Dynamic quantitative proteomics characterization of TNF-α-induced necroptosis

MEST promotes lung cancer invasion and metastasis by interacting with VCP to activate NF-κB signaling

Background

Cell invasion is a hallmark of metastatic cancer, leading to unfavorable clinical outcomes. In this study, we established two highly invasive lung cancer cell models (A549-i8 and H1299-i8) and identified mesoderm-specific transcript (MEST) as a novel invasive regulator of lung cancer. We aim to characterize its biological function and clinical significance in lung cancer metastasis.

Methods

Transwell invasion assay was performed to establish high-invasive lung cancer cell model. Immunohistochemistry (IHC) was used to detect MEST expression in tumor tissues. Mass spectrometry and bioinformatic analyses were used to identify MEST-regulated proteins and binding partners. Co-immunoprecipitation assay was performed to detect the interaction of MEST and VCP. The biological functions of MEST were investigated in vitro and in vivo. Immunofluorescence staining was conducted to explore the colocalization of MEST and VCP.

Results

MEST overexpression promoted metastasis of lung cancer cells in vivo and in vitro by activating NF-κB signaling. MEST increased the interaction between VCP and IκBα, which accelerated IκBα degradation and NF-κB activation. Such acceleration was abrogated by VCP silencing, indicating that MEST is an upstream activator of the VCP/IκBα/NF-κB signaling pathway. Furthermore, high expressions of MEST and VCP were associated with poor survival of lung cancer patients.

Conclusion

Collectively, these results demonstrate that MEST plays an important role in driving invasion and metastasis of lung cancer by interacting with VCP to coordinate the IκBα/NF-κB pathway. Targeting the MEST/VCP/IκBα/NF-κB signaling pathway may be a promising strategy to treat lung cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02107-1.

Quantitative Mitochondrial Proteomics Reveals ANXA7 as a Crucial Factor in Mitophagy

Mitochondria are involved in many crucial cellular processes. Maintaining healthy mitochondria is essential for cellular homeostasis. Parkin-dependent mitophagy plays an important role in selectively eliminating damaged mitochondria in mammalian cells. However, mechanisms of Parkin-dependent mitophagy remain elusive. In this research, we performed data-independent acquisition-based quantitative mitochondrial proteomics to study the proteomic alterations of carbonyl cyanide m-chlorophenylhydrazone (CCCP)-induced Parkin-mediated mitophagy. We identified 222 differentially expressed proteins, with 76 upregulations and 146 downregulations, which were potentially involved in mitophagy. We then demonstrated that annexin A7 (ANXA7), a calcium-dependent phospholipid-binding protein, can translocate to impaired mitochondria upon CCCP treatment, where it played a pivotal part in the process of Parkin-dependent mitophagy via interacting with BASP1. As a mitochondrial uncoupling agent, CCCP indirectly regulated ANXA7 and BASP1 to induce Parkin-dependent mitophagy.

Dissecting primate early post-implantation development using long-term in vitro embryo culture

The transition from peri-implantation to gastrulation in mammals entails the specification and organization of the lineage progenitors into a body plan. Technical and ethical challenges have limited understanding of the cellular and molecular mechanisms that underlie this transition. We established a culture system that enabled the development of cynomolgus monkey embryos in vitro for up to 20 days. Cultured embryos underwent key primate developmental stages, including lineage segregation, bilaminar disc formation, amniotic and yolk sac cavitation, and primordial germ cell–like cell (PGCLC) differentiation. Single-cell RNA-sequencing analysis revealed development trajectories of primitive endoderm, trophectoderm, epiblast lineages, and PGCLCs. Analysis of single-cell chromatin accessibility identified transcription factors specifying each cell type. Our results reveal critical developmental events and complex molecular mechanisms underlying nonhuman primate embryogenesis in the early postimplantation period, with possible relevance to human development.

Liensinine perchlorate inhibits colorectal cancer tumorigenesis by inducing mitochondrial dysfunction and apoptosis

SCOPE

Colorectal cancer (CRC) is one of the most common cancers worldwide with poor survival and limited therapeutic options, and there is an urgent need to develop novel therapeutic agents with good treatment efficiency and low toxicity. This study aims to examine the anticancer bioactivity of liensinine, a constituent of Nelumbo nucifera Gaertn, in CRC and investigate the action mechanisms involved.

METHODS AND RESULTS

Liensinine was found to induce apoptosis and exert a significant inhibitory effect on the proliferation and colony-forming ability of CRC cells in a dose-dependent manner without any observed cytotoxicity on normal colorectal epithelial cells. Mechanistically, our data from quantitative proteomics, western blot analysis and flow cytometry analyses demonstrated that exposure of CRC cells to liensinine caused cell cycle arrest, mitochondrial dysfunction and apoptosis, accompanied by the activation of the JNK signaling pathway. Furthermore, animal experiments showed that liensinine markedly suppressed the growth of CRC tumor xenografts in nude mice by reducing the Ki-67 proliferation index, but did not damage the vital organs of the animals.

