Protein phosphatase 2A and DNA-dependent protein kinase are involved in mediating rapamycin-induced Akt phosphorylation

BACKGROUND

The mechanisms underlying rapamycin-induced Akt phosphorylation have not been fully elucidated.

RESULTS

Inhibition of PP2A or DNA-PK attenuates or abrogates rapamycin-induced Akt phosphorylation and co-inhibition of mTOR and DNA-PK enhances anticancer activity.

CONCLUSION

PP2A-dependent and DNA-PK-mediated mechanism is involved in rapamycin-induced Akt phosphorylation.

SIGNIFICANCE

A previously unknown mechanism underlying rapamycin-induced Akt phosphorylation and a novel strategy to enhance mTOR-targeted cancer therapy may be suggested. Inhibition of mammalian target of rapamycin complex 1 (mTORC1), for example with rapamycin, increases Akt phosphorylation while inhibiting mTORC1 signaling. However, the underlying mechanisms have not been fully elucidated. The current study has uncovered a previously unknown mechanism underlying rapamycin-induced Akt phosphorylation involving protein phosphatase 2A (PP2A)-dependent DNA protein kinase (DNA-PK) activation. In several cancer cell lines, inhibition of PP2A with okadaic acid, fostriecin, small T antigen, or PP2A knockdown abrogated rapamycin-induced Akt phosphorylation, and rapamycin increased PP2A activity. Chemical inhibition of DNA-PK, knockdown or deficiency of DNA-PK catalytic subunit (DNA-PKcs), or knock-out of the DNA-PK component Ku86 inhibited rapamycin-induced Akt phosphorylation. Exposure of cancer cells to rapamycin increased DNA-PK activity, and gene silencing-mediated PP2A inhibition attenuated rapamycin-induced DNA-PK activity. Collectively these results suggest that rapamycin induces PP2A-dependent and DNA-PK-mediated Akt phosphorylation. Accordingly, simultaneous inhibition of mTOR and DNA-PK did not stimulate Akt activity and synergistically inhibited the growth of cancer cells both in vitro and in vivo. Thus, our findings also suggest a novel strategy to enhance mTOR-targeted cancer therapy by co-targeting DNA-PK.

CHFR protein expression predicts outcomes to taxane-based first line therapy in metastatic NSCLC

PURPOSE

Currently, there is no clinically validated test for the prediction of response to tubulin-targeting agents in non-small cell lung cancer (NSCLC). Here, we investigated the significance of nuclear expression of the mitotic checkpoint gene checkpoint with forkhead and ringfinger domains (CHFR) as predictor of response and overall survival with taxane-based first-line chemotherapy in advanced stage NSCLC.

METHODS

We studied a cohort of 41 patients (median age 63 years) with advanced NSCLC treated at the Atlanta VAMC between 1999 and 2010. CHFR expression by immunohistochemistry (score 0-4) was correlated with clinical outcome using chi-square test and Cox proportional models. A cutoff score of "3" was determined by receiver operator characteristics analysis for "low" CHFR expression. Results were validated in an additional 20 patients who received taxane-based chemotherapy at Emory University Hospital and the Atlanta VAMC.

RESULTS

High expression (score = 4) of CHFR is strongly associated with adverse outcomes: the risk for progressive disease after first-line chemotherapy with carboplatin-paclitaxel was 52% in patients with CHFR-high versus only 19% in those with CHFR-low tumors (P = 0.033). Median overall survival was strongly correlated with CHFR expression status (CHFR low: 9.9 months; CHFR high: 6.2 months; P = 0.002). After multivariate adjustment, reduced CHFR expression remained a powerful predictor of improved overall survival (HR = 0.24; 95% CI, 0.1-0.58%; P = 0.002). In the validation set, low CHFR expression was associated with higher likelihood of clinical benefit (P = 0.03) and improved overall survival (P = 0.038).

CONCLUSIONS

CHFR expression is a novel predictive marker of response and overall survival in NSCLC patients treated with taxane-containing chemotherapy.

Soluble FAS ligand as a biomarker of disease recurrence in differentiated thyroid cancer

BACKGROUND

Reliable predictive biomarkers are required to address the challenge of disease recurrence after thyroid cancer surgery. For this study, the authors assessed the association of cellular-based and serum-based immunologic mediators with thyroid cancer recurrence.

