CRACD loss induces neuroendocrine cell plasticity of lung adenocarcinoma.

Tumor cell plasticity contributes to intratumoral heterogeneity and therapy resistance. Through cell plasticity, some lung adenocarcinoma (LUAD) cells transform into neuroendocrine (NE) tumor cells. However, the mechanisms of NE cell plasticity remain unclear. CRACD (capping protein inhibiting regulator of actin dynamics), a capping protein inhibitor, is frequently inactivated in cancers. CRACD knockout (KO) is sufficient to de-repress NE-related gene expression in the pulmonary epithelium and LUAD cells. In LUAD mouse models, Cracd KO increases intratumoral heterogeneity with NE gene expression. Single-cell transcriptomic analysis showed that Cracd KO-induced NE cell plasticity is associated with cell de-differentiation and stemness-related pathway activation. The single-cell transcriptomic analysis of LUAD patient tumors recapitulates that the distinct LUAD NE cell cluster expressing NE genes is co-enriched with impaired actin remodeling. This study reveals the crucial role of CRACD in restricting NE cell plasticity that induces cell de-differentiation of LUAD.

Tumor niche network-defined subtypes predict immunotherapy response of esophageal squamous cell cancer.

Despite the promising outcomes of immune checkpoint inhibitors (ICIs), resistance to ICI presents a new challenge. Therefore, selecting patients for specific ICI applications is crucial for maximizing therapeutic efficacy. Herein, we curated 69 human esophageal squamous cell cancer (ESCC) patients' tumor microenvironment (TME) single-cell transcriptomic datasets to subtype ESCC. Integrative analyses of the cellular network and transcriptional signatures of T cells and myeloid cells define distinct ESCC subtypes characterized by T cell exhaustion, and interleukin (IL) and interferon (IFN) signaling. Furthermore, this approach classifies ESCC patients into ICI responders and non-responders, as validated by whole tumor transcriptomes and liquid biopsy-based single-cell transcriptomes of anti-PD-1 ICI responders and non-responders. Our study stratifies ESCC patients based on TME transcriptional network, providing novel insights into tumor niche remodeling and potentially predicting ICI responses in ESCC patients.

E-cadherin loss drives diffuse-type gastric tumorigenesis via EZH2-mediated reprogramming.

Diffuse-type gastric adenocarcinoma (DGAC) is a deadly cancer often diagnosed late and resistant to treatment. While hereditary DGAC is linked to CDH1 mutations, the role of CDH1/E-cadherin inactivation in sporadic DGAC tumorigenesis remains elusive. We discovered CDH1 inactivation in a subset of DGAC patient tumors. Analyzing single-cell transcriptomes in malignant ascites, we identified two DGAC subtypes: DGAC1 (CDH1 loss) and DGAC2 (lacking immune response). DGAC1 displayed distinct molecular signatures, activated DGAC-related pathways, and an abundance of exhausted T cells in ascites. Genetically engineered murine gastric organoids showed that Cdh1 knock-out (KO), KrasG12D, Trp53 KO (EKP) accelerates tumorigenesis with immune evasion compared with KrasG12D, Trp53 KO (KP). We also identified EZH2 as a key mediator promoting CDH1 loss-associated DGAC tumorigenesis. These findings highlight DGAC's molecular diversity and potential for personalized treatment in CDH1-inactivated patients.

Key Genetic Determinants Driving Esophageal Squamous Cell Carcinoma Initiation and Immune Evasion.

BACKGROUND & AIMS: Despite recent progress in identifying aberrant genetic and epigenetic alterations in esophageal squamous cell carcinoma (ESCC), the mechanism of ESCC initiation remains unknown. METHODS: Using CRISPR/Cas 9-based genetic ablation, we targeted 9 genes (TP53, CDKN2A, NOTCH1, NOTCH3, KMT2D, KMT2C, FAT1, FAT4, and AJUBA) in murine esophageal organoids. Transcriptomic phenotypes of organoids and chemokine released by organoids were analyzed by single-cell RNA sequencing. Tumorigenicity and immune evasion of organoids were monitored by allograft transplantation. Human ESCC single-cell RNA sequencing data sets were analyzed to classify patients and find subsets relevant to organoid models and immune evasion. RESULTS: We established 32 genetically engineered esophageal organoids and identified key genetic determinants that drive ESCC initiation. A single-cell transcriptomic analysis uncovered that Trp53, Cdkn2a, and Notch1 (PCN) triple-knockout induces neoplastic features of ESCC by generating cell lineage heterogeneity and high cell plasticity. PCN knockout also generates an immunosuppressive niche enriched with exhausted T cells and M2 macrophages via the CCL2-CCR2 axis. Mechanistically, CDKN2A inactivation transactivates CCL2 via nuclear factor-κB. Moreover, comparative single-cell transcriptomic analyses stratified patients with ESCC and identified a specific subtype recapitulating the PCN-type ESCC signatures, including the high expression of CCL2 and CD274/PD-L1. CONCLUSIONS: Our study unveils that loss of TP53, CDKN2A, and NOTCH1 induces esophageal neoplasia and immune evasion for ESCC initiation and proposes the CCL2 blockade as a viable option for targeting PCN-type ESCC.

