Progression of human bronchioloalveolar carcinoma to invasive adenocarcinoma is modeled in a transgenic mouse model of K-ras-induced lung cancer by loss of the TGF-β type II receptor

Development of an invasion score based on metastasis-related pathway activity profiles for identifying invasive molecular subtypes of lung adenocarcinoma

The invasive capacity of lung adenocarcinoma (LUAD) is an important factor influencing patients' metastatic status and survival outcomes. However, there is still a lack of suitable biomarkers to evaluate tumor invasiveness. LUAD molecular subtypes were identified by unsupervised consistent clustering of LUAD. The differences in prognosis, tumor microenvironment (TME), and mutation were assessed among different subtypes. After that, the invasion-related gene score (IRGS) was constructed by genetic differential analysis, WGCNA analysis, and LASSO analysis, then we evaluated the relationship between IRGS and invasive characteristics, TME, and prognosis. The predictive ability of the IRGS was verified by in vitro experiments. Next, the "oncoPredict" R package and CMap were used to assess the potential value of IRGS in drug therapy. The results showed that LUAD was clustered into two molecular subtypes. And the C1 subtype exhibited a worse prognosis, higher stemness enrichment activity, less immune infiltration, and higher mutation frequency. Subsequently, IRGS developed based on molecular subtypes demonstrated a strong association with malignant characteristics such as invasive features, higher stemness scores, less immune infiltration, and worse survival. In vitro experiments showed that the higher IRGS LUAD cell had a stronger invasive capacity than the lower IRGS LUAD cell. Predictive analysis based on the "oncoPredict" R package showed that the high IRGS group was more sensitive to docetaxel, erlotinib, paclitaxel, and gefitinib. Among them, in vitro experiments verified the greater killing effect of paclitaxel on high IRGS cell lines. In addition, CMap showed that purvalanol-a, angiogenesis-inhibitor, and masitinib have potential therapeutic effects in the high IRGS group. In summary we identified and analyzed the molecular subtypes associated with the invasiveness of LUAD and developed IRGS that can efficiently predict the prognosis and invasive ability of the tumor. IRGS may be able to facilitate the precision treatment of LUAD to some extent.

A novel HIF1α-STIL-FOXM1 axis regulates tumor metastasis

BACKGROUND

Metastasis is the major cause of morbidity and mortality in cancer that involves in multiple steps including epithelial-mesenchymal transition (EMT) process. Centrosome is an organelle that functions as the major microtubule organizing center (MTOC), and centrosome abnormalities are commonly correlated with tumor aggressiveness. However, the conclusive mechanisms indicating specific centrosomal proteins participated in tumor progression and metastasis remain largely unknown.

METHODS

The expression levels of centriolar/centrosomal genes in various types of cancers were first examined by in silico analysis of the data derived from The Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and European Bioinformatics Institute (EBI) datasets. The expression of STIL (SCL/TAL1-interrupting locus) protein in clinical specimens was further assessed by Immunohistochemistry (IHC) analysis and the oncogenic roles of STIL in tumorigenesis were analyzed using in vitro and in vivo assays, including cell migration, invasion, xenograft tumor formation, and metastasis assays. The transcriptome differences between low- and high-STIL expression cells were analyzed by RNA-seq to uncover candidate genes involved in oncogenic pathways. The quantitative polymerase chain reaction (qPCR) and reporter assays were performed to confirm the results. The chromatin immunoprecipitation (ChIP)-qPCR assay was applied to demonstrate the binding of transcriptional factors to the promoter.

RESULTS

The expression of STIL shows the most significant increase in lung and various other types of cancers, and is highly associated with patients' survival rate. Depletion of STIL inhibits tumor growth and metastasis. Interestingly, excess STIL activates the EMT pathway, and subsequently enhances cancer cell migration and invasion. Importantly, we reveal an unexpected role of STIL in tumor metastasis. A subset of STIL translocate into nucleus and associate with FOXM1 (Forkhead box protein M1) to promote tumor metastasis and stemness via FOXM1-mediated downstream target genes. Furthermore, we demonstrate that hypoxia-inducible factor 1α (HIF1α) directly binds to the STIL promoter and upregulates STIL expression under hypoxic condition.

CONCLUSIONS

Our findings indicate that STIL promotes tumor metastasis through the HIF1α-STIL-FOXM1 axis, and highlight the importance of STIL as a promising therapeutic target for lung cancer treatment.

Integrative network analysis of early-stage lung adenocarcinoma identifies aurora kinase inhibition as interceptor of invasion and progression

Here we focus on the molecular characterization of clinically significant histological subtypes of early-stage lung adenocarcinoma (esLUAD), which is the most common histological subtype of lung cancer. Within lung adenocarcinoma, histology is heterogeneous and associated with tumor invasion and diverse clinical outcomes. We present a gene signature distinguishing invasive and non-invasive tumors among esLUAD. Using the gene signatures, we estimate an Invasiveness Score that is strongly associated with survival of esLUAD patients in multiple independent cohorts and with the invasiveness phenotype in lung cancer cell lines. Regulatory network analysis identifies aurora kinase as one of master regulators of the gene signature and the perturbation of aurora kinases in vitro and in a murine model of invasive lung adenocarcinoma reduces tumor invasion. Our study reveals aurora kinases as a therapeutic target for treatment of early-stage invasive lung adenocarcinoma.