METHODS

Leukocyte subset counts and immune regulatory cytokine levels were determined in peripheral blood samples using multiparameter flow cytometry and 51-panel, multiplex enzyme-linked immunosorbent assays, respectively. The functional activity of circulating B-lymphocytes, T-lymphocytes, and natural killer lymphocytes was assessed ex vivo. Differences in mean biomarker levels between defined patient groups and correlations between biomarkers and cancer recurrence were assessed using t tests or Wilcoxon tests and by univariate and multivariate analyses with Cox models. Optimal cutoff values of significantly correlated biomarkers that best predicted disease recurrence after surgery were established by receiver operating characteristics and were validated by using an optimal cutpoint determination algorithm.

RESULTS

In total, 35 patients were enrolled (median age, 49.4 year), including 24 women and 15 patients with recurrent disease; and there were 21 individuals in the control group. Patients without recurrence had higher levels of soluble FAS (tumor necrosis receptor superfamily, member 6) ligand (sFASL), transforming growth factor-β, regulatory T cells, and programmed death 1/ programmed death ligand 1-expressing leukocytes. sFASL (hazard ratio, 0.60; 95% confidence interval, 0.38-0.95; P = .031) and interferon-α (hazard ratio, 1.55; 95% confidence interval, 1.03-2.34; P = .038) were associated significantly with disease recurrence. There was a significant difference in progression-free survival between patient groups stratified by an sFASL optimal cutpoint of 15 pg/mL (log-rank P = .0009).

CONCLUSIONS

sFASL and IFN-α levels were correlated significantly with thyroid cancer recurrence and may be useful for risk-adapted surveillance strategies in patients with thyroid cancer.

A phase 1 Bayesian dose selection study of bortezomib and sunitinib in patients with refractory solid tumor malignancies

BACKGROUND

This phase 1 trial utilising a Bayesian continual reassessment method evaluated bortezomib and sunitinib to determine the maximum tolerated dose (MTD), dose-limiting toxicities (DLT), and recommended doses of the combination.

METHODS

Patients with advanced solid organ malignancies were enrolled and received bortezomib weekly with sunitinib daily for 4 weeks, every 6 weeks. Initial doses were sunitinib 25 mg and bortezomib 1 mg m(-2). Cohort size and dose level estimation was performed utilising the Escalation with Overdose Control (EWOC) adaptive method. Seven dose levels were evaluated; initially, sunitinib was increased to a goal dose of 50 mg with fixed bortezomib, then bortezomib was increased. Efficacy assessment occurred after each cycle using RECIST criteria.

RESULTS

Thirty patients were evaluable. During sunitinib escalation, DLTs of grade 4 thrombocytopenia (14%) and neutropenia (6%) at sunitinib 50 mg and bortezomib 1.3 mg m(-2) were seen. Subsequent experience showed tolerability and activity for sunitinib 37.5 mg and bortezomib 1.9 mg m(-2). Common grade 3/4 toxicities were neutropenia, thrombocytopenia, hypertension, and diarrhoea. The recommended doses for further study are bortezomib 1.9 mg m(-2) and sunitinib 37.5 mg. Four partial responses were seen. Stable disease >6 months was noted in an additional six patients.

CONCLUSION

Bortezomib and sunitinib are well tolerated and have anticancer activity, particularly in thyroid cancer. A phase 2 study of this combination in thyroid cancer patients is planned.

Targeting the PI3K/AKT/mTOR pathway: biomarkers of success and tribulation

PI3K/AKT/mTOR pathway is an established oncogenic driver in humans. Targeted biologic agents against components of this pathway have shown promising activity leading to the approval of the allosteric inhibitors of mTOR, everolimus, and temsirolimus for the treatment of advanced cancers of the kidney, breast, and pancreas. Despite the established and promising activity of this therapeutic strategy, the duration and quality of benefit remains suboptimal in unselected patients. Improved understanding of the biologic consequence of altered PI3K/AKT/mTOR signaling is informing the development of protein (phosphorylated forms of S6, AKT, eIF4e) and genetic (PIK3CA mutation, PTEN loss of function, TSC1 and TSC2 mutation, PIK3CA-GS genetic profile) biomarkers to identify patients most likely to benefit from this therapeutic strategy. This review provides an overview of the biologic rational and promising results of protein and genetic biomarkers for selecting patients appropriate for therapy with inhibitors of this pathway.

Unusual suspects: pulmonary opportunistic infections masquerading as tumor metastasis in a patient with adrenocorticotropic hormone-producing pancreatic neuroendocrine cancer

Pancreatic neuroendocrine tumors (p-NETs) are a rare group of neoplasms but with increasing incidence. The atypical complications that arise in the setting of functional endocrine tumors are underreported and therefore have not received sufficient attention and the necessary mention in the oncology literature. The clinical implications of these complications pose management challenges starting with the difficulty in establishing diagnosis, accurate staging and optimal treatment of the primary process. We present the case of a middle-aged woman diagnosed with adrenocorticotropic hormone-producing carcinoma arising from the pancreas whose case was complicated by excessive uncontrolled hypercortisolism and reactivation of pulmonary opportunistic infections that confounded her management. We believe that this case illustration will be of value to practicing oncologists and other groups of physicians who are called upon to participate in the multidisciplinary treatment of these relatively rare but highly challenging cases.

