-test was used to determine the statistical differences between various experimental and control groups, and one-way ANOVA test was used to determine the difference between three or more groups. The results showed that ERα overexpression significantly inhibited cell growth and proliferation, blocked cell entry into the G1/G0 phase and promoted cell apoptosis. In addition, ERα reduced the motility and invasion of gastric cancer cells. These phenotypes may partly be explained by a decrease in β-catenin expression caused by ERα overexpression. ERα overexpression effectively inhibited cell growth and cancer progression by suppressing β-catenin in gastric cancer, identifying ERα as a promising target with therapeutic potential for development of new approaches to treat gastric cancer.

Altered expression of Krüppel-like factor 4 and β-catenin in human gastric cancer

The effects of the interaction between KLF4 and β-catenin may be significant in human carcinogenesis and tumor development. This study aimed to determine whether the expression of KLF4 and β-catenin in gastric cancer tissues is associated with clinicopathological characteristics. Western blot analysis and immunohistochemistry were performed to detect KLF4 and β-catenin expression in tumor and corresponding non-cancerous tissues from 49 patients. The data revealed that KLF4 expression was significantly reduced in gastric cancer tissues compared with normal tissues. By contrast, the expression of the β-catenin protein was significantly increased in all tumor tissues, but was not expressed in distant normal mucosae. The altered expression of the KLF4 and β-catenin proteins was associated with advanced tumor stage and gastric cancer. In addition, the expression of the KLF4 and β-catenin proteins was inversely associated in moderately differentiated human gastric cancers. This study showed that β-catenin expression is significantly increased and KLF4 protein expression is markedly decreased in gastric cancer tissues, thus showing that the expression of KLF4 is inversely correlated with that of β-catenin in gastric cancer. The altered expression of the two proteins is associated with advanced tumor stage in gastric cancer.

Modulation of cystatin A expression in human airway epithelium related to genotype, smoking, COPD, and lung cancer

The cathepsin inhibitor Cystatin A (CSTA) has antiapoptotic properties linked with neoplastic changes in squamous cell epithelium, where it has been proposed as a diagnostic and prognostic marker of lung cancer. Notably, cystatin A is upregulated in dysplastic epithelium, prompting us to hypothesize that it might be modulated in chronic obstructive pulmonary disease (COPD), a small airway epithelial (SAE) disorder that is a risk factor for non-small cell lung cancer (NSCLC) in a subset of smokers. Here we report that genetic variation, smoking, and COPD can all elevate levels of CSTA expression in lung small airway epithelia, with still further upregulation in squamous cell carcinoma (SCC), an NSCLC subtype. We examined SAE gene expression in 178 individuals, including healthy nonsmokers (n = 60), healthy smokers (n = 82), and COPD smokers (n = 36), with corresponding large airway epithelium (LAE) data included in a subset of subjects (n = 52). Blood DNA was genotyped by SNP microarray. Twelve SNPs upstream of the CSTA gene were found to associate with its expression in SAE. Levels were higher in COPD smokers than in healthy smokers, who, in turn, had higher levels than nonsmokers. CSTA gene expression in LAE was also smoking-responsive. Using publicly available NSCLC expression data we also found that CSTA was upregulated in SCC versus LAE and downregulated in adenocarcinoma versus smoke-exposed SAE. All phenotypes were associated with different proportional expression of CSTA to cathepsins. Our findings establish that genetic variability, smoking, and COPD all influence CSTA expression, as does SCC, supporting the concept that CSTA may make pivotal contributions to NSCLC pathogenesis in both early and late stages of disease development.

Prognostic value and function of KLF4 in prostate cancer: RNAa and vector-mediated overexpression identify KLF4 as an inhibitor of tumor cell growth and migration

