Pattern recognition receptor mediated innate immune response requires a Rif-dependent pathway

Small GTPases play critical roles in cell morphology, movement, and adhesion by dynamic regulation of actin cytoskeleton. The small Rho GTPase Rif/RhoF (Rho in filopodia) regulates the formation of filopodia and stress fibers in cells. Rif is highly expressed in a number of cell types in the immune system; however, it's role in immune system function is unclear. In this research, we found that Rif expression is necessary for NF-κB activation in primary immune cells, and mature dendritic cell (mature DCs) induced from Bone Marrow-Derived Dendritic Cells (BMDCs) isolated from Rif knock out (Rif KO) mice displayed impaired degradation of I-κBα, as well as reduced TNF-α secretion and p38 MAPK phosphorylation under LPS stimulation. Interestingly, we revealed that TLR agonists, such as LPS and poly (I:C), as well as bacterial virulence factor SopE could induce a transient increase in Rif activation in monocytes THP-1 cells. Furthermore, Rif was found to be an integral part of the TLR4, TLR3 and nodosome signaling complex. We further identified Src tyrosine kinases as upstream activator of Rif in both bacterial and viral induced immune responses. Moreover, activated Rif induces activation of transcription factors, such as NF-κB, AP-1 and IRF-3, and mediates inflammation through secretion of IL-6, IL-8 or TNFα. Rif activation by PRRs contributes in a variety of ways to protective host responses against invading microbes. Taken together, this study reveals that Rif is indispensable for both extracellular and intracellular pattern-recognition receptor-mediated innate immune responses. Rif possess broad anti-pathogenic effect and understanding of the molecular mechanisms by which this small Rho GTPase interferes with innate immune system will be beneficial to develop therapies against infectious agents.

The antihyperlipidemic drug potassium piperonate impairs the migration and tumorigenesis of breast cancer cells via the upregulation of miR-31

Background

Breast cancer is the second cause of cancer death in women, and tumor metastasis is the primary cause of mortality. Due to the involvement of many regulatory molecules and signaling pathways, the occurrence and development of metastases needs to be further studied. MicroRNAs (miRNAs) are ubiquitously expressed small non-coding RNAs that have been shown to play an important role in the diagnosis and treatment of many diseases, as well as representing an attractive candidate for metastasis control. In this study, we investigated the mechanism of potassium piperonate (GBK) in impairing breast cancer cell invasion and metastasis by targeting miR-31.

Methods

Breast cancer cells, either treated with GBK or left untreated, were assessed for migration and invasion capacities using wound healing and transwell assays. GBK-targeted miRNAs were identified and verified using RT-qPCR. Western blotting was used to validate the changes in expression levels of miR-31-targeted genes. Methylation specific PCR was performed to detect the effect of GBK on the methylation levels of the lncRNA LOC554202 host gene. The synergistic effect of GBK and the chemotherapy drug cisplatin (DDP) on breast cancer cells was verified using cell proliferation, colony formation, and RT-qPCR assays in vitro, and the tumor xenograft model in vivo.

Results

We found that miR-31 was the main target of GBK. GBK treatment affected the epigenetic modification at CpG sites by downregulating DNA methyltransferases. Thus, the CpG-associated methylation levels of lncRNA LOC554202 decreased significantly, and in turn upregulated both miR-31 and its host gene LOC554202 in breast cancer cells. We also observed the significant inhibition of miR-31-targeted genes following GBK treatment, including RHOA, WAVE3, and SATB2, with functions closely related to cancer cell invasion, migration, and proliferation. Furthermore, we revealed that the combination of GBK and DDP had a synergistic effect on inhibiting the proliferation of breast cancer cells in vitro and in vivo, especially in triple negative breast cancer (TNBC).

Conclusions

This study investigated the target of GBK in the inhibition of breast cancer migration and invasion, and the underlying mechanisms involved, providing theoretical support for the development of GBK as an auxiliary drug for clinical treatment.

Lysophosphatidic acid suppresses apoptosis of high-grade serous ovarian cancer cells by inducing autophagy activity and promotes cell-cycle progression via EGFR-PI3K/Aurora-AThr288-geminin dual signaling pathways

Lysophosphatidic acid (LPA) and geminin are overexpressed in ovarian cancer, and increasing evidence supports their contribution to ovarian tumor development. Here, we reveal that geminin depletion induces autophagy suppression and enhances reactive oxygen species (ROS) production and apoptosis of high-grade serous ovarian cancer (HGSOC) cells. Bioinformatics analysis and pharmacological inhibition studies confirm that LPA activates geminin expression in the early S phase in HGSOC cells via the LPAR1/3/MMPs/EGFR/PI3K/mTOR pathway. Furthermore, LPA phosphorylates Aurora-A kinase on Thr288 through EGFR transactivation, and this event potentiates additional geminin stabilization. In turn, overexpressed and stabilized geminin regulates DNA replication, cell-cycle progression, and cell proliferation of HGSOC cells. Our data provide potential targets for enhancing the clinical benefit of HGSOC precision medicine.