Mutations found in cancer patients compromise DNA binding of the winged helix protein STK19.

Serine/threonine protein kinase 19 (STK19) has been reported to phosphorylate and activate oncogenic NRAS to promote melanomagenesis. However, concerns have been raised about whether STK19 is a kinase. STK19 has also been identified as a putative factor involved in the transcription-coupled nucleotide excision repair (TC-NER) pathway. In this study, we determined the 1.32 Å crystal structure of human STK19. The structure reveals that STK19 is a winged helix (WH) protein consisting of three tandem WH domains. STK19 binds more strongly to double-stranded DNA and RNA (dsDNA/dsRNA) than to ssDNA. A positively charged patch centered on helix WH3-H1 contributes to dsDNA binding, which is unusual because the WH domain typically uses helix H3 as the recognition helix. Importantly, mutations of the conserved residues in the basic patch, K186N, R200W, and R215W, are found in cancer patients, and these mutations compromise STK19 DNA binding. Other mutations have been predicted to produce a similar effect, including two mutations that disrupt the nuclear localization signal (NLS) motif. These mutations may indirectly impact the DNA binding capacity of STK19 by interfering with its nuclear localization.

Overexpressed transferrin receptor implied poor prognosis and relapse in gastrointestinal stromal tumors.

Ferroptosis, as a novel-induced programmed cell death, plays critical roles in the pathogenesis of cancers. However, the promising biomarkers of ferroptosis in gastrointestinal stromal tumor (GIST) remain to be elucidated. Herein, the expression of ferroptosis-related genes was analyzed in GIST. Among the 64 ferroptosis-related genes, transferrin receptor (TFRC) expression presented a remarkable upregulation in high-risk patients through Gene Expression Omnibus (GEO) dataset analysis, as well as its significant change after imatinib was treated. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of TFRC-relevant genes revealed that TFRC expression was closely associated with cell growth pathways and metabolism-related pathways. Furthermore, patients at high risk of recurrence were more likely to exhibit high TFRC expression by immunohistochemistry. Additionally, high TFRC expression indicated an undesirable state of patient relapse, which could serve as a powerful significant independent predictor of recurrence-free survival (RFS). In summary, we systematically summarize the expression characteristics and clinical relevance of TFRC and show that TFRC can be used as a prognostic factor, which can be considered a potential therapeutic target in GIST.

NUMA1 modulates apoptosis of esophageal squamous cell carcinoma cells through regulating ASK1-JNK signaling pathway.

Esophageal squamous cell carcinoma (ESCC) is a common malignancy worldwide with a low survival rate due to a lack of therapeutic targets. Here, our results showed that nuclear mitotic apparatus protein 1 (NUMA1) transcript and protein levels are significantly upregulated in ESCC patient samples and its high expression predicated poor prognosis. Knock-down of NUMA1 promoted cell apoptosis and suppressed cell proliferation and colony formation. By using cell-derived xenograft (CDX) and patient-derived xenograft (PDX) mice models, we found silencing the NUMA1 expression suppressed tumor progression. In addition, conditional knocking-out of NUMA1 reduced 4NQO-induced carcinogenesis in mice esophagus, which further confirmed the oncogenic role of NUMA1 in ESCC. Mechanistically, from the immunoprecipitation assay we revealed that NUMA1 interacted with GSTP1 and TRAF2, promoted the association of TRAF2 with GSTP1 while inhibited the interaction of TRAF2 and ASK1, thus to regulate sustained activation of JNK. In summary, our findings suggest that NUMA1 plays an important role during ESCC progression and it functions through regulating ASK1-MKK4-SAPK/JNK signaling pathway.

Erianin suppresses constitutive activation of MAPK signaling pathway by inhibition of CRAF and MEK1/2.