Phosphoglycerate mutase 1 coordinates glycolysis and biosynthesis to promote tumor growth

It is unclear how cancer cells coordinate glycolysis and biosynthesis to support rapidly growing tumors. We found that the glycolytic enzyme phosphoglycerate mutase 1 (PGAM1), commonly upregulated in human cancers due to loss of TP53, contributes to biosynthesis regulation in part by controlling intracellular levels of its substrate, 3-phosphoglycerate (3-PG), and product, 2-phosphoglycerate (2-PG). 3-PG binds to and inhibits 6-phosphogluconate dehydrogenase in the oxidative pentose phosphate pathway (PPP), while 2-PG activates 3-phosphoglycerate dehydrogenase to provide feedback control of 3-PG levels. Inhibition of PGAM1 by shRNA or a small molecule inhibitor PGMI-004A results in increased 3-PG and decreased 2-PG levels in cancer cells, leading to significantly decreased glycolysis, PPP flux and biosynthesis, as well as attenuated cell proliferation and tumor growth.

Single agent maintenance therapy for advanced stage non-small cell lung cancer: a meta-analysis

BACKGROUND

Maintenance therapy is a new treatment paradigm for advanced non-small cell lung cancer (NSCLC). We conducted a meta-analysis of randomized studies with single agent maintenance therapy.

METHODS

An electronic literature search of public databases (MEDLINE, EMBASE, Cochrane library) and manual search of relevant conference proceedings was performed. A formal meta-analysis was conducted using Comprehensive Meta Analysis software (Version 2.0). Outcome data were pooled and reported as hazard ratio (HR). The primary outcome of interest was overall survival (OS) and secondary outcome was progression free survival (PFS).

RESULTS

Twelve studies were included (5 meeting abstracts, 7 full manuscripts) with a total of 4286 patients (maintenance arm/control arm - 2449/1837, median age 61 years, males - 69%). The OS (HR 0.86, 95% confidence intervals [CI] 0.80-0.92; P=0.0003) and PFS (HR 0.80, 95% CI 0.77-0.84; P<0.0001) were superior with maintenance therapy. 'Switch' maintenance was associated with significant OS and PFS improvement (OS HR 0.84, 95% CI 0.77-0.91; P=0.00026; PFS HR 0.62, 95% CI 0.57-0.67; P<0.0001). Despite a modest improvement in PFS (HR 0.90, 95%CI 0.85-0.95; P=0.007), "continuation" maintenance was not associated with survival benefit (HR 0.927, 95%CI 0.78-1.09; P=0.33). Improvements in OS and PFS were observed with both EGFR-targeted agents (HR 0.83, 95% CI 0.74-0.92; P=0.004; HR 0.64, 95% CI 0.58-0.71 P<0.0001) and cytotoxic agents (HR 0.89, 95% CI 0.80-0.98; P=0.018; HR 0.85, 95% CI 0.80-0.89; P<0.0001).

CONCLUSIONS

Single agent maintenance therapy improves overall survival, though statistical significance was only noted with 'switch' maintenance.

The combination of RAD001 and NVP-BKM120 synergistically inhibits the growth of lung cancer in vitro and in vivo

This study focuses on determining whether the combination of NYP-BKM120 (BKM120) and RAD001 exerts enhanced therapeutic effect against lung cancer. The combination of BKM120 and RAD001 exerted synergistic inhibitory effects on the growth of lung cancer cells both in culture and in mouse xenograft model. This combination abrogated RAD001-induced Akt phosphorylation and exerted enhanced suppressive effect on 4EBP1 phosphorylation. Collectively, we suggest that the combination of RAD001 and BKM120 may be an effective regimen for treatment of lung cancer, hence warranting further evaluation of the combination in the clinic.

A systematic analysis of efficacy of second-line chemotherapy in sensitive and refractory small-cell lung cancer

INTRODUCTION

Small-cell lung cancer (SCLC) patients unresponsive or relapsing within 90 days after frontline chemotherapy have poor prognosis and are treated with regimens different from the first-line regimen. Potential differences in the efficacy of second-line therapy for refractory and sensitive SCLC have not been well studied.

