Impact of cigarette smoking on response to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors in lung adenocarcinoma with activating EGFR mutations

Objectives

The aim of this study is to evaluate the predictive impact of cigarette smoking on treatment outcomes of EGFR-tyrosine kinase inhibitors (TKIs) in lung adenocarcinoma patients with activating EGFR mutations.

Methods

We retrospectively analyzed 222 consecutive recurrent or unresectable lung adenocarcinoma patients who harbored activating EGFR mutations (exon 19 deletion or exon 21 L858R) and had received gefitinib or erlotinib. Detailed smoking histories were obtained from all patients according to a standard protocol.

Results

Of 222 EGFR-mutated patients, 65.3% were never-smokers, 19.8% were smokers with <30 pack-years, and 14.9% were smokers with ≥30 pack-years smoking dosage. The disease control rate (DCR) and objective response rate (ORR) of smokers with ≥30 pack-years were significantly lower than never-smokers and smokers with <30 pack-years (DCR, 78.8% vs. 93.1%, p = 0.016; ORR, 45.5% vs. 62.4%, p = 0.020). Smokers with ≥30 pack-years showed significantly shorter PFS than never-smokers (6.4 vs. 11.8 months, p = 0.001) and smokers with <30 pack-years (6.4 vs. 11.4 months, p = 0.033), as well as shorter overall survival from the time of metastatic diagnosis than never-smokers (33.6 vs. 46.2 months, p = 0.003). There was no survival difference between smokers with <30 pack-year and never smokers. In the multivariate analysis adjusted for age, sex, performance status, initial stage, and line of EGFR-TKI, the presence of smoking dosage ≥30 pack-years was an independent predictive factor for the disease progression to EGFR-TKIs (hazard ratio, 1.87; 95% confidence interval, 1.15–3.05; p = 0.012).

Conclusions

Cigarette smoking dosage of ≥30 pack-years is an independent negative predictive factor of EGFR-TKI treatment outcome in lung adenocarcinoma patients with activating EGFR mutations.     

Epidermal growth factor receptor tyrosine kinase inhibitors as initial therapy for non-small cell lung cancer: Focus on epidermal growth factor receptor mutation testing and mutation-positive patients

Activation of the epidermal growth factor receptor (EGFR) pathway has been implicated in tumorigenesis in non-small cell lung cancer (NSCLC), the most common type of lung cancer. As a result, EGFR has become a key focus for the development of personalized therapy, with several molecular biomarkers having been investigated as potential predictors of response with EGFR tyrosine kinase inhibitors (TKIs) in NSCLC (e.g., EGFR expression, EGFR gene copy gain, and EGFR mutations). Of these, activating mutations in EGFR have thus far given the most consistent results based on the available evidence from preclinical studies and clinical trials. In an attempt to identify patients who are most likely to benefit from treatment with EGFR TKIs, EGFR mutation testing is being increasingly utilized in clinical practice. Currently in the United States, no EGFR TKI or accompanying mutational test is approved for the identification and first-line treatment of patients with advanced NSCLC. However, the first-generation EGFR TKIs, erlotinib and gefitinib, as well as investigational ErbB family TKIs and EGFR mutation testing methods are being evaluated in this setting. This review will discuss EGFR mutation testing as a biomarker of response to EGFR TKIs and the evolution of EGFR mutational analysis in NSCLC. Completed and ongoing clinical trials evaluating currently available or investigational EGFR TKIs as first-line therapy in molecularly and clinically selected patients with NSCLC, with a focus on trials in patients whose tumors have EGFR mutations, will also be reviewed.     

Tumor-associated macrophages correlate with response to epidermal growth factor receptor-tyrosine kinase inhibitors in advanced non-small cell lung cancer

