Ratios between VEGF ligands and receptors in tumor and stroma have impact on the outcome in resectable NSCLC

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Background: In tumor angiogenesis there is a complex interplay between endothelial, stromal and tumor cells. Some key regulators of this process are the members of the vascular endothelial growth factor (VEGF) family of ligands and receptors and the neuropilins (NRP). This study analyzes the correlations between the expression of these angiogenic factors in tumor cells and tumor stroma, and their prognostic role in tissue samples from resected non-small cell lung cancer (NSCLC) patients. Methods: Representative tumor and stroma areas from FFPE tissue samples of 125 early-stage NSCLC patients were carefully micro-dissected. RNA isolated from the samples was retrotranscripted and preamplified. RTqPCR was performed using hydrolysis probes (TaqMan, Applied Biosystems) and relative quantification was calculated using GAPDH and CDKN1B as endogenous controls. Results were normalized against a human cDNA (Clontech) as a reference. All statistical analyses were considered significant at p<0.05. Results: Paired Wilcoxon test revealed differences between tumor and stroma gene expression for VEGFB (p<0.0001), VEGFC (p<0.0001), VEGFR-1 (p<0.0001), VEGFR-2 (p=0.020), VEGFR-3 (p< 0.0001), NRP-1 (p=0.001) and NRP-2 (p< 0.0001). Survival analyses showed that those patients with higher levels of the Ratio Stromal-VEGFA/ Tumoral-VEGFR-2 had worse time to progression (TTP) (median 26.23 months vs NR, p=0.013) and overall survival (OS) (median 29.50 months vs NR, p=0.001). Similarly, those patients with higher levels of the Ratio Stromal-VEGFC/Tumoral-VEGFR-3 had worse TTP (median 23.30 vs 70.53 months, p=0.015) and OS (median 37.20 months vs NR, p=0.023). Conclusions: Our results show significant differences in the expression of VEGF family members between tumor and stromal cells. This may indicate the importance of the tumor-stroma interaction when trying to understand the angiogenic process. Furthermore, the combination of the ligands expression in stroma and their receptors in tumor may have a prognostic value in NSCLC patients. Supported by grants PS09-01149 and RD06/0020/1024 from ISCIII.

Prognostic value of “angiogenic” risk score in early-stage NSCLC

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Background: Angiogenesis is a key mechanism in tumor growth and dissemination mainly regulated by VEGF family members. We analyze the expression of 11 angiogenic genes in a cohort of resectable NSCLC patients and correlate them with clinico-pathological variables and prognosis. Methods: RNA was obtained from tumor and normal lung specimens from 175 NSCLC patients. RT-PCR was performed to assess the expression of HIF1-A, PIGF, VEGFA, VEGFB, VEGFC, VEGFD, VEGFR1, VEGFR2, VEGFR3, NRP1 and NRP2. Relative expression was normalized by an endogenous gene (GUS) using the Pfaffl formulae. Differences were considered statistically significant at p<0.05. Results: We found that tumor samples had a significant higher expression of PIGF and lower expression of VEGFD, VEGFR2, and VEGFR3 compared with normal tissue (2.76X, 0.035X, 0.417X and 0.426X, respectively). The group of patients with higher expression levels of VEGFA or PlGF had a significantly reduced TTP (p=0.024 and p=0.027, respectively) and OS (p=0.055 and p=0.048, respectively) whereas those patients with values of VEGFB or VEGFD below the median had reduced TTP (p=0.020 and p=0.135, respectively) and OS (p=0.003 and p=0.089, respectively). The multivariate Cox regression analysis revealed that VEGFA, VEGFB and PlGF were independent prognostic markers for TTP and OS and based on these results we generated an “angiogenic” risk score model. TTP and OS were significantly different among the low, medium and high risk score patients (Table). Conclusions: VEGF family members are master control genes of the angiogenic process and have a crucial role in the prognostic of the disease. We found differences in the expression of four genes between tumor and normal lung samples. An “angiogenic” risk score (based on the expression of PlGF, VEGF-A and VEGF-B) significantly predicts OS and TTP in our cohort of early-stage NSCLC patients. Validation in an independent cohort is needed. Supported by grants PS09-01149 and RD06/0020/1024 from ISCIII. [Table: see text]

