[Show abstract][Hide abstract] ABSTRACT: Lineage transition in adenocarcinoma (ADC) and squamous cell carcinoma (SCC) of non-small cell lung cancer, as implicated by clinical observation of mixed ADC and SCC pathologies in adenosquamous cell carcinoma, remains a fundamental yet unsolved question. Here we provide in vivo evidence showing the transdifferentiation of lung cancer from ADC to SCC in mice: Lkb1-deficient lung ADC progressively transdifferentiates into SCC, via a pathologically mixed mAd-SCC intermediate. We find that reduction of lysyl oxidase (Lox) in Lkb1-deficient lung ADC decreases collagen disposition and triggers extracellular matrix remodelling and upregulates p63 expression, a SCC lineage survival oncogene. Pharmacological Lox inhibition promotes the transdifferentiation, whereas ectopic Lox expression significantly inhibits this process. Notably, ADC and SCC show differential responses to Lox inhibition. Collectively, our findings demonstrate the de novo transdifferentiation of lung ADC to SCC in mice and provide mechanistic insight that may have important implications for lung cancer treatment.
[Show abstract][Hide abstract] ABSTRACT: Liver kinase B1 (LKB1) genetic alteration in lung cancer involves not only point mutations and small deletion of several base pairs but also exonic loss. However, most of recent studies in LKB1 gene status only focus on point mutations and small deletion, and thus may underestimate the actual frequency of LKB1 genetic alteration in lung cancer. Thus, an integrative analysis of LKB1 genetic alteration is timely and important for providing a better estimate for the incidence of genetic alterations in this important tumor suppressor gene. One hundred and seven lung adenocarcinomas with more than 70% tumor have been analyzed for mutation of LKB1 as well as LKB1 large deletions detection by using multiplex ligation-dependent probe amplification analysis. These samples were also analyzed for EGFR, KRAS, HER2, BRAF, ALK, ROS1, and RET status in stepwise method. Among 107 lung adenocarcinomas analyzed, 29 (27.1%) harbored LKB1 genetic alteration. Twenty-three (21.5%) harbored LKB1 large exonic deletions and eight (7.48%) had LKB1 points mutations, two samples harbored both LKB1 large exonic deletions and point mutations. Eighty-seven samples (81.31%) harbored known driver mutations and 20 samples (18.69%) had no identifiable driver mutations. A high rate of LKB1 genetic alteration in Chinese lung adenocarcinomas is revealed by the integrative analysis of point mutation and exonic deletion. Moreover, LKB1 genetic alterations are concurrent with EGFR, KRAS, HER2, and CD74-ROS fusions.
Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 02/2014; 9(2):254-8. · 4.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Lung cancer is one of the most devastating diseases worldwide with high incidence and mortality. Hippo (Hpo) pathway is a conserved regulator of organ size in both Drosophila and mammals. Emerging evidence has suggested the significance of Hpo pathway in cancer development. In this study, we identify VGLL4 as a novel tumor suppressor in lung carcinogenesis through negatively regulating the formation of YAP-TEAD complex, the core component of Hpo pathway. Our data show that VGLL4 is frequently observed to be lowly expressed in both mouse and human lung cancer specimens. Ectopic expression of VGLL4 significantly suppresses the growth of lung cancer cells in vitro. More importantly, VGLL4 significantly inhibits lung cancer progression in de novo mouse model. We further find that VGLL4 inhibits the activity of the YAP-TEAD transcriptional complex. Our data show that VGLL4 directly competes with YAP in binding to TEADs and executes its growth-inhibitory function through two TDU domains. Collectively, our study demonstrates that VGLL4 is a novel tumor suppressor for lung cancer through negatively regulating the YAP-TEAD complex formation and thus the Hpo pathway.Cell Research advance online publication 24 January 2014; doi:10.1038/cr.2014.10.
[Show abstract][Hide abstract] ABSTRACT: Whether the Hippo pathway contributes to cell lineage transition under pathological conditions, especially tumorigenesis, remains largely unknown. Here we show that YAP, the major effector of the Hippo pathway, displays a distinct activation pattern in lung adenocarcinoma (ADC) and squamous cell carcinoma (SCC); YAP is initially activated by LKB1 loss in lung ADC, which upregulates ZEB2 expression and represses DNp63 transcription in a default manner. During transdifferentiation, YAP is inactivated, which in turn relieves ZEB2-mediated default repression of DNp63 and triggers squamous differentiation reprogramming. Disruption of the YAP barrier for phenotypic transition significantly accelerates squamous transdifferentiation, whereas constitutive YAP activation conversely inhibits this transition. More importantly, ectopic DNp63 expression rescues the inhibitory effect of YAP on squamous transdifferentiation. These findings have established YAP as an essential barrier for lung cancer cell fate conversion and provided a mechanism for regulating cancer plasticity, which might hold important implication for YAP-targeted therapies.