Our study investigated whether tumor-associated macrophages (TAMs) in advanced non-small cell lung cancer (NSCLC) are related to treatment response to epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) and may be a predictor of survival. Of 206 advanced NSCLC patients treated (first-line) with an EGFR-TKI at the study hospital from 2006 to 2009, 107 with adequate specimens for assessing CD68 immunohistochemistry as a marker of TAMs were assessed. After EGFR-TKI treatment, response was observed in 55 (51%) patients, and the median follow-up period was 13.5 months. Most TAMs were located in the tumor stroma (>95%) and positively costained with the M2 marker CD163. TAM counts were significantly higher in patients with progressive disease than in those without (p < 0.0001), a trend that remained in patients with known EGFR mutation status (n = 59) and those with wild-type EGFR (n = 20). High TAM counts, among other factors (e.g., wild-type EGFR), were significantly related to poor progression-free survival (PFS) and overall survival (OS) (all p < 0.0001 for TAMs). Multivariate Cox analyses showed that high TAM counts and EGFR mutations were both independent factors associated with PFS [odds ratio (OR), 8.0; 95% confidence interval (CI), 2.87-22.4; p = 0.0001 and OR, 0.03; 95% CI, 0.003-0.31; p = 0.003, respectively] and OS (OR, 2.641; 95% CI, 1.08-6.5; p = 0.03 and OR, 0.14; 95% CI, 0.03-0.56; p = 0.006, respectively). TAMs are related to treatment response irrespective of EGFR mutation and can independently predict survival in advanced NSCLC treated with an EGFR-TKI.     

Acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors in EGFR-mutant non-small cell lung cancer: A new era begins

The discovery of mutated oncogenes has opened up a new era for the development of more effective treatments for non-small cell lung cancer patients (NSCLC) harbouring EGFR mutations. However, patients with EGFR-activating mutation ultimately develop acquired resistance (AR). Several studies have identified some of the mechanisms involved in the development of AR to EGFR tyrosine kinase inhibitors (TKI) that can be potential therapeutic strategies, although in up to 30% of cases, the underlying mechanism of AR are still unexplained.     

CIP2A mediates erlotinib-induced apoptosis in non-small cell lung cancer cells without EGFR mutation

Background

Epidermal growth factor receptor (EGFR) inhibitors show favorable clinical response in some patients with non-small cell lung cancer (NSCLC) who have no EGFR mutation, indicating alternative mechanisms for their tumoricidal effects. We previously showed erlotinib, a selective EGFR antagonist, inhibited the growth of sensitive hepatocellular carcinoma cells by inhibiting the cancerous inhibitor of protein phosphatase 2A (CIP2A) pathway. The aim of this study was to determine if erlotinib can also inhibit the growth of NSCLC cells by inactivating the CIP2A-dependent signaling pathway.

Methods

Four NSCLC cell lines (H358 H441 H460 and A549) were treated with erlotinib to determine their sensitivity to erlotinib-induced cell death and apoptosis. Expression of CIP2A and the downstream AKT were analyzed. The effects of CIP2A on erlotinib-induced apoptosis were confirmed by overexpression of CIP2A and knockdown of CIP2A gene expression in the sensitive cells and resistant cells, respectively. In vivo efficacy of erlotinib against H358 xenograft tumor was also determined in nude mice.

Results

Erlotinib induced significant cell death and apoptosis in H358 and H441 cells, as evidenced by increased caspase 3 activity and cleavage of pro-caspase 9 and PARP, but not in H460 or A549 cells. The apoptotic effect of erlotinib in the sensitive H358 cells was associated with downregulation of CIP2A, increase in PP2A activity and decrease in AKT phosphorylation. Overexpression of CIP2A and AKT protected the sensitive H358 cells from erlotinib-induced apoptosis. Knockdown of CIP2A gene expression by siRNA enhanced the erlotinib-induced apoptotic in the resistant H460 cells that resembled the sensitive H358 cells. Erlotinib also inhibited the growth of H358 tumors in nude mice.

Conclusions

The CIP2A-dependent pathway mediates the tumoricidal effects of erlotinib on NSCLC cells without EGFR mutations in vitro and in vivo. CIP2A may be a novel molecular target against NSCLC for future drug development.     

CRKL amplification is rare as a mechanism for acquired resistance to kinase inhibitors in lung cancers with epidermal growth factor receptor mutation

Objectives

Epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) often provide dramatic responses in lung cancer patients with somatic EGFR mutation. However, acquired resistance to the drugs usually emerges within a few years. EGFR T790M secondary mutation, MET gene amplification, and transformation to small cell lung cancer are well-validated mechanisms that underlie acquisition of resistance to EGFR-TKIs. In addition, many molecular aberrations have been reported as candidates for mechanisms of acquired resistance to EGFR-TKIs. Amplification of the CRKL gene was reportedly observed in 1 of 11 lung cancer patients with EGFR mutations who acquired resistance to EGFR-TKI. This study is the first report, to our knowledge, that validated the role of CRKL gene amplification as a mechanism for acquisition of resistance to EGFR-TKIs.

