STAT3: Versatile Functions in Non-Small Cell Lung Cancer

A Prognostic Role for Circulating microRNAs Involved in Macrophage Polarization in Advanced Non-Small Cell Lung Cancer

Circulating microRNAs (miRNAs) are key regulators of the crosstalk between tumor cells and immune response. In the present study, miRNAs (let-7c, miR-26a, miR-30d, miR-98, miR-195, miR-202) reported to be involved in the polarization of macrophages were examined for associations with the outcomes of non-small cell lung cancer (NSCLC) patients (N = 125) treated with first-line platinum-based chemotherapy. RT-qPCR was used to analyze miRNA expression levels in the plasma of patients prior to treatment. In our results, disease progression was correlated with high miR-202 expression (HR: 2.335; p = 0.040). Additionally, high miR-202 expression was characterized as an independent prognostic factor for shorter progression-free survival (PFS, HR: 1.564; p = 0.021) and overall survival (OS, HR: 1.558; p = 0.024). Moreover, high miR-202 independently predicted shorter OS (HR: 1.989; p = 0.008) in the non-squamous (non-SqCC) subgroup, and high miR-26a was correlated with shorter OS in the squamous (SqCC) subgroup (10.07 vs. 13.53 months, p = 0.033). The results of the present study propose that the expression levels of circulating miRNAs involved in macrophage polarization are correlated with survival measures in NSCLC patients, and their role as potential biomarkers merits further investigation.

Alkaloid Extract of Moringa oleifera Lam. Exerts Antitumor Activity in Human Non-Small-Cell Lung Cancer via Modulation of the JAK2/STAT3 Signaling Pathway

Lung cancer is one of the most common malignant tumors diagnosed worldwide. Moringa oleifera Lam. is a valuable medicinal plant native to India and Pakistan. However, the antilung cancer activity of M. oleifera alkaloid extract (MOAE) is unknown. The present study aimed to evaluate the regulatory effect of MOAE on A549 cells by examination of the proliferation, apoptosis, cell cycle, and migration of cells and to elucidate the possible mechanism of action of MOAE. We tested five types of cancer cells and four types of lung cancer cells and found MOAE exerted the strongest growth inhibitory effect against A549 cells but had low toxicity to GES-1 cells (human gastric mucosal epithelial cells). Simultaneously, MOAE induced apoptosis and increased the expression of the apoptosis-related proteins caspase-3 and caspase-9 in A549 cells. Furthermore, MOAE induced cell cycle arrest in the S phase through a decrease in the expression of the proteins cyclin D1 and cyclin E and an increase in the expression of the protein p21. MOAE also inhibited the migratory ability of A549 cells and decreased the expression of the migration-related proteins, matrix metalloproteinase (MMP) 2 and MMP9. In addition, the phosphorylation level of JAK2 and STAT3 proteins was decreased in MOAE-treated A549 cells. Furthermore, AZD1480 (a JAK inhibitor) and MOAE inhibited the proliferation and migration of A549 cells and induced cell apoptosis, and the effects of MOAE and AZD1480 were not additive. These results indicated that MOAE inhibits the proliferation and migration of A549 cells and induces apoptosis and cell cycle arrest through a mechanism that is related to the inhibition of JAK2/STAT3 pathway activation. Thus, this extract has potential for preventing and treating lung cancer.

The Root Extract of Scutellaria baicalensis Induces Apoptosis in EGFR TKI-Resistant Human Lung Cancer Cells by Inactivation of STAT3

Resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) is a major obstacle in managing lung cancer. The root of Scutellaria baicalensis (SB) traditionally used for fever clearance and detoxification possesses various bioactivities including anticancer effects. The purpose of this study was to investigate whether SB exhibited anticancer activity in EGFR TKI-resistant lung cancer cells and to explore the underlying mechanism. We used four types of human lung cancer cell lines, including H1299 (EGFR wildtype; EGFR TKI-resistant), H1975 (acquired TKI-resistant), PC9/ER (acquired erlotinib-resistant), and PC9/GR (acquired gefitinib-resistant) cells. The ethanol extract of SB (ESB) decreased cell viability and suppressed colony formation in the four cell lines. ESB stimulated nuclear fragmentation and the cleavage of poly(ADP-ribose) polymerase (PARP) and caspase-3. Consistently, the proportion of sub-G1 phase cells and annexin V+ cells were significantly elevated by ESB, indicating that ESB induced apoptotic cell death in EGFR TKI-resistant cells. ESB dephosphorylated signal transducer and activator of transcription 3 (STAT3) and downregulated the target gene expression. The overexpression of constitutively active STAT3 reversed ESB-induced apoptosis, suggesting that ESB triggered apoptosis in EGFR TKI-resistant cells by inactivating STAT3. Taken together, we propose the potential use of SB as a novel therapeutic for lung cancer patients with EGFR TKI resistance.