KLF4/GLKF4 is a transcription factor that can have divergent functions in different malignancies. The role of KLF4 in prostate cancer etiology remains unclear. We have recently reported that small double-stranded RNA can induce gene expression by targeting promoter sequence in a phenomenon referred to as RNA activation (RNAa). In this study, we examine KLF4 levels in prostate cancer tissue and utilize RNAa as a tool for gene overexpression to investigate its function. Expression analysis indicated that KLF4 is significantly downregulated in prostate cancer cell lines compared with nontumorigenic prostate cells. Meta-analysis of existing cDNA microarray data also revealed that KLF4 is frequently depleted in prostate cancer tissue with more pronounced reduction in metastases. In support, tissue microarray analysis of tumors and patient-matched controls indicated downregulation of KLF4 in metastatic tumor samples. Logistic regression analysis found that tumors with a KLF4 staining score less than 5 had a 15-fold higher risk for developing metastatic prostate cancer (P = 0.001; 95% confidence interval, 3.0-79.0). In vitro analysis indicated that RNAa-mediated overexpression of KLF4 inhibited prostate cancer cell proliferation and survival and altered the expression of several downstream cell-cycle-related genes. Ectopic expression of KLF4 via viral transduction recapitulated the RNAa results, validating its inhibitory effects on cancer growth. Reactivation of KLF4 also suppressed migration and invasion of prostate cancer cells. These results suggest that KLF4 functions as an inhibitor of tumor cell growth and migration in prostate cancer and decreased expression has prognostic value for predicting prostate cancer metastasis.

GKLF transfection inhibits the growth of xenograft tumors derived from human gastric carcinoma cell line SGC-7901 in nude mice

AIM: To investigate the effects of transfection of the gut-enriched Krüppel-like factor (GKLF) gene on the growth of xenograft tumors derived from human gastric carcinoma cell line SGC-7901 in nude mice and to explore the potential role of the GKLF gene in gastric carcinogenesis.

METHODS: A recombinant plasmid carrying the GKLF gene (pcDNA3.1-GKLF) was transfected into SGC-7901 cells by lipofectin-mediated method. Cells stably expressing the GKLF gene were selected using G418. SGC-7901 cells untransfected and those transfected with empty pcDNA3.1 plasmid were used as controls. A xenograft tumor model was then established. Tumor growth was monitored. Tumor histopathological changes were determined by hematoxylin and eosin (HE) staining. The expression of GKLF and Ki-67 proteins in xenograft tissue was detected by immunohistochemistry.

RESULTS: Compared with the SGC7901-pcDNA3.1 and SGC-7901 groups, the period of latency was significantly lengthened in the SGC7901-pcDNA3.1-GKLF group (14.67 d ± 3.08 d vs 8.33 d ± 1.03 d, 8.67 d ± 1.03 d, both P < 0.05). The weight of xenograft tumors in the SGC7901-pcDNA3.1-GKLF group was significantly lower than that in the SGC7901-pcDNA3.1 and SGC-7901 groups (4.46 g ± 0.92 g vs 8.05 g ± 1.66 g, 7.82 g ± 1.14 g, both P < 0.05). The degree of tumor differentiation in the SGC7901-pcDNA3.1-GKLF group was better than that in the other two groups. Furthermore, the positive proportion of GKLF protein expression in xenograft tissue was increased while that of Ki-67 protein expression was decreased in the SGC7901-pcDNA3.1-GKLF group when compared with the other two groups (4/6 vs 2/6, 2/6; 1/6 vs 4/6, 4/6).

CONCLUSION: Transfection of the GKLF gene inhibits the growth of subcutaneous xenograft tumors derived from SGC-7901 cell line in nude mice by down-regulating the expression of Ki-67. The GKLF gene is a potential target for gene therapy of gastric carcinoma.

Mammalian Krüppel-like factors in health and diseases

The Krüppel-like factor (KLF) family of transcription factors regulates diverse biological processes that include proliferation, differentiation, growth, development, survival, and responses to external stress. Seventeen mammalian KLFs have been identified, and numerous studies have been published that describe their basic biology and contribution to human diseases. KLF proteins have received much attention because of their involvement in the development and homeostasis of numerous organ systems. KLFs are critical regulators of physiological systems that include the cardiovascular, digestive, respiratory, hematological, and immune systems and are involved in disorders such as obesity, cardiovascular disease, cancer, and inflammatory conditions. Furthermore, KLFs play an important role in reprogramming somatic cells into induced pluripotent stem (iPS) cells and maintaining the pluripotent state of embryonic stem cells. As research on KLF proteins progresses, additional KLF functions and associations with disease are likely to be discovered. Here, we review the current knowledge of KLF proteins and describe common attributes of their biochemical and physiological functions and their pathophysiological roles.

