Overexpression of candidate tumor suppressor gene FUS1 isolated from the 3p21.3 homozygous deletion region leads to G1 arrest and growth inhibition of lung cancer cells

Advancements in Gene Therapy for Non-Small Cell Lung Cancer: Current Approaches and Future Prospects

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide, characterized by late diagnosis and resistance to conventional therapies. Gene therapy has emerged as a promising alternative for NSCLC therapy, especially for patients with advanced disease who have exhausted conventional treatments. This article delved into the current developments in gene therapy for NSCLC, including gene replacement and tumor suppressor gene therapy, gene silencing, CRISPR/Cas9 gene editing, and immune modulation with CAR-T cell therapy. In addition, the challenges and future prospects of gene-based therapies for NSCLC were discussed.

Circ_RUSC2 Sequesters miR-661 and Elevates TUSC2 Expression to Suppress Colorectal Cancer Progression

BACKGROUND

Despite advancements in diagnostic efficiency, colorectal cancer (CRC) remains a leading cause of cancer-related mortality, with increasing incidence rates. Circular RNA (circRNA) is a closed-loop, generally stable noncoding RNA that functions as a sponge for microRNAs in CRC. The purpose of this study was to investigate the function and underlying mechanism of circ_RUSC2, a new circRNA, in CRC. The expression levels of circ_RUSC2, miR-661, and TUSC2 were assessed using qRT-PCR, Western blot, and immunohistochemistry. Functional assays, including CCK-8, Transwell, and scratch wound healing, were performed to evaluate cell proliferation, migration, and invasion. RNA pull-down and actinomycin D assays were used to study RNA interactions and stability. In both CRC cells and tissues, miR-661 was markedly elevated, while circ_RUSC2 expression was considerably reduced. Poor differentiation, distant metastases, lymph node metastases, and an advanced stage were all strongly correlated with either miR-661 overexpression or circ_RUSC2 downregulation. circ_RUSC2 was more stable compared to its linear RUSC2 mRNA. CRC cell invasion, migration, and proliferation were suppressed by circ_RUSC2 ectopic expression; this inhibitory effect was restored by a miR-661 mimic. Circ_RUSC2 served as miR-661's sponge. TUSC2 counteracted the effects of miR-661, which stimulated CRC cell proliferation, migration, and invasion. At the post-transcriptional level, miR-661 controlled the expression of TUSC2 in CRC cells. In comparison to the negative control, circ_RUSC2 expression was markedly reduced, and its half-life was shortened by methyltransferase-like 3 (METTL3) knockdown. Circ_RUSC2 is a stable cytoplasmic circRNA. Circ_RUSC2 inhibits CRC cell malignant phenotypes via the miR-661/TUSC2 axis. The onset and progression of CRC are linked to the downregulation of Circ_RUSC2. circ_RUSC2 might become more stable through N6-methyladenosine (m6A) methylation regulated by METTL3. According to our research, circ_RUSC2 might be a new biomarker and treatment target for CRC.

NPRL2 gene therapy induces effective antitumor immunity in KRAS/STK11 mutant anti-PD1 resistant metastatic non-small cell lung cancer (NSCLC) in a humanized mouse model

Expression of NPRL2/TUSC4, a tumor-suppressor gene, is reduced in many cancers including NSCLC. Restoration of NPRL2 induces DNA damage, apoptosis, and cell-cycle arrest. We investigated NPRL2 antitumor immune responses in aPD1R/KRAS/STK11mt NSCLC in humanized-mice. Humanized-mice were generated by transplanting fresh human cord blood-derived CD34 stem cells into sub-lethally irradiated NSG mice. Lung-metastases were developed from KRAS/STK11mt/aPD1R A549 cells and treated with NPRL2 w/wo pembrolizumab. NPRL2-treatment reduced lung metastases significantly, whereas pembrolizumab was ineffective. Antitumor effect was greater in humanized than non-humanized-mice. NPRL2 + pembrolizumab was not synergistic in KRAS/STK11mt/aPD1R tumors but was synergistic in KRASwt/aPD1S H1299. NPRL2 also showed a significant antitumor effect on KRASmt/aPD1R LLC2 syngeneic-tumors. The antitumor effect was correlated with increased infiltration of human cytotoxic-T, HLA-DR+DC, CD11c+DC, and downregulation of myeloid and regulatory-T cells in TME. Antitumor effect was abolished upon in-vivo depletion of CD8-T, macrophages, and CD4-T cells whereas remained unaffected upon NK-cell depletion. A distinctive protein-expression profile was found after NPRL2 treatment. IFNγ, CD8b, and TBX21 associated with T-cell functions were significantly increased, whereas FOXP3, TGFB1/B2, and IL-10RA were strongly inhibited by NPRL2. A list of T-cell co-inhibitory molecules was also downregulated. Restoration of NPRL2 exhibited significantly slower tumor growth in humanized-mice, which was associated with increased presence of human cytotoxic-T, and DC and decreased percentage of Treg, MDSC, and TAM in TME. NPRL2-stable cells showed a substantial increase in colony-formation inhibition and heightened sensitivity to carboplatin. Stable-expression of NPRL2 resulted in the downregulation of MAPK and AKT-mTOR signaling. Taken-together, NPRL2 gene-therapy induces antitumor activity on KRAS/STK11mt/aPD1R tumors through DC-mediated antigen-presentation and cytotoxic immune-cell activation.

Immunohistochemical and molecular evaluation of TUSC2 expression in breast cancer

OBJECTIVE

Tumor suppressor candidate 2 has shown to be deleted in lung, colon, and bladder cancer types. In the present study, we aimed to investigate the expression of TUSC2 in breast cancer.

MATERIALS AND METHODS

A total of thirty patients with breast cancer were included in the study. Normal and tumor tissue samples from fresh mastectomy materials were stored at -80 C until the number of cases was completed for gene expression analysis. Histopathological examination was carried out with routine hematoxylin & eosin method. TUSC2 staining was performed for immunohistochemical analysis.

RESULTS

The tumors of thirteen patients were Luminal A, fourteen patients were Luminal B, one patient was cerbB2(+), and tumors of two patients were triple-negative. Ki67 proliferation index was less than 14% in fifteen cases and tumor size was less than 2 cm in seven cases. Lymphovascular invasion and lymph node metastasis were present in thirteen cases. Statistically, TUSC2 expression significantly decreased or was lost in breast tumor tissues compared to normal tissues (p < 0.0001). TUSC2 expression decreased as the Ki67 proliferation index increased (p = 0.0003), and TUSC2 expression decreased as tumor size increased (p = 0.0483). The loss or decrease in the TUSC2 expression was significant as the tumor grade increased (p = 0.3740). Gene expression analysis correlated with immunohistochemistry results.

CONCLUSION

The results of the present study demonstrated a decrease or loss of TUSC2 expression in breast cancer tissue compared to normal tissue. A correlation was found between TUSC2 expression and Ki67 proliferation index and tumor size.

Mitochondrial Fus1/Tusc2 and cellular Ca2+ homeostasis: tumor suppressor, anti-inflammatory and anti-aging implications

FUS1/TUSC2 (FUSion1/TUmor Suppressor Candidate 2) is a tumor suppressor gene (TSG) originally described as a member of the TSG cluster from human 3p21.3 chromosomal region frequently deleted in lung cancer. Its role as a TSG in lung, breast, bone, and other cancers was demonstrated by several groups, but molecular mechanisms of its activities are starting to unveil lately. They suggest that Fus1-dependent mechanisms are relevant in etiologies of diseases beyond cancer, such as chronic inflammation, bacterial and viral infections, premature aging, and geriatric diseases. Here, we revisit the discovery of FUS1 gene in the context of tumor initiation and progression, and review 20 years of research into FUS1 functions and its molecular, structural, and biological aspects that have led to its use in clinical trials and gene therapy. We present a data-driven view on how interactions of Fus1 with the mitochondrial Ca2+ (mitoCa2+) transport machinery maintain cellular Ca2+ homeostasis and control cell apoptosis and senescence. This Fus1-mediated cellular homeostasis is at the crux of tumor suppressor, anti-inflammatory and anti-aging activities.