Construction and Analysis of Survival-Associated Competing Endogenous RNA Network in Lung Adenocarcinoma

Increasing evidence has shown that noncoding RNAs play significant roles in the initiation, progression, and metastasis of tumours via participating in competing endogenous RNA (ceRNA) networks. However, the survival-associated ceRNA in lung adenocarcinoma (LUAD) remains poorly understood. In this study, we aimed to investigate the regulatory mechanisms underlying ceRNA in LUAD to identify novel prognostic factors. mRNA, lncRNA, and miRNA sequencing data obtained from the GDC data portal were utilized to identify differentially expressed (DE) RNAs. Survival-related RNAs were recognized using univariate Kaplan-Meier survival analysis. We performed functional enrichment analysis of survival-related mRNAs using the clusterProfiler package of R and STRING. lncRNA-miRNA and miRNA-mRNA interactions were predicted based on miRcode, Starbase, and miRanda. Subsequently, the survival-associated ceRNA network was constructed for LUAD. Multivariate Cox regression analysis was used to identify prognostic factors. Finally, we acquired 15 DE miRNAs, 49 DE lncRNAs, and 843 DE mRNAs associated with significant overall survival. Functional enrichment analysis indicated that survival-related DE mRNAs were enriched in cell cycle. The survival-associated lncRNA-miRNA-mRNA ceRNA network was constructed using five miRNAs, 49 mRNAs, and 21 lncRNAs. Furthermore, seven hub RNAs (LINC01936, miR-20a-5p, miR-31-5p, TNS1, TGFBR2, SMAD7, and NEDD4L) were identified based on the ceRNA network. LINC01936 and miR-31-5p were found to be significant using the multifactorial Cox regression model. In conclusion, we successfully constructed a survival-related lncRNA-miRNA-mRNA ceRNA regulatory network in LUAD and identified seven hub RNAs, which provide novel insights into the regulatory molecular mechanisms associated with survival of LUAD, and identified two independent prognostic predictors for LUAD.

Advances in Lung Cancer Driver Genes Associated With Brain Metastasis

Brain metastasis, one of the common complications of lung cancer, is an important cause of death in patients with advanced cancer, despite progress in treatment strategies. Lung cancers with positive driver genes have higher incidence and risk of brain metastases, suggesting that driver events associated with these genes might be biomarkers to detect and prevent disease progression. Common lung cancer driver genes mainly encode receptor tyrosine kinases (RTKs), which are important internal signal molecules that interact with external signals. RTKs and their downstream signal pathways are crucial for tumor cell survival, invasion, and colonization in the brain. In addition, new tumor driver genes, which also encode important molecules closely related to the RTK signaling pathway, have been found to be closely related to the brain metastases of lung cancer. In this article, we reviewed the relationship between lung cancer driver genes and brain metastasis, and summarized the mechanism of driver gene-associated pathways in brain metastasis. By understanding the molecular characteristics during brain metastasis, we can better stratify lung cancer patients and alert those at high risk of brain metastasis, which helps to promote individual therapy for lung cancer.

Genomic Underpinnings of Tumor Behavior in In Situ and Early Lung Adenocarcinoma

Rationale: We have a limited understanding of the molecular underpinnings of early adenocarcinoma (ADC) progression. We hypothesized that the behavior of early ADC can be predicted based on genomic determinants.Objectives: To identify genomic alterations associated with resected indolent and aggressive early lung ADCs.Methods: DNA was extracted from 21 ADCs in situ (AISs), 27 minimally invasive ADCs (MIAs), and 54 fully invasive ADCs. This DNA was subjected to deep next-generation sequencing and tested against a custom panel of 347 cancer genes.Measurements and Main Results: Sequencing data was analyzed for associations among tumor mutation burden, frequency of mutations or copy number alterations, mutation signatures, intratumor heterogeneity, pathway alterations, histology, and overall survival. We found that deleterious mutation burden was significantly greater in invasive ADC, whereas more copy number loss was observed in AIS and MIA. Intratumor heterogeneity establishes early, as in AIS. Twenty-one significantly mutated genes were shared among the groups. Mutation signature profiling did not vary significantly, although the APOBEC signature was associated with ADC and poor survival. Subclonal KRAS mutations and a gene signature consisting of PIK3CG, ATM, EPPK1, EP300, or KMT2C mutations were also associated with poor survival. Mutations of KRAS, TP53, and NF1 were found to increase in frequency from AIS and MIA to ADC. A cancer progression model revealed selective early and late drivers.Conclusions: Our results reveal several genetic driver events, clonality, and mutational signatures associated with poor outcome in early lung ADC, with potential future implications for the detection and management of ADC.