Genomic characterization of asymptomatic CT-detected lung cancers

Computed tomography (CT) screening of lung cancer allows the detection of early tumors. The objective of our study was to verify whether initial asymptomatic lung cancers, identified by high-resolution low-dose CT (LD-CT) on a high-risk population, show genetic abnormalities that could be indicative of the early events of lung carcinogenesis. We analyzed 78 tumor samples: 21 (pilot population) from heavy smokers with asymptomatic non-screening detected early-stage lung cancers and 57 from 5203 asymptomatic heavy smoker volunteers, who underwent a LD-CT screening study. During surgical resection of the detected tumors, tissue samples were collected and short-term cultures were started for karyotype evaluation. Samples were classified according to the normal (NK) or aneuploid (AK) karyotype. The NK samples were further analyzed by the Affymetrix single-nucleotide polymorphisms (SNPs) technology. Metaphase spreads were obtained in 73.0% of the selected samples: 80.7% showed an AK. A statistically significant correlation was found between presence of vascular invasion and abnormal karyotype. A total of 10 NK samples were suitable for SNPs analysis. Subtle genomic alterations were found in eight tumors, the remaining two showing no evidence to date of chromosomal aberrations anywhere in the genome. Two common regions of amplification were identified at 5p and 8p11. Mutation analysis by direct sequencing was conducted for the K-RAS, TP53 and EGFR genes, confirming data already described for heavy smokers. We show that: (i) the majority of screening-detected tumors are aneuploid; (ii) early-stage tumors tend to harbor a less abnormal karyotype; (iii) whole genome analysis of NK tumors allows for the detection of common regions of copy number variation (such as amplifications at 5p and 8p11), highlighting genes that might be considered candidate markers of early events in lung carcinogenesis.

Long-term outcomes of a pilot CT screening for lung cancer

BACKGROUND

Low-dose computed tomography (CT) screening can detect early stage lung cancer in high-risk populations. However, no data on repeated annual screening over more than 5 years are available, and the impact of screening on lung cancer mortality is controversial.

METHODS

We analysed outcomes in high-risk asymptomatic volunteers (smokers and former smokers, >50 years) enrolled in a pilot study over 1 year from June 2000, who received annual low-dose CT for 7 years. Cumulative lung cancer incidence and survival were represented by Kaplan-Meier curves. Standardized incidence and mortality ratios were used to estimate risks relative to the general Italian and US population.

RESULTS

Compliance was 86% at the end of the seventh year in 1035 recruited volunteers (71% men, mean age 58 years). Lung cancer was diagnosed in 54 (5.3%); radical surgery was possible in 48/54 (87%); 39/54 (72%) had stage I disease. Five-year survival was 63% overall, 89% for stage I cases. During 6308 person-years of observation, 47 participants had died versus 75 expected in the Italian general population standardised for age and sex. Fourteen lung cancer deaths were registered versus 27 expected in a standardised US smoker population.

CONCLUSIONS

Seventy percent of screening-diagnosed patients had stage I disease, and the survival of screen-detected cancer patients was high. Lung cancer mortality was favourable compared to age- and sex-matched population of US smokers, suggesting that mortality can be lowered by screening, although larger trials with longer follow-up are necessary to confirm these findings.

MicroRNA-10b promotes migration and invasion through KLF4 in human esophageal cancer cell lines

Recently, microRNAs have emerged as regulators of cancer metastasis through acting on multiple signaling pathways involved in metastasis. In this study, we have analyzed the level of miR-10b and cell motility and invasiveness in several human esophageal squamous cell carcinoma cell lines. Our results reveal a significant correlation of miR-10b level with cell motility and invasiveness. Overexpression of miR-10b in KYSE140 cells increased cell motility and invasiveness, whereas inhibition of miR-10b in EC9706 cells reduced cell invasiveness, although it did not alter cell motility. Additionally, we identified KLF4, a known tumor suppressor gene that has been reported to suppress esophageal cancer cell migration and invasion, as a direct target of miR-10b. Furthermore, overexpression of miR-10b in KYSE140 and KYSE450 cells led to a reduction of endogenous KLF4 protein, whereas silencing of miR-10b in EC9706 cells caused up-regulation of KLF4 protein. Coexpression of miR-10b and KLF4 in KYSE140 cells and coexpression of small interfering RNA for KLF4 mRNA and miR-10b-AS in EC9706 cells partially abrogated the effect of miR-10b on cell migration and invasion. Finally, analyses of the miR-10b level in 40 human esophageal cancer samples and their paired normal adjacent tissues revealed an elevated expression of miR-10b in 95% (38 of 40) of cancer tissues, although no significant correlation of the miR-10b level with clinical metastasis status was observed in these samples.

