Background: Triple negative breast cancer (TNBC), a special subtype of breast cancer, is characterized by high recurrence, mortality and few treatments. To date, the key factors contributing to TNBC progression have not been fully identified. In the current study, we found a TNBC-related circular RNA (circRNA), circ-PGAP3, and explored its biological function, clinical significance and potential mechanism of action. Materials and Methods: The functional assay was carried out using CCK-8, colony formation and Transwell invasion assays. RIP, RNA pull-down and luciferase reporter assays were used to test the correlation between circ-PGAP3, miR-330-3p and Myc. The animal model was employed to verify the function of circ-PGAP3 in vivo. Results: Circ-PGAP3 expression was significantly increased in TNBC tissues. High circ-PGAP3 was closely associated with large tumor size, lymph node metastasis, later TNM stage and dismal outcome. Through performing a series of in vitro and in vivo experiments, we found that circ-PGAP3 promoted TNBC cell growth and metastasis via sponging and inhibiting miR-330-3p, resulting in the upregulation of proto-oncogene Myc. Importantly, circ-PGAP3 expression was positively correlated with the Myc protein level but negatively correlated with miR-330-3p expression in TNBC tissues. Moreover, silencing of miR-330-3p or overexpression of Myc could effectively rescue the weakened malignant phenotype induced by circ-PGAP3 knockdown. Conclusion: Our results unveil the important driving role of circ-PGAP3 in TNBC development and progression, which provides a candidate therapeutic target for TNBC patients.

Interleukin-12 (IL-12) serves an important role in immune responses and antitumor activity. The study of the association between autophagy and cancer cells remains controversial. The present study aimed to investigate the effect of IL‑12 on autophagy in the human breast cancer cell lines MDA‑MB‑231 and MCF‑7, and the possible molecular mechanism. Breast cancer cells were treated with different concentrations of recombinant IL‑12. The expression of the autophagy-associated protein microtubule‑associated protein light chain 3 (LC3) was determined using western blot analysis, fluorescein isothiocyanate‑labeled LC3 was detected using fluorescence microscopy and autophagosomes were examined using transmission electron microscopy. Alterations in the phosphatidylinositol 3‑kinase/Rac‑α serine/threonine protein kinase (PI3K/Akt) and 5'‑AMP‑activated protein kinase subunit β‑1 (AMPK) pathways, in addition to pathway‑associated proteins, were detected using western blotting, following treatment with IL‑12 and pretreatment with the PI3K/Akt activator insulin‑like growth factor or the AMPK inhibitor compound C. It was observed that IL‑12 was able to upregulate the expression of the autophagy‑associated protein LC3 in a concentration‑ and time‑dependent manner, and induce the formation of autophagosomes in the two cell lines, and that the above effects involved the inhibition of the PI3K/Akt signaling pathway and the activation of the AMPK signaling pathway.

Prostate cancer (PCa) is one of the most prevalent cancers in men worldwide, and hormonal therapy plays a key role in the treatment of PCa. However, the drug resistance of hormonal therapy makes it urgent and necessary to identify novel targets for PCa treatment. Herein, dual-specificity tyrosine phosphorylation-regulated kinase 2 (DYRK2) is found and confirmed to be highly expressed in the PCa tissues and cells, and knock-down of DYRK2 remarkably reduces PCa burden in vitro and in vivo. On the base of DYRK2 acting as a promising target, we further discover a highly selective DYRK2 inhibitor YK-2-69, which specifically interacts with Lys-231 and Lys-234 in the co-crystal structure. Especially, YK-2-69 exhibits more potent anti-PCa efficacy than the first-line drug enzalutamide in vivo. Meanwhile, YK-2-69 displays favorable safety properties with a maximal tolerable dose of more than 10,000 mg/kg and pharmacokinetic profiles with 56% bioavailability. In summary, we identify DYRK2 as a potential drug target and verify its critical roles in PCa. Meanwhile, we discover a highly selective DYRK2 inhibitor with favorable druggability for the treatment of PCa.

Aim: CDK4 and 6 are the key initiators in the transition from G1 to S phase in the cell cycle; thus, inhibition of CDK4/6 is a promising strategy for cancer treatment. Materials & methods: The Specs database and an in-house library were screened via the pharmacophore model and LibDock protocol and then the retrieved hits were clustered into 100 clusters. The CDK4/6 inhibitory activity of selected compounds was evaluated by CDK enzymatic assays, followed by chemical optimization of the top hit compound. Results & conclusion: The integration of pharmacophores and molecular docking offered us an effective method to discover the novel CDK4/6 inhibitor 10 and further chemical optimization led to the highly selective and potent CDK4/6 inhibitor 18, which exhibited potential for the treatment of multiple myeloma.

A series of novel 2-chloro-3-(1H-benzo[d]imidazol-2-yl)quinoline derivatives were designed and synthesized as antitumor agents under the combination principle. The antitumor activity and mechanisms were then evaluated.