Whole-exome sequencing identified novel variants in three Chinese Leigh syndrome pedigrees.

Leigh syndrome (LS), the most common mitochondrial disease in early childhood, usually manifests variable neurodegenerative symptoms and typical brain magnetic resonance imaging (MRI) lesions. To date, pathogenic variants in more than 80 genes have been identified. However, there are still many cases without molecular diagnoses, and thus more disease-causing variants need to be unveiled. Here, we presented three clinically suspected LS patients manifesting neurological symptoms including developmental delay, hypotonia, and epilepsy during the first year of age, along with symmetric brain lesions on MRI. We explored disease-associated variants in patients and their nonconsanguineous parents by whole-exome sequencing and subsequent Sanger sequencing verification. Sequencing data revealed three pairs of disease-associated compound heterozygous variants: c.1A>G (p.Met1?) and 409G>C (p.Asp137His) in SDHA, c.1253G>A (p.Arg418His) and 1300C>T (p.Leu434Phe) in NARS2, and c.5C>T (p.Ala2Val) and 773T>G (p.Leu258Trp) in ECHS1. Among them, the likely pathogenic variants c.409G>C (p.Asp137His) in SDHA, c.1300C>T (p.Leu434Phe) in NARS2, and c.773T>G (p.Leu258Trp) in ECHS1 were newly identified. Segregation analysis indicated the possible disease-causing nature of the novel variants. In silico prediction and three-dimensional protein modeling further suggested the potential pathogenicity of these variants. Our discovery of novel variants expands the gene variant spectrum of LS and provides novel evidence for genetic counseling.

Targeting tumor-associated macrophages: A potential treatment for solid tumors.

Tumor-associated macrophages (TAMs) in solid tumors exert protumor activities by releasing cytokines or growth factors into the tumor microenvironment. Increasing studies have also shown that TAMs play a key role in tumor progression, such as tumor angiogenesis, immunosuppression, cell proliferation, migration, invasion, and metastasis. A large body of evidence shows that the abundance of TAMs in solid tumors is correlated with poor disease prognosis and resistance to therapies. Therefore, targeting TAMs in solid tumors is considered to be a promising immunotherapeutic strategy. At present, the therapeutic strategies of targeting macrophages mainly include limiting monocyte recruitment, depletion strategies, promoting macrophage phagocytic activity, and induction of macrophage reprogramming. Additionally, targeting TAMs in combination with conventional therapies has been demonstrated to be a promising therapeutic strategy in solid tumors. In the present review, we summarized various TAMs-targeting therapeutic strategies for treating solid tumors. This review also discusses the challenges for targeting TAMs as tumor treatments, the obstacles in clinical trials, and the perspective for the future development of TAMs-targeting therapies for various cancers.

Macrophages confer resistance to BET inhibition in triple-negative breast cancer by upregulating IKBKE.

BET inhibitors (BETi) exhibit a strong anti-tumor activity in triple-negative breast cancer (TNBC). However, BETi resistance has been reported in TNBC. The mechanisms of resistance have not been demonstrated. Tumor-associated macrophages (TAMs) are frequently involved in cancer cells resistance to chemotherapy, also associated with poor prognosis in TNBC. However, the role of TAMs in BETi resistance remains unknown. Here, we found that BETi JQ1 and I-BET151 exerted anti-tumor effects in TNBC by decreasing IKBKE expression to attenuate NF-κB signaling. TAMs have been reported to associate with chemoresistance in breast cancer. Here, we firstly found that TNBC-stimulated TAMs activated NF-κB signaling by upregulating IKBKE expression to enhance breast cancer cells resistance to BETi. The IKBKE levels were also proved to be higher in clinical TNBC tissues than Non-TNBC tissues, suggesting feedback induction of IKBKE expression by TNBC-stimulated TAMs in TNBC. Moreover, the induction of IKBKE by TAMs in TNBC cells was identified to be associated with STAT3 signaling, which was activated by TAM-secreted IL-6 and IL-10. Lastly, the combination of inhibitors of BET and STAT3 exerted a synergistic inhibition effects in TAM-cocultured or TAM CM-treated TNBC cells in vitro and in vivo. Altogether, our findings illustrated TNBC-activated macrophages conferred TNBC cells resistance to BETi via IL-6 or IL-10/STAT3/IKBKE/NF-κB axis. Blockade of IKBKE or double inhibition of BET and STAT3 might be a novel strategy for treatment of TNBC.

microRNA-499a promotes the progression and chemoresistance of cervical cancer cells by targeting SOX6.