Plasma DNA quantification in lung cancer computed tomography screening: five-year results of a prospective study

RATIONALE

Free circulating plasma DNA has emerged as a potential biomarker for early lung cancer detection. In a previous case-control study we have shown that high levels of plasma DNA are a strong risk factor for lung cancer.

OBJECTIVES

To assess the diagnostic performance and prognostic value of plasma DNA levels in a cohort of 1,035 heavy smokers monitored by annual spiral computed tomography (CT) for 5 years.

METHODS

Plasma DNA levels were determined through real-time quantitative PCR at baseline and at time of lung cancer diagnosis. Screening performance of the assay was calculated through the area under the receiver-operating characteristic curve (AUC-ROC). Kaplan-Meier analyses were computed for association with prognosis.

MEASUREMENTS AND MAIN RESULTS

Median baseline concentration of plasma DNA was not different in individuals who developed CT-detected lung cancers in the 5-year period (n = 38) versus cancer-free control subjects (AUC-ROC, 0.496; P = 0.9330), and only slightly higher at the time of cancer diagnosis (AUC-ROC, 0.607; P = 0.0369). At surgery, plasma DNA was higher in tumors detected at baseline (AUC-ROC, 0.80; P < 0.0001) and in Stage II to IV tumors detected during the first 2 years of screening (AUC-ROC, 0.87; P < 0.0001). A longitudinal study of plasma DNA levels showed increased values approaching to lung cancer diagnosis (P = 0.0010). Higher plasma DNA was significantly associated with poorer 5-year survival (P = 0.0066).

CONCLUSIONS

Baseline assessment of plasma DNA level does not improve the accuracy of lung cancer screening by spiral CT in heavy smokers. Higher levels of plasma DNA at surgery might represent a risk factor for aggressive disease.

5,5'-Dibromo-bis(3'-indolyl)methane induces Kruppel-like factor 4 and p21 in colon cancer cells

Bis(3'-indolyl)methane (DIM) is a metabolite of the phytochemical indole-3-carbinol, and both compounds exhibit a broad spectrum of anticancer activities. We have developed a series of synthetic symmetrical ring-substituted DIM analogues, including 5,5'-dibromoDIM, which are more potent than DIM as inhibitors of cancer cell and tumor growth. In colon cancer cells, 5,5'-dibromoDIM decreased cell proliferation and inhibited G(0)-G(1)- to S-phase progression, and this was accompanied by induction of the cyclin-dependent kinase inhibitor p21 in HT-29 and RKO colon cancer cells. Mechanistic studies showed that induction of p21 in both RKO (p53 wild-type) and HT-29 (p53 mutant) cells by 5,5'-dibromoDIM was Krüppel-like factor 4 (KLF4) dependent, and induction of p53 in RKO cells was also KLF4 dependent. Analysis of the p21 promoter in p53-dependent RKO cells showed that 5,5'-dibromoDIM activated p21 gene expression through the proximal GC-rich sites 1 and 2, and chromatin immunoprecipitation assays showed that KLF4 and p53 bound to this region of the promoter, whereas in HT-29 cells unidentified upstream cis-elements were required for induction of p21. 5,5'-DibromoDIM (30 mg/kg/d) also inhibited tumor growth and induced p21 in athymic nude mice bearing RKO cells as xenografts, showing that ring-substituted DIM such as 5,5'-dibromoDIM represent a novel class of mechanism-based drugs for clinical treatment of colon cancer.

Roles of Krüpel-like factor 4 in normal homeostasis, cancer and stem cells

Krüpel-like factor 4 (KLF4) is a zinc finger-type transcription factor expressed in a variety of tissues, including the epithelium of the intestine and the skin, and it plays an important role in differentiation and cell cycle arrest. Depending on the gene targeted, KLF4 can both activate and repress transcription. Moreover, in certain cellular contexts, KLF4 can function as a tumor suppressor or an oncogene. Finally, KLF4 is important in reprogramming differentiated fibroblasts into inducible pluripotent stem cells, which highly resemble embryonic stem cells. This review summarizes what is known about the diverse functions of KLF4 as well as their molecular mechanisms.

