TIS21/BTG2 inhibits invadopodia formation by downregulating reactive oxygen species level in MDA-MB-231 cells

LncRNA MEG3 inhibits the proliferation and migration abilities of colorectal cancer cells by competitively suppressing MiR-31 and reducing the binding of MiR-31 to target gene SFRP1

To explore the potential mechanism of long-chain non-coding ribonucleic acid (lncRNA) maternal expression gene 3 (MEG3) in colorectal cancer (CRC). The relationship between MEG3 and miR-31 was detected by dual-luciferase assay. Quantitative polymerase chain reaction was utilized to determine the expression of MEG3 in CRC cell lines. Cell Counting Kit-8 assay was performed to detect cell proliferation. Transwell, cell scratch wound assay, and monoclonal proliferation assay were used to detect the proliferation, migration, and invasion of cells. In addition, cell motility was evaluated by detecting the expression of cellular pseudopodia protein α-actinin via immunofluorescence assay, and cell proliferation and motility were judged by determining the expressions of Ki-67, MMP2 and MMP9 via Western blotting. The effect of MEG3 and miR-31 on the development of colorectal cancer was verified by nude mouse tumor-bearing assay and HE staining. Transient transfection with MEG3 overexpression plasmid revealed that MEG3 inhibited the proliferation and motility of cells. The results of dual-luciferase assay showed that MEG3 could specifically inhibit the expression of miR-31, which inhibits the development of colorectal cancer. Transwell, cell scratch wound assay, and monoclonal proliferation experiment showed that miR-31 enhanced cell proliferation, migration and invasion. MEG3 overexpression plasmid was capable of reversing the proliferation and motility of CRC cells enhanced by miR-31. MEG3 can inhibit the proliferation and motility of CRC cells by competitively suppressing the binding of miR-31 to the target gene SFRP1, thus playing an inhibitory role in the pathogenesis of CRC.

TEM1 up-regulates MMP-2 and promotes ECM remodeling for facilitating invasion and migration of uterine sarcoma

OBJECTIVES

To explore the correlation between tumor endothelial marker 1 (TEM1) and matrix metalloproteinase 2 (MMP-2) in uterine sarcoma and their roles in the progression of uterine sarcoma.

METHODS

Uterine leiomyosarcoma (uLMS, n = 25) and uterine leiomyoma (n = 25) specimens were collected from a total of 50 patients. Immunohistochemistry assay was conducted to determine the expression of TEM1, MMP-2 and MMP-9. TEM1 over expression (hTEM1) and low expression (shRNA-TEM1) MES-SA cell lines were established as in vitro uterine sarcoma models. MMP-2 mRNA, protein expression and enzymatic activity were verified using qPCR, Western blot and gelatin zymography respectively. MMP-2 expression was downregulated using MMP-2 siRNA in hTEM1 MES-SA cells to better study the role of MMP-2. The invasive and migratory capacities of hTEM1, shRNA-TEM1, and hTEM1 treated with MMP-2 siRNA MES-SA cells were determined using transwell assays. Extracellular matrix (ECM) remodeling mediated by TEM1 was examined using cell-ECM adhesion and fluorescent gelatin-ECM degradation assays. The immunofluorescence of F-actin was examined to analyze the formation of invadopodia. Subcutaneous and intraperitoneal xenografts were established to validate the role of TEM1 in promoting uterine sarcoma metastasis.

RESULTS

TEM1 and MMP-2 were expressed in 92% (n = 23) and 88% (n = 22) of uterine leiomyosarcoma specimens, respectively. Both TEM1 and MMP-2 were highly expressed in 100% (n = 17) of high stage (III-IV) uterine leiomyosarcoma specimens. In addition, TEM1 expression was positively correlated with MMP-2 expression in uterine leiomyosarcoma. The successful establishment of in vitro uterine sarcoma models was confirmed with qPCR and Western blotting tests. TEM1 promoted the invasion and metastasis of uterine sarcoma in vivo and in vitro. MMP-2 expression and activity were up-regulated in hTEM1 cells but down-regulated in shRNA-TEM1 cells. Importantly, MMP-2 knockdown impaired the invasive and migratory capacity of hTEM1 cells. TEM1 promoted ECM remodeling by increasing cell-ECM adhesion and ECM degradation. TEM1 overexpression also induced the formation of invadopodia.