CONCLUSION

This study demonstrated for the first time that liensinine, a food-source natural product, could be a novel therapeutic strategy for treating CRC without obvious side effects.

Comparative Proteomics Analysis Identifies Cdc42-Cdc42BPA Signaling as Prognostic Biomarker and Therapeutic Target for Colon Cancer Invasion

Metastasis is one of the major causes of treatment failure in the patients with colon cancer. The aim of our study is to find key proteins and pathways that drive invasion and metastasis in colon cancer. Eight rounds of selection of cancer cells invading through matrigel-coated chamber were performed to obtain highly invasive colon cancer sublines HCT116-I8 and RKO-I8. Stable Isotope Labeling by Amino Acids in Cell Culture technology was used to identify the differently expressed proteins, and the proteomics data were analyzed by ingenuity pathway analysis. PAK1-PBD immunoprecipitation combined with Western blot were carried out to determine Cdc42 activity, and qRT-PCR and Western blot were used to determine gene expression. The functional role of Cdc42BPA and Cdc42 pathway in colon cancer invasion was studied by loss-of-function experiments including pharmacological blockade, siRNA knockdown, chamber invasion, and WST-1 assays. Human colon cancer tissue microarray was analyzed by immunohistochemistry for overexpression of Cdc42BPA and its correlation with clinicopathological parameters and patient survival outcomes. HCT116-I8 and RKO-I8 cells showed significantly stronger invasive potential as well as decreased E-cadherin and increased vimentin expressions compared with parental cells. The differently expressed proteins in I8 cells compared with parental cells were identified. Bioinformatics analysis of proteomics data suggested that Cdc42BPA protein and Cdc42 signaling pathway are important for colon cancer invasion, which was confirmed by experimental data showing upregulation of Cdc42BPA and higher expression of active GTP-bound form of Cdc42 in HCT116-I8 and RKO-I8 cells. Functionally, pharmacological and genetic blockade of Cdc42BPA and Cdc42 signaling markedly suppressed colon cancer cell invasion and reversed epithelial mesenchymal transition process. Furthermore, compared with adjacent normal tissues, Cdc42BPA expression was significantly higher in colon cancer tissues and further upregulated in metastatic tumors in lymph nodes. More importantly, Cdc42BPA expression was correlated with metastasis and poor survival of the patients with colon cancer. This study provides the first evidence that Cdc42BPA and Cdc42 signaling are important for colon cancer invasion, and Cdc42BPA has potential implications for colon cancer prognosis and treatment.

KCTD12 promotes tumorigenesis by facilitating CDC25B/CDK1/Aurora A-dependent G2/M transition

Cell cycle dysregulation leads to uncontrolled cell proliferation and tumorigenesis. Understanding the molecular mechanisms underlying cell cycle progression can provide clues leading to the identification of key proteins involved in cancer development. In this study, we performed proteomics analysis to identify novel regulators of the cell cycle. We found that potassium channel tetramerization domain containing 12 (KCTD12) was significantly upregulated in M phase compared with S phase. We also found that KCTD12 overexpression not only facilitated the G2/M transition and induced cancer cell proliferation, but also promoted the growth of subcutaneous tumors and Ki-67 proliferation index in mice. Regarding the mechanism underlying these phenomena, cyclin-dependent kinase 1 (CDK1) was identified as an interacting partner of KCTD12 by immunoprecipitation and mass spectrometry analysis, which showed that KCTD12 activated CDK1 and Aurora kinase A (Aurora A) and that the effects of KCTD12 on CDK1 phosphorylation and cell proliferation were abrogated by cell division cycle 25B (CDC25B) silencing. In addition, Aurora A phosphorylated KCTD12 at serine 243, thereby initiating a positive feedback loop necessary for KCTD12 to exert its cancer-promoting effects. Furthermore, we analyzed the expression levels of various genes and the correlations between the expression of these genes and survival using tumor tissue microarray and Gene Expression Omnibus (GEO) data sets. The data showed that KCTD12 expression was significantly upregulated in cervical and lung cancers. More importantly, high KCTD12 expression was associated with larger tumor sizes, higher pathological stages and poor patient survival. Collectively, our study demonstrate that KCTD12 binds to CDC25B and activates CDK1 and Aurora A to facilitate the G2/M transition and promote tumorigenesis and that Aurora A phosphorylates KCTD12 at serine 243 to trigger a positive feedback loop, thereby potentiating the effects of KCTD12. Thus, the KCTD12-CDC25B-CDK1-Aurora A axis has important implications for cancer diagnoses and prognoses.

