Abstract 2263: Autophagy protects against Src tyrosine kinase inhibitor treatment in non-small cell lung cancer cells via a novel miR-106a/ULK1 pathway

Autophagy is a bulk degradation mechanism mainly involved in cell survival responses to a variety of stress stimuli. Its role in tumorigenesis is still ambiguous. Low levels of basal autophagy are crucial in order to sustain cellular homeostasis thereby also contributing to tumor prevention, whereas autophagy induction upon a variety of anti-cancer treatments is often involved in resistance mechanism to therapy. Src tyrosine kinase inhibitors (TKIs) inhibit cell migration and invasion in non-small cell lung cancer (NSCLC) cells. In clinical trials, however, they show modest activity in combination with chemotherapeutic agents. We hypothesized that cytoprotective autophagy plays a role in resistance mechanisms against Src TKIs. We found a marked induction of autophagic activity in NSCLC cell lines (A549, H460, H1299) treated with two different Src TKIs (saracatinib, dasatinib) as measured by increased LC3-I to -II conversion, increased GFP-LC3 dot formation, and decreased p62/SQSTM1 protein expression. Most importantly, the addition of pharmacological autophagy inhibitors (chloroquine, bafilomycin) in combination with Src TKI inhibitors resulted in cell death as compared to only decreased migration by Src TKI treatment alone. Next, we identified ULK1 as a key player in Src TKI-induced autophagy using a set of lentiviral vectors expressing shRNAs targeting ATG genes. Src TKIs significantly induced ULK1 mRNA and protein expression and knocking down ULK1 significantly attenuated Src TKI-induced autophagy. Furthermore, to exclude Src inhibition-independent effects of saracatinib and dasatinib on ULK1 expression, we targeted Src by RNAi and found similar induction of ULK1 as seen with the Src TKI treatment. We further investigated if micro(mi)RNAs are involved in ULK1 regulation during Src inhibitor treatment. Using miRNA target identification software and 3′-UTR luciferase reporter assays we identified miR-106a as ULK1-targeting miRNA. Incubating NSCLC cells with Src inhibitors resulted in a dose-dependent decrease of miR-106a paralleled by an increase in ULK1 expression. Moreover, ectopic expression of miR-106a and anti-miR-106a in NSCLC cell lines caused decreased and increased ULK1 expression upon Src inhibition, respectively. Importantly, similar to the pharmacological autophagy inhibition and or knocking down ULK1, expression of miR-106a enhanced the cytotoxicity of Src TKIs. Lastly, we found significantly higher miR-106a levels in human lung adenocarcinoma compared to matched normal lung tissue (n=23), whereas ULK1 mRNA expression levels were significantly lower (p<0.0002) in tumor tissue than in normal lung tissue. In conclusion, Src inhibitors induce protective autophagy in NSCLC cells that is mediated via miR-106 and its target ULK1. Combining Src and autophagy inhibitors may represent attractive treatment option for certain NSCLC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2263. doi:1538-7445.AM2012-2263

Abstract B30: Src tyrosine kinase inhibitors activate protective, ULK1-dependent autophagy by downregulating oncomir-106-393-cluster expression in non-small cell lung cancer cells

