MKRN1 promotes colorectal cancer metastasis by activating the TGF-ß signalling pathway through SNIP1 protein degradation.

BACKGROUND: The Makorin ring finger protein 1 (MKRN1) gene, also called RNF61, is located on the long arm of chromosome 7 and is a member of the RING finger protein family. The E3 ubiquitin ligase MKRN1 is closely linked to tumour development, but the exact mechanism needs to be elucidated. In this study, we aimed to investigate the specific mechanism and role of MKRN1 in colorectal cancer (CRC) development. METHODS: MKRN1 expression in CRC was analysed using the Cancer Cell Line Encyclopaedia and the Cancer Genome Atlas (TCGA) databases. Rectal tumour tissues were frozen to explore the MKRN1 expression in CRC and its clinical significance. The impact of MKRN1 on CRC cell proliferation and migration was observed using CCK8, colony formation, wound healing, and transwell assays. A combination of MKRN1 quantitative proteomics, ubiquitination modification omics analysis, and a string of in vitro and in vivo experiments revealed the potential mechanisms by which MKRN1 regulates CRC metastasis. RESULTS: MKRN1 expression was significantly elevated in CRC tissues compared to paracancerous tissues and was positively linked with prognosis (P < 0.01). MKRN1 downregulation inhibits CRC cell proliferation, migration, and invasion. Conversely, MKRN1 overexpression promotes the proliferation, migration, and invasion of CRC cells. Mechanistically, MKRN1 induces epithelial-mesenchymal transition (EMT) in CRC cells via ubiquitination and degradation of Smad nuclear-interacting protein 1 (SNIP1). Furthermore, SNIP1 inhibits transforming growth factor-ß (TGF-ß) signalling, and MKRN1 promotes TGF-ß signalling by degrading SNIP1 to induce EMT in CRC cells. Finally, using conditional knockout mice, intestinal lesions and metastatic liver microlesions were greatly reduced in the intestinal knockout MKRN1 group compared to that in the control group. CONCLUSIONS: High MKRN1 levels promote TGF-ß signalling through ubiquitination and degradation of SNIP1, thereby facilitating CRC metastasis, and supporting MKRN1 as a CRC pro-cancer factor. The MKRN1/SNIP1/TGF-ß axis may be a potential therapeutic target in CRC.

CXCR4 knockdown enhances sensitivity of paclitaxel via the PI3K/Akt/mTOR pathway in ovarian carcinoma.

Epithelial ovarian cancer (EOC) is the deadliest gynecological malignancy. EOC control remains difficult, and EOC patients show poor prognosis regarding metastasis and chemotherapy resistance. The aim of this study was to estimate the effect of CXCR4 knockdown-mediated reduction of cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT) stemness and enhancement of chemotherapy sensitivity in EOC. Mechanisms contributing to these effects were also explored. Our data showed distinct contribution of CXCR4 overexpression by dependent PI3K/Akt/mTOR signaling pathway in EOC development. CXCR4 knockdown resulted in a reduction in CSCs and EMT formation and enhancement of chemotherapy sensitivity in tumor cells, which was further advanced by blocking CXCR4-PI3K/Akt/mTOR signaling. This study also documented the critical role of silencing CXCR4 in sensitizing ovarian CSCs to chemotherapy. Thus, targeting CXCR4 to suppress EOC progression, specifically in combination with paclitaxel (PTX) treatment, may have clinical application value.

Current status about school health department settings and staff building of the centers for disease control and prevention in China / 中国学校卫生

Objective@#To learn about the construction and staffing of the school health system in Chinese institutions for disease prevention and control, and to provide basic information for the school health system, team capacity building and work development.@*Methods@#Electronic questionnaire was used to collect the setting and staffing of school health departments (including school health centers and departments/rooms) at the provincial, prefecture and county (district) levels in the centers for disease control and prevention. Statistical analysis was made on the proportion of school health, the number of staff and the characteristics such as age, education, major and working years in the provincial, prefecture and county (district) levels.@*Results@#Among the 3 313 institutions, the proportion of independent school health departments was 10.8%, and those of the provincial, prefecture and county (district) levels were 74.2%, 15.0%, and 9.6%, respectively. Among the institutions with separated department, the average number of staff members was 4.4, while the number of staff was 2.5. The average age of school health workers was 40.4 years old, and the proportion of male and female employees was 45.2% and 54.8%. The proportion of personnel who have been engaged in school health work for less than 5 years on average was as high as 65.1%. The majors of the staff were mainly public health ( 40.4 %), 54.0% of the provincial staff had a master s degree or above, and 47.8% and 58.7% of the staff at the prefecture and county (district) levels were junior college or below respectively.The proportion of provincial level personnel with intermediate and senior titles was 69.6%, and the proportion of municipal and countylevel personnel at the junior level and below was 52.2% and 56.2% respectively.@*Conclusion@#The proportion of independent school health departments within centers of disease control and prevention across China was low. There is a serious shortage of school health personnel, and there are problems such as low levels of education and professional titles, especially in county (district) level institutions. It is urgent to strengthen the construction of the school health system of the centers for disease control and prevention in China.

