Stem cells for lung cancer?

Stem cells are believed to be crucial players in tumor development. There is much interest in identifying those compartments that harbor stem cells involved in lung cancer, given the high incidence and recurrence rate of this disease. In this issue of Cell, Kim and colleagues describe a niche in the bronchioalveolar duct junction of adult mouse lung that harbors stem cells from which adenocarcinomas are likely to arise. They enriched, propagated, and differentiated these stem cells in vitro and found that they were activated by the oncogenic protein K-ras. This study provides exciting insights into how the stem cell compartment operates during both normal lung-tissue homeostasis and the development of lung cancer. The new work offers perspectives on possible therapeutic interventions to combat lung cancer.     

Radiotherapy in lung cancer. Mandatory or optional?

The purpose of the paper is to outline the current treatment strategies in lung cancer focusing on the possibile role of radiotherapy. METHOD: It defines the place of radiotherapy at the main histological types and stadiums proposing indications according to evidence based medicine. CONCLUSIONS: Radiotherapy is mandatory in non-operated NSCLC st. I-II in perioperative or palliative management of superior sulcus tumours; in the combined modality treatment of limited SCLC and in postoperative adjustment of resected single brain metastasis of lung cancer. It is optional after NSCLC segmentectomy; in palliation or postoperative adjuvation of NSCLC st. III Radiotherapy can be chosen as a part of best supportive care at NSCLC st. IV extensive SCLC and in case of multiple brain or localised lytic bone metastases.     

Passive smoking and lung cancer: a publication bias?

To assess the likelihood of publication bias in a recent review of the effect of passive smoking on lung cancer the evidence from the reviewed papers was visualised on a “funnel” plot. In such a plot if the relative risks from various studies are plotted according to sample size they should scatter round some underlying true value, the scatter being greatest where the studies have the lowest statistical power—thus showing a “funnel” pattern. If there is publication bias and studies with non-significant results are not being published there should be a “gap” in the plot. The logarithm of the relative risks was plotted against the standard error of the logarithm of the relative risk (which was used instead of sample size as a measure of statistical uncertainty). The resulting plot was compatible with a publication bias but only in studies on men.Further studies of passive smoking and lung cancer in men seem to be warranted.     

Does hydatid disease have protective effects against lung cancer?

We hypothesized that solid tumors rarely occur in patients with hydatid disease. We obtained the serum of 14 patients diagnosed with hydatid disease, the serum of 10 patients who did not have a history of hydatid disease, and the hydatid cyst fluid from six patients. These sera and fluid samples were added at different concentrations to NCI-H209/An1 human lung small cell carcinoma cells and L929 mouse fibroblasts as a control group. Sera of patients with hydatid diseases had cytotoxic effects on NCI-H209/An1 cells, but they did not have cytotoxic effects on fibroblast cells. Sera from healthy subjects did not have a cytotoxic effect on the tumor cell line or control fibroblasts. Cyst fluid, also, did not have toxic effects on the NCI-H209/An1 cell line, but was toxic to fibroblasts up to a 1:32 dilution. Sera from patients with hydatid disease had cytotoxic effects on human small cell lung cancer cells in vitro.     

Wnt/β-catenin signaling regulates cancer stem cells in lung cancer A549 cells

Wnt/β-catenin signaling plays an important role not only in cancer, but also in cancer stem cells. In this study, we found that β-catenin and OCT-4 was highly expressed in cisplatin (DDP) selected A549 cells. Stimulating A549 cells with lithium chloride (LiCl) resulted in accumulation of β-catenin and up-regulation of a typical Wnt target gene cyclin D1. This stimulation also significantly enhanced proliferation, clone formation, migration and drug resistance abilities in A549 cells. Moreover, the up-regulation of OCT-4, a stem cell marker, was observed through real-time PCR and Western blotting. In a reverse approach, we inhibited Wnt signaling by knocking down the expression of β-catenin using RNA interference technology. This inhibition resulted in down-regulation of the Wnt target gene cyclin D1 as well as the proliferation, clone formation, migration and drug resistance abilities. Meanwhile, the expression of OCT-4 was reduced after the inhibition of Wnt/β-catenin signaling. Taken together, our study provides strong evidence that canonical Wnt signaling plays an important role in lung cancer stem cell properties, and it also regulates OCT-4, a lung cancer stem cell marker.     