Universal Reference RNA is not a representative normal sample for oligonucleotide microarray studies

Translational research has been defined as the scientific study using human material that will ultimately generate patient specific data. A major caveat in human directed study is the availability of high quality and quantities of patient derived homogeneous cells for analysis. Whereas there exist sources for which tumor tissue and blood samples can be made available, the same cannot be said for normal tissue. The absence of normal control tissue has led to the creation of pooled cell lines and tissues for purchase known as "reference RNA". Although initially created for purposes of standardization, the difficulty associated with acquiring normal tissue has led some investigators to use sources of universal pooled RNA for comparative analysis with clinical tissue specimens. In order to study the effects of using Universal Reference RNA on expression profiling experiments we have evaluated the performance of universal RNA compared to RNA obtained from a purified population of colon epithelial cells in defining a set of altered transcripts in colon cancer.

Pathologic and molecular features of screening low-dose computed tomography (LDCT)-detected lung cancer: a baseline and 2-year repeat study

Detailed studies on the pathologic and molecular features of low-dose computed tomography (LDCT)-detected carcinomas and comparison with unscreened tumors are still lacking. We evaluated the histopathologic features of 89 LDCT-detected lung cancers resected between 2004 and 2006. These tumors occurred within a cohort of 5202 volunteers undergoing annual LDCT, aged > or =50 years, and with a minimum 20 pack-year index. In adenocarcinomas, central scar diameter, invasion foci size and K-ras mutations were also assessed. The results were compared with those of 89 consecutive lung carcinomas matched for confounding factors (sex, smoking habit), selected from group of 363 consecutive clinically worked-up lung cancer, surgically resected in the same period and at the same Institution. The tumors were diagnosed in 63 males and 26 females (range 50-79 years), 55 of which diagnosed at the baseline (1.05%) and 34 (including 10 repeat cancers) operated after work-up during the second year (0.72%). LDCT-detected tumors showed high resectability rate (89%), earlier stage (63%) and prevalence of adenocarcinoma nodules (72%), most often of the mixed subtype, in comparison with unscreened tumors. A similar prevalence of K-ras mutations was found in both screened and unscreened adenocarcinomas. Repeat cancers were found in 10 screened patients, and were predominantly stage I adenocarcinomas of mixed subtype exhibiting smaller dimension but greater central scar diameter and stromal invasion size in comparison with the other second-year, slower-growing adenocarcinomas. Multiple tumor nodules were identified in 10 patients exclusively at the baseline, were mostly mixed adenocarcinomas and differed in their K-ras mutation profile. Screening-detected lung cancers shared most of the histologic features of fully malignant tumors, in addition to a similar prevalence of K-ras mutations, despite their earlier detection and less advanced clinical stage. Repeat cancers are potentially aggressive tumors. K-ras mutation analysis supports the impression that multifocal tumors at baseline are separate synchronous primaries.

Kruppel-like factor 4 is a novel mediator of selenium in growth inhibition

A previous prevention trial showed that selenium supplementation was effective in reducing (by 50%) the incidence of prostate cancer. Selenium has been reported to inhibit the growth of prostate cancer cells in vitro. Multiple mechanisms are likely to be operative in the underlying effect of selenium. Here, we report that Krüppel-like factor 4 (KLF4), a transcription factor of the KLF family, is an important target of selenium. We found that selenium up-regulates KLF4 expression and increases the DNA-binding activity of KLF4 in both the androgen-dependent LNCaP and the androgen-independent PC-3 human prostate cancer cells. The increase of KLF4 mRNA is accounted for primarily by enhanced transcription, although the contribution of a slight abatement in mRNA degradation cannot be ruled out. KLF4 knockdown using short interference RNA significantly weakens the effects of selenium on DNA synthesis inhibition, apoptosis induction, and the expression of three KLF4 target genes, cyclin D1, p21/WAF1, and p27/Kip1. In addition, the overexpression of KLF4 not only leads to an induction of apoptosis in the control cells, but also enhances the DNA synthesis-suppressive and-proapoptotic activities of selenium. Taken together, our results suggest that KLF4 plays a key role in mediating the growth-inhibitory effect of selenium in prostate cancer cells.