An update on investigational therapies that target STAT3 for the treatment of cancer

INTRODUCTION

Signal transducer and activator of transcription 3 (STAT3) is involved in cancer initiation and resistance to chemo-radiation therapies and targeted agents. The role of STAT3 in inflammation and immunity together with its involvement in a variety of diseases including genitourinary, gastrointestinal, lung, ovarian and brain tumors makes STAT3 an ideal candidate for therapeutic strategies.

AREAS COVERED

The authors provided an overview on STAT3 inhibitors and examined the most recent results obtained by these agents in cancer patients. The authors discussed the results published since 2015 and the ongoing clinical trials on anti-STAT3 agents in cancer patients. The authors also provide our opinion on the future perspectives of this therapeutic approach in this context. The manuscript includes information from trial databases and scientific literature.

EXPERT OPINION

Future challenges include the development of non-peptide small-molecule inhibitors of STAT3 designed to directly inhibit STAT3 activity. In addition, inhibitors of STAT3/STAT3 nuclear translocation or DNA binding activity are also emerging as novel promising therapeutic approaches A better comprehension of the role of STAT3 in modulating immune response together with advances in understanding the mechanisms of STAT3-induced chemo and/or radio-resistance will also help the design of combined strategies in cancer patients.

CD43 (sialophorin) is involved in the induction of extracellular matrix remodeling and angiogenesis by lung cancer cells

Aberrant expression of CD43 in malignant tumors of nonhematopoietic origin such as those from lung, cervix, colon, and breast has been shown to correlate with poor prognosis, providing tumor cells with enhanced motility, anchorage-independent growth, and in vivo tumor size, while protecting the cells of NK lysis and apoptosis. To further characterize the role of CD43 in cell transformation, we tested whether interfering its expression modified the capacity of the A549 non-small cell lung cancer cells to secrete molecules contributing to malignancy. The proteomic analysis of the secretome of serum-starved A549 cells revealed that cells expressing normal levels of CD43 released significantly high levels of molecules involved in extracellular matrix organization, angiogenesis, platelet degranulation, collagen degradation, and inflammation, as compared to CD43 RNAi cells. This data reveals a novel and unexpected role for CD43 in lung cancer development, mainly in remodeling the tumor microenvironment.

Anwulignan is a novel JAK1 inhibitor that suppresses non-small cell lung cancer growth

Anwulignan is a monomer compound derived from Schisandra sphenanthera lignans. It has been reported to possess a spectrum of pharmacological activities, including anti-bacterial, anti-inflammatory, anticancer and hepatoprotective properties. However, its anticancer capacity and molecular mechanism(s) against non-small cell lung cancer (NSCLC) have not been fully elucidated. Anwulignan significantly inhibited cell growth and increased G1-phase cell cycle arrest in NSCLC cells. Anwulignan strongly attenuates the JAK1/STAT3 signalling pathway by directly targeting JAK1 protein kinase activity in vitro. The anticancer activity by Anwulignan is dependent upon the JAK1 protein expression. Remarkably, Anwulignan strongly inhibited tumour growth in vivo. In conclusion, Anwulignan is a novel JAK1 inhibitor that may have therapeutic implications for NSCLC management.

Paeonol Suppresses Proliferation and Motility of Non-Small-Cell Lung Cancer Cells by Disrupting STAT3/NF-κB Signaling

Background: Targeting inflammatory microenvironment is a promising anti-tumor strategy. Paeonol is a phenolic compound with effective anti-inflammatory and anti-tumor properties. However, the effects of paeonol on non-small cell carcinoma (NSCLC) have not been fully investigated. Here, we evaluated the effects of paeonol on proliferation and metastasis of NSCLC and elucidated the underlying mechanisms.

