Dyspnea is a frequent, devastating, and poorly understood symptom of advanced lung cancer. In our cohort, among 519 patients who underwent a computed tomography scan for the diagnosis of lung cancer, 250 had a mean pulmonary artery diameter of >28 mm, indicating pulmonary hypertension (PH). In human lung cancer tissue, we consistently observed increased vascular remodeling and perivascular inflammatory cell accumulation (macrophages/lymphocytes). Vascular remodeling, PH, and perivascular inflammatory cell accumulation were mimicked in three mouse models of lung cancer (LLC1, , and). In contrast, immunodeficient xenograft and dominant-negative IKK2 mutant triple transgenic () mice did not develop PH. Coculturing human lung cancer cells with macrophages and lymphocytes strongly up-regulated cytokine release, provoking enhanced migration, apoptosis resistance, and phosphodiesterase 5 (PDE5)-mediated up-regulation of human lung vascular cells, which are typical features of PH. The PDE5 inhibitor sildenafil largely suppressed PH in the LLC1 model. We conclude that lung cancer-associated PH represents a distinct PH category; targeting inflammation in the microenvironment and PDE5 offers a potential therapeutic option.

Cancer stem cells (CSCs) are thought to be responsible for tumor initiation and recurrence after chemotherapy. Targeting CSCs and non-CSCs with specific compounds may be an effective approach to reduce lung cancer growth and metastasis. The aim of this study was to investigate the effect of salinomycin, a selective inhibitor of CSCs, with or without combination with paclitaxel, in a metastatic model. To evaluate the effect of these drugs in metastasis and tumor microenvironment we took advantage of the immunocompetent and highly metastatic LLC mouse model. Aldefluor assays were used to analyze the ALDH+/− populations in murine LLC and human H460 and H1299 lung cancer cells. Salinomycin reduced the proportion of ALDH+ CSCs in LLC cells, whereas paclitaxel increased such population. The same effect was observed for the H460 and H1299 cell lines. Salinomycin reduced the tumorsphere formation capacity of LLC by more than 7-fold, but paclitaxel showed no effect. In in vivo experiments, paclitaxel reduced primary tumor volume but increased the number of metastatic nodules (p<0.05), whereas salinomycin had no effect on primary tumors but reduced lung metastasis (p<0.05). Combination of both drugs did not improve the effect of single therapies. ALDH1A1, SOX2, CXCR4 and SDF-1 mRNA levels were higher in metastatic lesions than in primary tumors, and were significantly elevated in both locations by paclitaxel treatment. On the contrary, such levels were reduced (or in some cases did not change) when mice were administered with salinomycin. The number of F4/80+ and CD11b+ cells was also reduced upon administration of both drugs, but particularly in metastasis. These results show that salinomycin targets ALDH+ lung CSCs, which has important therapeutic effects in vivo by reducing metastatic lesions. In contrast, paclitaxel (although reducing primary tumor growth) promotes the selection of ALDH+ cells that likely modify the lung microenvironment to foster metastasis.

Considering the recent advances in understanding lung tumor stroma, lung cancer progression could be effectively hampered by combining cytotoxic strategies with therapies that target the TME. However, more preclinical and clinical research is needed to prove the efficacy of this strategy for treating NSCLC.

Although progenitor cells of the conducting airway have been spatially localized and some insights have been gained regarding their molecular phenotype, relatively little is known about the mechanisms regulating their maintenance, activation, and differentiation. This study investigates the potential roles of E-cadherin in mouse Clara cells, as these cells were shown to represent the progenitor/stem cells of the conducting airways and have been implicated as the cell of origin of human non-small cell lung cancer. Postnatal inactivation of E-cadherin affected Clara cell differentiation and compromised airway regeneration under injury conditions. In steady-state adult lung, overexpression of the dominant negative E-cadherin led to an expansion of the bronchiolar stem cells and decreased differentiation concomitant with canonical Wnt signaling activation. Expansion of the bronchiolar stem cell pool was associated with an incessant proliferation of neuroepithelial body.associated Clara cells that ultimately gave rise to bronchiolar hyperplasia. Despite progressive hyperplasia, only a minority of the mice developed pulmonary solid tumors, suggesting that the loss of E-cadherin function leads to tumor formation when additional mutations are sustained. The present study reveals that E-cadherin plays a critical role in the regulation of proliferation and homeostasis of the epithelial cells lining the conducting airways.