Overexpression of FHL1 suppresses papillary thyroid cancer proliferation and progression via inhibiting Wnt/ß-catenin pathway.

PURPOSE: The four and a half LIM domain protein 1 (FHL1) has been found to act as a tumor suppressor in several cancers. However, the clinical and functional significance, as well as underlying molecular mechanisms of FHL1 in papillary thyroid cancer (PTC) are largely unknown. METHODS: Bioinformatics analyses, qRT-PCR and Western blotting were used to investigate the expression of FHL1 in PTC. Cell proliferation was measured using CCK8, Edu, colony formation, and flow cytometry assays. Cell migration and invasion were examined by wound healing and Transwell assays. qRT-PCR, Western blot, immunofluorescence and Top/Fop reporter assays were performed to assess the underlying mechanisms. RESULTS: FHL1 expression was significantly downregulated in PTC. FHL1 downregulation negatively correlated with stage, T classification, and N classification of the patients. The downregulation of FHL1 is associated with poor prognosis. Overexpression of FHL1 inhibited PTC cells' proliferation, invasion, migration and Wnt/ß-catenin pathway activity. LiCl partially restored the inhibitory effects of FHL1 on aggressive phenotypes and Wnt/ß-catenin pathway activity of PTC cells. CONCLUSION: FHL1 is downregulated in PTC and its expression is associated with better clinical outcomes for patients with the disease. FHL1 acts as a tumor suppressor via, at least partially, suppressing Wnt/ß-catenin pathway.

Loss of STARD13 contributes to aggressive phenotype transformation and poor prognosis in papillary thyroid carcinoma.

PURPOSE: StAR Related Lipid Transfer Domain Containing 13 (STARD13) serves as a tumor suppressor and has been characterized in several types of malignancies. However, the role and the molecular mechanism of STARD13 in regulating the progression of papillary thyroid carcinoma (PTC) remain underexplored. METHODS: The gene expression and clinical information of thyroid cancer were downloaded using "TCGAbiolinks" R package. Quantitative PCR and immunohistochemical staining were conducted to detect the expression of STARD13 in clinical tumor and adjacent non-tumor samples. Wound-healing assay, Transwell assay and 3D spheroid invasion assay were performed to evaluate the migratory and invasive capacities of PTC cells. Cell proliferation ability was determined by CCK-8 assay, colony formation assay and 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay. The alterations of indicated proteins were detected by Western blotting. RESULTS: In the present study, we found that STARD13 was significantly underexpressed in PTC, which was correlated with poor prognosis. Downregulation of STARD13 might be due to methylation of promoter region. Loss-and gain-of-function experiments demonstrated that STARD13 impeded migratory and invasive capacities of PTC cells in vitro and in vivo. In addition, we found that STARD13 regulated the morphology of PTC cells and inhibited epithelial-mesenchymal transition (EMT). CONCLUSION: Our results suggest that STARD13 acts as a metastasis suppressor and might be a potential therapeutic target in PTC.

WNT2-SOX4 positive feedback loop promotes chemoresistance and tumorigenesis by inducing stem-cell like properties in gastric cancer.

Gastric cancer (GC) is characterized by its vigorous chemoresistance to current therapies, which is attributed to the highly heterogeneous and immature phenotype of cancer stem cells (CSCs) during tumor initiation and progression. The secretory WNT2 ligand regulates multiple cancer pathways and has been demonstrated to be a potential therapeutic target for gastrointestinal tumors; however, its role involved in gastric CSCs (GCSCs) remains unclear. Here, we found that overexpression of WNT2 enhanced stemness properties to promote chemoresistance and tumorigenicity in GCSCs. Mechanistically, WNT2 was positively regulated by its transcription factor SOX4, and in turn, SOX4 was upregulated by the canonical WNT2/FZD8/ß-catenin signaling pathway to form an auto-regulatory positive feedback loop, resulting in the maintenance of GCSCs self-renewal and tumorigenicity. Furthermore, simultaneous overexpression of both WNT2 and SOX4 was correlated with poor survival and reduced responsiveness to chemotherapy in clinical GC specimens. Blocking WNT2 using a specific monoclonal antibody significantly disrupted the WNT2-SOX4 positive feedback loop in GCSCs and enhanced the chemotherapeutic efficacy when synergized with the chemo-drugs 5-fluorouracil and oxaliplatin in a GCSC-derived mouse xenograft model. Overall, this study identified a novel WNT2-SOX4 positive feedback loop as a mechanism for GCSCs-induced chemo-drugs resistance and suggested that the WNT2-SOX4 axis may be a potential therapeutic target for gastric cancer treatment.

