Detailed in vitro studies on the effects of perfluorooctanoic acid (PFOA) have demonstrated that activation of peroxisome proliferator-activated receptor α (PPARα) is a key process by which PFOA ...affects the malignancy of estrogen receptor α (ERα)-positive breast cancer cells. However, there is very little information on the PPARα-regulated genes responsible for the effects of PFOA in ERα-negative breast cancer cell malignancy. We recently demonstrated that fatty acid 2-hydroxylase (FA2H) stimulates the migration of ERα-negative human MDA-MB-231 cells, and PPARα is a key factor for the induction of FA2H in these cells. However, evidence for the relationship between PFOA exposure and PPARα-FA2H axis-driven migration has not been obtained. Here we analyzed the effects of PFOA on PPARα transcription and FA2H expression in relation to MDA-MB-231 cell migration. We found that simultaneously with stimulated migration, PFOA upregulated FA2H and activated the transcription of PPARα. FA2H-selective siRNA, but not siRNA control, clearly dampened PFOA-mediated cell migration. There is an inhibitory interaction between PPARα and PPARβ/δ (i.e., PPARβ/δ can suppress PPARα-mediated transcription) in MDA-MB-231 cells, but even in the presence of PPARβ/δ expression, PFOA appeared to free PPARα to upregulate FA2H. Collectively, our findings show that i) PFOA activates PPARα-mediated transcription, ii) PFOA stimulates migration dependent on FA2H expression, and iii) mechanistically, PFOA relieves PPARβ/δ suppression of PPARα activity to upregulate FA2H in MDA-MB-231 cells.
Lung cancer and related diseases have been one of the most common causes of deaths worldwide. Genomic-based biomarkers may hardly reflect the underlying dynamic molecular mechanism of functional ...protein interactions, which is the center of a disease. Recent developments in mass spectrometry (MS) have made it possible to analyze disease-relevant proteins expressed in clinical specimens by proteomic challenges. Areas covered: To understand the molecular mechanisms of lung cancer and its subtypes, chronic obstructive pulmonary disease (COPD), asthma and others, great efforts have been taken to identify numerous relevant proteins by MS-based clinical proteomic approaches. Since lung cancer is a multifactorial disease that is biologically associated with asthma and COPD among various lung diseases, this study focused on proteomic studies on biomarker discovery using various clinical specimens for lung cancer, COPD, and asthma. Expert commentary: MS-based exploratory proteomics utilizing clinical specimens, which can incorporate both experimental and bioinformatic analysis of protein-protein interaction and also can adopt proteogenomic approaches, makes it possible to reveal molecular networks that are relevant to a disease subgroup and that could differentiate between drug responders and non-responders, good and poor prognoses, drug resistance, and so on.
No therapeutic targets have been identified for lung squamous cell cancer (SqCC) which is the second most prevalent lung cancer because its molecular profiles remain unclear. This study aimed to ...unveil disease-related protein networks by proteomic and bioinformatic assessment of laser-microdissected cancerous cells from seven SqCCs compared with eight representative lung adenocarcinomas. We identified three network modules significant to lung SqCC using weighted gene co-expression network analysis. One module was intrinsically annotated to keratinization and cell proliferation of SqCC, accompanied by hypoxia-induced aerobic glycolysis, in which key regulators were activated (HIF1A, ROCK2, EFNA1-5) and highly suppressed (KMT2D). The other two modules were significant for translational initiation, nonsense-mediated mRNA decay, inhibited cell death, and interestingly, eIF2 signaling, in which key regulators, MYC and MLXIPL, were highly activated. Another key regulator LARP1, the master regulator in cap-dependent translation, was highly suppressed although upregulations were observed for hub proteins including EIF3F and LARP1 targeted ribosomal proteins, among which PS25 is the key ribosomal protein in IRES-dependent translation. Our results suggest an underlying progression mechanism largely caused by switching to the cap-independent, IRES-dependent translation of mRNA subsets encoding oncogenic proteins. Our findings may help to develop therapeutic strategies to improve patient outcomes.
Targeted protein degradation by proteolysis-targeting chimera (PROTAC) is one of the exciting modalities for drug discovery and biological discovery. It is important to select an appropriate linker, ...an E3 ligase ligand, and a target protein ligand in the development; however, it is necessary to synthesize a large number of PROTACs through trial and error. Herein, using a docking simulation of the ternary complex of a hematopoietic prostaglandin D synthase (H-PGDS) degrader, H-PGDS, and cereblon, we have succeeded in developing PROTAC(H-PGDS)-7 (6), which showed potent and selective degradation activity (DC50 = 17.3 pM) and potent suppression of prostaglandin D2 production in KU812 cells. Additionally, in a Duchenne muscular dystrophy model using mdx mice with cardiac hypertrophy, compound 6 showed better inhibition of inflammatory cytokines than a potent H-PGDS inhibitor TFC-007. Thus, our results demonstrated that in silico simulation would be useful for the rational development of PROTACs.