Epidemiology of lung cancer and lung cancer screening programs in China and the United States

Lung cancer is a heterogeneous disease that is impacted by environmental exposures and by constitutional genetic or epigenetic susceptibilities to disease development and progression. The United States and China have distinct and diverse populations and geographic environmental exposures that contribute to unique patterns of lung cancer incidence and mortality. In this paper, the authors compare trends of incidence and mortality of lung cancer in the US and China, and the impact on lung cancer screening programs in the two countries. It is worth noting that the mortality of lung cancer in the US has decreased gradually while in China it is still increasing over recent years. While decreasing smoking prevalence and the impact of clean air legislation have helped to mitigate the trend in the US relative to China, the increasingly widespread implementation of lung cancer chest CT screening is expected to impact lung cancer incidence and mortality in both countries. Currently there are few studies to compare the environmental and genetic risk factors for US and Chinese populations with regards to lung cancer incidence and mortality. The authors discuss the impact of gender and exposure risks, mainly smoking and environmental pollutants. Of high importance is the incidence of lung cancer in never smokers that is significantly higher in China than in the United States; this is particularly notable in women. These data suggest inclusion of ambient air pollution exposure and gender into lung cancer risk prognostic models to better capture high-risk individuals, especially for non-smoking women.

Dysregulated Tgfbr2/ERK-Smad4/SOX2 Signaling Promotes Lung Squamous Cell Carcinoma Formation

Lung squamous cell carcinoma (SCC) is a common type of lung cancer. There is limited information on the genes and pathways that initiate lung SCC. Here, we report that loss of TGFβ type II receptor (Tgfbr2), frequently deleted in human lung cancer, led to predominant lung SCC development in Kras^G12D mice with a short latency, high penetrance, and extensive metastases. Tgfbr2-loss-driven lung SCCs resembled the salient features of human lung SCC, including histopathology, inflammatory microenvironment, and biomarker expression. Surprisingly, loss of Smad4, a key mediator of Tgfbr2, failed to drive lung SCC; instead, low levels of phosphorylated ERK1/2, a Smad-independent downstream effector of Tgfbr2, were tightly associated with lung SCC in both mouse and human. Mechanistically, inhibition of phosphorylated ERK1/2 significantly upregulated the expression of SOX2, an oncogenic driver of lung SCC, and cooperated with SMAD4 repression to elevate SOX2. Inhibition of ERK1/2 in Smad4^fl/fl ;Kras^G12D mice led to extensive lung SCC formation that resembled the SCC phenotype of Tgfbr2-deficient mice. Overall, we reveal a key role of ERK1/2 in suppressing SCC formation and demonstrate that dysregulated Tgfbr2/ERK-Smad4/SOX2 signaling drives lung SCC formation. We also present a mouse model of metastatic lung SCC that may be valuable for screening therapeutic targets. SIGNIFICANCE: This study sheds new light on the mechanisms underlying lung SCC formation driven by mutated Kras.

Activation of PPARγ in Myeloid Cells Promotes Progression of Epithelial Lung Tumors through TGFβ1

Lung cancer is a heterogeneous disease in which patient-specific treatments are desirable and the development of targeted therapies has been effective. Although mutations in KRAS are frequent in lung adenocarcinoma, there are currently no targeted agents against KRAS. Using a mouse lung adenocarcinoma cell line with a Kras mutation (CMT167), we previously showed that PPARγ activation in lung cancer cells inhibits cell growth in vitro yet promotes tumor progression when activated in myeloid cells of the tumor microenvironment. Here, we report that PPARγ activation in myeloid cells promotes the production of TGFβ1, which, in turn, acts on CMT167 cancer cells to increase migration and induce an epithelial-mesenchymal transition (EMT). Targeting TGFβ1 signaling in CMT167 cells prevented their growth and metastasis in vivo. Similarly, another mouse lung adenocarcinoma cell line with a Kras mutation, LLC, induced TGFβ1 in myeloid cells through PPARγ activation. However, LLC cells are more mesenchymal and did not undergo EMT in response to TGFβ1, nor did LLC require TGFβ1 signaling for metastasis in vivo. Converting CMT167 cells to a mesenchymal phenotype through overexpression of ZEB1 made them unresponsive to TGFβ1 receptor inhibition. The ability of TGFβ1 to induce EMT in lung tumors may represent a critical process in cancer progression. We propose that TGFβ receptor inhibition could provide an additional treatment option for KRAS-mutant epithelial lung tumors.Implications: This study suggests that TGFβ receptor inhibitors may be an effective therapy in a subset of KRAS-mutant patients with non-small cell lung cancer, which show an epithelial phenotype.