CONCLUSION

TEM1 was co-expressed and positively correlated with MMP-2 in uterine leiomyosarcoma specimens. In addition, both TEM1 and MMP-2 were associated with tumor development. TEM1 promoted uterine sarcoma progression by regulating MMP-2 activity and ECM remodeling.

Cofilin Acts as a Booster for Progression of Malignant Tumors Represented by Glioma

Cofilin, as a depolymerization factor of actin filaments, has been widely studied. Evidences show that cofilin has a role in actin structural reorganization and dynamic regulation. In recent years, several studies have demonstrated a regulatory role for cofilin in the migration and invasion mediated by cell dynamics and epithelial to mesenchymal transition (EMT)/EMT-like process, apoptosis, radiotherapy resistance, immune escape, and transcriptional dysregulation of malignant tumor cells, particularly glioma cells. On this basis, it is practical to evaluate cofilin as a biomarker for predicting tumor metastasis and prognosis. Targeting cofilin regulating kinases, Lin11, Isl-1 and Mec-3 kinases (LIM kinases/LIMKs) and their major upstream molecules inhibits tumor cell migration and invasion and targeting cofilin-mediated mitochondrial pathway induces apoptosis of tumor cells represent effective options for the development of novel anti-malignant tumor drug, especially anti-glioma drugs. This review explores the structure, general biological function, and regulation of cofilin, with an emphasis on the critical functions and prospects for clinical therapeutic applications of cofilin in malignant tumors represented by glioma.

ZEB1 directly inhibits GPX4 transcription contributing to ROS accumulation in breast cancer cells

PURPOSE

Prior studies have noted that zinc finger E-box binding homeobox 1 (ZEB1) is a master transcription regulator, affecting the expression of nearly 2000 genes in breast cancer cells, especially in the epithelial-mesenchymal transition (EMT) process. We now tested the role of ZEB1 on the oxidative stress of cancer cells and explored its possible mechanisms.

METHODS

Two human breast cancer cell lines MDA-MB-231 and MCF7 were selected for the ROS test, PCR, immunofluorescence, Western blot, chromatin immunoprecipitation assay, luciferase assay, and enzyme assay. Mouse models experiments and bioinformatics analysis were conducted to test the indicated molecules.

RESULTS

We observed ZEB1 could inhibit GPX4 transcription by binding to the E-box motifs and promote breast cancer progression by accumulating intracellular ROS. From the perspective of ROS clearance, Vitamin E enhanced GPX4 function to consume L-glutathione and eliminated excess intracellular ROS.

CONCLUSIONS

ZEB1 could not only regulate EMT, but also inhibit GPX4 transcription by binding to the E-box motif. It was important to note that the ZEB1/GPX4 axis had a therapeutic effect on breast cancer metabolism.

Invadopodia: A potential target for pancreatic cancer therapy

Dissemination of cancer cells is an intricate multistep process that represents the most deadly aspect of cancer. Cancer cells form F-actin-rich protrusions known as invadopodia to invade surrounding tissues, blood vessels and lymphatics. A number of studies have demonstrated the significant roles of invadopodia in cancer. Therefore, the specific cells and molecules involved in invadopodia activity can provide as therapeutic targets. In this review, we included a thorough overview of studies in invadopodia and discussed their functions in cancer metastasis. We then presented the specific cells and molecules involved in invadopodia activity in pancreatic cancer and analyzed their suitability to be effective therapeutic targets. Currently, drugs targeting invadopodia and relevant clinical trials are negligible. Here, we highlighted the significance of potential drugs and discussed future obstacles in implementing clinical trials. This review presents a new perspective on invadopodia-induced pancreatic cancer metastasis and may prosper the development of targeted therapeutics against pancreatic cancer.