Hepatocellular carcinoma develops in either chronically injured or seemingly intact livers. To explore the tumorigenic mechanisms underlying these different conditions, we compared the mRNA ...expression profiles of mouse hepatocellular tumors induced by the repeated injection of CCl4 or a single diethylnitrosamine (DEN) injection using a cDNA microarray. We identified tumor‐associated genes that were expressed differentially in the cirrhotic CCl4 model (H19, Igf2, Cbr3, and Krt20) and the non‐cirrhotic DEN model (Tff3, Akr1c18, Gpc3, Afp, and Abcd2) as well as genes that were expressed comparably in both models (Ly6d, Slpi, Spink3, Scd2, and Cpe). The levels and patterns of mRNA expression of these genes were validated by quantitative RT‐PCR analyses. Most of these genes were highly expressed in mouse livers during the fetal/neonatal periods. We also examined the mRNA expression of these genes in mouse tumors induced by thioacetamide, another cirrhotic inducer, and those that developed spontaneously in non‐cirrhotic livers and found that they shared a similar expression profile as that observed in CCl4‐induced and DEN‐induced tumors, respectively. There was a close relationship between the expression levels of Igf2 and H19 mRNA, which were activated in the cirrhotic models. Our results show that mouse liver tumors reactivate fetal/neonatal genes, some of which are specific to cirrhotic or non‐cirrhotic modes of pathogenesis.
We have identified 15 liver tumor‐associated genes in cirrhotic and noncirrhotic mouse liver tumor models. Most of these genes share an oncofetal nature and differentially activated in cirrhotic and noncirrhotic conditions. The activation of the Igf2 axis might be closely related to the liver tumors associated with chronic liver injury.
Activation of the phosphoinositide 3-kinase–AKT, Yes-associated protein (YAP), and MYC pathways is involved in human liver cancers, including hepatocellular carcinoma (HCC) and cholangiocarcinoma ...(CC). However, the nature of the interactions among these pathways has remained poorly understood. Herein, we demonstrate the coordination of these pathways during the formation of mouse liver tumors induced by hepatocyte-specific somatic integration of myristoylated AKT, mutant YAP, Myc, or their combinations. Although the introduction of YAP or Myc alone was inefficient in inducing tumors, these proteins accelerated tumorigenesis induced by AKT. The generated tumors demonstrated various histological features: low-grade HCC by AKT/Myc, CC by AKT/YAP, and high-grade HCC by AKT/Myc/YAP. CC induced by AKT/YAP was associated with activation of the Notch pathway. Interestingly, the combination of Myc and YAP generated tumors composed of hepatoblast/stem-like cells expressing mRNA for Afp, Dlk1, Nanog, and Sox2 and occasionally forming immature ducts. Finally, immunohistochemical analysis revealed that human HCC and CC were predominantly associated with phosphorylation of S6 and glycogen synthase kinase-3β, respectively, and >60% of CC cases were positive for both phosphorylated glycogen synthase kinase--3β and YAP. Our study suggests that hepatocyte-derived tumors demonstrate a wide spectrum of tumor phenotypes, including HCC, CC, and hepatoblastoma-like, through the combinatory effects of the oncogenic pathways and that the state of the phosphoinositide 3-kinase–AKT pathway is a key determinant of differentiation.
Small-cell lung carcinoma (SCLC) and large-cell neuroendocrine lung carcinoma (LCNEC) are high-grade lung neuroendocrine tumors (NET). However, comparative protein expression within SCLC and LCNEC ...remains unclear. Here, protein expression profiles were obtained via mass spectrometry-based proteomic analysis. Weighted gene co-expression network analysis (WGCNA) identified co-expressed modules and hub genes. Of 34 identified modules, six were significant and selected for protein-protein interaction (PPI) network analysis and pathway enrichment. Within the six modules, the activation of cellular processes and complexes, such as alternative mRNA splicing, translation initiation, nucleosome remodeling and deacetylase (NuRD) complex, SWItch/Sucrose Non-Fermentable (SWI/SNF) superfamily-type complex, chromatin remodeling pathway, and mRNA metabolic processes, were significant to SCLC. Modules enriched in processes, including signal recognition particle (SRP)-dependent co-translational protein targeting to membrane, nuclear-transcribed mRNA catabolic process of nonsense-mediated decay (NMD), and cellular macromolecule catabolic process, were characteristically activated in LCNEC. Novel high-degree hub genes were identified for each module. Master and upstream regulators were predicted via causal network analysis. This study provides an understanding of the molecular differences in tumorigenesis and malignancy between SCLC and LCNEC and may help identify potential therapeutic targets.
