A case of endobronchial metastasis of colon cancer mimics sarcoidosis, and a review of related literature.

PURPOSE: Endobronchial metastases (EBM) are defined as bronchoscopically visible lesions histopathologically identical to extrapulmonary tumors. We summarized the literature on endobronchial metastasis of colorectal cancer and give a brief review. METHOD: We present a rare case with an episode mistaken for sarcoidosis and unexpectedly identified as colon cancer by bronchoscopic biopsy. A 53-year-old man with dry cough and dyspnea had diffuse micro lung nodules and lymphadenopathy on CT and PET/CT. He was diagnosed with sarcoidosis and took steroid therapy, but the symptoms could not be alleviated. Bronchoscopy was suggested. He was finally identified with colon cancer by bronchoscopic biopsy, which was confirmed by endoscopic biopsy. We summarise the clinical manifestations, imaging, prognosis of EMB of colorectal cancer. RESULT: EBM are rare. Colorectal cancer is common in EBM and the frequency is increasing. CONCLUSION: EBM should be distinguished from primary lung cancer, sarcoidosis.

MCM5 Aggravates the HDAC1-Mediated Malignant Progression of Lung Cancer.

BACKGROUND: Histone deacetylase 1 (HDAC1) is essential in the malignant progression of tumors. However, there is no obvious relationship between the expression of HDAC1 and the survival of lung cancer patients. Herein, we explored the involvement of minichromosome maintenance complex component 5 (MCM5) and HDAC1 interaction in the epithelial-to-mesenchymal transition (EMT)-dependent malignant progression of lung cancer. METHODS: We analyzed the expression of MCM5 and HDAC1 in The Cancer Genome Atlas database and clinical samples, as well as their impact on patient survival. Cell and animal experiments were performed to verify the promotion of EMT in lung cancer cells mediated by MCM5 and HDAC1. RESULTS: We found that lung adenocarcinoma patients with high expression of MCM5 and HDAC1 had poor survival time. Overexpression of MCM5 and HDAC1 in A549 and H1975 cells can promote proliferation and invasion in vitro and tumor growth and metastasis in vivo. Moreover, astragaloside IV can block the interaction between HDAC1 and MCM5, which can then inhibit the malignant progression of lung cancer in vivo and in vitro. CONCLUSION: The interaction between MCM5 and HDAC1 aggravated the EMT-dependent malignant progression of lung cancer. Astragaloside IV can block the interaction between MCM5 and HDAC1 to inhibit the progression of lung cancer.

Targeting DNA-PK overcomes acquired resistance to third-generation EGFR-TKI osimertinib in non-small-cell lung cancer.

The third-generation of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), represented by osimertinib, has achieved remarkable clinical outcomes in the treatment of non-small-cell lung cancer (NSCLC) with EGFR mutation. However, resistance eventually emerges in most patients and the underlying molecular mechanisms remain to be fully understood. In this study, we generated an osimertinib-acquired resistant lung cancer model from a NSCLC cell line H1975 harboring EGFR L858R and T790M mutations. We found that the capacity of DNA damage repair was compromised in the osimertinib resistant cells, evidenced by increased levels of γH2AX and higher intensity of the comet tail after withdrawal from cisplatin. Pharmacological inhibiting the activity or genetic knockdown the expression of DNA-PK, a key kinase in DNA damage response (DDR), sensitized the resistant cells to osimertinib. Combination of osimertinib with the DNA-PK inhibitor, PI-103, or NU7441, synergistically suppressed the proliferation of the resistant cells. Mechanistically, we revealed that DNA-PK inhibitor in combination with osimertinib resulted in prolonged DNA damage and cell cycle arrest. These findings shed new light on the mechanisms of osimertinib resistance in the aspect of DNA repair, and provide a rationale for targeting DNA-PK as a therapeutic strategy to overcome osimertinib-acquired resistance in NSCLC.

A pooled analysis of molecularly targeted agents for treatment of metastatic oesophago-gastric cancer in elderly patients.

