Carcinoma-associated fibroblasts (CAFs) are abundant and heterogeneous stromal cells in tumor microenvironment that are critically involved in cancer progression. Here, we demonstrate that two cell-surface molecules, CD10 and GPR77, specifically define a CAF subset correlated with chemoresistance and poor survival in multiple cohorts of breast and lung cancer patients. CD10GPR77 CAFs promote tumor formation and chemoresistance by providing a survival niche for cancer stem cells (CSCs). Mechanistically, CD10GPR77 CAFs are driven by persistent NF-κB activation via p65 phosphorylation and acetylation, which is maintained by complement signaling via GPR77, a C5a receptor. Furthermore, CD10GPR77 CAFs promote successful engraftment of patient-derived xenografts (PDXs), and targeting these CAFs with a neutralizing anti-GPR77 antibody abolishes tumor formation and restores tumor chemosensitivity. Our study reveals a functional CAF subset that can be defined and isolated by specific cell-surface markers and suggests that targeting the CD10GPR77 CAF subset could be an effective therapeutic strategy against CSC-driven solid tumors.

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The mechanisms by which truncating mutations in MYBPC3 (encoding cardiac myosin-binding protein C; cMyBPC) or myosin missense mutations cause hypercontractility and poor relaxation in hypertrophic cardiomyopathy (HCM) are incompletely understood. Using genetic and biochemical approaches, we explored how depletion of cMyBPC altered sarcomere function. We demonstrated that stepwise loss of cMyBPC resulted in reciprocal augmentation of myosin contractility. Direct attenuation of myosin function, via a damaging missense variant (F764L) that causes dilated cardiomyopathy (DCM), normalized the increased contractility from cMyBPC depletion. Depletion of cMyBPC also altered dynamic myosin conformations during relaxation, enhancing the myosin state that enables ATP hydrolysis and thin filament interactions while reducing the super relaxed conformation associated with energy conservation. MYK-461, a pharmacologic inhibitor of myosin ATPase, rescued relaxation deficits and restored normal contractility in mouse and human cardiomyocytes with MYBPC3 mutations. These data define dosage-dependent effects of cMyBPC on myosin that occur across the cardiac cycle as the pathophysiologic mechanisms by which MYBPC3 truncations cause HCM. Therapeutic strategies to attenuate cMyBPC activity may rescue depressed cardiac contractility in patients with DCM, whereas inhibiting myosin by MYK-461 should benefit the substantial proportion of patients with HCM with MYBPC3 mutations.

Purpose: Aspirin has recently been reported to reduce both the incidence and the risk of metastasis in colon cancer. However, there is no evidence at the cellular levels or in the animal models for such an effect of aspirin on cancer metastasis.Experimental Design: MTT assay, colony formation assay, and apoptosis assay were employed to analyze the effects of aspirin on the osteosarcoma cell viability in vitro. The NF-kB activity was measured by the NF-kB p65 luciferase reporter. Western blotting was used to analyze the proteins in cells. The migration and invasion abilities of osteosarcoma cells in vitro were measured by the Transwell assay. Xenograft-bearing mice were used to assess the roles of aspirin in both tumor growth and metastasis of osteosarcoma in vivo (n ¼ 5-8 mice/group). An unpaired Student t test or ANOVA with the Bonferroni post hoc test were used for the statistical comparisons.Results: Aspirin reduced cell viability in a dose-and timedependent manner in osteosarcoma cell lines, and aspirin synergistically sensitized osteosarcoma cells to cisplatin (DDP) in vitro and in vivo (P < 0.001). Moreover, aspirin markedly repressed the migration and invasion of osteosarcoma cells in vitro (P < 0.001), and dramatically diminished the occurrence of osteosarcoma xenograft metastases to the lungs in vivo (P < 0.001). Mechanistically, aspirin diminishes osteosarcoma migration, invasion, and metastasis through the NF-kB pathway.Conclusions: Aspirin suppresses both the growth and metastasis of osteosarcoma through the NF-kB pathway at the cellular level and in the animal models.

Polycomb chromobox (CBX) proteins participate in the polycomb repressive complex (PRC1) that mediates epigenetic gene silencing and endows PRC1 with distinct oncogenic or tumor suppressor functions in a cell-type-dependent manner. In this study, we report that inhibition of cell migration, invasion, and metastasis in colorectal carcinoma requires CBX4-mediated repression of Runx2, a key transcription factor that promotes colorectal carcinoma metastasis. CBX4 inversely correlated with Runx2 expression in colorectal carcinoma tissues, and the combination of high CBX4 expression and low Runx2 expression significantly correlated with overall survival, more so than either CBX4 or Runx2 expression alone. Mechanistically, CBX4 maintained recruited histone deacetylase 3 (HDAC3) to the Runx2 promoter, which maintained a deacetylated histone H3K27 state to suppress Runx2 expression. This function of CBX4 was dependent on its interaction with HDAC3, but not on its SUMO E3 ligase, its chromodomain, or the PRC1 complex. Disrupting the CBX4-HDAC3 interaction abolished Runx2 inhibition as well as the inhibition of cell migration and invasion. Collectively, our data show that CBX4 may act as a tumor suppressor in colorectal carcinoma, and strategies that stabilize the interaction of CBX4 with HDAC3 may benefit the colorectal carcinoma patients with metastases. Cancer Res; 76(24); 7277-89. ©2016 AACR.

Osteosarcoma, an aggressive malignant cancer, has a high lung metastasis rate and lacks therapeutic target. Here, we reported that chromobox homolog 4 (CBX4) was overexpressed in osteosarcoma cell lines and tissues. CBX4 promoted metastasis by transcriptionally upregulating Runx2 via the recruitment of GCN5 to the Runx2 promoter. The phosphorylation of CBX4 at T437 by casein kinase 1α (CK1α) facilitated its ubiquitination at both K178 and K280 and subsequent degradation by CHIP, and this phosphorylation of CBX4 could be reduced by TNFα. Consistently, CK1α suppressed cell migration and invasion through inhibition of CBX4. There was a reverse correlation between CK1α and CBX4 in osteosarcoma tissues, and CK1α was a valuable marker to predict clinical outcomes in osteosarcoma patients with metastasis. Pyrvinium pamoate (PP) as a selective activator of CK1α could inhibit osteosarcoma metastasis via the CK1α/CBX4 axis. Our findings indicate that targeting the CK1α/CBX4 axis may benefit osteosarcoma patients with metastasis.

The effect of polycomb chromobox (Cbx) proteins in cancer is context-dependent. The Chromobox homolog 8 (CBX8) was originally characterized as a transcriptional repressor, which inhibits cell proliferation in Ink4a-Arf-dependent and -independent manner. However, the role of CBX8 in colorectal cancer remains unknown. Here, we found that high CBX8 expression was associated with a low rate of distant metastasis and good prognosis in CRC patients, even though CBX8 was up-regulated in CRC cell lines and clinical samples. Knockdown of CBX8 inhibited CRC proliferation in vitro and in vivo, mostly by increasing p53 and its downstream effectors. However, knockdown of CBX8 enhanced CRC migration, invasion and metastasis in vitro and in vivo, in part through direct up-regulation of integrin β4 (ITGB4) that in turn decreased RhoA activity. Collectively, the knockdown of CBX8 inhibited CRC proliferation, while promoting its metastasis, thus exerting paradoxical effects in CRC progression.

The cytoplasmic CBX4 protein may be a useful prognostic biomarker and a potential therapeutic target for HCC.