Autophagy has been proposed to play a role as cytoprotective mechanism for tumor cell survival under unfavorable conditions and upon anticancer treatment. In lung cancer autophagy is mostly studied as possible resistance mechanism to therapy. There is increasing evidence that protective autophagy occurs upon various types of anti-cancer treatments, including chemo- and radiation therapy. Src tyrosine kinase inhibitors (TKIs) have been shown to inhibit cell migration and invasion in non-small cell lung cancer (NSCLC) cell lines. In clinical trials, however, they show modest activity in combination with chemotherapeutic agents. In the current study we show a marked induction of autophagic activity upon incubation of NSCLC cell lines with Src TKIs as measured by an increased LC3-I to -II conversion, a significant increase in GFP-LC3 dot formation, and a decrease in p62/SQSTM1 protein expression. Increased autophagic activity was found in three NSCLC cell lines (A549, H460, H1299) with two different Src TKIs (saracatinib, dasatinib). Interestingly, the addition of pharmacological autophagy inhibitors such as chloroquine or bafilomycin resulted in cell death in combination with Src TKI treatment. Moreover, we found that Src TKI-induced autophagy is associated with ULK1 expression in all three cell lines investigated. This effect was Src-specific since knocking down endogenous Src using RNAi resulted in a similar induction of ULK1. Using shRNA targeting ULK1 we showed that Src inhibitor induced autophagy is ULK1-dependent. Furthermore, ULK1 is a novel target of microRNA (miR)-106a as shown by ULK1 3′-UTR luciferase experiments and ectopic expression of miR-106a and antimiR-106a in NSCLC cell lines resulting in decreased and increased ULK1 expression upon Src inhibition, respectively. Lastly, in human lung adenocarcinoma compared to matched normal lung tissue (n = 23) miR-106a levels were significantly increased (p<0.0001) whereas ULK1 mRNA expression levels were significantly lower (p<0.0002) in tumor tissue. In conclusion, Src inhibitor-induced protective autophagy might explain their low success in clinical trials. Autophagy induced by Src TKIs depends on ULK1 and combining Src with autophagy inhibitors results in massive cell death as compared to single treatments. Furthermore, downregulation of the ULK1 targeting miR-106a upon Src inhibition allows for the induction of protective autophagy. Combining Src and autophagy inhibitors or Src inhibitors and miR-106a expression may represent attractive treatment options for NSCLC.

Abstract 3987: Src regulates inhibitor of differentiation 1 (Id1) via c-Myc induced repression of microRNA-29b: Implications for invasion of lung cancer cells and their resistance against Src inhibitors

Background: Src and Id1 mediate cancer cell invasion and are frequently co-expressed in non-small cell lung cancer (NSCLC). We previously demonstrated that Src regulates Id1 in human lung cancer cells. MicroRNAs (miRNAs) are noncoding RNAs that regulate gene expression by inducing translational inhibition or cleavage of their target mRNAs. The current study aimed at identifying miRNAs controlled by Src that target Id1, and to test if modulation of these miRNAs and Id1 in NSCLC cells leads to resistance against Src inhibitors.

Methods: The study included the following human lung cancer cell lines: A549, H460, H1299, H820, HCC827. Cells were incubated with the Src inhibitors Saracatinib and Dasatinib and miRNA was extracted. To assess miRNA expression profiles, we used TaqMan® Array MicroRNA Cards (Applied Biosystems). Western Blotting was performed using antibodies for Src, phospho-Src, Id1, c-Myc, active beta-Catenin and Actin. Id1 and miR-29b transcript levels were measured using real-time quantitative RT-PCR. Lentiviral vectors expressing pre-miR-29b, anti-sense miR-29b, Id1 and c-Myc were used. Migration was tested with wound healing assays. For invasion matrigel coated membranes for transwell assays were used. Formalin-fixed and paraffin-embedded adenocarcinoma samples and matched lung tissue from 23 patients were used for miRNA expression analysis.

Results: Upon incubation of A549 cells with Saracatinib, miR-29b was the most highly upregulated miRNA with a predicted binding site in the Id1 3’UTR. Indeed, Id1 3’UTR luciferase reporter assays revealed direct binding of miR-29b to the Id1 3’UTR, but not to a mutated Id1 3’UTR. Anti-miR-29b enhanced Id1 mRNA and protein levels and significantly increased cell migration and invasion (p=0.0006). Anti-miR-29b or Id1 overexpression abolished the effects of Src inhibitors on invasion and migration. In contrast, transfection with pre-miR-29b suppressed Id1 and significantly reduced cell migration and invasion (p<0.00001). Overexpression of c-Myc repressed the level of miR-29b and induced the expression of Id1. Saracatinib and Dasatinib decreased active beta-Catenin, c-Myc and Id1 levels, and increased miR-29b levels in a dose-dependent manner. In 19 of 23 human lung adenocarcinoma biopsies, miR-29b was significantly downregulated compared with matched normal lung tissue (p=0.031). miR-29b was a strong prognostic factor for event-free (p=0.003) and overall survival (p=0.04)

Conclusions: These results demonstrate that Id1 is a direct target of miR-29b, which in turn is regulated by Src, active beta-Catenin and c-Myc. Therefore, miR-29b is involved in lung cancer cell migration and invasion. Furthermore, miR-29b is downregulated in human lung adenocarcinomas, and may be involved in the resistance of lung cancer cells against Src kinase inhibitors.