Materials and methods

We analyzed CRKL gene copy numbers, using a quantitative real-time PCR method, in 2 in vitro acquired-resistance cell-line models: 11 clinical samples from patients who developed acquired resistance to EGFR-TKIs, and 39 tumor specimens obtained from 7 autopsy patients whose cancers acquired resistance to EGFR-TKIs. Mutational status of EGFR codon 790 and copy numbers for the MET gene were also determined.

Results and conclusion

In analysis for in vitro models, CRKL gene copy numbers were identical between EGFR-TKI-sensitive parental cells and their acquired resistant descendant cells. In addition, we found no clinical tumor specimens with acquired EGFR-TKI resistance to harbor amplified CRKL genes. These results indicate that CRKL gene amplification is rare in acquisition of resistance to EGFR-TKIs in lung cancer patients with EGFR mutations.     

Molecular phenotype predicts sensitivity of squamous cell carcinoma of the head and neck to epidermal growth factor receptor inhibition

Despite nearly universal expression of the wild-type epidermal growth factor receptor (EGFR) and reproducible activity of EGFR inhibitors in patients with squamous cell carcinoma of the head and neck (SCCHN), the majority of patients will not have objective responses. The mechanisms of this intrinsic resistance are not well established. We hypothesized that sensitivity to EGFR inhibitors can be predicted based on the inhibitors' effects on downstream signaling. Cell viability assays were used to assess sensitivity to the EGFR inhibitor gefitinib (ZD1839) in 8 SCCHN cell lines. Fluorescence in-situ hybridization showed the two most sensitive lines to be highly gene-amplified for EGFR. Western blotting confirmed that phosphoEGFR was inhibited at low concentrations of gefitinib in all lines tested. Phosphorylation of downstream signaling protein AKT was inhibited in sensitive lines while inhibition of phosphoERK displayed no relationship to gefitinib efficacy. Phosphatase and tensin homolog (PTEN) expression was evident in all cell lines. Activating PIK3CA mutations were found in two resistant cell lines where pAKT was not inhibited by gefitinib. In resistant cell lines harboring PIK3CA mutations, a PI3K inhibitor, LY294002, or AKT siRNA reduced cell viability with an additive effect demonstrated in combination with gefitinib. Additionally, LY294002 alone and in combination with gefitinib, was effective at treating PIK3CA mutated tumors xenografted into nude mice. Taken together this suggests that constitutively active AKT is a mechanism of intrinsic gefitinib resistance in SCCHN. This resistance can be overcome through targeting of the PI3K/AKT pathway in combination with EGFR inhibition.     

A prospective,phase II,open-label study (JO22903) of first-line erlotinib in Japanese patients with epidermal growth factor receptor (EGFR) mutation-positive advanced non-small-cell lung cancer (NSCLC)

Introduction

The epidermal growth factor receptor (EGFR) tyrosine-kinase inhibitor erlotinib is associated with survival benefits in patients with EGFR mutation-positive non-small-cell lung cancer (NSCLC). This phase II, single-arm study examined the efficacy and safety of first-line erlotinib in Japanese patients with EGFR mutation-positive NSCLC.

Methods

Eligible patients received erlotinib 150 mg/day until disease progression or unacceptable toxicity. The primary endpoints were progression-free survival (PFS) and safety.

Results

A high degree of concordance was observed between different mutation testing methodologies, suggesting feasibility of early, rapid detection of EGFR mutations. Median PFS was 11.8 months (95% confidence interval [CI]: 9.7–15.3) at data cut-off (1 June 2012) (n = 102). Exon 19 deletions seemed to be associated with longer PFS compared with L858R mutations; T790M mutations were tentatively linked with shorter PFS. The safety profile was as expected: rash (any grade; 83%) and diarrhea (any grade; 81%) were most common. Six interstitial lung disease (ILD)-like cases were reported, and 5 were confirmed as ILD-like events by the extramural committee. Two patients died of treatment-related pneumonitis (JAPIC Clinical Trials Information number: Japic CTI-101085).