The expression of core fucosylated E-cadherin in cancer cells and lung cancer patients： prognostic implications

It is well documented that the glycosylation of E-cadherin is correlated with cancer metastasis, but whether E-cadherin could be core fucosylated remains largely unknown. We found that E-cadherin was core fucosylated in highly metastatic lung cancer cells while absent in lowly metastatic lung cancer cells. Sinceα-1,6 Fucosyltransferase (α-1,6 FucT) is known to catalyze the reaction of core fucosylation, we investigated the biological function of core fucosylation on E-cadherin by α-1,6 FucT targeted RNAi and transfecting α-1,6 FucT expression vector. As a result, calcium dependent cell-cell adhesion mediated by E-cadherin was strengthened with the reduction of core fucosylation on E-cadherin after RNAi and was weakened with the elevated core fucosylation on E-cadherin after α-1,6 FucT over expression. Our data indicated that α-1,6 FucT could regulate E-cadherin mediated cell adhesion and thus play an important role in cancer development and progression. Computermodeling showed that core fucosylation on E-cadherin could significantly impair three-dimensional conformation of N-glycan on E-cadherin and produce conformational asymmetry so as to suppress the function of E-cadherin. Furthermore, the relationship between the expression of core fucosylated E-cadherin and clinicopathological background of lung cancer patients was explored in lung cancer tissue of patients. It turns out to demonstrate that core fucosylated E-cadherin could serve as a promising prognostic indicator for lung cancer patients.     

Targeting PKCε by miR-143 regulates cell apoptosis in lung cancer

Non-small cell lung cancer (NSCLC) is one of the most common causes for lung cancer and cancer-related death. The imbalance between cell proliferation and apoptosis was suggested to play an important role in cancer pathogenesis and PKCε is one of the widely recognized targets. Here, we demonstrate that miR-143 is aberrantly downregulated in NSCLC tissue and negatively correlates with expression of PKCε. We show that miR-143 specifically targets the 3′-UTR of PKCε and regulates its expression. Treatment with miR-143 inhibitor mimics cell proliferation and apoptosis imbalance in NSCLC, while inhibition of PKCε can reverse it. Our findings suggest that targeting PKCε overexpression in NSCLC should be beneficial for lung cancer therapy.     

Identification of EGFR kinase domain mutations among lung cancer patients in China： implication for targeted cancer therapy

Lung cancer is one of the leading causes of death with one of the lowest survival rates. However, a subset of lung cancer patients who are of Asian origin and carry somatic mutations in epidermal growth factor receptor or EGFR have responded remarkable well to two tyrosine kinase inhibitors, gefitinib and erlotinib. While EGFR mutation profiles havebeen reported from Japan, South Korea, and Taiwan, there is no such report from mainland of China where the largest pool of patients reside. In this report, we identified ten somatic mutations from a total of 41 lung cancer patients in China. Among them, seven mutations were found in 17 adenocarcinomas. In contrast to previous reports, eight of these mutations are deletions in exon 19 and two of these deletions are homozygous. These results suggest that a large portion of Chinese adenocarcinoma patients could benefit from gefitinib or erlotinib. This unique mutation profile provides a rationale to develop the next generation of EGFR inhibitors more suitable for the Chinese population.     

Clinical significance of serum transforming growth factor-β1 in lung cancer

Background: Transforming growth factor-β1 (TGF-β1) plays a critical role in human cancer development. Present study aimed to explore the clinical significance of serum TGF-β1 levels in patients with lung cancer and analyze the relationship between TGF-β1 and existing tumor markers for lung cancer. Methods: Serum was collected from 118 patients with lung cancer and 40 healthy volunteers. Serum TGF-β1 levels were measured by enzyme-linked immunosorbent assay (ELISA), and the association with various clinical characteristics was analyzed. The diagnostic value of TGF-β1 was assessed alone and in combination with existing tumor markers for lung cancer. Results: Serum TGF-β1 levels were significantly higher in patients with lung cancer compared to healthy volunteers [0.6 × 10⁵ (0.4 × 10⁵, 0.9 × 10⁵) pg/ml vs 0.5 × 10⁵ (0.3 × 10⁵, 0.7 × 10⁵) pg/ml, P = 0.040]. Although there was a positive correlation between serum TGF-β1 levels and advanced stages, the significant difference was not found between early stages and advanced stages (P = 0.116). The ability of serum TGF-β1 to discriminate lung cancer at a cutoff value of 79,168 pg/ml exhibited sensitivity of 30.6% and specificity of 97.5%. Serum TGF-β1 levels were correlated to cytokeratin fragment 21-1 (CYFRA21-1; R = 0.308, P = 0.020) and neuron-specific enolase (NSE; R = 0.558, P = 0.003). The diagnostic accuracy rates for the existing lung-tumor markers, as SCC, CYFRA21-1, and NSE, were increased from 20.0%, 34.6%, and 45.9% to 48.9%, 51.7%, and 54.5%, respectively by the inclusion of serum TGF-β1 levels. Conclusion: Quantification of serum TGF-β1 levels by ELISA may provide a novel complementary tool for the clinical diagnosis of lung cancer.     