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 3987. doi:10.1158/1538-7445.AM2011-3987

Adherence to ESMO clinical recommendations for prophylaxis of chemotherapy-induced nausea and vomiting

BACKGROUND

We assessed adherence to the European Society of Medical Oncology (ESMO)/Multinational Association of Supportive Care in Cancer recommendations for prophylaxis of chemotherapy-induced nausea and vomiting (CINV) at our institution.

PATIENTS AND METHODS

The charts of 299 patients starting a new chemotherapy between November 2008 and April 2009 were reviewed. Baseline characteristics and prophylaxis of CINV during the first cycle were recorded, and adherence to ESMO recommendations was determined. Chi-square tests and logistic regression were used to test for predictors of adherence.

RESULTS

Prophylaxis of acute CINV was not adherent in 39% of the patients: 39 of 54 patients with low emetogenic chemotherapy had a serotonin antagonist, and 24 of 100 with moderately emetogenic therapy had a neurokinin antagonist. Nevertheless, 71% of the patients treated with highly emetogenic therapy received the guideline-specified prescription. Prophylaxis of delayed CINV was not adherent in 89% of the patients: 101 of 125 patients with highly or moderately emetogenic single-day chemotherapy received a serotonin antagonist. Male gender (odds ratio (OR) 0.484, 95% confidence interval (CI) 0.291-0.806; P = 0.005) and hematologic neoplasia (OR 2.151, 95% CI 1.19-3.887; P = 0.011) were independent predictors of non-adherence. Age (OR 0.981, 95% CI 0.964-0.998; P = 0.029) and inpatient treatment (OR 0.457, 95% CI 0.25-0.836; P = 0.011) indicated a lower risk of non-adherence.

CONCLUSION

Contrary to older studies reporting frequent omissions of corticosteroids, the current study demonstrated significant overuse of serotonin antagonists for prophylaxis of delayed CINV.

Cetuximab in combination with chemoradiotherapy before surgery in patients with resectable, locally advanced esophageal carcinoma: a prospective, multicenter phase IB/II Trial (SAKK 75/06)

PURPOSE

This multicenter phase IB/II trial investigated cetuximab added to preoperative chemoradiotherapy for esophageal cancer.

PATIENTS AND METHODS

Patients with resectable, locally advanced esophageal cancer received two 3-week cycles of induction chemoimmunotherapy (cisplatin 75 mg/m(2) day 1, docetaxel 75 mg/m(2) day 1, cetuximab 250 mg/m(2) days 1, 8,15 [400 mg/m(2) loading dose]) followed by chemoimmunoradiation therapy (CIRT) and surgery. CIRT consisted of 45 Gy radiotherapy (RT) plus concurrent cisplatin 25 mg/m(2) and cetuximab 250 mg/m(2) weekly for 5 weeks in cohort 1. If fewer than three of seven patients experienced limiting toxicity (LT), the next seven patients also received docetaxel (20 mg/m(2) weekly × 5). If fewer than three patients experienced LTs, 13 additional patients were treated at this dose.

RESULTS

In total, 28 patients (median age, 64 years) with predominantly node-positive (82%) esophageal adenocarcinoma (15 patients) or squamous cell carcinoma (13 patients) were enrolled and 24 (86%) completed the entire trimodal therapy. During CIRT, no LT occurred, rash was not exacerbated within the RT field, and the main grade 3 toxicities were esophagitis (seven patients), anorexia (three), fatigue (three), and thrombosis (two). Surgery (R0 resection) was performed in 25 patients. Anastomotic leakage occurred in three patients: two recovered spontaneously and one successfully underwent re-operation. There were no deaths at 30 days and no treatment-related mortality after 12 months. Nineteen patients (68%) showed complete or near complete pathologic regression.