Conclusion

Erlotinib should be considered for first-line treatment in this subset of Japanese patients, with close monitoring for ILD-like events.     

非小细胞肺癌组织中表皮生长因子受体磷脂酰肌醇3激酶蛋白激酶B1及哺乳动物雷帕霉素靶蛋白mRNA表达及其临床意义

目的探讨磷脂酰肌醇3激酶/蛋白激酶B1/哺乳动物雷帕霉素靶蛋白(PI3K/Akt1/m TOR)通路与表皮生长因子受体(EGFR)基因的关系,及其PI3K/Akt1/m TOR通路导致EGFR-酪氨酸激酶抑制剂(TKI)耐药的具体机制。方法选择135例未经过放化疗或靶向药物治疗的非小细胞肺癌(NSCLC)患者的肿瘤组织标本,检测其EGFR、PIK3CA、Akt1和m TOR的mRNA表达水平,并进行相关性分析。结果 EGFR与Akt1、m TOR的表达水平呈正相关(r分别为0.342、0.320和0.281,均P<0.01),与PIK3CA基因无关。结论 EGFR基因表达与Akt1和m TOR相关,与PIK3CA无关,提示EGFR基因可能直接激活Akt及其下游通路,而不经过PI3K。     

Good response to pemetrexed in patients of lung adenocarcinoma with epidermal growth factor receptor (EGFR) mutations

There are no reports about epidermal growth factor receptor (EGFR) mutations and the responsiveness to pemetrexed treatment. In order to understand the influence of EGFR mutations on pemetrexed response, we performed EGFR sequencing of lung adenocarcinoma from patients undergoing pemetrexed treatment and analyzed their response to pemetrexed. The pemetrexed-treated lung adenocarcinoma patients with adequate specimens for EGFR sequencing and measurable target lesions were enrolled for response analysis. Demographic data, EGFR mutation status, response to pemetrexed, and survival data were collected. From January 2004 to December 2008, 156 patients with measurable target lesions and EGFR sequencing results had complete clinical data for analysis. The patients with EGFR mutations (N = 93) had a better response rate (p = 0.016) and longer progression-free survival (PFS) (p = 0.030) than those with wild type EGFR (N = 63). By multivariate analysis, those who had better performance status (p = 0.013) and EGFR mutations (p = 0.021) had a longer PFS. In conclusion, lung adenocarcinoma patients receiving pemetrexed with EGFR mutations have a better response rate and longer PFS than those with wild type EGFR.     

MLH1 V384D polymorphism associates with poor response to EGFR tyrosine kinase inhibitors in patients with EGFR L858R-positive lung adenocarcinoma

A significant fraction of patients with lung adenocarcinomas harboring activating epidermal growth factor receptor (EGFR) mutations do not experience clinical benefits from EGFR tyrosine kinase inhibitor (TKI) therapy. Using next-generation sequencing, we screened 739 mutation hotspots in 46 cancer-related genes in EGFR L858R-mutant lung adenocarcinomas from 29 patients who received EGFR-TKI therapy; 13 had short (< 3 months) and 16 had long (> 1 year) progression-free survival (PFS). We discovered MLH1 V384D as a genetic variant enriched in the group of patients with short PFS. Next, we investigated this genetic variation in 158 lung adenocarcinomas with the EGFR L858R mutation and found 14 (8.9%) patients had MLH1 V384D; available blood or non-tumor tissues from patients were also tested positive for MLH1 V384D. Patients with MLH1 V384D had a significantly shorter median PFS than those without (5.1 vs. 10.6 months; P= 0.001). Multivariate analysis showed that MLH1 V384D polymorphism was an independent predictor for a reduced PFS time (hazard ratio, 3.5; 95% confidence interval, 1.7 to 7.2; P= 0.001). In conclusion, MLH1 V384D polymorphism is associated with primary resistance to EGFR-TKIs in patients with EGFR L858R-positive lung adenocarcinoma and may potentially be a novel biomarker to guide treatment decisions.     