INTRODUCTION: The aim of the present study was to assess the efficacy of molecularly targeted agents (MTAs) in the treatment of elderly patients with metastatic oesophago-gastric cancer (mOGC). MATERIAL AND METHODS: We systematically searched electronic databases and abstracts presented at American Society of Clinical Oncology (ASCO) meetings up to January 31, 2017. Hazard ratios (HRs) were used to estimate overall survival (OS) and progression-free survival (PFS). Subgroup analysis and publication bias were also evaluated. All statistical analysis was conducted using Comprehensive Meta Analysis software (Version 2.0). RESULTS: A total of 2,149 elderly patients with mOGC from thirteen trials were included. Compared to non-MTA-containing regimens, OS was significantly improved in the MTA-containing regimens (HR = 0.86, 95% CI: 0.75-0.99, p = 0.037), but not for PFS (HR = 1.05, 95% CI: 0.85-1.30, p = 0.67). In addition, subgroup analysis indicated that MTA-containing regimens as second-line therapy in elderly mOGC patients significantly improved PFS (HR = 0.58; 95% CI: 0.39-0.85, p = 0.005) and OS (HR = 0.82, 95% CI: 0.70-0.96, p = 0.016), but did not significantly improve PFS (HR = 1.36; 95% CI: 1.06-1.76, p = 0.017) and OS (HR = 0.98, 95% CI: 0.77-1.27, p = 0.90) for MTA-containing regimens as first-line therapy in these patients. No publication bias was detected by Begg's and Egger's tests for OS and PFS. CONCLUSIONS: Our results indicate that the MTA-containing therapies significantly improve OS but not for PFS in elderly mOGC patients. Sub-group analysis shows that improved efficacy is only observed in the second-line setting and not in the first-line setting. Our findings support the use of angiogenesis as second-line treatment for elderly mOGC patients.

Histologic transformation of lung adenocarcinoma to squamous cell carcinoma after chemotherapy: two case reports.

Squamous cell carcinoma (SCC) transformation of lung adenocarcinoma has been reported to take place after target therapy resistance. The patterns and mechanisms underlying this phenomenon needs to be explored. We present two such patients here. One patient complained of cough and hemoptysis, the other experienced chest tightness. Both were diagnosed as lung adenocarcinoma. They harbored no driver gene alterations and received first-line and adjuvant chemotherapy respectively. After progression several months later, the second biopsy revealed SCC transformation and the gene test still found no gene abnormalities. The diseases stayed stable after treatment of new therapeutic regimens. Then we searched for literature related and found SCC transformation happened at resistance to target therapy or immunotherapy or spontaneously. Our cases suggested this phenomenon could also happen at resistance to cytotoxic drugs. According to the reported cases, a new target therapy or chemotherapy might be effective after SCC transformation. The mechanisms underlying transformation have not been fully elucidated and probably relate to multiple genetic alterations and cancer stem cells. Since the SCC transformation could happen under various circumstances, we recommend lung cancer patients to run the second biopsy after progression and conduct gene tests to elicit the mechanisms.

Factors associated with gene aberration test status and treatment decision in patients with unresectable Stage IIIB/IV nonsquamous non-small cell lung cancer: A multicenter survey in China (CTONG 1506).

OBJECTIVES: This study investigated factors associated with (i) the likelihood of receiving a gene aberration test and (ii) the choice of treatment between chemotherapy and targeted therapy in patients with non-small cell lung cancer (NSCLC) in China. MATERIALS AND METHODS: This cross-sectional study analyzed data previously extracted from the medical charts of patients with unresectable Stage IIIB/IV nonsquamous NSCLC discharged from one of 12 tertiary hospitals in China between August 2015 and March 2016. Logistic regressions were applied to investigate factors associated with receiving a gene aberration test and the treatment decision. RESULTS: Data from 932 patients were analyzed. Patients were less likely to have a gene aberration test if they had a histologic subtype other than adenocarcinoma or a hospital waiting time for test results of >5 days. Patients were more likely to receive tyrosine kinase inhibitor (TKI) treatment than chemotherapy if they had a positive result for epidermal growth factor receptor (EGFR)/anaplastic lymphoma kinase gene aberration testing. EGFR positive patients were more likely to receive TKI treatment than chemotherapy if they did not have insurance for TKI or pemetrexed treatment, and more likely to receive chemotherapy than TKI treatment if they had a waiting time for test results of >5 days. EGFR wild-type/unknown patients receiving chemotherapy were more likely to receive pemetrexed if they attended a hospital in a developed area or had insurance for pemetrexed. CONCLUSION: In this real-world setting in China, the choice of first-line treatment for advanced NSCLC was appropriately guided by gene aberration testing for most patients. However, gene aberration testing and the treatment decision were influenced by practical factors such as hospital location, the waiting time for test results, and insurance coverage, which should be addressed to ensure optimal patient care.

