Mutations in EGFR drive tumor growth but render tumor cells sensitive to treatment with EGFR tyrosine kinase inhibitors (TKI). Phenotypic alteration in epithelial-to-mesenchymal transition (EMT) has been linked to the TKI resistance in lung adenocarcinoma. However, the mechanism underlying this resistance remains unclear. Here we report that high expression of a neuroendocrine factor termed VGF induces the transcription factor TWIST1 to facilitate TKI resistance, EMT, and cancer dissemination in a subset of lung adenocarcinoma cells. VGF silencing resensitized EGFR-mutated lung adenocarcinoma cells to TKI. Conversely, overexpression of VGF in sensitive cells conferred resistance to TKIs and induced EMT, increasing migratory and invasive behaviors. Correlation analysis revealed a significant association of VGF expression with advanced tumor grade and poor survival in patients with lung adenocarcinoma. In a mouse xenograft model of lung adenocarcinoma, suppressing VGF expression was sufficient to attenuate tumor growth. Overall, our findings show how VGF can confer TKI resistance and trigger EMT, suggesting its potential utility as a biomarker and therapeutic target in lung adenocarcinoma. .

Regulation of the stemness factor, SOX2, by cytokine stimuli controls self-renewal and differentiation in cells. Activating mutations in EGFR are proven therapeutic targets for tyrosine kinase inhibitors (TKI) in lung adenocarcinoma, but acquired resistance to TKIs inevitably occurs. The mechanism by which stemness and differentiation signaling emerge in lung cancers to affect TKI tolerance and lung cancer dissemination has yet to be elucidated. Here, we report that cross-talk between SOX2 and TGFb signaling affects lung cancer cell plasticity and TKI tolerance. TKI treatment favored selection of lung cancer cells displaying mesenchymal morphology with deficient SOX2 expression, whereas SOX2 expression promoted TKI sensitivity and inhibited the mesenchymal phenotype. Preselection of EGFR-mutant lung cancer cells with the mesenchymal phenotype diminished SOX2 expression and TKI sensitivity, whereas SOX2 silencing induced vimentin, but suppressed BCL2L11, expression and promoted TKI tolerance. TGFb stimulation downregulated SOX2 and induced epithelial-to-mesenchymal transdifferentiation accompanied by increased TKI tolerance, which can interfere with ectopic SOX2 expression. SOX2-positive lung cancer cells exhibited a lower dissemination capacity than their SOX2-negative counterparts. Tumors expressing low SOX2 and high vimentin signature were associated with worse survival outcomes in patients with EGFR mutations. These findings provide insights into how cancer cell plasticity regulated by SOX2 and TGFb signaling affects EGFR-TKI tolerance and lung cancer dissemination.Significance: These findings suggest the potential of SOX2 as a prognostic marker in EGFR-mutant lung cancer, as SOX2-mediated cell plasticity regulated by TGFb stimulation and epigenetic control affects EGFR-TKI tolerance and cancer dissemination.

Signaling elicited by the stem cell factors SOX2, OCT4, KLF4, and MYC not only mediates reprogramming of differentiated cells to pluripotency but has also been correlated with tumor malignancy. In this study, we found SOX2 expression signifies poor recurrence-free survival and correlates with advanced pathological grade in bladder cancer. SOX2 silencing attenuated bladder cancer cell growth, while its expression promoted cancer cell survival and proliferation. Under lowserum stress, SOX2 expression promoted AKT phosphorylation and bladder cancer cells' spheroidforming capability. Furthermore, pharmacological inhibition of AKT phosphorylation, using MK2206, inhibited the SOX2-mediated spheroid formation of bladder cancer cells. Gene expression profiling showed that SOX2 expression, in turn, induced IGF2 expression, while SOX2 silencing inhibited IGF2 expression. Moreover, knocking down IGF2 and IGF1R diminished bladder cancer cell growth. Lastly, pharmacological inhibition of IGF1R, using linsitinib, also inhibited the SOX2-mediated spheroid formation of bladder cancer cells under low-serum stress. Our findings indicate the SOX2-IGF2 signaling affects the aggressiveness of bladder cancer cell growth. This signaling could be a promising biomarker and therapeutic target for bladder cancer intervention. Bladder cancer arises from the urinary bladder's epithelial lining, called the urothelium, and is one of the most common urinary system malignancies 1. Most patients are diagnosed with non-invasive bladder cancer, and surgery is the typical treatment option 2. However, just over half of these patients will experience tumor recurrence 3. Chemotherapy is the conventional treatment for patients with advanced stage bladder cancer, but few can be cured 4. Therefore, novel biomarkers for monitoring, and therapeutic targets for targeting, bladder cancer progression are urgently needed. Transcription factors involved in embryonic stem cell (ESC) and induced pluripotent stem cell (iPSC) signaling, such as SOX2, OCT4, MYC, and KLF4, have been linked to tumor progression in various cancers 5,6. Among them, SOX2 is essential to self-renewal and differentiation of several adult tissue progenitor cells 7-9. SOX2 expression has been implicated in human breast and lung cancers 10-12. Genomic amplification of SOX2 has been observed in lung squamous cell carcinoma 13 , while genomic amplification of SOX4, another SOX family member, has been reported in bladder cancer 14,15. SOX2 promotes abnormal proliferation of lung cancer cells and controls tumor initiation in skin squamous cell carcinoma 16,17. Although there is high SOX2 expression in bladder cancer 18 , the oncogenic mechanism underlying SOX2-mediated tumor malignancy remains unclear. Insulin-like growth factor 2 (IGF2), a mitogenic peptide hormone, is highly expressed during embryonic development 19 , and overexpressed in tumors associated with more aggressive status 20. Previous studies suggest that IGF2 binds to its receptor, IGF1R, to initiate tumorigenesis of breast and lung...

Hypoxia, the reduction of oxygen levels in cells or tissues, elicits a set of genes to adjust physiological and pathological demands during normal development and cancer progression. OCT4, a homeobox transcription factor, is essential for self-renewal of embryonic stem cells, but little is known about the role of OCT4 in non-germ-cell tumorigenesis. Here, we report that hypoxia stimulates a short isoform of OCT4, called OCT4B, via a HIF2α-dependent pathway to induce the epithelial-mesenchymal transition (EMT) and facilitate cancer dissemination. OCT4B overexpression decreased epithelial barrier properties, which led to an increase in cell migration and invasion in lung cancer cells. OCT4B knockdown attenuated HIF2α-induced EMT and inhibited cancer dissemination in cell-line and animal models. We observed that OCT4B bound the SLUG promoter and enhanced its expression, and SLUG silencing inhibited OCT4B-mediated EMT, accompanied with decreased cell migration and invasion. Correlation analysis revealed that OCT4B expression was significantly associated with the SLUG level in lung tumors. These results provide novel insights into OCT4B-mediated oncogenesis in cancer dissemination.