MAP4K4 is a novel MAPK/ERK pathway regulator required for lung adenocarcinoma maintenance

Overcoming radioresistance of breast cancer cells with MAP4K4 inhibitors

Mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) has recently emerged as a promising therapeutic target in cancer. In this study, we explored the biological function of MAP4K4 in radioresistant breast cancer cells using two MAP4K4 inhibitors, namely PF06260933 and GNE-495. Radioresistant SR and MR cells were established by exposing SK-BR-3 and MCF-7 breast cancer cells to 48-70 Gy of radiation delivered at 4-5 Gy twice a week over 10 months. Surprisingly, although radioresistant cells were derived from two different subtypes of breast cancer cell lines, MAP4K4 was significantly elevated regardless of subtype. Inhibition of MAP4K4 with PF06260933 or GNE-495 selectively targeted radioresistant cells and improved the response to irradiation. Furthermore, MAP4K4 inhibitors induced apoptosis through the accumulation of DNA damage by inhibiting DNA repair systems in radioresistant cells. Notably, Inhibition of MAP4K4 suppressed the expressions of ACSL4, suggesting that MAP4K4 functioned as an upstream effector of ACSL4. This study is the first to report that MAP4K4 plays a crucial role in mediating the radioresistance of breast cancer by acting upstream of ACSL4 to enhance DNA damage response and inhibit apoptosis. We hope that our findings provide a basis for the development of new drugs targeting MAP4K4 to overcome radioresistance.

In silico identification and biological evaluation of a selective MAP4K4 inhibitor against pancreatic cancer

Inhibiting a specific target in cancer cells and reducing unwanted side effects has become a promising strategy in pancreatic cancer treatment. MAP4K4 is associated with pancreatic cancer development and correlates with poor clinical outcomes. By phosphorylating MKK4, proteins associated with cell apoptosis and survival are translated. Therefore, inhibiting MAP4K4 activity in pancreatic tumours is a new therapeutic strategy. Herein, we performed a structure-based virtual screening to identify MAP4K4 inhibitors and discovered the compound F389-0746 with a potent inhibition (IC₅₀ 120.7 nM). The results of kinase profiling revealed that F389-0746 was highly selective to MAP4K4 and less likely to cause side effects. Results of in vitro experiments showed that F389-0746 significantly suppressed cancer cell growth and viability. Results of in vivo experiments showed that F389-0746 displayed comparable tumour growth inhibition with the group treated with gemcitabine. These findings suggest that F389-0746 has promising potential to be further developed as a novel pancreatic cancer treatment.

Map4k4 is up-regulated and modulates granulosa cell injury and oxidative stress in polycystic ovary syndrome via activating JNK/c-JUN pathway: An experimental study

The regulatory mechanism on granulosa cells (GCs) oxidative injury is becoming increasingly important in polycystic ovary syndrome (PCOS) studies. Serine/threonine kinase mitogen-activated protein 4 kinase 4 (Map4k4) is linked with oxidative injury and possibly associated with premature ovarian failure and ovarian dysgenesis. Herein, we investigated the function and mechanism of Map4k4 in a PCOS rat model. A microarray from GEO database identified Map4k4 was up-regulated in the ovarian of PCOS rats, and functional enrichments suggested that oxidative stress-associated changes are involved. We verified the raised Map4k4 expression in an established PCOS rat model and also in the isolated PCOS-GCs, which were consistent with the microarray data. Map4k4 knockdown in vivo contributed to regular estrous cycle, restrained steroid concentrations and ovarian injury in PCOS rats. Both Map4k4 silencing in vivo and in vitro attenuated the PCOS-related GC oxidative stress and apoptosis. Mechanically, Map4k4 activated the JNK/c-JUN signaling pathway. Importantly, a JNK agonist restored the suppressive effects of Map4k4 silencing on PCOS-induced granulosa cell injury and oxidative stress. Besides, Map4k4 may be a target gene of miR-185-5p. In conclusion, Map4k4, a potential target of miR-185-5p, is up-regulated and induces ovarian GC oxidative injury by activating JNK/c-JUN pathway in PCOS. The Map4k4/JNK/c-JUN mechanism may provide a new idea on the treatment of PCOS.

Loss of SETD2-mediated downregulation of intracellular and exosomal miRNA-10b determines MAPK pathway activation and multidrug resistance in renal cancer

SET domain-containing 2 (SETD2) is the most frequently mutated gene among all the histone methyltransferases in clear cell renal cell carcinoma (ccRCC). Microarrays, RNA sequencing analysis and exosomes analysis of cellular supernatant were performed after transfection A498 cells with si-SETD2 or siRNA of negative control. Chromatin immunoprecipitation and Luciferase reporter assay were conducted to evaluate the interaction between SETD2 and miR-10b. Functional and drug experiments in vitro and in vivo were performed to verify the role of SETD2, miR-10b and MAP4K4. The results showed that loss of SETD2 mediated downregulation of intracellular and exosomal microRNA-10b. MAP4K4 were relevant to oncogenesis of ccRCC caused by loss of SETD2 and miR-10b. SETD2 could directly target miR-10b and regulate the expression of multidrug resistance (MDR)-1 (P-gp170) through JNK pathway, which was one of the downstream pathways of MAP4K4. The coordinated expression of SETD2/H3K36me3/miR-10b/MAPKs/JNK/MDR pathway was revealed to the progression of ccRCC.

[I lead, follow me! How cells coordinate during collective migrations.]

During development and wound healing, cells frequently move in a so-called "collective cell migration" process. The same type of migration is used by some cancer cells during metastasis formation. A powerful model to study collective cell migration is the border cell cluster in Drosophila as it allows the observation and manipulation of a collective cell migration in its normal environment. This review describes the molecular machinery used by the border cells to migrate directionally, focusing on the mechanisms used to detect and reacts to chemoattractants, and to organise the group in leader and follower cells.

Spatial tissue proteomics reveals distinct landscapes of heterogeneity in cutaneous papillomavirus-induced keratinocyte carcinomas

Infection with certain cutaneous human papillomaviruses (HPV), in conjunction with chronic ultraviolet (UV) exposure, are the major cofactors of non-melanoma skin cancer (NMSC), the most frequent cancer type worldwide. Cutaneous squamous cell carcinomas (SCCs) as well as tumors in general represent three-dimensional entities determined by both temporal and spatial constraints. Whole tissue proteomics is a straightforward approach to understand tumorigenesis in better detail, but studies focusing on different progression states toward a dedifferentiated SCC phenotype on a spatial level are rare. Here, we applied an innovative proteomic workflow on formalin-fixed, paraffin-embedded (FFPE) epithelial tumors derived from the preclinical animal model Mastomys coucha. This rodent is naturally infected with its genuine cutaneous papillomavirus and closely mimics skin carcinogenesis in the context of cutaneous HPV infections in humans. We deciphered cellular networks by comparing diverse epithelial tissues with respect to their differentiation level and infection status. Our study reveals novel regulatory proteins and pathways associated with virus-induced tumor initiation and progression of SCCs. This approach provides the basis to better comprehend the multistep process of skin carcinogenesis.