[Show abstract][Hide abstract] ABSTRACT: A fraction of lung adenocarcinomas harbor activating mutations in the HER2 kinase domain. HER2-targeted therapies have shown minimal benefit in molecularly unselected patients. We investigated clinical and potential molecular factors associated with HER2-mutant lung adenocarcinoma.
A total of 224 lung adenocarcinoma samples were examined for activating mutations in epidermal growth factor receptor (EGFR; exons 18-22), V-Ki-ras2 Kirsten rat sarcoma (KRAS; exons 2 and 3), and HER2 (exons 18-21) by direct sequencing. Gene copy number and protein expression of both EGFR and HER2 were further explored in samples harboring HER2 mutations using fluorescence in situ hybridization and immunohistochemistry, respectively.
The mutation rates of EGFR, KRAS, HER2 were 63.39% (142/224), 4.46% (10/224), and 3.57% (8/224), respectively. All mutations were mutually exclusive. All eight HER2 mutations occurred in never smokers and seven were in women. The HER2 mutation rate in samples without EGFR and KRAS mutations was 11.11% (8/72). Seven of eight HER2-mutated tumors showed HER2 copy number gains (CNGs) and five showed EGFR CNGs. All of the HER2-mutated samples showed either HER2 or EGFR CNGs. Gene amplification of HER2 and EGFR was mutually exclusive in HER2-mutated samples.
HER2 mutations in lung adenocarcinoma predominantly occurred in women and never smokers. Most HER2-mutated tumors showed HER2 CNGs. As all of the samples with HER2 mutation showed either HER2 or EGFR CNGs, these patients could potentially benefit from novel EGFR/HER2 dual or pan-erythroblastic leukemia viral oncogene homolog tyrosine kinase inhibitors.
Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 11/2011; 7(1):85-9. · 4.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The epidermal growth factor receptor (EGFR) gene status including tyrosine kinase domain somatic mutations, increased copy number, and protein overexpression are reported to be associated with response to EGFR tyrosine kinase inhibitors in patients with non-small cell lung cancer. The purpose of this study was to elucidate the prevalence of activated EGFR gene and the association between mutation, copy number, and protein overexpression.
In a cohort of consecutive patients with lung adenocarcinoma, polymerase chain reaction and direct sequencing (n = 89) were conducted through exons 18 to 21. Fluorescence in situ hybridization (FISH) (n = 89) and single-nucleotide polymorphism (SNP) array 6.0 (n = 77) were used to detect the gene copy number. The protein expression of EGFR was detected by standard immunohistochemistry (IHC) (n = 89).
Fifty-nine (66.3%) patients harbored somatic mutations of EGFR in tyrosine kinase domain, 55.1% were positive by IHC and 44.9% were positive by FISH, and 66.2% showed gain of copy number according to SNP array 6.0. EGFR somatic mutations are more common in women, never smokers, and tumors with better differentiation. Increased copy number detected by both FISH and SNP array 6.0 analysis is significantly correlated with mutations of EGFR.
The EGFR somatic mutation rate is significantly higher in Chinese patients with lung adenocarcinoma than western countries. Nevertheless, we found comparable FISH and IHC-positive rates between different ethnics. Considering that FISH may be affected by tumor heterogeneity and other factors, SNP array 6.0 analysis is a good alternative method to detect EGFR copy number variations.
Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 06/2011; 6(6):1016-21. · 4.55 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We previously showed that 90% (47 of 52; 95% CI, 0.79 to 0.96) of lung adenocarcinomas from East Asian never-smokers harbored well-known oncogenic mutations in just four genes: EGFR, HER2, ALK, and KRAS. Here, we sought to extend these findings to more samples and identify driver alterations in tumors negative for these mutations.
We have collected and analyzed 202 resected lung adenocarcinomas from never smokers seen at Fudan University Shanghai Cancer Center. Since mutations were mutually exclusive in the first 52 examined, we determined the status of EGFR, KRAS, HER2, ALK, and BRAF in stepwise fashion as previously described. Samples negative for mutations in these 5 genes were subsequently examined for known ROS1 fusions by RT-PCR and direct sequencing.
152 tumors (75.3%) harbored EGFR mutations, 12 (6%) had HER2 mutations, 10 (5%) had ALK fusions all involving EML4 as the 5' partner, 4 (2%) had KRAS mutations, and 2 (1%) harbored ROS1 fusions. No BRAF mutation were detected.
