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Additional file 2: Figure S2. The body weight of the mice in these four groups.

Additional file 1: Figure S1. Western blot analysis of Snail levels in KLE and AN3CA cells with SLERT knockdown.

Cervical cancer (CC) is still an intractable disease that seriously affects women's health. Elucidating its pathogenesis will bring new targets for clinical treatment. Circular RNA (circRNA) is an endogenous RNA that has recently been reported to be closely related to cancer progression and development. In the current study, by performing in silico analysis and qRT-PCR assay, we found a circRNA derived from PGAP3, referred as circ-PGAP3 (hsa_circ_0106800, chr17:37843549-37844086), which was significantly downregulated in CC tissues. Low circ-PGAP3 was closely linked to poor prognosis. And overexpression of circ-PGAP3 significantly reduced CC cell proliferation in vitro and tumor growth in vivo. In terms of mechanism, circ-PGAP3 was transcriptionally elevated by p53, a well-recognized tumor suppressor, and circ-PGAP3 was located in the cytoplasm where sponged miR-769-5p to increase the levels of p53 and its downstream targets. Importantly, the regulatory feedback loop of circ-PGAP3/p53 was also confirmed in vivo. Overall, our data clearly expounded the tumor-inhibiting role of circ-PGAP3 in CC, circ-PGAP3 repressed CC tumorigenesis via regulating the miR-769-5p/p53 axis. Therefore, restoration of circ-PGAP3 may be a promising therapeutic target for this thorny disease.

Hailing Cheng,1,* Ning Wang,1,* Jun Tian,1 Yanyun Li,1 Lu Ren,1 Zhenyu Shi2 1Department of Obstetrics and Gynecology, Huaihe Hospital of Henan University, Kaifeng, Henan, People’s Republic of China; 2Henan Medical School, Henan University, Kaifeng, Henan, People’s Republic of China*These authors contributed equally to this workCorrespondence: Zhenyu ShiHenan Medical School, Henan University, Section 229, North of Jinming Avenue, Kaifeng City, Henan Province, People’s Republic of ChinaTel +86-371-22922953Email xzmkra@163.comBackground: Circular RNAs (circRNAs) are significant molecular targets in various types of human cancers. The functional mechanism of circRNA_0025033 (circ_0025033) in ovarian cancer (OC) was discussed in the current report.Methods: The quantitative real-time polymerase chain reaction (qRT-PCR) was used for determining the circ_0025033 and microRNA-330-5p (miR-330-5p) levels. Cell Counting Kit-8 (CCK-8) and transwell assays were separately exploited to analyze cell viability and migration/invasion. Cell apoptosis was assessed using flow cytometry. The protein levels of epithelial–mesenchymal transition (EMT)-related makers and kallikrein-related peptidase 4 (KLK4) were measured by Western blotting. The target combination was confirmed by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) and RNApull-down assays. And the effect of circ_0025033 on OC in vivo was explored via xenograft tumor assay.Results: Circ_0025033 was overexpressed in OC tissues and cells. Circ_0025033 knockdown inhibited OC cell viability, migration, invasion and EMT while expedited apoptosis. MiR-330-5p was a target of circ_0025033 and circ_0025033 regulated OC cellular behaviors by sequestering miR-330-5p. Moreover, miR-330-5p targeted KLK4 and circ_0025033 affected the KLK4 expression by sponging miR-330-5p. And miR-330-5p functioned as a tumor inhibitor in OC via targeting KLK4. In vivo, circ_0025033 promoted OC growth by the miR-330-5p/KLK4 axis.Conclusion: This study demonstrated that circ_0025033 contributed to the progression of OC via the miR-330-5p/KLK4 axis and might be a candidate target in the identification and treatment of OC.Keywords: circ_0025033, ovarian cancer, miR-330-5p, KLK4

A practical strategy was proposed and successfully used to design and develop an isoform-specific probe for a given enzyme., The development of isoform-specific probe(s) for a target enzyme with multiple homologs is always challenging. Herein, a practical strategy was used to design and develop an isoform-specific probe for CYP1A1, a key cytochrome P450 isoenzyme involved in xenobiotic metabolism and bioactivation. On the basis of the subtle differences in 3D structure and substrate preference between CYP1A1 and its homolog CYP1A2, we proposed that it was possible to design a CYP1A1-specific probe via local modification of the reaction site on known CYP1A substrates. To validate this hypothesis, 4-hydroxy-1,8-naphthalimide (HN) was selected as the basic fluorophore due to its excellent optical properties, while a series of O-alkylated HN derivatives were prepared to evaluate their specificity towards CYP1A1. Our results revealed that the introduction of a chloroethyl to HN could get the best isoform selectivity towards CYP1A1 over other CYPs including CYP1A2. The newly developed probe NBCeN exhibited excellent specificity, high sensitivity, and a ratiometric fluorescence response following CYP1A1-catalyzed O-dechloroethylation. NBCeN was successfully used to real-time monitor the activity of CYP1A1 in complex biological samples and to rapidly screen CYP1A1 modulators in living systems. NBCeN could also be used for two-photon imaging of intracellular CYP1A1 in living cells and tissues with high ratiometric imaging resolution and deep tissue penetration. All these findings demonstrated that local modification of non-specific substrates was a practical strategy to develop an isoform-specific probe for a target isoenzyme, while NBCeN could serve as a specific imaging tool to explore the biological functions of CYP1A1 in complex biological systems.

PIK3CA gain-of-function mutations are a common oncogenic event in human malignancy, making phosphatidylinositol 3-kinase (PI3K) a target for cancer therapy. Despite the promise of targeted therapy, resistance often develops, leading to treatment failure. To elucidate mechanisms of resistance to PI3K-targeted therapy, we constructed a mouse model of breast cancer conditionally expressing human PIK3CA(H1047R). Notably, most PIK3CA(H1047R)-driven mammary tumors recurred after PIK3CA(H1047R) inactivation. Genomic analyses of recurrent tumors revealed multiple lesions, including focal amplification of Met or Myc (also known as c-Met and c-Myc, respectively). Whereas Met amplification led to tumor survival dependent on activation of endogenous PI3K, tumors with Myc amplification became independent of the PI3K pathway. Functional analyses showed that Myc contributed to oncogene independence and resistance to PI3K inhibition. Notably, PIK3CA mutations and c-MYC elevation co-occur in a substantial fraction of human breast tumors. Together, these data suggest that c-MYC elevation represents a potential mechanism by which tumors develop resistance to current PI3K-targeted therapies.