Translational downregulation of Twist1 expression by antiproliferative gene, B-cell translocation gene 2, in the triple negative breast cancer cells

Twist1, a key transcription factor regulating epithelial–mesenchymal transition and cancer metastasis, is highly expressed in invasive cancers in contrast to the loss of BTG2^/TIS21 expression. Based on our observation that forced expression of BTG2^/TIS21 downregulated Twist1 protein expression without altering mRNA level, we investigated molecular mechanisms of the BTG2^/TIS21-inhibited Twist1 translation in the triple negative breast cancer (TNBC) cells and in vivo BTG2^/TIS21-knockout (KO) mice and human breast cancer tissues. (1) C-terminal domain of Twist1 and Box B of BTG2^/TIS21 interacted with each other, which abrogated Twist1 activity. (2) BTG2^/TIS21 inhibited translational initiation by depleting eIF4E availability via inhibiting 4EBP1 phosphorylation. (3) Expression of BTG2^/TIS21 maintained p-eIF2α that downregulates initiation of protein translation, confirmed by eIF2α-AA mutant expression and BTG2^/TIS21 knockdown in MEF cells. (4) cDNA microarray analysis revealed significantly higher expression of initiation factors-eIF2A, eIF3A, and eIF4G2-in the BTG2^/TIS21-KO mouse than that in the wild type. (5) BTG2^/TIS21-inhibited translation initiation lead to the collapse of polysome formation and the huge peak of 80s monomer in the BTG2^/TIS21 expresser, but not in the control. (6) mRNAs and protein expressions of elongation factors were also downregulated by BTG2^/TIS21 expression in TNBC cells, but much higher in both TIS21-KO mice and lymph node-positive human breast cancers. (7) BTG2^/TIS21-mediated Twist1 loss was not due to the protein degradation by ubiquitination and autophagy activation. (8) Twist1 protein level was significantly higher in various organs of TIS21-KO mice compared with that in the control, indicating the in vivo role of BTG2^/TIS21 gene in the regulation of Twist1 protein level. Altogether, the present study support our hypothesis that BTG2^/TIS21 is a promising target to combat with metastatic cancers with high level of Twist1 without BTG2^/TIS21 expression.

Invadopodia formation: An important step in matrix stiffness-regulated tumor invasion and metastasis

Highly motile and invasive abilities are symbolic features of metastatic tumor cells. Being a critical molecular event for maintaining the highly migratory and invasive capabilities of tumor cells, invadopodia formation undoubtedly determines the progression of tumor invasion and metastasis. Growing numbers of studies suggest that increased matrix stiffness, as a notable property of physical mechanics in solid tumors, participates in the regulation of tumor invasion and metastasis via different molecular mechanisms. However, to date the relevant mechanisms of matrix stiffness-induced invadopodia formation and activity in tumor cells remain largely unclear. This paper is to make a review on the structure and function of invadopodia, the stages and inductive factors of invadopodia formation, the regulatory mechanisms of matrix stiffness-induced invadopodia formation and so on, with an aim to reveal the important roles of invadopodia in matrix stiffness-regulated tumor invasion and metastasis.

PPARα-Target Gene Expression Requires TIS21/BTG2 Gene in Liver of the C57BL/6 Mice under Fasting Condition