NEDD4 degrades TUSC2 to promote glioblastoma progression

Whether tumor suppressor candidate 2 (TUSC2) plays an important role in glioblastoma (GBM) progression is largely unknown. Whether TUSC2 undergoes polyubiquitination is unknown. Herein, we report that TUSC2 protein expression is reduced/lost in GBM compared to normal brain due to protein destabilization; TUSC2 mRNA is equally expressed in both tissues. NEDD4 E3 ubiquitin ligase polyubiquitinates TUSC2 at residue K71, and the TUSC2-K71R mutant is resistant to NEDD4-mediated proteasomal degradation. Analysis of GBM specimens showed NEDD4 protein is highly expressed in GBM and the level is inversely correlated with TUSC2 protein levels. Furthermore, TUSC2 restoration induces apoptosis and inhibits patient-derived glioma stem cells (PD-GSCs) in vitro and in vivo. Conversely, TUSC2-knockout promotes PD-GSCs in vitro and in vivo. RNA-Seq analysis and subsequent validations showed GBM cells with TUSC2-knockout expressed increased Bcl-xL and were more resistant to apoptosis induced by a Bcl-xL-specific BH3 mimetic. A TUSC2-knockout gene signature created from the RNA-seq data predicts poor patient survival. Together, these findings establish that NEDD4-mediated polyubiquitination is a novel mechanism for TUSC2 degradation in GBM and that TUSC2 loss promotes GBM progression in part through Bcl-xL upregulation.

Mitochondrial Tumor Suppressors-The Energetic Enemies of Tumor Progression

Tumor suppressors represent a critical line of defense against tumorigenesis. Their mechanisms of action and the pathways they are involved in provide important insights into cancer progression, vulnerabilities, and treatment options. Although nuclear and cytosolic tumor suppressors have been extensively investigated, relatively little is known about tumor suppressors localized within the mitochondria. However, recent research has begun to uncover the roles of these important proteins in suppressing tumorigenesis. Here, we review this newly developing field and summarize available information on mitochondrial tumor suppressors.

Delivery of novel coumarin-dihydropyrimidinone conjugates through mixed polymeric nanoparticles to potentiate therapeutic efficacy against triple-negative breast cancer

To date, most of the accessible therapeutic options are virtually non-responsive towards triple-negative breast cancer (TNBC) due to its highly aggressive and metastatic nature. Interestingly, chemotherapy reacts soundly in many TNBC cases compared to other types of breast cancer. However, the side effects of many chemotherapeutic agents are still under cross-examination, and thus prohibit their extensive uses. In this present study, we have developed a series of coumarin-dihydropyrimidinone conjugates (CDHPs) and subsequently their poly(lactic-co-glycolic acid) (PLGA)-PEG₄₀₀₀ mixed copolymer nanoparticles as excellent chemotherapeutic nanomedicine to control TNBC. Among all the synthesized CDHPs, CDHP-4 (prepared by the combination of EDCO with 3,4-difluorobenzaldehyde) showed excellent therapeutic effect on a wide variety of cancer cell lines, including TNBC. Besides, it can control the metastasis and stemness property of TNBC. Furthermore, the nano-encapsulation of CDHP-4 in a mixed polymer nanoparticle system (CDHP-4@PP-NPs) and simultaneous delivery showed much improved therapeutic efficacy at a much lower dose, and almost negligible side effects in normal healthy cells or organs. The effectiveness of the present therapeutic agent was observed both in intravenous and oral mode of administration in in vivo experiments. Moreover, on elucidating the molecular mechanism, we found that CDHP-4@PP-NPs could exhibit apoptotic, anti-migratory, as well as anti-stemness activity against TNBC cell lines through the downregulation of miR-138. We validated our findings in MDA-MB-231 xenograft chick embryos, as well as in 4T1-induced mammary tumor-bearing BALB/c mice models, and studied the bio-distribution of CDHP-4@PP-NPs on the basis of the photoluminescence property of nanoparticles. Our recent study, hence for the first time, unravels the synthesis of CDHP-4@PP-NPs and the molecular mechanism behind the anti-migration, anti-stemness and anti-tumor efficacy of the nanoparticles against the TNBC cells through the miR-138/p65/TUSC2 axis.

Malathion induced cancer-linked gene expression in human lymphocytes

BACKGROUND

Malathion is the most widely used organophosphate pesticide in agriculture. Increasing cancer incidence in agricultural workers and their children links to the exposure of malathion. Identification of genes involved in the process of carcinogenesis is essential for exploring the role of malathion. The alteration in gene expression by malathion in human lymphocytes has not been explored yet, although hematological malignancies are rampant in humans.

OBJECTIVE

This study investigates the malathion induced expression of cancer associated genes in human lymphocytes.

METHODS

Human lymphocyte viability and colony-forming ability were analyzed in malathion treated and control groups. Gene expression profile in control and malathion treated human lymphocytes were performed using a microarray platform. The genes which have significant functions and those involved in different pathways were analyzed using the DAVID database. Differential gene expression upon malathion exposure was validated by quantitative real-time (qRT)-PCR.

RESULTS

Malathion caused a concentration-dependent reduction in human lymphocyte viability. At low concentration (50 μg/mL) of malathion treatment, human lymphocytes were viable indicating that low concentration of malathion is not cytotoxic and induces the colony formation. Total of 659 genes (15%) were up regulated and 3729 genes (85%) were down regulated in malathion treated human lymphocytes. About 57 cancer associated genes related to the growth and differentiation of B and T cells, immunoglobulin production, haematopoiesis, tumor suppression, oncogenes and signal transduction pathways like MAPK and RAS were induced by malathion.

CONCLUSION

This study evidences the carcinogenic nature of malathion. Low concentration of this pesticide is not cytotoxic and induces differentially regulated genes in human lymphocytes, which are involved in the initiation, progression, and pathogenesis of cancer.

The TUSC2 Tumour Suppressor Inhibits the Malignant Phenotype of Human Thyroid Cancer Cells via SMAC/DIABLO Protein

Thyroid carcinoma is the most common endocrine cancer and includes different forms. Among these, anaplastic thyroid carcinoma (ATC) is the rarest but the most lethal subtype, compared to papillary thyroid carcinoma (PTC) which shows an overall good prognosis. We have previously showed that Tumor Suppressor Candidate 2 (TUSC2), a known tumour suppressor gene, is downregulated in human PTC and ATC compared to normal thyroid samples. The aim of this study was to gain insight into the molecular mechanisms induced by TUSC2 in thyroid cancer cells. Here, we stably transfected TUSC2 in papillary (TPC-1) and in anaplastic (8505C) thyroid cancer cell lines and studied its effects on several biological processes, demonstrating that TUSC2 overexpression decreased thyroid cancer cell proliferation, migration and invasion. Through the proteome profiler apoptosis array, we observed that TUSC2 increased sensitivity to apoptosis by increasing the SMAC/DIABLO and CYTOCHROME C proteins. On the other hand, transient silencing of TUSC2, by siRNA, in an immortalized thyroid follicular epithelial cell line (Nthy-ori 3-1) showed the opposite effect. Finally modulation of SMAC/DIABLO partially rescued the biological effects of TUSC2. Thus, our data highlight a tumour suppressor role of TUSC2 in thyroid carcinogenesis, suggesting that it could be a promising target and biomarker for thyroid carcinoma.

MicroRNA-663 facilitates the growth, migration and invasion of ovarian cancer cell by inhibiting TUSC2

Background

MicroRNAs (miRNAs) have emerged as the critical modulators of the tumorigenesis and tumor progression.

Methods

The levels of miR-663 in ovarian cancer cell lines and clinical tissues were detected using qRT-PCR assays. The Transwell invasion and wound healing assay were conducted to assess the roles of miR-663 in the migration and invasion of ovarian cancer cell in vitro. Rescue assays were carried out to confirm the contribution of tumor suppressor candidate 2 (TUSC2) in the aggressiveness of cancer cell which was regulated by miR-663.