MAP4K4 and cancer: ready for the main stage?

MAP4K4 is a serine/threonine kinase that belongs to the MAP kinase family and plays a critical role in embryogenesis and cellular migration. It contains approximately 1,200 amino acids and has a molecular mass of 140 kDa. MAP4K4 is expressed in most tissues where it has been examined and its knockout is embryonic lethal due to impaired somite development. Alterations in MAP4K4 function have a central role in the development of many metabolic diseases such as atherosclerosis and type 2 diabetes, but have recently been implicated in the initiation and progression of cancer. For example, it has been shown that MAP4K4 can stimulate the proliferation and invasion of tumor cells by activating pro-proliferative pathways (such as the c-Jun N-terminal kinase [JNK] and mixed-lineage protein kinase 3 [MLK3] pathways), attenuate anti-tumor cytotoxic immune responses, and stimulate cell invasion and migration by altering cytoskeleton and actin function. Recent in vitro experiments using RNA interference-based knockdown (miR) techniques have shown that inhibition of MAP4K4 function reduces tumor proliferation, migration, and invasion, and may represent a promising therapeutic approach in many types of cancer such as pancreatic cancer, glioblastoma, and medulloblastoma, among others. Over the last few years, specific MAP4K4 inhibitors such as GNE-495 have been developed but have not yet been tested in cancer patients. However, these novel agents may be useful for cancer treatment in the future.

Abrogation of MAP4K4 protein function causes congenital anomalies in humans and zebrafish

We report 21 families displaying neurodevelopmental differences and multiple congenital anomalies while bearing a series of rare variants in mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4). MAP4K4 has been implicated in many signaling pathways including c-Jun N-terminal and RAS kinases and is currently under investigation as a druggable target for multiple disorders. Using several zebrafish models, we demonstrate that these human variants are either loss-of-function or dominant-negative alleles and show that decreasing Map4k4 activity causes developmental defects. Furthermore, MAP4K4 can restrain hyperactive RAS signaling in early embryonic stages. Together, our data demonstrate that MAP4K4 negatively regulates RAS signaling in the early embryo and that variants identified in affected humans abrogate its function, establishing MAP4K4 as a causal locus for individuals with syndromic neurodevelopmental differences.

MAP4K4 promotes ovarian cancer metastasis through diminishing ADAM10-dependent N-cadherin cleavage

Peritoneal metastasis is a key feature of advanced ovarian cancer, but the critical protein required for ovarian cancer metastasis and progression is yet to be defined. Thus, an unbiased high throughput and in-depth study is warranted to unmask the mechanism. Transcriptomic sequencing of paired primary ovarian tumors and metastases unveiled that MAP4K4, a serine/threonine kinase belongs to the Ste20 family of kinases, was highly expressed in metastatic sites. Increased MAP4K4 expression in metastasis was further validated in other independent patients, with higher MAP4K4 expression associated with poorer survival, higher level of CA125 and more advanced FIGO stage. Down regulation of MAP4K4 inhibited cancer cell adhesion, migration, and invasion. Notably, MAP4K4 was found to stabilize N-cadherin. Further results showed that MAP4K4 mediated phosphorylation of ADAM10 at Ser436 results in suppression of N-cadherin cleavage by ADAM10, leading to N-cadherin stabilization. Pharmacologic inhibition of MAP4K4 abrogated peritoneal metastases. Overall, our data reveal MAP4K4 as a significant promoter in ovarian cancer metastasis. Targeting MAP4K4 may be a potential therapeutic approach for ovarian cancer patients.

Multiple post-translational modifications ensure EGFR functionality: Potential therapeutic targets to overcome its drug-resistance mutations

Epidermal growth factor receptor (EGFR) mutation is the most common driver mutation in non-small cell lung cancer (NSCLC). The first-line therapy for advanced NSCLC patients with EGFR-sensitive mutation is the EGFR tyrosine kinase inhibitor (EGFR-TKI). However, most NSCLC patients with EGFR mutation will develop resistant mutations in EGFR-TKI therapy. With further studies, resistance mechanisms represented by EGFR-T790M mutations have revealed the impact of EGFR mutations in situ on EGFR-TKIs sensitivity. The third-generation EGFR-TKIs inhibit both EGFR-sensitive mutations and T790M mutations. The emergence of novel mutations such as EGFR-C797S and EGFR-L718Q may decrease efficacy. Searching for new targets to overcome EGFR-TKI resistance becomes a key challenge. Therefore, an in-depth understanding of the regulatory mechanisms of EGFR is essential to find novel targets to overcome drug-resistant mutations in EGFR-TKIs. EGFR, as a receptor-type tyrosine kinase, undergoes homo/heterodimerization and autophosphorylation upon binding to ligands, which activates multiple downstream signaling pathways. Interestingly, there is growing evidence that the kinase activity of EGFR is affected not only by phosphorylation but also by various post-translational modifications (PTMs, such as S-palmitoylation, S-nitrosylation, Methylation, etc.). In this review, we systematically review the effects of different protein PTMs on EGFR kinase activity and its functionality and suggest that influencing EGFR kinase activity by modulating multiple EGFR sites are potential targets to overcome EGFR-TKIs resistance mutations.

Circ004463 promotes fibroblast proliferation and collagen I synthesis by sponging miR-23b and regulating CADM3/MAP4K4 via activation of AKT/ERK pathways

Skin thickness is closely related to the appearance of human skin, such as sagging and wrinkling, which primarily depends on the level of collagen I synthesized by fibroblasts in the dermal layer. To explore the underlying genetics of the development of skin thickness, we used the indigenous Chinese Chenghua pigs, considered to have superior skin thickness, as model animals. We first performed whole transcriptome sequencing analysis to identify significant skin morphological differences between Chenghua pigs and Large White pigs and obtained some differentially expressed coding RNAs (454 mRNAs) and noncoding RNAs (612 circRNAs, 188 miRNAs, and 19 lncRNAs); moreover, some competing endogenous RNA (ceRNA) networks were constructed. Interestingly, we then identified a circRNA, namely circ0044633, which plays an important role in promoting fibroblast proliferation along with myofibroblast transition and collagen I synthesis by sponging miR-23b and regulating CADM3 and MAP4K4 expression via activation of the downstream AKT and ERK pathways in vitro. Furthermore, overexpression of circ004463 increased the mouse skin thickness and collagen I content in vivo. These results revealed a whole transcript profile of skin tissue and identified an important circ0044633-miR-23b-CADM3/MAP4K4 axis related to fibroblast proliferation and collagen I synthesis during the development of skin thickness.

tRNA derived fragments:A novel player in gene regulation and applications in cancer

The heterogeneous species of tRNA-derived fragments (tRFs) with specific biological functions was recently identified. Distinct roles of tRFs in tumor development and viral infection, mediated through transcriptional and post-transcriptional regulation, has been demonstrated. In this review, we briefly summarize the current literatures on the classification of tRFs and the effects of tRNA modification on tRF biogenesis. Moreover, we highlight the tRF repertoire of biological roles such as gene silencing, and regulation of translation, cell apoptosis, and epigenetics. We also summarize the biological roles of various tRFs in cancer development and viral infection, their potential value as diagnostic and prognostic biomarkers for different types of cancers, and their potential use in cancer therapy.