miRNA profiling in resectable NSCLC by multiplex next-generation sequencing

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Background: Early-stage NSCLC has a relapse rate around 40% within 5 years. With the advent of microRNA (miRNA), which seems to regulate many genes critical for tumorigenesis, there is a growing interest in the characterization of miRNAome in NSCLC specimens and to correlate them with prognosis. Next generation sequencing is a useful tool to study the miRNA content of solid tumors. Here, we applied high-throughput SOLiD transcriptome sequencing to study miRNAs expression in a cohort of early-stage NSCLC patients (tumor vs normal lung). Methods: RNA was isolated from frozen lung specimens (tumor and normal lung) from resectable NSCLC patients (n=35). Samples with a RIN ≥ 7 were analyzed and enriched in the miRNA fraction. miRNAs were sequencing using a bar-code multiplex SOLiD protocol. Data normalization was carried out by rescaling all data according to their counts. Readings were mapped against mature and no-mature miRNAs using miRBase. Statistical analysis was performed with CLCbio software and considered significant when p-adj<0.005. Results: Using the SOLiD high throughput sequencing, we performed a systemic miRNA expression profiling analysis of paired samples (tumor vs normal lung). A total of 1268 miRNAs (mature and no-mature) have been detected in at least one sample. The differential expression between normal and tumor samples shown that 6 miRNAs (miR-193b, miR-182, miR-96, miR-148a, miR-299, miR-590) were upregulated and 7 (miR-145, miR-133a, miR-218, miR-125a, miR-30a, miR-126 and miR-139) were down-regulated significantly in tumor samples compared with normal lung tissues. We are performing studies using qRT-PCR in an independent cohort to further validate these findings. Conclusions: The deep sequencing technology used for differential miRNA expression is useful and novel. The use of barcoding allows multiplexing and lowers cost per sample. Several miRNAs were differentially expressed between tumor and normal tissue, but this point needs to be further validated in an independent cohort. Supported by grants TRA09-0132 (MICINN) and RD06/0020/1024 (ISCIII).

Prognostic role of FOXP3/CD4 ratio in resectable NSCLC

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Background: Tregs play a critical role in immune tolerance to tumor cells and have been related to prognosis. The aim of this study was to determine the expression of Tregs makers genes by RT-PCR and to correlate them with clinico-pathological and prognostic variables in NSCLC. Methods: RNA was isolated from frozen lung specimens (tumor and normal lung) from resectable NSCLC patients (n=175). RT-PCR was performed to analyze the expression of: CD4, CD8A, CTLA-4, FoxP3, IL-10, CD25, CD127 and TGFβ-1. Relative expression was normalized by an endogenous gene (GUSB) using the Pfaffl formulae. Statistical analyses were considered significant at p<0.05. Results: Tumor samples had significantly lower expression of CD127 (x0.45) and a tendency toward higher expression of CD25 (x1.81), FoxP3 (x1.57) and CTLA-4 (x1.53) compared to normal lung tissues, reflecting a Treg phenotype infiltrating the tumor. Survival analyses revealed that patients with higher FoxP3 expression had reduced OS (median 29.8 vs 67 months, p= 0.026). We also found that those patients with high levels FoxP3/CD4 ratio had worse TTP and OS (median 22.1 months vs NR, p= 0.021 and 29.8 vs NR months, p=0.003, respectively). A multivariable Cox regression model for TTP and OS was built using variables that were found significant in the univariate analysis (nodal involvement, histology, tumor size, PS, and FoxP3/CD4 ratio). This analysis revealed that FoxP3/CD4 ratio was an independent prognostic marker for both TTP and OS (see table). Conclusions: FoxP3 is a transcription factor necessary and sufficient for induction of the immunosuppressive functions in Tregs. In concordance, our results indicate that higher levels of FoxP3/CD4 ratio in tumor samples is a poor prognostic markers for TTP and OS. Furthermore, the multivariable COX regression analysis showed that FoxP3/CD4 ratio is an independent prognostic marker. Therefore, this ratio could be used as a new biomarker of prognosis in resectable NSCLC. Supported by grants PS09-01149 and RD06/0020/1024 from ISCIII. [Table: see text]

Soluble vascular endothelial growth factor receptor 2 (VEGFR2): New biomarker in advanced non-small cell lung cancer (NSCLC)?