METHODS

Studies that enrolled sensitive and refractory (relapse < 90 days or > 90 days) SCLC patients for second-line therapy were identified using electronic databases (MEDLINE, EMBASE, and Cochrane library), and meeting abstracts databases. A systematic analysis was conducted using Comprehensive Meta Analysis (version 2.2.048) software to calculate the odds ratio of response and 95% confidence interval. Median overall survival time for sensitive and resistant SCLC patients was compared by two-sided Student's t test. We tested for significant heterogeneity by Cochran's chi-square test and I-square index.

RESULTS

Twenty-one studies published between 1984 and 2011 were eligible for this analysis with a total of 1692 patients enrolled; 912 with sensitive and 780 with refractory SCLC. The overall response rate was 17.9% with a higher response rate of 27.7% (range, 0%-77%) for sensitive SCLC versus 14.8% (range, 0%-70%) for refractory patients; p=0.0001. Pooled overall odds ratio of response was 2.235 (95% confidence interval: 1.518-3.291; p=0.001) favoring patients with sensitive disease. Median overall survival time was 6.7 months with a weighted survival of 7.7 and 5.4 months for sensitive and refractory SCLC, respectively (p = 0.0035).

CONCLUSIONS

Refractory SCLC patients derive modest clinical benefit from second-line chemotherapy. However, response and survival outcomes are superior with chemosensitive disease.

Elevated expression of eukaryotic translation initiation factor 4E is associated with proliferation, invasion and acquired resistance to erlotinib in lung cancer

Eukaryotic translation initiation factor 4E (eIF4E) is the rate-limiting factor for cap-dependent translation initiation, which is known to regulate oncogenesis. Elevated eIF4E and its negative impact on prognosis in human non-small cell lung cancer (NSCLC) have been reported previously. However, its potential as a therapeutic target and role in regulation of sensitivity to EGFR inhibitors is an area of ongoing investigations. In this study, we detected increased levels of eIF4E in 16 human NSCLC cell lines compared with their normal bronchial epithelial cells. Consistently, human tissue array analysis showed that eIF4E expression was significantly higher in human NSCLC tissues than normal tissues. Inhibition of eIF4E using eIF4E siRNA inhibited the growth and invasion of NSCLC cells. These data suggest that eIF4E overexpression plays a crucial role in positive regulation of the growth and invasion of NSCLC cells. By proteomics, we found that eIF4E levels were elevated in erlotinib-resistant cell lines compared with the sensitive parental cell line. In agreement, assembly of the eIF4F cap complex and several oncogenic proteins regulated by the cap-dependent translation mechanism, were also increased in erlotinib-resistant cells. Thus, erlotinib-resistant cells exhibit elevated eIF4E expression and cap-dependent translation. Inhibition of eIF4F with different means (e.g., gene knockdown) downregulated c-Met expression and partially restored cell sensitivity to erlotinib, suggesting that elevated eIF4E contributes to development of erlotinib resistance, likely through positive regulation of c-Met expression. Taken together, we suggest that elevated eIF4E in NSCLC cells is associated with proliferation, invasion and acquired erlotinib resistance.

NNK promotes migration and invasion of lung cancer cells through activation of c-Src/PKCι/FAK loop

Cigarette smoking, either active or passive, is the most important risk factor in the development of human lung cancer. Mounting evidence indicates that cigarette smoke constituents not only contribute to tumorigenesis but also may increase the spread of cancer in the body. Nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is formed by nitrosation of nicotine and has been identified as the most potent carcinogen. NNK, an important component in cigarette smoke, may also promote tumor metastasis by regulating cell motility. Here we found that NNK can induce activation of a functionally interdependent protein kinase cascade, including c-Src, PKCι and FAK, in association with increased migration and invasion of human lung cancer cells. c-Src, PKCι and FAK are extensively co-localized in the cytoplasm. Treatment of cells with α(7) nAChR specific inhibitor α-bungarotoxin (α-BTX) blocks NNK-stimulated activation of c-Src, PKCι and FAK and suppresses cell migration and invasion. Intriguingly, NNK enhances c-Src/PKCι and PKCι/FAK bindings, indicating a potential mechanism by which these kinases activate each other. Specific disruption of c-Src, PKCι or FAK expression by RNA interference significantly reduces NNK-induced cell migration and invasion. These findings suggest that NNK-induced migration and invasion may occur in a mechanism through activation of a c-Src/PKCι/FAK loop, which can contribute to metastasis and/or development of human lung cancer.

Statistical learning methods as a preprocessing step for survival analysis: evaluation of concept using lung cancer data

BACKGROUND

Statistical learning (SL) techniques can address non-linear relationships and small datasets but do not provide an output that has an epidemiologic interpretation.