Matrix GLA protein, an inhibitory morphogen in pulmonary vascular development

Deficiency of matrix GLA protein (MGP), an inhibitor of bone morphogenetic protein (BMP)-2/4, is known to cause arterial calcification and peripheral pulmonary artery stenosis. Yet the vascular role of MGP remains poorly understood. To further investigate MGP, we created a new MGP transgenic mouse model with high expression of the transgene in the lungs. The excess MGP led to a disruption of the pulmonary pattern of BMP-4, and resulted in significant morphological defects in the pulmonary artery tree. Specifically, the vascular branching pattern lacked characteristic side branching, whereas control lungs had extensive side branching accounting for as much as 40% of the vascular endothelium. The vascular changes could be explained by a dramatic reduction of phosphorylated SMAD1/5/8 in the alveolar epithelium, and in epithelial expression of the activin-like kinase receptor 1 and vascular endothelial growth factor, both critical in vascular formation. Abnormalities were also found in the terminal airways and in lung cell differentiation; high levels of surfactant protein-B were distributed in an abnormal pattern suggesting lost coordination between vasculature and airways. Ex vivo, lung cells from MGP transgenic mice showed higher proliferation, in particular surfactant protein B-expressing cells, and conditioned medium from these cells poorly supported in vitro angiogenesis compared with normal lung cells. The vascular branching defect can be mechanistically explained by a computational model based on activator/inhibitor reaction-diffusion dynamics, where BMP-4 and MGP are considered as an activating and inhibitory morphogen, respectively, suggesting that morphogen interactions are important for vascular branching.

The convergent development of molecular-targeted drugs for cancer treatment and prevention

Advances in our understanding of multistep and field carcinogenesis are erasing the clear demarcation of intraepithelial neoplasia from invasive neoplasia. The growing ability to define a very high risk of cancer is forging important commonalities between prevention and therapy, such as in potential prognostic/predictive markers, agents, and side effects that patients would be willing to tolerate, and the logistics of definitive trials. The emergence of promising new molecular-targeted agents and new technologies for screening and early detection provides new opportunities for applying clinical trial designs that integrate therapy and prevention end points. Such trials may be used to facilitate targeted drug development and help identify strategies for both cancer prevention and advanced cancer therapy. These several advances are creating a convergence of cancer therapy with cancer prevention that promises to streamline the development of targeted drugs and improve the control of major cancers.

Lung cancer screening

The result of a lung cancer screening program should be fewer lung cancer-specific deaths in the screened population. Studies evaluating chest imaging as a screening tool for lung cancer have not shown a reduction in lung cancer-specific mortality to date. The ability of institutions using chest imaging to meet the criteria for successful screening programs has also been debated. Contentious issues include the presence of an overdiagnosis bias, the ability to find preclinical disease at a curable point in time, the amount of pseudodisease identified, and the cost-effectiveness of screening programs. Current guidelines remain vague as randomized trials are being completed and technologic advances are occurring. The ultimate face of a successful lung cancer screening program is yet to be defined.

Metastatic progression and gene expression between breast cancer cell lines from African American and Caucasian women

African American (AA) women have a lower overall incidence of breast cancer than do Caucasian (CAU) women, but a higher overall mortality. Little is known as to why the incidence of breast cancer is lower yet mortality is higher in AA women. Many studies speculate that this is only a socio-economical problem. This investigation suggests the possibility that molecular mechanisms contribute to the increased mortality of AA women with breast cancer. This study investigates the expression of 14 genes which have been shown to play a role in cancer metastasis. Cell lines derived from AA and CAU patients were analyzed to demonstrate alterations in the transcription of genes known to be involved in cancer and the metastatic process. Total RNA was isolated from cell lines and analyzed by RT-PCR analysis. Differential expression of the 14 targeted genes between a spectrum model (6 breast cancer cell lines and 2 non-cancer breast cell lines) and a metastasis model (12 metastatic breast cancer cell lines) were demonstrated. Additionally, an in vitro comparison of the expression established differences in 5 of the 14 biomarker genes between African American and Caucasian breast cell lines. Results from this study indicates that altered expression of the genes Atp1b1, CARD 10, KLF4, Spint2, and Acly may play a role in the aggressive phenotype seen in breast cancer in African American women.