Vascular smooth muscle RhoA counteracts abdominal aortic aneurysm formation by modulating MAP4K4 activity

Whether a small GTPase RhoA plays a role in the pathology of abdominal aortic aneurysm (AAA) has not been determined. We show here that RhoA expression is reduced in human AAA lesions, compared with normal areas. Furthermore, incidence of AAA formation is increased in vascular smooth muscle cell (VSMC)-specific RhoA conditional knockout (cKO) mice. The contractility of the aortic rings and VSMCs from RhoA cKO mice is reduced, and expression of genes related to the VSMC contractility is attenuated by loss of RhoA. RhoA depletion activates the mitogen-activated protein (MAP) kinase signaling, including MAP4K4, in the aorta and VSMCs. Inhibition of MAP4K4 activity by DMX-5804 decreases AAA formation. Set, a binding protein to active RhoA, functions as an activator of MAP4K4 by sequestering PP2A, an inhibitor of MAP4K4, in the absence of RhoA. In conclusion, RhoA counteracts AAA formation through inhibition of MAP4K4 in cooperation with Set.

Low Efficacy of Genetic Tests for the Diagnosis of Primary Lymphedema Prompts Novel Insights into the Underlying Molecular Pathways

Lymphedema is a chronic inflammatory disorder caused by ineffective fluid uptake by the lymphatic system, with effects mainly on the lower limbs. Lymphedema is either primary, when caused by genetic mutations, or secondary, when it follows injury, infection, or surgery. In this study, we aim to assess to what extent the current genetic tests detect genetic variants of lymphedema, and to identify the major molecular pathways that underlie this rather unknown disease. We recruited 147 individuals with a clinical diagnosis of primary lymphedema and used established genetic tests on their blood or saliva specimens. Only 11 of these were positive, while other probands were either negative (63) or inconclusive (73). The low efficacy of such tests calls for greater insight into the underlying mechanisms to increase accuracy. For this purpose, we built a molecular pathways diagram based on a literature analysis (OMIM, Kegg, PubMed, Scopus) of candidate and diagnostic genes. The PI3K/AKT and the RAS/MAPK pathways emerged as primary candidates responsible for lymphedema diagnosis, while the Rho/ROCK pathway appeared less critical. The results of this study suggest the most important pathways involved in the pathogenesis of lymphedema, and outline the most promising diagnostic and candidate genes to diagnose this disease.

[Establishment and Preliminary Analysis of Lung Cancer Cell Line A549 with Stable MAP4 K4 Knockdown]

Objective

To analyze the effect of knocking down MAP4 K4 expression on the proliferation and migration of cancer cells, and to explore its underlining molecular mechanisms.

Methods

A stable knockdown MAP4 K4 cell line was constructed and the subcellular localization of the cells was determined with immunofluorescence, cell proliferation assay and cell migration assay. In addition, the effects of down-regulated MAP4 K4 expression were analyzed by examining the difference between the proliferation and migration of cancer cells in the knockdown group and those of the control group.

Results

MAP4 K4 was localized in focal adhesion and cell edges in A549 cells. Stable knockdown of MAP4 K4 expression induced cancer cells to grow in clusters and arrested the progression of the cell cycle and cell migration. Further analysis found that knocking down MAP4 K4 expression in A549 cells induced the accumulation of epithelial cell marker E-cadherin, and subsequently, the down-regulation of N-cadherin, a mesenchymal cell marker, thereby disrupting the "cadherin switch" and the epithelial-mesenchymal conversion. Then, the control group and the knockdown group both received the combined treatment of cisplatin at a final concentration of 5 μmol/L and paclitaxel at a final concentration of 20 nmol/L. The stably knocked down MAP4 K4 expressing cells showed significantly enhanced toxicity of chemotherapeutic drugs to cancer cells.

Conclusion

The study shows that MAP4 K4 regulates the malignant phenotypes of cancer cells and chemoresistance by regulating "cadherin switch" to promote epithelial-mesenchymal transition in A549 cells.

LncRNA ZEB1-AS1/miR-1224-5p / MAP4K4 axis regulates mitochondria-mediated HeLa cell apoptosis in persistent Chlamydia trachomatis infection

Persistent infection of Chlamydia trachomatis is thought to be responsible for the debilitating sequelae of blinding trachoma and infertility. Inhibition of host cell apoptosis is a persistent C. trachomatis infection mechanism. ZEB1-AS1 is a long non-coding RNA (lncRNA), which was up-regulated in persistent C. trachomatis infection in our previous work. In this study, we investigated the role of ZEB1-AS1 in persistent infection and the potential mechanisms. The results showed that ZEB1-AS1 was involved in the regulation of apoptosis, and targeted silencing of ZEB1-AS1 could increase the apoptosis rate of persistently infected cells. Mechanically, interference ZEB1-AS1 caused an apparent down-regulation of the Bcl-2/Bax ratio and the repression of the mitochondrial membrane potential with the remarkable release of cytochrome c, resulting in the significant elevation level of caspase-3 activation. Meanwhile, the luciferase reporter assay confirmed that ZEB1-AS1 acted as a sponge for miR-1224-5p to target MAP4K4. The regulatory effect of miR-1224-5p/MAP4K4 on persistent infection-induced antiapoptosis was regulated by ZEB1-AS1. In addition, ZEB1-AS1 inhibited the apoptosis of Chlamydia-infected cells by activating the MAPK/ERK pathway. In conclusion, we found a new molecular mechanism that the ZEB1-AS1/miR-1224-5p/MAP4K4 axis contributes to apoptosis resistance in persistent C. trachomatis infection. This work may help understand the pathogenic mechanisms of persistent C. trachomatis infection and reveal a potential therapeutic strategy for its treatment.

Transthyretin Suppressed Tumor Progression in Nonsmall Cell Lung Cancer by Inactivating MAPK/ERK Pathway

Background: Lung malignancy is a main source of disease passing all throughout the planet, whereas the transthyretin (TTR) is a specific biomarker for clinical diagnosis. However, its role in lung malignancy stays to be obscure. Materials and Methods: In the current examination, the authors made an endeavor to research impact of abnormal expression of TTR on nonsmall cell lung carcinoma (NSCLC) by overexpression or knockdown of TTR. To further explore the instruments' fundamental mechanism part of TTR in NSCLC, several signal pathways were searched and verified. To confirm the effect of TTR overexpression on tumors, in vivo experiments were conducted. Result: It was found that upregulated TTR clearly stifled cell proliferation, migration, invasion, and expanded apoptosis. Significant suppression of phosphor-extracellular signal-regulated kinase (ERK) was observed in TTR-treated NSCLC cells, implying that TTR was important for cellular progress by regulating mitogen-activated protein kinase/ERK signaling pathway. In in vivo experiment, overexpression of TTR promoted cell apoptosis and inhibited tumor growth. Conclusion: Overall, the results suggest that TTR has a potential antitumor effect in human NSCLC progression, which provides theoretical basis for the diagnosis and treatment of NSCLC. Above all, further understanding of TTR was useful for clinical care. Clinical Trial Registration Number: 2016-08.