Constitutive activation of RAS-RAF-MEK-ERK signaling pathway (MAPK pathway) frequently occurs in many cancers harboring RAS or RAF oncogenic mutations. Because of the paradoxical activation induced by a single use of BRAF or MEK inhibitors, dual-target RAF and MEK treatment is thought to be a promising strategy. In this work, we evaluated erianin is a novel inhibitor of CRAF and MEK1/2 kinases, thus suppressing constitutive activation of the MAPK signaling pathway induced by BRAF V600E or RAS mutations. KinaseProfiler enzyme profiling, surface plasmon resonance (SPR), isothermal titration calorimetry (ITC), cellular thermal shift assay, computational docking, and molecular dynamics simulations were utilized to screen and identify erianin binding to CRAF and MEK1/2. Kinase assay, luminescent ADP detection assay, and enzyme kinetics assay were investigated to identify the efficiency of erianin in CRAF and MEK1/2 kinase activity. Notably, erianin suppressed BRAF V600E or RAS mutant melanoma and colorectal cancer cell by inhibiting MEK1/2 and CRAF but not BRAF kinase activity. Moreover, erianin attenuated melanoma and colorectal cancer in vivo. Overall, we provide a promising leading compound for BRAF V600E or RAS mutant melanoma and colorectal cancer through dual targeting of CRAF and MEK1/2.

Orobol, 3'-hydroxy-genistein, suppresses the development and regrowth of cutaneous SCC.

Chronic solar ultraviolet exposure is a major risk factor for cutaneous squamous cell carcinoma (cSCC), which is the second most common type of skin cancer. Our previous data showed that total protein and phosphorylation levels of T-LAK cell-originated protein kinase (TOPK) were enhanced in solar-simulated light (SSL)-induced skin carcinogenesis and overexpressed in actinic keratosis (AK) and cSCC human skin tissues compared to those in matched normal skin. Thus, targeting TOPK activity could be a helpful approach for treating cSCC. Our data showed that orobol directly binds to TOPK in an ATP-independent manner and inhibits TOPK kinase activity. Furthermore, orobol inhibited anchorage-independent colony formation by SCC12 cells in a dose-dependent manner. After discontinuing the treatment, patients commonly return to tumor-bearing conditions; therefore, therapy or intermittent dosing of drugs must be continued indefinitely. Thus, to examine the efficacy of orobol against the development and regrowth of cSCC, we established mouse models including prevention, and therapeutic models on the chronic SSL-irradiated SKH-1 hairless mice. Early treatment with orobol attenuates chronic SSL-induced cSCC development. Furthermore, orobol showed therapeutic efficacy after the formation of chronic SSL irradiation-induced tumor. In the mouse model with intermittent dosing of orobol, our data showed that re-application of orobol is effective for reducing tumor regrowth after discontinuation of treatment. Moreover, oncogenic protein levels were significantly attenuated by orobol treatment in the SSL-stimulated human skin. Thus, we suggest that orobol, as a promising TOPK inhibitor, could have an effective clinical approach to prevent and treat the development and regrowth of cSCC.

Epigenetic compounds targeting pharmacological target lysine specific demethylase 1 and its impact on immunotherapy, chemotherapy and radiotherapy for treatment of tumor recurrence and resistance.

It has been proven that metastatic recurrence and therapeutic resistance are linked. Due to the variability of individuals and tumors, as well as the tumor's versatility in avoiding therapies, therapy resistance is more difficult to treat. Therapy resistance has significantly restricted the clinical feasibility and efficacy of tumor therapy, despite the discovery of novel compounds and therapy combinations with increasing efficacy. In several tumors, lysine specific demethylase 1 (LSD1) has been associated to metastatic recurrence and therapeutic resistance. For researchers to better comprehend how LSD1-mediated tumor therapy resistance occurs and how to overcome it in various tumors, this study focused on the role of LSD1 in tumor recurrence and therapeutic resistance. The importance of therapeutically targeted LSD1 was also discussed. Most gene pathway signatures are related to LSD1 inhibitor sensitivity. However, some gene pathway signatures, especially in AML, negatively correlate with LSD1 inhibitor sensitivity, but targeting LSD1 makes the therapy-resistant tumor sensitive to physiological doses of conventional therapy. We propose that combining LSD1 inhibitor with traditional tumor therapy can help patients attain a complete response and prevent cancer relapse.