The TIS21/BTG2/PC3 gene belongs to the antiproliferative gene (APRO) family and exhibits tumor suppressive activity. However, here we report that TIS21 controls lipid metabolism, rather than cell proliferation, under fasting condition. Using microarray analysis, whole gene expression changes were investigated in liver of TIS21 knockout (TIS21-KO) mice after 20 h fasting and compared with wild type (WT). Peroxisome proliferator-activated receptor alpha (PPARα) target gene expression was almost absent in contrast to increased lipid synthesis in the TIS21-KO mice compared to WT mice. Immunohistochemistry with hematoxylin and eosin staining revealed that lipid deposition was focal in the TIS21-KO liver as opposed to the diffuse and homogeneous pattern in the WT liver after 24 h starvation. In addition, cathepsin E expression was over 10 times higher in the TIS21-KO liver than that in the WT, as opposed to the significant reduction of thioltransferase in both adult and fetal livers. At present, we cannot account for the role of cathepsin E. However, downregulation of glutaredoxin 2 thioltransferase expression might affect hypoxic damage in the TIS21-KO liver. We suggest that the TIS21/BTG2 gene might be essential to maintain energy metabolism and reducing power in the liver under fasting condition.

Inhibition of TNFα-interacting protein α (Tipα)-associated gastric carcinogenesis by BTG2/TIS21 via downregulating cytoplasmic nucleolin expression

To understand the regulation of Helicobacter pylori (H. pylori)-associated gastric carcinogenesis, we examined the effect of B-cell translocation gene 2 (BTG2) expression on the biological activity of Tipα, an oncoprotein secreted from H. pylori. BTG2, the human ortholog of mouse TIS21 (BTG2/TIS21), has been reported to be a primary response gene that is transiently expressed in response to various stimulations. Here, we report that BTG2 is constitutively expressed in the mucous epithelium and parietal cells of the gastric gland in the stomach. Expression was increased in the mucous epithelium following H. pylori infection in contrast to its loss in human gastric adenocarcinoma. Indeed, adenoviral transduction of BTG2/TIS21 significantly inhibited Tipα activity in MKN-1 and MGT-40, human and mouse gastric cancer cells, respectively, thereby downregulating tumor necrosis factor-α (TNFα) expression and Erk1/2 phosphorylation by reducing expression of nucleolin, a Tipα receptor. Chromatin immunoprecipitation proved that BTG2/TIS21 inhibited Sp1 expression and its binding to the promoter of the nucleolin gene. In addition, BTG2/TIS21 expression significantly reduced membrane-localized nucleolin expression in cancer cells, and the loss of BTG2/TIS21 expression induced cytoplasmic nucleolin availability in gastric cancer tissues, as evidenced by immunoblotting and immunohistochemistry. Higher expression of BTG2 and lower expression of nucleolin were accompanied with better overall survival of poorly differentiated gastric cancer patients. This is the first report showing that BTG2/TIS21 inhibits nucleolin expression via Sp1 binding, which might be associated with the inhibition of H. pylori-induced carcinogenesis. We suggest that BTG2/TIS21 is a potential inhibitor of nucleolin in the cytoplasm, leading to inhibition of carcinogenesis after H. pylori infection.

A permanent window for the murine lung enables high-resolution imaging of cancer metastasis

Stable, high-resolution intravital imaging of the lung has become possible through the utilization of vacuum-stabilized imaging windows. However, this technique is extremely invasive and limited to only hours in duration. Here we describe a minimally invasive, permanently implantable window for high-resolution intravital imaging of the murine lung that allows the mouse to survive surgery, recover from anesthesia, and breathe independently. Compared to vacuum-stabilized windows, this window produces the same high-quality images without vacuum-induced artifacts; it is also less invasive, which allows imaging of the same lung tissue over a period of weeks. We further adapt the technique of microcartography for reliable relocalization of the same cells longitudinally. Using commonly employed experimental, as well as more clinically relevant, spontaneous metastasis models, we visualize all stages of metastatic seeding, including: tumor cell arrival; extravasation; growth and progression to micrometastases; as well as tumor microenvironment of metastasis function, the hallmark of hematogenous dissemination of tumor cells.