METHODS

A small set of clinical variables (CVs) for stage-1 non-small cell lung cancer patients was used to evaluate an approach for using SL methods as a preprocessing step for survival analysis. A stochastic method of training a probabilistic neural network (PNN) was used with differential evolution (DE) optimization. Survival scores were derived stochastically by combining CVs with the PNN. Patients (n = 151) were dichotomized into favorable (n = 92) and unfavorable (n = 59) survival outcome groups. These PNN derived scores were used with logistic regression (LR) modeling to predict favorable survival outcome and were integrated into the survival analysis (i.e. Kaplan-Meier analysis and Cox regression). The hybrid modeling was compared with the respective modeling using raw CVs. The area under the receiver operating characteristic curve (Az) was used to compare model predictive capability. Odds ratios (ORs) and hazard ratios (HRs) were used to compare disease associations with 95% confidence intervals (CIs).

RESULTS

The LR model with the best predictive capability gave Az = 0.703. While controlling for gender and tumor grade, the OR = 0.63 (CI: 0.43, 0.91) per standard deviation (SD) increase in age indicates increasing age confers unfavorable outcome. The hybrid LR model gave Az = 0.778 by combining age and tumor grade with the PNN and controlling for gender. The PNN score and age translate inversely with respect to risk. The OR = 0.27 (CI: 0.14, 0.53) per SD increase in PNN score indicates those patients with decreased score confer unfavorable outcome. The tumor grade adjusted hazard for patients above the median age compared with those below the median was HR = 1.78 (CI: 1.06, 3.02), whereas the hazard for those patients below the median PNN score compared to those above the median was HR = 4.0 (CI: 2.13, 7.14).

CONCLUSION

We have provided preliminary evidence showing that the SL preprocessing may provide benefits in comparison with accepted approaches. The work will require further evaluation with varying datasets to confirm these findings.

Oncogenic Ras and B-Raf proteins positively regulate death receptor 5 expression through co-activation of ERK and JNK signaling

Oncogenic mutations of ras and B-raf frequently occur in many cancer types and are critical for cell transformation and tumorigenesis. Death receptor 5 (DR5) is a cell surface pro-apoptotic death receptor for tumor necrosis factor-related apoptosis-inducing ligand and has been targeted in cancer therapy. The current study has demonstrated induction of DR5 expression by the oncogenic proteins Ras and B-Raf and revealed the underlying mechanisms. We demonstrated that both Ras and B-Raf induce DR5 expression by enforced expression of oncogenic Ras (e.g. H-Ras12V or K-Ras12V) or B-Raf (i.e. V600E) in cells and by analyzing gene expression array data generated from cancer cell lines and from human cancer tissues. This finding is further supported by our results that knockdown of endogenous K-Ras or B-Raf (V600E) reduced the expression of DR5. Importantly, we have elucidated that Ras induces DR5 expression through co-activation of ERK/RSK and JNK signaling pathways and subsequent cooperative effects among the transcriptional factors CHOP, Elk1, and c-Jun to enhance DR5 gene transcription. Moreover, we found that the majority of cancer cell lines highly sensitive to the DR5 agonistic antibody AMG655 have either Ras or B-Raf mutations. Our findings warrant further study on the biology of DR5 regulation by Ras and B-Raf, which may provide new insight into the biology of Ras and B-Raf, and on the potential impact of Ras or B-Raf mutations on the outcome of DR5-targeted cancer therapy.

Rapamycin induces Bad phosphorylation in association with its resistance to human lung cancer cells

Inhibition of mTOR signaling by rapamycin has been shown to activate extracellular signal-regulated kinase 1 or 2 (ERK1/2) and Akt in various types of cancer cells, which contributes to rapamycin resistance. However, the downstream effect of rapamycin-activated ERKs and Akt on survival or death substrate(s) remains unclear. We discovered that treatment of human lung cancer cells with rapamycin results in enhanced phosphorylation of Bad at serine (S) 112 and S136 but not S155 in association with activation of ERK1/2 and Akt. A higher level of Bad phosphorylation was observed in rapamycin-resistant cells compared with parental rapamycin-sensitive cells. Thus, Bad phosphorylation may contribute to rapamycin resistance. Mechanistically, rapamycin promotes Bad accumulation in the cytosol, enhances Bad/14-3-3 interaction, and reduces Bad/Bcl-XL binding. Rapamycin-induced Bad phosphorylation promotes its ubiquitination and degradation, with a significant reduction of its half-life (i.e., from 53.3-37.5 hours). Inhibition of MEK/ERK by PD98059 or depletion of Akt by RNA interference blocks rapamycin-induced Bad phosphorylation at S112 or S136, respectively. Simultaneous blockage of S112 and S136 phosphorylation of Bad by PD98059 and silencing of Akt significantly enhances rapamycin-induced growth inhibition in vitro and synergistically increases the antitumor efficacy of rapamycin in lung cancer xenografts. Intriguingly, either suppression of Bad phosphorylation at S112 and S136 sites or expression of the nonphosphorylatable Bad mutant (S112A/S136A) can reverse rapamycin resistance. These findings uncover a novel mechanism of rapamycin resistance, which may promote the development of new strategies for overcoming rapamycin resistance by manipulating Bad phosphorylation at S112 and S136 in human lung cancer.