CONCLUSION

Adding cetuximab to preoperative chemoradiotherapy is feasible without increasing postoperative mortality. Phase III investigation has begun based on the high histopathologic response and R0 resection rate.

Src inhibitors in lung cancer: current status and future directions

Src tyrosine kinases regulate multiple genetic and signaling pathways involved in the proliferation, survival, angiogenesis, invasion, and migration of various types of cancer cells They are frequently expressed and activated in many cancer types, including lung cancer. Several Src inhibitors, including dasatinib, saracatinib, bosutinib, and KX2-391, are currently being investigated in clinical trials. Preliminary results of the use of single-agent Src inhibitors in unselected patients with lung cancer show that these inhibitors have a favorable safety profile and anticancer activity. Their combination with cytotoxic chemotherapy, other targeted therapy, and radiation therapy is currently being explored. In this review, we summarize the rationale for and the current status of Src inhibitor development and discuss future directions based on emerging preclinical data.

The stem cell gene "inhibitor of differentiation 1" (ID1) is frequently expressed in non-small cell lung cancer

AIMS

Inhibitor of differentiation 1 (ID1) plays a role in cellular differentiation, proliferation, angiogenesis and tumor invasion. As shown recently, ID1 is positively regulated by the tyrosine kinase SRC in lung carcinoma cell lines and with that appears as a potential new therapeutic target in non-small cell carcinoma (NSCLC). To substantiate this hypothesis we examined ID1, SRC and matrix metalloproteinase-9 (MMP-9) immunohistochemically in human NSCLC specimens.

METHODS

From 61 consecutive patient tissue samples of a tumor tissue bank a one core tissue microarray (TMA) was produced and whole slide tissue samples of preinvasive lesions used. The staining of commercial antibodies was assessed by the H-score. Statistical analyses based on Spearman's rank correlation coefficient.

RESULTS

ID1 was expressed in the nucleus in 70% of squamous cell carcinomas and 50% of non-squamous cell carcinomas and in vascular endothelium of non-tumor tissue. Cytoplasmic staining was found in all samples for SRC and in 93% for MMP-9. ID1-positive tissue samples co-expressed SRC and MMP-9 in 94%. In non-squamous cell carcinomas, H-scores of ID1 and SRC correlated with each other (p=0.04). H-score of MMP-9 correlated with tumor grade (p=0.04). The carcinoma findings were reflected in preinvasive lesions.

CONCLUSIONS

We describe for the first time the immunohistochemical expression of ID1 in the majority of NSCLC samples. The almost general co-expression of ID1, SRC and MMP-9 supports their cooperation in vivo and warrants further investigation of ID1 as a therapeutic target.

Japanese-US common-arm analysis of paclitaxel plus carboplatin in advanced non-small-cell lung cancer: a model for assessing population-related pharmacogenomics

