Decoding the full picture of Raf1 function based on its interacting proteins

SODD Promotes Lung Cancer Tumorigenesis by Activating the PDK1/AKT and RAF/MEK/ERK Signaling

Background: The Bcl2-associated athanogene4 (BAG4/SODD) protein could be identified as a tumor marker for several malignancies and plays a major role in the occurrence, development, and drug resistance of tumors. However, the role of Silencer of death domains (SODD) in lung carcinogenesis is still elusive. Objective: To illuminate the effect of SODD on the proliferation, migration, invasion, and apoptosis of lung cancer cells and tumor growth in vivo and explore the corresponding mechanism. Methods: The expression of SODD in tumor and normal tissues was determined and compared via western blot. SODD gene knockout lung cancer cells (H1299 cells) were established through a CRISPR/Cas9 gene deleting system, and a transient SODD overexpression of H1299 cells was also constructed. Then, cell proliferation and invasion were assessed through colony formation and cell counting kit-8 assays, transwell migration assays, and wound healing assays. Cell drug sensitivity is also analyzed by Cell Counting Kit-8 assay. The flow cytometer was used to perform cell circle and apoptosis analysis. The interaction of SODD and RAF-1 was confirmed by co-immunoprecipitation, and the phosphorylated level of Phosphatidylinositol 3-kinase (PI3K), Serine/threonine-protein kinase (AKT), Rapidly accelerated fibrosarcoma (RAF)-1,and extracellular signal regulated kinase (ERK) in cells was examined by western blot to evaluate the activation of PI3K/PDK1/AKT and RAF/MEK/ERK pathways. In vivo, Xenograft tumor assay of SODD knockout H1299 cells was used to evaluate further the role of SODD on the proliferation of H1299 cells. Results: SODD binds to RAF-1 and is over-expressed in lung tissues, and promotes the proliferation, migration, invasion, and drug sensitivity of H1299 cells. The reduced cells in the S phase and increased cells arrested in the G2/M phase were found in SODD knockout H1299 cells, and more cells got apoptosis. The expression of 3-phosphoinositide-dependent protein kinase 1(PDK1) protein in SODD knockout H1299 cells decreases distinctively, and the phosphorylated level of AKT, RAF-1, and ERK-1 kinase in SODD knockout H1299 cells is also less than that in normal H1299 cells. In contrast, SODD overexpression significantly increases the phosphorylation of AKT. In vivo, SODD promotes the tumorigenicity of H1299 cells in nude mice. Conclusions: SODD is overexpressed in lung tissues and plays a considerable role in the development and progression of lung cancer by regulating the PI3K/PDK1/AKT and RAF/MEK/ERK pathways.

YWHAE-NUTM2 oncoprotein regulates proliferation and cyclin D1 via RAF/MAPK and Hippo pathways

Endometrial stromal sarcoma (ESS) is the second most common subtype of uterine mesenchymal cancer, after leiomyosarcoma, and oncogenic fusion proteins are found in many ESS. Our previous studies demonstrated transforming properties and diagnostic relevance of the fusion oncoprotein YWHAE–NUTM2 in high-grade endometrial stromal sarcoma (HG-ESS) and showed that cyclin D1 is a diagnostic biomarker in these HG-ESS. However, YWHAE–NUTM2 mechanisms of oncogenesis and roles in cyclin D1 expression have not been characterized. In the current studies, we show YWHAE-NUTM2 complexes with both BRAF/RAF1 and YAP/TAZ in HG-ESS. These interactions are functionally relevant because YWHAE-NUTM2 knockdown in HG-ESS and other models inhibits RAF/MEK/MAPK phosphorylation, cyclin D1 expression, and cell proliferation. Further, cyclin D1 knockdown in HG-ESS dephosphorylates RB1 and inhibits proliferation. In keeping with these findings, we show that MEK and CDK4/6 inhibitors have anti-proliferative effects in HG-ESS, and combinations of these inhibitors have synergistic activity. These findings establish that YWHAE-NUTM2 regulates cyclin D1 expression and cell proliferation by dysregulating RAF/MEK/MAPK and Hippo/YAP-TAZ signaling pathways. Recent studies demonstrate Hippo/YAP-TAZ pathway aberrations in many sarcomas, but this is among the first studies to demonstrate a well-defined oncogenic mechanism as the cause of Hippo pathway dysregulation.

Specific Antiproliferative Properties of Proteinaceous Toxin Secretions from the Marine Annelid Eulalia sp. onto Ovarian Cancer Cells

As Yondelis joins the ranks of approved anti-cancer drugs, the benefit from exploring the oceans' biodiversity becomes clear. From marine toxins, relevant bioproducts can be obtained due to their potential to interfere with specific pathways. We explored the cytotoxicity of toxin-bearing secretions of the polychaete Eulalia onto a battery of normal and cancer human cell lines and discovered that the cocktail of proteins is more toxic towards an ovarian cancer cell line (A2780). The secretions' main proteins were identified by proteomics and transcriptomics: 14-3-3 protein, Hsp70, Rab3, Arylsulfatase B and serine protease, the latter two being known toxins. This mixture of toxins induces cell-cycle arrest at G2/M phase after 3h exposure in A2780 cells and extrinsic programmed cell death. These findings indicate that partial re-activation of the G2/M checkpoint, which is inactivated in many cancer cells, can be partly reversed by the toxic mixture. Protein-protein interaction networks partake in two cytotoxic effects: cell-cycle arrest with a link to RAB3C and RAF1; and lytic activity of arylsulfatases. The discovery of both mechanisms indicates that venomous mixtures may affect proliferating cells in a specific manner, highlighting the cocktails' potential in the fine-tuning of anti-cancer therapeutics targeting cell cycle and protein homeostasis.

Small molecule inhibitor agerafenib effectively suppresses neuroblastoma tumor growth in mouse models via inhibiting ERK MAPK signaling

Neuroblastoma (NB) is the most common extracranial solid tumor in early childhood. Despite intensive multimodal therapy, nearly half of children with high-risk disease will relapse with therapy-resistant tumors. Dysregulation of MAPK pathway has been implicated in the pathogenesis of relapsed and refractory NB patients, which underscores the possibility of targeting MAPK signaling cascade as a novel therapeutic strategy. In this study, we found that high expressions of RAF family kinases correlated with advanced tumor stage, high-risk disease, tumor progression, and poor overall survival. Targeted inhibition of RAF family kinases with the novel small molecule inhibitor agerafenib abrogated the activation of ERK MAPK pathway in NB cells. Agerafenib significantly inhibited the cell proliferation and colony formation ability of NB cells in vitro, and its combination with traditional chemotherapy showed a synergistic pro-apoptotic effect. More importantly, agerafenib exhibited a favorable toxicity profile, potently suppressed tumor growth, and prolonged survival in NB mouse models. In conclusion, our preclinical data suggest that agerafenib might be an effective therapeutic agent for NB treatment, both as a single-agent and in combination with chemotherapy.