Multiplatform-based molecular subtypes of non-small-cell lung cancer.

Non-small-cell lung cancer (NSCLC) demonstrates remarkable molecular diversity. With the completion of The Cancer Genome Atlas (TCGA), there is opportunity for systematic analyses of the entire TCGA NSCLC cohort, including comparisons and contrasts between different disease subsets. On the basis of multidimensional and comprehensive molecular characterization (including DNA methylation and copy, and RNA and protein expression), 1023 NSCLC cases-519 from TCGA adenocarcinoma (AD) project and 504 from TCGA squamous cell carcinoma (SQCC) project-were classified using a 'cluster-of-clusters' analytic approach. Patterns from TCGA NSCLC subsets were examined in independent external databases, including the PROSPECT (Profiling of Resistance patterns and Oncogenic Signaling Pathways in Evaluation of Cancers of the Thorax) NSCLC data set. Nine genomic subtypes of NSCLC were identified, three within SQCC and six within AD. SQCC subtypes were associated with transcriptional targets of SOX2 or p63. One predominately AD subtype (with a large proportion of SQCC) shared molecular features with neuroendocrine tumors. Two AD subtypes manifested a CpG island methylator phenotype. Three AD subtypes showed high p38 and mTOR pathway activation. AD subtypes associated with low differentiation showed relatively worse prognosis. SQCC subtypes and two of the AD subtypes expressed cancer testis antigen genes, whereas three AD subtypes expressed several immune checkpoint genes including PDL1 and PDL2, corresponding with patterns of greater immune cell infiltration. Subtype associations for several immune-related markers-including PD1, PDL1, CD3 and CD8-were confirmed in the PROSPECT cohort using immunohistochemistry. NSCLC molecular subtypes have therapeutic implications and lend support to a personalized approach to NSCLC management based on molecular characterization.

Epidermal growth factor receptor regulates MET levels and invasiveness through hypoxia-inducible factor-1alpha in non-small cell lung cancer cells.

Recent studies have established that amplification of the MET proto-oncogene can cause resistance to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC) cell lines with EGFR-activating mutations. The role of non-amplified MET in EGFR-dependent signaling before TKI resistance, however, is not well understood. Using NSCLC cell lines and transgenic models, we demonstrate here that EGFR activation by either mutation or ligand binding increases MET gene expression and protein levels. Our analysis of 202 NSCLC patient specimens was consistent with these observations: levels of MET were significantly higher in NSCLC with EGFR mutations than in NSCLC with wild-type EGFR. EGFR regulation of MET levels in cell lines occurred through the hypoxia-inducible factor (HIF)-1alpha pathway in a hypoxia-independent manner. This regulation was lost, however, after MET gene amplification or overexpression of a constitutively active form of HIF-1alpha. EGFR- and hypoxia-induced invasiveness of NSCLC cells, but not cell survival, were found to be MET dependent. These findings establish that, absent MET amplification, EGFR signaling can regulate MET levels through HIF-1alpha and that MET is a key downstream mediator of EGFR-induced invasiveness in EGFR-dependent NSCLC cells.

A genetic mouse model for metastatic lung cancer with gender differences in survival.

Lung cancer is a devastating disease with poor prognosis. The design of better therapies for lung cancer patients would be greatly aided by good mouse models that closely resemble the human disease. Unfortunately, current models for lung adenocarcinoma are inadequate due to the absence of metastases. In this study, we incorporated both K-ras and p53 missense mutations into the mouse genome and established a more faithful genetic model for human lung adenocarcinoma, the most common type of lung cancer. Mice with both mutations developed advanced lung adenocarcinomas that were highly aggressive and metastasized to multiple intrathoracic and extrathoracic sites in a pattern similar to that of human lung cancer. These mice also showed a gender difference in cancer-related death. Additionally, the presence of both mutations induced pleural mesotheliomas in 23% of these mice. This mouse model recapitulates the metastatic nature of human lung cancer and will be invaluable to further probe the molecular basis of metastatic lung cancer and for translational studies.

c-Jun N-terminal kinase is activated in non-small-cell lung cancer and promotes neoplastic transformation in human bronchial epithelial cells.

