Runx2 activates PI3K/Akt signaling via mTORC2 regulation in invasive breast cancer cells

Cecal microbiota and mammary gland microRNA signatures are related and modifiable by dietary flaxseed with implications for breast cancer risk

IMPORTANCE

Breast cancer is a leading cause of cancer mortality worldwide. There is a growing interest in using dietary approaches, including flaxseed (FS) and its oil and lignan components, to mitigate breast cancer risk. Importantly, there is recognition that pubertal processes and lifestyle, including diet, are important for breast health throughout life. Mechanisms remain incompletely understood. Our research uncovers a link between mammary gland miRNA expression and the gut microbiota in young female mice. We found that this relationship is modifiable via a dietary intervention. Using data from The Cancer Genome Atlas, we also show that the expression of miRNAs involved in these relationships is altered in breast cancer in humans. These findings highlight a role for the gut microbiome as a modulator, and thus a target, of interventions aiming at reducing breast cancer risk. They also provide foundational knowledge to explore the effects of early life interventions and mechanisms programming breast health.

Transcranial direct-current stimulation confers neuroprotection by regulating isoleucine-dependent signalling after rat cerebral ischemia-reperfusion injury

Isoleucine is a branched chain amino acid. The role of isoleucine in cerebral ischemia-reperfusion injury remains unclear. Here, we show that the concentration of isoleucine is decreased in cerebrospinal fluid in a rat model of cerebral ischemia-reperfusion injury, the rat middle cerebral artery occlusion (MCAO). To our surprise, the level of intraneuronal isoleucine is increased in an in vitro model of cerebral ischemia injury, the oxygen-glucose deprivation (OGD). We found that the increased activity of LAT1, an L-type amino acid transporter 1, leads to the elevation of intraneuronal isoleucine after OGD insult. Reducing the level of intraneuronal isoleucine promotes cell survival after cerebral ischemia-reperfusion injury, but supplementing isoleucine aggravates the neuronal damage. To understand how isoleucine promotes ischemia-induced neuronal death, we reveal that isoleucine acts upstream to reduce the expression of CBFB (core binding factor β, a transcript factor involved in cell development and growth) and that the phosphatase PTEN acts downstream of CBFB to mediate isoleucine-induced neuronal damage after OGD insult. Interestingly, we demonstrate that direct-current stimulation reduces the level of intraneuronal isoleucine in cortical cultures subjected to OGD and that transcranial direct-current stimulation (tDCS) decreases the cerebral infarct volume of MCAO rat through reducing LAT1-depencent increase of intraneuronal isoleucine. Together, these results lead us to conclude that LAT1 over activation-dependent isoleucine-CBFB-PTEN signal transduction pathway may mediate ischemic neuronal injury and that tDCS exerts its neuroprotective effect by suppressing LAT1 over activation-dependent signalling after cerebral ischemia-reperfusion injury.

Sodium alginate encapsulated iron oxide decorated with thymoquinone nanocomposite induces apoptosis in human breast cancer cells via PI3K-Akt-mTOR pathway

The present study investigated the cytotoxicity and proapoptotic properties of iron oxide-sodium-alginate-thymoquinone nanocomposites against breast cancer MDA-MB-231 cells in vitro and in silico. This study used chemical synthesis to formulate the nanocomposite. Electron microscopies such as scanning (SEM) and transmission (TEM), Fourier transform infrared (FT-IR), Ultraviolet-Visible, Photoluminescence spectroscopy, selected area (electron) diffraction (SAED), energy dispersive X-ray analysis (EDX), and X-ray diffraction studies (XRD) were used to characterize the synthesized ISAT-NCs and the average size of them was found to be 55 nm. To evaluate the cytotoxic, antiproliferative, and apoptotic potentials of ISAT-NCs on MDA-MB-231 cells, MTT assays, FACS-based cell cycle studies, annexin-V-PI staining, ELISA, and qRT-PCR were used. PI3K-Akt-mTOR receptors and thymoquinone were predicted using in-silico docking studies. Cell proliferation is reduced in MDA-MB-231 cells due to ISAT-NC cytotoxicity. As a result of FACS analysis, ISAT-NCs had nuclear damage, ROS production, and elevated annexin-V levels, which resulted in cell cycle arrest in the S phase. The ISAT-NCs in MDA-MB-231 cells were found to downregulate PI3K-Akt-mTOR regulatory pathways in the presence of inhibitors of PI3K-Akt-mTOR, showing that these regulatory pathways are involved in apoptotic cell death. We also predicted the molecular interaction between thymoquinone and PI3K-Akt-mTOR receptor proteins using in-silico docking studies which also support PI3K-Akt-mTOR signaling inhibition by ISAT-NCs in MDA-MB-231 cells. As a result of this study, we can conclude that ISAT-NCs inhibit the PI3K-Akt-mTOR pathway in breast cancer cell lines, causing apoptotic cell death.

The role of MACF1 on acute myeloid leukemia cell proliferation is involved in Runx2-targeted PI3K/Akt signaling

Acute myeloid leukemia (AML) is a type of hematologic diseases, which is related to abnormal genes. The aberrant microtubule actin cross-linking factor 1 (MACF1) is associated with progression of multiple tumors by initiating cell proliferation. Nevertheless, the function and action mechanism of MACF1 in AML cell proliferation remain mostly unknown. Our study aimed to explore the influence of MACF1 on AML cell proliferation by CCK-8 and EdU staining assays. Moreover, we aimed to explore the effect of MACF1 on downstream Runx2 and the PI3K/Akt signaling. MACF1 expression in AML patients was predicted by bioinformatics analysis. Cells were transfected with si-con, si-MACF1 or Runx2 using Lipofectamine 2000. Upregulated MACF1 was found in AML patients and predicted worse overall survival. MACF1 expression was upregulated in AML cells compared with that in hematopoietic stem and progenitor cells. MACF1 silencing reduced AML cell proliferation. Runx2 level was increased in AML cells, and decreased by silencing MACF1. Runx2 upregulation rescued MACF1 silencing-mediated inhibition of proliferation. MACF1 downregulation inhibited activation of the PI3K/Akt pathway by decreasing Runx2. Activation of the PI3K/Akt pathway abrogated the suppressive role of MACF1 downregulation in AML cell proliferation. In conclusion, MACF1 knockdown decreased AML cell proliferation by reducing Runx2 and inactivating the PI3K/Akt signaling.

Look who's TORking: mTOR-mediated integration of cell status and external signals during limb development and endochondral bone growth

The balance of cell proliferation and size is key for the control of organ development and repair. Moreover, this balance has to be coordinated within tissues and between tissues to achieve robustness in the organ's pattern and size. The tetrapod limb has been used to study these topics during development and repair, and several conserved pathways have emerged. Among them, mechanistic target of rapamycin (mTOR) signaling, despite being active in several cell types and developmental stages, is one of the least understood in limb development, perhaps because of its multiple potential roles and interactions with other pathways. In the body of this review, we have collated and integrated what is known about the role of mTOR signaling in three aspects of tetrapod limb development: 1) limb outgrowth; 2) chondrocyte differentiation after mesenchymal condensation and 3) endochondral ossification-driven longitudinal bone growth. We conclude that, given its ability to interact with the most common signaling pathways, its presence in multiple cell types, and its ability to influence cell proliferation, size and differentiation, the mTOR pathway is a critical integrator of external stimuli and internal status, coordinating developmental transitions as complex as those taking place during limb development. This suggests that the study of the signaling pathways and transcription factors involved in limb patterning, morphogenesis and growth could benefit from probing the interaction of these pathways with mTOR components.

LncRNA TEX41 regulates autophagy by increasing Runx2 expression in lung adenocarcinoma bone metastasis

OBJECTIVE

To investigate the mechanism underlying the role of TEX41 in lung adenocarcinoma (LUAD) bone metastasis (BM).

METHODS

We analyzed the biological functions and molecular mechanisms of TEX41 using bioinformatics. TEX41 and Runx2 expressions were measured in clinical tissue samples and cell lines by quantitative PCR. The effects of TEX41 on LUAD cell proliferation, migration, invasion and metastasis as well as its mechanism of action were investigated. Fluorescence in-situ hybridization (FISH) was performed to determine TEX41 and Runx2 colocalization. Subcutaneous tumor growth and BM were evaluated in nude mice by X-ray and hematoxylin and eosin (HE) staining.