TGF-β receptors: In and beyond TGF-β signaling

Transforming growth factor β (TGF-β) plays an important role in normal development and homeostasis. Dysregulation of TGF-β responsiveness and its downstream signaling pathways contribute to many diseases, including cancer initiation, progression, and metastasis. TGF-β ligands bind to three isoforms of the TGF-β receptor (TGFBR) with different affinities. TGFBR1 and 2 are both serine/threonine and tyrosine kinases, but TGFBR3 does not have any kinase activity. They are necessary for activating canonical or noncanonical signaling pathways, as well as for regulating the activation of other signaling pathways. Another prominent feature of TGF-β signaling is its context-dependent effects, temporally and spatially. The diverse effects and context dependency are either achieved by fine-tuning the downstream components or by regulating the expressions and activities of the ligands or receptors. Focusing on the receptors in events in and beyond TGF-β signaling, we review the membrane trafficking of TGFBRs, the kinase activity of TGFBR1 and 2, the direct interactions between TGFBR2 and other receptors, and the novel roles of TGFBR3.

Human immunodeficiency virus Tat-TIP30 interaction promotes metastasis by enhancing the nuclear translocation of Snail in lung cancer cell lines

Lung cancer patients with human immunodeficiency virus (HIV) have a poorer prognosis than do patients without HIV infection. HIV1 Tat is a secreted viral protein that penetrates the plasma membrane and interacts with a number of proteins in non‐HIV‐infected cells. The loss of function of Tat‐interacting protein 30 (TIP30) has been linked to metastasis in non‐small cell lung cancer (NSCLC). However, it is unknown how the interaction of HIV1 Tat with TIP30 regulates the metastasis of NSCLC cells. In this study, the overexpression of TIP30 decreased tumor growth factor‐β‐induced epithelial‐to‐mesenchymal transition (EMT) and invasion of NSCLC cells, whereas the knockdown of TIP30 promoted EMT, invasion and stemness. Exposure to recombinant HIV1 Tat proteins promoted EMT and invasion. A mechanistic study showed that the interaction of HIV1 Tat with TIP30 blocked the binding of TIP30 to importin‐β, which is required for the nuclear translocation of Snail. Indeed, the loss of TIP30 promoted the nuclear translocation of Snail. In vivo studies demonstrated that the overexpression of TIP30 inhibited the metastasis of NSCLC cells. In contrast, the coexpression of HIV1 Tat and TIP30 diminished the inhibitory effect of TIP30 on metastasis. Immunohistochemistry confirmed that TIP30 overexpression reduced the nuclear localization of Snail, whereas the coexpression of HIV1 Tat and TIP30 increased nuclear Snail in metastatic tumors. In conclusion, the binding of HIV1 Tat to TIP30 enhanced EMT and metastasis by regulating the nuclear translocation of Snail. Targeting Tat‐interacting proteins may be a potential therapeutic strategy to prevent metastasis in NSCLC patients with HIV infection.

Expression of AMHR2 and C-KIT in cervical lesions in Uyghur Women of Xinjiang, China

BACKGROUND

Cervical cancer is one of the most common malignant tumors in women. Anti-Müllerian hormone receptor 2 (AMHR2) and C-Kit were two members of protein kinase which were reported increased in some cancers like ovarian carcinoma and breast cancer. The present study aimed to assess the expression of AMHR2 and c-Kit in cervical cancer of different differentiated degrees as well as in cervicitis sections.

METHODS

All the lesions were collected randomly during clinical observations in hospitals located in Xinjiang, China. Polymerase chain reaction (PCR) and immunohistochemical staining were used to detect AMHR2 and c-Kit expression in cervical samples from women who had been infected with human papilloma virus (HPV)16. The expression rate was compared between cervical cancer of well, moderately and poorly differentiated and cervicitis.

RESULTS

The average age of the patients was 45 years; ranged from 23 to 80. For AMHR2, all 17 cervicitis samples ranged from (++) to (++++), while cervical cancer showed 11 (+), 9 (++), 15 (+++),9 (++++), and 8 (-), which showed AMHR2 expression was lessen with the poorer of differentiation degree of cervical cancer (P < .05). For c-Kit, 18 cervicitis samples mainly expressed as (-) with none showed (+++) or (++++), while cervical cancer samples showed 7 (-), 6 (+), 1 (++), 2 (+++), and 8 (++++), which indicated c-Kit's expression increased with the reduction of cervical cancer's differentiation degree (P < .05).

CONCLUSION

AMHR2 might have some correlation with self defense of our body, while c-Kit might link with the potential invasive capacity of cervical cancer.