Emerging evidence has indicated that microRNAs are involved in multiple processes of cancer development. Previous studies have demonstrated that microRNA-499a (miR-499a) plays both oncogenic and tumor suppressive roles in several types of malignancies, and genetic variants in miR-499a are associated with the risk of cervical cancer. However, the biological roles of miR-499a in cervical cancer have not been investigated. Quantitative real-time PCR was used to assess miR-499a expression in cervical cancer cells. Mimics or inhibitor of miR-499a was transfected into cervical cancer cells to upregulate or downregulate miR-499a expression. The effects of miR-499a expression change on cervical cancer cells proliferation, colony formation, tumorigenesis, chemosensitivity, transwell migration and invasion were assessed. The potential targets of miR-499a were predicted using online database tools and validated using real-time PCR, Western blot and luciferase reporter experiments. miR-499a was significantly upregulated in cervical cancer cells. Moreover, overexpression of miR-499a significantly enhanced the proliferation, cell cycle progression, colony formation, apoptosis resistance, migration and invasion of cervical cancer cells, while inhibiting miR-499a showed the opposite effects. Further exploration demonstrated that Sex-determining region Y box 6 was the direct target of miR-499a. miR-499a-induced SOX6 downregulation mediated the oncogenic effects of miR-499a in cervical cancer. Inhibiting miR-499a could enhance the anticancer effects of cisplatin in the xenograft mouse model of cervical cancer. Our findings for the first time suggest that miRNA-499a may play an important role in the development of cervical cancer and could serve as a potential therapeutic target.

Tumor-associated macrophages: an accomplice in solid tumor progression.

In many solid tumor types, tumor-associated macrophages (TAMs) are important components of the tumor microenvironment (TME). Moreover, TAMs infiltration is strongly associated with poor survival in solid tumor patients. In this review, we describe the origins of TAMs and their polarization state dictated by the TME. We also specifically focus on the role of TAMs in promoting tumor growth, enhancing cancer cells resistance to chemotherapy and radiotherapy, promoting tumor angiogenesis, inducing tumor migration and invasion and metastasis, activating immunosuppression. In addition, we discuss TAMs can be used as therapeutic targets of solid tumor in clinics. The therapeutic strategies include clearing macrophages and inhibiting the activation of TAMs, promoting macrophage phagocytic activity, limiting monocyte recruitment and other targeted TAMs therapies.

Dihydroartemisinin-induced unfolded protein response feedback attenuates ferroptosis via PERK/ATF4/HSPA5 pathway in glioma cells.

BACKGROUND: Dihydroartemisinin (DHA) has been shown to exert anticancer activity through iron-dependent reactive oxygen species (ROS) generation, which is similar to ferroptosis, a novel form of cell death. However, whether DHA causes ferroptosis in glioma cells and the potential regulatory mechanisms remain unclear. METHODS: Effects of DHA on the proliferation, cell death, ROS and lipid ROS generation as well as reduced gluthione consumption were assessed in glioma cells with or without ferroptosis inhibitor. The biological mechanisms by which glioma cells attenuate the pro-ferroptotic effects of DHA were assessed using molecular methods. RESULTS: DHA induced ferroptosis in glioma cells, as characterized by iron-dependent cell death accompanied with ROS generation and lipid peroxidation. However, DHA treatment simultaneously activated a feedback pathway of ferroptosis by increasing the expression of heat shock protein family A (Hsp70) member 5 (HSPA5). Mechanistically, DHA caused endoplasmic reticulum (ER) stress in glioma cells, which resulted in the induction of HSPA5 expression by protein kinase R-like ER kinase (PERK)-upregulated activating transcription factor 4 (ATF4). Subsequent HSPA5 upregulation increased the expression and activity of glutathione peroxidase 4 (GPX4), which neutralized DHA-induced lipid peroxidation and thus protected glioma cells from ferroptosis. Inhibition of the PERK-ATF4-HSPA5-GPX4 pathway using siRNA or small molecules increased DHA sensitivity of glioma cells by increasing ferroptosis both in vitro and in vivo. CONCLUSIONS: Collectively, these data suggested that ferroptosis might be a novel anticancer mechanism of DHA in glioma and HSPA5 may serve as a negative regulator of DHA-induced ferroptosis. Therefore, inhibiting the negative feedback pathway would be a promising therapeutic strategy to strengthen the anti-glioma activity of DHA.

Functional polymorphisms in circadian positive feedback loop genes predict postsurgical prognosis of gastric cancer.

BACKGROUND: Circadian positive feedback loop (CPFL) genes (CLOCK, BAML1, and NPAS2) have been implicated in cancer initiation and progression. The purpose of this study was to explore the effects of single-nucleotide polymorphisms (SNPs) in CPFL genes on prognosis of gastric cancer (GC) patients. METHODS: Nine functional SNPs from the three CPFL genes were genotyped in a cohort of 704 GC patients undergoing resection. Multivariate Cox regression model and Kaplan-Meier curve were used for prognosis analysis. RESULTS: Among the nine SNPs, rs11133399 in CLOCK, rs1044432 and rs2279284 in BAML1 were significantly associated with GC overall survival and recurrence-free survival. The unfavorable genotypes of these SNPs showed a cumulative effect on GC prognosis. Multivariate assessment model indicated that these SNPs, in conjunction with clinical variables, enhanced the power to predict GC prognosis. In addition, survival tree analysis revealed the genotype of rs11133399 as a primary risk factor contributing to the prognosis of GC patients. Functional assays showed that the G allele in rs11133399 significantly enhanced luciferase reporter activity than A allele. Immunohistochemical analysis further demonstrated that the genotype of rs11133399 was significantly associated with the expression level of CLOCK in GC tissues, suggesting that this SNP might affect the prognosis of GC through its influence on the expression of CLOCK gene. CONCLUSIONS: Our data indicate that SNPs in CPFL genes might contribute to the clinical outcome of GC through their impact on gene expression. Further studies are needed to elucidate its underlying molecular mechanisms.