Methods: The effects of paeonol on inflammatory cytokines were determined by cell proliferation and ELISA assays. Assays of wound healing, single cell migration and perforation invasion were used to evaluate migration and invasion of NSCLC cells. Expression of marker proteins in epithelial-mesenchymal transition (EMT) and matrix metalloproteinase (MMP) family enzymes were detected by Western blot assays. Nude mouse A549 cells transplantation tumor model was used to study the anti-lung cancer effects of paeonol in vivo. TUNEL stanining were used to detect the apoptosis of tumor cells in A549 lung cancer mice, and Ki67 analysis was used to detect the proliferation of tumor cells in A549 lung cancer mice. Immunohistochemistry was used to detect the effects of paeonol on signaling molecules in tumor tissues.

Results: Paeonol inhibited A549 cancer cell migration and invasion in vitro. Paeonol inhibited secreaion of inflammatory cytokines in A549 cells, including tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β, and transforming growth factor (TGF)-β. Paeonol altered the expression of marker proteins involved in EMT and MMP family enzymes. In addition, paeonol inhibited the transcriptional activity of nuclear factor-κB (NF-κB) and phosphorylation of signal transducers and activators of transcription 3 (STAT3). Paeonol inhibited the growth of A549 cells transplanted tumors in nude mice.

Conclusion: Paeonol potently inhibited NSCLC cell growth, migration and invasion associated with disruption of STAT3 and NF-κB pathways, suggesting that it could be a promising anti-metastatic candidate for tumor chemotherapy.

STAT3 Pathway in Gastric Cancer: Signaling, Therapeutic Targeting and Future Prospects

Molecular signaling pathways play a significant role in the regulation of biological mechanisms, and their abnormal expression can provide the conditions for cancer development. The signal transducer and activator of transcription 3 (STAT3) is a key member of the STAT proteins and its oncogene role in cancer has been shown. STAT3 is able to promote the proliferation and invasion of cancer cells and induces chemoresistance. Different downstream targets of STAT3 have been identified in cancer and it has also been shown that microRNA (miR), long non-coding RNA (lncRNA) and other molecular pathways are able to function as upstream mediators of STAT3 in cancer. In the present review, we focus on the role and regulation of STAT3 in gastric cancer (GC). miRs and lncRNAs are considered as potential upstream mediators of STAT3 and they are able to affect STAT3 expression in exerting their oncogene or onco-suppressor role in GC cells. Anti-tumor compounds suppress the STAT3 signaling pathway to restrict the proliferation and malignant behavior of GC cells. Other molecular pathways, such as sirtuin, stathmin and so on, can act as upstream mediators of STAT3 in GC. Notably, the components of the tumor microenvironment that are capable of targeting STAT3 in GC, such as fibroblasts and macrophages, are discussed in this review. Finally, we demonstrate that STAT3 can target oncogene factors to enhance the proliferation and metastasis of GC cells.

Cathelicidin Modulates Vascular Smooth Muscle Cell Phenotypic Switching through ROS/IL-6 Pathway

Vascular smooth muscle cells (VSMC) are stromal cells of the blood vessels and their differentiation is thought to be essential during atherosclerosis. Cathelicidin-related antimicrobial peptides (CRAMP) are suggested to play a role in the development of atherosclerosis. Even so, the relationship of CRAMP and VSMC remains unclear. The present study was to determine whether CRAMP regulates VSMC phenotypic transformation and underlying mechanisms. We demonstrated that CRAMP could reverse platelet-derived growth factor-BB (PDGF-BB)-induced VSMC phenotypic transformation, evidencing by increasing α-smooth muscle actin (α-SMA), smooth muscle 22α (SM22α) and decreasing of proliferation and migration. Further studies showed that CRAMP inhibited nuclear factor κB (NF-κB)-induced autocrine of interleukin-6 (IL-6), which further activated of janus kinase 2 (JAK2)/signal transducer and activator 3 (STAT3). Meanwhile, our data showed that CRAMP can significantly inhibit PDGF-BB enhanced intracellular reactive oxygen species (ROS) level which further affected the NF-κB signaling pathway, indicating that CRAMP can regulate the phenotypic transformation of VSMC by regulating oxidative stress. These results indicated that CRAMP regulated the differentiation of VSMC by inhibiting ROS-mediated IL-6 autocrine, suggesting that targeting CRAMP is a potential avenue for regulating the differentiation of VSMC and treatment of atherosclerosis.