Comparative proteomics of a model MCF10A-KRasG12V cell line reveals a distinct molecular signature of the KRasG12V cell surface

Oncogenic Ras mutants play a major role in the etiology of most aggressive and deadly carcinomas in humans. In spite of continuous efforts, effective pharmacological treatments targeting oncogenic Ras isoforms have not been developed. Cell-surface proteins represent top therapeutic targets primarily due to their accessibility and susceptibility to different modes of cancer therapy. To expand the treatment options of cancers driven by oncogenic Ras, new targets need to be identified and characterized at the surface of cancer cells expressing oncogenic Ras mutants. Here, we describe a mass spectrometry-based method for molecular profiling of the cell surface using KRasG12V transfected MCF10A (MCF10A-KRasG12V) as a model cell line of constitutively activated KRas and native MCF10A cells transduced with an empty vector (EV) as control. An extensive molecular map of the KRas surface was achieved by applying, in parallel, targeted hydrazide-based cell-surface capturing technology and global shotgun membrane proteomics to identify the proteins on the KRasG12V surface. This method allowed for integrated proteomic analysis that identified more than 500 cell-surface proteins found unique or upregulated on the surface of MCF10A-KRasG12V cells. Multistep bioinformatic processing was employed to elucidate and prioritize targets for cross-validation. Scanning electron microscopy and phenotypic cancer cell assays revealed changes at the cell surface consistent with malignant epithelial-to-mesenchymal transformation secondary to KRasG12V activation. Taken together, this dataset significantly expands the map of the KRasG12V surface and uncovers potential targets involved primarily in cell motility, cellular protrusion formation, and metastasis.

Transcriptomic Microenvironment of Lung Adenocarcinoma

Background: Tissues surrounding tumors are increasingly studied to understand the biology of cancer development and identify biomarkers.Methods: A unique geographic tissue sampling collection was obtained from patients that underwent curative lobectomy for stage I pulmonary adenocarcinoma. Tumor and nontumor lung samples located at 0, 2, 4, and 6 cm away from the tumor were collected. Whole-genome gene expression profiling was performed on all samples (n = 5 specimens × 12 patients = 60). Analyses were carried out to identify genes differentially expressed in the tumor compared with adjacent nontumor lung tissues at different distances from the tumor as well as to identify stable and transient genes in nontumor tissues with respect to tumor proximity.Results: The magnitude of gene expression changes between tumor and nontumor sites was similar with increasing distance from the tumor. A total of 482 up- and 843 downregulated genes were found in tumors, including 312 and 566 that were consistently differentially expressed across nontumor sites. Twenty-nine genes induced and 34 knocked-down in tumors were also identified. Tumor proximity analyses revealed 15,700 stable genes in nontumor lung tissues. Gene expression changes across nontumor sites were subtle and not statistically significant.Conclusions: This study describes the transcriptomic microenvironment of lung adenocarcinoma and adjacent nontumor lung tissues collected at standardized distances relative to the tumor.Impact: This study provides further insights about the molecular transitions that occur from normal tissue to lung adenocarcinoma and is an important step to develop biomarkers in nonmalignant lung tissues. Cancer Epidemiol Biomarkers Prev; 26(3); 389-96. ©2016 AACR.

Preclinical Modeling of KIF5B-RET Fusion Lung Adenocarcinoma

RET fusions have been found in lung adenocarcinoma, of which KIF5B-RET is the most prevalent. We established inducible KIF5B-RET transgenic mice and KIF5B-RET-dependent cell lines for preclinical modeling of KIF5B-RET-associated lung adenocarcinoma. Doxycycline-induced CCSP-rtTA/tetO-KIF5B-RET transgenic mice developed invasive lung adenocarcinoma with desmoplastic reaction. Tumors regressed upon suppression of KIF5B-RET expression. By culturing KIF5B-RET-dependent BaF3 (B/KR) cells with increasing concentrations of cabozantinib or vandetanib, we identified cabozantinib-resistant RET^V804L mutation and vandetanib-resistant-RET^G810A mutation. Among cabozantinib, lenvatinib, ponatinib, and vandetanib, ponatinib was identified as the most potent inhibitor against KIF5B-RET and its drug-resistant mutants. Interestingly, the vandetanib-resistant KIF5B-RET^G810A mutant displayed gain-of-sensitivity (GOS) to ponatinib and lenvatinib. Treatment of doxycycline-induced CCSP-rtTA/tetO-KIF5B-RET bitransgenic mice with ponatinib effectively induced tumor regression. These results indicate that KIF5B-RET-associated lung tumors are addicted to the fusion oncogene and ponatinib is the most effective inhibitor for targeting KIF5B-RET in lung adenocarcinoma. Moreover, this study finds a novel vandetanib-resistant RET^G810A mutation and identifies lenvatinib and ponatinib as the secondary drugs to overcome this vandetanib resistance mechanism. Mol Cancer Ther; 15(10); 2521-9. ©2016 AACR.

Anti-Müllerian Hormone Signaling Regulates Epithelial Plasticity and Chemoresistance in Lung Cancer

Anti-Müllerian hormone (AMH) and its type II receptor AMHR2, both previously thought to primarily function in gonadal tissue, were unexpectedly identified as potent regulators of transforming growth factor (TGF-β)/bone morphogenetic protein (BMP) signaling and epithelial-mesenchymal transition (EMT) in lung cancer. AMH is a TGF-β/BMP superfamily member, and AMHR2 heterodimerizes with type I receptors (ALK2, ALK3) also used by the type II receptor for BMP (BMPR2). AMH signaling regulates expression of BMPR2, ALK2, and ALK3, supports protein kinase B-nuclear factor κB (AKT-NF-κB) and SMAD survival signaling, and influences BMP-dependent signaling in non-small cell lung cancer (NSCLC). AMH and AMHR2 are selectively expressed in epithelial versus mesenchymal cells, and loss of AMH/AMHR2 induces EMT. Independent induction of EMT reduces expression of AMH and AMHR2. Importantly, EMT associated with depletion of AMH or AMHR2 results in chemoresistance but sensitizes cells to the heat shock protein 90 (HSP90) inhibitor ganetespib. Recognition of this AMH/AMHR2 axis helps to further elucidate TGF-β/BMP resistance-associated signaling and suggests new strategies for therapeutic targeting of EMT.