CRACD suppresses neuroendocrinal plasticity of lung adenocarcinoma.

Tumor cell plasticity contributes to intratumoral heterogeneity and therapy resistance. Through cell plasticity, lung adenocarcinoma (LUAD) cells transform into neuroendocrinal (NE) tumor cells. However, the mechanisms of NE cell plasticity remain unclear. CRACD, a capping protein inhibitor, is frequently inactivated in cancers. CRACD knock-out (KO) de-represses NE-related gene expression in the pulmonary epithelium and LUAD cells. In LUAD mouse models, Cracd KO increases intratumoral heterogeneity with NE gene expression. Single-cell transcriptomic analysis showed that Cracd KO-induced NE plasticity is associated with cell de-differentiation and activated stemness-related pathways. The single-cell transcriptomes of LUAD patient tumors recapitulate that the distinct LUAD NE cell cluster expressing NE genes is co-enriched with SOX2, OCT4, and NANOG pathway activation, and impaired actin remodeling. This study reveals an unexpected role of CRACD in restricting NE cell plasticity that induces cell de-differentiation, providing new insights into cell plasticity of LUAD.

CDH1 loss promotes diffuse-type gastric cancer tumorigenesis via epigenetic reprogramming and immune evasion.

Diffuse-type gastric adenocarcinoma (DGAC) is a deadly cancer often diagnosed late and resistant to treatment. While hereditary DGAC is linked to CDH1 gene mutations, causing E-Cadherin loss, its role in sporadic DGAC is unclear. We discovered CDH1 inactivation in a subset of DGAC patient tumors. Analyzing single-cell transcriptomes in malignant ascites, we identified two DGAC subtypes: DGAC1 (CDH1 loss) and DGAC2 (lacking immune response). DGAC1 displayed distinct molecular signatures, activated DGAC-related pathways, and an abundance of exhausted T cells in ascites. Genetically engineered murine gastric organoids showed that Cdh1 knock-out (KO), KrasG12D, Trp53 KO (EKP) accelerates tumorigenesis with immune evasion compared to KrasG12D, Trp53 KO (KP). We also identified EZH2 as a key mediator promoting CDH1 loss-associated DGAC tumorigenesis. These findings highlight DGAC's molecular diversity and potential for personalized treatment in CDH1-inactivated patients.

Tumor Niche Network-Defined Subtypes Predict Immunotherapy Response of Esophageal Squamous Cell Cancer.

Despite the promising outcomes of immune checkpoint blockade (ICB), resistance to ICB presents a new challenge. Therefore, selecting patients for specific ICB applications is crucial for maximizing therapeutic efficacy. Herein we curated 69 human esophageal squamous cell cancer (ESCC) patients' tumor microenvironment (TME) single-cell transcriptomic datasets to subtype ESCC. Integrative analyses of the cellular network transcriptional signatures of T cells, myeloid cells, and fibroblasts define distinct ESCC subtypes characterized by T cell exhaustion, Interferon (IFN) a/b signaling, TIGIT enrichment, and specific marker genes. Furthermore, this approach classifies ESCC patients into ICB responders and non-responders, as validated by liquid biopsy single-cell transcriptomics. Our study stratifies ESCC patients based on TME transcriptional network, providing novel insights into tumor niche remodeling and predicting ICB responses in ESCC patients.

CRACD loss promotes small cell lung cancer tumorigenesis via EZH2-mediated immune evasion.

