Dottorato in FISIOPATOLOGIA ED IMAGING CARDIO-TORACO-VASCOLARE

Titolo della tesi: Angiogenesi tumorale e stress ossidativo nelle neoplasie neuroendocrine polmonari: possibili biomarcatori diagnostici, prognostici e terapeutici.

Objectives The neoplastic angiogenesis is an aberrant process associated with an heterogenous distribution of the oxygen through the tumor and subsequently oxidative stress. Since the neuroendocrine tumors (NET) are macroscopically characterized by a high vascular supply, our goal is to verify if angiogenic activity is more present and if the oxidative stress could have a preeminent role in the lung NET (well and poorly differentiated) compared with other neoplasms. Furthermore, we try to identify specific markers of angiogenesis and oxidative stress in these neoplasms. Methods From April 2010 to October 2021 84 patients were operated radically for typical (TC), atypical carcinoid (AC) and large cell neuroendocrine carcinoma (LCNEC). We analyzed angiogenic activity by tissue vascular endothelial growth factor A receptor (VEGFAR) expression and serum/tissue level of VEGFA and somatostatin type 2 receptor (SSTR2). Furthermore, we compared serum oxidative stress parameters such as soluble Nox2-derived peptide (sNOX2-dp) release, hydrogen peroxide (H2O2) production, H2O2 break-down activity (HBA) and endothelial dysfunction (NO). For the study, we considered a group of 20 patients operated for NET, a group of 20 patients operated for NSCLC and a group of 20 healthy non-operated patients (control group). Instead, the tissue assays of VEGFA and SSTR2 were done in a subgroup of 10 patients operated for NET and NSCLC respectively. Results The VEGFA-receptor/β-actin (A.U.) was higher in the NET compared with NSCLC (p<0.005). The serum level of VEGFA (pg/ml) was different between the groups considered (p<0.001). In particular, the NET group demonstrated a higher value (median 904.3 pg/ml, IQR 708.5; 1093.5) compared to NSCLC group (median 699.6 pg/ml, IQR 634.5; 807.5) and control group (median 335.7 pg/ml, IQR 241.1; 384.1). This difference reflects that recorded also at the tissue level (p<0.05) where the assay performed on a tissue neuroendocrine tumor sample showed a VEGFA value (median 809.7 pg/ml, IQR 730.7; 906) higher than NSCLC tumors (median 567.2 pg/ml, IQR 476.5; 717.4). There is no linear relationship between the serum and tissue level of VEGFA (r = 0.060, 95% CI, -0.392: 0.492). The SSTR2 (ng/mL) assay demonstrated differences between groups (p <0.001). The SSTR2 level was higher in the NET group (median 17.5 ng/mL, IQR 15.4; 25.6) than in the NSCLC group (median 10 ng/mL, IQR 6.8; 13.7) and the control group (median 3.1 ng/ml, IQR 1.5; 5.4). The difference between groups is also confirmed for the SSTR2 assay in tumor tissue (p <0.005). In the NET group the SSTR2 tissue level (median 17.5 ng/ml, IQR 14.9; 20.9) is higher than in the NSCLC group (median 9.5 ng/ml, IQR 7.2; 11.4). The oxidative stress was different between groups (p<0.001). The median sNOX2-dp (pg/ml) in the NET (45 pg/ml, IQR 35.8;47.8) was higher compared with NSCLC (31.2 pg/ml, IQR 26.9;38) and control group (31.2 pg/ml, IQR 24.6;42.2) respectively. The same can be said for H2O2 (μM, p< 0.001) where in the NET the median was higher (41.0 μM, IQR 33.4;44.8) compared with NSCLC (27.3 μM, IQR 22.7;36.0) and control group (10.3 μM, IQR 9.1;12.7). There is a moderate linear relationship between the serum sNox2-dp level and the serum H2O2 level (r = 0.54, 95% CI: 0.334; 0.699). The HBA inhibition activity (%) is different (p< 0.001) but, conversely, the NET showed a lower activity (32%, IQR 26;41) compared with NSCLC (41%, IQR 34;53) and control group (54%, IQR 47;62). There was a negative linear correlation between HBA and H2O2 (r= -0.60). Endothelial dysfunction evaluation (NO, μM) confirmed the difference (p< 0.001) between groups. The median in the NET was lower (9.9 μM, IQR 9.5;11.6) compared with NSCLC (13.5 μM, IQR 10.8;19.5) and control group (25.9 μM, IQR 20.2;29.1). Conclusions If further studies confirmed the role of the angiogenic activity and oxidative stress level as shown in the lung NET, they would give new perspectives especially in new drug treatments.