Current status about school health department settings and staff building of the centers for disease control and prevention in China / 中国学校卫生

Objective@#To learn about the construction and staffing of the school health system in Chinese institutions for disease prevention and control, and to provide basic information for the school health system, team capacity building and work development.@*Methods@#Electronic questionnaire was used to collect the setting and staffing of school health departments (including school health centers and departments/rooms) at the provincial, prefecture and county (district) levels in the centers for disease control and prevention. Statistical analysis was made on the proportion of school health, the number of staff and the characteristics such as age, education, major and working years in the provincial, prefecture and county (district) levels.@*Results@#Among the 3 313 institutions, the proportion of independent school health departments was 10.8%, and those of the provincial, prefecture and county (district) levels were 74.2%, 15.0%, and 9.6%, respectively. Among the institutions with separated department, the average number of staff members was 4.4, while the number of staff was 2.5. The average age of school health workers was 40.4 years old, and the proportion of male and female employees was 45.2% and 54.8%. The proportion of personnel who have been engaged in school health work for less than 5 years on average was as high as 65.1%. The majors of the staff were mainly public health ( 40.4 %), 54.0% of the provincial staff had a master s degree or above, and 47.8% and 58.7% of the staff at the prefecture and county (district) levels were junior college or below respectively.The proportion of provincial level personnel with intermediate and senior titles was 69.6%, and the proportion of municipal and countylevel personnel at the junior level and below was 52.2% and 56.2% respectively.@*Conclusion@#The proportion of independent school health departments within centers of disease control and prevention across China was low. There is a serious shortage of school health personnel, and there are problems such as low levels of education and professional titles, especially in county (district) level institutions. It is urgent to strengthen the construction of the school health system of the centers for disease control and prevention in China.

Crosstalk between CST and RPA regulates RAD51 activity during replication stress.

Replication stress causes replication fork stalling, resulting in an accumulation of single-stranded DNA (ssDNA). Replication protein A (RPA) and CTC1-STN1-TEN1 (CST) complex bind ssDNA and are found at stalled forks, where they regulate RAD51 recruitment and foci formation in vivo. Here, we investigate crosstalk between RPA, CST, and RAD51. We show that CST and RPA localize in close proximity in cells. Although CST stably binds to ssDNA with a high affinity at low ionic strength, the interaction becomes more dynamic and enables facilitated dissociation at high ionic strength. CST can coexist with RPA on the same ssDNA and target RAD51 to RPA-coated ssDNA. Notably, whereas RPA-coated ssDNA inhibits RAD51 activity, RAD51 can assemble a functional filament and exhibit strand-exchange activity on CST-coated ssDNA at high ionic strength. Our findings provide mechanistic insights into how CST targets and tethers RAD51 to RPA-coated ssDNA in response to replication stress.

GADD45α alleviates the CDDP resistance of SK-OV3/cddp cells via redox-mediated DNA damage.

Epithelial ovarian cancer has the highest mortality rate of all malignant ovarian cancer types. Great progress has been made in the treatment of ovarian cancer in recent years. However, drug resistance has led to a low level of 5-year survival rate of epithelial ovarian cancer, and the molecular mechanism of which remains unknown. The aim of the present study was to identify the role of redox status in the cisplatin (CDDP) resistance of ovarian cancer. CDDP-resistant SK-OV3 (SK-OV3/cddp) cells were prepared and their reactive oxygen species and glutathione levels were investigated. The effects of hydrogen peroxide on the CDDP sensitivity of the SK-OV3/cddp cells and their expression levels of the redox-associated protein growth arrest and DNA damage 45a (GADD45α) were also investigated. In addition, the impact of GADD45α overexpression on cell viability was evaluated in vitro and in vivo, and the levels of Ser-139 phosphorylated H2A histone family member X (γ-H2AX), which is associated with DNA damage, were detected. The results suggested that redox status affected the drug resistance of the ovarian cancer cells by increasing the expression of GADD45α. The overexpression of GADD45α reversed the CDDP resistance of the SK-OV3/cddp cells and increased the level of γ-H2AX. In conclusion, GADD45α alleviated the CDDP resistance of SK-OV3/cddp cells via the induction of redox-mediated DNA damage.

Oct4 Regulates the Transition of Cancer Stem-Like Cells to Tumor Endothelial-Like Cells in Human Liver Cancer.