MAP4K4 promotes pancreatic tumorigenesis via phosphorylation and activation of mixed lineage kinase 3

MAP4K4 is a Ste20 member and reported to play important roles in various pathologies, including in cancer. However, the mechanism by which MAP4K4 promotes pancreatic cancer is not fully understood. It is suggested that MAP4K4 might function as a cancer promoter via specific downstream target(s) in an organ-specific manner. Here we identified MLK3 as a direct downstream target of MAP4K4. The MAP4K4 and MLK3 associates with each other, and MAP4K4 phosphorylates MLK3 on Thr738 and increases MLK3 kinase activity and downstream signaling. The phosphorylation of MLK3 by MAP4K4 promotes pancreatic cancer cell proliferation, migration, and colony formation. Moreover, MAP4K4 is overexpressed in human pancreatic tumors and directly correlates with the disease progression. The MAP4K4-specific pharmacological inhibitor, GNE-495, impedes pancreatic cancer cell growth, migration, induces cell death, and arrests cell cycle progression. Additionally, the GNE-495 reduced the tumor burden and extended survival of the KPC mice with pancreatic cancer. The MAP4K4 inhibitor also reduced MAP4K4 protein expression, tumor stroma, and induced cell death in murine pancreatic tumors. These findings collectively suggest that MLK3 phosphorylation by MAP4K4 promotes pancreatic cancer, and therefore therapies targeting MAP4K4 might alleviate the pancreatic cancer tumor burden in patients.

Resveratrol inhibits MUC5AC expression by regulating SPDEF in lung cancer cells

BACKGROUND

MUC5AC was recently identified to play important roles in the proliferation and metastasis of malignant mucinous lung tumor cells. Resveratrol (Res), a natural compound with anticancer effects in lung cancer cells, has been reported to inhibit mucin production in airway epithelial cells. This study aimed to investigate the inhibitory effect of Res on MUC5AC expression in lung mucinous adenocarcinoma cells and the potential mechanisms.

METHODS

Mucus-producing A549 human lung carcinoma cells were used to test the effects of Res on SPDEF and MUC5AC expression. Gene and protein expression was assessed by real-time quantitative PCR (qPCR), immunofluorescence and western blotting assays. SPDEF lentivirus was used to upregulate SPDEF expression levels in mucus-producing A549 human lung carcinoma cells. Cell proliferation was assessed by Cell Counting Kit-8 (CCK-8) assay.

RESULTS

Res decreased MUC5AC expression in an SPDEF-dependent manner in mucus-producing A549 human lung carcinoma cells, and this change was accompanied by decreased ERK expression and AKT pathway activation. Moreover, SPDEF was found to be overexpressed in lung adenocarcinoma (LUAD), especially in mucinous adenocarcinoma. In-vitro functional assays showed that overexpression of SPDEF reduced the chemosensitivity of A549 cells to cisplatin (DDP). In addition, Res treatment increased A549 cell chemosensitivity to DDP by inhibiting the SPDEF-MUC5AC axis.

CONCLUSION

Our results indicate that the SPDEF-MUC5AC axis is associated with DDP sensitivity, and that Res decreases SPDEF and MUC5AC expression by inhibiting ERK and AKT signaling in A549 cells, which provides a potential pharmacotherapy for the prevention and therapeutic management of mucinous adenocarcinoma.

A 5'-tRNA halve, tiRNA-Gly promotes cell proliferation and migration via binding to RBM17 and inducing alternative splicing in papillary thyroid cancer

Background

tRNA-derived small noncoding RNAs (sncRNAs) are mainly categorized into tRNA halves (tiRNAs) and fragments (tRFs). Biological functions of tiRNAs in human solid tumor are attracting more and more attention, but researches concerning the mechanisms in tiRNAs-mediated tumorigenesis are rarely. The direct regulatory relationship between tiRNAs and splicing-related proteins remain elusive.

Methods

Papillary thyroid carcinoma (PTC) associated tRNA fragments were screened by tRNA fragments deep sequencing and validated by qRT-PCR and Northern Blot in PTC tissues. The biological function of tRNA fragments were assessed by cell counting kit, transwells and subcutaneous transplantation tumor of nude mice. For mechanistic study, tRNA fragments pull-down, RNA immunoprecipitation, Western Blot, Immunofluorescence, Immunohistochemical staining were performed.

Results

Herein, we have identified a 33 nt tiRNA-Gly significantly increases in papillary thyroid cancer (PTC) based on tRFs & tiRNAs sequencing. The ectopic expression of tiRNA-Gly promotes cell proliferation and migration, whereas down-regulation of tiRNA-Gly exhibits reverse effects. Mechanistic investigations reveal tiRNA-Gly directly bind the UHM domain of a splicing-related RNA-binding protein RBM17. The interaction with tiRNA-Gly could translocate RBM17 from cytoplasm into nucleus. In addition, tiRNA-Gly increases RBM17 protein expression via inhibiting its degradation in a ubiquitin/proteasome-dependent way. Moreover, RBM17 level in tiRNA-Gly high-expressing human PTC tissues is upregulated. In vivo mouse model shows that suppression of tiRNA-Gly decreases RBM17 expression. Importantly, tiRNA-Gly can induce exon 16 splicing of MAP4K4 mRNA leading to phosphorylation of downstream signaling pathway, which is RBM17 dependent.

Conclusions

Our study firstly illustrates tiRNA-Gly can directly bind to RBM17 and display oncogenic effect via RBM17-mediated alternative splicing. This fully novel model broadens our understanding of molecular mechanism in which tRNA fragment in tumor cells directly bind RNA binding protein and play a role in alternative splicing.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02024-3.

