Gregory P. Kalemkerian

Peroxisome proliferator-activated receptor- γ activation inhibits tumor progression in non-small-cell lung cancer

The peroxisome proliferator-activated receptor-gamma (PPAR-γ) is a member of the nuclear hormone receptor superfamily of ligand-activated transcription factors and a crucial regulator of cellular differentiation. Differentiation-inducing and antiproliferative effects of PPAR-γ suggest that PPAR-γ agonists might be useful as effective anticancer agents. Few studies have examined the efficacy of these agonists in animal models of tumorigenesis, and their mechanism(s) of action are still not clear. Our studies indicate higher PPAR-γ expression in primary tumors from non-small-cell lung cancer (NSCLC) patients when compared to normal surrounding tissue. The expression of PPAR-γ was also observed in several NSCLC lines. The treatment of lung adenocarcinoma cells (A549) with troglitazone (Tro), a PPAR-γ ligand, enhanced PPAR-γ transcriptional activity and induced a dose-dependent inhibition of A549 cell growth. The observed growth arrest was predominantly due to the inhibition of cell proliferation without significant induction of apoptosis. Cell cycle analysis of Tro-treated cells revealed a cell cycle arrest at G0/G1 with concomitant downregulation of G0/G1 cyclins D and E. In addition, Tro treatment stimulated sustained Erk1/2 activation in A549 cells, suggesting the activation of a differentiation-inducing pathway. Furthermore, treatment of A549 tumor-bearing SCID mice with Tro or Pio inhibited primary tumor growth by 66.7% and significantly inhibited the number of spontaneous lung metastatic lesions. Collectively, our data demonstrate that activation of PPAR-γ impedes lung tumor progression and suggest that PPAR-γ ligands may serve as potential therapeutic agents for NSCLC.

Lung cancer in young patients: analysis of a Surveillance, Epidemiology, and End Results database.

PURPOSE A large community-based cancer registry was analyzed to determine if the clinicopathologic characteristics and/or survival rates of lung cancer patients under 50 years of age at diagnosis differ from those of patients 50 years of age or greater at diagnosis. PATIENTS AND METHODS Data regarding demographics, stage, histology, initial therapy, and survival were obtained on all patients with primary bronchogenic carcinoma registered in the metropolitan Detroit Surveillance, Epidemiology and End Results (SEER) registry from 1973 to 1992. RESULTS Of 31,266 patients, 9.0% were under 50 years of age at diagnosis. Females (40.1% v 31.2%; P < .001) and blacks (28.7% v 21.9%, P < .001) were overrepresented in the younger group compared with the older group. Younger patients had a significantly higher incidence of adenocarcinoma and were less likely to present with local-stage disease (18.6% v 25.2%; P < .001). Younger patients were significantly more likely to undergo surgery and/or combined-modality therapy. Relative survival at 5 years was significantly better in the younger group (16.1% v 13.4%; P < .001), mainly because of better survival in patients with local-stage disease (48.7% v 35.4%; P < .001). In a multivariate analysis, advanced-stage, nonsurgical initial therapy, age 50 years or greater at diagnosis, and male gender were independent negative prognostic factors. CONCLUSION The overrepresentation of females and blacks in the group of younger patients with lung cancer suggests an increased susceptibility to lung carcinogens in these populations. Overall, this study suggests that lung cancer is not a more aggressive disease in younger patients and that all patients with lung cancer should be managed along the same therapeutic guidelines.

Notch pathway activity identifies cells with cancer stem cell-like properties and correlates with worse survival in lung adenocarcinoma

PURPOSE The cancer stem cell theory postulates that tumors contain a subset of cells with stem cell properties of self-renewal, differentiation, and tumor initiation. The purpose of this study is to determine the role of Notch activity in identifying lung cancer stem cells. EXPERIMENTAL DESIGN We investigated the role of Notch activity in lung adenocarcinoma using a Notch GFP reporter construct and a γ-secretase inhibitor (GSI), which inhibits Notch pathway activity. RESULTS Transduction of lung cancer cells with Notch GFP reporter construct identified a subset of cells with high Notch activity (GFP-bright). GFP-bright cells had the ability to form more tumor spheres in serum-free media and were able to generate both GFP-bright and GFP-dim (lower Notch activity) cell populations. GFP-bright cells were resistant to chemotherapy and were tumorigenic in serial xenotransplantation assays. Tumor xenografts of mice treated with GSI had decreased expression of downstream effectors of Notch pathway and failed to regenerate tumors upon reimplantation in NOD/SCID mice. Using multivariate analysis, we detected a statistically significant correlation between poor clinical outcome and Notch activity (reflected in increased Notch ligand expression or decreased expression of the negative modulators), in a group of 443 patients with lung adenocarcinoma. This correlation was further confirmed in an independent group of 89 patients with adenocarcinoma in which Hes-1 overexpression correlated with poor overall survival. CONCLUSIONS Notch activity can identify lung cancer stem cell-like population and its inhibition may be an appropriate target for treating lung adenocarcinoma.

