Donghui Han

The increasing understanding of ferroptosis has indicated its role and therapeutic potential in cancer; however, this knowledge has yet to be translated into effective therapies. Glioblastoma (GBM) patients face a bleak prognosis and encounter challenges due to the limited treatment options available. In this study, we conducted a genome-wide CRISPR-Cas9 screening in the presence of a ferroptosis inducer (RSL3) to identify the key driver genes involved in ferroptosis. We identified ALOX15, a key lipoxygenase (LOX), as an essential driver of ferroptosis. Small activating RNA (saRNA) was used to mediate the expression of ALOX15 promoted ferroptosis in GBM cells. We then coated saALOX15-loaded mesoporous polydopamine (MPDA) with Angiopep-2-modified macrophage membranes (MMs) to reduce the clearance by the mononuclear phagocyte system (MPS) and increase the ability of the complex to cross the blood-brain barrier (BBB) during specific targeted therapy of orthotopic GBM. These generated hybrid nanoparticles (NPs) induced ferroptosis by mediating mitochondrial dysfunction and rendering mitochondrial morphology abnormal. In vivo, the modified MM enabled the NPs to target GBM cells, exert a marked inhibitory effect on GBM progression, and promote GBM radiosensitivity. Our results reveal ALOX15 to be a promising therapeutic target in GBM and suggest a biomimetic strategy that depends on the biological properties of MMs to enhance the in vivo performance of NPs for treating GBM.

Fibroblasts and macrophages play key roles in the development of hepatocellular carcinoma (HCC). However, cross-talk between these two kinds of cells has not been well studied. Endosialin (CD248/TEM1) is a transmembrane glycoprotein that is expressed in certain cancer cells, tumor stromal cells, and pericytes. In this study, we found that endosialin is mainly expressed in cancer-associated fibroblasts (CAF) in HCC and its expression inversely correlates with patient prognosis. Endosialin interacted with CD68 to recruit macrophages and regulated expression of GAS6 in CAFs to mediate M2 polarization of macrophages. The fully human antibody IgG78 bound glycosylated endosialin and induced its internalization in CAFs, thus weakening the cross-talk between CAFs and macrophages. In subcutaneous and orthotopic xenograft models of HCC in nude mice, treatment with IgG78 significantly inhibited tumor growth. These results indicate that endosialin-positive CAFs promote HCC progression and highlight IgG78 as a promising therapeutic candidate for HCC treatment. SIGNIFICANCE: These findings highlight CAF-expressed endosialin as a primary regulator of macrophage recruitment and polarization and demonstrate endosialin inhibition as a potential treatment strategy for HCC. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/18/3892/F1.large.jpg.

Endothelial cells (ECs) play an important role in tumor progression. Currently, the main target of anti-angiogenic therapy is the vascular endothelial growth factor (VEGF) pathway. Some patients do benefit from anti-VEGF/VEGFR therapy; however, a large number of patients do not have response or acquire drug resistance after treatment. Moreover, anti-VEGF/VEGFR therapy may lead to nephrotoxicity and cardiovascular-related side effects due to its action on normal ECs. Therefore, it is necessary to identify targets that are specific to tumor ECs and could be applied to various cancer types. We integrated single-cell RNA sequencing data from six cancer types and constructed a multi-cancer EC atlas to decode the characteristic of tumor ECs. We found that tip-like ECs mainly exist in tumor tissues but barely exist in normal tissues. Tip-like ECs are involved in the promotion of tumor angiogenesis and inhibition on anti-tumor immune responses. Moreover, tumor cells, myeloid cells, and pericytes are the main sources of pro-angiogenic factors. High proportion of tip-like ECs is associated with poor prognosis in multiple cancer types. We also identified that prostate-specific membrane antigen (PSMA) is a specific marker for tip-like ECs in all the cancer types we studied. In summary, we demonstrate that tip-like ECs are the main differential EC subcluster between tumors and normal tissues. Tip-like ECs may promote tumor progression through promoting angiogenesis while inhibiting anti-tumor immune responses. PSMA was a specific marker for tip-like ECs, which could be used as a potential target for the diagnosis and treatment of non-prostate cancers.

Figure 1. RSK4 is highly expressed in ESCC CSCs. (A) RSK4 protein was highly expressed in ESCC rather than in esophageal adenocarcinoma (EA) compared with expression in corresponding nontumor tissues. Representative IHC images are shown in Supplemental Figure 1A. (B) mRNA levels of RPS6KA6 in 30 pairs of ESCC samples and adjacent nontumor tissues were determined by real-time PCR. GAPDH was used as a loading control. (C) Western blot analysis and quantification of RSK4 expression in ESCC tumor tissues (T) and adjacent nontumor tissues (N) from 30 patients. The results for the other samples are presented in Supplemental Figure 1B. Protein expression was normalized to -actin levels. (D) Representative IHC images and H-score of RSK4 protein expression in ESCC tumor tissues and adjacent nontumor tissues. Scale bars: 100 m. (E) Kaplan-Meier estimation of ESCC OS and PFS based on the RSK4 expression levels in the Xijing cohort. (F) Correlation between RPS6KA6 and ALDH1A1 mRNA expression in 30 ESCC patients. (G) Representative IHC images of RSK4 and ALDH1 protein expression in patients with ESCC from the Xijing cohort. Scale bars: 100 m. Correlation of IHC data on RSK4 and ALDH1 protein expression in 59 ESCC patients. (H) RSK4 was preferentially expressed in tumor spheres compared with nonspheres, and elevated RSK4 expression was detected in CD90 + -or CD271 + -enriched cell populations compared with the CD90 -or CD271 -cell subsets as assessed by realtime PCR (n = 3 independent experiments) and immunoblotting. Data represent the mean SD. *P < 0.05, **P < 0.01, and ***P < 0.001. Differences were tested using a paired (B-D) and unpaired (H) 2-sided Student's t test, 1-way ANOVA with Tukey's post hoc test (A), and log-rank test (E). The correlation was determined by Pearson's correlation test (F and G).