BackgroundThymidylate synthase (TYMS) is a successful chemotherapeutic target for anticancer therapy. Numerous TYMS inhibitors have been developed and used for treating gastrointestinal cancer now, but they have limited clinical benefits due to the prevalent unresponsiveness and toxicity. It is urgent to identify a predictive biomarker to guide the precise clinical use of TYMS inhibitors.MethodsGenome-scale CRISPR-Cas9 knockout screening was performed to identify potential therapeutic targets for treating gastrointestinal tumours as well as key regulators of raltitrexed (RTX) sensitivity. Cell-based functional assays were used to investigate how MYC regulates TYMS transcription. Cancer patient data were used to verify the correlation between drug response and MYC and/or TYMS mRNA levels. Finally, the role of NIPBL inactivation in gastrointestinal cancer was evaluated in vitro and in vivo.FindingsTYMS is essential for maintaining the viability of gastrointestinal cancer cells, and is selectively inhibited by RTX. Mechanistically, MYC presets gastrointestinal cancer sensitivity to RTX through upregulating TYMS transcription, supported by TCGA data showing that complete response cases to TYMS inhibitors had significantly higher MYC and TYMS mRNA levels than those of progressive diseases. NIPBL inactivation decreases the therapeutic responses of gastrointestinal cancer to RTX through blocking MYC.InterpretationOur study unveils a mechanism of how TYMS is transcriptionally regulated by MYC, and provides rationales for the precise use of TYMS inhibitors in the clinic.FundingThis work was financially supported by grants of (2016YFC1302400), (16JC1406200), (81872890, 81322034, 81372346) and (QYZDB-SSW-SMC034, XDA12020210).

cir-ITCH, a well-known tumor-suppressive circular RNA, plays a critical role in different cancers. However, its expression and functional role in prostate cancer (PCa) are unclear. Herein, we explored the potential mechanism and tumor-inhibiting role of cir-ITCH in PCa. Using reverse transcriptase polymerase chain reaction assay, we analyzed the expression of cir-ITCH in PCa and paired adjacent nontumor tissue samples resected during surgical operation, as well as in two cell lines of human PCa (LNCaP and PC-3) and the immortalized normal prostate epithelial cell line (RWPE-1). Cell viability and migration of PCa cell lines were evaluated using CCK-8 and wound-healing assays. Expression of key proteins of the Wnt/β-catenin and PI3K/AKT/mTOR pathways was detected using western blotting. We found that cir-ITCH expression was typically downregulated in the tissues and cell lines of PCa compared to that in the peritumoral tissue and in RWPE-1 cells, respectively. The results showed that cir-ITCH overexpression significantly inhibits the proliferation, migration, and invasion of human PCa cells and that reciprocal inhibition of expression occurred between cir-ITCH and miR-17. Proteins in the Wnt/β-catenin and PI3K/AKT/mTOR pathways were downregulated by overexpression of cir-ITCH both in androgen receptor-positive LNCaP cells and androgen receptor-negative PC-3 cells. Taken together, these data demonstrated that cir-ITCH plays a tumor-suppressive role in human PCa cells, partly through the Wnt/β-catenin and PI3K/AKT/mTOR pathways. Thus, cir-ITCH may serve as a novel therapeutic target for the treatment of PCa, especially castration-resistant prostate cancer.

Bladder cancer is one of the most common malignant tumors in the urinary system with high mortality and morbidity. Evidence revealed that bergenin could affect the development of cancer. Here, we aimed to investigate the effect of bergenin on bladder cancer progression and its mechanism. The effect of bergenin on cell function was first detected, followed by assessing the changes of the epithelial‐mesenchymal transition (EMT) in bergenin‐treated cells. The effect of bergenin on peroxisome proliferator‐activated receptor γ (PPARγ)/phosphatase and tensin homolog (PTEN)/Akt signal pathway was measured by Western blotting, followed by the rescue experiments. The results showed that bergenin treatment significantly decreased cell viability and increased G1 phase arrest, accompanied by reduced expression of Ki67, cycling D1, and cycling B1 in bladder cancer cells. Apoptosis was induced by bergenin in bladder cancer cells, as evidenced by increased Bax and cleaved caspase 3 protein levels and decreased Bcl‐2 level in bergenin‐treated cells. Meanwhile, the inhibition of the invasion, migration, and EMT was also observed in bergenin‐treated cells. Mechanism studies showed that bergenin treatment could activate PPARγ/PTEN/Akt signal pathway, as evidence by the increased nucleus PPARγ and phosphatase and tensin homolog (PTEN) expression and decreased Akt expression. Moreover, PPARγ inhibitor administration inverted the effects of bergenin on bladder cancer cell function, including the proliferation, apoptosis, invasion, and migration in bladder cancer cells. Our findings revealed that bergenin could inhibit bladder cancer progression via activating the PPARγ/PTEN/Akt signal pathway, indicating that bergenin may be a potential therapeutic medicine for bladder cancer treatment.