Loss of Krüppel-like factor 4 expression contributes to Sp1 overexpression and human gastric cancer development and progression

PURPOSE

Increasing evidence indicates that the transcription factor, Sp1, regulates the expression of multiple genes involved in tumor development and progression. We have recently reported that Sp1 overexpression is directly correlated with the angiogenic potential of and poor prognosis for human gastric cancer. However, the underlying mechanisms that result in Sp1 overexpression remain unclear.

EXPERIMENTAL DESIGN

The expression of Sp1 and Krüppel-like factor 4 (KLF4), a potential tumor suppressor gene, in gastric cancer tissue was analyzed by immunohistochemistry and Western blot analysis. Alterations of Sp1 and KLF4 expression were achieved by gene transfer and verified by Northern and Western blot analyses. Furthermore, Sp1 promoter activity assay, electrophoretic mobility shift assay, and chromatin immunoprecipitation assay were done to identify the KLF4 binding sites on the Sp1 promoter.

RESULTS

Mutually exclusive expression of Sp1 and KLF4 was evident in gastric cancer and noncancerous tissue. Specifically, strong Sp1 expression but loss of KLF4 expression was found in cancer tissue, whereas the adjacent noncancerous tissue showed negative Sp1 expression but strong KLF4 expression. Enforced KLF4 expression repressed Sp1 expression at the promoter activity, mRNA, and protein levels. Moreover, a region within the proximal Sp1 promoter was identified to have overlapping KLF4- and Sp1-binding sites, to which KLF4 and Sp1 compete for binding. Sp1 positively regulated its own promoter, whereas KLF4 did the opposite.

CONCLUSIONS

Our data suggests that disruption of KLF4-mediated negative regulation contributes to the molecular events of Sp1 overexpression and to the development and progression of human gastric cancer.

Regulation of bone morphogenetic protein-4 by matrix GLA protein in vascular endothelial cells involves activin-like kinase receptor 1

Matrix GLA protein (MGP) has previously been shown to enhance expression of vascular endothelial growth factor (VEGF) through the activin-like kinase receptor 1 (ALK1) in bovine aortic endothelial cells. MGP has also been identified as an inhibitor of bone morphogenetic protein-2 (BMP-2). This study showed that the effect of MGP on ALK1 signaling and VEGF expression in bovine aortic endothelial cells was dose-dependent, that a progressive increase of MGP levels ceased to be stimulatory and instead turned inhibitory. We identified a new regulatory pathway involving BMP that may explain this response. BMP-2 and BMP-4 induced expression of ALK1 in a dose-dependent fashion as determined by real-time PCR and immunoblotting. Activation of ALK1 signaling induced expression of MGP in addition to that of VEGF, allowing for negative feedback regulation of BMP by MGP. MGP inhibited BMP-4 activity similarly to that of BMP-2 and interacted with BMP-4 on a protein level as determined by co-immunoprecipitation. The dose-dependent effect on ALK1 expression and the stimulation of MGP and VEGF expression were dependent on signaling by transforming growth factor-beta (TGF-beta) and ALK1. Inhibition of TGF-beta by neutralizing antibodies abolished the inhibitory effect of high BMP-4 levels on ALK1 expression and the induction of MGP and VEGF. Depletion of ALK1 by small interfering RNA abolished the induction of MGP and VEGF. MGP promoter activity was also stimulated by BMP-4 in a TGF-beta-dependent fashion. The results suggest that the effects of BMP on endothelial cells occur in part through induction of ALK1, an effect that may be limited by ALK1-induced MGP.

Lung Cancer Screening

Advances in imaging technology have ushered in a new era for lung cancer screening in high-risk individuals using computed tomographic (CT) scans. Although most published studies are nonrandomized observational cohorts of volunteers, the ability of CT scans to detect early stage lung cancer is undisputable. What is unresolved is the ability of spiral CT screening to affect lung cancer-related mortality. A large randomized trial sponsored by the National Cancer Institute to address this question is currently under way. Genomic and proteomic approaches promise to complement the ability of spiral CT to detect early lung cancer in the next few years. Currently, the decision to screen for lung cancer should involve a careful discussion with the individuals involved about the potential advantages, costs, and drawbacks of the approach.