Hepatocellular carcinoma (HCC) is the second leading cause of cancer related-death. As a major common regulator of numerous cancer-driving pathways and a unique therapeutic target, the prolyl isomerase Pin1 is overexpressed in a majority of HCCs, whereas the mechanism underlying Pin1 overexpression remains elusive. Here we find that miR-140-5p inhibits HCC by directly targeting Pin1 to block multiple cancer-driving pathways. Bioinformatics analysis, miRNA binding and functional assays identify that miR-140-5p directly interacts with the 3′UTR of Pin1 and inhibits Pin1 translation. Furthermore, like stable Pin1 knockdown, moderate overexpression of miR-140-5p not only eliminates Pin1, but also inhibits cells growth and metastasis. Importantly, these effects of miR-140-5p are largely rescued by reconstitution of Pin1. Moreover, miR-140-5p inhibits multiple Pin1-dependent cancer pathways and suppresses tumor growth in mice. The clinical significance of these findings has been substantiated by the demonstrations that miR-140-5p is frequently down-regulated and inversely correlated with Pin1 overexpression in HCC tissues and cell lines. Given prevalent miR-140-5p downregulation in other cancers and major impact of Pin1 overexpression on activating numerous cancer-driving pathways including global miRNA downregulation, the miR-140-5p/Pin1 axis may play a major role in tumorigenesis and offer promising therapeutic targets for HCC and other cancers.

The human prolyl isomerase PIN1, best known for its association with carcinogenesis, has recently been indicated in the disease of pancreatic ductal adenocarcinoma (PDAC). However, the functions of PIN1 and the feasibility of targeting PIN1 in PDAC remain elusive. For this purpose, we examined the expression of PIN1 in cancer, related paracarcinoma and metastatic cancer tissues by immunohistochemistry and analyzed the associations with the pathogenesis of PDAC in 173 patients. The functional roles of PIN1 in PDAC were explored in vitro and in vivo using both genetic and chemical PIN1 inhibition. We showed that PIN1 was upregulated in pancreatic cancer and metastatic tissues. High PIN1 expression is significantly association with poor clinicopathological features and shorter overall survival and disease‐free survival. Further stratified analysis showed that PIN1 phenotypes refined prognostication in PDAC. Inhibition of PIN1 expression with RNA interference or with all trans retinoic acid decreased not only the growth but also the migration and invasion of PDAC cells through regulating the key molecules of multiple cancer‐driving pathways, simultaneously resulting in cell cycle arrest and mesenchymal‐epithelial transition in vitro. Furthermore, genetic and chemical PIN1 ablation showed dramatic inhibition of the tumorigenesis and metastatic spread and then reduced the tumor burden in vivo. We provided further evidence for the use of PIN1 as a promising therapeutic target in PDAC. Genetic and chemical PIN1 ablation exerted potent antitumor effects through blocking multiple cancer‐driving pathways in PDAC. More potent and specific PIN1 targeted inhibitors could be exploited to treat this aggressive cancer.

TCP1, one of the subunits of molecular chaperone containing tailless complex polypeptide 1 (CCT) (CCT1), maybe play an essential role in cell proliferation and tumorigenesis. However, the biological functions and the underlying mechanisms of TCP1 in tumors are not fully understood. Here, we found that TCP1 levels increased with successive generations of xenografted tumors and were associated with the tumorigenicity of HL-60 cells. TCP1 expression was significantly higher in de novo and recurrent leukemia clinical samples and in various solid tumor tissues than in their related normal tissues. High expression of TCP1 was significantly associated with poor outcomes in patients with pancreatic ductal adenocarcinoma (PDAC) and HCC. Functional assays and mechanistic studies revealed that TCP1 suppression not only decreased the proliferation and invasion of cancer cells in vitro but also inhibited tumor growth and metastatic spread in vivo. Ubiquitination assays and mechanistic studies revealed that TCP1 regulated the stability of c-Myc through the AKT/GSK-3β and ERK signaling pathways. Moreover, TCP1 knockin (TCP1-KI) mice, which generated by CRISPR/Cas9-mediated genome engineering, dramatically facilitated the occurrence of DEN-induced HCC. Our results demonstrate a novel mechanism of TCP1 regulation in multiple malignant tumors, and targeting TCP1 may provide new therapeutic strategies for the cancer treatment.