EGFR-TKI resistance and MAP17 are associated with cancer stem cell like properties.

Patients with non-small-cell lung cancer (NSCLC) with sensitive epidermal growth factor receptor (EGFR) mutations generally react well to tyrosine kinase inhibitors (TKIs). However acquired resistance eventually occurs. Several mechanisms contribute to the resistance including T790M mutation, c-Met amplification and PIK3CA mutation. In recent years, cancer stem cells (CSCs) have been suggested to be involved in TKI resistance. MAP17 is aberrantly overexpressed in a number of malignancies. However, the expression pattern and function of MAP17 in CSCs are still unclear. The aim the present study was to illustrate the effect of CSC-like cells on the resistance to TKIs in EGFR mutant NSCLC cells and explore the possible role of MAP17 in CSCs. The EGFR mutant cell line PC9 was cultured under serum-deprived undifferentiated conditions. The CSC properties including expression of stem cell markers CD133, CD44, Oct-4 and ABCG2, ability of self-renewal, invasion, proliferation and tumorigenesis were examined. The expression of MAP17 was compared in sphere and parent cells. Sphere cells displayed stem cells phenotypes and were resistant to erlotinib. Sphere cells expressed higher levels of MAP17, and MAP17 was associated with self-renewal and TKI resistance. The function of MAP17 demonstrated to be partially dependent on Na-dependent glucose transporter 1. Collectively these findings suggest that MAP17 serves a role in TKI resistance through regulation of CSCs in lung cancer.

Histological transformation after acquired resistance to epidermal growth factor tyrosine kinase inhibitors.

Non-small-cell lung cancer patients with sensitive epidermal growth factor receptor mutations generally respond well to tyrosine kinase inhibitors (TKIs). However, acquired resistance will eventually develop place after 8-16 months. Several mechanisms contribute to the resistance including T790M mutation, c-Met amplification, epithelial mesenchymal transformation and PIK3CA mutation; however, histological transformation is a rare mechanism. The patterns and mechanisms underlying histological transformation need to be explored. We searched PubMed, EMBASE and search engines Google Scholar, Medical Matrix for literature related to histological transformation. Case reports, cases series, and clinical and basic medical research articles were reviewed. Sixty-one articles were included in this review. Cases of transformation to small-cell lung cancer, squamous cell carcinoma, large-cell neuroendocrine carcinoma and sarcoma after TKI resistance have all been reported. As the clinical course differed dramatically between cases, a new treatment scheme needs to be recruited. The mechanisms underlying histological transformation have not been fully elucidated and probably relate to cancer stem cells, driver genetic alterations under selective pressure or the heterogeneity of the tumor. When TKI resistance develops, we recommend that patients undergo a second biopsy to determine the reason, guide the next treatment and predict the prognosis.

A multicenter survey of first-line treatment patterns and gene aberration test status of patients with unresectable Stage IIIB/IV nonsquamous non-small cell lung cancer in China (CTONG 1506).