The mechanisms underlying immune evasion and immunotherapy resistance in small cell lung cancer (SCLC) remain unclear. Herein, we investigate the role of CRACD tumor suppressor in SCLC. We found that CRACD is frequently inactivated in SCLC, and Cracd knockout (KO) significantly accelerates SCLC development driven by loss of Rb1, Trp53, and Rbl2. Notably, the Cracd-deficient SCLC tumors display CD8+ T cell depletion and suppression of antigen presentation pathway. Mechanistically, CRACD loss silences the MHC-I pathway through EZH2. EZH2 blockade is sufficient to restore the MHC-I pathway and inhibit CRACD loss-associated SCLC tumorigenesis. Unsupervised single-cell transcriptomic analysis identifies SCLC patient tumors with concomitant inactivation of CRACD, impairment of tumor antigen presentation, and downregulation of EZH2 target genes. Our findings define CRACD loss as a new molecular signature associated with immune evasion of SCLC cells and proposed EZH2 blockade as a viable option for CRACD-negative SCLC treatment.

WNT5A-RHOA Signaling Is a Driver of Tumorigenesis and Represents a Therapeutically Actionable Vulnerability in Small Cell Lung Cancer.

WNT signaling represents an attractive target for cancer therapy due to its widespread oncogenic role. However, the molecular players involved in WNT signaling and the impact of their perturbation remain unknown for numerous recalcitrant cancers. Here, we characterize WNT pathway activity in small cell lung cancer (SCLC) and determine the functional role of WNT signaling using genetically engineered mouse models. ß-Catenin, a master mediator of canonical WNT signaling, was dispensable for SCLC development, and its transcriptional program was largely silenced during tumor development. Conversely, WNT5A, a ligand for ß-catenin-independent noncanonical WNT pathways, promoted neoplastic transformation and SCLC cell proliferation, whereas WNT5A deficiency inhibited SCLC development. Loss of p130 in SCLC cells induced expression of WNT5A, which selectively increased Rhoa transcription and activated RHOA protein to drive SCLC. Rhoa knockout suppressed SCLC development in vivo, and chemical perturbation of RHOA selectively inhibited SCLC cell proliferation. These findings suggest a novel requirement for the WNT5A-RHOA axis in SCLC, providing critical insights for the development of novel therapeutic strategies for this recalcitrant cancer. This study also sheds light on the heterogeneity of WNT signaling in cancer and the molecular determinants of its cell-type specificity. SIGNIFICANCE: The p130-WNT5A-RHOA pathway drives SCLC progression and is a potential target for the development of therapeutic interventions and biomarkers to improve patient treatment.

Shift of switching threshold in low-dimensional semiconductor-based complementary inverters via inkjet printing.

MoS2crystals grown by chemical vapor deposition are suited for realization of practical 2D semiconductor-based electronics. In order to construct complementary circuits with n-type MoS2, another p-type semiconductor, whose performance can be adjusted corresponding to that of MoS2in the limited chip area, has to be sought. Herein, we present a method for tuning switching threshold voltages of complementary inverters simply via inkjet printing without changing their channel dimensions. Random networks of inkjet printed single-walled carbon nanotubes are formed as p-channels beside MoS2, and their density and thickness are controlled by varying the number of printed layers. As a result, p-type transistor characteristics as well as inverter characteristics are facilely tuned only by varying the number of printed layers.

A new murine esophageal organoid culture method and organoid-based model of esophageal squamous cell neoplasia.

Organoids mimic the physiologic and pathologic events of organs. However, no consensus on esophageal organoid (EO) culture methods has been reached. Moreover, organoid models reproducing esophageal squamous cell carcinoma (ESCC) initiation have been unavailable. Herein, we sought to develop an esophageal minimum essential organoid culture medium (E-MEOM) for culturing murine EOs and establishing an early ESCC model. We formulated E-MEOM to grow EOs from a single cell with clonal expansion, maintenance, and passage. We found that EOs cultured in E-MEOM were equivalent to the esophageal epithelium by histological analysis and transcriptomic study. Trp53 knockout and Kras G12D expression in EOs induced the development of esophageal squamous neoplasia, an early lesion of ESCC. Here we propose the new formula for EO culture with minimum components and the organoid model recapitulating ESCC initiation, laying the foundation for ESCC research and drug discovery.

Dual-Mode Radar Sensor for Indoor Environment Mapping.