A comprehensive comparative study on LSD1 in different cancers and tumor specific LSD1 inhibitors.

LSD1 was significantly over-expressed in several cancer types, and its aberrant overexpression was revealed to play a crucial role in the initiation and progression of cancer. Several LSD1 inhibitors that were discovered and developed so far were found to be effective in attenuating tumor growth in both in vivo and in vitro studies. However, the major challenge associated with the development of cancer therapies is personalized treatment. Therefore, it is essential to look in detail at how LSD1 plays its part in carcinogenesis and whether there are any different expression levels of LSD1 in different tumors. Here in this review, fresh insight into a list of function correlated LSD1 binding proteins are provided, and we tried to figure out the role of LSD1 in different cancer types, including hematological malignancies and solid tumors. A critical description of mutation preference for LSD1 in different tumors was also discussed. Recent research findings clearly showed that the abrogation of LSD1 demethylase activity via LSD1 inhibitors markedly reduced the growth of cancer cells. But there are still many ambiguities regarding the role of LSD1 in different cancers. Therefore, targeting LSD1 for treating different cancers is still reductionist, and many challenges need to be met to improve the therapeutic outcomes of LSD1 inhibitors.

The nerve-tumour regulatory axis GDNF-GFRA1 promotes tumour dormancy, imatinib resistance and local recurrence of gastrointestinal stromal tumours by achieving autophagic flux.

Complete surgical resection, accessible therapeutic targets and effective tyrosine kinase inhibitors (TKIs) have not completely cured gastrointestinal stromal tumours (GISTs), with most patients suffering from residual tumours and recurrence. The existence of nerve infiltration in GIST provides a way for tumour cells to escape local resection and systemic targeted therapy, which may challenge the previous understanding of its behaviour patterns and inspire the development of more radical excision and more precise targeted therapy. Moreover, tumour dormancy has emerged as a major cause of drug resistance and tumour relapse. Among these pathways, the nerve-tumour regulatory axis GDNF-GFRA1 is activated in GISTs, assists tumour cells in achieving dormancy and protects them from apoptosis under environmental stress by enhancing autophagic flux. The concrete mechanism is that the GDNF-regulating interaction between GFRA1 and the lysosomal calcium channel MCOLN1 activates Ca2+-dependent TFEB signalling. Activated TFEB transcriptionally regulates intracellular lysosome levels, which could achieve feedback upregulation of cellular autophagy flux during TKI treatment. This dormancy-transition axis fills parts of the mechanistic vacancy before the onset of secondary mutations, and strategies for TKIs combined with targeting GFRA1-dependent autophagy have distinct promise as prospective clinical therapies.

F-box only protein 9 and its role in cancer.

The F-box proteins (FBP), substrate recognition subunit of the SCF (Skp1-Cullin1-F-box protein complex) E3 ligase, play important roles in the ubiquitylation and subsequent degradation of the target proteins from several cellular processes. Disorders of F-box protein-mediated proteolysis lead to human malignancies. FBP plays an important role in many cellular processes, including cell proliferation, cell cycle, apoptosis, migration, invasion, and metastasis, suggesting that it can be associated with tumorigenesis, cancer development and progression. However, the expression and function of FBXO9 (F-box only protein 9) differ in various types of human cancer. Due to the ability to regulate the stability and activity of oncogenes and tumor-suppressor genes, and the physiological functions of many of the F-box proteins remain subtle, further genetic and mechanistic studies will elaborate and help define FBXO9's role. Targeting F-box protein or F-box protein signaling pathways could be an effective strategy for preventing or treating human cancer. This review is presented to summarize the part of FBXO9 in different types of human cancer and its regulation mechanism, and to pave the way to design FBXO9-targeting anticancer therapies.

Systematic Review and Meta-Analysis of Lysine-Specific Demethylase 1 Expression as a Prognostic Biomarker of Cancer Survival and Disease Progression.