BACKGROUND: In recent years, systemic chemotherapy and molecular targeted therapy have become standard first-line treatments for locally advanced or metastatic nonsquamous non-small cell lung cancer (NSCLC). The objective of this survey was to investigate first-line anticancer treatment patterns and gene aberration test status of patients with advanced nonsquamous NSCLC in China. METHODS: Patients included in this study had unresectable Stage IIIB/IV nonsquamous NSCLC and were admitted during August 2015 to March 2016 into one of 12 tertiary hospitals throughout China for first-line anticancer treatment. Patient data (demographics, NSCLC histologic type, Eastern Cooperative Oncology Group [ECOG] Performance Status [PS], gene aberration test and results [if performed], and first-line anticancer treatment regimen) were extracted from medical charts and entered into Medical Record Abstraction Forms (MERAFs), which were collated for analysis. RESULTS: Overall, 1041 MERAFs were collected and data from 932 MERAFs were included for analysis. Patients with unresectable Stage IIIB/IV nonsquamous NSCLC had a median age of 59 years, 56.4% were male, 58.2% were never smokers, 95.0% had adenocarcinoma, and 92.9% had an ECOG PS ≤1. A total of 665 (71.4%) patients had gene aberration tests; 46.5% (309/665) had epidermal growth factor receptor (EGFR) gene mutations, 11.5% (48/416) had anaplastic lymphoma kinase (ALK) gene fusions, and 0.8% (1/128) had a c-ros oncogene 1 gene fusion. The most common first-line treatment regimen for unresectable Stage IIIB/IV nonsquamous NSCLC was chemotherapy (72.5%, 676/932), followed by tyrosine kinase inhibitors (TKIs; 26.1%, 243/932), and TKIs plus chemotherapy (1.4%, 13/932). Most chemotherapy regimens were platinum-doublet regimens (93.5%, 631/676) and pemetrexed was the most common nonplatinum chemotherapy-backbone agent (70.2%, 443/631) in platinum-doublet regimens. Most EGFR mutation-positive patients (66.3%, 205/309) were treated with EGFR-TKIs. CONCLUSIONS: Findings from our survey of 12 tertiary hospitals throughout China showed an increased rate of gene aberration testing, compared with those rates reported in previous surveys, for patients with advanced nonsquamous NSCLC. In addition, pemetrexed/platinum-doublet chemotherapy was the predominant first-line chemotherapy regimen for this population. Most patients were treated based on their gene aberration test status and results.

Different schedules of irinotecan administration: A meta-analysis.

The concept of the UDP glucuronosyltransferase family 1 member A1 genotype-directed schedule of irinotecan administration is still far from being introduced into clinical practice, and the efficacy and toxicity of irinotecan are in part schedule-dependent. The objective of the present meta-analysis was to determine the efficacy and adverse effects of 3-weekly vs. weekly irinotecan for the treatment of solid tumors. The PubMed, EMBASE and Cochrane Library databases and the search engines Google Scholar and Medical Martix were searched for randomized controlled trials to compare the two regimens of irinotecan administration. The results of the meta-analysis indicated that the 3-weekly regimen yielded a longer time to progression, while other measures of efficacy, such as the objective response rate and overall survival of patients with solid tumors were similar between the two regimens of irinotecan administration. Furthermore, the group receiving the 3-weekly regimen had a lower incidence of grade 3/4 diarrhea and a higher rate of grade 3/4 neutropenia compared with the group receiving the weekly regimen. However, these results require confirmation by large-sample, multicenter, randomized, controlled trials.

Increased risk of severe infections in cancer patients treated with vascular endothelial growth factor receptor tyrosine kinase inhibitors: a meta-analysis.