The Application of Molecular Diagnostic Studies Interrogating EGFR and KRAS Mutations to Stained Cytologic Smears of Lung Carcinoma

EGFR and KRAS mutation analyses are of increasing importance for guiding the treatment of non-small cell lung carcinomas. Insufficient cellularity of cell blocks can represent an impediment to the performance of these tests. We investigated the usefulness of cytologic direct smears as an alternative specimen source for mutation testing. Tumor cell-enriched areas from freshly prepared and archived rapid Romanowsky-stained direct smears in 33 cases of lung carcinoma were microdissected for DNA isolation and evaluated for EGFR and KRAS mutations. EGFR mutations were detected in 3 adenocarcinomas; 2 tumors had the L858R substitution and 1 an exon 19 deletion. KRAS mutations affecting codon 12, 13, or 61 were detected in 11 cases (8 adenocarcinomas and 3 non-small cell carcinomas). EGFR and KRAS mutations were mutually exclusive. Hence, archived and freshly prepared direct smears represent a robust and valuable specimen source for molecular studies, especially when cell blocks exhibit insufficient cellularity.

Racial differences in lung cancer

Although race, in and of itself, is not a relevant biologic variable, racial differences in disease characteristics and outcomes have been reported in many malignancies, including lung cancer. The lung cancer incidence rate in blacks has been consistently higher than that in whites for many years. This racial disparity is seen primarily in men and is significantly greater in younger age groups. The reason for higher lung cancer incidence rates in blacks remains unclear, but racial differences in smoking habits, socioeconomic variables, and the metabolism of tobacco carcinogens may all play an important role. Blacks are also more likely than whites to present with squamous cell carcinoma and with advanced-stage disease. A significant racial difference in survival rates has developed over the past 30 years, with a poorer prognosis noted in black patients, particularly those with local- and regional-stage disease. This disparity appears to be due to a lack of improvement in the survival of black patients with lung cancer, but the biological and/or societal basis for racial variations in survival have not been determined. In summary, significant racial differences exist in lung cancer incidence and survival rates. Further research is required to determine the factors responsible for these differences and to develop effective preventative and therapeutic interventions that will impact favorably on the incidence and prognosis of this disease.

ELEVATION OF PLASMA TGF-β1 DURING RADIATION THERAPY PREDICTS RADIATION-INDUCED LUNG TOXICITY IN PATIENTS WITH NON-SMALL-CELL LUNG CANCER: A COMBINED ANALYSIS FROM BEIJING AND MICHIGAN

PURPOSE To test whether radiation-induced elevations of transforming growth factor-beta1 (TGF-beta1) during radiation therapy (RT) correlate with radiation-induced lung toxicity (RILT) in patients with non-small-cell lung cancer (NSCLC) and to evaluate the ability of mean lung dose (MLD) to improve the predictive power. METHODS AND MATERIALS Eligible patients included those with Stage I-III NSCLC treated with RT with or without chemotherapy. Platelet-poor plasma was obtained pre-RT and at 4-5 weeks (40-50 Gy) during RT. TGF-beta1 was measured using an enzyme-linked immunosorbent assay. The primary endpoint was > or = Grade 2 RILT. Mann-Whitney U test, logistic regression, and chi-square were used for statistical analysis. RESULTS A total of 165 patients were enrolled in this study. The median radiation dose was 60 Gy, and the median MLD was 15.3 Gy. Twenty-nine patients (17.6%) experienced RILT. The incidence of RILT was 46.2% in patients with a TGF-beta1 ratio > 1 vs. 7.9% in patients with a TGF-beta1 ratio < or = 1 (p < 0.001), and it was 42.9% if MLD > 20 Gy vs. 17.4% if MLD < or = 20 Gy (p = 0.024). The incidence was 4.3% in patients with a TGF-beta1 ratio < or = 1 and MLD < or = 20 Gy, 47.4% in those with a TGF-beta1 ratio >1 or MLD > 20 Gy, and 66.7% in those with a TGF-beta1 ratio >1 and MLD > 20 Gy (p < 0.001). CONCLUSIONS Radiation-induced elevation of plasma TGF-beta1 level during RT is predictive of RILT. The combination of TGF- beta1 and MLD may help stratify the patients for their risk of RILT.

Biology of lung cancer.

Recent advances in basic research have greatly increased our understanding of the biologic events involved in the pathogenesis and progression of lung cancer. A multitude of genetic aberrations have been detected in both small-cell and non-small-cell lung cancer, many of which affect the function of known oncogenes and tumor-suppressor genes, which may serve as molecular targets for interventional trials. Recently identified abnormalities in oncogene expression and signal transduction pathways in premalignant lesions will be useful in devising future early diagnosis and chemoprevention studies. Numerous growth factor pathways control the proliferation and invasiveness of lung cancer cells and offer relatively tumor-specific targets for novel therapeutic approaches. Recent studies have defined several drug resistant mechanisms in lung cancer and have suggested methods for preventing and reversing treatment resistance. Insight into the biology of lung cancer will allow the improvement of current approaches to the prevention, diagnosis, and treatment of this devastating disease.