RESULTS

TEX41 was dramatically increased in LUAD BM tissue, indicating a poorer prognosis in patients with LUAD and BM. TEX41 knockdown suppressed the migration and metastasis of LUAD cells, whereas TEX41 overexpression promoted these processes. Data from X-ray and HE staining showed that TEX41 supported the BM in LUAD. TEX41 overexpression induced autophagy in LUAD cells, as demonstrated by changes in autophagy markers. Results of FISH showed that TEX41 and Runx2 colocalized in the nucleus, and Runx2 expression was regulated by TEX41. The effects of TEX41 on LUAD cell migration, invasion, metastasis and autophagy were counteracted by Runx2 inhibition. Moreover, the role of TEX41 in the metastasis was partially dependent on autophagy, and phosphoinositide 3-kinase (PI3K)-AKT might be the major signaling pathway involved in TEX41-regulated autophagy.

CONCLUSION

TEX41 promotes autophagy in LUAD cells by upregulating Runx2 to mediate LUAD migration, invasion and BM.

The Role of Runx2 in Microtubule Acetylation in Bone Metastatic Breast Cancer Cells

Bone metastasis of breast cancer results in severe bone loss, fractures, and death. Crosstalk between breast cancer cells and bone resident cells promotes osteoclast activity and the release of growth factors from the bone matrix resulting in aggressive tumor growth and bone loss. We and others have shown that Runt-related transcription factor-2 (Runx2) promotes metastatic tumor growth-associated bone loss. Breast cancer cells also induce autophagy to survive metabolic stress at the metastatic site. Recently, we reported a Runx2-dependent increase in autophagy. In this study, to examine the underlying mechanisms of metastasis and tumor resistance to stress, we used a bone metastatic isogenic variant of breast cancer MDA-MB-231 cells isolated from a xenograft tumor mouse model of metastasis. Our results with immunofluorescence and biochemical approaches revealed that Runx2 promotes microtubule (MT) stability to facilitate autophagy. Stable MTs are critical for autophagosome trafficking and display increased acetylation at Lysine 40 of α-tubulin. Runx2 silencing decreases acetylated α-tubulin levels. The expression levels of HDAC6 and αTAT1, which serve to regulate the acetylation of α-tubulin, were not altered with Runx2 silencing. We found that HDAC6 interaction with α-tubulin is inhibited by Runt-related factor-2 (Runx2). We show that the expression of wild-type Runx2 can restore the acetylated polymer of MTs in Runx2 knockdown cells, while the C-terminal deletion mutant fails to rescue the polymer of MTs. Importantly, cellular stress, such as glucose starvation also increases the acetylation of α-tubulin. We found that the loss of Runx2 increases the sensitivity of breast cancer cells to MT-targeting agents. Overall, our results indicate a novel regulatory mechanism of microtubule acetylation and suggest that Runx2 and acetylated microtubules may serve as therapeutic targets for bone metastatic tumors.

miR-218-5p/RUNX2 Axis Positively Regulates Proliferation and Is Associated with Poor Prognosis in Cervical Cancer

The overexpression of miR-218-5p in cervical cancer (CC) cell lines decreases migration, invasion and proliferation. The objective was to identify target genes of miR-218-5p and the signaling pathways and cellular processes that they regulate. The relationship between the expression of miR-218-5p and RUNX2 and overall survival in CC as well as the effect of the exogenous overexpression of miR-218-5p on the level of RUNX2 were analyzed. The target gene prediction of miR-218-5p was performed in TargetScan, miRTarBase and miRDB. Predicted target genes were subjected to gene ontology (GO) and pathway enrichment analysis using the Kyoto Encyclopaedia of Genes and Genomes (KEGG). The miR-218-5p mimetic was transfected into C-33A and CaSki cells, and the miR-218-5p and RUNX2 levels were determined by RT–qPCR. Of the 118 predicted targets for miR-218-5p, 86 are involved in protein binding, and 10, including RUNX2, are involved in the upregulation of proliferation. Low miR-218-5p expression and a high level of RUNX2 are related to poor prognosis in CC. miR-218-5p overexpression is related to decreased RUNX2 expression in C-33A and CaSki cells. miR-218-5p may regulate RUNX2, and both molecules may be prognostic markers in CC.

Transcription factor Runx2 changes the expression of some matricellular proteins in metastatic breast cancer cells

BACKGROUND

Runx2 is one of the runt-related genes that are overexpressed in human cancers and contribute to metastasis. The cancer cell metastasis requires modifications of the extracellular matrix (ECM) and reduction in ECM-cell interaction. This process is performed by various enzymes and proteins secreted by cancer and surrounding cells. This study aimed to investigate the effect of the Runx2 transcription factor on the expression of matricellular proteins such as HPA1, LOX, SPARC, and OPN, which have important roles in ECM modification and ECM-cell interaction in human breast cancer. Also, the changes in their associated oncogenic pathways including Akt, Erk, FAK activities, and c-jun protein expression were investigated.

METHODS AND RESULTS

Runx2 knockdown model was created using runx2 siRNA in MDA-MB-231 human metastatic breast cancer cells. The changes in the mRNA and protein expressions of ECM proteins were shown by the qPCR and Western blotting, respectively. The results showed that there was a decrease in both mRNA and protein expressions of HPA1, SPARC, and LOX, whereas there was no change in those of OPN. Phosphorylated Akt, Erk, FAK levels, and protein expression of c-jun, however, decreased in the cells.

CONCLUSION

Our results revealed that Runx2 affected matricellular protein expression, which is important for metastasis and invasion of breast cancer. Hence, we have concluded that runx2 appears to be efficient for regulating breast cancer metastasis through an expression of matricellular proteins.

RUNX2 and LAMC2: promising pancreatic cancer biomarkers identified by an integrative data mining of pancreatic adenocarcinoma tissues

Pancreatic carcinoma (PC) is a severe disease associated with high mortality. Although strategies for cancer therapy have made great progress, outcomes of pancreatic carcinoma patients remain extremely poor. Therefore, it is urgent to find novel biomarkers and therapeutic targets. To identify biomarkers for early diagnosis and therapy, three mRNA microarray datasets and two miRNA datasets were selected, and combinative analysis was performed by GEO2R. Functional and pathway enrichment analysis were performed using DAVID database. MiRTarBase, miRWalk and Diana Tools were used to get key genes. TCGA, HPA and western blotting were used to verify diagnostic and prognostic value of key genes. By integrating mRNA and miRNA expression profiles, we identified 114 differentially expressed genes and 114 differentially expressed miRNAs, respectively. Then, three overlapping key genes, RUNX2, LAMC2 and FBXO32, were found. Their protein levels in pancreatic tissue from PC patients and normal people were analyzed by immunohistochemical staining and western blotting. RUNX2 showed a potential property to identify PC. Aberrant over-expression of LAMC2 was associated with poor prognosis of PC patients, tumor status and subtypes. In summary, our current study identified that RUNX2 and LAMC2 may be promising targets for early diagnosis and therapy of PC patients.

Bone Metastatic Breast Cancer: Advances in Cell Signaling and Autophagy Related Mechanisms

Bone metastasis is a frequent complication of breast cancer with nearly 70% of metastatic breast cancer patients developing bone metastasis during the course of their disease. The bone represents a dynamic microenvironment which provides a fertile soil for disseminated tumor cells, however, the mechanisms which regulate the interactions between a metastatic tumor and the bone microenvironment remain poorly understood. Recent studies indicate that during the metastatic process a bidirectional relationship between metastatic tumor cells and the bone microenvironment begins to develop. Metastatic cells display aberrant expression of genes typically reserved for skeletal development and alter the activity of resident cells within the bone microenvironment to promote tumor development, resulting in the severe bone loss. While transcriptional regulation of the metastatic process has been well established, recent findings from our and other research groups highlight the role of the autophagy and secretory pathways in interactions between resident and tumor cells during bone metastatic tumor growth. These reports show high levels of autophagy-related markers, regulatory factors of the autophagy pathway, and autophagy-mediated secretion of matrix metalloproteinases (MMP's), receptor activator of nuclear factor kappa B ligand (RANKL), parathyroid hormone related protein (PTHrP), as well as WNT5A in bone metastatic breast cancer cells. In this review, we discuss the recently elucidated mechanisms and their crosstalk with signaling pathways, and potential therapeutic targets for bone metastatic disease.