Results

The levels of miR-663 were up-regulated in ovarian cancer tissues in comparison with the corresponding normal tissues. Up-regulation of miR-663 increased the proliferation, colony formation, migration and invasion of ovarian cancer SKOV3 cell. Additional, over-expression of miR-663 increased the tumor growth of SKOV3 in xenograft model. Bioinformatics analysis and luciferase reporter assay identified that miR-663 decreased the level of TUSC2 via binding to the 3′-UTR of TUSC2 gene. Finally, the expression of TUSC2 was inversely associated with the level of miR-663 in ovarian carcinoma tissue and over-expression of TUSC2 inhibited the migration and invasion abilities of SKOV3 that was promoted by miR-663.

Conclusion

Altogether, these results indicate that miR-663 acts as a potential tumor-promoting miRNA through targeting TUSC2 in ovarian cancer.

Electronic supplementary material

The online version of this article (10.1186/s40659-019-0219-6) contains supplementary material, which is available to authorized users.

Gene Therapy for Lung Cancer

Gene therapy was originally conceived to treat monogenic diseases. The replacement of a defective gene with a functional gene can theoretically cure the disease. In cancer, multiple genetic defects are present and the molecular profile changes during the course of the disease, making the replacement of all defective genes impossible. To overcome these difficulties, various gene therapy strategies have been adopted, including immune stimulation, transfer of suicide genes, inhibition of driver oncogenes, replacement of tumor-suppressor genes that could mediate apoptosis or anti-angiogenesis, and transfer of genes that enhance conventional treatments such as radiotherapy and chemotherapy. Some of these strategies have been tested successfully in non-small-cell lung cancer patients and the results of laboratory studies and clinical trials are reviewed herein.

Mitochondria, calcium, and tumor suppressor Fus1: At the crossroad of cancer, inflammation, and autoimmunity

Mitochondria present a unique set of key intracellular functions such as ATP synthesis, production of reactive oxygen species (ROS) and Ca²⁺ buffering. Mitochondria both encode and decode Ca²⁺ signals and these interrelated functions have a direct impact on cell signaling and metabolism.

High proliferative potential is a key energy-demanding feature shared by cancer cells and activated T lymphocytes. Switch of a metabolic state mediated by alterations in mitochondrial homeostasis plays a fundamental role in maintenance of the proliferative state. Recent studies show that tumor suppressors have the ability to affect mitochondrial homeostasis controlling both cancer and autoimmunity. Herein, we discuss established and putative mechanisms of calcium–dependent regulation of both T cell and tumor cell activities. We use the mitochondrial protein Fus1 as a case of tumor suppressor that controls immune response and tumor growth via maintenance of mitochondrial homeostasis. We focus on the regulation of mitochondrial Ca²⁺ handling as a key function of Fus1 and highlight the mechanisms of a crosstalk between Ca²⁺ accumulation and mitochondrial homeostasis. Given the important role of Ca²⁺ signaling, mitochondrial Ca²⁺ transport and ROS production in the activation of NFAT and NF-κB transcription factors, we outline the importance of Fus1 activities in this context.

The pseudogene TUSC2P promotes TUSC2 function by binding multiple microRNAs

Various non-coding regions of the genome, once presumed to be ‘junk’ DNA, have recently been found to be transcriptionally active. In particular, pseudogenes are now known to have important biological roles. Here we report that transcripts of the two tumour suppressor candidate-2 pseudogenes (TUSC2P), found on chromosomes X and Y, are homologous to the 3′-UTR of their corresponding protein coding transcript, TUSC2. TUSC2P and the TUSC2 3′-UTR share many common miRNA-binding sites, including miR-17, miR-93, miR-299-3p, miR-520a, miR-608 and miR-661. We find that ectopic expression of TUSC2P and the TUSC2 3′-UTR inhibits cell proliferation, survival, migration, invasion and colony formation, and increases tumour cell death. By interacting with endogenous miRNAs, TUSC2P and TUSC2 3′-UTR arrest the functions of these miRNAs, resulting in increased translation of TUSC2. The TUSC2P and TUSC2 3′-UTR could thus be used as combinatorial miRNA inhibitors and might have clinical applications.

Non-coding RNAs have recently emerged as crucial regulators of gene expression. Here Rutnam et al. identify a pseudogene complementary to the 3′-UTR of the TUSC2 tumour suppressor that regulates TUSC2 levels by acting as a decoy for endogenous microRNAs and thereby inhibits tumorigenesis.

Exogenous Restoration of TUSC2 Expression Induces Responsiveness to Erlotinib in Wildtype Epidermal Growth Factor Receptor (EGFR) Lung Cancer Cells through Context Specific Pathways Resulting in Enhanced Therapeutic Efficacy

Expression of the tumor suppressor gene TUSC2 is reduced or absent in most lung cancers and is associated with worse overall survival. In this study, we restored TUSC2 gene expression in several wild type EGFR non-small cell lung cancer (NSCLC) cell lines resistant to the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor erlotinib and analyzed their sensitivity to erlotinib in vitro and in vivo. A significant inhibition of cell growth and colony formation was observed with TUSC2 transient and stable expression. TUSC2-erlotinib cooperativity in vitro could be reproduced in vivo in subcutaneous tumor growth and lung metastasis formation lung cancer xenograft mouse models. Combination treatment with intravenous TUSC2 nanovesicles and erlotinib synergistically inhibited tumor growth and metastasis, and increased apoptotic activity. High-throughput qRT-PCR array analysis enabling multi-parallel expression profile analysis of eighty six receptor and non-receptor tyrosine kinase genes revealed a significant decrease of FGFR2 expression level, suggesting a potential role of FGFR2 in TUSC2-enhanced sensitivity to erlotinib. Western blots showed inhibition of FGFR2 by TUSC2 transient transfection, and marked increase of PARP, an apoptotic marker, cleavage level after TUSC2-erlotinb combined treatment. Suppression of FGFR2 by AZD4547 or gene knockdown enhanced sensitivity to erlotinib in some but not all tested cell lines. TUSC2 inhibits mTOR activation and the latter cell lines were responsive to the mTOR inhibitor rapamycin combined with erlotinib. These results suggest that TUSC2 restoration in wild type EGFR NSCLC may overcome erlotinib resistance, and identify FGFR2 and mTOR as critical regulators of this activity in varying cellular contexts. The therapeutic activity of TUSC2 could extend the use of erlotinib to lung cancer patients with wildtype EGFR.

Identification of guanine nucleotide-binding protein γ-7 as an epigenetically silenced gene in head and neck cancer by gene expression profiling

Silencing of tumor suppressor genes plays a vital role in head and neck carcinogenesis. Aberrant hypermethylation in the promoter region of some known or putative tumor suppressor genes occurs frequently during the development of various types of cancer including head and neck squamous cell carcinoma (HNSCC). In this study we used an expanded mRNA expression profiling approach followed by microarray expression analysis to identify epigenetically inactivated genes in HNSCC. Two HNSCC cell lines were treated with 5-aza-2'-deoxycytidine followed by microarray analysis to identify epigenetically silenced genes in HNSCC. We found 1,960, 614 and 427 genes were upregulated in the HNSCC cell lines JHU-012, JHU-011 and the combination of both cell lines, respectively. HNSCC tumor and normal mucosal samples were used for gene profiling by a 47K mRNA gene expression array and we found 7,140 genes were downregulated in HNSCC tumors compared to normal mucosa, as determined by microarray analysis, and were integrated with cell line data. Integrative analysis defined 126 candidate genes, of which only seven genes showed differential methylation in tumors and no methylation in normal mucosa after bisulfite sequencing. Following validation by QMSP, one gene, guanine nucleotide-binding protein γ-7 (GNG7), was confirmed to be highly methylated in tumors and unmethylated in normal mucosal and salivary rinse samples demonstrating cancer-specific methylation in HNSCC tissues. TXNIP and TUSC2 were partially methylated in tumors and normal salivary rinses but unmethylated in normal mucosa. We concluded that GNG7 is a highly specific promoter methylated gene associated with HNSCC. In addition, TXNIP and TUSC2 are also potential biomarkers for HNSCC.