Targeting LGSN restores sensitivity to chemotherapy in gastric cancer stem cells by triggering pyroptosis.

Gastric cancer (GC) is notoriously resistant to current therapies due to tumor heterogeneity. Cancer stem cells (CSCs) possess infinite self-renewal potential and contribute to the inherent heterogeneity of GC. Despite its crucial role in chemoresistance, the mechanism of stemness maintenance of gastric cancer stem cells (GCSCs) remains largely unknown. Here, we present evidence that lengsin, lens protein with glutamine synthetase domain (LGSN), a vital cell fate determinant, is overexpressed in GCSCs and is highly correlated with malignant progression and poor survival in GC patients. Ectopic overexpression of LGSN in GCSC-derived differentiated cells facilitated their dedifferentiation and treatment resistance by interacting with vimentin and inducing an epithelial-to-mesenchymal transition. Notably, genetic interference of LGSN effectively suppressed tumor formation by inhibiting GCSC stemness maintenance and provoking gasdermin-D-mediated pyroptosis through vimentin degradation/NLRP3 signaling. Depletion of LGSN combined with the chemo-drugs 5-fluorouracil and oxaliplatin could offer a unique and promising approach to synergistically rendering this deadly cancer eradicable in vivo. Our data place focus on the role of LGSN in GCSC regeneration and emphasize the critical importance of pyroptosis in battling GCSC.

Frizzled Receptors as Potential Therapeutic Targets in Human Cancers.

Frizzled receptors (FZDs) are a family of seven-span transmembrane receptors with hallmarks of G protein-coupled receptors (GPCRs) that serve as receptors for secreted Wingless-type (WNT) ligands in the WNT signaling pathway. Functionally, FZDs play crucial roles in regulating cell polarity, embryonic development, cell proliferation, formation of neural synapses, and many other processes in developing and adult organisms. In this review, we will introduce the basic structural features and review the biological function and mechanism of FZDs in the progression of human cancers, followed by an analysis of clinical relevance and therapeutic potential of FZDs. We will focus on the development of antibody-based and small molecule inhibitor-based therapeutic strategies by targeting FZDs for human cancers.

FZD7 is a novel prognostic marker and promotes tumor metastasis via WNT and EMT signaling pathways in esophageal squamous cell carcinoma.

Frizzled (FZD) proteins are receptors for secreted WNT proteins and play a critical role in the malignant progression of various cancers. However, the role of human FZD family members in esophageal squamous cell carcinoma (ESCC) was rarely investigated. In this study, we found that the FZD7 gene was the most commonly up-regulated FZD member in ESCC cell lines compared with other FZDs. TMA studies further validated that FZD7 protein was up-regulated in 165 of 252 (65.5%) informative ESCC patients and significantly correlated with poor overall survival (P=0.001). Additionally, multivariate Cox regression analysis showed that FZD7 overexpression was an independent prognostic factor for ESCC patients. Ectopic expression of FZD7 could promote ESCC cell metastasis both in vitro and in vivo. Under WNT3A stimulation, FZD7 was able to induce the nuclear translocation of ß-catenin and activate the downstream targets of WNT/ß-catenin signaling, as well as promote epithelial-mesenchymal transition (EMT) potential in ESCC cells. Our study demonstrated for the first time that FZD7 contributes to the malignant progression of ESCC and represents a novel prognostic marker and a potential therapeutic target for ESCC patients.

RNA editing of SLC22A3 drives early tumor invasion and metastasis in familial esophageal cancer.

Like many complex human diseases, esophageal squamous cell carcinoma (ESCC) is known to cluster in families. Familial ESCC cases often show early onset and worse prognosis than the sporadic cases. However, the molecular genetic basis underlying the development of familial ESCC is mostly unknown. We reported that SLC22A3 is significantly down-regulated in nontumor esophageal tissues from patients with familial ESCC compared with tissues from patients with sporadic ESCCs. A-to-I RNA editing of the SLC22A3 gene results in its reduced expression in the nontumor esophageal tissues of familial ESCCs and is significantly correlated with lymph node metastasis. The RNA-editing enzyme ADAR2, a familial ESCC susceptibility gene identified by our post hoc genome-wide association study, is positively correlated with the editing level of SLC22A3 Moreover, functional studies showed that SLC22A3 is a metastasis suppressor in ESCC, and deregulation of SLC22A3 facilitates cell invasion and filopodia formation by reducing its direct association with α-actinin-4 (ACTN4), leading to the increased actin-binding activity of ACTN4 in normal esophageal cells. Collectively, we now show that A-to-I RNA editing of SLC22A3 contributes to the early development and progression of familial esophageal cancer in high-risk individuals.