HGK promotes metastatic dissemination in prostate cancer

Metastasis is the process of cancer cell dissemination from primary tumors to different organs being the bone the preferred site for metastatic homing of prostate cancer (PCa) cells. Prostate tumorigenesis is a multi-stage process that ultimately tends to advance to become metastatic PCa. Once PCa patients develop skeletal metastases, they eventually succumb to the disease. Therefore, it is imperative to identify essential molecular drivers of this process to develop new therapeutic alternatives for the treatment of this devastating disease. Here, we have identified MAP4K4 as a relevant gene for metastasis in PCa. Our work shows that genetic deletion of MAP4K4 or pharmacological inhibition of its encoded kinase, HGK, inhibits metastatic PCa cells migration and clonogenic properties. Hence, MAP4K4 might promote metastasis and tumor growth. Mechanistically, our results indicate that HGK depleted cells exhibit profound differences in F-actin organization, increasing cell spreading and focal adhesion stability. Additionally, HGK depleted cells fails to respond to TNF-α stimulation and chemoattractant action. Moreover, here we show that HGK upregulation in PCa samples from TCGA and other databases correlates with a poor prognosis of the disease. Hence, we suggest that it could be used as prognostic biomarker to predict the appearance of an aggressive phenotype of PCa tumors and ultimately, the appearance of metastasis. In summary, our results highlight an essential role for HGK in the dissemination of PCa cells and its potential use as prognostic biomarker.

Sensitivity and Resistance of Oncogenic RAS-Driven Tumors to Dual MEK and ERK Inhibition

Simple Summary

Mutations in RAS-family genes frequently cause different types of human cancers. Inhibitors of the MEK (mitogen-activated protein kinase) and ERK (extracellular signal-regulated kinase) protein kinases that function downstream of RAS proteins have shown some clinical benefits when used for the treatment of these cancers, but drug resistance frequently emerges. Here we show that combined treatment with MEK and ERK inhibitors blocks the emergence of resistance to either drug alone. However, if cancer cells have already developed resistance to MEK inhibitors or to ERK inhibitors, the combined therapy is frequently ineffective. These findings imply that these inhibitors should be used together for cancer therapy. We also show that drug resistance involves complex patterns of rewiring of cellular kinase signaling networks that do not overlap between each different cancer cell line. Nonetheless, we show that MAP4K4 is required for efficient cell proliferation in several different MEK/ERK inhibitor resistant cancer cell lines, uncovering a potential new therapeutic target.

Abstract

Oncogenic mutations in RAS family genes arise frequently in metastatic human cancers. Here we developed new mouse and cellular models of oncogenic Hras^G12V-driven undifferentiated pleomorphic sarcoma metastasis and of Kras^G12D-driven pancreatic ductal adenocarcinoma metastasis. Through analyses of these cells and of human oncogenic KRAS-, NRAS- and BRAF-driven cancer cell lines we identified that resistance to single MEK inhibitor and ERK inhibitor treatments arise rapidly but combination therapy completely blocks the emergence of resistance. The prior evolution of resistance to either single agent frequently leads to resistance to dual treatment. Dual MEK inhibitor plus ERK inhibitor therapy shows anti-tumor efficacy in an Hras^G12V-driven autochthonous sarcoma model but features of drug resistance in vivo were also evident. Array-based kinome activity profiling revealed an absence of common patterns of signaling rewiring in single or double MEK and ERK inhibitor resistant cells, showing that the development of resistance to downstream signaling inhibition in oncogenic RAS-driven tumors represents a heterogeneous process. Nonetheless, in some single and double MEK and ERK inhibitor resistant cell lines we identified newly acquired drug sensitivities. These may represent additional therapeutic targets in oncogenic RAS-driven tumors and provide general proof-of-principle that therapeutic vulnerabilities of drug resistant cells can be identified.

A new function for MAP4K4 inhibitors during platelet aggregation and platelet-mediated clot retraction

Mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) is implicated in type 2 diabetes mellitus, insulin tolerance, inflammation, cancer, and atherosclerosis. We found that GNE 495 and PF 06260933 (both potent and selective MAP4K4 inhibitors) regulated human platelet activation. Immunoblotting revealed human platelets express MAP4K4, and that GNE 495 and PF 06260933 inhibited collagen-, ADP-, and thrombin-induced platelet aggregation and eventually suppressed granule release, TXA₂ generation, integrin α_IIbβ₃ activation, and clot retraction. In addition, both inhibitors elevated intracellular levels of cAMP, and coincubation with GNE 495 and aspirin or dipyridamole (a phosphodiesterase inhibitor) synergistically inhibited collagen-induced platelet aggregation and TXA₂ generation. Moreover, both inhibitors phosphorylated VASP (ser¹⁵⁷), IP3 receptor, and PKA and attenuated MAPK and PI3K/Akt/GSK3β signaling pathways. This study is the first to demonstrate that MAP4K4 inhibitors reduce thrombus formation by inhibiting platelet activation. These findings also suggest MAP4K4 be considered an emerging target protein for the treatment of thrombosis.

Down-Regulation of AHNAK2 Inhibits Cell Proliferation, Migration and Invasion Through Inactivating the MAPK Pathway in Lung Adenocarcinoma

AHNAK nucleoprotein 2 (AHNAK2) has been emerged as a crucial protein for neuroblast differentiation and cell migration, thereby involving in the development of various cancers. However, the specific molecular mechanism of AHNAK2 in lung adenocarcinoma is inconclusive. By accessing to the Oncomine dataset and GEPIA website, a higher expression level of AHNAK2 was observed in lung adenocarcinoma tissue samples. Overall survival (OS) curve plotted by Kaplan-Meier method showed that up-regulation of AHNAK2 was related with poor prognosis of lung adenocarcinoma patients. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis and western blot were conducted to examine the expression level of genes in lung adenocarcinoma cells. Through functional in vitro experiments, cell proliferation, migration and invasion were all suppressed after AHNAK2 knockdown using Cell counting kit-8 (CCK-8) assay, wound-healing and transwell analysis. Reduction of AHNAK2 decreased the apoptosis rate using flow cytometry analysis. Moreover, the key markers of MAPK pathway, p-MEK, p-ERK and p-P90RSK were decreased due to the transfection of si-AHNAK2 in A549 cells. U0126, a MEK inhibitor, showed the similar effects on MAPK-related protein levels with si-AHNAK2. To sum up, AHNAK2 is significantly increased in lung adenocarcinoma and plays a carcinogenic role by activating the MAPK signaling pathway, providing a novel insight and raising possibility for lung adenocarcinoma treatment.

Selective protection of human cardiomyocytes from anthracycline cardiotoxicity by small molecule inhibitors of MAP4K4

Given the poor track record to date of animal models for creating cardioprotective drugs, human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) have been proposed as a therapeutically relevant human platform to guide target validation and cardiac drug development. Mitogen-Activated Protein Kinase Kinase Kinase Kinase-4 (MAP4K4) is an “upstream” member of the MAPK superfamily that is implicated in human cardiac muscle cell death from oxidative stress, based on gene silencing and pharmacological inhibition in hPSC-CMs. A further role for MAP4K4 was proposed in heart muscle cell death triggered by cardiotoxic anti-cancer drugs, given its reported activation in failing human hearts with doxorubicin (DOX) cardiomyopathy, and its activation acutely by DOX in cultured cardiomyocytes. Here, we report successful protection from DOX in two independent hPSC-CM lines, using two potent, highly selective MAP4K4 inhibitors. The MAP4K4 inhibitors enhanced viability and reduced apoptosis at otherwise lethal concentrations of DOX, and preserved cardiomyocyte function, as measured by spontaneous calcium transients, at sub-maximal ones. Notably, in contrast, no intereference was seen in tumor cell killing, caspase activation, or mitochondrial membrane dissipation by DOX, in human cancer cell lines. Thus, MAP4K4 is a plausible, tractable, selective therapeutic target in DOX-induced human heart muscle cell death.