PURPOSE To explore whether population-related pharmacogenomics contribute to differences in patient outcomes between clinical trials performed in Japan and the United States, given similar study designs, eligibility criteria, staging, and treatment regimens. METHODS We prospectively designed and conducted three phase III trials (Four-Arm Cooperative Study, LC00-03, and S0003) in advanced-stage, non-small-cell lung cancer, each with a common arm of paclitaxel plus carboplatin. Genomic DNA was collected from patients in LC00-03 and S0003 who received paclitaxel (225 mg/m(2)) and carboplatin (area under the concentration-time curve, 6). Genotypic variants of CYP3A4, CYP3A5, CYP2C8, NR1I2-206, ABCB1, ERCC1, and ERCC2 were analyzed by pyrosequencing or by PCR restriction fragment length polymorphism. Results were assessed by Cox model for survival and by logistic regression for response and toxicity. Results Clinical results were similar in the two Japanese trials, and were significantly different from the US trial, for survival, neutropenia, febrile neutropenia, and anemia. There was a significant difference between Japanese and US patients in genotypic distribution for CYP3A4*1B (P = .01), CYP3A5*3C (P = .03), ERCC1 118 (P < .0001), ERCC2 K751Q (P < .001), and CYP2C8 R139K (P = .01). Genotypic associations were observed between CYP3A4*1B for progression-free survival (hazard ratio [HR], 0.36; 95% CI, 0.14 to 0.94; P = .04) and ERCC2 K751Q for response (HR, 0.33; 95% CI, 0.13 to 0.83; P = .02). For grade 4 neutropenia, the HR for ABCB1 3425C-->T was 1.84 (95% CI, 0.77 to 4.48; P = .19). CONCLUSION Differences in allelic distribution for genes involved in paclitaxel disposition or DNA repair were observed between Japanese and US patients. In an exploratory analysis, genotype-related associations with patient outcomes were observed for CYP3A4*1B and ERCC2 K751Q. This common-arm approach facilitates the prospective study of population-related pharmacogenomics in which ethnic differences in antineoplastic drug disposition are anticipated.

Aurora kinases as anticancer drug targets

The human aurora family of serine-threonine kinases comprises three members, which act in concert with many other proteins to control chromosome assembly and segregation during mitosis. Aurora dysfunction can cause aneuploidy, mitotic arrest, and cell death. Aurora kinases are strongly expressed in a broad range of cancer types. Aurora A expression in tumors is often associated with gene amplification, genetic instability, poor histologic differentiation, and poor prognosis. Aurora B is frequently expressed at high levels in a variety of tumors, often coincidently with aurora A, and expression level has also been associated with increased genetic instability and clinical outcome. Further, aurora kinase gene polymorphisms are associated with increased risk or early onset of cancer. The expression of aurora C in cancer is less well studied. In recent years, several small-molecule aurora kinase inhibitors have been developed that exhibit preclinical activity against a wide range of solid tumors. Preliminary clinical data from phase I trials have largely been consistent with cytostatic effects, with disease stabilization as the best response achieved in solid tumors. Objective responses have been noted in leukemia patients, although this might conceivably be due to inhibition of the Abl kinase. Current challenges include the optimization of drug administration, the identification of potential biomarkers of tumor sensitivity, and combination studies with cytotoxic drugs. Here, we summarize the most recent preclinical and clinical data and discuss new directions in the development of aurora kinase inhibitors as antineoplastic agents.

Regulation of Id1 expression by SRC: implications for targeting of the bone morphogenetic protein pathway in cancer

Deregulated activation of the Src tyrosine kinase and heightened Id1 expression are independent mediators of aggressive tumor biology. The present report implicates Src signaling as a critical regulator of Id1 gene expression. Microarray analyses showed that Id family genes were among the most highly down-regulated by incubation of A549 lung carcinoma cells with the small-molecule Src inhibitor AZD0530. Id1 transcript and protein levels were potently reduced in a dose-dependent manner concomitantly with the reduction of activated Src levels. These effects were conserved across a panel of lung, breast, prostate, and colon cancer cell lines and confirmed by the ability of PP2, Src siRNA, and Src-blocking peptides to suppress Id1 expression. PP2, AZD0530, and dominant-negative Src abrogated Id1 promoter activity, which was induced by constitutively active Src. The Src-responsive region of the Id1 promoter was mapped to a region 1,199 to 1,360 bps upstream of the translation start site and contained a Smad-binding element. Src was also required for bone morphogenetic protein-2 (BMP-2)-induced Id1 expression and promoter activity, was moderately activated by BMP-2, and complexed with Smad1/5. Conversely, Src inhibitors blocked Smad1/5 nuclear translocation and binding to the Src-responsive region of the Id1 promoter. Consistent with a role for Src and Id1 in cancer cell invasion, Src inhibitors and Id1 siRNA decreased cancer cell invasion, which was increased by Id1 overexpression. Taken together, these results reveal that Src positively interacts with the BMP-Smad-Id pathway and provide new ways for targeted inhibition of Id1.