Follistatin-like protein 1 (FSTL1) plays a critical role in lung organogenesis, but is downregulated during lung cancer development and progression. The prognostic significance and functional consequences of FSTL1 downregulation in lung cancer are unclear. Here, reduced levels of FSTL1 were detected in various tumors compared with normal tissues and were associated with poor clinical outcome in patients with non–small cell lung cancer, particularly those with lung adenocarcinoma. FSTL1 expression negatively correlated with the metastatic potential of lung cancer cells. Antibody-based neutralization of extracellular FSTL1 increased cellular migration/invasion while addition of recombinant FSTL1 protein diminished the metastatic capacity of lung cancer cells in vitro and in vivo. Notably, treatment with FSTL1 effectively prevented the metastatic progression of lung cancer cells in an orthotopic animal model. Mechanistically, FSTL1 directly bound to the proform of secreted phosphoprotein 1 (SPP1)/osteopontin, restraining proteolytic activation of SPP1, which led to inactivation of integrin/CD44-associated signaling and rearrangement of the actin cytoskeleton. Combined low expression of FSTL1 and high expression of SPP1 predicted a poorer prognosis for patients with lung cancer. This study highlights the novel interaction between FSTL1 and SPP1 and new opportunities to effectively target SPP1-driven metastatic cancers characterized by FSTL1 downregulation. Significance: These findings describe the novel interaction between FSTL1 and SPP1 and its role in the metastatic progression of lung adenocarcinoma.

Parathyroid Hormone-Like Hormone (PTHLH) is an autocrine/paracrine ligand that is up-regulated in head and neck squamous cell carcinoma (HNSCC). However, the cellular function and regulatory mechanism in HNSCC remains obscure. We investigated the clinical significance of PTHLH in HNSCC patients, and verified the role of RUNX2/PTHLH axis, which is stimulated HNSCC cell growth. In patients, PTHLH is a poor prognosis marker. PTHLH expression lead to increasing the cell proliferation potential through an autocrine/paracrine role and elevating blood calcium level in Nod-SCID mice. In public HNSCC microarray cohorts, PTHLH is found to be co-expressed with RUNX2. Physiologically, PTHLH is regulated by RUNX2 and also acting as key calcium regulator. However, elevations of calcium concentration also increased the RUNX2 expression. PTHLH, calcium, and RUNX2 form a positive feedback loop in HNSCC. Furthermore, ectopic RUNX2 expression also increased PTHLH expression and promoted proliferation potential through PTHLH expression. Using cDNA microarray analysis, we found PTHLH also stimulated expression of cell cycle regulators, namely CCNA2, CCNE2, and CDC25A in HNSCC cells, and these genes are also up-regulated in HNSCC patients. In summary, our results reveal that PTHLH expression is a poor prognosis marker in HNSCC patients, and RUNX2-PTHLH axis contributes to HNSCC tumor growth.

Chaperonin-containing TCP-1 (CCT) is a chaperonin composed of eight subunits that participates in intracellular protein folding. Here, we showed that increased levels of subunits of CCT, particularly CCT-β, were significantly correlated with lower survival rates for cancer patients. Endogenously high expression of CCT-β was found in cancer cell lines, such as the triple-negative breast cancer cell line MDA-MB-231 and the highly metastatic non-small-cell lung cancer cell line CL1-5. Knocking down CCT-β in these cancer cells led to decreased levels of anti-apoptotic proteins, such as XIAP, as well as inhibited phosphorylation of Ser473-AKT and GSK3, resulting in decrease of the nucleus-entering form of β-catenin; these changes reduced the chemoresistance and migration/invasion of the cells. Conversely, overexpression of CCT-β recovered the chemoresistance and cell migration/invasion by promoting the AKT-GSK3β-β-catenin and XIAP-Survivin pathways. Coimmunoprecipitation data revealed that the CCT complex might directly bind and stabilize XIAP and β-catenin. This study not only elucidates the roles of CCT in chemoresistance and metastasis, which are two major obstacles for current cancer therapy, but also provides a possible therapeutic strategy against cancers with overexpressed CCT-β.