BACKGROUND: Numerous studies on the prognostic significance of lysine-specific demethylase 1 (LSD1) up-regulation in tumors have different outcomes. The inconsistency originated from various studies looking into the association between LSD1 and tumor cells has prompted the decision of this quantitative systematic review to decipher how up-regulated LSD1 and overall survival (OS) or recurrence-free survival (RFS) or disease-free survival (DFS) are linked in tumor patients. METHODS: Articles were searched from online databases such as Embase, Web of Science Core, PubMed, Google Scholar, and Scopus. The extraction of the hazard ratios (HR) with their 95% confidence intervals (CIs) was attained and survival data of 3151 tumor patients from 17 pieces of related research were used for this meta-analysis. RESULTS: To shed light on the link between LSD1 up-regulation and the prognosis of diverse tumors, the pooled hazard ratios (HRs) with their 95% confidence intervals (CIs) were determined. In this meta-analysis, it was observed that LSD1 up-regulation is linked with poor OS (HR = 2.08, 95% CI: 1.66-2.61, P < .01) and RFS (HR = 3.09, 95% CI: 1.81-5.26, P < .01) in tumor patients. However, LSD1 up-regulation was not linked to DFS (HR = 1.49, 95% CI: .83-2.69, P = .18) in tumor patients. The subcategory examination grouped by tumor type and ethnicity showed that LSD1 up-regulation was linked with a poor outcome in the esophageal tumor and hepatocellular carcinoma and Asian patients, respectively. For clinical-pathological factors, up-regulated LSD1 was significantly linked with Lymph node status. CONCLUSION: Despite the shortfall of the present work, this meta-analysis proposes that LSD1 up-regulation may be a prognostic biomarker for patients with tumors including esophageal tumors and hepatocellular carcinoma. We propose that large-scale studies are vital to substantiate these outcomes.

Ipriflavone Suppresses Growth of Esophageal Squamous Cell Carcinoma Through Inhibiting mTOR In Vitro and In Vivo.

Ipriflavone, a synthetic isoflavone that inhibits osteoclastic bone resorption, has been used clinically for the treatment of osteoporosis. However, the anticancer activity of Ipriflavone and its molecular mechanisms in the context of esophageal squamous cell carcinoma (ESCC) have not been investigated. In this study, we report that Ipriflavone is a novel mammalian target of rapamycin (mTOR) inhibitor that suppresses cell proliferation and induces cell apoptosis in ESCC cells. Ipriflavone inhibited anchorage-dependent and -independent growth of ESCC cells. Ipriflavone induced G1 phase cell cycle arrest and intrinsic cell apoptosis by activating caspase 3 and increasing the expression of cytochrome c. Based on the results of in vitro screening and cell-based assays, Ipriflavone inhibited mTOR signaling pathway through directly targeting mTOR. Knockdown of mTOR strongly inhibited the growth of ESCC cells, and the cell growth inhibitory effect exerted by Ipriflavone was found to be dependent upon mTOR signaling pathway. Remarkably, Ipriflavone strongly inhibited ESCC patient-derived xenograft tumor growth in an in vivo mouse model. Our findings suggest that Ipriflavone is an mTOR inhibitor that could be potentially useful for treating ESCC.

Low Distribution of TIM-3+ Cytotoxic Tumor-Infiltrating Lymphocytes Predicts Poor Outcomes in Gastrointestinal Stromal Tumors.