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The purpose of this study was to investigate the possibility that oxidative stress was involved in danofloxacin-induced toxicity in renal tubular cells epithelial cell line (LLC-PK1). Confluent LLC-PK1 cells were incubated with various concentrations of danofloxacin. The extent of oxidative damage was assessed by measuring the reactive oxygen species (ROS) level, lipid peroxidation, cell apoptosis and antioxidative enzyme activities. Danofloxacin induced a concentration-dependent increase in the ROS production, not even cytotoxic conditions. Similarly, danofloxacin caused an about 4 times increase in the level of thiobarbituric acid reactive substances at the concentration of 400 lM for 24 hr, but it did not induce cytotoxicity and apoptosis. Antioxidant enzymes activities, such as superoxide dismutase (SOD) and catalase (CAT), were increased after treatment with 100, 200 and 400 lM of danofloxacin for 24 hr. The activity of glutathione peroxidase (GPX) was significantly decreased in a concentration-dependent manner. In addition, ROS production, lipid peroxidation and GPX decline were inhibited by additional glutathione and N-acetyl cysteine. These data suggested that danofloxacin could not induce oxidative stress in LLC-PK1 cells at the concentration (≤400 lM) for 24 hr. The increase levels of ROS and lipid peroxidation could be partly abated by the increase activities of SOD and CAT.

Transposable elements (TEs) through evolutionary exaptation have become an integral part of the human genome, offering ample regulatory sequences and shaping chromatin 3D architecture. While the functional impacts of TE-derived sequences on early embryogenesis have been recognized, their roles in malignancy are only starting to emerge. Here we show that many TEs, especially the pluripotency-related human endogenous retrovirus H (HERVH), are abnormally activated in colorectal cancer (CRC) samples. Transcriptional upregulation of HERVH is associated with mutations of several tumor suppressors, particularly ARID1A. Knockout of ARID1A in CRC cells leads to increased transcription at several HERVH loci, which involves compensatory contribution by ARID1B. Suppression of HERVH in CRC cells and patient-derived organoids impairs tumor growth. Mechanistically, HERVH transcripts colocalize with nuclear BRD4 foci, modulating their dynamics and co-regulating many target genes. Altogether, we uncover a critical role for ARID1A in restraining HERVH, whose abnormal activation can promote tumorigenesis by stimulating BRD4-dependent transcription.

Mitosis and endocytosis are two fundamental cellular processes essential for maintaining a eukaryotic life. Mitosis partitions duplicated chromatin enveloped in the nuclear membrane into two new cells, whereas endocytosis takes in extracellular substances through membrane invagination. These two processes are spatiotemporally separated and seemingly unrelated. However, recent studies have uncovered that endocytic proteins have moonlighting functions in mitosis, and mitotic complexes manifest additional roles in endocytosis. In this review, we summarize important proteins or protein complexes that participate in both processes, compare their mechanism of action, and discuss the rationale behind this multifunctionality. We also speculate on the possible origin of the functional reciprocity from an evolutionary perspective. An introduction to mitosis and endocytic pathwaysEukaryotic cells rely on endocytosis to uptake extracellular materials and their own plasma membrane components, in order to maintain homeostasis and respond to the varying environment [1-3]; they use the process of mitosis to achieve self-duplication and cell fate specification when differentiating [1,4]. These two Abbreviations AP2, adaptor protein-2; APC/C, anaphase-promoting complex/cyclosome; CCP, clathrin-coated pit; CCV, clathrin-coated vesicle; CHC, clathrin heavy chains; ch-TOG, colonic and hepatic tumor overexpressed gene; CLC, clathrin light chain; CME, clathrin-mediated endocytosis; CPC, chromosome passenger complex;

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