BACKGROUND: Vascular endothelial growth factor receptor tyrosine kinase inhibitors (VEGFR-TKIs) have been widely used in a variety of solid malignancies. Concerns have arisen regarding the risk of severe infections (≥grade 3) with use of these drugs, but the contribution of VEGFR-TKIs to infections is still unknown. METHODS: The databases of PubMed and abstracts presented at oncology conferences' proceedings were searched for relevant studies from January 2000 to December 2014. Summary incidences, Peto odds ratio (Peto OR), and 95% confidence intervals (CIs) were calculated by using either random-effects or fixed-effects models according to the heterogeneity of included studies. RESULTS: A total of 16,488 patients from 27 randomized controlled trials were included. The risk of developing severe (Peto OR 1.69, 95% CI: 1.45-1.96, P<0.001) and fatal infections (Peto OR 1.78, 95% CI: 1.13-2.81, P=0.013) was significantly increased in patients treated with VEGFR-TKIs when compared to controls. Exploratory subgroup analysis showed no effect of tumor types, phase of trials, or agent used on the Peto OR of severe infections. When stratified according to specific infectious events, the risks of high-grade febrile neutropenia, pneumonia, fever, and sepsis were increased compared with controls, with Peto ORs of 1.57 (95% CI: 1.30-1.88, P<0.001), 1.79 (95% CI: 1.29-2.49, P<0.001), 5.35 (95% CI: 1.47-19.51, P=0.011), and 3.68 (95% CI: 1.51-8.99, P=0.004), respectively. Additionally, VEGFR-TKIs significantly increased the risk of fatal sepsis (OR 3.66, 95% CI: 1.47-9.13, P=0.005) but not fatal pneumonia (OR 1.34, 95% CI: 0.80-2.25, P=0.26). CONCLUSION: The use of VEGFR-TKIs significantly increases the risk of developing severe and fatal infectious events in cancer patients. A close monitoring for any signs of infections is recommended for patients treated with VEGFR-TKIs.

The Efficacy and Safety of Chemotherapy in Patients With Nonsmall Cell Lung Cancer and Interstitial Lung Disease: A PRISMA-Compliant Bayesian Meta-Analysis and Systematic Review.

Chemotherapy plays a critical and venturous role against the co-morbidity of nonsmall cell lung cancer and interstitial lung disease (NSCLC-ILD).We performed a Bayesian meta-analysis and systematic review to evaluate the safety and efficacy of the chemotherapy in NSCLC-ILD patients.EMBASE, PubMed, the Cochrane Central Register of Controlled Trials, and clinicaltrials.gov (up to January 2015).We included all study designs except case reports, all studies with NSCLC-ILD patients and all the possible chemotherapy regimens.Quality was assessed by a components approach. We derived summary estimates using Bayesian method through WinBUGS (version 1.4.3, MRC Biostatistics Unit, Cambridge, UK).Seven studies involving 251 patients with NSCLC-ILD were included in the meta-analysis. The treatment response (complete remission, 0; [partial remission, 39.1%; 95% credible interval [CrI], 32.6-45.7]; [stable disease, 36%; 95% CrI, 29.6-42.2]; [PD, 15.4%; 95% CrI, 11.3-19.8]; [nonevaluable, 6.4%; 95% CrI, 2.7-10.1]; [overall response rate, 41.3%; 95% CrI, 35.3-47.4]; [disease control rate, 77.7%; 95% CrI, 72.2-82.7]) were comparable to that of patients with NSCLC alone; the survival outcomes (median overall survival, median progression-free survival, and 1-year survival rate) were slightly worse, especially the lower 1-year survival rate. Platinum-based doublets as first-line chemotherapy may be related to higher incidence of acute exacerbation-ILD in first line chemotherapy (AE, 8.47%; 95% CrI, 5.04-12.6).The data selection bias and small patient number make the meta-analysis of treatment response and conclusions generated from these data inaccurate.The present meta-analysis suggests that chemotherapy might be an effective therapy for patients with NSCLC-ILD, but it might be associated with higher incidence of acute exacerbation.

LKB1 gene inactivation does not sensitize non-small cell lung cancer cells to mTOR inhibitors in vitro.

AIM: Previous study has shown that endometrial cancers with LKB1 inactivation are highly responsive to mTOR inhibitors. In this study we examined the effect of LKB1 gene status on mTOR inhibitor responses in non-small cell lung cancer (NSCLC) cells. METHODS: Lung cancer cell lines Calu-1, H460, H1299, H1792, and A549 were treated with the mTOR inhibitors rapamycin or everolimus (RAD001). The mTOR activity was evaluated by measuring the phosphorylation of 4EBP1 and S6K, the two primary mTOR substrates. Cells proliferation was measured by MTS or sulforhodamine B assays. RESULTS: The basal level of mTOR activity in LKB1 mutant A549 and H460 cells was significantly higher than that in LKB1 wild-type Calu-1 and H1792 cells. However, the LKB1 mutant A549 and H460 cells were not more sensitive to the mTOR inhibitors than the LKB1 wild-type Calu-1 and H1792 cells. Moreover, knockdown of LKB1 gene in H1299 cells did not increase the sensitivity to the mTOR inhibitors. Treatment with rapamycin or RAD001 significantly increased the phosphorylation of AKT in both LKB1 wild-type and LKB1 mutant NSCLC cells, which was attenuated by the PI3K inhibitor LY294002. Furthermore, RAD001 combined with LY294002 markedly enhanced the growth inhibition on LKB1 wild-type H1792 cells and LKB1 mutant A549 cells. CONCLUSION: LKB1 gene inactivation in NSCLC cells does not increase the sensitivity to the mTOR inhibitors. The negative feedback activation of AKT by mTOR inhibition may contribute to the resistance of NSCLC cells to mTOR inhibitors.