Methods to Study Metastasis in Genetically Modified Mice

Metastasis is often modeled by xenotransplantation of cell lines in immunodeficient mice. A wealth of information about tumor cell behavior in the new environment is obtained from these efforts. Yet by design, this approach is "tumor-centric," as it focuses on cell-autonomous determinants of human tumor dissemination in mouse tissues, in effect using the animal body as a sophisticated "Petri dish" providing nutrients and support for tumor growth. Transgenic or gene knockout mouse models of cancer allow the study of tumor spread as a systemic disease and offer a complimentary approach for studying the natural history of cancer. This introduction is aimed at describing the overall methodological approach to studying metastasis in genetically modified mice, with a particular focus on using animals with regulated expression of potent human oncogenes in the breast.

Update in Lung Cancer 2014

In the past 2 years, lung cancer research and clinical care have advanced significantly. Advancements in the field have improved outcomes and promise to lead to further reductions in deaths from lung cancer, the leading cause of cancer death worldwide. These advances include identification of new molecular targets for personalized targeted therapy, validation of molecular signatures of lung cancer risk in smokers, progress in lung tumor immunotherapy, and implementation of population-based lung cancer screening with chest computed tomography in the United States. In this review, we highlight recent research in these areas and challenges for the future.

Transcriptomic architecture of the adjacent airway field cancerization in non-small cell lung cancer

BACKGROUND

Earlier work identified specific tumor-promoting abnormalities that are shared between lung cancers and adjacent normal bronchial epithelia. We sought to characterize the yet unknown global molecular and adjacent airway field cancerization (FC) in early-stage non-small cell lung cancer (NSCLC).

METHODS

Whole-transcriptome expression profiling of resected early-stage (I-IIIA) NSCLC specimens (n = 20) with matched tumors, multiple cytologically controlled normal airways with varying distances from tumors, and uninvolved normal lung tissues (n = 194 samples) was performed using the Affymetrix Human Gene 1.0 ST platform. Mixed-effects models were used to identify differentially expressed genes among groups. Ordinal regression analysis was performed to characterize site-dependent airway expression profiles. All statistical tests were two-sided, except where noted.

RESULTS

We identified differentially expressed gene features (n = 1661) between NSCLCs and airways compared with normal lung tissues, a subset of which (n = 299), after gene set enrichment analysis, statistically significantly (P < .001) distinguished large airways in lung cancer patients from airways in cancer-free smokers. In addition, we identified genes (n = 422) statistically significantly and progressively differentially expressed in airways by distance from tumors that were found to be congruently modulated between NSCLCs and normal lung tissues. Furthermore, LAPTM4B, with statistically significantly increased expression (P < .05) in airways with shorter distance from tumors, was upregulated in human immortalized cells compared with normal bronchial epithelial cells (P < .001) and promoted anchorage-dependent and -independent lung cancer cell growth.

CONCLUSIONS

The adjacent airway FC comprises both site-independent profiles as well as gradient and localized airway expression patterns. Profiling of the airway FC may provide new insights into NSCLC oncogenesis and molecular tools for detection of the disease.

Molecular biology of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

Based on recent bench and clinical research, the treatment of lung cancer has been refined, with treatments allocated according to histology and specific molecular features. For example, targeting mutations such as epidermal growth factor receptor (EGFR) with tyrosine kinase inhibitors has been particularly successful as a treatment modality, demonstrating response rates in selected patients with adenocarcinoma tumors harboring EGFR mutations that are significantly higher than those for conventional chemotherapy. However, the development of new targeted therapies is, in part, highly dependent on an improved understanding of the molecular underpinnings of tumor initiation and progression, knowledge of the role of molecular aberrations in disease progression, and the development of highly reproducible platforms for high-throughput biomarker discovery and testing. In this article, we review clinically relevant research directed toward understanding the biology of lung cancer. The clinical purposes of this research are (1) to identify susceptibility variants and field molecular alterations that will promote the early detection of tumors and (2) to identify tumor molecular alterations that serve as therapeutic targets, prognostic biomarkers, or predictors of tumor response. We focus on research developments in the understanding of lung cancer somatic DNA mutations, chromosomal aberrations, epigenetics, and the tumor microenvironment, and how they can advance diagnostics and therapeutics.