Tumor Cell Invadopodia: Invasive Protrusions that Orchestrate Metastasis

Invadopodia are a subset of invadosomes that are implicated in the integration of signals from the tumor microenvironment to support tumor cell invasion and dissemination. Recent progress has begun to define how tumor cells regulate the plasticity necessary for invadopodia to assemble and function efficiently in the different microenvironments encountered during dissemination in vivo. Exquisite mapping by many laboratories of the pathways involved in integrating diverse invadopodium initiation signals, from growth factors, to extracellular matrix (ECM) and cell-cell contact in the tumor microenvironment, has led to insight into the molecular basis of this plasticity. Here, we integrate this new information to discuss how the invadopodium is an important conductor that orchestrates tumor cell dissemination during metastasis.

Heterogeneous glioblastoma cell cross-talk promotes phenotype alterations and enhanced drug resistance

Glioblastoma multiforme is the most lethal of brain cancer, and it comprises a heterogeneous mixture of functionally distinct cancer cells that affect tumor progression. We examined the U87, U251, and U373 malignant cell lines as in vitro models to determine the impact of cellular cross-talk on their phenotypic alterations in co-cultures. These cells were also studied at the transcriptome level, to define the mechanisms of their observed mutually affected genomic stability, proliferation, invasion and resistance to temozolomide. This is the first direct demonstration of the neural and mesenchymal molecular fingerprints of U87 and U373 cells, respectively. U87-cell conditioned medium lowered the genomic stability of U373 (U251) cells, without affecting cell proliferation. In contrast, upon exposure of U87 cells to U373 (U251) conditioned medium, U87 cells showed increased genomic stability, decreased proliferation rates and increased invasion, due to a plethora of produced cytokines identified in the co-culture media. This cross talk altered the expression 264 genes in U87 cells that are associated with proliferation, inflammation, migration, and adhesion, and 221 genes in U373 cells that are associated with apoptosis, the cell cycle, cell differentiation and migration. Indirect and direct co-culturing of U87 and U373 cells showed mutually opposite effects on temozolomide resistance. In conclusion, definition of transcriptional alterations of distinct glioblastoma cells upon co-culturing provides better understanding of the mechanisms of glioblastoma heterogeneity, which will provide the basis for more informed glioma treatment in the future.

Cellular and Molecular Mechanisms of MT1-MMP-Dependent Cancer Cell Invasion

Metastasis is responsible for most cancer-associated deaths. Accumulating evidence based on 3D migration models has revealed a diversity of invasive migratory schemes reflecting the plasticity of tumor cells to switch between proteolytic and nonproteolytic modes of invasion. Yet, initial stages of localized regional tumor dissemination require proteolytic remodeling of the extracellular matrix to overcome tissue barriers. Recent data indicate that surface-exposed membrane type 1-matrix metalloproteinase (MT1-MMP), belonging to a group of membrane-anchored MMPs, plays a central role in pericellular matrix degradation during basement membrane and interstitial tissue transmigration programs. In addition, a large body of work indicates that MT1-MMP is targeted to specialized actin-rich cell protrusions termed invadopodia, which are responsible for matrix degradation. This review describes the multistep assembly of actin-based invadopodia in molecular details. Mechanisms underlying MT1-MMP traffic to invadopodia through endocytosis/recycling cycles, which are key to the invasive program of carcinoma cells, are discussed.

Inhibition of breast cancer invasion by TIS21/BTG2/Pc3-Akt1-Sp1-Nox4 pathway targeting actin nucleators, mDia genes