Targeting glioma stem cells by functional inhibition of a prosurvival oncomiR-138 in malignant gliomas

Malignant gliomas are the most aggressive forms of brain tumors, associated with high rates of morbidity and mortality. Recurrence and tumorigenesis are attributed to a subpopulation of tumor-initiating glioma stem cells (GSCs) that are intrinsically resistant to therapy. Initiation and progression of gliomas have been linked to alterations in microRNA expression. Here, we report the identification of microRNA-138 (miR-138) as a molecular signature of GSCs and demonstrate a vital role for miR-138 in promoting growth and survival of bona fide tumor-initiating cells with self-renewal potential. Sequence-specific functional inhibition of miR-138 prevents tumorsphere formation in vitro and impedes tumorigenesis in vivo. We delineate the components of the miR-138 regulatory network by loss-of-function analysis to identify specific regulators of apoptosis. Finally, the higher expression of miR-138 in GSCs compared to non-neoplastic tissue and association with tumor recurrence and survival highlights the clinical significance of miR-138 as a prognostic biomarker and a therapeutic target for treatment of malignant gliomas.

Tumour suppressor Fus1 provides a molecular link between inflammatory response and mitochondrial homeostasis

Fus1, encoded by a 3p21.3 tumour suppressor gene, is down-regulated, mutated or lost in the majority of inflammatory thoracic malignancies. The mitochondrial localization of Fus1 stimulated us to investigate how Fus1 modulates inflammatory response and mitochondrial function in a mouse model of asbestos-induced peritoneal inflammation. Asbestos treatment resulted in a decreased Fus1 expression in wild-type (WT) peritoneal immune cells, suggesting that asbestos exposure may compromise the Fus1-mediated inflammatory response. Untreated Fus1(-/-) mice had an ~eight-fold higher proportion of peritoneal granulocytes than Fus1(+/+) mice, pointing at ongoing chronic inflammation. Fus1(-/-) mice exhibited a perturbed inflammatory response to asbestos, reflected in decreased immune organ weight and peritoneal fluid protein concentration, along with an increased proportion of peritoneal macrophages. Fus1(-/-) immune cells showed augmented asbestos-induced activation of key inflammatory, anti-oxidant and genotoxic stress response proteins ERK1/2, NFκB, SOD2, γH2AX, etc. Moreover, Fus1(-/-) mice demonstrated altered dynamics of pro- and anti-inflammatory cytokine expression, such as IFNγ, TNFα, IL-1A, IL-1B and IL-10. 'Late' response cytokine Ccl5 was persistently under-expressed in Fus1(-/-) immune cells at both basal and asbestos-activated states. We observed an asbestos-related difference in the size of CD3(+) CD4(-) CD8(-) DN T cell subset that was expanded four-fold in Fus1(-/-) mice. Finally, we demonstrated Fus1-dependent basal and asbestos-induced changes in major mitochondrial parameters (ROS production, mitochondrial potential and UCP2 expression) in Fus1(-/-) immune cells and in Fus1-depleted cancer cells, thus supporting our hypothesis that Fus1 establishes its immune- and tumour-suppressive activities via regulation of mitochondrial homeostasis.

Genetic and epigenetic analysis of non-small cell lung cancer with NotI-microarrays

This study aimed to clarify genetic and epigenetic alterations that occur during lung carcinogenesis and to design perspective sets of newly identified biomarkers. The original method includes chromosome 3 specific NotI-microarrays containing 180 NotI clones associated with genes for hybridization with 40 paired normal/tumor DNA samples of primary lung tumors: 28 squamous cell carcinomas (SCC) and 12 adenocarcinomas (ADC). The NotI-microarray data were confirmed by qPCR and bisulfite sequencing analyses. Forty-four genes showed methylation and/or deletions in more than 15% of non-small cell lung cancer (NSCLC) samples. In general, SCC samples were more frequently methylated/deleted than ADC. Moreover, the SCC alterations were observed already at stage I of tumor development, whereas in ADC many genes showed tumor progression specific methylation/deletions. Among genes frequently methylated/deleted in NSCLC, only a few were already known tumor suppressor genes: RBSP3 (CTDSPL), VHL and THRB. The RPL32, LOC285205, FGD5 and other genes were previously not shown to be involved in lung carcinogenesis. Ten methylated genes, i.e., IQSEC1, RBSP3, ITGA 9, FOXP1, LRRN1, GNAI2, VHL, FGD5, ALDH1L1 and BCL6 were tested for expression by qPCR and were found downregulated in the majority of cases. Three genes (RBSP3, FBLN2 and ITGA9) demonstrated strong cell growth inhibition activity. A comprehensive statistical analysis suggested the set of 19 gene markers, ANKRD28, BHLHE40, CGGBP1, RBSP3, EPHB1, FGD5, FOXP1, GORASP1/TTC21, IQSEC1, ITGA9, LOC285375, LRRC3B, LRRN1, MITF, NKIRAS1/RPL15, TRH, UBE2E2, VHL, WNT7A, to allow early detection, tumor progression, metastases and to discriminate between SCC and ADC with sensitivity and specificity of 80-100%.

Analysis of protein-protein interaction using proteinchip array-based SELDI-TOF mass spectrometry

Protein-protein interactions are key elements in the assembly of cellular regulatory and signaling protein complexes that integrate and transmit signals and information in controlling and regulating various cellular processes and functions. Many conventional methods of studying protein-protein interaction, such as the immuno-precipitation and immuno-blotting assay and the affinity-column pull-down and chromatographic analysis, are very time-consuming and labor intensive and lack accuracy and sensitivity. We have developed a simple, rapid, and sensitive assay using a ProteinChip array and SELDI-TOF mass spectrometry to analyze protein-protein interactions and map the crucial elements that are directly involved in these interactions. First, a purified "bait" protein or a synthetic peptide of interest is immobilized onto the preactivated surface of a PS10 or PS20 ProteinChip and the unoccupied surfaces on the chip are protected by application of a layer ethanolamine to prevent them from binding to other non-interactive proteins. Then, the target-containing cellular protein lysate or synthetic peptide containing the predicted amino acid sequence of protein-interaction motif is applied to the protected array with immobilized bait protein/peptide. The nonspecific proteins/peptides are washed off under various stringent conditions and only the proteins specifically interacting with the bait protein/peptide remain on the chip. Last, the captured interacting protein/peptide complexes are then analyzed by SELDI-TOF mass spectrometry and their identities are confirmed by their predicted distinctive masses. This method can be used to unambiguously detect the specific protein-protein interaction of known proteins/peptides, to easily identify potential cellular targets of proteins of interest, and to accurately analyze and map the structural elements of a given protein and its target proteins using synthetic peptides with the predicted potential protein interaction motifs.

A comprehensive map of the human urinary proteome

The study of the human urinary proteome has the potential to offer significant insights into normal physiology as well as disease pathology. The information obtained from such studies could be applied to the diagnosis of various diseases. The high sensitivity, resolution, and mass accuracy of the latest generation of mass spectrometers provides an opportunity to accurately catalog the proteins present in human urine, including those present at low levels. To this end, we carried out a comprehensive analysis of human urinary proteome from healthy individuals using high-resolution Fourier transform mass spectrometry. Importantly, we used the Orbitrap for detecting ions in both MS (resolution 60 000) and MS/MS (resolution 15 000) modes. To increase the depth of our analysis, we characterized both unfractionated as well as lectin-enriched proteins in our experiments. In all, we identified 1,823 proteins with less than 1% false discovery rate, of which 671 proteins have not previously been reported as constituents of human urine. This data set should serve as a comprehensive reference list for future studies aimed at identification and characterization of urinary biomarkers for various diseases.