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype because of its high metastatic potential. Immune evasion due to aberrant expression of programmed cell death ligand 1 (PD-L1) has also been reported recently in metastatic TNBC. However, the mechanism underlying metastatic progression and PD-L1 upregulation in TNBC is still largely unknown. Here, we found that guanylate binding protein 5 (GBP5) is expressed in higher levels in TNBC tissues than in non-TNBC and normal mammary tissues and serves as a poorer prognostic marker in breast cancer patients. Transwell cultivation indicated that GBP5 expression is causally related to cellular migration ability in the detected TNBC cell lines. Moreover, the computational simulation of the gene set enrichment analysis (GSEA) program against the GBP5 signature generated from its coexpression with other somatic genes in TNBC revealed that GBP5 upregulation may be associated with the activation of interferon gamma (IFN-γ)-responsive and NF-κB-related signaling cascades. In addition, we found that the coexpression of GBP5 with PD-L1 was significantly positive correlation in TNBC tissues. Robustly, our data showed that GBP5 knockdown in TNBC cells harboring a higher GBP5 level dramatically suppresses the number of migrated cells, the activity of IFN-γ/STAT1 and TNF-α/NF-κB signaling axes, and the expression of PD-L1. Importantly, the signature combining a higher GBP5 and PD-L1 level predicted the shortest time interval of brain metastasis in breast cancer patients. These findings not only uncover the oncogenic function of GBP5 but also provide a new strategy to combat metastatic/immunosuppressive TNBC by targeting GBP5 activity.

Glioblastoma multiforme (GBM) is the most aggressive brain tumor and has a poor prognosis and is poorly sensitive to radiotherapy or temozolomide (TMZ) chemotherapy. Therefore, identifying new biomarkers to predict therapeutic responses of GBM is urgently needed. By using The Cancer Genome Atlas (TCGA) database, we found that the upregulation of histone 2A family member J (H2AFJ), but not other H2AFs, is extensively detected in the therapeutic-insensitive mesenchymal, IDH wildtype, MGMT unmethylated, or non-G-CIMP GBM and is associated with poor TMZ responsiveness independent of radiation. Similar views were also found in GBM cell lines. Whereas H2AFJ knockdown diminished TMZ resistance, H2AFJ overexpression promoted TMZ resistance in a panel of GBM cell lines. Gene set enrichment analysis (GSEA) revealed that H2AFJ upregulation accompanied by the activation of TNF-α/NF-κB and IL-6/STAT3-related pathways is highly predicted. Luciferase-based promoter activity assay further validated that the activities of NF-κB and STAT3 are causally affected by H2AFJ expression in GBM cells. Moreover, we found that therapeutic targeting HADC3 by tacedinaline or NF-κB by ML029 is likely able to overcome the TMZ resistance in GBM cells with H2AFJ upregulation. Significantly, the GBM cohorts harboring a high-level H2AFJ transcript combined with high-level expression of TNF-α/NF-κB geneset, IL-6/STAT3 geneset or HADC3 were associated with a shorter time to tumor repopulation after initial treatment with TMZ. These findings not only provide H2AFJ as a biomarker to predict TMZ therapeutic effectiveness but also suggest a new strategy to combat TMZ-insensitive GBM by targeting the interaction network constructed by TNF-α/NF-κB, IL-6/STAT3, HDAC3, and H2AFJ.

Cancer metastasis leading to the dysfunction of invaded organs is the main cause of the reduced survival rates in lung cancer patients. However, the molecular mechanism for lung cancer metastasis remains unclear. Recently, the increased activity of inflammasome appeared to correlate with the metastatic progression and immunosuppressive ability of various cancer types. Our results showed that the mRNA levels of absence in melanoma 2 (AIM2), one of the inflammasome members, are extensively upregulated in primary tumors compared with normal tissues derived from the TCGA lung adenocarcinoma (LUAD) database. Moreover, Kaplan‐Meier analysis demonstrated that a higher mRNA level of AIM2 refers to a poor prognosis in LUAD patients. Particularly, AIM2 upregulation is closely correlated with smoking history and the absence of EGFR/KRAS/ALK mutations in LUAD. We further showed that the endogenous mRNA levels of AIM2 are causally associated with the metastatic potentials of the tested LUAD cell lines. AIM2 knockdown suppressed but overexpression promoted the migration ability and lung colony–forming ability of tested LUAD cells. In addition, we found that AIM2 upregulation is closely associated with an increased level of immune checkpoint gene set, as well as programmed cell death‐ligand 1 (PD‐L1) transcript, in TCGA LUAD samples. AIM2 knockdown predominantly repressed but overexpression enhanced PD‐L1 expression via altering the activity of PD‐L1 transcriptional regulators NF‐κB/STAT1 in LUAD cells. Our results not only provide a possible mechanism underlying the AIM2‐promoted metastatic progression and immune evasion of LUAD but also offer a new strategy for combating metastatic/immunosuppressive LUAD via targeting AIM2 activity.