mTORC2 regulates hierarchical micro/nano topography-induced osteogenic differentiation via promoting cell adhesion and cytoskeletal polymerization

Surface topography acts as an irreplaceable role in the long‐term success of intraosseous implants. In this study, we prepared the hierarchical micro/nano topography using selective laser melting combined with alkali heat treatment (SLM‐AHT) and explored the underlying mechanism of SLM‐AHT surface‐elicited osteogenesis. Our results show that cells cultured on SLM‐AHT surface possess the largest number of mature FAs and exhibit a cytoskeleton reorganization compared with control groups. SLM‐AHT surface could also significantly upregulate the expression of the cell adhesion‐related molecule p‐FAK, the osteogenic differentiation‐related molecules RUNX2 and OCN as well as the mTORC2 signalling pathway key molecule Rictor. Notably, after the knocked‐down of Rictor, there were no longer significant differences in the gene expression levels of the cell adhesion‐related molecules and osteogenic differentiation‐related molecules among the three titanium surfaces, and the cells on SLM‐AHT surface failed to trigger cytoskeleton reorganization. In conclusion, the results suggest that mTORC2 can regulate the hierarchical micro/nano topography‐mediated osteogenesis via cell adhesion and cytoskeletal reorganization.

Breast tumor stiffness instructs bone metastasis via maintenance of mechanical conditioning

While the immediate and transitory response of breast cancer cells to pathological stiffness in their native microenvironment has been well explored, it remains unclear how stiffness-induced phenotypes are maintained over time after cancer cell dissemination in vivo. Here, we show that fibrotic-like matrix stiffness promotes distinct metastatic phenotypes in cancer cells, which are preserved after transition to softer microenvironments, such as bone marrow. Using differential gene expression analysis of stiffness-responsive breast cancer cells, we establish a multigenic score of mechanical conditioning (MeCo) and find that it is associated with bone metastasis in patients with breast cancer. The maintenance of mechanical conditioning is regulated by RUNX2, an osteogenic transcription factor, established driver of bone metastasis, and mitotic bookmarker that preserves chromatin accessibility at target gene loci. Using genetic and functional approaches, we demonstrate that mechanical conditioning maintenance can be simulated, repressed, or extended, with corresponding changes in bone metastatic potential.

Watson et al. demonstrate that mechanical conditioning by stiff microenvironments in breast tumors is maintained in cancer cells after dissemination to softer microenvironments, including bone marrow. They show that mechanical conditioning promotes invasion and osteolysis and establish a mechanical conditioning (MeCo) score, associated with bone metastasis in patients.

RUNX2 promotes malignant progression in gastric cancer by regulating COL1A1

BACKGROUND

Runt-related transcription factor 2 (RUNX2) is an important gene that has been implicated in the progression of human cancer. Aberrant expression of RUNX2 predicts gastric cancer (GC) metastasis. However, the molecular mechanism of RUNX2 remains unknown.

OBJECTIVE

We hypothesize that RUNX2 promotes GC metastasis by regulating the extracellular matrix component collagen type I alpha 1 (COL1A1).

METHODS

The GEPIA database and immunohistochemical staining of 60 GC tissues were used to analyse the correlations between RUNX2 or COL1A1 expression and clinicopathological features, and the Kaplan-Meier method was used to evaluate survival. RT-PCR, western blotting and immunofluorescence were used to detect RUNX2 and COL1A1 expression in GC cells. Migration and invasion assays were performed to assess the influence of RUNX2 and COL1A1 on metastasis.

RESULTS

RUNX2 and COL1A1 were highly expressed at both the gene and protein levels in GC, and patients who were positive for RUNX2 and COL1A1 had shorter survival. RUNX2 and COL1A1 expression linearly correlated with each other (r= 0.15, p< 0.01) and with clinical stage and lymph node metastasis (p< 0.05). Overexpressing RUNX2in vitro enhanced COL1A1 expression and promoted GC cell invasion and migration, whereas COL1A1 knockdown inhibited the increase in cell metastatic capacity promoted by RUNX2. In vivo, GC cells overexpressing RUNX2 promoted lung metastasis, and the downregulation of COL1A1 reduced the metastasis promoted by RUNX2.

CONCLUSIONS

RUNX2 may promote GC metastasis by regulating COL1A1. RUNX2/COL1A1 can be employed as a novel target for therapy in GC.

RUNX2 regulates leukemic cell metabolism and chemotaxis in high-risk T cell acute lymphoblastic leukemia

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy with inferior outcome compared with that of B cell ALL. Here, we show that Runt-related transcription factor 2 (RUNX2) was upregulated in high-risk T-ALL with KMT2A rearrangements (KMT2A-R) or an immature immunophenotype. In KMT2A-R cells, we identified RUNX2 as a direct target of the KMT2A chimeras, where it reciprocally bound the KMT2A promoter, establishing a regulatory feed-forward mechanism. Notably, RUNX2 was required for survival of immature and KMT2A-R T-ALL cells in vitro and in vivo. We report direct transcriptional regulation of CXCR4 signaling by RUNX2, thereby promoting chemotaxis, adhesion, and homing to medullary and extramedullary sites. RUNX2 enabled these energy-demanding processes by increasing metabolic activity in T-ALL cells through positive regulation of both glycolysis and oxidative phosphorylation. Concurrently, RUNX2 upregulation increased mitochondrial dynamics and biogenesis in T-ALL cells. Finally, as a proof of concept, we demonstrate that immature and KMT2A-R T-ALL cells were vulnerable to pharmacological targeting of the interaction between RUNX2 and its cofactor CBFβ. In conclusion, we show that RUNX2 acts as a dependency factor in high-risk subtypes of human T-ALL through concomitant regulation of tumor metabolism and leukemic cell migration.

Use of signals of positive and negative selection to distinguish cancer genes and passenger genes

A major goal of cancer genomics is to identify all genes that play critical roles in carcinogenesis. Most approaches focused on genes positively selected for mutations that drive carcinogenesis and neglected the role of negative selection. Some studies have actually concluded that negative selection has no role in cancer evolution. We have re-examined the role of negative selection in tumor evolution through the analysis of the patterns of somatic mutations affecting the coding sequences of human genes. Our analyses have confirmed that tumor suppressor genes are positively selected for inactivating mutations, oncogenes, however, were found to display signals of both negative selection for inactivating mutations and positive selection for activating mutations. Significantly, we have identified numerous human genes that show signs of strong negative selection during tumor evolution, suggesting that their functional integrity is essential for the growth and survival of tumor cells.

S100A8 and S100A9 promote endothelial cell activation through the RAGE‑mediated mammalian target of rapamycin complex 2 pathway

S100 calcium binding protein A8 (S100A8) and A9 (S100A9) belong to the S100 family of calcium-binding proteins and have important roles in inflammation. They increase endothelial cell proliferation, thereby affecting inflammation, angiogenesis and tumorigenesis. However, the mechanism of action of S100A8/9 in endothelial cells needs further study. Therefore, the present study sought to investigate the effects of S100A8/9 on the proliferation and angiogenesis of human umbilical vein endothelial cells (HUVECs) and their mechanism of action. The viability of HUVECs was determined through a Cell Counting Kit-8 assay. The effect of S100A8/9 on the proliferation of HUVECs was detected by flow cytometry. Migration was evaluated by a Transwell migration assay. Apoptosis was evaluated by Annexin V-FITC and PI staining via flow cytometry. Western blot analysis and reverse transcription-quantitative polymerase chain reaction assays were performed to evaluate the activation of the phosphatidylinositol 3-phosphate kinase (PI3K)/Akt/mTOR pathway and mTOR complex 2 (mTORC2). We previously confirmed that S100A8/9 were consistently overexpressed at 1 and 7 days post-surgery in a rabbit vein graft model, which is the period when apoptosis changes to proliferation in neointimal hyperplasia. In the present study, proliferation, viability and migration were increased after treating HUVECs with S100A8/9. S100A8/9 stimulated the PI3K/Akt/mTOR pathway and mTORC2, which was significantly suppressed by a receptor for advanced glycation end products (RAGE)-blocking antibody. Furthermore, depleting expression of RAGE or mTORC2 protein components (rapamycin-insensitive companion of mTOR) by small interfering RNA was found to reduce the cell viability, migration and angiogenesis of S100A8/9-treated HUVECs. The development of neointimal hyperplasia is a complex process initiated by damage to endothelial cells. In conclusion, S100A8/9 has an important role in intimal hyperplasia by promoting cell growth and angiogenesis via RAGE signaling and activation of mTORC2.