Estrogen receptor β signaling regulates the progression of Chinese non-small cell lung cancer

Prospective studies have found that the risk of non-small cell lung cancer (NSCLC) has close relationship with estrogen. The effects of estrogens are mediated via two estrogen receptor (ER) isoforms, that is, ER alpha (ERα) and ER beta (ERβ). ERα in NSCLC has been evaluated mostly by immunohistochemistry. However, our previous study showed that ERβ was also highly expressed in Chinese NSCLC. But the roles of ERβ in Chinese NSCLC have not been clarified as yet. So in the present study, two Chinese lung adenocarcinoma cell lines, SPC-A1 and LTEP-a2, were used and the role of ERβ in lung tumorigenesis was focused to be investigated by in vitro and in vivo experiments. The results showed that over-expressed ERβ can promote the development of NSCLC, while siRNAs targeting ERβ gene can inhibit growth of NSCLC cells and induce apoptosis of these cells via mitochondrial depolarization and caspase-3 activation. These results indicated that ERβ plays an important role in development of Chinese NSCLC. This suggests that ERβ deactivation or down-regulation may possess potential therapeutic utility for the treatment of lung cancer.     

Activation of PPARγ in myeloid cells promotes lung cancer progression and metastasis

Activation of peroxisome proliferator-activated receptor-γ (PPARγ) inhibits growth of cancer cells including non-small cell lung cancer (NSCLC). Clinically, use of thiazolidinediones, which are pharmacological activators of PPARγ is associated with a lower risk of developing lung cancer. However, the role of this pathway in lung cancer metastasis has not been examined well. The systemic effect of pioglitazone was examined in two models of lung cancer metastasis in immune-competent mice. In an orthotopic model, murine lung cancer cells implanted into the lungs of syngeneic mice metastasized to the liver and brain. As a second model, cancer cells injected subcutaneously metastasized to the lung. In both models systemic administration of pioglitazone increased the rate of metastasis. Examination of tissues from the orthotopic model demonstrated increased numbers of arginase I-positive macrophages in tumors from pioglitazone-treated animals. In co-culture experiments of cancer cells with bone marrow-derived macrophages, pioglitazone promoted arginase I expression in macrophages and this was dependent on the expression of PPARγ in the macrophages. To assess the contribution of PPARγ in macrophages to cancer progression, experiments were performed in bone marrow-transplanted animals receiving bone marrow from Lys-M-Cre+/PPARγ(flox/flox) mice, in which PPARγ is deleted specifically in myeloid cells (PPARγ-Mac(neg)), or control PPARγ(flox/flox) mice. In both models, mice receiving PPARγ-Mac(neg) bone marrow had a marked decrease in secondary tumors which was not significantly altered by treatment with pioglitazone. This was associated with decreased numbers of arginase I-positive cells in the lung. These data support a model in which activation of PPARγ may have opposing effects on tumor progression, with anti-tumorigenic effects on cancer cells, but pro-tumorigenic effects on cells of the microenvironment, specifically myeloid cells.     

Down-regulation of β3-integrin inhibits bone metastasis of small cell lung cancer

Bone is one of the most frequent targets of small cell lung cancer (SCLC) metastasis, but the molecular mechanism remains unclear. β3-integrin plays an important role in invasion of various kinds of tumors. Yet, its role in bone-metastasis of SCLC is still unknown. In this study, we first examined the expression of β3-integrin in SBC-5 and SBC-3 cells by real-time PCR, western blot and immunofluorescence. We found that, compared to none bone-metastatic SBC-3 cells, β3-integrin was highly expressed in SBC-5 cells, a specific bone-metastatic SCLC cells line characterized in our previous study. We next constructed β3-integrin siRNA and transfected SBC-5 cell line, and found that β3-integrin siRNA significantly down-regulated the β3-integrin mRNA level and protein expression in SBC-5 cell line. We further found that inhibition of β3-integrin significantly reduced tumor cell proliferation and induced apoptosis. In addition, the β3-integrin down-regulated cells presented significant decrease in cell adhesion, migration and invasion activity. Our results suggest the β3-integrin has an essential effect on tumor cell proliferation and progression, and may be a potential therapeutic target for the prevention of skeletal metastases of lung cancer.     

Thromboxane synthase suppression induces lung cancer cell apoptosis via inhibiting NF-κB

Accumulating evidence shows that the inhibition of thromboxane synthase (TXS) induced apoptosis in cancer cells. TXS inhibitor 1-Benzylimidzole (1-BI) can trigger apoptosis in lung cancer cells but the mechanism is not fully defined. In this study, lung cancer cells were treated with 1-BI. In this study, the level of reactive oxygen species (ROS) was measured and NF-κB activity was determined in human lung cancer cells. The roles of ROS and NF-κB in 1-BI-mediated cell death were analyzed. The results showed that 1-BI induced ROS generation but decreased the activity of NF-κB by reducing phosphorylated IκBα (p-IκBα) and inhibiting the translocation of p65 into the nucleus. In contrast to 1-BI, antioxidant N-acetyl cysteine (NAC) stimulated cell proliferation and significantly protected the cells from 1-BI-mediated cell death by neutralizing ROS. Collectively, apoptosis induced by 1-BI is associated with the over-production of ROS and the reduction of NF-κB. Antioxidants can significantly block the inhibitory effect of 1-BI.     