Role of PTEN in basal cell derived lung carcinogenesis

Lung adenocarcinoma (AdC) and lung squamous cell carcinoma (SCC) are the most common non-small cell lung cancer (NSCLC) subtypes, however, most genetic mouse models of lung cancer produce predominantly, if not exclusively, AdC. Whether this is secondary to targeting mutations to the distal airway cells or to the use of activating Kras mutations that drive AdC formation is unknown. We previously showed that targeting Kras(G12D) activation and transforming growth factor β receptor type II (TGFβRII) deletion to airway basal cells via a keratin promoter induced formation of both lung AdC and SCC. In this study we assessed if targeting phosphatase and tensin homologue (PTEN) deletion to airway basal cells could initiate lung tumor formation or increase lung SCC formation. We found that PTEN deletion is capable of initiating both lung AdC and SCC formation when targeted to basal cells and although PTEN deletion is a weaker tumor initiator than Kras(G12D) with low tumor multiplicity and long latency, tumors initiated by PTEN deletion were larger and displayed more malignant conversion than Kras(G12D) initiated tumors. That PTEN deletion did not increase lung SCC formation compared to Kras(G12D) activation, suggests that the initiating genetic event does not dictate tumor histology when genetic alterations are targeted to a specific cell. These studies also confirm that basal cells of the conducting airway are capable of giving rise to multiple NSCLC tumor types.

Src-mediated morphology transition of lung cancer cells in three-dimensional organotypic culture

A fribotic tumor microenvironment promotes progression of cancer. In this study, we utilize a reconstituted basement membrane mimics Matrigel based three-dimensional organotypic culture (rBM 3-D) to investigate the mechanisms that mediate the tumor promoting effects of the fibrogenic mediators TGF-β1 and type I collagen (Col-1) on lung adenocarcinoma cells. Similar to normal alveolar epithelial cells, the well-differentiated lung adenocarcinoma cells in rBM 3-D culture undergo acinar morphogeneis that features polarized epithelial cell spheres with a single central lumen. Either TGF-β1 or Col-1 modestly distorts acinar morphogenesis. On the other hand, TGF-β1 and Col-1 synergistically induce a transition from acinar morphology into stellate morphology that is characteristic of invasive and metastatic cancer cells. Inhibition of the Src kinase activity abrogates induction of stellate morphology, activation of Akt and mTOR, and the expression of tumor promoting genes by TGF-β1 and Col-1. To a similar extent, pharmacological inhibition of mTOR abrogates the cellular responses to TGF-β1 and Col-1. In summary, we demonstrate that TGF-β1 and Col-1 promote stellate morphogenesis of lung cancer cells. Our findings further suggest that the Src-Akt-mTOR axis mediates stellate morphogenesis. These findings also indicate that rBM 3-D culture can serve as an ideal platform for swift and cost-effective screening of therapeutic candidates at the interface of the tumor and its microenvironment.

TGFβ1 induces apoptosis in invasive prostate cancer and bladder cancer cells via Akt-independent, p38 MAPK and JNK/SAPK-mediated activation of caspases

Recent findings indicate that advanced stage cancers shun the tumor suppressive actions of TGFβ and inexplicably utilize the cytokine as a tumor promoter. We investigated the effect of TGFβ1 on the survival and proliferation of invasive prostate (PC3) and bladder (T24) cancer cells. Our study indicated that TGFβ1 decreased cell viability and induced apoptosis in invasive human PC3 and T24 cells via activation of p38 MAPK-JNK-Caspase9/8/3 pathway. Surprisingly, no change in the phosphorylation of pro-survival Akt kinase was observed. We postulate that TGFβ1 pathway may be utilized for specifically targeting urological cancers without inflicting side effects on normal tissues.

Colorectal cancer migration and invasion initiated by microRNA-106a

MicroRNAs have been implicated in the regulation of several cellular signaling pathways of colorectal cancer (CRC) cells. Although emerging evidence proves that microRNA (miR)-106a is expressed highly in primary tumor and stool samples of CRC patients; whether or not miR-106a mediates cancer metastasis is unknown. We show here that miR-106a is highly expressed in metastatic CRC cells, and regulates cancer cell migration and invasion positively in vitro and in vivo. These phenotypes do not involve confounding influences on cancer cell proliferation. MiR-106a inhibits the expression of transforming growth factor-β receptor 2 (TGFBR2), leading to increased CRC cell migration and invasion. Importantly, miR-106a expression levels in primary CRCs are correlated with clinical cancer progression. These observations indicate that miR-106a inhibits the anti-metastatic target directly and results in CRC cell migration and invasion.

Genetic network and gene set enrichment analysis to identify biomarkers related to cigarette smoking and lung cancer

OBJECTIVES

Cigarette smoking is the most demonstrated risk factor for the development of lung cancer, while the related genetic mechanisms are still unclear.

METHODS

The preprocessed microarray expression dataset was downloaded from Gene Expression Omnibus database. Samples were classified according to the disease state, stage and smoking state. A new computational strategy was applied for the identification and biological interpretation of new candidate genes in lung cancer and smoking by coupling a network-based approach with gene set enrichment analysis.