Tumor suppressor gene-based nanotherapy: from test tube to the clinic

Cancer is a major health problem in the world. Advances made in cancer therapy have improved the survival of patients in certain types of cancer. However, the overall five-year survival has not significantly improved in the majority of cancer types. Major challenges encountered in having effective cancer therapy are development of drug resistance by the tumor cells, nonspecific cytotoxicity, and inability to affect metastatic tumors by the chemodrugs. Overcoming these challenges requires development and testing of novel therapies. One attractive cancer therapeutic approach is cancer gene therapy. Several laboratories including the authors' laboratory have been investigating nonviral formulations for delivering therapeutic genes as a mode for effective cancer therapy. In this paper the authors will summarize their experience in the development and testing of a cationic lipid-based nanocarrier formulation and the results from their preclinical studies leading to a Phase I clinical trial for nonsmall cell lung cancer. Their nanocarrier formulation containing therapeutic genes such as tumor suppressor genes when administered intravenously effectively controls metastatic tumor growth. Additional Phase I clinical trials based on the results of their nanocarrier formulation have been initiated or proposed for treatment of cancer of the breast, ovary, pancreas, and metastatic melanoma, and will be discussed.

microRNAs and lung cancer: tumors and 22-mers

Work over the last decade has revealed novel regulatory mechanisms in pathological disease states that are mediated by microRNAs and has inspired researchers to begin elucidating the specific roles of miRNAs in the regulation of genes involved in cancer development and progression. Recently, miRNAs have been explored as therapeutic targets and diagnostic markers of cancer. In this paper, we review recent advances in the study of miRNAs involved in tumorigenesis, focusing on miRNA regulation of genes that have been demonstrated to play critical roles in lung cancer development. We discuss miRNA regulation of genes that play critical roles in the process of malignant transformation, angiogenesis and tumor metastasis, the dysregulation of miRNA expression in cancer development, and the development of miRNA-based diagnostics and therapeutics.

Mechanisms of FUS1/TUSC2 deficiency in mesothelioma and its tumorigenic transcriptional effects

Background

FUS1/TUSC2 is a novel tumor suppressor located in the critical 3p21.3 chromosomal region frequently deleted in multiple cancers. We previously showed that Tusc2-deficient mice display a complex immuno-inflammatory phenotype with a predisposition to cancer. The goal of this study was to analyze possible involvement of TUSC2 in malignant pleural mesothelioma (MPM) - an aggressive inflammatory cancer associated with exposure to asbestos.

Methods

TUSC2 insufficiency in clinical specimens of MPM was assessed via RT-PCR (mRNA level), Representational Oligonucleotide Microarray Analysis (DNA level), and immunohistochemical evaluation (protein level). A possible link between TUSC2 expression and exposure to asbestos was studied using asbestos-treated mesothelial cells and ROS (reactive oxygen species) scavengers. Transcripional effects of TUSC2 in MPM were assessed through expression array analysis of TUSC2-transfected MPM cells.

Results

Expression of TUSC2 was downregulated in ~84% of MM specimens while loss of TUSC2-containing 3p21.3 region observed in ~36% of MPMs including stage 1 tumors. Exposure to asbestos led to a transcriptional suppression of TUSC2, which we found to be ROS-dependent. Expression array studies showed that TUSC2 activates transcription of multiple genes with tumor suppressor properties and down-regulates pro-tumorigenic genes, thus supporting its role as a tumor suppressor. In agreement with our knockout model, TUSC2 up-regulated IL-15 and also modulated more than 40 other genes (~20% of total TUSC2-affected genes) associated with immune system. Among these genes, we identified CD24 and CD274, key immunoreceptors that regulate immunogenic T and B cells and play important roles in systemic autoimmune diseases. Finally, clinical significance of TUSC2 transcriptional effects was validated on the expression array data produced previously on clinical specimens of MPM. In this analysis, 42 TUSC2 targets proved to be concordantly modulated in MM serving as disease discriminators.

Conclusion

Our data support immuno-therapeutic potential of TUSC2, define its targets, and underscore its importance as a transcriptional stimulator of anti-tumorigenic pathways.

miR-93, miR-98, and miR-197 regulate expression of tumor suppressor gene FUS1

FUS1 is a tumor suppressor gene located on human chromosome 3p21, and expression of Fus1 protein is highly regulated at various levels, leading to lost or greatly diminished tumor suppressor function in many lung cancers. Here we show that selected microRNAs (miRNA) interact with the 3'-untranslated region (3'UTR) of FUS1, leading to down-regulation of protein expression. Using computational methods, we first predicted that FUS1 is a target of three miRNAs, miR-93, miR-98, and miR-197, and then showed that exogenous overexpression of these miRNAs inhibited Fus1 protein expression. We then confirmed that the three miRNAs target the 3'UTR region of the FUS1 transcript and that individual deletion of the three miRNA target sites in the FUS1 3'UTR restores the expression level of Fus1 protein. We further found that miR-93 and miR-98 are expressed at higher levels in small-cell lung cancer cell lines (SCLC) than in non-small-cell lung cancer cell lines (NSCLC) and immortalized human bronchial epithelial cells (HBEC), and that miR-197 is expressed at higher levels in both SCLCs and NSCLCs than in HBECs. Finally, we found that elevated miR-93 and miR-197 expression is correlated with reduced Fus1 expression in NSCLC tumor specimens. These results suggest that the three miRNAs are negative regulators of Fus1 expression in lung cancers.

Lung cancer epigenetics and genetics

Lung cancer is the leading cause of cancer-related death and thus a major health problem. The efficiency of current treatment modalities for lung cancer depends strongly on the time of diagnosis, with better chances of survival if a tumor has been detected at an early stage. Thus, there is an urgent need for rapid and efficient early detection methods. Biomarkers represent a possible alternative to current, rather expensive, screening tools such as spiral computer tomography (CT), or may allow the identification of high risk groups for whom screening would be cost efficient. Although most lung cancers are the consequence of smoking, a substantial fraction of molecular-epidemiological studies point to high-prevalence, low-penetrance genetic polymorphisms as modifiers of environmental lung cancer risk. In the past the genomics field has also made significant advances in identifying genetic lesions that can now be harvested with the goal of identifying novel biomarkers for lung cancer. Furthermore, the importance of epigenetic changes that occur during lung cancer development has been reported, but has been underestimated in the past. Novel high-throughput, quantitative assays for the detection of DNA methylation or histone tail modifications are now applied, to search for alterations in the lung cancer genome and will identify novel cancer-related genes that may become attractive targets for treatment, provide new insight into the biology of lung cancers, and could also become useful biomarkers for the early detection of lung cancer in sputum, or may be used as prognostic markers. Thus, an integrative approach in lung cancer research combining epidemiological, genetic and epigenetic information becomes an important concept for the future.

Tumor suppressor FUS1 signaling pathway

FUS1 is a novel tumor suppressor gene identified in the human chromosome 3p21.3 region where allele losses and genetic alterations occur early and frequently for many human cancers. Expression of FUS1 protein is absent or reduced in the majority of lung cancers and premalignant lung lesions. Restoration of wt-FUS1 function in 3p21.3-deficient non-small cell lung carcinoma cells significantly inhibits tumor cell growth by induction of apoptosis and alteration of cell cycle kinetics. Here we present recent findings indicating that FUS1 induces apoptosis through the activation of the intrinsic mitochondrial-dependent and Apaf-1-associated pathways and inhibits the function of protein tyrosine kinases including EGFR, PDGFR, AKT, c-Abl, and c-Kit. Intravenous administration of a nanoparticle encapsulated FUS1 expression plasmid effectively delivers FUS1 to distant tumor sites and mediates an antitumor effect in orthotopic human lung cancer xenograft models. This approach is the rationale for an ongoing FUS1-nanoparticle-mediated gene delivery clinical trial for the treatment of lung cancer.