The role of indoleamine 2,3 dioxygenase 1 in the osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint disease and a leading cause of disability. It involves articular cartilage destruction and a whole joint inflammation. In spite of OA pathogenesis is still unclear, new studies on the OA pathophysiological aetiology and immunomodulation therapy continuously achieve significant advances with new concepts. Here, we focus on the indoleamine-2,3-dioxygenase1 (IDO1) activity in the osteoarthritis (OA), which is one of the noticeable enzymes in the synovial fluid of arthritis patients. It was recognized as an essential mediator of autoreactive B and T cell responses in rheumatoid arthritis (RA) and an interesting therapeutic target against RA. However, the role IDO1 plays in the OA pathogenesis hasn't been discussed. The new OA experimental analysis evidenced IDO1 overexpression in the synovial fluid of OA patients, and recent studies reported that IDO1 metabolites were found higher in the OA synovial fluid than RA and spondyloarthropathies (SpA) patients. Moreover, the positive relation of IDO1 metabolites with OA pain and joint stiffness has been confirmed. Thus, the IDO1 plays a pivotal role in the pathogenesis of OA. In this review, the role IDO1 plays in the OA pathogenesis has been deeply discussed. It could be a promising target in the immunotherapy of OA disease.

Delayed tooth movement in Runx2+/- mice associated with mTORC2 in stretch-induced bone formation

Runt-related transcription factor 2 (Runx2) is an essential transcription factor for osteoblast differentiation, and is activated by mechanical stress to promote osteoblast function. Cleidocranial dysplasia (CCD) is caused by mutations of RUNX2, and CCD patients exhibit malocclusion and often need orthodontic treatment. However, treatment is difficult because of impaired tooth movement, the reason of which has not been clarified. We examined the amount of experimental tooth movement in Runx2^+/− mice, the animal model of CCD, and investigated bone formation on the tension side of experimental tooth movement in vivo. Continuous stretch was conducted to bone marrow stromal cells (BMSCs) as an in vitro model of the tension side of tooth movement. Compared to wild-type littermates the Runx2^+/− mice exhibited delayed experimental tooth movement, and osteoid formation and osteocalcin (OSC) mRNA expression were impaired in osteoblasts on the tension side of tooth movement. Runx2 heterozygous deficiency delayed stretch-induced increase of DNA content in BMSCs, and also delayed and reduced stretch-induced alkaline phosphatase (ALP) activity, OSC mRNA expression, and calcium content of BMSCs in osteogenic medium. Furthermore Runx2^+/− mice exhibited delayed and suppressed expression of mammalian target of rapamycin (mTOR) and rapamycin-insensitive companion of mTOR (Rictor), essential factors of mTORC2, which is regulated by Runx2 to phosphorylate Akt to regulate cell proliferation and differentiation, in osteoblasts on the tension side of tooth movement in vivo and in vitro. Loss of half Runx2 gene dosage inhibited stretch-induced PI3K dependent mTORC2/Akt activity to promote BMSCs proliferation. Furthermore, Runx2^+/− BMSCs in osteogenic medium exhibited delayed and suppressed stretch-induced expression of mTOR and Rictor. mTORC2 regulated stretch-elevated Runx2 and ALP mRNA expression in BMSCs in osteogenic medium. We conclude that Runx2^+/− mice present a useful model of CCD patients for elucidation of the molecular mechanisms in bone remodeling during tooth movement, and that Runx2 plays a role in stretch-induced proliferation and osteogenesis in BMSCs via mTORC2 activation.

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Experimental tooth movement is delayed in Runx2^+/− mice compared with wild-type mice.

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Runx2 plays a role in stretch-induced proliferation and differentiation of BMSCs via mTORC2 activation.

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Runx2^+/− mice are useful model to clarify the mechanical stress-induced bone remodeling in CCD patients.

Targeting the C-Terminal Domain Small Phosphatase 1

The human C-terminal domain small phosphatase 1 (CTDSP1/SCP1) is a protein phosphatase with a conserved catalytic site of DXDXT/V. CTDSP1’s major activity has been identified as dephosphorylation of the 5th Ser residue of the tandem heptad repeat of the RNA polymerase II C-terminal domain (RNAP II CTD). It is also implicated in various pivotal biological activities, such as acting as a driving factor in repressor element 1 (RE-1)-silencing transcription factor (REST) complex, which silences the neuronal genes in non-neuronal cells, G1/S phase transition, and osteoblast differentiation. Recent findings have denoted that negative regulation of CTDSP1 results in suppression of cancer invasion in neuroglioma cells. Several researchers have focused on the development of regulating materials of CTDSP1, due to the significant roles it has in various biological activities. In this review, we focused on this emerging target and explored the biological significance, challenges, and opportunities in targeting CTDSP1 from a drug designing perspective.

New Function of RUNX2 in Regulating Osteoclast Differentiation via the AKT/NFATc1/CTSK Axis

Cleidocranial dysplasia is an autosomal dominant skeletal disorder resulting from RUNX2 mutations. The influence of RUNX2 mutations on osteoclastogenesis and bone resorption have not been reported. To investigate the role of RUNX2 in osteoclast, RUNX2 expression in macrophages (RAW 264.7 cells) was detected. Stable RAW 264.7 cell lines expressing wild-type RUNX2 or mutated RUNX2 (c.514delT, p.172 fs) were established, and their functions in osteoclasts were investigated. Wild-type RUNX2 promoted osteoclast differentiation, formation of F-actin ring, and bone resorption, while mutant RUNX2 attenuated the positive differentiation effect. Wild-type RUNX2 increased the expression and activity of mTORC2. Subsequently, mTORC2 specifically promoted phosphorylation of AKT at the serine 473 residue. Activated AKT improved the nuclear translocation of NFATc1 and increased the expression of downstream genes, including CTSK. Inhibition of AKT phosphorylation abrogated the osteoclast formation of wild-type macrophages, whereas constitutively activated AKT rescued the osteoclast formation of mutant macrophages. The present study suggested that RUNX2 promotes osteoclastogenesis and bone resorption through the AKT/NFATc1/CTSK axis. Mutant RUNX2 lost the function of regulating osteoclast differentiation and bone remodeling, resulting in the defective formation of the tooth eruption pathway and impaction of permanent teeth in cleidocranial dysplasia. This study, for the first time, verifies the effect of RUNX2 on osteoclast differentiation and bone resorption and provides new insight for the explanation of cleidocranial dysplasia.

Akt-targeted therapy as a promising strategy to overcome drug resistance in breast cancer - A comprehensive review from chemotherapy to immunotherapy

Breast cancer is the most frequently occurring cancer in women. Chemotherapy in combination with immunotherapy has been used to treat breast cancer. Atezolizumab targeting the protein programmed cell death-ligand (PD-L1) in combination with paclitaxel was recently approved by the Food and Drug Administration (FDA) for Triple-Negative Breast Cancer (TNBC), the most incurable type of breast cancer. However, the use of such drugs is restricted by genotype and is effective only for those TNBC patients expressing PD-L1. In addition, resistance to chemotherapy with drugs such as lapatinib, geftinib, and tamoxifen can develop. In this review, we address chemoresistance in breast cancer and discuss Akt as the master regulator of drug resistance and several oncogenic mechanisms in breast cancer. Akt not only directly interacts with the mitogen-activated protein (MAP) kinase signaling pathway to affect PD-L1 expression, but also has crosstalk with Notch and Wnt/β-catenin signaling pathways involved in cell migration and breast cancer stem cell integrity. In this review, we discuss the effects of tyrosine kinase inhibitors on Akt activation as well as the mechanism of Akt signaling in drug resistance. Akt also has a crucial role in mitochondrial metabolism and migrates into mitochondria to remodel breast cancer cell metabolism while also functioning in responses to hypoxic conditions. The Akt inhibitors ipatasertib, capivasertib, uprosertib, and MK-2206 not only suppress cancer cell proliferation and metastasis, but may also inhibit cytokine regulation and PD-L1 expression. Ipatasertib and uprosertib are undergoing clinical investigation to treat TNBC. Inhibition of Akt and its regulators can be used to control breast cancer progression and also immunosuppression, while discovery of additional compounds that target Akt and its modulators could provide solutions to resistance to chemotherapy and immunotherapy.