The mammalian homolog of Drosophila diaphanous (mDia), actin nucleator, has been known to participate in the process of invasion and metastasis of cancer cells via regulating a number of actin-related biological processes. We have previously reported that tumor suppressor TIS21(/BTG2/Pc3) (TIS21) inhibits invadopodia formation by downregulating reactive oxygen species (ROS) in MDA-MB-231 cells. We herein report that TIS21(/BTG2/Pc3) downregulates diaphanous-related formin (DRF) expression via reducing NADPH oxidase 4 (Nox4)-derived ROS generation by Akt1 activation and subsequently impairs invasion activity of the highly invasive breast cancer cells. Knockdown of Akt1 by RNA interference recovered the TIS21(/BTG2/Pc3)-inhibited F-actin remodeling and ROS generation by recovering Nox4 expression. Furthermore, Sp1-mediated Nox4 transcription was downregulated by TIS21(/BTG2/Pc3)-Akt1 signals, leading to the inhibition of cancer cell invasion via F-actin remodeling by mDia genes. To our best knowledge, this is the first study to show that TIS21(/BTG2/Pc3)-Akt1 inhibited Sp1-Nox4-ROS cascade, subsequently reducing invasion activity via inhibition of mDia family genes.

Inhibition of bladder cancer invasion by Sp1-mediated BTG2 expression via inhibition of DNA methyltransferase 1

Significantly lower endogenous expression of B-cell translocation gene 2 (BTG2) was observed in human muscle-invasive bladder cancers (MIBC) than matched normal tissues and non-muscle invasive bladder cancers (NMIBC). BTG2 expression was inversely correlated with increased expression of the DNA methyltransferases DNMT1 and DNMT3a in MIBC, but not NMIBC, suggesting a potential role for BTG2 expression in muscle invasion of bladder cancer. Over 90% of tumor tissues revealed strong methylation at CpG islands of the BTG2 gene, compared with no methylation in the normal tissues, implying epigenetic regulation of BTG2 expression in bladder carcinogenesis. By using EJ bladder cancer cells and the demethylating agent decitabine, transcription of BTG2 was shown to be up-regulated by inhibiting DNMT1 expression via modification at CpG islands. DNMT1 binding to the BTG2 gene further regulated BTG2 expression by chromatin remodeling, such as H3K9 dimethylation and H3K4 trimethylation, and Sp1 activation. Induced BTG2 expression significantly reduced EJ cell tumorigenesis and invasiveness together with induction of G2 /M arrest. These results demonstrate an important role for the BTG2(/TIS21/PC3) gene in the progression of bladder cancers, and suggest that BTG2(/TIS21/PC3) is a promising epigenetic target for prevention of muscle invasion in human bladder cancers.

Butein suppresses breast cancer growth by reducing a production of intracellular reactive oxygen species

Background

Butein has various functions in human diseases including cancer. While anti-cancer effects of butein have been revealed, it is urgent to understand a unique role of butein against cancer. In this study, we demonstrate that butein inhibition of reactive oxygen species (ROS) production results in suppression of breast cancer growth.

Methods

Different breast cancer cell lines were treated with butein and then subjected to cell viability and apoptosis assays. Butein-sensitive or -resistant breast cancer cells were injected into mammary fat pads of immunocompromised mice and then butein was injected. Breast cancer cells were categorized on the basis of butein sensitivity.

Results

Butein reduced viabilities of different breast cancer cells, while not affecting those of HER2-positive (HER2⁺) HCC-1419, SKBR-3 and HCC-2218 breast cancer cells. Butein reduction of ROS levels was correlated with apoptotic cell death. Furthermore, butein reduction of ROS level led to inhibitions of AKT phosphorylation. N-acetyl-L-cysteine (NAC), a free radical scavenger, also reduced ROS production and AKT phosphorylation, resulting in apoptotic cell death. In contrast, inhibitory effects of both butein and NAC on ROS production and AKT phosphorylation were not detected in butein-resistant HER2⁺ HCC-1419, SKBR-3 and HCC-2218 cells. In the in vivo tumor growth assays, butein inhibited tumor growth of butein-sensitive HER2⁺ BT-474 cells, while not affecting that of butein-resistant HER2⁺ HCC-1419 cells. Moreover, butein inhibition of ROS production and AKT phosphorylation was confirmed by in vivo tumor growth assays.

Conclusions

Our study first reveals that butein causes breast cancer cell death by the reduction of ROS production. Therefore, our finding provides better knowledge for butein effect on breast cancer and also suggests its treatment option.