Activated c-Abl tyrosine kinase in malignant solid tumors

Mutant forms of the c-ABL gene are well known to be involved in hematopoietic malignancies such as chronic myeloid leukemia (CML). CML patients possess a fused BCR-ABL gene that activates the Abl tyrosine kinase domain within Bcr-Abl. In general fusion proteins that cause oligomerization of Abl lead to activation of its tyrosine kinase activity. In this review, we highlight recent discoveries indicating that the activated c-Abl tyrosine kinase, not as a fusion protein, plays an important role in malignant solid tumors of lung and breast.

The expression of BIRC5 is correlated with loss of specific chromosomal regions in breast carcinomas

Expression of BIRC5 (survivin), a member of the inhibitor of apoptosis protein (IAP) family, is elevated in fetal tissues and in various human cancers. Mechanisms up-regulating BIRC5 in cancer are poorly understood. Here, we show that overexpression of BIRC5 induces a high proliferation level in MCF-7 breast tumor cells. In a population of 191 breast carcinomas, BIRC5 expression is not affected by BIRC5 promoter polymorphism at -31, or BIRC5 gene copy number. However, a significant correlation was found between expression of demethylase (dMTase) and expression of BIRC5. In addition, among 13 chromosomal regions tested for allelic loss [loss of heterozygosity (LOH)], two regions close to D3S1478 and D6S264 were related to BIRC5 expression. In tumors with LOH at D3S1478 and/or D6S264, BIRC5 expression was significantly increased. These regions have been suggested to harbor tumor suppressor genes and/or common fragile sites that may play a role in increasing genetic instability. These results suggest that genes located near D3S1478 and D6S264 might work by inhibiting, directly or indirectly, BIRC5 expression and thus their loss leads to its up-regulation. In addition, BIRC5 expression may induce breast tumor proliferation by promoting genetic instability. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat.

The tumor suppressor gene DLEC1 is frequently silenced by DNA methylation in hepatocellular carcinoma and induces G1 arrest in cell cycle

BACKGROUND/AIMS

The chromosome locus 3p21.3 is a "hot-spot" for chromosomal aberrations and loss of heterozygosity in cancers. The 35 genes mapped to the AP20 subregion of this locus were screened for their expression to identify candidate tumor suppressor genes. DLEC1 was selected for further characterization in primary hepatocellular carcinomas and cell lines.

METHODS

RT-PCR and methylation-specific PCR were performed to examine the expression and methylation. Stable clones with DLEC1 overexpression were established to analyze cell proliferation and cell cycle.

RESULTS

DLEC1 was silenced and hypermethylated in 9 of 11 cell lines examined. Treatment with 5-aza-2'-deoxycytidine reversed the methylation and restored DLEC1 expression. The correlation between hypermethylation and expression was also demonstrated in 10 pairs of hepatocellular carcinoma and adjacent normal tissues (t-test, p<0.05). Hypermethylation of DLEC1 was detected in 70.6% of tumors, compared to 10.3% in normal tissues (n=68, p<0.001, chi(2)). Of interest, DLEC1 methylation was associated with the AJCC staging of the tumors (p=0.036, chi(2)). DLEC1 over-expression in cell lines decreased colony formation, cell growth and cell size, and induced a G1 arrest in cell cycle.

CONCLUSIONS

Our data indicate that DLEC1 is a candidate tumor suppressor gene that plays an important role in the development and progression of hepatocellular carcinoma.

Expression of alpha CP-4 inhibits cell cycle progression and suppresses tumorigenicity of lung cancer cells

The protein alpha CP-4 (also known as hnRNP E4) is an RNA binding protein encoded by a gene at 3p21, one of the most common altered regions in lung cancer. It has been proposed that alpha CP-4 may function as a lung tumor suppressor. Lack of alpha CP-4 expression is frequent in highly proliferative lung tumors and correlates with alpha CP-4 allele losses. The aim of this study was to evaluate the effect of alpha CP-4 on the tumorigenic capacity of lung cancer cells. alpha CP-4 expression was induced by transient transfection or stable infection with recombinant retroviruses. Induction of alpha CP-4 expression caused cell cycle arrest in G(2)/M in 3 out of the 7 lung cancer cell lines studied, while no effect on apoptosis was observed. Anchorage-independent growth and invasion capacity of H1299 cells were significantly reduced by alpha CP-4 induction. Tumorigenicity of H1299 cells in nude mice was greatly inhibited by the expression of alpha CP-4. Moreover, induction of alpha CP-4 expression in already established tumors resulted in a sudden growth arrest. Immunocytochemistry analysis of the xenograft tumors revealed an in vivo effect of alpha CP-4 on cell proliferation and no effect on apoptosis. Finally, alpha CP-4 showed a subcellular localization different from alpha CP-4a, a splice variant that does not affect cell proliferation. In conclusion, expression of alpha CP-4 can inhibit proliferation and tumorigenesis of lung cancer cells, both in vivo and in vitro, by delaying the progression of the cell cycle.

Loss and reduction of FUS1 protein expression is a frequent phenomenon in the pathogenesis of lung cancer

PURPOSE

FUS1, a novel tumor-suppressor gene located in the chromosome 3p21.3 region, may play an important role in lung cancer development. Currently, FUS1-expressing nanoparticles have been developed for treating patients with lung cancer. However, the expression of Fus1 protein has not been examined in a large series of lung cancers and their sequential preneoplastic lesions.

EXPERIMENTAL DESIGN

Using tissue microarrays, we examined Fus1 immunohistochemical expression in 281 non-small cell lung carcinoma (NSCLC) and 22 small cell lung carcinoma tissue specimens and correlated the findings with patients' clinicopathologic features. To investigate the expression of Fus1 in the early sequential pathogenesis of NSCLC, we studied Fus1 expression in 211 histologically normal and mildly abnormal bronchial epithelia, and 118 bronchial and alveolar preneoplastic lesions obtained from patients with lung cancer.

RESULTS

Loss and reduction of expression was detected in 82% of NSCLCs and 100% of small cell lung carcinomas. In NSCLCs, loss of Fus1 immunohistochemical expression was associated with significantly worse overall survival. Bronchial squamous metaplastic and dysplastic lesions expressed significantly lower levels of Fus1 compared with normal (P = 0.014 and 0.047, respectively) and hyperplastic (P = 0.013 and 0.028, respectively) epithelia.

CONCLUSIONS

Our findings show a high frequency of Fus1 protein loss and reduction of expression in lung cancer, and suggests that this reduction may play an important role in the early pathogenesis of lung squamous cell carcinoma. These findings support the concept that FUS1 gene and Fus1 protein abnormalities could be used to develop new strategies for molecular cancer therapy for a significant subset of lung tumors.

New molecularly targeted therapies for lung cancer

Lung cancer is the leading cause of cancer death worldwide. The disease is particularly difficult to detect, and patients often present at an advanced stage. Current treatments have limited effectiveness, and unfortunately, the prognosis remains poor. Recent insights into the molecular pathogenesis and biologic behavior of lung cancer have led to the development of rationally designed methods of early detection, prevention, and treatment of this disease. This article will review the important clinical implications of these advances, with a focus on new molecularly targeted therapies currently in development.

Evaluation of the 3p21.3 tumour-suppressor gene cluster

Deletions of the 3p21.3 region are a frequent and early event in the formation of lung, breast, kidney and other cancers. Intense investigation of allelic losses and the discovery of overlapping homozygous deletions in lung and breast tumour-cell lines have defined a minimal critical 120 kb deletion region containing eight genes and likely to harbor one or more tumour-suppressor genes (TSGs). The candidate genes are HYAL2, FUS1, Ras-associated factor 1 (RASSF1), BLU/ZMYND10, NPR2L, 101F6, PL6 and CACNA2D2. Recent research indicates that several of these genes can suppress the growth of lung and other tumour cells. Furthermore, some genes (RASSF1A and BLU/ZMYND10) are very frequently inactivated by non-classical mechanisms such as promoter hypermethylation resulting in loss of expression. These data indicate that the 120 kb critical deletion region at 3p21.3 may represent a TSG cluster with preferential inactivation of particular genes depending on tumour type. The eight genes within this region and their potential role in cancer will be the focus of this review.