In this paper, we introduce mapping results in an indoor environment based on our own developed dual-mode radar sensor. Our radar system uses a frequency-modulated continuous wave (FMCW) with a center frequency of 62 GHz and a multiple-input multiple-output antenna system. In addition, the FMCW radar sensor we designed is capable of dual-mode detection, which alternately transmits two waveforms using different bandwidths within one frame. The first waveform is for long-range detection, and the second waveform is for short-range detection. This radar system is mounted on a small robot that moves in indoor environments such as rooms or hallways, and the radar and the robot send and receive necessary information to each other. The radar estimates the distance, velocity, and angle information of targets around the radar-equipped robot. Then, the radar receives information about the robot's motion from the robot, such as its speed and rotation angle. Finally, by combining the motion information and the detection results, the radar-equipped robot maps the indoor environment while finding its own position. Compared to the actual map data, the radar-based mapping is effectively achieved through the radar system we developed.

The role of S100A4 for bone metastasis in prostate cancer cells.

BACKGROUND: Prostate cancers frequently metastasize to bone, where the best microenvironment for distant colonization is provided. Since osteotropic metastasis of prostate cancer is a critical determinant of patients' survival, searches for preventive measures are ongoing in the field. Therefore, it is important to dissect the mechanisms of each step of bone metastasis, including the epithelial-mesenchymal transition (EMT) and cross-talk between metastatic niches and cancer cells. METHODS: In this study, we established a highly bone-metastatic subline of human prostate cancer cells by selecting bone-homing population of PC3 cells after cardiac injection of eight-week-old male BALB/c-nude mice. Then we assessed the proliferation, EMT characteristics, and migration properties of the subline (mtPC3) cells in comparison with the parental PC3 cells. To investigate the role of S100A4, we performed gene knock-down by lentiviral transduction, or treated cells with recombinant S100A4 protein or a S100A4-neutralizing antibody. The effect of cancer cells on osteoclastogenesis was evaluated after treatment of pre-osteoclasts with conditioned medium (CM) from cancer cells. RESULTS: The mtPC3 cells secreted a markedly high level of S100A4 protein and showed elevated cell proliferation and mesenchymal properties. The increased proliferation and EMT traits of mtPC3 cells was inhibited by S100A4 knock-down, but was not affected by exogenous S100A4. Furthermore, S100A4 released from mtPC3 cells stimulated osteoclast development via the cell surface receptor RAGE. Down-regulation or neutralization of S100A4 in the CM of mtPC3 cells attenuated cancer-induced osteoclastogenesis. CONCLUSION: Altogether, our results suggest that intracellular S100A4 promotes cell proliferation and EMT characteristics in tumor cells, and that secreted S100A4 activates osteoclastogenesis, contributing to osteolytic bone metastasis. Thus, S100A4 upregulation in cancer cells highly metastatic to bone might be a key element in regulating bone metastasis.

Reversible 100 mA Current Switching in a VO2/Al2O3-Based Two-Terminal Device Using Focused Far-Infrared Laser Pulses.

In this study, we implemented reversible current switching (RCS) of 100 mA in a two-terminal device based on a vanadium dioxide (VO2) thin film, which could be controlled by far-infrared (FIR) laser pulses. The VO2 thin films used for fabrication of two-terminal devices were grown on sapphire (Al2O3) substrates using a pulsed laser deposition method. An optimal deposition condition was determined by analyzing the resistance-temperature curves of deposited VO2 thin films and the current-voltage characteristics of two-terminal devices based on these films, which were suggested in our previous works. The film surface of the VO2-based device was directly irradiated using focused CO2 laser pulses, and the insulator-metal transition or metal-insulator transition of the VO2 thin film could be triggered depending on laser irradiation. Consequently, RCS of up to 100 mA could be accomplished. This on-state current is close to the upper limit of the current flowing through our VO2 device. The switching contrast, defined as the ratio between on-state and off-state currents, was evaluated and found to be ˜11,962. The average rising and falling times of the switched current were found to be ˜29.2 and ˜71.7 ms, respectively. In comparison with our previous work, the improved heat dissipation structure and the high-quality thin film could maintain the switching contrast at a similar level, although the on-state current was increased by about two times.

The dynactin subunit DCTN1 controls osteoclastogenesis via the Cdc42/PAK2 pathway.