c-Jun N-terminal kinase (JNK) has been reported to either potentiate or inhibit oncogenesis, depending upon the cellular context, but its role in lung neoplasia is unclear. Here we sought to define the role of JNK in lung neoplasia by examining evidence of JNK phosphorylation in non-small-cell lung cancer (NSCLC) biopsy samples and by using genetic and pharmacologic approaches to modulate JNK expression and activity in cultured cells. Immunohistochemical staining for JNK phosphorylation was detected in 114 (45%) of 252 NSCLC biopsy samples and was predominantly nuclear, providing evidence of JNK activation in a subset of NSCLC cases. Introduction of a doxycycline-inducible, constitutively active, mutant mitogen-activated protein kinase kinase 4 (MKK4) into the human bronchial epithelial cell lines BEAS-2B and HB56B increased the cells' proliferation, migration, invasion and clonogenicity. Depletion of JNK in MKK4 mutant-transformed BEAS-2B cells by introduction of JNK1/2 short hairpin RNA reversed the transformed phenotype, indicating that JNK activation is oncogenic and MKK4 confers neoplastic properties in these cells. The proliferation of NSCLC cell lines HCC827 and H2009, in which JNK and its substrate c-Jun are constitutively phosphorylated, was inhibited by SP600125, a JNK kinase inhibitor. We conclude that JNK is activated in a subset of NSCLC biopsy samples and promotes oncogenesis in the bronchial epithelium, suggesting that strategies to inhibit the JNK pathway should be considered for the prevention and treatment of NSCLC.

Effects of N-(4-hydroxyphenyl)retinamide on hTERT expression in the bronchial epithelium of cigarette smokers.

BACKGROUND: Telomerase activation plays a critical role in tumorigenesis. To determine the role of telomerase in early lung carcinogenesis and as a potential biomarker in chemoprevention trials, we analyzed the expression of the human telomerase reverse transcriptase catalytic subunit (hTERT) in bronchial biopsy specimens from cigarette smokers who were enrolled in a randomized, double-blinded, placebo-controlled chemoprevention trial of N-(4-hydroxyphenyl)retinamide (4-HPR). METHODS: We obtained biopsy specimens from six predetermined sites in the bronchial tree from the 57 participants, before treatment and 6 months after treatment with 4-HPR or placebo. We used in situ hybridization to examine hTERT messenger RNA (mRNA) expression in 266 pretreatment (baseline) and post-treatment site-paired biopsy specimens from 27 patients in the 4-HPR-treated group and from 30 patients in the placebo-treated group. All statistical tests were two-sided. RESULTS: At baseline, 62.4% (95% confidence interval [CI] = 53.9% to 71%) of the biopsy specimens obtained from the group treated with 4-HPR and 65.2% (95% CI = 57.4% to 73.1%) of the biopsy specimens obtained from the placebo-treated group expressed hTERT mRNA. After 6 months, 45.6% (95% CI = 36.9% to 54.3%) of the biopsy specimens obtained from the 4-HPR-treated group and 68.1% (95% CI = 60.4% to 75.8%) of the biopsy specimens obtained from the placebo-treated group expressed hTERT mRNA. The reduction in hTERT expression observed between the two treatment groups over time was statistically significant (P =.01) when we used the biopsy site as the unit of analysis, but not when we used the individual as the unit of analysis (P =.37). CONCLUSIONS: Telomerase is frequently reactivated in the lungs of cigarette smokers. The modulation of hTERT expression in 4-HPR-treated smokers suggests that a novel molecular mechanism underlies the potential chemopreventive properties of 4-HPR. hTERT expression is a promising potential biomarker for risk assessment and for the evaluation of the efficacy of chemopreventive agents in lung carcinogenesis.

Long-term impact of smoking on lung epithelial proliferation in current and former smokers.