Silencing of long non-coding RNA SOX21-AS1 inhibits lung adenocarcinoma invasion and migration by impairing TSPAN8 via transcription factor GATA6

Here, we revealed the novel role of long non-coding RNAs (lncRNAs) SOX21 antisense RNA 1 (SOX21-AS1)/TSPAN8/GATA6 in progression of lung adenocarcinoma. SOX21-AS1 expression was quantified in lung adenocarcinoma tissues and cells by RT-qPCR. Then, gain- and loss-of-function experiments were conducted in lung adenocarcinoma cells. Expression of GATA6, TSPAN8 and extracellular signal-regulated kinase (ERK) signaling pathway-related genes was determined in lung adenocarcinoma cells by western blot analysis. The interaction and relationship among SOX21-AS1, GATA6 and TSPAN8 were predicted and verified respectively by RNA pull down, RIP, ChIP, and dual-luciferase reporter assays. Next, lung adenocarcinoma cell proliferation, colony formation, invasion and migration were assessed by 5-ethynyl-2'-deoxyuridine staining, colony formation assay and Transwell assay. Xenograft tumors were established in nude mice and the tumor growth was observed and recorded. SOX21-AS1 was observed to be highly expressed in lung adenocarcinoma tissues. The overexpression of SOX21-AS1, GATA6 or TSPAN8 obviously enhanced cell biological functions in lung adenocarcinoma. Meanwhile, SOX21-AS1 interacted with GATA6 which bound to TSPAN8 promoter and promoted TSPAN8 expression, which further enhanced cell colony formation, proliferation and invasion, and also activated ERK signaling pathway. Silencing of SOX21-AS1 and inhibiting its binding to GATA6 downregulate TSPAN8 and thereby exert anti-oncogenic effects in lung adenocarcinoma.

Prognostic Value of mRNA Expression of MAP4K Family in Acute Myeloid Leukemia

Background:

Despite diverse functions in diseases, the prognostic potential of the family of mitogen-activated protein kinase kinase kinase kinase genes in acute myeloid leukemia remains unknown.

Methods:

The messenger RNA expression of the MAP4K family members in 151 patients with acute myeloid leukemia was extracted from the OncoLnc database. Data for gender, age, cytogenetic, leukocyte count, CD34, FAB classification, RUNX1, and TP53 were provided by the University of California–Santa Cruz Xena platform. Kaplan-Meier analysis and Cox regression model provided an estimate of the hazard ratio with 95% confidence intervals for overall survival.

Results:

Analysis demonstrated favorable overall survival in patients with acute myeloid leukemia attributing to high expression of MAP4K3, MAP4K4, and MAP4K5 and low expression of MAP4K1 (adjusted P = .005, P = .022, P = .002, and P = .024; adjusted hazard ratio = 0.490, 95% confidence interval = 0.297-0.809, hazard ratio = 0.598, 95% confidence interval = 0.385-0.928, hazard ratio = 0.490, 95% confidence interval = 0.310-0.776, and hazard ratio = 0.615, 95% confidence interval = 0.403-0.938, respectively). Combining the high-expressing MAP4K3, MAP4K4, and MAP4K5 with the low-expressing MAP4K1 in a joint effect analysis predicted a favorable prognosis of overall survival in acute myeloid leukemia.

Conclusion:

High expression of MAP4K3, MAP4K4, and MAP4K5 combined with low expression of MAP4K1 can serve as a sensitive tool to predict favorable overall survival in patients with acute myeloid leukemia.

Targeted genomic CRISPR-Cas9 screen identifies MAP4K4 as essential for glioblastoma invasion

Among high-grade brain tumors, glioblastoma is particularly difficult to treat, in part due to its highly infiltrative nature which contributes to the malignant phenotype and high mortality in patients. In order to better understand the signaling pathways underlying glioblastoma invasion, we performed the first large-scale CRISPR-Cas9 loss of function screen specifically designed to identify genes that facilitate cell invasion. We tested 4,574 genes predicted to be involved in trafficking and motility. Using a transwell invasion assay, we discovered 33 genes essential for invasion. Of the 11 genes we selected for secondary testing using a wound healing assay, 6 demonstrated a significant decrease in migration. The strongest regulator of invasion was mitogen-activated protein kinase 4 (MAP4K4). Targeting of MAP4K4 with single guide RNAs or a MAP4K4 inhibitor reduced migration and invasion in vitro. This effect was consistent across three additional patient derived glioblastoma cell lines. Analysis of epithelial-mesenchymal transition markers in U138 cells with lack or inhibition of MAP4K4 demonstrated protein expression consistent with a non-invasive state. Importantly, MAP4K4 inhibition limited migration in a subset of human glioma organotypic slice cultures. Our results identify MAP4K4 as a novel potential therapeutic target to limit glioblastoma invasion.

Placenta-specific protein 8 promotes the proliferation of lung adenocarcinoma PC-9 cells and their tolerance to an epidermal growth factor receptor tyrosine kinase inhibitor by activating the ERK signaling pathway

Placenta-specific protein 8 (PLAC8) is a conserved protein with a molecular weight of 12.5 kDa. The specific function of this protein has not been fully elucidated, however, PLAC8 has been found to play an important tumor regulatory role in certain types of cancer, including colon, pancreatic and liver cancer. PLAC8 also participates in the regulation of the cell cycle, autophagy, epithelial-mesenchymal transition and other cellular functions, indicating its potential as a molecular target worth further investigation. The present study investigated the effect of PLAC8 on the proliferation of lung adenocarcinoma PC-9 cells and their sensitivity to gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI). It was found that the inhibition of PLAC8 expression in PC-9 cells resulted in significantly decreased proliferation, whereas overexpression of PLAC8 significantly increased the proliferation (P<0.05) of PC-9 cells. Furthermore, inhibition of PLAC8 expression resulted in decreased activity of the ERK signaling pathway, while PLAC8 overexpression increased activity of this pathway. Inhibition of the ERK signaling pathway with U0126 reversed the effects induced by inhibiting or overexpressing PLAC8 on cell proliferation. In addition, overexpression of PLAC8 significantly decreased the sensitivity of PC-9 cells to gefitinib, and this effect was reversed by U0126. Overall, these results suggest that PLAC8 is involved in the regulation of proliferation of lung adenocarcinoma PC-9 cells and impacts their sensitivity to an EGFR-TKI. Thus, PLAC8 is a potential novel target in lung adenocarcinoma for future studies.