Osteoclasts (OCs), cells specialized for bone resorption, are generated from monocyte/macrophage precursors by a differentiation process governed by RANKL. Here, we show that DCTN1, a key component of the dynactin complex, plays important roles in OC differentiation. The expression of DCTN1 was upregulated by RANKL. The inhibition of DCTN1 expression by gene knockdown suppressed OC formation, bone resorption, and the induction of NFATc1 and c-Fos, critical transcription factors for osteoclastogenesis. More importantly, the activation of Cdc42 by RANKL was inhibited upon DCTN1 silencing. The forced expression of constitutively active Cdc42 restored the OC differentiation of precursors with DCTN1 deletion. In addition, PAK2 was found to be activated by RANKL and to function downstream of Cdc42. The DCTN1-Cdc42 axis also inhibited apoptosis and caspase-3 activation. Furthermore, the anti-osteoclastogenic effect of DCTN1 knockdown was verified in an animal model of bone erosion. Intriguingly, DCTN1 overexpression was also detrimental to OC differentiation, suggesting that DCTN1 should be regulated at the appropriate level for effective osteoclastogenesis. Collectively, our results reveal that DCTN1 participates in the activation of Cdc42/PAK2 signaling and the inhibition of apoptosis during osteoclastogenesis.

Effects of High-Intensity Interval Training Versus Moderate-Intensity Continuous Training on Epicardial Fat Thickness and Endothelial Function in Hypertensive Metabolic Syndrome.

Background: Hypertension is common in patients with metabolic syndrome (MS), and it is an important risk factor for cardiovascular-related morbidity and mortality. Compared to moderate-intensity continuous training (MICT), high-intensity interval training (HIIT) is considered a time-efficient exercise strategy for cardiometabolic health. We compared the effects of HIIT and MICT on epicardial fat thickness (EFT) and endothelial function in patients with hypertensive MS. Methods: In total, 34 participants with hypertensive MS (mean age: 50.9 ± 7.9 years) were randomized to either the HIIT (n = 17) or MICT (n = 17) group. In the HIIT group, participants performed for 3 min at 40% heart-rate reserve (HRR), which was alternated with 3 min at 80% HRR, whereas participants in the MICT group performed at 60% of HRR thrice a week for 8 weeks. EFT was measured with echocardiography, and endothelial function was determined by quantifying endothelial progenitor cells (EPCs), nitric oxide (NO), and flow-mediated dilation (FMD). Results: After exercise training, patients in both the groups showed significantly decreased EFT (P < 0.001 and P < 0.01) and improved FMD (P < 0.001 and P < 0.01). NO (P < 0.05) and EPCs (CD34/KDR, P < 0.01; CD34/CD117, P < 0.05; CD34/CD133, P < 0.05) were significantly improved in the HIIT group, but not in the MICT group. In addition, HIIT had a greater effect than MICT on FMD (group difference, P < 0.05) and EFT (group difference, P < 0.05). Conclusions: Compared to MICT, HIIT seems to better improve FMD and EFT. This finding suggests that HIIT could be more effective than MICT in improving endothelial function in patients with hypertensive MS.

A CTGF-RUNX2-RANKL Axis in Breast and Prostate Cancer Cells Promotes Tumor Progression in Bone.

Metastasis to bone is a frequent occurrence in patients with breast and prostate cancers and inevitably threatens the patient's quality of life and survival. Identification of cancer-derived mediators of bone metastasis and osteolysis may lead to novel therapeutic strategies. In this study, we established highly bone-metastatic PC3 prostate and MDA-MB-231 (MDA) breast cancer cell sublines by in vivo selection in mice. In bone-metastatic cancer cells, the expression and secretion of connective tissue growth factor (CTGF) were highly upregulated. CTGF knockdown in bone-metastatic cells decreased invasion activity and MMP expression. RUNX2 overexpression in the CTGF knockdown cells restored the invasion activity and MMP expression. In addition, CTGF increased RUNX2 protein stability by inducing its acetylation via p300 acetyl transferase. The integrin αvß3 receptor mediated these effects of CTGF. Furthermore, CTGF promoted RUNX2 recruitment to the RANKL promoter, resulting in increased RANKL production from the tumor cells and subsequent stimulation of osteoclastogenesis from precursor cells. In addition, animal model with injection of CTGF knocked-down prostate cancer cells into 6-week old BALB/c male mice showed reduced osteolytic lesions. More importantly, the expression levels of CTGF and RANKL showed a strong positive correlation in human primary breast tumor tissues and were higher in bone metastases than in other site metastases. These findings indicate that CTGF plays crucial roles for osteolytic bone metastasis both by enhancing invasiveness of tumor cells and by producing RANKL for osteoclastogenesis. Targeting CTGF may lead to the development of effective preventive and therapeutic strategies for osteolytic metastasis. © 2019 American Society for Bone and Mineral Research.