Octamer-binding transcription factor 4 (Oct4) has been recently implicated as a proangiogenic regulator in several induced pluripotent stem cells (iPSCs), however, its role in cancer stem-like cells (CSCs) remain unclear. We report here that Oct4 participates in tumor vasculogenesis in liver CSCs (LCSCs). We identify that LCSCs possess the potential of endothelial trans-differentiation under endothelial induction, present endothelial specific markers and their functions in vitro, and participate in neovasculogenesis in vivo. The knockdown of the Oct4A by short hairpin RNA (shRNA) in LCSCs represses endothelial trans-differentiation potential, but induces endothelial lineage-restricted differentiation, the latter is positively regulated by Oct4B1. Furthermore, Oct4 regulates vasculogenesis in LCSCs may be via the AKT-NF-κB-p65 signaling pathway. This work reveals Oct4, which is a crucial regulator, plays a critical role in tumor endothelial-like cells transition of LCSCs through Oct4A and Oct4B1 by different ways. The simultaneous inhibition of both the isoforms of Oct4 is hence expected to help regress neovascularization derived from CSCs. Our findings may provide insights to the possible new mechanisms of tumor vasculogenesis for primary liver cancer.

Microcephaly family protein MCPH1 stabilizes RAD51 filaments.

Microcephalin 1 (MCPH1) was identified from genetic mutations in patients with primary autosomal recessive microcephaly. In response to DNA double-strand breaks (DSBs), MCPH1 forms damage-induced foci and recruits BRCA2-RAD51 complex, a key component of the DSB repair machinery for homologous recombination (HR), to damage sites. Accordingly, the efficiency of HR is significantly attenuated upon depletion of MCPH1. The biochemical characteristics of MCPH1 and its functional interaction with the HR machinery had remained unclear due to lack of highly purified MCPH1 recombinant protein for functional study. Here, we established a mammalian expression system to express and purify MCPH1 protein. We show that MCPH1 is a bona fide DNA-binding protein and provide direct biochemical analysis of this MCPH family protein. Furthermore, we reveal that MCPH1 directly interacts with RAD51 at multiple contact points, providing evidence for how MCPH1 physically engages with the HR machinery. Importantly, we demonstrate that MCPH1 enhances the stability of RAD51 on single-strand DNA, a prerequisite step for RAD51-mediated recombination. Single-molecule tethered particle motion analysis showed a ∼2-fold increase in the lifetime of RAD51-ssDNA filaments in the presence of MCPH1. Thus, our study demonstrates direct crosstalk between microcephaly protein MCPH1 and the recombination component RAD51 for DSB repair.

Base-iodine-promoted metal-catalyst-free reactions of [60]fullerene with ß-keto esters for the selective formation of [60]fullerene derivatives.

In this study, methanofullerenes and 2',3'-dihydrofuran C60 derivatives were selectively synthesized in high yields via the reactions of C60 with ß-keto esters under mild conditions by controlling the addition sequence and molar ratio of iodine and base. The structures of the products were determined by spectroscopic characterization. Moreover, a possible reaction mechanism for the selective formation of fullerene derivatives was proposed.

Pseudoginsenoside-F11 attenuates cerebral ischemic injury by alleviating autophagic/lysosomal defects.

AIMS: Pseudoginsenoside-F11 (PF11), an ocotillol-type ginsenoside, has been reported to exert wide-ranging neuroprotective properties. The aim of this study was to investigate the effect and potential mechanisms of PF11 on the autophagic/lysosomal pathway following ischemic stroke. METHODS: Male Sprague-Dawley rats underwent permanent middle cerebral artery occlusion (pMCAO). Cerebral ischemia outcome, TUNEL staining, Fluoro-Jade B staining were carried out 24 hours poststroke. The autophagic/lysosomal-related proteins were measured. RESULTS: A single administration of PF11 significantly decreased the infarct area, reduced the brain water content, and improved neurological functions, even 4 hours after the onset of pMCAO. Meanwhile, PF11 lessened the ischemic insult-mediated loss of neurons and activation of astrocytes and microglia. Furthermore, PF11 attenuated pMCAO-induced accumulations of autophagosomes and apoptosis. We further observed a remarkable effect of PF11 in reversing the ischemic insult-induced accumulation of autophagosomes (LC3-II) and abnormal aggregation of autophagic proteins (SQSTM1 and ubiquitin). Furthermore, PF11 was capable of improving lysosomal function and lysosome/autophagosome fusion following pMCAO, and this change was reversed by the lysosomal inhibitor chloroquine. Also, the improvement of ischemic outcome and the antiapoptotic effect induced by PF11 was reversed by CQ. CONCLUSION: These findings indicate that the autophagic flux is impaired in a rat model of pMCAO, and that PF11 exerts an excellent protective effect against ischemic stroke by alleviating autophagic/lysosomal defects.