BACKGROUND: Lung cancer risk remains elevated for many years after quitting smoking. To assess using proliferation indices in bronchial tissues as an intermediate endpoint biomarker in lung cancer chemoprevention trials, we determined the relationship between the extent, intensity, and cessation of tobacco smoking and proliferative changes in bronchial epithelial biopsy specimens. METHODS: Bronchial biopsy specimens were obtained from up to six epithelial sites in 120 current smokers (median pack-years, 42) and 207 former smokers (median pack-years, 40; median quit-years, 8.1). Sections from the paraffin-embedded specimens were stained with hematoxylin--eosin to determine the metaplasia index and with an antibody to Ki-67 to determine the proliferative (labeling) index for the basal and parabasal (Ki-67 PLI) layers. All statistical tests were two-sided. RESULTS: Biopsy sites with metaplasia had statistically significantly higher Ki-67-labeling indices than those without metaplasia (P<.001) in both current and former smokers. Increased proliferation was observed in multiple biopsy sites, with the average Ki-67 PLI of the subject strongly correlating with the metaplasia index (r =.72 for current smokers; P<.001), even in sites without metaplasia (r =.23 for current smokers; P<.001). In current smokers, the Ki-67 PLI was associated with the number of packs smoked/day (P =.02) but not with smoking years or pack-years. In subjects who had quit smoking, the Ki-67 PLI dropped statistically significantly within 1 year (P =.008) but remained detectable for more than 20 years, even in the absence of squamous metaplasia. CONCLUSION: Smoking appears to elicit a dose-related proliferative response in the bronchial epithelia of active smokers. Although the proliferative response decreased gradually in former smokers, a subset of individuals had detectable proliferation for many years and may benefit from targeted chemoprevention. Bronchial epithelial proliferation, measured by Ki-67, may provide a useful biomarker in the assessment of lung cancer risk and in the response to chemopreventive interventions.

Insulin-like growth factor binding protein-6 inhibits the growth of human bronchial epithelial cells and increases in abundance with all-trans-retinoic acid treatment.

Retinoids are potent inhibitors of human bronchial epithelial (HBE) cell growth. Retinoids initiate signaling through activation of nuclear receptors, but the signal transduction pathways that mediate growth inhibition have not been defined. In this study, we investigated the expression of insulin-like growth factor (IGF)-binding protein (IGFBP)-6 as a potential mediator of retinoid actions. IGFBP-6 is a secreted glycoprotein that inhibits the bioavailability of IGFs, which are potent mitogens of HBE cells. IGFBP-6 was detected by immunohistochemical staining in the basal epithelial layer of human bronchial organ cultures, and all-trans-retinoic acid (t-RA) treatment increased the intensity of IGFBP-6 immunostaining. In primary cultures of HBE cells treated with t-RA, IGFBP-6 messenger RNA and protein levels increased within 6 and 24 h, respectively, and IGFBP-6 was detected in the conditioned media at 48 h. The effect of IGFBP-6 on HBE cell growth was investigated with a recombinant adenoviral vector, Ad5CMV-BP6, which expresses IGFBP-6 under the control of a cytomegalovirus promoter. IGFBP-6 overexpression induced a proliferative arrest of HBE cells with no evidence of apoptosis. These findings provide the first evidence that IGFBP-6 is expressed in the bronchial epithelium and that IGFBP-6 may contribute to the biologic effects of retinoids on HBE cells.

Insulin-like growth factor binding protein-6 activates programmed cell death in non-small cell lung cancer cells.

Insulin-like growth factor binding proteins (IGFBPs) are secreted into the extra-cellular matrix and inhibit cell growth through IGF-dependent and -independent mechanisms. In this study, we investigated the role of IGFBP-6, a relatively unexplored member of the IGFBP family, in the proliferation of non-small cell lung cancer (NSCLC) cells. Infection of NSCLC cell lines in vitro with an adenovirus expressing human IGFBP-6 under the control of a CMV promoter (Ad5CMV-BP6) reduced NSCLC cell number through activation of programmed cell death, as shown by cell staining with Hoechst 33342 or DNA end-labeling with bromodeoxyuridine triphosphate. The growth regulatory effect of IGFBP-6 was investigated in vivo by intratumoral injection of Ad5CMV-BP6 in NSCLC xenografts established in nu/nu mice. A single injection of Ad5CMV-BP6 reduced the size of NSCLC xenografts by 45%. These findings indicate that IGFBP-6 is a potent inducer of programmed cell death in cancer cells and support investigations into IGFBP-6 as a potential target in cancer therapeutics.