Runt-related transcription factor 2 influences cell adhesion-mediated drug resistance and cell proliferation in B-cell non-Hodgkin's lymphoma and multiple myeloma

Several lines of evidence show that RUNX2 as a transcription factor is closely involved in carcinogenesis in a variety of human cancers. Cell adhesion-mediated drug resistance (CAM-DR) is an important part of the mechanism underlying drug resistance in hematological tumors. In this study, we investigated the biological function of RUNX2 in B-cell Non-Hodgkin's lymphoma (B-NHL) and multiple myeloma (MM). We assessed the expression of RUNX2 in suspension and adhesion model by western blot in B-NHL and MM. Adhesion assay, flow cytometry and CCK-8 were utilized to examine the role and mechanism of RUNX2 in CAM-DR and proliferation in B-NHL and MM. RUNX2 was highly expressed in adherent B-NHL and MM cells compared to suspension cells, and knockdown the expression of RUNX2 could reverse CAM-DR. Besides, RUNX2 could promote the proliferation of B-NHL and MM cells. Furthermore, RUNX2 participated the process of CAM-DR and proliferation by regulating the AKT/GSK-3β pathway. Developing RUNX2 inhibitor may be a possible strategy for drug resistance.

SET7/9 promotes multiple malignant processes in breast cancer development via RUNX2 activation and is negatively regulated by TRIM21

Although the deregulation of lysine methyltransferase (su(var)-3-9, enhancer-of-zeste, trithorax) domain-containing protein 7/9 (SET7/9) has been identified in a variety of cancers, the potential role of SET7/9 and the molecular events in which it is involved in breast cancer remain obscure. Using the online Human Protein Atlas and GEO databases, the expression of SET7/9 was analyzed. Furthermore, we investigated the underlying mechanisms using chromatin immunoprecipitation-based deep sequencing (ChIP-seq) and quantitative ChIP assays. To explore the physiological role of SET7/9, functional analyses such as CCK-8, colony formation, and transwell assays were performed and a xenograft tumor model was generated with the human breast cancer cell lines MCF-7 and MDA-MB-231. Mass spectrometry, co-immunoprecipitation, GST pull-down, and ubiquitination assays were used to explore the mechanisms of SET7/9 function in breast cancer. We evaluated the expression of SET7/9 in different breast cancer cohorts and found that higher expression indicated worse survival times in these public databases. We demonstrated positive effects of SET7/9 on cell proliferation, migration, and invasion via the activation of Runt-related transcription factor 2 (RUNX2). We demonstrate that tripartite motif-containing protein 21 (TRIM21) physically associates with SET7/9 and functions as a major negative regulator upstream of SET7/9 through a proteasome-dependent mechanism and increased ubiquitination. Taken together, our data suggest that SET7/9 has a promoting role via the regulation of RUNX2, whereas TRIM21-mediated SET7/9 degradation acts as an anti-braking system in the progression of breast cancer.

RUNX2/CBFB modulates the response to MEK inhibitors through activation of receptor tyrosine kinases in KRAS-mutant colorectal cancer

Intrinsic and acquired resistances are major hurdles preventing the effective use of MEK inhibitors for treatment of colorectal cancer (CRC). Some 35-45% of colorectal cancers are KRAS-mutant and their treatment remains challenging as these cancers are refractory to MEK inhibitor treatment, because of feedback activation of receptor tyrosine kinases (RTKs). We reported previously that loss of ERN1 sensitizes a subset of KRAS-mutant colon cancer cells to MEK inhibition. Here we show that the loss of RUNX2 or its cofactor CBFB can confer MEK inhibitor resistance in CRC cells. Mechanistically, we find that cells with genetically ablated RUNX2 or CBFB activate multiple RTKs, which coincides with high SHP2 phosphatase activity, a phosphatase that relays signals from the cell membrane to downstream pathways governing growth and proliferation. Moreover, we show that high activity of SHP2 is causal to loss of RUNX2-induced MEK inhibitor resistance, as a small molecule SHP2 inhibitor reinstates sensitivity to MEK inhibitor in RUNX2 knockout cells. Our results reveal an unexpected role for loss of RUNX2/CBFB in regulating RTK activity in colon cancer, resulting in reduced sensitivity to MEK inhibitors.

Long Noncoding RNA (lncRNA)-Mediated Competing Endogenous RNA Networks Provide Novel Potential Biomarkers and Therapeutic Targets for Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer and has a high metastasis and reoccurrence rate. Long noncoding RNAs (lncRNAs) play an important role in CRC growth and metastasis. Recent studies revealed that lncRNAs participate in CRC progression by coordinating with microRNAs (miRNAs) and protein-coding mRNAs. LncRNAs function as competitive endogenous RNAs (ceRNAs) by competitively occupying the shared binding sequences of miRNAs, thus sequestering the miRNAs and changing the expression of their downstream target genes. Such ceRNA networks formed by lncRNA/miRNA/mRNA interactions have been found in a broad spectrum of biological processes in CRC, including liver metastasis, epithelial to mesenchymal transition (EMT), inflammation formation, and chemo-/radioresistance. In this review, we summarize typical paradigms of lncRNA-associated ceRNA networks, which are involved in the underlying molecular mechanisms of CRC initiation and progression. We comprehensively discuss the competitive crosstalk among RNA transcripts and the novel targets for CRC prognosis and therapy.

Downregulation of miR-302b is associated with poor prognosis and tumor progression of breast cancer

BACKGROUND

MicroRNAs (miRNAs) are well known to play crucial role in various types of cancers, including breast cancer (BC).

METHODS

The present study aimed to investigate the expression, clinical value, and functional role of miR-302b in BC. The expression level of miR-302b was determined by quantitative real-time polymerase chain reaction (qRT-PCR). The clinical value of miR-302b in BC prognosis was calculated via Kaplan-Meier survival analysis and Cox regression analysis. Cell experiments were applied to investigate the functional role of miR-302b in BC.

RESULTS

miR-302b was significantly downregulated in BC tissues and cell lines compared to the corresponding controls (all P < 0.01). Notably, the expression of miR-302b was significantly associated with lymph node metastasis and TNM stage (all P < 0.05). Patients with lower miR-302b expression had shorter survival time than those with higher miR-302b expression (log-rank P = 0.002). Furthermore, miR-302b expression and TNM stage were proven to be independent prognostic factors for BC. Overexpression of miR-302b inhibited BC cell proliferation, migration, and invasion in BT549 and MCF-7 cell lines, while silence of miR-302b exhibited an opposite effects on BC cells (all P < 0.05). RUNX2 was determined to be the target gene of miR-302b.

CONCLUSIONS

The present study suggests that miR-302b functions as a tumor suppressor in BC and inhibits the tumor progression of BC via targeting RUNX2. Downregulation of miR-302b might be a significant prognostic factor for poor survival in BC patients.

Rictor ablation in BMSCs inhibits bone metastasis of TM40D cells by attenuating osteolytic destruction and CAF formation

The mTOR complex 2 (mTORC2) is recognized as a promising target for breast cancer treatment. As mTORC2-specific inhibitors do not yet exist, studies into the role of mTORC2 in cancer are performed by deleting Rictor or by RNAi-mediated Rictor silencing. The purpose of this study was to explore the effects of Rictor ablation in bone mesenchymal stromal cells (BMSCs) on bone metastasis of breast cancer. First, female mice with the genotype of Prx1-Cre;Rictor^f/f (hereafter RiCKO) or Rictor^f/f (as control) were injected intratibially with cells of the breast cancer cell line (TM40D) at 4 months of age. Three weeks later, osteolytic bone destruction was detected in metastatic legs by X-ray and micro-CT. We found that Rictor ablation in BMSCs inhibited TM40D-induced osteolytic bone destruction and resulted in greater bone volume maintenance in vivo. Lower CTX-I serum level, a decreased number of TRAP+ osteoclasts and lower Cathepsin-K expression observed at the tumor-bone interface indicated that osteoclastogenesis was inhibited in RiCKO mice. Additionally, co-culture experiments confirmed that Rictor deletion in BMSCs diminished osteoclast differentiation partly via down regulation of RANKL expression. Furthermore, Rictor deficiency was found to reduce the transition of BMSCs to CAFs coupled with decreased secretion of cytokines (IL-6, RANKL, TGFβ), which resulted in lower chemotaxis and less proliferation in TM40D cells. These results suggest that Rictor ablation in BMSCs plays dual roles in breast cancer bone metastasis: (1) repression of osteolytic bone destruction; (2) inhibition of tumor growth.

