Peptide modulators targeting protein-protein interactions (PPIs) exhibit greater potential than small-molecule drugs in several important aspects including facile modification and relative large contact surface area. Stabilized peptides constructed by variable chemistry methods exhibit improved peptide stability and cell permeability compared to that of the linears. Herein, we designed a stabilized peptide-based proteolysis-targeting chimera (PROTAC) targeting estrogen receptor α (ERα) by tethering an N-terminal aspartic acid cross-linked stabilized peptide ERα modulator (TD-PERM) with a pentapeptide that binds the Von Hippel-Lindau (VHL) E3 ubiquitin ligase complex. The resulting heterobifunctional peptide (TD-PROTAC) selectively recruits ERα to the VHL E3 ligase complex, leading to the degradation of ERα in a proteasome-dependent manner. Compared with the control peptides, TD-PROTAC shows significantly enhanced activities in reducing the transcription of the ERα-downstream genes and inhibiting the proliferation of ERα-positive breast cancer cells. In addition, in vivo experiments indicate that TD-PROTAC leads to tumor regression in the MCF-7 mouse xenograft model. This work is a successful attempt to construct PROTACs based on cell-permeable stabilized peptides, which significantly broadens the chemical space of PROTACs and stabilized peptides.

Gastric cancer (GC) is a common disease globally with high mortality rate. It is therefore necessary to develop novel therapies targeting specific events in the pathogenesis of GC. Some hnRNP family members are involved in multiple cancer biological behaviors. However, the potential function and mechanism of hnRNPR, a new molecule of hnRNP family in GC remains unknown. We found that the expression of hnRNPR was significantly overexpressed in multiple cancers compared to the normal tissues. Functionally, hnRNPR promoted cancer cell proliferation, migration, and invasion. Knockdown of hnRNPR in two type mice models, with two types of tumors models decreased the tumor aggressiveness and metastasis. Mechanistically, hnRNPR targeted oncogenic pathways by stabilizing the expression of CCNB1 and CENPF mRNA level. Knockdown of CCNB1 and CENPF abolished the hnRNPR-induced cell growth and invasion, respectively. Furthermore, the protein level of hnRNPR in the tumor was positively correlated with the expression of CCNB1 and CENPF in clinical samples. Together, these results indicate that overexpression of hnRNPR promoted the aggressiveness of GC by increasing the mRNA expression of CCNB1 and CENPF. HnRNPR-CCNB1/CENPF axis may be a potential therapeutic target for GC treatment.

Background/Aims: Breast cancer is a common cause of cancer mortality throughout the world. The cross-talk between cancer cells and interstitial cells exerts significant effects on neoplasia and tumor development and is modulated in part by chemokines. CXC is one of four chemokine families involved in mediating survival, angiogenesis, and immunosensitization by chemoattracting leukocytes, and it incentivizes tumor cell growth, invasion and metastasis in the tumor microenvironment. However, the differential expression profiles and prognostic values of these chemokines remains to be elucidated. Methods: In this study, we compared transcriptional CXC chemokines and survival data of patients with breast carcinoma (BC) using the ONCOMINE dataset, Kaplan-Meier Plotter, TCGA and cBioPortal. Results: We discovered increased mRNA levels for CXCL8/10/11/16/17, whereas mRNA expression of CXCL1/2/3/4/5/6/7/12/14 was lower in BC patients compared to non-tumor tissues. Kaplan-Meier plots revealed that high mRNA levels of CXCL1/2/3/4/5/6/7/12/14 correlate with relapse-free survival (RFS) in all types of BC patients. Conversely, high CXCL8/10/11 predicted worse RFS in BC patients. Significantly, high transcription levels of CXCL9/12/13/14 conferred an overall survival (OS) advantage in BC patients, while high levels of CXCL8 demonstrated shorter OS in all BC sufferers. Conclusions: Integrative bioinformatics analysis suggests that CXCL8/12/14 are potential suitable targets for precision therapy in BC patients compared to other CXC chemokines.

An easily accessible fluorescent dye, FEB, which has a high fluorescence quantum yield and is suitable for in vivo tumour imaging is reported.

Direct inhibition of the protein-protein interaction of ERα and its endogenous coactivators with a cell permeable stabilized peptide may offer a novel, promising strategy for combating ERα positive breast cancers. Here, we report the co-crystal structure of a helical peptide stabilized by a N-terminal unnatural cross-linked aspartic acid (TD) in complex with the ERα ligand binding domain (LBD). We designed a series of peptides and peptide 6 that showed direct and high-affinity binding to ERα with selective antiproliferative activity in ERα positive breast cancer cells. The co-crystal structure of the TD-stabilized peptide 6 in complex with ERα LBD further demonstrates that it forms an α helical conformation and directly binds at the coactivator binding site of ERα. Further studies showed that peptide 6 could potently inhibit cellular ERα's transcriptional activity. This approach demonstrates the potential of TD stabilized peptides to modulate various intracellular protein-protein interactions involved in a range of disorders.