Stress pathway activation induces phosphorylation of retinoid X receptor.

Cellular stresses inhibit retinoid signaling, but the molecular basis for this phenomenon has not been revealed. Here, we present evidence that retinoid X receptor (RXR) is a substrate for both mitogen-activated protein kinase kinase-4 (MKK4/SEK1) and its downstream mediator c-Jun N-terminal kinase (JNK). MKK4/SEK1 and JNK recognized distinct features on RXR in the DE and AB regions, respectively. Phosphorylation by MKK4/SEK1 had profound effects on the biochemical properties of RXR, inhibiting the expression of genes activated by RXR-retinoic acid receptor complexes. Tyr-249 in the RXR DE region was required for the inhibitory effect of MKK4/SEK1. These effects were significantly reduced in MKK4/SEK1-null cells, indicating that MKK4/SEK1 is required for the suppression of retinoid signaling by stress. Findings presented here demonstrate that MKK4/SEK1 can directly modulate transcription by phosphorylating RXR, a novel MKK4/SEK1 substrate.

N-(4-hydroxyphenyl)retinamide in the chemoprevention of squamous metaplasia and dysplasia of the bronchial epithelium.

Lung cancer remains the number one cause of cancer-related deaths in the United States. To reduce the mortality associated with this disease, individuals at risk must be identified prior to the development of lung cancer, and effective prevention strategies must be developed. One such strategy is to use retinoids like N-(4-hydroxyphenyl)retinamide (4-HPR), which has been found to possess chemopreventive activities in preclinical studies. In this study, 139 smokers were registered and 82 were randomized onto a double-blinded, placebo-controlled chemoprevention trial of 4-HPR administered p.o. (200 mg once daily). Of these, 70 participants were eligible for response evaluation. Biopsies were obtained at six predetermined sites in the bronchial tree from participants before and at the completion of 6 months of treatment. 4-HPR treatment had no measurable effect on histopathology (squamous metaplasia and dysplasia) in the bronchial epithelium of current smokers. 4-HPR was detected (104.5+/-64.0 ng/ml, mean +/- SD) in the serum of participants, supporting its potential bioavailability. Serum retinol levels decreased markedly (44% of placebo-treated patients) as a consequence of 4-HPR treatment. Notably, the mRNA level of retinoic acid receptor beta, which is typically increased by retinoid treatment, did not change in the bronchial epithelium of 4-HPR-treated participants. Clonal populations of bronchial epithelial cells were detected by analysis of loss of heterozygosity at putative tumor suppressor loci on chromosomes 3p, 9p, and 17p, and these changes were not altered by 4-HPR treatment. In conclusion, at this dose and schedule, 4-HPR was not effective in reversing squamous metaplasia, dysplasia, or genetic and phenotypic abnormalities in the bronchial epithelium of smokers.

Direct functional interactions between insulin-like growth factor-binding protein-3 and retinoid X receptor-alpha regulate transcriptional signaling and apoptosis.

Insulin-like growth factor-binding protein (IGFBP)-3 regulates apoptosis in an IGF-independent fashion and has been shown to localize to nuclei. We cloned the nuclear receptor retinoid X receptor-alpha(RXR-alpha) as an IGFBP-3 protein partner in a yeast two-hybrid screen. Multiple methodologies showed that IGFBP-3 and RXR-alpha bind each other within the nucleus. IGFBP-3-induced apoptosis was abolished in RXR-alpha-knockout cells. IGFBP-3 and RXR ligands were additive in inducing apoptosis in prostate cancer cells. IGFBP-3 enhanced RXR response element and inhibited RARE signaling. Thus, RXR-alpha-IGFBP-3 interaction leads to modulation of the transcriptional activity of RXR-alpha and is essential for mediating the effects of IGFBP-3 on apoptosis.

Cellular and humoral immune responses to adenovirus and p53 protein antigens in patients following intratumoral injection of an adenovirus vector expressing wild-type. P53 (Ad-p53).