Augmentation of NVP-BEZ235's anticancer activity against human lung cancer cells by blockage of autophagy

Autophagy is a cellular lysosomal degradation pathway essential for regulation of cell survival and death to maintain homeostasis. This process is negatively regulated by mammalian target of rapamycin (mTOR) signaling and often counteracts efficacy of certain cancer therapeutic agents. NVP-BEZ235 (BEZ235) is a novel, orally bioavailable dual PI3K/mTOR inhibitor that has exhibited promising activity against non-small cell lung cancer (NSCLC) in preclinical models. The current study focuses on evaluating the role of BEZ235 in regulating autophagy. BEZ235 was effective in inhibiting the growth of NSCLC cells including induction of apoptosis. It also potently induced the expression of type-II LC3, indicating induction of autophagy. When BEZ235 was used in combination with the lysosomal or autophagic inhibitor chloroquine (CQ), enhanced inhibitory effects on monolayer growth and colony formation of NSCLC cells was observed. In addition, enhanced induction of apoptosis was also detected in cells exposed to the combination of BEZ235 and CQ. Moreover, the combination of BEZ235 and CQ was more effective than each single agent alone in inhibiting the growth of NSCLC xenografts in nude mice. Thus, induction of autophagy by BEZ235 appears to be a survival mechanism that may counteract its anticancer effects. Based on these, we suggest a strategy to enhance BEZ235's anticancer efficacy by blockade of autophagy.

Human immunodeficiency virus-associated lung cancer in the era of highly active antiretroviral therapy

BACKGROUND

Lung cancer is the leading cause of death among non-acquired immunodeficiency syndrome (AIDS)-defining malignancies. Because highly active antiretroviral therapy (HAART) has improved the survival of patients with human immunodeficiency virus (HIV), the authors evaluated lung cancer outcomes in the HAART era.

METHODS

HIV-positive patients who were diagnosed with lung cancer at the authors' institution during the HAART era (1995-2008) were analyzed. Patient charts were reviewed for clinical and laboratory data. The CD4 count at diagnosis was treated as a continuous variable and subcategorized into distinct variables with 3 cutoff points (50 cells/mL, 200 cells/mL, and 500 cells/mL). Pearson correlation coefficients were estimated for each covariate studied. Survival was determined by using the Kaplan-Meier method.

RESULTS

Of 80 patients, 73 had nonsmall cell lung cancer. Baseline characteristics were as follows: median patient age, 52 years; male, 80%; African Americans, 84%; injection drug users, 25%; smokers, 100%; and previous exposure to antiretroviral agents, 55%. At the time of cancer diagnosis, the mean CD4 count was 304 cells/mL, and the mean viral load was 82,420 copies/mL. The latency between HIV diagnosis and lung cancer diagnosis was significantly shorter among women (4.1 years vs 7.7 years; P = .02), and 71% of patients received anticancer therapy. The 1-year and 3-year survival rates for stage IIIB/IV were 25% and 0%, respectively. Grade 3/4 toxicities occurred in 60% of patients who received chemoradiation versus 36% of patients who received chemotherapy. Cancer-related survival was better for patients with CD4 counts >200 cells/mL (P = .0298) and >500 cells/mL (P = .0076).

CONCLUSIONS

The latency from diagnosis of HIV to lung cancer was significantly shorter for women. Although outcomes for patients with lung cancer who have HIV remain poor, a high CD4 count was associated with improved lung cancer-related survival.

The combination of RAD001 and NVP-BEZ235 exerts synergistic anticancer activity against non-small cell lung cancer in vitro and in vivo

The phosphoinositide 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) signaling axis has emerged as a novel target for cancer therapy. Agents that inhibit PI3K, mTOR or both are currently under development. The mTOR allosteric inhibitor, RAD001, and the PI3K/mTOR dual kinase inhibitor, BEZ235, are examples of these agents. We were interested in developing strategies to enhance mTOR-targeted caner therapy. In this study, we found that BEZ235 alone effectively inhibited the growth of rapamycin-resistant cancer cells. Interestingly, the combination of sub-optimal concentrations of RAD001 and BEZ235 exerted synergistic inhibition of the growth of human lung cancer cells along with induction of apoptosis and G1 arrest. Furthermore, the combination was also more effective than either agent alone in inhibiting the growth of lung cancer xenografts in mice. The combination showed enhanced effects on inhibiting mTOR signaling and reducing the expression of c-Myc and cyclin D1. Taken together, our results suggest that the combination of RAD001 and BEZ235 is a novel strategy for cancer therapy.