The tumourigenesis of early lung adenocarcinomas, including adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA), and lepidic predominant invasive adenocarcinoma (LPA), remains ...unclear. This study aimed to capture disease-related molecular networks characterising each subtype and tumorigenesis by assessing 14 lung adenocarcinomas (AIS, five; MIA, five; LPA, four). Protein-protein interaction networks significant to the three subtypes were elucidated by weighted gene co-expression network analysis and pairwise G-statistics based analysis. Pathway enrichment analysis for AIS involved extracellular matrix proteoglycans and neutrophil degranulation pathway relating to tumour growth and angiogenesis. Whereas no direct networks were found for MIA, proteins significant to MIA were involved in oncogenic transformation, epithelial-mesenchymal transition, and detoxification in the lung. LPA was associated with pathways of HSF1-mediated heat shock response regulation, DNA damage repair, cell cycle regulation, and mitosis. Genomic alteration analysis suggested that LPA had both somatic mutations with loss of function and copy number gains more frequent than MIA. Oncogenic drivers were detected in both MIA and LPA, and also LPA had a higher degree of copy number loss than MIA. Our findings may help identifying potential therapeutic targets and developing therapeutic strategies to improve patient outcomes.
Background and Aims
Mitogen‐activated protein kinase kinase (MKK) 7 and MKK4 are upstream activators of c‐Jun NH2‐terminal kinases (JNKs) and have been shown to be required for the early development ...of the liver. Although it has been suggested that MKK7 might be involved in the regulation of hepatocyte proliferation, the functional role of MKK7 in the liver has remained unclear.
Approach and Results
Here, we examined phenotypic alterations in liver‐specific or hepatocyte/hematopoietic cell–specific MKK7 knockout (KO) mice, which were generated by crossing MKK7LoxP/LoxP with albumin–cyclization recombination (Alb‐Cre) or myxovirus resistance protein 1–Cre mice, respectively. The livers of Alb‐Cre−/+ MKK7LoxP/LoxP mice developed without discernible tissue disorganization. MKK7 KO mice responded normally to liver injuries incurred by partial hepatectomy or injection of CCl4. However, tissue repair following CCl4‐induced injury was delayed in MKK7 KO mice compared with that of control mice. Furthermore, after repeated injections of CCl4 for 8 weeks, the liver in MKK7 KO mice showed intense fibrosis with increased protractive hepatocyte proliferation, suggesting that MKK7 deficiency might affect regenerative responses of hepatocytes in the altered tissue microenvironment. MKK7 KO hepatocytes demonstrated normal proliferative activity when cultured in monolayers. However, MKK7 KO significantly suppressed branching morphogenesis of hepatocyte aggregates within a collagen gel matrix. Microarray analyses revealed that suppression of branching morphogenesis in MKK7 KO hepatocytes was associated with a reduction in mRNA expression of transgelin, glioma pathogenesis related 2, and plasminogen activator urokinase‐type (Plau); and forced expression of these genes in MKK7 KO hepatocytes partially recovered the attenuated morphogenesis. Furthermore, hepatocyte‐specific overexpression of Plau rescued the impaired tissue repair of MKK7 KO mice following CCl4‐induced injury.
Conclusions
MKK7 is dispensable for the regenerative proliferation of hepatocytes but plays important roles in repair processes following parenchymal destruction, possibly through modulation of hepatocyte–extracellular matrix interactions.
Although hematopoietic prostaglandin D synthase (H-PGDS) is an attractive target for treatment of a variety of diseases, including allergic diseases and Duchenne muscular dystrophy, no H-PGDS ...inhibitors have yet been approved for treatment of these diseases. Therefore, the development of novel agents having other modes of action to modulate the activity of H-PGDS is required. In this study, a chimeric small molecule that degrades H-PGDS via the ubiquitin-proteasome system, PROTAC(H-PGDS)-1, was developed. PROTAC(H-PGDS)-1 is composed of two ligands, TFC-007 (that binds to H-PGDS) and pomalidomide (that binds to cereblon). PROTAC(H-PGDS)-1 showed potent activity in the degradation of H-PGDS protein via the ubiquitin-proteasome system and in the suppression of prostaglandin D2 (PGD2) production. Notably, PROTAC(H-PGDS)-1 showed sustained suppression of PGD2 production after the drug removal, whereas PGD2 production recovered following removal of TFC-007. Thus, the H-PGDS degraderPROTAC(H-PGDS)-1is expected to be useful in biological research and clinical therapies.
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