The immune responses of 10 patients with advanced non-small cell lung cancer receiving monthly intratumoral injections of a recombinant adenovirus containing human wild-type p53 (Ad-p53) to adenovirus and transgene antigens were studied. The predominate cellular and humoral immune responses as measured by lymphocyte proliferation and neutralizing antibody (Ab) formation were to adenovirus serotype 5 vector antigens, with increased responses in posttreatment samples. Consistent alterations in posttreatment cellular and humoral immune responses to p53 epitopes were not observed, and cytotoxic Abs to human lung cancer cells were not generated. Patients in this study had evidence of an antitumoral effect of this treatment with prolonged tumor stability or regression; however, neither Abs to p53 protein nor increased lymphocyte proliferative responses to wild-type or mutant p53 peptides have been consistently detected.

Adenovirus-mediated p53 gene transfer in sequence with cisplatin to tumors of patients with non-small-cell lung cancer.

PURPOSE: To determine the safety and tolerability of adenovirus-mediated p53 (Adp53) gene transfer in sequence with cisplatin when given by intratumor injection in patients with non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Patients with advanced NSCLC and abnormal p53 function were enrolled onto cohorts receiving escalating dose levels of Adp53 (1 x 10(6) to 1 x 10(11) plaque-forming units [PFU]). Patients were administered intravenous cisplatin 80 mg/m(2) on day 1 and study vector on day 4 for a total of up to six courses (28 days per course). Apoptosis was determined by the terminal deoxynucleotidyl- transferase-dUTP nick-end labeling assay. Evidence of vector-specific sequences were determined using reverse-transcriptase polymerase chain reaction. Vector dissemination and biodistribution was monitored using a series of assays (cytopathic effects assay, Ad5 hexon enzyme-linked immunosorbent assay, vector-specific polymerase chain reaction assay, and antibody response assay). RESULTS: Twenty-four patients (median age, 64 years) received a total of 83 intratumor injections with Adp53. The maximum dose administered was 1 x 10(11) PFU per dose. Transient fever related to Adp53 injection developed in eight of 24 patients. Seventeen patients achieved a best clinical response of stable disease, two patients achieved a partial response, four patients had progressive disease, and one patient was not assessable. A mean apoptotic index between baseline and follow-up measurements increased from 0.010 to 0.044 (P =.011). Intratumor transgene mRNA was identified in 43% of assessable patients. CONCLUSION: Intratumoral injection with Adp53 in combination with cisplatin is well tolerated, and there is evidence of clinical activity.

The biologic basis for the use of retinoids in cancer prevention and treatment.

Retinoids (vitamin A and related molecules) are biologic agents that have demonstrated, in preclinical and clinical models, potent activity in the prevention and treatment of a variety of malignancies. Presented in this article is a review of recent clinical studies and correlative laboratory findings that advance our understanding of the biologic basis for the use of retinoids in cancer prevention and treatment.

Cisplatin, etoposide, and paclitaxel in the treatment of patients with extensive small-cell lung carcinoma.

PURPOSE: The combination of cisplatin, etoposide, and paclitaxel was studied in patients with extensive small-cell lung cancer in a phase I component followed by a phase II trial to determine the maximum-tolerated dose (MTD), characterize toxicity, and estimate response and median survival rates. PATIENTS AND METHODS: Forty-one patients were treated between October 1993 and April 1997. Doses for the initial cohort were cisplatin 75 mg/m(2) on day 1, etoposide 80 mg/m(2)/d on days 1 to 3, and paclitaxel 130 mg/m(2) on day 1 over 3 hours. Cycles were repeated every 3 weeks for up to six cycles. The MTD was reached in the first six patients. In these six patients and in the next 35 patients, who were entered onto the phase II trial, response and survival were estimated. RESULTS: At the initial dose level, one of six patients developed febrile neutropenia, and five of six achieved targeted neutropenia (nadir absolute granulocyte count, 100 to 1,000/microL) without any other dose-limiting toxicity, defining this level as the MTD. Grade 4 neutropenia was observed in 88 (47%) of 188 total courses administered at or less than the MTD. Neutropenia was associated with fever in only 17 (9%) of 188 courses, but two patients experienced neutropenic sepsis that was fatal. Nonhematologic toxicity greater than grade 2 was observed in 10 (5%) of 188 total courses, with fatigue, peripheral neuropathy, and nausea/vomiting most common. The overall objective response rate was 90% of 38 assessable patients: six complete responses (16%) and 28 partial responses(74%). Median progression-free and overall survival durations were 31 and 47 weeks, respectively. CONCLUSION: The combination of cisplatin, etoposide, and paclitaxel produced response and survival rates similar to those of other combinations and was well tolerated.