MicroRNA-153 inhibits cell proliferation, migration, invasion and epithelial-mesenchymal transition in breast cancer via direct targeting of RUNX2

A number of microRNAs (miRNAs) are involved in the development and malignant progression of numerous types of human cancer including breast cancer. The underlying regulatory mechanism of miRNA-153 (miR-153) in breast cancer progression remains largely unknown. The present study demonstrated that miR-153 expression levels were significantly reduced in breast cancer tissue samples and cell lines, compared with adjacent healthy tissue samples and normal human breast cell line MCF-10A. In addition, low miR-153 expression was associated with advanced clinical staging and metastasis in patients with breast cancer. However, no association with age, subtype or differentiation was identified. Furthermore, patients with breast cancer with low miR-153 expression had poor prognosis, compared with patients with breast cancer with high miR-153 expression. Overexpression of miR-153 reduced proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) in breast cancer SK-BR-3 and BT-549 cells. Runt-related transcription factor 2 (RUNX2), which was revealed to be significantly upregulated in breast cancer, was verified as a target gene of miR-153 in SK-BR-3 and BT-549 cells by luciferase reporter gene assay. High RUNX2 expression was associated with advanced clinical staging as well as distant and lymph node metastasis in patients with breast cancer. However, no association with age, subtype or differentiation was identified. Additionally, an inverse correlation between miR-153 and RUNX2 mRNA expression levels was observed in breast cancer tissues. RUNX2 overexpression reduced the suppressive effects of miR-153 on the proliferation, migration, invasion and EMT of SK-BR-3 and BT-549 cells. The present study indicated that miR-153 may serve a role in breast tumor growth and metastasis via direct targeting of RUNX2. The miR-153/RUNX2 axis may be used as a potential therapeutic target in breast cancer treatment.

High long non-coding RNA NORAD expression predicts poor prognosis and promotes breast cancer progression by regulating TGF-β pathway

Background

To investigate the expression and significance of long noncoding RNA NORAD (lncRNA-NORAD) in breast cancer.

Methods

Q-PCR was adopted to detect the mRNA expression of lncRNA-NORAD in breast cancer and adjacent tissues, survival analysis to compare the low-expression groups with the Kaplan-Meier method. Knockout of lncRNA-NORAD was adopted to observe the effects on the cell proliferation, migration and invasion of breast cancer in vitro and in vivo. The TGF-β/RUNX2 signaling pathway was observed by Western blot after the knockout of lncRNA-NORAD.

Results

Increased expression of lncRNA-NORAD in breast cancer tissues promotes proliferation, invasion and migration of breast cancer cells and correlated with worse prognosis. LncRNA-NORAD activated TGF-β/RUNX2 signaling pathway in breast cancer cells.

Conclusions

These results strongly suggested that lncRNA-NORAD might play an important role in breast cancer progression and potentially be a new therapeutic target.

miR-218 overexpression suppresses tumorigenesis of papillary thyroid cancer via inactivation of PTEN/PI3K/AKT pathway by targeting Runx2

Background

It was previously reported that downregulation of miR-218 promoted thyroid cancer cell invasion, migration, and proliferation. However, the biological functions of miR-218 and its possible regulatory mechanisms in papillary thyroid cancer (PTC) cells are still elusive.

Materials and methods

The expression levels of miR-218 and Runx2 in PTC tissues and cells were determined by quantitative real-time PCR (qRT-PCR) and Western blot. The effects of miR-218 overexpression on cell viability, invasion, apoptosis, and PTEN/PI3K/AKT pathway in PTC cells were evaluated by cell counting kit-8 assay, Transwell invasion assay, flow cytometry assay, and Western blot, respectively. Luciferase reporter assay and qRT-PCR were performed to identify the target of miR-218. Xenograft tumor experiment was performed to confirm the biological roles of miR-218 and its potential mechanisms in vivo.

Results

miR-218 expression was downregulated and Runx2 expression was upregulated in PTC tissues and cells. Overexpression of miR-218 suppressed viability and invasion, and induced apoptosis of PTC cells in vitro, while Runx2 overexpression greatly abolished these effects. miR-218 overexpression inactivated the PTEN/PI3K/AKT pathway, which was abated by Runx2 upregulation. Additionally, Runx2 was validated to be a direct target of miR-218. Moreover, enforced expression of miR-218 inhibited tumor growth and Runx2 expression, and blocked PTEN/PI3K/AKT pathway in vivo.

Conclusion

miR-218 overexpression suppresses the tumorigenesis of PTC via downregulating PTEN/PI3K/AKT pathway by targeting Runx2, which indicates that miR-218 may be a potential therapeutic target for human PTC.

Antitumor efficacy of the Runx2-dendritic cell vaccine in triple-negative breast cancer in vitro

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with a poor prognosis and limited effective treatment. The rise in immunotherapeutic strategies prompted the establishment of a genetic vaccine against TNBC in vitro using a possible biological marker of TNBC. In the present study, different detection methods were used to evaluate the distribution and expression of runt-associated transcription factor 2 (Runx2) in various breast cancer cell lines. Following the development of the Runx2-dendritic cell (DC) vaccine using a lentivirus, the transfection efficacy was recorded. The T lymphocytes co-cultured with the vaccine were collected to assess the antitumor potency. Increased levels of Runx2 were expressed in breast cancer cells; however, different breast cancer cell lines expressed various levels of Runx2. Runx2 demonstrated particularly high expression in TNBC cells, compared with non-TNBC cells. A Runx2 lentivirus transfection system was successfully engineered, and Runx2 was transduced into dendritic cells whilst maintaining stable expression. The sustained and stable cytotoxic T cells induced in the transfected group had higher and more specific antitumor efficacy against TNBC, compared with the other cell lines. Runx2 may be a novel target for TNBC treatment. The Runx2-DC vaccine may induce specific and efficient antitumor effects in TNBC in vitro.

RICTOR gene amplification is correlated with metastasis and therapeutic resistance in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is characterized by its aggressive behavior, metastasis and lack of targeted therapies. Herein, we discuss the clinical, histopathological and genetic profile of a woman diagnosed with TNBC. Since the patient had no durable response to chemotherapy, a genetic profiling was carried out. Next-generation sequencing analysis of 592 genes showed a missense mutation, p.E545A in PIK3CA, thus the patient was started on the mTOR inhibitor everolimus, in combination with exemestane, which controlled her pain; however, the disease progressed aggressively. More importantly, next-generation sequencing analysis showed a RICTOR gene amplification (eight copies) suggesting that RICTOR promotes the genesis of TNBC. We conclude that determining regulators of RICTOR and furthermore, their inhibitors might decrease cancer cells proliferation rate in patients with TNBC.

Breast cancer cells obtain an osteomimetic feature via epithelial-mesenchymal transition that have undergone BMP2/RUNX2 signaling pathway induction

Bone is one of the most common organs of breast cancer metastasis. Cancer cells that mimic osteoblasts by expressing bone matrix proteins and factors have a higher likelihood of metastasizing to bone. However, the molecular mechanisms of osteomimicry formation of cancer cells remain undefined. Herein, we identified a set of bone-related genes (BRGs) that are ectopically co-expressed in primary breast cancer tissues and determined that osteomimetic feature is obtained due to the osteoblast-like transformation of epithelial breast cancer cells that have undergone epithelial-mesenchymal transition (EMT) followed by bone morphogenetic protein-2 (BMP2) stimulation. Furthermore, we demonstrated that breast cancer cells that transformed into osteoblast-like cells with high expression of BRGs showed enhanced chemotaxis, adhesion, proliferation and multidrug resistance in an osteoblast-mimic bone microenvironment in vitro. During these processes, runt-related transcription factor 2 (RUNX2) functioned as a master mediator by suppressing or activating the transcription of BRGs that underlie the dynamic antagonism between the TGF-β/SMAD and BMP/SMAD signaling pathways in breast cancer cells. Our findings suggest a novel mechanism of osteomimicry formation that arises in primary breast tumors, which may explain the propensity of breast cancer to metastasize to the skeleton and contribute to potential strategies for predicting and targeting breast cancer bone metastasis and multidrug resistance.