Intrapleural instillation of interferon γ in patients with malignant pleurisy due to lung cancer

 The effect of intrapleural instillation of recombinant human interferon γ (IFNγ) at increasing doses of (1–12) × 10⁶ U was examined in six patients with cytologically positive pleural effusion due to lung cancer. Intrapleural instillation was repeated up to three times. Clinically, no reaccumulation of pleural effusion was observed in one patient and disappearance of lung cancer cells from the pleural effusion was seen in two other patients. No severe side-effects were observed. Considerable levels of IFNγ remained in the pleural effusion as well as in patients’ serum up to 7 days after instillation of 2 × 10⁶ U and higher doses. The total cell number showed a transient decrease on day 1 of therapy. Levels of pro-inflammatory cytokines, such as tumor necrosis factor α, interleukin(IL)-1β and IL-6, in the pleural effusion remained almost stable after IFNγ instillation. On the other hand, intrapleural IL-1 receptor antagonist levels were remarkably elevated by the instillation of IFNγ. IL-2- and IL-12-inducible killer activity of pleural mononuclear cells tended to increase slightly. Despite the inability of IFNγ to control pleural effusion in this treatment schedule, IFNγ instilled by an intrapleural route had a potential local antitumor activity. Moreover, since IFNγ persists in pleural effusions for a long time after a single instillation, such a therapy in combination with other fibrogenic biological response modifiers can be promising. Received: 28 February 1997 / Accepted: 23 July 1997     

Chidamide alleviates TGF-β-induced epithelial–mesenchymal transition in lung cancer cell lines

Transforming growth factor-β (TGF-β)-induced epithelial–mesenchymal transition is a critical process in the initiation of metastasis of various types of cancer. Chidamide is a class I histone deacetylase inhibitor with anti-tumor activity. This study investigated the effects of chidamide on TGF-β-mediated suppression of E-cadherin expression in adenocarcinomic lung epithelial cells and the molecular mechanisms involved in these effects. Western blot analysis, confocal microscopy, Quantitative methyl-specific PCR and bisulfite sequencing were used to evaluate the effects of different treatments on chidamide ameliorating TGF-β induced-E-cadherin loss. H3 acetylation binding to the promoter of E-cadherin was detected by chromatin immunoprecipitations (CHIP). We found that chidamide reduced the level of lung cancer cell migration observed using a Boyden chamber assay (as an indicator of metastatic potential). Chidamide inhibited TGF-β-induced SMAD2 phosphorylation and attenuated TGF-β-induced loss of E-cadherin expression in lung cancer cells by Western blotting and confocal microscopy, respectively. Quantitative methyl-specific PCR and bisulfite sequencing revealed that TGF-β-enhanced E-cadherin promoter methylation was ameliorated in cells treated with chidamide. We demonstrated that histone H3 deacetylation within the E-cadherin promoter was required for TGF-β-induced E-cadherin loss; cell treatment with chidamide increased the H3 acetylation detected by CHIP. Taken together, our results demonstrate that TGF-β suppressed E-cadherin expression by regulating promoter methylation and histone H3 acetylation. Chidamide significantly enhanced E-cadherin expression in TGF-β-treated cells and inhibited lung cancer cell migration. These findings indicate that chidamide has a potential therapeutic use due to its capacity to prevent cancer cell metastasis.     

Does hepatocyte growth factor/c-Met signal play synergetic role in lung cancer?

There is growing evidence that the signal pathway between hepatocyte growth factor (HGF) and its receptor c-Met plays an important role in the development of lung cancer, although the specificity of such role is to be clarified. It seems clear that the HGF/c-Met signal contributes to the metastasis of cancer cells to the lung by stimulating the hyperproduction and overactivation of cytokines and enzymes, e.g. HGF, vascular endothelial growth factor and matrix metalloproteases. The HGF/c-Met signal may act as the candidate responsible for the development of epidermal growth factor receptor (EGFR) kinase inhibitor resistance. Experimental evidence showed that the combination of both EGFR and c-Met inhibitors had synergetic or additive therapeutic effects on lung cancer. Although the mechanism of interaction between HGF/c-Met and transforming growth factor-a/EGFR remains unclear, the cross-talk and balance between those two signal pathways are critical and necessary in the development of new therapies for lung cancer.