The vast majority (176 of 202; 87.1%, 95% CI: 0.82 to 0.91) of lung adenocarcinomas from never smokers harbor mutant kinases sensitive to available TKIs. Interestingly, patients with EGFR mutant patients tend to be older than those without EGFR mutations (58.3 Vs 54.3, P = 0.016) and patient without any known oncogenic driver tend to be diagnosed at a younger age (52.3 Vs 57.9, P = 0.013). Collectively, these data indicate that the majority of never smokers with lung adenocarcinoma could benefit from treatment with a specific tyrosine kinase inhibitor.
PLoS ONE 01/2011; 6(11):e28204. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To determine the proportion of lung adenocarcinomas from East Asian never-smokers who harbor known oncogenic driver mutations.
In this surgical series, 52 resected lung adenocarcinomas from never-smokers (< 100 cigarettes in a lifetime) at a single institution (Fudan University, Shanghai, China) were analyzed concurrently for mutations in EGFR, KRAS, NRAS, HRAS, HER2, BRAF, ALK, PIK3CA, TP53 and LKB1.
Forty-one tumors harbored EGFR mutations, three harbored EML4-ALK fusions, two harbored HER2 insertions, and one harbored a KRAS mutation. All mutations were mutually exclusive. Thus, 90% (47 of 52; 95% CI, 0.7896 to 0.9625) of lung adenocarcinomas from never-smokers were found to harbor well-known oncogenic mutations in just four genes. No BRAF, NRAS, HRAS, or LKB1 mutations were detected, while 15 had TP53 mutations. Four tumors contained PIK3CA mutations, always together with EGFR mutations.
To our knowledge, this study represents the first comprehensive and concurrent analysis of major recurrent oncogenic mutations found in a large cohort of lung adenocarcinomas from East Asian never-smokers. Since drugs are now available that target mutant EGFR, HER2, and ALK, respectively, this result indicates that prospective mutation testing in these patients should successfully assign a targeted therapy in the majority of cases.
Journal of Clinical Oncology 10/2010; 28(30):4616-20. · 18.04 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: LKB1 loss-of-function mutations, observed in ∼30% of human lung adenocarcinomas, contribute significantly to lung cancer malignancy progression. We show that lysyl oxidase (LOX), negatively regulated by LKB1 through mTOR-HIF-1α signaling axis, mediates lung cancer progression. Inhibition of LOX activity dramatically alleviates lung cancer malignancy progression. Up-regulated LOX expression triggers excess collagen deposition in Lkb1-deficient lung tumors, and thereafter results in enhanced cancer cell proliferation and invasiveness through activation of β1 integrin signaling. High LOX level and activity correlate with poor prognosis and metastasis. Our findings provide evidence of how LKB1 loss of function promotes lung cancer malignancy through remodeling of extracellular matrix microenvironment, and identify LOX as a potential target for disease treatment in lung cancer patients.
Proceedings of the National Academy of Sciences 10/2010; 107(44):18892-7. · 9.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Somatic LKB1 mutations are found in lung adenocarcinomas at different frequencies in Caucasian and East Asian (Japanese and Korean) populations. This study was designed to characterize the frequency of LKB1 mutations, their relationship to EGFR and KRAS mutations, and their associated clinicopathologic characteristics in Chinese patients.
Two hundred thirty-nine lung adenocarcinomas consecutively collected from October 2007 to July 2009 were dissected into 3 to 4 small (3 mm) pieces for histopathological analyses of tumor content. Genomic DNA and/or cDNA from 86 samples with more than 70% tumor content were used for sequencing of LKB1 (exons 1-9), EGFR (exons 18-21), and KRAS (exon 2). LKB1 germline mutation status was determined by sequencing of genomic DNA from matched histologically distant lung tissues that are histologically normal.
6.9% of lung adenocarcinomas harbored LKB1 somatic mutations. A total of 10.5% of patients had an LKB1 germline polymorphism, F354L. Interestingly, in two of these patients, tumors displayed loss of heterozygosity at this allele. EGFR kinase domain and KRAS mutations were found in 66.3% and 2.3% of Chinese lung adenocarcinomas, respectively. Concurrent LKB1 and EGFR somatic mutations were observed in one patient. Both KRAS-mutant tumors harbored LKB1 mutations.
These data provide important clinical and molecular characteristics of lung adenocarcinomas from Chinese patients.
Journal of thoracic oncology: official publication of the International Association for the Study of Lung Cancer 08/2010; 5(8):1130-5. · 4.55 Impact Factor