Hyperactive mTOR and MNK1 phosphorylation of eIF4E confer tamoxifen resistance and estrogen independence through selective mRNA translation reprogramming

Geter et al. show that tamoxifen resistance involves selective mRNA translational reprogramming to an anti-estrogen state by Runx2 and other mRNAs. Tamoxifen-resistant translational reprogramming is shown to be mediated by increased expression of eIF4E and its increased availability by hyperactive mTOR and to require phosphorylation of eIF4E at Ser209 by increased MNK activity.

The majority of breast cancers expresses the estrogen receptor (ER⁺) and is treated with anti-estrogen therapies, particularly tamoxifen in premenopausal women. However, tamoxifen resistance is responsible for a large proportion of breast cancer deaths. Using small molecule inhibitors, phospho-mimetic proteins, tamoxifen-sensitive and tamoxifen-resistant breast cancer cells, a tamoxifen-resistant patient-derived xenograft model, patient tumor tissues, and genome-wide transcription and translation studies, we show that tamoxifen resistance involves selective mRNA translational reprogramming to an anti-estrogen state by Runx2 and other mRNAs. Tamoxifen-resistant translational reprogramming is shown to be mediated by increased expression of eIF4E and its increased availability by hyperactive mTOR and to require phosphorylation of eIF4E at Ser209 by increased MNK activity. Resensitization to tamoxifen is restored only by reducing eIF4E expression or mTOR activity and also blocking MNK1 phosphorylation of eIF4E. mRNAs specifically translationally up-regulated with tamoxifen resistance include Runx2, which inhibits ER signaling and estrogen responses and promotes breast cancer metastasis. Silencing Runx2 significantly restores tamoxifen sensitivity. Tamoxifen-resistant but not tamoxifen-sensitive patient ER⁺ breast cancer specimens also demonstrate strongly increased MNK phosphorylation of eIF4E. eIF4E levels, availability, and phosphorylation therefore promote tamoxifen resistance in ER⁺ breast cancer through selective mRNA translational reprogramming

Genome-Wide Transcriptome Analysis of Estrogen Receptor-Positive and Human Epithelial Growth Factor Receptor 2-Positive Breast Cancers by Ribonucleic Acid Sequencing

AIM

The aim is to identify complex pathogenesis of breast cancer subtypes and disclose the whole landscape of altered transcriptional activities in these cancers.

METHODS

We downloaded raw expression data from public database, and performed transcriptome analysis of 8 estrogen receptor-positive (ER+) breast cancer tissue samples, 8 human epithelial growth factor receptor 2-positive (HER2+) breast cancer tissue samples, and 3 normal breast tissues by identification, functional annotation, and prediction of upstream regulators and cell-surface biomarkers of differentially expressed genes (DEGs).

RESULTS

We identified over 5,000 DEGs in each of ER+ and HER2+ breast cancers compared to normal tissues. Functional enrichment analysis of shared DEGs indicated significant changes in the regulation of immune -systems in the 2 subtypes. We further identified 1,871 DEGs between the 2 subtypes and disclosed great tumor heterogeneity. We identified 533 shared upregulated genes and predicted 17 upstream transcription factors, as well as identified differentially expressed cell-surface biomarkers for distinguishing our ER+ and HER2+ breast cancers. Further analysis also highlighted the limitation of the usage of HER2 alone in breast cancer classification.

CONCLUSION

Our findings in ER+ and HER2+ breast cancers provided novel insights into heterogeneous transcriptional activities underlying complex mechanisms of oncogenesis in breast cancers.

Cell Migration and Bone Formation from Mesenchymal Stem Cell Spheroids in Alginate Hydrogels Are Regulated by Adhesive Ligand Density

The adhesion and migration of cells entrapped in engineered materials is regulated by available adhesive ligands. Although mesenchymal stem cell (MSC) spheroids injected into damaged tissues promote repair, their transplantation in biomaterials which regulate cell migration from the aggregate may further enhance their therapeutic potential. Alginate hydrogels were modified with Arginine-Glycine-Aspartic acid (RGD) at increasing concentrations, and osteogenically induced human MSC spheroids were entrapped to assess cell migration, survival, and differentiation. Cell migration was greater from MSC spheroids in alginate modified with low RGD levels, while the osteogenic potential was higher for spheroids entrapped in unmodified or high RGD density gels in vitro. Upon ectopic implantation, microCT and immunohistochemistry revealed extensive osteogenesis in unmodified and high RGD density gels compared to low RGD density gels. These data suggest that restriction of MSC migration from spheroids correlates with enhanced spheroid osteogenic potential, representing a novel tool for bone tissue engineering.

Targeting protein quality control pathways in breast cancer

The efficient production, folding, and secretion of proteins is critical for cancer cell survival. However, cancer cells thrive under stress conditions that damage proteins, so many cancer cells overexpress molecular chaperones that facilitate protein folding and target misfolded proteins for degradation via the ubiquitin-proteasome or autophagy pathway. Stress response pathway induction is also important for cancer cell survival. Indeed, validated targets for anti-cancer treatments include molecular chaperones, components of the unfolded protein response, the ubiquitin-proteasome system, and autophagy. We will focus on links between breast cancer and these processes, as well as the development of drug resistance, relapse, and treatment.

Runt-related transcription factor 2 (RUNX2) inhibits apoptosis of intestinal epithelial cells in Crohn's disease

Apoptosis in intestinal epithelial cells (IECs) prevents the development of Crohn's disease (CD), a type of inflammatory bowel disease (IBD). Runt-related transcription factor 2 (Runx2) inhibits apoptosis in osteosarcoma-derived U2OS cells via down-regulating the transcriptional activity of p53. However, the expression and function of Runx2 in CD remain unclear. In this study, Runx2 protein levels were decreased in the intestinal epithelial cells (IECs) of CD patients and in a mouse 2, 4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis model; in contrast, the expression levels of p53 and Bax, a p53-target gene, were increased. In a TNF-α-treated HT29 cell colitis model, the down-regulation of Runx2 was accompanied by the up-regulation of apoptotic markers, including cleaved caspase-3 and Bax. Furthermore, Runx2 overexpression effectively decreased TNF-α-induced Bax and cleaved caspase-3 expression levels. In conclusion, our data indicated that Runx2 might protect IECs from apoptosis in CD, thus revealing a novel molecular target for treating CD.

mTORC2/AKT/HSF1/HuR constitute a feed-forward loop regulating Rictor expression and tumor growth in glioblastoma

Overexpression of Rictor has been demonstrated to result in increased mTORC2 nucleation and activity leading to tumor growth and increased invasive characteristics in glioblastoma multiforme (GBM). However the mechanisms regulating Rictor expression in these tumors is not clearly understood. In this report, we demonstrate that Rictor is regulated at the level of mRNA translation via HSF1-induced HuR activity. HuR is shown to directly bind the 3′ UTR of the Rictor transcript and enhance translational efficiency. Moreover, we demonstrate that mTORC2/AKT signaling activates HSF1 resulting in a feed-forward cascade in which continued mTORC2 activity is able to drive Rictor expression. RNAi-mediated blockade of AKT, HSF1 or HuR is sufficient to downregulate Rictor and inhibit GBM growth and invasive characteristics in vitro and suppresses xenograft growth in mice. Modulation of AKT or HSF1 activity via the ectopic expression of mutant alleles support the ability of AKT to activate HSF1 and demonstrate continued HSF1/HuR/Rictor signaling in the context of AKT knockdown. We further show that constitutive overexpression of HuR is able to maintain Rictor expression under conditions of AKT or HSF1 loss. The expression of these components is also examined in patient GBM samples and correlative associations between the relative expression of these factors support the presence of these signaling relationships in GBM. These data support a role for a feed-forward loop mechanism by which mTORC2 activity stimulates Rictor translational efficiency via an AKT/HSF1/HuR signaling cascade resulting in enhanced mTORC2 activity in these tumors.