Overexpression of SAMD9 suppresses tumorigenesis and progression during non small cell lung cancer.

The Sterile Alpha Motif Domain-containing 9 (SAMD9) gene has been recently emphasized during the discovery that it is expressed at a lower level in aggressive fibromatosis and some cases of breast and colon cancer, however, the underlying mechanisms are poorly understood. Here, we found that SAMD9 is down-regulated in human non-small cell lung cancer (NSCLC). Furthermore, knockdown of SAMD9 expression is increased the invasion, migration and proliferation in H1299 cells in vitro and overexpression of SAMD9 suppressed proliferation and invasion in A549 cells. Finally, depletion of SAMD9 increases tumor formation in vivo. Our results may provide a strategy for blocking NSCLC tumorigenesis and progression.

Fast-track surgery for gastroenteric neoplasms: a meta-analysis.

AIMS AND BACKGROUND: Fast-track surgery has been shown to enhance postoperative recovery. The objective of the study was to determine the differences of fast-track surgery and conventional care for patients with gastroenteric neoplasms. METHODS AND STUDY DESIGN: We searched PubMed, EMBASE, and the Cochrane Library for related trials to compare hospital stay and rates of complications and readmission. RESULTS: Thirteen randomized controlled trials, with 1,962 patients, were included. Results showed the length of hospital stay was significantly reduced in the fast-track group. The complications rate was lowered in colorectal surgery. There were no significant differences in rate of readmissions. CONCLUSIONS: Current trials show that fast-track surgery may reduce the length of hospital stay and lower the rate of complications of gastroenteric surgery.

Intermittent pneumatic compression pump for breast cancer-related lymphedema: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Breast cancer-related lymphedema (BCRL) is a common complication after the treatment of breast cancer. The objective of this study was to determine whether the use of an intermittent pneumatic pump (IPC) could manage lymphedema effectively. METHODS: We searched PubMed, EMBASE, and the Cochrane Library for related trials to compare the percent of volume reduction and subjective symptoms. RESULTS: 7 randomized controlled trials, with 287 patients, were included. Results showed that the use of the IPC could alleviate lymphedema, but no significant difference between routine management of lymphedema with or without pneumatic pump existed. CONCLUSION: Current trials fail to show the effectiveness of the addition of an IPC to the routine management of BCRL.

Erlotinib in a patient with vaginal carcinoma and pulmonary metastasis: A case report.

Erlotinib is an epidermal growth factor receptor tyrosine kinase inhibitor. It is widely used in the treatment of advanced non-small cell lung cancer and pancreatic cancer. However, there are currently no reports of the efficacy of erlotinib in patients with metastatic vaginal carcinoma. A 48-year-old female with vaginal carcinoma was diagnosed with lung metastasis four years following surgery. The patient received three cycles of chemotherapy but could not tolerate further treatment due to the side effects. Next, erlotinib was administered, prompting a partial response and disease stabilization for 9 months prior to disease progression. While the main treatments for vaginal carcinoma with distant metastasis are chemotherapy and radiotherapy, this case supplies preliminary evidence that erlotinib may have activity in these patients. Further studies are required to determine the potential of this therapy.

Negative regulation of mTOR activity by LKB1-AMPK signaling in non-small cell lung cancer cells.