Ganoderma tsugae extract inhibits expression of epidermal growth factor receptor and angiogenesis in human epidermoid carcinoma cells: In vitro and in vivo

We examined the anti-angiogenic effects of Ganoderma tsugae methanol extract (GTME) on human epidermoid carcinoma A-431 cells. Our data indicate that GTME inhibits the expression of epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) in vitro and in vivo, and also inhibits the capillary tube formation of human umbilical vein endothelial cells (HUVECs). We also show that the suppression of VEGF expression by GTME can be restored by treatment with EGF. These results suggest that GTME inhibits VEGF expression via the suppression of EGFR expression, resulting in the downregulation of VEGF secretion from epidermoid carcinoma A-431 cells. These findings reveal a novel role for G. tsugae in inhibiting EGFR and VEGF expression, which are important for tumor angiogenesis and growth. Thus, GTME may provide a potential therapeutic approach for anti-tumor treatment.     

Detection of EGFR mutations in plasma DNA from lung cancer patients by mass spectrometry genotyping is predictive of tumor EGFR status and response to EGFR inhibitors

Aims

EGFR mutations now guide the clinical use of EGFR-targeted therapy in lung cancer. However, standard EGFR mutation analysis requires a minimum amount of tumor tissue, which may not be available in certain situations. In this study, we combined a mass spectrometry genotyping assay (Sequenom) with a mutant-enriched PCR (ME-PCR) to detect EGFR mutations in free plasma DNA from patients with lung cancer.

Method

DNAs were extracted from 31 plasma samples from 31 patients and analyzed by both methods for EGFR Exon 19 deletion and EGFR L858R mutation. Results in plasma DNA samples were compared with EGFR mutation status obtained in tumor DNA (18/31 EGFR mutant). The relationship of EGFR mutation status in tumor and/or plasma samples to overall survival was assessed.

Results

The EGFR mutation status in plasma DNA was identical to the primary tumor in 61% of patients (19/31). By mass spectrometry genotyping, the plasma samples contained mutant DNA corresponding to 5/14 EGFR Exon 19 deletions and 3/4 EGFR L858R mutations previously diagnosed in the matched tumors. Two samples were positive in plasma DNA but negative in primary tumor tissue. Results were similar for samples studied by ME-PCR. For patients treated with erlotinib, overall survival was correlated with the presence of EGFR mutation in plasma and/or tumor tissue (p = 0.002), with the two patients positive only in plasma DNA showing responses and favorable outcomes.

Conclusion

The detection of EGFR mutations in plasma DNA samples by mass spectrometry genotyping and ME-PCR is feasible. A positive EGFR result in plasma DNA has a high predictive value for tumor EGFR status and for favorable clinical course on EGFR-targeted therapy and could therefore be useful in guiding clinical decisions in patients with insufficient or unavailable tumor specimens.     

The usefulness of mutation-specific antibodies in detecting epidermal growth factor receptor mutations and in predicting response to tyrosine kinase inhibitor therapy in lung adenocarcinoma

Introduction

Among the mutations of epidermal growth factor receptor (EGFR), deletions in exon 19 (DEL), and point mutations in exon 21 (L858R) predict the response to EGFR-tyrosine kinase inhibitors (TKIs) in primary lung adenocarcinoma. The ability to detecting such mutations using immunohistochemistry (IHC) would be advantageous.

Methods

The molecular-based and IHC-based EGFR mutations were analyzed in 577 lung adenocarcinomas using high resolution melting analysis (HRMA) and 2 mutation-specific antibodies, respectively.

Results

In the molecular-based analyses, DEL was detected in 135 cases (23%), and L858R was detected in 172 cases (30%). In the IHC-based analyses, a positive reaction was detected in 59 cases (10%) for the DEL-specific antibody, and in 139 cases (24%) for the L858R-specific antibody. With the molecular-based results set as the gold standard, the sensitivity and specificity of the DEL-specific antibody were 42.2% and 99.5%, respectively, while the sensitivity and specificity of the L858R-specific antibody were 75.6% and 97.8%, respectively. The antibody specificities improved when the threshold for the mutation-positive reactions was set as >50% of immunopositive tumor cells. The significant predictors of the clinical response to EGFR-TKI were molecular-based EGFR mutations (p < 0.001) and IHC-based EGFR mutations (p = 0.001). However, a multivariate analysis revealed that only molecular-based EGFR mutations were significantly correlated with the clinical response (p < 0.001).

Conclusions

Mutation-specific antibodies demonstrated extremely high specificities, but their sensitivities were not higher than those of molecular-based analyses. However, IHC should be performed before a molecular-based analysis, because it is more cost-effective and can effectively select candidates for EGFR-TKI therapy.     