Enhancement of antitumor activity of cisplatin in human lung cancer cells by tumor suppressor FUS1

FUS1 is a novel tumor suppressor gene located in the human chromosome 3p21.3 region. We previously showed that restoration of FUS1 function in 3p21.3-deficient human non-small-cell lung cancer (NSCLC) cells significantly inhibited tumor cell growth in vitro and in vivo. In this study, we evaluated the combined effects of the tumor suppressor FUS1 and the chemotherapeutic drug cisplatin on tumor cell growth and apoptosis induction in NSCLC cells, and explored the molecular mechanism of their mutual action. Exogenous expression of FUS1 by nanoparticle-mediated gene transfer sensitized the response of NSCLC cells to cisplatin, resulting in a 4- to 6-fold increase in tumor-suppressing activity. A systemic treatment with a combination of FUS1-nanoparticles and cisplatin in a human H322 lung cancer orthotopic xenograft mouse model dramatically enhanced the therapeutic efficacy of cisplatin. We also found that the FUS1-enhanced chemosensitivity is associated with the downregulation of MDM2, accumulation of p53 and activation of the Apaf-1-dependent apoptosis pathway. Our results demonstrated an important role of FUS1 in modulating chemosensitivity of lung cancer cells, and suggested that a proper combination of molecular therapeutics such as the proapoptotic tumor suppressor FUS1 and the conventional chemotherapeutic drugs such as cisplatin may be an efficient treatment strategy for human lung cancer.

Molecular pathogenesis of early-stage non-small cell lung cancer and a proposal for tissue banking to facilitate identification of new biomarkers

Non-small cell lung carcinoma (NSCLC) is one of the leading causes of death from cancer in both Eastern and Western countries. For patients with stage I NSCLC, full lobar or more extensive surgical resection is the treatment of choice. However, even among patients with surgically resected, stage I NSCLC, up to 30% of patients die of the disease within 5 years. At present, apart from clinical stage, there are no established cancer-specific clinical variables or biomarkers that reliably identify individuals at increased risk of death after surgical resection-individuals who could be candidates for adjuvant therapy or alternative management strategies. At a recent international workshop, participants discussed a clinical trial to compare radiation therapy with surgery among patients with stage I NSCLC. This study offers the opportunity to prospectively obtain, bank, and analyze tissue and other clinical specimens, which should facilitate the identification of new biomarkers for early detection, prognosis, and therapy in lung cancer.

Oncogenic activation of c-Abl in non-small cell lung cancer cells lacking FUS1 expression: inhibition of c-Abl by the tumor suppressor gene product Fus1

In lung cancer, frequent loss of one allele of chromosome 3p is seen in both small cell lung cancer and non-small cell lung cancer (NSCLC), providing evidence of tumor suppressor genes (TSGs) in this chromosomal region. The mechanism of Fus1 tumor suppressor activity is unknown. We have found that a Fus1 peptide inhibits the Abl tyrosine kinase in vitro (IC(50) 35 microM). The inhibitory Fus1 sequence was derived from a region that was deleted in a mutant FUS1 gene (FUS1 (1-80)) detected in some lung cancer cell lines. Importantly, a stearic acid-modified form of this peptide was required for the inhibition, but stearic acid alone was not inhibitory. Two NSCLC cell lines, which lack expression of wild-type Fus1, contain activated c-Abl. Forced expression of an inducible FUS1 cDNA in H1299 NSCLC cells decreased levels of activated c-Abl and inhibited its tyrosine kinase activity. Similarly, treatment of c-Abl immune complexes with the inhibitory Fus1 peptide also reduced the level of c-Abl in these immune complexes. The size and number of colonies of the NSCLC cell line, H1,299, in soft agar was strongly inhibited by the Abl kinase inhibitor imatinib mesylate. Co-expression of FUS1 and c-ABL in COS1 cells blocked activation of c-Abl tyrosine kinase. In contrast, co-expression of mutant FUS1 (1-80) with c-ABL had little inhibitory activity against c-Abl. These findings provide strong evidence that c-Abl is a possible target in NSCLC patients that have reduced expression of Fus1 in their tumor cells.

A translational view of the molecular pathogenesis of lung cancer

Molecular genetic studies of lung cancer have revealed that clinically evident lung cancers have multiple genetic and epigenetic abnormalities, including DNA sequence alterations, copy number changes, and aberrant promoter hypermethylation. Together, these abnormalities result in the activation of oncogenes and inactivation of tumor-suppressor genes. In many cases these abnormalities can be found in premalignant lesions and in histologically normal lung bronchial epithelial cells. Findings suggest that lung cancer develops through a stepwise process from normal lung epithelial cells towards frank malignancy, which usually occurs as a result of cigarette smoking. Lung cancer has a high morbidity because it is difficult to detect early and is frequently resistant to available chemotherapy and radiotherapy. New, rationally designed early detection, chemoprevention, and therapeutic strategies based on the growing understanding of the molecular changes important to lung cancer are under investigation. For example, methylated tumor DNA sequences in sputum or blood are being investigated for early detection screening, and new treatments that specifically target molecules such as vascular endothelial growth factor and the epidermal growth factor receptor are becoming available. Meanwhile, global gene expression signatures from individual tumors are showing potential as prognostic and therapeutic indicators, such that molecular typing of individual tumors for therapy selection is not far away. Finally, the recent development of a model system of immortalized human bronchial epithelial cells, along with a paradigm shift in the conception of cancer stem cells, promises to improve the situation for patients with lung cancer. These advances highlight the translation of molecular discoveries on lung cancer pathogenesis from the laboratory to the clinic.

Autoimmunity, spontaneous tumourigenesis, and IL-15 insufficiency in mice with a targeted disruption of the tumour suppressor gene Fus1

The Fus1 gene resides in the critical 3p21.3 human chromosomal region deleted in lung and breast cancers. Recently, the tumour suppressor properties of Fus1 were confirmed experimentally by intra-tumoural administration of Fus1 that suppressed experimental lung metastasis in mice. We generated Fus1-deficient mice that were viable, fertile, and demonstrated a complex immunological phenotype. Animals with a disrupted Fus1 gene developed signs of autoimmune disease, such as vasculitis, glomerulonephritis, anaemia, circulating autoantibodies, and showed an increased frequency of spontaneous vascular tumours. Preliminary analysis of immune cell populations revealed a consistent defect in NK cell maturation in Fus1 null mice that correlated with changes in the expression of IL-15. Injection of IL-15 into Fus1 knockout mice completely rescued the NK cell maturation defect. Based on these results, we propose the hypothesis that Fus1 deficiency affects NK cell maturation through the reduction of IL-15 production but does not directly alter their developmental capacity. Since acquired immunity was not affected in Fus1-deficient animals, we suggest a relationship between the Fus1 protein and the regulation of innate immunity via IL-15 production. The increased frequency of spontaneous cancers and the development of an autoimmune syndrome in Fus1 null mice imply that these mice could serve as a model for studying molecular mechanisms of anti-tumour immunity and autoimmunity.