Genome-wide profiling reveals alternative polyadenylation of mRNA in human non-small cell lung cancer

BACKGROUND

Lung cancer is the second most common cancer with an extremely poor overall survival rate. Post-transcriptional regulation of gene expression play many important roles in human cancer, and one of the potential mechanisms underlying this is alternative mRNA maturation at its 3' untranslated regions (3'-UTRs).

METHODS

Cancer tissues and paired adjacent normal lung tissues from 26 patients diagnosed with non-small cell lung cancer (NSCLC) were analyzed by in vitro transcription-sequencing alternative polyadenylation sites (IVT-SAPAS). 41,773,101 reads in average were obtained from each paired sample. A potential regulation of Cleavage Stimulation Factor Subunit 2 (CSTF2) on 3'UTR length of genes was tested in H460 cells.

RESULTS

1439 (10.26%) genes showed up-regulated expression and 1364 (9.72%) genes showed down-regulated expression in lung cancer tissue versus normal lung tissue, and shorten 3'UTR in cancer tissue was detected in cancer tissues collected from 96.2% (25/26) patients, indicating lung cancer tend to have shortened 3'UTRs of these identified genes. KEGG analysis showed 1855 genes with shorten 3'UTR were enriched in mTOR signaling, ubiquitin mediated proteolysis and RNA degradation. Knocking down CSTF2 expression in H460 cells results in 3'UTR elongation of genes that was identified to be with shortened length in cancer tissues.

CONCLUSION

Alternative polyadenylation (APA) site-switching of 3'UTRs is prevalent in NSCLC, and CSTF2 may serve as an oncogene regulates the 3'UTR length of cancer related genes in NSCLC.

C1QTNF6 as a novel biomarker regulates cellular behaviors in A549 cells and exacerbates the outcome of lung adenocarcinoma patients

C1q/tumor necrosis factor-related protein 6 (C1QTNF6) is a member of the CTRP family and implicated to cardiovascular diseases, inflammatory reaction, and adipogenesis. However, the function of C1QTNF6 in lung adenocarcinoma remains unknown. We downloaded the expression profiles of C1QTNF6 from TCGA database and Oncomine dataset in order to analyze the relationship between C1QTNF6 expression level and tumorigenesis by bioinformatics methods, such as chi-square test, Kaplan-Meier, and Cox regression analysis. In addition, we performed experiments to investigate the biological function of C1QTNF6 on cancer cells in vitro. The siRNA strategy was conducted to decrease the C1QTNF6 expression and then Cell Counting Kit-8 (CCK8) assay and wound-healing and transwell assays were to determine the proliferation, migration, and invasion. Western blot and qRT-PCR were used to confirm the expression levels. Based on the TCGA database and Oncomine dataset, we found that C1QTNF6 was over expressed in lung adenocarcinoma. The statistical data also showed that the high-regulated C1QTNF6 was related to poor prognosis in patients with lung adenocarcinoma. Moreover, the capabilities of proliferation, migration, and invasion were inhibited owing to the knockdown of C1QTNF6 in lung adenocarcinoma cells. And the phosphorylation of MEK and ERK was blocked by treated si-C1QTNF6 compared with the GAPDH. In conclusion, aberrant C1QTNF6 expression was implicated in terrible prognosis accompanying with the damage of relevant cell potential in lung adenocarcinoma. C1QTNF6 might be an independent predictor of prognosis in lung adenocarcinoma.

Long noncoding RNA CCAT2 functions as a competitive endogenous RNA to regulate FOXC1 expression by sponging miR-23b-5p in lung adenocarcinoma

Long noncoding RNA (lncRNA) may regulate the process of tumor formation. Although lncRNA CCAT2 has been identified as a key point in many diseases, its pathophysiological mechanism in lung adenocarcinoma remains unknown. We measured the expression level of CCAT2 in lung adenocarcinoma cells and normal lung epithelial cell line BEAS-2B by quantitative real-time polymerase chain reaction (qRT-PCR). As well, cell migration and proliferation were detected by transwell detection and CCK8 assay. At the same time, the new target point of CCAT2 was confirmed with bioinformatics analysis and dual-luciferase reporter assay. In addition, potential mechanisms were studied by Western blot analysis and RNA immunoprecipitation (RIP) analysis. The expression of CCAT2 was upregulated obviously in lung adenocarcinoma cells. Cell function analysis showed that upregulation of CCAT2 significantly promoted cell proliferation and migration, and reduction of CCAT2 inhibited cell migration and proliferation. In addition, CCAT2 positively regulated the expression of FOXC1 by competitive binding with miR-23b-5p. These findings indicated that CCAT2 may act as a competitive endogenous RNA (ceRNA) to regulate FOXC1 expression by competitively binding miR-23b-5p in lung adenocarcinoma.

Adaptively Weighted and Robust Mathematical Programming for the Discovery of Driver Gene Sets in Cancers

High coverage and mutual exclusivity (HCME), which are considered two combinatorial properties of mutations in a collection of driver genes in cancers, have been used to develop mathematical programming models for distinguishing cancer driver gene sets. In this paper, we summarize a weak HCME pattern to justify the description of practical mutation datasets. We then present AWRMP, a method for identifying driver gene sets through the adaptive assignment of appropriate weights to gene candidates to tune the balance between coverage and mutual exclusivity. It embeds the genetic algorithm into the subsampling strategy to provide the optimization results robust against the uncertainty and noise in the data. Using biological datasets, we show that AWRMP can identify driver gene sets that satisfy the weak HCME pattern and outperform the state-of-arts methods in terms of robustness.

m6A Reader YTHDF2 Regulates LPS-Induced Inflammatory Response

N6-methyladenosine (m6A) is an abundant mRNA modification that affects multiple biological processes, including those involved in the cell stress response and viral infection. YTH domain family 2 (YTHDF2) is an m6A-binding protein that affects the localization and stability of targeted mRNA. RNA-binding proteins (RBPs) can regulate the stability of inflammatory gene mRNA transcripts, thus participating in the regulation of inflammatory processes. As an RBP, the role of YTHDF2 in the LPS-induced inflammatory reaction has not been reported. To elucidate the function of YTHDF2 in the inflammatory response of macrophages, we first detected the expression level of YTHDF2 in RAW 264.7 cells, and found that it was upregulated after LPS stimulation. YTHDF2 knockdown significantly increased the LPS-induced IL-6, TNF-α, IL-1β, and IL-12 expression and the phosphorylation of p65, p38, and ERK1/2 in NF-κB and MAPK signaling. Moreover, the upregulated expression of TNF-α and IL-6 in cells with silenced YTHDF2 expression was downregulated by the NF-κB, p38, and ERK inhibitors. YTHDF2 depletion increased the expression and stability of MAP2K4 and MAP4K4 mRNAs. All of these results suggest that YTHDF2 knockdown increases mRNA expression levels of MAP2K4 and MAP4K4 via stabilizing the mRNA transcripts, which activate MAPK and NF-κB signaling pathways, which promote the expression of proinflammatory cytokines and aggravate the inflammatory response in LPS-stimulated RAW 264.7 cells.