There are multiple tumor-infiltrating lymphocytes (TILs) and relevant immune checkpoints existing in gastrointestinal stromal tumor (GIST), which provides opportunities and rationales for developing effective immunotherapies. Recent studies have suggested that checkpoint TIM-3/Gal-9 plays a pivotal role on immune response in multiple tumors, similar to the PD-1/PD-L1, emerging as a potential therapeutic target. However, their functions in GIST are unrevealed. Hence, the expression of immune checkpoints TIM-3 and Gal-9, as well as the infiltration of CD8+ T cells and NK cells, is described in 299 cases of GIST specimens. The results showed that TIM-3 and Gal-9 are mainly expressed in TILs, rarely in tumor cells. Expression levels of TIM-3 and Gal-9 significantly differ in varying risks of GIST and exert opposite distribution trends. Indicated by prognosis analysis, high TIM-3 expression of TILs was associated with improved outcome, while low expression levels of TIM-3 in combination with low amounts of CD8+ and CD56+ TILs predict extremely poor survival. The integrated analysis of TIM-3+, CD8+, and CD56+ TILs as one biomarker is a reliable independent predictor of prognosis. In conclusion, low densities of TIM-3+ TILs are associated with poor survival, and integrated immune biomarkers lead to superior predictors of GIST prognosis.

Crystal structure of the human PRPK-TPRKB complex.

Mutations of the p53-related protein kinase (PRPK) and TP53RK-binding protein (TPRKB) cause Galloway-Mowat syndrome (GAMOS) and are found in various human cancers. We have previously shown that small compounds targeting PRPK showed anti-cancer activity against colon and skin cancer. Here we present the 2.53 Å crystal structure of the human PRPK-TPRKB-AMPPNP (adenylyl-imidodiphosphate) complex. The structure reveals details in PRPK-AMPPNP coordination and PRPK-TPRKB interaction. PRPK appears in an active conformation, albeit lacking the conventional kinase activation loop. We constructed a structural model of the human EKC/KEOPS complex, composed of PRPK, TPRKB, OSGEP, LAGE3, and GON7. Disease mutations in PRPK and TPRKB are mapped into the structure, and we show that one mutation, PRPK K238Nfs*2, lost the binding to OSGEP. Our structure also makes the virtual screening possible and paves the way for more rational drug design.

Structural basis for multifunctional roles of human Ints3 C-terminal domain.

Proper repair of damaged DNA is critical for the maintenance of genome stability. A complex composed of Integrator subunit 3 (Ints3), single-stranded DNA-binding protein 1 (SSB1), and SSB-interacting protein 1 (SSBIP1) is required for efficient homologous recombination-dependent repair of double-strand breaks (DSBs) and ataxia-telangiectasia mutated (ATM)-dependent signaling pathways. It is known that in this complex the Ints3 N-terminal domain scaffolds SSB1 and SSBIP1. However, the molecular basis for the function of the Ints3 C-terminal domain remains unclear. Here, we present the crystal structure of the Ints3 C-terminal domain, uncovering a HEAT-repeat superhelical fold. Using structure and mutation analysis, we show that the C-terminal domain exists as a stable dimer. A basic groove and a cluster of conserved residues on two opposite sides of the dimer bind single-stranded RNA/DNA (ssRNA/ssDNA) and Integrator complex subunit 6 (Ints6), respectively. Dimerization is required for nucleic acid binding, but not for Ints6 binding. Additionally, in vitro experiments using HEK 293T cells demonstrate that Ints6 interaction is critical for maintaining SSB1 protein level. Taken together, our findings establish the structural basis of a multifunctional Ints3 C-terminal module, allowing us to propose a novel mode of nucleic acid recognition by helical repeat protein and paving the way for future mechanistic studies.

FN1 promotes chondrocyte differentiation and collagen production via TGF-ß/PI3K/Akt pathway in mice with femoral fracture.