Fibroblast growth factor receptor 1 (FGFR1) copy number is an independent prognostic factor in non-small cell lung cancer

Fibroblast growth factor receptor 1 (FGFR1) is an oncogene that can potentially be targeted by tyrosine kinase inhibitors. We aimed to investigate the prevalence and prognostic significance of alterations in FGFR1 copy number in non-small cell lung cancer (NSCLC). FGFR1 status was evaluated by chromogenic silver in situ hybridisation (ISH) in tissue microarray sections from a retrospective cohort of 304 surgically resected NSCLCs and results were correlated with the clinicopathological features and overall survival. High FGFR1 gene copy number (amplification or high-level polysomy) was significantly more frequent in squamous cell carcinomas (SCC) (24.8%) and large cell carcinomas (LCC) (25%) compared to adenocarcinomas (11.3%) (p = 0.01 and p = 0.03 respectively). Among NSCLC there was no significant correlation between FGFR1-positive status and other clinicopathological features including age, gender, smoking history, tumour size, lymph node status, stage, grade, vascular, lymphatic or perineural invasion. FGFR1-positive patients showed a tendency to longer overall survival in univariate analysis (p = 0.14). Multivariate survival analysis using Cox regression model confirmed FGFR1-positive patients had a significant reduction in the risk of death compared to FGFR1-negative patients (HR 0.6; p = 0.02). High FGFR1 gene copy number is a common finding in SCC and LCC and is an independent favourable prognostic factor.     

First‐line epidermal growth factor receptor (EGFR)–tyrosine kinase inhibitor alone or with whole‐brain radiotherapy for brain metastases in patients with EGFR‐mutated lung adenocarcinoma

We proposed to compare the outcomes of first‐line epidermal growth factor receptor–tyrosine kinase inhibitor (EGFR‐TKI) alone with EGFR‐TKI plus whole‐brain radiotherapy (WBRT) for the treatment of brain metastases (BM) in patients with EGFR‐mutated lung adenocarcinoma. A total of 1665 patients were screened from 2008 to 2014, and 132 were enrolled in our study. Among the 132 patients, 72 (54.5%) harbored a deletion in exon 19, 97 (73.5%) showed multiple intracranial lesions, and 67 (50.8%) had asymptomatic BM. Seventy‐nine patients (59.8%) were treated with EGFR‐TKI alone, 53 with concomitant WBRT. The intracranial objective response rate was significantly higher in the EGFR‐TKI plus WBRT treatment group (67.9%) compared with the EGFR‐TKI alone group (39.2%) (P = 0.001). After a median follow‐up of 36.2 months, 62.1% of patients were still alive. The median intracranial TTP was 24.7 months (95% CI, 19.5–29.9) in patients who received WBRT, which was significantly longer than in those who received EGFR‐TKI alone, with the median intracranial TTP of 18.2 months (95% CI, 12.5–23.9) (P = 0.004). There was no significant difference in overall survival between WBRT and EGFR‐TKI alone groups, (median, 48.0 vs 41.1 months; P = 0.740). The overall survival is significantly prolonged in patients who had an intracranial TTP exceeding 22 months compared to those who developed intracranial progression <22 months after treatment, (median, 58.0 vs 28.0 months; P = 0.001). For EGFR‐mutated lung adenocarcinoma patients with BM, treatment with concomitant WBRT achieved a higher response rate of BM and significant improvement in intracranial progression‐free survival compared with EGFR‐TKI alone.     

Tumor-suppressive microRNA-449a induces growth arrest and senescence by targeting E2F3 in human lung cancer cells

MicroRNA-449a (miR-449a) was significantly downregulated in 156 lung cancer tissues (p < 0.001). We found that the low expression of miR-449a was highly correlated with cancer recurrence and survival of lung cancer patients. The transient introduction of miR-449a caused cell cycle arrest and cell senescence in A549 and 95D cells. Further studies revealed that E2F3 was a direct target of miR-449a in lung cancer cells. miR-449a also suppressed tumor formation in vivo in nude mice. These results suggest that miR-449a plays an important role in lung cancer tumorigenesis and that miR-449a might predict cancer recurrence and survival of lung cancer patients.