Systems Biology Approach to Identify Novel Genomic Determinants for Pancreatic Cancer Pathogenesis

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy with a 5-year survival rate of <8%. Its dismal prognosis stems from inefficient therapeutic modalities owing to the lack of understanding about pancreatic cancer pathogenesis. Considering the molecular complexity and heterogeneity of PDAC, identification of novel molecular contributors involved in PDAC onset and progression using global "omics" analysis will pave the way to improved strategies for disease prevention and therapeutic targeting. Meta-analysis of multiple miRNA microarray datasets containing healthy controls (HC), chronic pancreatitis (CP) and PDAC cases, identified 13 miRNAs involved in the progression of PDAC. These miRNAs showed dysregulation in both tissue as well as blood samples, along with progressive decrease in expression from HC to CP to PDAC. Gene-miRNA interaction analysis further elucidated 5 miRNAs (29a/b, 27a, 130b and 148a) that are significantly downregulated in conjunction with concomitant upregulation of their target genes throughout PDAC progression. Among these, miRNA-29a/b targeted genes were found to be most significantly altered in comparative profiling of HC, CP and PDAC, indicating its involvement in malignant evolution. Further, pathway analysis suggested direct involvement of miRNA-29a/b in downregulating the key pathways associated with PDAC development and metastasis including focal adhesion signaling and extracellular matrix organization. Our systems biology data analysis, in combination with real-time PCR validation indicates direct functional involvement of miRNA-29a in PDAC progression and is a potential prognostic marker and therapeutic candidate for patients with progressive disease.

Chemotherapy-induced miR-141/MAP4K4 signaling suppresses progression of colorectal cancer

One of the treatment failures for colorectal cancer (CRC) is resistance to chemotherapy drugs. miRNAs have been demonstrated to be a new regulator of pathobiological processes in various tumors. While few studies have explored the specific role of miR-141 in mediating 5-fluorouracil (5-FU) sensitivity of CRC cells, the present study aimed to detect the contribution of miR-141 in 5-FU sensitivity. The CRC cells viability was measured by MTS assay and cell colony forming. The expression of miR-141 and its downstream targets were assessed by reverse transcription quantitative PCR, Western blotting, and immunohistochemistry. The functional assays were conducted using CRC cells and nude mice. At the present study, we found overexpression of miR-141 could inhibit proliferation, migration, tumor-forming and invasive potential of CRC cells in vitro and mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) was verified as a directed target of miR-141 The combination treatment of miR-141 with 5-FU, directly targetting MAP4K4, could better inhibit invasion and metastasis of CRC cells colony than either one alone. Furthermore, overexpression of miR-141, targetting MAP4K4, enhanced the effected of 5-FU and suppressed the malignant biological behaviors, in vivo Our findings showed that 5-FU inhibited malignant behavior of human CRC cells in vitro and in vivo by enhancing the efficiency of miR-141 Our data suggested that targetting the miR-141/MAP4K4 signaling pathway could be a potential molecular target that may enhance chemotherapeutic efficacy in the treatment of CRC.

Transformation-induced stress at telomeres is counteracted through changes in the telomeric proteome including SAMHD1

The authors apply telomeric chromatin analysis to identify factors that accumulate at telomeres during cellular transformation, promoting telomere replication and repair and counteracting oncogene-borne telomere replication stress.

Telomeres play crucial roles during tumorigenesis, inducing cellular senescence upon telomere shortening and extensive chromosome instability during telomere crisis. However, it has not been investigated if and how cellular transformation and oncogenic stress alter telomeric chromatin composition and function. Here, we transform human fibroblasts by consecutive transduction with vectors expressing hTERT, the SV40 early region, and activated H-RasV12. Pairwise comparisons of the telomeric proteome during different stages of transformation reveal up-regulation of proteins involved in chromatin remodeling, DNA repair, and replication at chromosome ends. Depletion of several of these proteins induces telomere fragility, indicating their roles in replication of telomeric DNA. Depletion of SAMHD1, which has reported roles in DNA resection and homology-directed repair, leads to telomere breakage events in cells deprived of the shelterin component TRF1. Thus, our analysis identifies factors, which accumulate at telomeres during cellular transformation to promote telomere replication and repair, resisting oncogene-borne telomere replication stress.

MAP4K4 controlled integrin β1 activation and c-Met endocytosis are associated with invasive behavior of medulloblastoma cells

Local tissue infiltration of Medulloblastoma (MB) tumor cells precedes metastatic disease but little is still known about intrinsic regulation of migration and invasion in these cells. We found that MAP4K4, a pro-migratory Ser/Thr kinase, is overexpressed in 30% of primary MB tumors and that increased expression is particularly associated with the frequently metastatic SHH β subtype. MAP4K4 is a driver of migration and invasion downstream of c-Met, which is transcriptionally up-regulated in SHH MB. Consistently, depletion of MAP4K4 in MB tumor cells restricts HGF-driven matrix invasion in vitro and brain tissue infiltration ex vivo. We show that these pro-migratory functions of MAP4K4 involve the activation of the integrin β-1 adhesion receptor and are associated with increased endocytic uptake. The consequent enhanced recycling of c-Met caused by MAP4K4 results in the accumulation of activated c-Met in cytosolic vesicles, which is required for sustained signaling and downstream pathway activation. The parallel increase of c-Met and MAP4K4 expression in SHH MB could predict an increased potential of these tumors to infiltrate brain tissue and cause metastatic disease. Molecular targeting of the underlying accelerated endocytosis and receptor recycling could represent a novel approach to block pro-migratory effector functions of MAP4K4 in metastatic cancers.

PEAK1, acting as a tumor promoter in colorectal cancer, is regulated by the EGFR/KRas signaling axis and miR-181d

PEAK1 is upregulated in multiple human malignancies and has been associated with tumor invasion and metastasis, but little is known about the role of PEAK1 in colorectal cancer (CRC) progression. We investigated the expression pattern, function and regulatory mechanisms of PEAK1 in CRC. Here, we found that PEAK1 is overexpressed in CRC tissues and that high PEAK1 expression predicts poor survival in colon cancer but not rectal cancer. Functionally, silencing PEAK1 inhibits cell proliferation, migration, and invasion in vitro and inhibits the growth of tumor xenografts in nude mice. Mechanistic studies revealed that PEAK1 is induced by epidermal growth factor receptor (EGFR) signaling and that PEAK1 is required for KRas-induced CRC cell growth and metastasis. Furthermore, we demonstrated that miR-181d directly targets PEAK1. Ectopic expression of miR-181d reduces the expression of PEAK1 and inhibits the growth and metastasis of CRC cells in vitro. Clinically, miR-181d is downregulated in CRC samples, and low miR-181d is correlated with poor patient survival. Our study demonstrates the importance of PEAK1 in CRC progression and suggests a potential mechanism by which increasing PEAK1 expression in CRC might be the result of EGFR/KRas signal activation and consequent miR-181d repression.