Abstract 1953: Elevated eukaryotic translation initiation factor 4E (eIF4E) is involved in erlotinib resistance

The epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, erlotinib and gefitinib, are effective therapies for non-small cell lung cancer (NSCLC) with somatic mutations in EGFR. However, all patients eventually develop resistance (i.e., acquired resistance) to these agents. Thus, there is a great challenge and urgent need to understand the underlying mechanism so as to develop effective strategies to overcome the resistance. Eukaryotic translation initiation factor 4E (eIF4E) is the rate-limiting factor for cap-dependent translation initiation, a well known mechanism that regulates oncogenesis. In human cancers, increased eIF4E expression has been documented repeatedly to be associated with malignant progression. Accordingly therapeutic suppression of eIF4E expression (e.g., with eIF4E antisense oligonucleotides) effectively reduces tumor growth. However, the role of eIF4E in regulation of erlotinib resistance has not been studied. In this study, we detected increased levels of eIF4E in 16 human NSCLC cell lines compared with their normal bronchial epithelial cells. Consistently, human tissue array analysis showed that eIF4E expression was significantly higher in human NSCLC tissues than normal tissues. Inhibition of eIF4E using eIF4E siRNA substantially inhibited the growth of NSCLC cells. These data suggest that eIF4E overexpression plays a crucial role in supporting the growth of NSCLC cells. By SILAC proteomic and subsequent Western blot analysis, we found that eIF4E levels were substantially elevated in erlotinib-resistant cell line (i.e., HCC827/ER) compared with the sensitive parental cell line (i.e., HCC827). In agreement, assembly of the eIF4F cap complex and several oncogenic proteins such as HIF1α, c-Myc, and Mcl-1, which are regulated by the cap-dependent translation mechanism, were also increased in HCC827/ER cells. Thus, it appears that erlotinib-resistant cells exhibit elevated eIF4E expression and cap-dependent translation. Inhibition of eIF4E with either siRNA or the small molecule eIF4E inhibitor, 4EGI-1, in HCC828/ER cells, partially restored cell sensitivity to erlotinib, suggesting that elevated eIF4E in part contributes to development of erlotinib resistance. In addition, we detected increased levels of eIF4E mRNA in HCC827/ER cells, suggesting that elevated levels of elF4E protein are likely due to increased transcription. Our ongoing work is devoted to understand how eIF4E levels are elevated during the development of erlotinib resistance. (This study was supported by the Georgia Cancer Coalition Distinguished Cancer Scholar award, NIH/NCI RO1 CA118450 and PO1 CA116676, and Emory Winship Cancer Institute CCB seed grant; SY Sun, FR Khuri, SS Ramaligam and RK Owonikoko are Georgia Cancer Coalition Distinguished Cancer Scholars)

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1953. doi:10.1158/1538-7445.AM2011-1953

Abstract 1132: Oncogenic role of EAPII/TTRAP in lung cancer development and its activation of MAPK-ERK pathway

Cancer progression involves multiple complex and interdependent steps including progressive proliferation, angiogenesis and metastases. The complexity of these processes requires a comprehensive elucidation of the integrated signaling networks for better understanding. EAPII/TTRAP interacts with multiple cancer-related proteins, but its biological significance in cancer development remains unknown. In this report we identified the elevated level of EAPII/TTRAP protein in non-small cell lung carcinoma (NSCLC) patients and NSCLC cell lines in culture. The oncogenic role of EAPII in lung cancer development was demonstrated using NSCLC cells with genetic manipulations that influence EAPII expression: EAPII overexpression increases proliferation of NSCLC cells with an accelerated transition of cell cycle and facilitates xenograft tumor growth in vivo; EAPII knockdown results in apoptosis of NSCLC cells and reduces xenograft tumor formation. To further explore the mechanism of EAPII's oncogenic role in lung cancer development and to elucidate the potential signaling pathway(s) that EAPII may impact, we employed antibody array to investigate the alternation of the major signaling pathways in NSCLC cells with altered EAPII level. We found that EAPII overexpression significantly activated Raf-1 and ERK1/2, but not JNK and p38 pathways. Consistently, the protein and mRNA levels of MYC and cyclin D1, which are targets of the mitogen-activated protein kinases/extracellular signal-regulated kinases (MAPK-ERK) pathway, are significantly increased by EAPII overexpression. Taken together, we demonstrated that EAPII is an oncogenic factor and the activation of MAPK-ERK signaling pathway by EAPII may contribute to lung cancer development.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1132. doi:10.1158/1538-7445.AM2011-1132