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Background: An increase in VEGF expression in tumour or some blood compartments (i.e. serum or plasma) has been found in solid tumours of various origins. Several studies have suggested that ligands and receptors of the VEGFs/VEGFR system play an important role in tumour growth and is associated with metastasis and poor prognosis. The aim of our study was to investigate the usefulness of plasmatic VEGFR2 quantification as a new biomarker in advanced NSCLC. Methods: We studied 106 healthy controls (c) and 467 advanced NSCLC patients (p) (stage IIIB and IV) treated with cisplatin and docetaxel. Blood samples were collected before chemotherapy and the plasmatic levels of the VEGFR2 were determined by ELISA. Results: In the NSCLC group, the median age was 59.9, range (31–80); 82% were males. The histological subtypes were: 31.4% squamous, 49.8% adenocarcinoma, 15.3% large cell and undifferentiated and 3.5% other. There was a significant difference in the plasmatic levels of VEGFR2 between c and p (mean± SEM): 6318±152 ng/ml and 8141± 119 ng/ml, respectively (p<0.0001). On the other hand, we found no statistical differences according to sex, histology, or stage. The area under the ROC curve was 0.743 indicating that VEGFR2 is an adequate biomarker for the discrimination between c and p. Dividing the cohort in two subgroups according to VEGFR2 levels: high (>9473,9 ng/ml) and low (≤ 9473,9 ng/ml), we found significant difference in terms of Time to Progression (TTP). Patients with higher levels of VEGFR2 had a median TTP of 204 days whereas in the group with lower expression the median was 164 days, (p= 0.039). Conclusions: In advanced NSCLC, we found higher levels of soluble VEGFR2 in p than in c. There was a correlation between higher expressions of soluble VEGFR2 with better prognosis, in terms of TTP, therefore a more thorough understanding in the role of the plasmatic quantification of this angiogenic receptor in advanced NSCLC p seems to be an important task.

No significant financial relationships to disclose.

Expression of angiogenic genes in resectable non-small cell lung cancer (NSCLC)

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Background: NSCLC is a major cause of cancer-related death worldwide. The prognosis for lung cancer patients is poor with 5-years survival rates being less than 15%. It is known that angiogenesis is an essential event for solid tumour growth. Vascular endothelial growth factor (VEGF) family of ligand and receptors (VEGFR) are described as powerful angiogenic factors. VEGF belongs to a protein family, within which Placental growth factor (PlGF) is a member, they bound to their receptors at the membrane levels, gathering a cascade of intracellular events. In this study, we examine the expression of angiogenic genes in NSCLC samples correlating the expression of these genes between them and with clinicopathological variables. Methods: We performed real-time quantitative polymerase chain reaction (RT-qPCR) to assess the expression of VEGF, PlGF, VEGFR1 and VEGFR2 in frozen lung cancer specimens from untreated NSCLC patients who had undergone surgical resection (n=21). For this purpose, RNA was extracted and RTqPCR was performed using TaqMan® probes. Relative quantification was calculated by Pfaffl formulae, using an endogenous gene for normalization. We correlate the expression of the angiogenic genes between them and with other biologic variables. Statistical analysis were done using the SPSS 13.0 software. Results: Our results show that tumor samples have higher expression of PlGF than normal tissue. The expression of PlGF and VEGF correlates with the expression of their receptors in the group of samples analyzed. The expression of VEGFR1 and VEGFR2 was also significant correlated. We found a significant correlation between the levels of expression of PlGF and the tumor size (p= 0.023, Spearman's test), whereas no relation was found between the expression of the genes and the histology or stage of disease. Conclusions: Our results reveal that, in NSCLC, PlGF mRNA is higher in tumor than in normal tissue and is positively correlated with the tumor size and with the expression of angiogenic receptors. Theses finding could indicate that PlGF have some role in lung cancer progression and may be a promising new biomarker in NSCLC, but still more investigations are necessary with a larger number of samples. Supported by Instituto de Salud Carlos III (Fondo de Investigación Sanitario Grant).

No significant financial relationships to disclose.