AIM: To investigate the role of LKB1 in regulation of mTOR signaling in non-small cell lung cancer (NSCLC) cells. METHODS: LKB1 protein expression and phosphorylation of AMPK, 4E-BP1 and S6K in the cells were assessed using Western blotting in various NSCLC cell lines (A549, H460, H1792, Calu-1 and H1299). Energy stress was mimicked by treating the cells with 2-deoxyglucose (2-DG). Compound C was used to inhibit AMPK activity. Cell growth was measured using the MTS assay. RESULTS: LKB1 protein was expressed in LKB1 wild-type Calu-1, H1299 and H1792 cells, but it was undetected in LKB1 mutant A549 and H460 cells. Treatment of the LKB1 wild-type cells with 2-DG (5, 10 and 25 mmol/L) augmented the phosphorylation of AMPK in dose- and time-dependent manners. In the LKB1 wild-type cells, 2-DG dramatically suppressed the phosphorylation of two mTOR targets, 4E-BP1 and S6K, whereas the LKB1 mutant A549 and H460 cells were highly resistant to 2-DG-induced inhibition on mTOR activity. In addition, stable knockdown of LKB1 in H1299 cells impaired 2-DG-induced inhibition on mTOR activity. Pretreatment of H1299 and H1792 cells with the AMPK inhibitor compound C (10 µmol/L) blocked 2-DG-induced inhibition on mTOR activity. 2-DG inhibited the growth of H1299 cells more effectively than that of H460 cells; stable knockdown of LKB1 in H1299 cells attenuated the growth inhibition caused by 2-DG. CONCLUSION: In non-small cell lung cancer cells, LKB1/AMPK signaling negatively regulates mTOR activity and contributes to cell growth inhibition in response to energy stress.

Molecular mechanisms of LKB1 induced cell cycle arrest.

LKB1 is a serine/threonine protein kinase mutated in patients with Peutz-Jeghers syndrome. Biallelic inactivation of LKB1 is present in up to 30% of cases of non-small cell lung cancer (NSCLC). As a tumor suppressor, LKB1 functions in arresting the cell cycle and inhibiting cell growth. LKB1 leads to induction of p21/WAF1 expression in a p53-dependent mechanism, which is mediated by cytoplasmic LKB1 initiating negative regulation of cell growth or nuclear LKB1 directly involved in transcriptional regulation of p21/WAF1. Alternatively, p53 and p21/WAF1-independent mechanism of regulating cell cycle by LKB1 is also reported.

Establishment and gene expression profiling of LKB1 stable knockdown lung cancer cell line.

BACKGROUND: Lung cancer is the leading cause of cancer-related death in China. Mutation analysis reveals that LKB1 inactivation is present in 30% of non-small-cell lung cancer (NSCLC), indicating its role as a tumor suppressor. However, the molecular mechanism is still not clear. Our study attempted to establish LKB1 stable knockdown NSCLC cell line, detect alterations in gene expression and identify the genes regulated by LKB1. METHODS: LKB1 stable knockdown H1299 cell line was established using a lentiviral short hairpin RNA. To identify the knockdown effect, LKB1 mRNA and protein expression level were evaluated with quantitative real-time PCR and Western blotting. We treated the cell lines with 2-deoxyglucose to determine if LKB1 protein function was impacted. Gene microarray analysis was performed to detect the gene expression alterations in LKB1 stable knockdown H1299 cells. RESULTS: LKB1 mRNA and protein expression were significantly suppressed in LKB1 stable knockdown H1299 cell line. 2-DG treatment had little impact on the phosphorylation of AMPK, which is the downstream target of LKB1, indicating the loss of function of LKB1. The microarray data showed that LKB1 knockdown resulted in expression alterations of 1243 kinds of genes, including those involved in cell migration, cell proliferation and cell apoptosis. CONCLUSIONS: The establishment of LKB1 stable knockdown H1299 cell line provides us with a great tool to investigate various genes regulated by LKB1 through microarray. The discovery of cell proliferation and migration-related genes regulated by LKB1 is critical for unraveling molecular mechanisms of LKB1's role in the development and metastasis of lung cancer.