Jolkinolide B induces apoptosis of colorectal carcinoma through ROS-ER stress-Ca2+-mitochondria dependent pathway

Colorectal carcinoma (CRC) remains one of the leading causes of death in cancer-related diseases. In this study, we aimed to investigate the anticancer effect of Jolkinolide B (JB), a bioactive diterpenoid component isolated from the dried roots of Euphorbia fischeriana Steud, on CRC cells and its underlying mechanisms. We found that JB suppressed the cell viability and colony formation of CRC cells, HT29 and SW620. Annexin V/PI assay revealed that JB induced apoptosis in CRC cells, which was further confirmed by the increased expression of cleaved-caspase3 and cleaved-PARP. iTRAQ-based quantitative proteomics was performed to identify JB-regulated proteins in CRC cells. Gene Ontology (GO) analysis revealed that these JB-regulated proteins were mainly involved in ER stress response, which was evidenced by the expression of ER stress marker proteins, HSP90, Bip and PDI. Moreover, we found that JB provoked the generation of reactive oxygen species (ROS), and that inhibition of the ROS generation with N-acetyl L-cysteine could reverse the JB-induced apoptosis. Confocal microscopy and flow cytometry showed that JB treatment enhanced intracellular and mitochondrial Ca²⁺ level and JC-1 assay revealed a loss of mitochondrial membrane potential in CRC after JB treatment. The mitochondrial Ca²⁺ uptake and depolarization can be blocked by Ruthenium Red (RuRed), an inhibitor of mitochondrial Ca²⁺ uniporter. Taken together, we demonstrated that JB exerts its anticancer effect by ER stress-Ca²⁺-mitochondria signaling, suggesting the promising chemotherapeutic potential of JB for the treatment of CRC.

Inhibition of Nrf2 enhances the anticancer effect of 6-O-angeloylenolin in lung adenocarcinoma

6-O-Angeloylenolin (6-OA), a sesquiterpene lactone isolated from Centipeda minima (L.) A. Br. (Compositae), has been used to treat respiratory diseases for centuries. However, whether and how 6-OA exerts anticancer effects against lung cancer remains to be elucidated. In this study, we showed that 6-OA markedly suppressed the cell viability and colony formation of lung cancer cells H1299 and A549, with no significant toxic effect on non-cancer cells HBE. Annexin V/7-AAD assay revealed that 6-OA induced cell apoptosis in dose- and time-dependent manners, which was further confirmed by the increased expression of cleaved caspase-3. To uncover the molecular mechanism how 6-OA exerts its anticancer effects, SILAC quantitative proteomics was performed to identify 6-OA-regulated proteins in lung cancer cells. Ingenuity Pathway Analysis revealed that these 6-OA-regulated proteins were mainly involved in Nrf2-mediated oxidative stress response, which was confirmed by the nuclear translocation of Nrf2 upon 6-OA treatment. Moreover, we found that 6-OA stimulated the accumulation of reactive oxygen species (ROS), whereas inhibition of ROS generation with N-acetyl l-cysteine could block the 6-OA-induced anticancer effects. Furthermore, blockade of cellular anti-oxidative system by Nrf2 knockdown significantly augmented the 6-OA-induced apoptosis. Taken together, we demonstrated that 6-OA exerts its anticancer effects by generating ROS, and inhibition of Nrf2 anti-oxidative system potentiated these effects. These results suggest that 6-OA may be used to treat lung cancer, with better outcome by combining with Nrf2 inhibitor to block Nrf2 pathway.

LRRK2 and the "LRRKtosome" at the Crossroads of Programmed Cell Death: Clues from RIP Kinase Relatives

Since its cloning and identification in 2004, considerable gains have been made in the understanding of the basic functionality of leucine-rich repeat kinase 2 (LRRK2), including its kinase and GTPase activities, its protein interactors and subcellular localization, and its expression in the CNS and peripheral tissues. However, the mechanism(s) by which expression of mutant forms of LRRK2 lead to the death of dopaminergic neurons of the ventral midbrain remains largely uncharacterized. Because of its complex domain structure, LRRK2 exhibits similarities with multiple protein families including ROCO proteins, as well as the RIP kinases. Cellular models in which mutant LRRK2 is overexpressed in neuronal-like cell lines or in primary neurons have found evidence of apoptotic cell death involving components of the extrinsic as well as intrinsic death pathways. However, since the expression of LRRK2 is comparatively quite low in ventral midbrain dopaminergic neurons, the possibility exists that non-cell autonomous signaling also contributes to the loss of these neurons. In this chapter, we will discuss the different neuronal death pathways that may be activated by mutant forms of LRRK2, guided in part by the behavior of other members of the RIP kinase protein family.