MEASUREMENTS

Network analysis was performed by pair-wise comparison according to the disease states (tumor or normal), smoking states (current smokers or nonsmokers or former smokers), or the disease stage (stages I-IV). The most activated metabolic pathways were identified by gene set enrichment analysis.

RESULTS

Panels of top ranked gene candidates in smoking or cancer development were identified, including genes involved in cell proliferation and drug metabolism like cytochrome P450 and WW domain containing transcription regulator 1. Semaphorin 5A and protein phosphatase 1F are the common genes represented as major hubs in both the smoking and cancer related network. Six pathways, e.g. cell cycle, DNA replication, RNA transport, protein processing in endoplasmic reticulum, vascular smooth muscle contraction and endocytosis were commonly involved in smoking and lung cancer when comparing the top ten selected pathways.

CONCLUSION

New approach of bioinformatics for biomarker identification and validation can probe into deep genetic relationships between cigarette smoking and lung cancer. Our studies indicate that disease-specific network biomarkers, interaction between genes/proteins, or cross-talking of pathways provide more specific values for the development of precision therapies for lung.

Deletion of TGF-β signaling in myeloid cells enhances their anti-tumorigenic properties

By crossing LysM-Cre and TGF-β type II receptor (Tgfbr2) floxed mice we achieved specific deletion of Tgfbr2 in myeloid cells (Tgfbr2(MyeKO) mice). S.c.-injected (LLC, EL4-OVA) and implanted (MMTV-PyMT) carcinoma cells grow slower in Tgfbr2(MyeKO) mice. The number of CD45(+) cells in the tumor tissue was the same in both genotypes of mice, but upon analysis, the percentage of T cells (CD45(+)CD3(+)) in the KO mice was increased. By flow cytometry analysis, we did not detect any differences in the number and phenotype of TAMs, CD11b(+)Gr1(+), and DCs in Tgfbr2(MyeKO) compared with Tgfbr2(MyeWT) mice. ELISA and qRT-PCR data showed differences in myeloid cell functions. In Tgfbr2(MyeKO) TAMs, TNF-α secretion was increased, basal IL-6 secretion was down-regulated, TGF-β did not induce any VEGF response, and there was decreased MMP9 and increased MMP2 and iNOS expression. TGF-β did not have any effect on CD11b(+)Gr1(+) cells isolated from Tgfbr2(MyeKO) mice in the regulation of Arg, iNOS, VEGF, and CXCR4, and moreover, these cells have decreased suppressive activity relative to T cell proliferation. Also, we found that DCs from tumor tissue of Tgfbr2(MyeKO) mice have increased antigen-presented properties and an enhanced ability to stimulate antigen-specific T cell proliferation. We conclude that Tgfbr2 in myeloid cells has a negative role in the regulation of anti-tumorigenic functions of these cells, and deletion of this receptor decreases the suppressive function of CD11b(+)Gr1(+) cells and increases antigen-presenting properties of DCs and anti-tumorigenic properties of TAMs.

Loss of transforming growth factor beta type II receptor increases aggressive tumor behavior and reduces survival in lung adenocarcinoma and squamous cell carcinoma

PURPOSE

Lung adenocarcinoma and lung squamous cell carcinoma (SCC) are the most common non-small cell lung cancer (NSCLC) subtypes. This study was designed to determine whether reduced expression of TGFβ type II receptor (TGFβRII) promotes lung adenocarcinoma and SCC carcinogenesis.

EXPERIMENTAL DESIGN

We examined TGFβRII expression at the protein and mRNA levels in human NSCLC samples and assessed the relationship between TGFβRII expression and clinicopathologic parameters. To determine whether sporadic TGFβRII deletion in airway epithelial cells induces NSCLC formation, we targeted TGFβRII deletion alone and in combination with oncogenic Kras(G12D) to murine airways using a keratin 5 (K5) promoter and inducible Cre recombinase.

RESULTS

Reduced TGFβRII expression in human NSCLC is associated with male gender, smoking, SCC histology, reduced differentiation, increased tumor stage, increased nodal metastasis, and reduced survival. Homozygous or heterozygous TGFβRII deletion in mouse airway epithelia increases the size and number of Kras(G12D)-initiated adenocarcinoma and SCC. TGFβRII deletion increases proliferation, local inflammation, and TGFβ ligand elaboration; TGFβRII knockdown in airway epithelial cells increases migration and invasion.

CONCLUSIONS

Reduced TGFβRII expression in human NSCLC is associated with more aggressive tumor behavior and inflammation that is, at least partially, mediated by increased TGFβ1 expression. TGFβRII deletion in mouse airway epithelial cells promotes adenocarcinoma and SCC formation, indicating that TGFβRII loss plays a causal role in lung carcinogenesis. That TGFβRII shows haploid insufficiency suggests that a 50% TGFβRII protein reduction would negatively impact lung cancer prognosis.