These findings uncover a novel mechanism of erlotinib resistance and provide a novel approach to overcome resistance by blocking the STAT3/Bcl2/Bcl-XL survival signaling pathway in human lung cancer.
Given that the activation of STAT3 is observed in nearly 50% of Lung cancers and more and more researches regarding STAT3 in tumors, here in, we reviewed the contribution of STAT3 to lung cancer growth and progression and then the context in which positive and negative regulation of STAT activation leading to cell competition provides a mechanism for therapeutic intervention for specific cancers is discussed.
STAT3 CC (rs3 816 769) and AA genotypes (rs744 166) were associated with lower lung cancer risk, whereas TT (rs3 816 769) and GG genotypes (rs744 166) were found to be associated with significantly elevated lung cancer risk.
Moreover, exogenous IL-6 treatment stimulated Stat3 activation, enhanced TGF-β-induced expression of p-Smad3 and Snail, aggravated the EMT process, and increased lung cancer cell migration and invasion induced by TGF-β1.
In this study, the effects of chemically modified anti-STAT3 small interfering (si)RNAs on cell viability, proliferation and apoptosis of parental and cisplatin resistant non-small cell lung cancer (NSCLC) cells were investigated with the aim to provide a new therapeutic strategy for overcoming cisplatin resistance in lung cancer.
We examined IL-6/STAT3 in lung cancer tumor tissues and the effects of siltuximab, a neutralizing antibody to human IL-6, in mouse models of lung cancer.
In conclusion, the c.599C>G mutation may be a new single nucleotide polymorphism of IL6ST, but mutations in exon 6 of this gene are not apparently common genetic variations occurring and leading to constitutive activation of STAT3 in lung cancer.
IL6 signaling was blocked with antibodies against IL6, soluble glycoprotein 130 Fc fragments, and the signal transducers and activators of transcription 3 inhibitor NSC74859; a constitutively active form of STAT3 was expressed in colon and lung cancer cell lines to replicate IL6R signaling.
STAT3 is considered to play an oncogenic role in several malignancies including lung cancer; consequently, targeting STAT3 is currently proposed as therapeutic intervention.
Importantly, we demonstrated that BBR was able to inhibit doxorubicin (DOX)-mediated STAT3 activation and sensitize lung cancer cells to the cytotoxic effect of DOX treatment.
Systemic delivery of the unformulated ASO, AZD9150, decreased STAT3 expression in a broad range of preclinical cancer models and showed antitumor activity in lymphoma and lung cancer models.
We showed that miR-1207-5p inhibited lung cancer cell A549 proliferation, migration and invasion in vitro, and suppressed the STAT3 and AKT signalings. miR-1207-5p overexpression can increase HUVEC angiogenesis, and can modulate the M2 phenotype of macrophage. miR-1207-5p also significantly inhibited A549 cells metastasis in a nude mouse xenograft model. miR-1207-5p and CSF1 expression levels and their relationship with lung cancer survival and metastasis status were assayed by means of a lung cancer tissue microarray.
Moreover, in a mouse lung cancer xenograft model, RES significantly inhibited the tumor growth, which was associated with inhibition of cell proliferation and decreased expression of p-STAT3 in tumor tissues.
6-OAP formed hydrogen bonds with Ser611/Ser613/Arg609 at the SH2 domain of STAT3 and inhibited the constitutive and interleukin-6-induced phosphorylated STAT3 (pSTAT3), leading to inhibitory effects on lung cancer cells and suppression of Skp2 transcription.
Collectively, these preclinical findings identify trans-signalling via STAT3 as the signalling modality by which IL-6 promotes muscle wasting in lung cancer cachexia, and therefore support the clinical evaluation of the IL-6 trans-signalling/STAT3 axis as a therapeutic target in advanced lung cancer patients presenting with cachexia.
We found that antitumor type 1 CD4<sup>+</sup> T-helper (Th1) cells and CD8<sup>+</sup> T cells were directly counter balanced in lung cancer development with tumor-promoting myeloid-derived suppressor cells (MDSCs) and suppressive macrophages, and that activation of STAT3 in MDSCs and macrophages promoted tumorigenesis through pulmonary recruitment and increased resistance of suppressive cells to CD8<sup>+</sup> T cells, enhancement of cytotoxicity toward CD4<sup>+</sup> and CD8<sup>+</sup> T cells, induction of regulatory T cell (Treg), inhibition of dendritic cells (DC), and polarization of macrophages toward the M2 phenotype.