Synergistic tumor suppression by coexpression of FUS1 and p53 is associated with down-regulation of murine double minute-2 and activation of the apoptotic protease-activating factor 1-dependent apoptotic pathway in human non-small cell lung cancer cells

FUS1 is a novel tumor suppressor gene identified in human chromosome 3p21.3 region. Loss of expression and deficiency of posttranslational modification of FUS1 protein have been found in a majority of human lung cancers. Restoration of wild-type FUS1 in 3p21.3-deficient human lung cancer cells exhibited a potent tumor suppression function in vitro and in vivo. In this study, we evaluated the combined effects of FUS1 and tumor suppressor p53 on antitumor activity and explored the molecular mechanisms of their mutual actions in human non-small cell lung cancer (NSCLC) cells. We found that coexpression of FUS1 and p53 by N-[1-(2,3-dioleoyloxyl)propyl]-NNN-trimethylammoniummethyl sulfate:cholesterol nanoparticle-mediated gene transfer significantly and synergistically inhibited NSCLC cell growth and induced apoptosis in vitro. We also found that a systemic treatment with a combination of FUS1 and p53 nanoparticles synergistically suppressed the development and growth of tumors in a human H322 lung cancer orthotopic mouse model. Furthermore, we showed that the observed synergistic tumor suppression by FUS1 and p53 concurred with the FUS1-mediated down-regulation of murine double minute-2 (MDM2) expression, the accumulation and stabilization of p53 protein, as well as the activation of the apoptotic protease-activating factor 1 (Apaf-1)-dependent apoptotic pathway in human NSCLC cells. Our results therefore provide new insights into the molecular mechanism of FUS1-mediated tumor suppression activity and imply that a molecular therapy combining two or more functionally synergistic tumor suppressors may constitute a novel and effective strategy for cancer treatment.

High resolution tiling-path BAC array deletion mapping suggests commonly involved 3p21-p22 tumor suppressor genes in neuroblastoma and more frequent tumors

The recurrent loss of 3p segments in neuroblastoma suggests the implication of 1 or more tumor suppressor genes but thus far few efforts have been made to pinpoint their detailed chromosomal position. To achieve this goal, array-based comparative genomic hybridization was performed on a panel of 23 neuroblastoma cell lines and 75 primary tumors using a tiling-path bacterial artificial chromosome array for chromosome 3p. A total of 45 chromosome 3 losses were detected, including whole chromosome losses, large terminal deletions and interstitial deletions. The latter, observed in cell lines as well as a number of distal deletions detected in primary tumors, allowed us to demarcate 3 minimal regions of loss of 3.6 Mb [3p21.31-p21.2, shortest regions of overlap (SRO)1], 1.4 Mb (3p22.3-3p22.2, SRO2) and 3.8 Mb (3p25.3-p25.1, SRO3) in size. The present data significantly extend previous findings and now firmly establish critical regions on 3p implicated in neuroblastoma. Interestingly, the 2 proximal regions coincide with previously defined SROs on 3p21.3 in more frequent tumors including lung and breast cancer. As such, similar tumor suppressor genes may play a critical role in development or progression of a variety of neoplasms, including neuroblastoma.

Small-cell lung cancer

Small-cell lung carcinoma is an aggressive form of lung cancer that is strongly associated with cigarette smoking and has a tendency for early dissemination. Increasing evidence has implicated autocrine growth loops, proto-oncogenes, and tumour-suppressor genes in its development. At presentation, the vast majority of patients are symptomatic, and imaging typically reveals a hilar mass. Pathology, in most cases of samples obtained by bronchoscopic biopsy, should be undertaken by pathologists with pulmonary expertise, with the provision of additional tissue for immunohistochemical stains as needed. Staging should aim to identify any evidence of distant disease, by imaging of the chest, upper abdomen, head, and bones as appropriate. Limited-stage disease should be treated with etoposide and cisplatin and concurrent early chest irradiation. All patients who achieve complete remission should be considered for treatment with prophylactic cranial irradiation, owing to the high frequency of brain metastases in this disease. Extensive-stage disease should be managed by combination chemotherapy, with a regimen such as etoposide and cisplatin administered for four to six cycles. Thereafter, patients with progressive or recurrent disease should be treated with additional chemotherapy. For patients who survive long term, careful monitoring for development of a second primary tumour is necessary, with further investigation and treatment as appropriate.

Liposomal vector mediated delivery of the 3p FUS1 gene demonstrates potent antitumor activity against human lung cancer in vivo

Lung cancer is one of the leading causes of death in the world. The underlying cause for lung cancer has been attributed to various factors that include alteration and mutation in the tumor suppressor genes. Restoration of normal function of the tumor suppressor gene is a potential therapeutic strategy. Recent studies have identified a group of candidate tumor suppressor genes on human chromosome 3p21.3 that are frequently deleted in human lung and breast cancers. Among the various genes identified in the 3p21.3 region, we tested the antitumor activity of the FUS1 gene in two human non-small-cell lung cancer (NSCLC) xenografts in vivo. Intratumoral administration of FUS1 gene complexed to DOTAP:cholesterol (DOTAP:Chol) liposome into subcutaneous H1299 and A549 lung tumor xenograft resulted in significant (P = .02) inhibition of tumor growth. Furthermore, intravenous injections of DOTAP:Chol-FUS1 complex into mice bearing experimental A549 lung metastasis demonstrated significant (P = .001) decrease in the number of metastatic tumor nodules. Finally, lung tumor-bearing animals when treated with DOTAP:Chol-FUS1 complex demonstrate prolonged survival (median survival time: 80 days, P = .01) compared to control animals. This result demonstrates the potent tumor suppressive activity of the FUS1 gene and is a promising therapeutic agent for treatment of primary and disseminated human lung cancer.

Mouse models for human lung cancer

In recent years several new mouse models for lung cancer have been described. These include models for both non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). Tumorigenesis in these conditional mouse tumor models can be initiated in adult mice through Cre-recombinase-induced activation of oncogenic mutations in a subset of the cells. They present a marked improvement over mouse models that depend on carcinogen induction of tumors. These models permit us to study the consecutive steps involved in initiation and progression and allow us to address questions like the cell of origin, and the role of cancer stem cells in the maintenance of these tumors. They now need to be validated as suitable preclinical models for intervention studies in which questions with respect to therapy response and resistance can be addressed.

3p21.3 tumor suppressor cluster: prospects for translational applications

Chromosomal abnormalities at the 3p21.3 region, including homozygous deletions and loss of heterozygosity and expressional deficiencies in 3p21.3 genes including transcriptional silences by promoter hypermethylation, altered mRNA splicing and aberrant transcripts, and lost or defect protein translation and post-translational modifications, are frequently found in most human cancers. Inactivation of 3p21.3 genes in primary tumors affects a wide spectrum of key biological processes such as cell proliferation, cell cycle kinetics, signaling transduction, ion exchange and transportation, apoptosis and cell death, and demonstrates the molecular signatures of carcinogenesis. Restoration of defective 3p21.3 genes with several wild-type 3p21.3 genes suppresses tumor cell growth both in vitro and in vivo. These findings suggest several 3p21.3 genes as potential tumor suppressors and implicates these 3p21.3 genes for future development as biomarkers for the early detection and diagnosis of cancer, and as prognostic and therapeutic tools for cancer prevention and molecular cancer therapy.

Loss of heterozygosity of chromosome 3p21 is associated with mutant TP53 and better patient survival in non-small-cell lung cancer

Allelic loss of chromosome region 3p21.3 occurs early and frequently in non-small-cell lung cancer, and numerous tumor suppressor genes at this locus may be targets of inactivation. Using an incident case series study of non-small-cell lung cancer, we sought to determine the prevalence of loss of heterozygosity (LOH) in the 3p21.3 region and to examine the associations between this alteration and patient outcome, exposure to tobacco smoke, occupational asbestos exposure, and additional molecular alterations in these tumors. We examined LOH at 7 microsatellite markers in the chromosome 3p21.3 region, and LOH was present in at least one of the loci examined in 60% (156 of 258) of the tumors, with the prevalence of LOH at individual loci ranging from 15 to 56%. Occupational asbestos exposure and TP53 mutation were significantly associated with more extensive 3p21 LOH. In squamous cell carcinomas, measures of cumulative smoking dose were significantly lower in patients with LOH at 3p21, particularly in TP53 mutant tumors. Examining patient outcome, we found that in squamous cell carcinomas, having any LOH in this region was associated with a better overall survival (log-rank test, P < 0.04). Together, these results indicate that allelic loss at 3p21 can affect patient outcome, and that this loss may initially be related to carcinogen exposure, but that extension of this loss is related to TP53 mutation status and occupational asbestos exposure.