Abstract 2567: Preclinical evaluation of Poly (ADP) Ribose Polymerase (PARP) enzyme inhibitor, ABT-888, in combination with cytotoxic agents in small cell lung cancer (SCLC)

The induction of DNA damage underlies the efficacy of cytotoxic chemotherapy agents for the treatment of SCLC. Poly (ADP) Ribose Polymerase (PARP) enzyme plays a key role in the cellular machinery responsible for DNA damage repair. Although inhibition of this enzyme using pharmacological inhibitor is postulated to enhance the cytotoxicity of DNA-damaging cytotoxic chemotherapy, this has not been previously studied in SCLC. The present work evaluated the interaction between ABT-888 and cytotoxic chemotherapy in SCLC.

A panel of SCLC cell lines (H146, H69, H187, H209, and H182) was employed for this work. Exponentially growing cells were treated by continuous exposure for 48-72 h to vehicle, ABT-888 and cytotoxic agents (cisplatin, carboplatin, etoposide) in the presence and absence of ABT-888. Surviving cell fraction and growth inhibition was determined using MTS assay. Sequence dependence interaction was assessed by alternating the sequence of administration of ABT-888 relative to the cytotoxic agents. Western blot assay was performed to assess for PARP inhibition, changes in markers of apoptosis (cleaved PARP and caspase), DNA damage (gamma-H2AX) and other DNA damage repair pathway proteins (ERCC1, DNA-PK, Ku80, ATM, ATR and BRCA1) under different treatment conditions. ABT-888 showed negligible cytotoxicity as a single agent. Co-administration of ABT-888 and chemotherapeutic agents resulted in enhanced cytotoxicity of cisplatin, carboplatin and to a lesser extent, etoposide, in a cell specific and dose-dependent manner. High concentrations (50uM) of ABT-888 produced up to 7-fold reduction in IC50 concentrations of cytotoxic agents while low concentration (5uM) of ABT-888 produced up to 2-fold reduction in IC50 concentrations. There was no sequence dependence interaction between ABT-888 and the cytotoxic agents. Time-course experiments showed down modulation of DNA protein kinase (DNA-PK) levels at 24 hours, which correlated with onset of apoptosis as assessed by PARP and caspase cleavage. Moreover, high basal expression of DNA-PK correlated with reduced potentiation of cytotoxicity by ABT-888 in H128 cell line. These results would support clinical evaluation of ABT-888 plus cytotoxic chemotherapy in patients with SCLC. Furthermore, DNA-PK level may serve as a predictive biomarker of efficacy of PARP inhibitor therapy. Our in vitro finding is currently being tested using in vivo animal model. (This work was supported through the Georgia Cancer Coalition Distinguished Scholar Award to TK Owonikoko, SS Ramalingam, FR Khuri and S Sun and the NIH/NCI Program Project P01 grant CA116676).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2567. doi:10.1158/1538-7445.AM2011-2567

Lung cancer: New biological insights and recent therapeutic advances

Approximately 1.6 million new cases of lung cancer are diagnosed each year throughout the world. In many countries, the mortality related to lung cancer continues to rise. The outcomes for patients with all stages of lung cancer have improved in recent years. The use of systemic therapy in conjunction with local therapy has led to improved cure rates in both resectable and unresectable patient groups. For patients with advanced stage disease, modest but real improvements in overall survival and quality of life have been achieved with systemic chemotherapy. A major focus of research has been the development of molecularly targeted agents and the identification of biomarkers for patient selection. Patients with non-small cell lung cancer with mutations in the epidermal growth factor receptor (EGFR) tyrosine kinase domain achieve response rates of greater than 70% and superior progression-free survival when treated with an EGFR tyrosine kinase inhibitor compared with standard chemotherapy. This has now emerged as the preferred therapeutic approach for the subset of patients with a mutation in exons 19 or 21 of the EGFR. Another promising targeted approach involves the use of an anaplastic lymphoma kinase (ALK) inhibitor in patients with a translocation involving the echinoderm microtubule-associated protein-like 4 (EML4) and -ALK genes. Finally, a paradigm shift in favor of maintenance therapy for patients with advanced stage disease has gained strength from recent data. All of these advances have been made possible by developing a greater understanding of the biology, the discovery of novel anticancer agents, and improved supportive care measures. This article reviews the major strides made in the treatment of lung cancer in the recent past.