Fibronectin (FN) functions as a potent stimulator of osteogenic differentiation, and bone fracture healing. In FN family, FN1 acts as an interactive protein gene product to mediate chondrocyte adhesion. However, its effect on fracture healing remains elusive. Therefore, we aimed to investigate the involvement of FN1 in fracture healing. Hard callus formations were found at fracture site with thicker periosteum in lateral cortical bone area outside the fracture site in model mice. The decreased number of osteogenic cells in the middle of the callus region and increased extracellular matrix were suggestive of successful induction. Immunoblotting and RT-qPCR revealed that expression of FN1 was increased in tissues of fracture mice. As displayed by Safranin-fast green staining hematoxylin-eosin staining, the overexpression of FN1 at fracture site promoted osteoid formation and chondrocyte differentiation. The stimulating role of FN1 in collagen production was evidenced by increased levels of Col2, Col1, ColX, Osteonectin, and Osteocalcin and enhanced BMD, BV, BV/TV and Tb.Th values verified by immunoblotting and immunohistochemical staining. Additionally, the upregulation of FN1 contributed to promoted TGF-ß, c-Caspase-9/t-Caspase-9 ratio and NF-κB p65 protein expression as well as lowered p-PI3K/PI3K and p-AKT/AKT ratios, implying the positive correlation between FN1 and the TGF-ß/PI3K/Akt signaling pathway. The key findings of the present study provided evidence indicating that overexpression of FN1 contributes to fracture healing by activation of the TGF-ß/PI3K/Akt signaling pathway.

Mesenchymal stem cell-derived exosomal microRNA-136-5p inhibits chondrocyte degeneration in traumatic osteoarthritis by targeting ELF3.

BACKGROUND: Emerging evidence suggests that microRNAs (miRs) are associated with the progression of osteoarthritis (OA). In this study, the role of exosomal miR-136-5p derived from mesenchymal stem cells (MSCs) in OA progression is investigated and the potential therapeutic mechanism explored. METHODS: Bone marrow mesenchymal stem cells (BMMSCs) and their exosomes were isolated from patients and identified. The endocytosis of chondrocytes and the effects of exosome miR-136-5p on cartilage degradation were observed and examined by immunofluorescence and cartilage staining. Then, the targeting relationship between miR-136-5p and E74-like factor 3 (ELF3) was analyzed by dual-luciferase report assay. Based on gain- or loss-of-function experiments, the effects of exosomes and exosomal miR-136-5p on chondrocyte migration were examined by EdU and Transwell assay. Finally, a mouse model of post-traumatic OA was developed to evaluate effects of miR-136-5p on chondrocyte degeneration in vivo. RESULTS: In the clinical samples of traumatic OA cartilage tissues, we detected increased ELF3 expression, and reduced miR-136-5p expression was determined. The BMMSC-derived exosomes showed an enriched level of miR-136-5p, which could be internalized by chondrocytes. The migration of chondrocyte was promoted by miR-136-5p, while collagen II, aggrecan, and SOX9 expression was increased and MMP-13 expression was reduced. miR-136-5p was verified to target ELF3 and could downregulate its expression. Moreover, the expression of ELF3 was reduced in chondrocytes after internalization of exosomes. In the mouse model of post-traumatic OA, exosomal miR-136-5p was found to reduce the degeneration of cartilage extracellular matrix. CONCLUSION: These data provide evidence that BMMSC-derived exosomal miR-136-5p could promote chondrocyte migration in vitro and inhibit cartilage degeneration in vivo, thereby inhibiting OA pathology, which highlighted the transfer of exosomal miR-136-5p as a promising therapeutic strategy for patients with OA.

Exon 11 homozygous mutations and intron 10/exon 11 junction deletions in the KIT gene are associated with poor prognosis of patients with gastrointestinal stromal tumors.

BACKGROUND: Gastrointestinal stromal tumors (GISTs) with different types of mutations exhibit different clinical characteristics and prognosis. This study aimed to evaluate the prognostic value of mutations in KIT and PDGFRA in a large-scale cohort of GIST patients with current therapy including surgery and imatinib. METHODS: A total of 1163 patients diagnosed with GISTs between January 2006 and December 2018 were enrolled in this study. Mutation analysis was performed for exons 9, 11, 13, and 17 of KIT and exons 12 and 18 of PDGFRA. Mutations were grouped into 12 categories according to the gene, exon, and involved codons; they were analyzed considering the clinical characteristics, disease-free survival (DFS), and overall survival (OS) of patients with GISTs. RESULTS: In low-risk GISTs, we identified two predictors of worse DFS: tumor origin in the rectum and KIT exon 11 deletion involving two or more codons. In high-risk GISTs treated with R0 resection and imatinib, patients with KIT exon 11 homozygous mutations and KIT intron 10/exon 11 junction deletions demonstrated the highest recurrence rate, indicating that these mutations can be independent prognostic factors of DFS. The presence of KIT exon 11 homozygous mutations also independently influenced OS. CONCLUSION: Low-incidence mutations such as KIT exon 11 homozygous mutations or intron 10/exon 11 junction deletions in GISTs should be carefully evaluated to explore novel treatment strategies, as tumors with these mutations have a high recurrence rate and a very poor prognosis after surgery followed by imatinib adjuvant treatment.

