Acetylation-dependent function of human single-stranded DNA binding protein 1.

Human single-stranded DNA binding protein 1 (hSSB1) plays a critical role in responding to DNA damage and maintaining genome stability. However, the regulation of hSSB1 remains poorly studied. Here, we determined that hSSB1 acetylation at K94 mediated by the acetyltransferase p300 and the deacetylases SIRT4 and HDAC10 impaired its ubiquitin-mediated degradation by proteasomes. Moreover, we demonstrated that the hSSB1-K94R mutant had reduced cell survival in response to DNA damage by radiation or chemotherapy drugs. Furthermore, the p300/CBP inhibitor C646 significantly enhanced the sensitivity of cancer cells to chemotherapy drugs, and a positive correlation between hSSB1 and p300 level was observed in clinical colorectal cancer samples. Acetylation, a novel regulatory modification of hSSB1, is crucial for its function under both physiological and pathological conditions. This finding supports the notion that the combination of chemotherapy drugs with acetylation inhibitors may benefit cancer patients.

Iodide etching for one-step quantitative assay of the number of DNA molecules capped on gold nanoparticles.

Developing a direct method to easily quantify the number of DNA capped on gold nanoparticles (GNPs) is of great significance. Herein, we found that the high concentration of iodine ion (I-) can not only replace the ligands on the surface of GNPs but can also completely etch the particles by virtue of its strong reducibility. According to this finding, a mild, cost-effective, environment-friendly, and non-toxic strategy was constructed to directly and accurately estimate the amount of DNA coupled on GNPs. Due to nanometal surface energy transfer (NSET) that happened between the DNA-FAM donor and the GNPs receptor, the fluorescence was quenched; after incubating with the etching reagent 6 M I-, the recuperative fluorescence was detected directly. This method can easily estimate the number of DNA attached on the GNPs surface by one step. In a nutshell, it is a smart strategy to apply iodide etching for DNA quantification on the surface of GNPs, which breaks through the drawbacks of traditional DNA quantification strategies such as pollution, being expensive and even dangerous. This strategy takes a solid step forward for the refinement and optimization of DNA quantification and can also be more effective in detecting the number of other molecules capped on the GNPs surface, indicating that the iodide etching method is greatly helpful in bio-detection assays and nanoparticle-based therapeutics.

Highly stable surface-enhanced Raman spectroscopy assay on abnormal thrombin levels in the blood plasma of cancer patients.

The accurate discrimination of specific protein levels in the blood of cancer patients is of great importance in clinical diagnostics and prognosis. Here, we report a double-aptamer sandwich strategy on plasmonic magnetic beads (MBs) for a dual-reporter surface-enhanced Raman spectroscopy (SERS) assay for assessing abnormal thrombin (TB) levels in the blood plasma of cancer patients. This SERS assay demonstrated a linear analysis range of 20-400 pM in serum with a limit of detection as low as 20 pM, and to the best of our knowledge, this represents the first attempt to highly stably discriminate an abnormal TB level in the plasma of clinical cancer patients. Two recognition elements of TB aptamers provided high specificity and the dual-reporter assay demonstrated greatly reduced false-positive signals. The sandwich complex produced an efficient SERS "hot spot" to make up for the flaws of the insufficient enhancement of monomer metal nanoparticles. The plasmonic MBs enabled the direct tracking of ultratrace proteins in plasma while avoiding complicated pretreatment with only a few washing steps required. As a preliminary exploration, our report details a new potential tool with high sensitivity, selectivity, and practicality for disease-related protein testing in clinical diagnostics and prognosis.

Low expression of centrosomal protein 78 (CEP78) is associated with poor prognosis of colorectal cancer patients.