Characterization of 298 patients with lung cancer harboring MET Exon 14 skipping alterations

Background: The hepatocyte growth factor receptor gene (MET) exon 14 skipping (METex14) has recently been described a potential driver alteration in lung cancer targetable by mesenchymal‐to‐epithelial transition factor (MET) tyrosine kinase inhibitors (TKIs). Methods: Well‐validated hybrid capture–based comprehensive genomic profiling was performed at the request of individual treating physicians. Results: Of 11,205 lung cancers profiled by comprehensive genomic profiling, 298 (2.7%) carcinomas harbored alterations predicted to cause METex14, including adenosquamous (8.2%), sarcomatoid (7.7%), histologic subtype not otherwise specified (3.0%), adenocarcinoma (2.9%), squamous cell (2.1%), large cell (0.8%), and SCLC (0.2%). Acinar features were present in 24% of the METex14 samples. Six cases (2%) harbored MET Y1003X mutations affecting binding of the MET‐negative regulator, E3 ubiquitin protein ligase. The median age of all patients with METex14 was 73 years (range 43–95) and 60% were female. Concurrent, murine double minute gene (MDM2) amplification, cyclin‐dependent kinase 4 gene (CDK4) amplification, and EGFR amplification were observed in 35%, 21%, and 6.4% of patients with METex14, respectively. KRAS mutation was observed in 3% of cases. Concurrent MET amplification (METamp) (median copy number 10) was identified in 15% of METex14 samples. Significant differences in tumor mutational burden and type of the METex14 alterations were observed between the METamp and non‐METamp samples. Response to MET TKI was observed in both in patients with METamp and in patients without METamp METex14. Conclusion: Diverse targetable METex14 alterations were identified in patients with NSCLC across age groups, including elderly patients, and in all major NSCLC histologic subtypes with an overall frequency of 2.7%. These findings support the use of hybrid capture–based molecular profiling across NSCLC subtypes to identify patients who will potentially benefit from MET TKIs.

An Embryonic Stem Cell–Like Signature Identifies Poorly Differentiated Lung Adenocarcinoma but not Squamous Cell Carcinoma

Purpose: An embryonic stem cell (ESC) profile correlates with poorly differentiated breast, bladder, and glioma cancers. In this article, we assess the correlation between the ESC profile and clinical variables in lung cancer. Experimental Design: Microarray gene expression analysis was done using Affymetrix Human Genome U133A on 443 samples of human lung adenocarcinoma and 130 samples of squamous cell carcinoma (SCC). To identify gene set enrichment patterns, we used the Genomica software. Results: Our analysis showed that an increased expression of the ESC gene set and a decreased expression of the Polycomb target gene set identified poorly differentiated lung adenocarcinoma. In addition, this gene expression signature was associated with markers of poor prognosis and worse overall survival in lung adenocarcinoma. However, there was no correlation between this ESC gene signature and any histologic or clinical variable assessed in lung SCC. Conclusions: This work suggests that not all poorly differentiated non–small cell lung cancers exhibit a gene expression profile similar to that of ESC, and that other characteristics may play a more important role in the determination of differentiation and survival in SCC of the lung. (Clin Cancer Res 2009;15(20):6386–90)

Activity of dolastatin 10 against small-cell lung cancer in vitro and in vivo: induction of apoptosis and bcl-2 modification.

Purpose: Dolastatin 10 is a natural cytotoxic peptide which acts through the inhibition of microtubule assembly. Studies have suggested that such agents can induce apoptosis in association with bcl-2 phosphorylation. Since bcl-2 overexpression is common in small-cell lung cancer (SCLC), we evaluated the activity of dolastatin 10 in SCLC cell lines and xenografts. Methods: In vitro growth inhibition was evaluated with a standardized MTT assay and apoptosis with fluorescent microscopy and a TUNEL assay. Immunoblot analysis and phosphatase digestion were used to determine bcl-2 modification. In vivo activity was evaluated in subcutaneous and metastatic SCLC xenograft models in SCID mice. Results: Dolastatin 10 had growth inhibitory activity against four SCLC cell lines (NCI-H69, -H82, -H446, -H510) with IC50 values ranging from 0.032 to 0.184 nM. All four cell lines exhibited evidence of apoptosis after 48 h of exposure to 1.3 nM dolastatin 10. Immunoblot analysis revealed that 1.3 nM dolastatin 10 altered the electrophoretic mobility of bcl-2 in NCI-H69 and -H510 cells within 16 h of treatment. Incubation of protein extract from dolastatin 10-treated NCI-H69 and -H510 cells with calcineurin resulted in the disappearance of the altered mobility species, suggesting dolastatin 10-induced bcl-2 phosphorylation. In in vivo studies, 450 μg/kg of dolastatin 10 IV × 2 given after intravenous injection of NCI-H446 cells completely inhibited tumor formation. In established subcutaneous NCI-H446 xenografts, 450 μg/kg of dolastatin 10 IV induced apoptosis in the majority of tumor cells within 96 h, resulting in a log10 cell kill of 5.2 and an increase in median survival from 42 to 91 days. Conclusions: These findings suggest that dolastatin 10 has potent activity against SCLC and that the modulation of apoptotic pathways deserves further evaluation as an anticancer strategy.