Clinicopathologic characteristics, diagnostic clues, and prognoses of patients with multiple sporadic gastrointestinal stromal tumors: a case series and review of the literature.

BACKGROUND: Most sporadic gastrointestinal stromal tumors (GISTs) occur as solitary tumors, while multiple sporadic GISTs are extremely rare and often misdiagnosed as metastatic GISTs, leading to inappropriate treatment. This study aimed to investigate the clinicopathological characteristics, diagnostic clues, and prognoses of multiple sporadic GISTs. METHODS: Twenty-seven patients with multiple sporadic GISTs and 11 patients with metastatic GISTs mimicking sporadic GISTs were analyzed. The clinicopathological characteristics, genetic mutation types, and prognoses were summarized. In addition, 1066 cases of primary GISTs with a single lesion diagnosed at the same hospital were included as controls. RESULTS: Compared with 1066 cases of primary GIST with a single lesion, multiple sporadic GISTs occurred at an older age, were more common in women than in men, and were located mainly in the stomach. They were generally small in size, had a low mitotic index and were more often rated as very low risk/low risk. Mutation analysis of all available lesions revealed different KIT/PDGFRA mutation patterns among tumors from the same patients. No patient relapsed during the follow-up period. Among 11 patients with metastatic GISTs that mimicked multiple sporadic GISTs, multiple lesions from the same patient always had concordant pathological and mutational characteristics; namely, they carried an identical KIT/PDGFRA mutation, and the mitotic index was usually high. CONCLUSIONS: The prognoses of patients with multiple sporadic GISTs were not worse than those of patients with a single lesion of the same risk under the same treatment. When it was difficult to distinguish multiple sporadic GISTs from metastatic GISTs, multiple lesions in the same patient carried different KIT/PDGFRA mutation patterns, which supported tumor multiplicity, while the concordant hypermitotic phase in multiple lesions of GISTs suggested that the tumor was metastatic.

Aberrant accumulation of Dickkopf 4 promotes tumor progression via forming the immune suppressive microenvironment in gastrointestinal stromal tumor.

BACKGROUND: Drug resistance and tumor recurrence are the major concerns in clinical practices of gastrointestinal stromal tumor (GIST), with the urgent requirement for exploring undiscovered pathways driving malignancy. To deal with these, recent studies have made many efforts to explore prognosis indicators and establish potential therapeutic targets. METHODS: Expression profiles of different risks of GISTs were described and abundant clinical evidences supported our findings in this study. Following exploration in vitro by cell experiments and verification in vivo using tumor microarray were taken to elucidate the underlying mechanism, which drove the malignancy in GIST. RESULTS: Dickkopf 4 (DKK4), as the canonical Wnt pathway antagonist, was unexpectedly and universally upregulated in high-risk GISTs, and aberrant accumulation of DKK4 was closely correlated with poor prognosis. In addition, tumor-derived DKK4 could decrease immune cells infiltration and activation in the tumor microenvironment, which decreased the antitumor effects in return. And this phenomenon was recurrent in human tumor specimens. CONCLUSIONS: Our findings identified DKK4 as a proper tumor biomarker for prognosis predicting and recurrence monitoring, and suggested a novel immune-escape mechanism driving malignancy in GIST, which might be a potential therapeutic target to improve the effects of canonical RTK therapy and combined immunotherapy.