BACKGROUND: Centrosomal protein 78 (CEP78) has been characterized as a component of the centrosome required for the regulation of centrosome-related events during the cell cycle, but its role in human cancers remains unclear. This study aimed to investigate the role and the clinical value of CEP78 in colorectal cancer (CRC). METHODS: Quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry were performed to examine CEP78 expression in CRC tissues and adjacent noncancerous tissues. The association between CEP78 expression and clinical outcomes of CRC patients was determined. The effect of CEP78 on cell growth was examined in vitro by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, colony formation, and flow cytometry assays and in vivo using a nude mouse model. RESULTS: The expression level of CEP78 was significantly lower in tumor tissues than in the adjacent normal tissues (P < 0.01). Low CEP78 expression was significantly associated with poor differentiation (P = 0.003), large tumor size (P = 0.017), lymphatic metastasis (P = 0.034), distant metastasis (P = 0.029), and advanced stage (P = 0.011). Kaplan-Meier analysis indicated that patients with low CEP78 expression had shorter survival than those with high CEP78 expression (P < 0.01). Overexpression of CEP78 in CRC cells significantly reduced cell viability and colony formation in vitro and halted tumor growth in vivo. Further study showed that CEP78 reintroduction in CRC cells resulted in G2/M phase arrest rather than cell apoptosis. CONCLUSIONS: CEP78 might function as a tumor suppressor and serve as a novel prognostic marker in CRC.

KCTD12 Regulates Colorectal Cancer Cell Stemness through the ERK Pathway.

Targeting cancer stem cells (CSCs) in colorectal cancer (CRC) remains a difficult problem, as the regulation of CSCs in CRC is poorly understood. Here we demonstrated that KCTD12, potassium channel tetramerization domain containing 12, is down-regulated in the CSC-like cells of CRC. The silencing of endogenous KCTD12 and the overexpression of ectopic KCTD12 dramatically enhances and represses CRC cell stemness, respectively, as assessed in vitro and in vivo using a colony formation assay, a spheroid formation assay and a xenograft tumor model. Mechanistically, KCTD12 suppresses CRC cell stemness markers, such as CD44, CD133 and CD29, by inhibiting the ERK pathway, as the ERK1/2 inhibitor U0126 abolishes the increase in expression of CRC cell stemness markers induced by the down-regulation of KCTD12. Indeed, a decreased level of KCTD12 is detected in CRC tissues compared with their adjacent normal tissues and is an independent prognostic factor for poor overall and disease free survival in patients with CRC (p = 0.007). Taken together, this report reveals that KCTD12 is a novel regulator of CRC cell stemness and may serve as a novel prognostic marker and therapeutic target for patients with CRC.

Aspirin Suppresses the Growth and Metastasis of Osteosarcoma through the NF-κB Pathway.

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-κB activity was measured by the NF-κB 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 = 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 time-dependent 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-κB pathway. CONCLUSIONS: Aspirin suppresses both the growth and metastasis of osteosarcoma through the NF-κB pathway at the cellular level and in the animal models.

Targeting the anaphase-promoting complex/cyclosome (APC/C)- bromodomain containing 7 (BRD7) pathway for human osteosarcoma.

Osteosarcoma is the most common primary malignant bone tumor in childhood and adolescence and has a propensity for local invasion and early lung metastasis. However, the current therapies often result in chemoresistance, and a therapeutic target is not available in the clinic for osteosarcoma. Here, we report that BRD7 forms a complex with the anaphase-promoting complex/cyclosome (APC/C) and is degraded by APC/C(cdh1) and APC/C(cdc20) during the cell cycle. Moreover, BRD7 is a tumor suppressor in osteosarcoma, and the BRD7 mutant resistant to degradation by APC/C is more efficient than the wild-type protein at suppressing proliferation, colony formation, and tumor growth of osteosarcoma in vitro and in vivo. The combination of proTAME, an inhibitor of APC/C, with chemotherapeutic drugs efficiently targets osteosarcoma in vitro. Furthermore, there is a strong inverse correlation of protein levels between BRD7 and Cdh1 or Cdc20, and lower BRD7 expression is an indicator for poor prognosis in patients with osteosarcoma. Collectively, our results indicate that targeting the APC/C-BRD7 pathway may be a novel strategy for treating osteosarcoma.