Embryonic transcription factor SOX9 drives breast cancer endocrine resistance

The estrogen receptor (ER) drives the growth of most luminal breast cancers and is the primary target of endocrine therapy. Although ER blockade with drugs such as tamoxifen is very effective, a major clinical limitation is the development of endocrine resistance especially in the setting of metastatic disease. Preclinical and clinical observations suggest that even following the development of endocrine resistance, ER signaling continues to exert a pivotal role in tumor progression in the majority of cases. Through the analysis of the ER cistrome in tamoxifen-resistant breast cancer cells, we have uncovered a role for an RUNX2-ER complex that stimulates the transcription of a set of genes, including most notably the stem cell factor SOX9, that promote proliferation and a metastatic phenotype. We show that up-regulation of SOX9 is sufficient to cause relative endocrine resistance. The gain of SOX9 as an ER-regulated gene associated with tamoxifen resistance was validated in a unique set of clinical samples supporting the need for the development of improved ER antagonists.

The role of Runx2 in facilitating autophagy in metastatic breast cancer cells

Breast cancer metastases cause significant patient mortality. During metastases, cancer cells use autophagy, a catabolic process to recycle nutrients via lysosomal degradation, to overcome nutritional stress for their survival. The Runt-related transcription factor, Runx2, promotes cell survival under metabolic stress, and regulates breast cancer progression and bone metastases. Here, we identify that Runx2 enhances autophagy in metastatic breast cancer cells. We defined Runx2 function in cellular autophagy by monitoring microtubule-associated protein light chain (LC3B-II) levels, an autophagy-specific marker. The electron and confocal microscopic analyses were utilized to identify alterations in autophagic vesicles. The Runx2 knockdown cells accumulate LC3B-II protein and autophagic vesicles due to reduced turnover. Interestingly, Runx2 promotes autophagy by enhancing trafficking of LC3B vesicles. Our mechanistic studies revealed that Runx2 promotes autophagy by increasing acetylation of α-tubulin sub-units of microtubules. Inhibiting autophagy decreased cell adhesion and survival of Runx2 knockdown cells. Furthermore, analysis of LC3B protein in clinical breast cancer specimens and tumor xenografts revealed significant association between high Runx2 and low LC3B protein levels. Our studies reveal a novel regulatory mechanism of autophagy via Runx2 and provide molecular insights into the role of autophagy in metastatic cancer cells.

Runx2 alleviates high glucose-suppressed osteogenic differentiation via PI3K/AKT/GSK3β/β-catenin pathway

Hyperglycemia is one of the most important pathogenesis of diabetic osteopathy. Several lines of studies indicate Runx2 plays a critical role in the process of osteogenic differentiation. However, little studies have analyzed the effect of Runx2 on osteoblast differentiation of rat bone mesenchymal stem cells (rBMSCs) in high-glucose condition. In this study, the effect of Runx2 on osteoblast differentiation in high-glucose condition was evaluated by the expression of osteogenesis-related maker including Runx2, ALP, OC, and OPN, as well as ALP staining, ALP activity, and Alizarin red S staining. Western blot analysis was performed to detect the protein expression levels of p-AKT, AKT, p-GSK3β, GSK3β, and β-catenin. Immunofluorescence staining analysis was performed to detect subcellular localization of β-catenin. Our results revealed that high glucose significantly inhibited osteogenic differentiation, hyperosmolarity did not cause a suppression. In addition, Runx2 could upregulate the expression of osteogenic-related genes and increase matrix mineralization, while applying 10 µM PI3K/AKT inhibitor LY294002 abolished the beneficial effect. Collectively, these results indicate that Runx2 alleviates high glucose-induced inhibition of osteoblast differentiation by modulating PI3K/AKT/GSK3β/β-catenin pathway.

Prolactin/androgen-inducible carboxypeptidase-D increases with nitrotyrosine and Ki67 for breast cancer progression in vivo, and upregulates progression markers VEGF-C and Runx2 in vitro

PURPOSE

Carboxypeptidase-D (CPD) cleaves C-terminal arginine (Arg) to produce nitric oxide (NO). Upregulation of CPD and NO by 17β-estradiol, prolactin (PRL), and androgen increases survival of human breast cancer (BCa) cells in vitro. To demonstrate similar events in vivo, CPD, nitrotyrosine (NT, hallmark of NO action), androgen receptor (AR), prolactin receptor (PRLR), and phospho-Stat5a (for activated PRLR) levels were evaluated in benign and malignant human breast tissues, and correlated with cell proliferation (Ki67) and BCa progression (Cullin-3) biomarkers.

METHODS

Paraffin-embedded breast tissues were analyzed by immunohistochemistry (IHC). BCa progression markers in human MCF-7 and T47D BCa cell lines treated with NO donor SIN-1 or PRL, ±CPD inhibitors were analyzed by RT-qPCR and immunoblotting.

RESULTS

IHC showed progressive increases in CPD, NT, Ki67, and Cullin-3 from low levels in benign tissues to high levels in ductal carcinoma in situ, low-grade, high-grade, and triple-negative BCa. CPD and NT staining were closely associated, implicating CPD in NO production. Phospho-Stat5a increased significantly from benign to high-grade BCa and was mostly nuclear. AR and PRLR were abundant in benign breast and BCa, including triple-negative tumors. SIN-1 and PRL increased VEGF-C and Runx2, but not Cullin-3, in BCa cell lines. PRL induction of VEGF-C and Runx2 was inhibited partly by CPD inhibitors, implicating NO, produced by PRL-regulated CPD, in BCa progression.

CONCLUSIONS

The CPD-Arg-NO pathway contributes to BCa progression in vitro and in vivo. PRL/androgen activation of the pathway support combined AR and PRLR blockade as an additional therapy for BCa.

Role of Runx2 in breast cancer-mediated bone metastasis

Breast cancer is one of the most prevalent forms of cancer in women. The currently available treatment for breast cancer is mostly curative except when it becomes metastatic. One of the major sites for metastasis of breast cancer is the bone. Homing of the circulating tumor cells is tightly regulated including a number of factors present in the cells and their microenvironment. Runx2, a transcription factor plays an important role in osteogenesis and breast cancer mediated bone metastases. One of the recent advances in molecular therapy includes the discovery of the small, non-coding microRNAs (miRNAs) and they target specific genes to reduce their expression at the post-transcriptional level. This review provides an outline of breast cancer mediated bone metastasis and summarizes the recent development on the regulation of Runx2 expression by miRNAs which can lead to novel molecular therapeutics for the same.

Involvement of Rictor/mTORC2 in cardiomyocyte differentiation of mouse embryonic stem cells in vitro

Rictor is a key regulatory/structural subunit of the mammalian target of rapamycin complex 2 (mTORC2) and is required for phosphorylation of Akt at serine 473. It plays an important role in cell survival, actin cytoskeleton organization and other processes in embryogenesis. However, the role of Rictor/mTORC2 in the embryonic cardiac differentiation has been uncovered. In the present study, we examined a possible link between Rictor expression and cardiomyocyte differentiation of the mouse embryonic stem (mES) cells. Knockdown of Rictor by shRNA significantly reduced the phosphorylation of Akt at serine 473 followed by a decrease in cardiomyocyte differentiation detected by beating embryoid bodies. The protein levels of brachyury (mesoderm protein), Nkx2.5 (cardiac progenitor cell protein) and α-Actinin (cardiomyocyte biomarker) decreased in Rictor knockdown group during cardiogenesis. Furthermore, knockdown of Rictor specifically inhibited the ventricular-like cells differentiation of mES cells with reduced level of ventricular-specific protein, MLC-2v. Meanwhile, patch-clamp analysis revealed that shRNA-Rictor significantly increased the number of cardiomyocytes with abnormal electrophysiology. In addition, the expressions and distribution patterns of cell-cell junction proteins (Cx43/Desmoplakin/N-cadherin) were also affected in shRNA-Rictor cardiomyocytes. Taken together, the results demonstrated that Rictor/mTORC2 might play an important role in the cardiomyocyte differentiation of mES cells. Knockdown of Rictor resulted in inhibiting ventricular-like myocytes differentiation and induced arrhythmias symptom, which was accompanied by interfering the expression and distribution patterns of cell-cell junction proteins. Rictor/mTORC2 might become a new target for regulating cardiomyocyte differentiation and a useful reference for application of the induced pluripotent stem cells.