Bidirectional Current Triggering in VO2-Based Device with High-Repetition-Rate Pulse Beams Using Near-Infrared Laser Diode.

Here we report bidirectional current triggering (BCT) with a high repetition rate, achieved in a twoterminal planar device based on a vanadium dioxide (VO2) thin film by using a laser diode with a center wavelength of 976 nm as an excitation source. The VO2 thin film was grown on a sapphire (Al2O3) substrate using a pulsed laser deposition method, and the two-terminal planar device was fabricated by sawing the grown film into microscale unit devices, each of which was then attached onto a printed circuit board. Current triggering was performed by controlling the output power of the laser beam incident on the device surface. The proposed device allows stable current triggering operation even with laser pulses of higher repetition rate and lower energy because it is designed to have low heat capacity and thermal conductivity. Experimental results showed that a BCT of up to 30 mA was achieved at the maximum repetition rate of 8.0 Hz. The switching contrast between off- and on-state currents was calculated to be ~7295, and average rising and falling times of the current triggering were measured to be ~18.3 and ~22.5 ms, respectively.

Bidirectional Current Gating in Two-Terminal VO2/AIN/Si Heterostructure Device Using 976 nm Laser Diode.

Bidirectional current gating was realized in a vanadium dioxide (VO2) thin film-based two-terminal heterostructure device using a near-infrared laser diode (LD) with a center wavelength of 976 nm. The VO2 thin film used in the device fabrication was grown through pulsed laser deposition on a Si substrate with an aluminum nitride (AIN) buffer layer. The phase transition temperature of the fabricated VO2/AIN/Si heterostructure device was ~78 °C, which is higher by ~10 °C than that of the device based on a conventional VO2 thin film grown on a sapphire (Al2O3) substrate. Bidirectional current gating up to 60 mA was realized by directly irradiating the exposed thin film surface with the focused laser beam. The transient responses of the current flowing through the device were investigated for various pulse widths and repetition rates of the focused laser beam. The average switching contrast between off- and on-states was measured as ~9993. The average rise time of the current gating was ~31.5 ms with a much shorter fall time of ~4.0 ms. Our VO2/AIN/Si heterostructure device could provide a high on-state current and fast response due to a smaller device dimension and higher phase transition temperature compared with previous implementations.

Salt-inducible kinase 1 regulates bone anabolism via the CRTC1-CREB-Id1 axis.

New bone anabolic agents for the effective treatment of bone metabolic diseases like osteoporosis are of high clinical demand. In the present study, we reveal the function of salt-inducible kinase 1 (SIK1) in regulating osteoblast differentiation. Gene knockdown of SIK1 but not of SIK2 or SIK3 expression in primary preosteoblasts increased osteoblast differentiation and bone matrix mineralization. SIK1 also regulated the proliferation of osteoblastic precursor cells in osteogenesis. This negative control of osteoblasts required the catalytic activity of SIK1. SIK1 phosphorylated CREB regulated transcription coactivator 1 (CRTC1), preventing CRTC1 from enhancing CREB transcriptional activity for the expression of osteogenic genes like Id1. Furthermore, SIK1 knockout (KO) mice had higher bone mass, osteoblast number, and bone formation rate versus littermate wild-type (WT) mice. Preosteoblasts from SIK1 KO mice showed more osteoblastogenic potential than did WT cells, whereas osteoclast generation among KO and WT precursors was indifferent. In addition, bone morphogenic protein 2 (BMP2) suppressed both SIK1 expression as well as SIK1 activity by protein kinase A (PKA)-dependent mechanisms to stimulate osteogenesis. Taken together, our results indicate that SIK1 is a key negative regulator of preosteoblast proliferation and osteoblast differentiation and that the repression of SIK1 is crucial for BMP2 signaling for osteogenesis. Therefore, we propose SIK1 to be a useful therapeutic target for the development of bone anabolic strategies.