Loss of Fhit is frequent in stage I non-small cell lung cancer and in the lungs of chronic smokers.

Abnormalities of FHIT, a candidate tumor suppressor gene at 3p14.2, have been found frequently in multiple tumor types including non-small cell lung cancer (NSCLC). To investigate whether FHIT inactivation plays a role in early lung tumorigenesis, Fhit levels were determined by immunohistochemistry in tumors from 87 patients with stage I NSCLC and in 372 bronchial biopsy specimens from 86 chronic smokers without evidence of malignancy. We found that 49% of NSCLC specimens demonstrated significantly decreased staining or lack of staining for Fhit. However, Fhit expression status was not significantly associated with disease-free survival or overall survival. Analysis of a subset of 76 specimens on which microsatellite analysis at the FHIT locus was performed did not show a strong association between loss of heterozygosity at FHIT and Fhit expression, suggesting the presence of complex mechanisms of Fhit inactivation. Of 372 bronchial biopsies from chronic smokers, 86 biopsies (23%) exhibited decreased Fhit expression or lack of Fhit expression. In 37 of 86 (43%) subjects, decreased Fhit expression or lack of expression was observed in at least one biopsy site. Loss of Fhit expression was significantly higher in bronchial metaplastic lesions (23 of 49 lesions, 47%) than in histologically normal bronchial epithelium (63 of 323 specimens, 20%; P < 0.001). Smokers with a metaplasia index of > 15% had a higher frequency of loss of Fhit expression than those with a metaplasia index of < or = 15% (P = 0.015). Interestingly, current smokers had a higher rate of loss of Fhit expression than former smokers (P = 0.02). Our data indicate that Fhit expression is significantly reduced in a substantial number of early-stage NSCLC and preneoplastic lesions in chronic smokers. The association between cigarette smoking and Fhit expression suggests a role for FHIT in the initiation of smoking-related lung tumorigenesis.

Posttranslational mechanisms contribute to the suppression of specific cyclin:CDK complexes by all-trans retinoic acid in human bronchial epithelial cells.

Retinoids have demonstrated activity in the chemoprevention of aerodigestive tract cancer. Potentially contributing to their lung cancer chemopreventive effects, retinoids inhibit the growth of human bronchial epithelial (HBE) cells. We observed previously that all-trans retinoic acid (t-RA) arrests the growth of HBE cells in the G0 phase of the cell cycle through activation of retinoic acid receptor-dependent pathways, which enhances the association of E2F-4 with retinoblastoma protein family members, converting E2F into a transcriptional suppressor. In this study, we examined the mechanism by which t-RA blocks cell cycle progression in HBE cells and the possibility that this signaling event is blocked in non-small cell lung cancer (NSCLC) cells that are refractory to the growth inhibitory effects of t-RA. t-RA suppressed the expression and activity of cyclin D1, cyclin E, and cyclin-dependent kinases (CDK)-2 and CDK-4, increased expression of the CDK inhibitor p27, and shifted the retinoblastoma protein to a hypophosphorylated form. Posttranslational mechanisms contributed to the changes in CDK-2, CDK-4, and p27 levels, which, in the case of CDK-4, involved the ubiquitin-proteasome pathway. In contrast, despite retinoic acid receptor transcriptional activation, these signaling events did not occur in a NSCLC cell line that is refractory to growth inhibition by t-RA. These findings provide the first evidence that t-RA activates degradation of CDK-4 through the ubiquitin-proteasome pathway, a novel mechanism by which t-RA causes HBE cells to exit the cell cycle, and blockade of these signaling events may contribute to the development of retinoid resistance in NSCLC cells.