Jun Mi

SLC25A10, the mitochondrial dicarboxylate carrier, plays a crucial role in mitochondrial metabolism and protects against liver lipotoxicity. Moreover, its frequent amplification or mutation in cancers, particularly hepatocellular carcinoma (HCC), correlates with a poor prognosis. This study aimed to investigate the role of SLC25A10 in chemotherapy resistance in HCC and elucidate the underlying mechanisms. In this study, we found that hypoxia increased SLC25A10 expression with a preferential shift toward isoform 3 in HCC. This isoform interacts with the nuclear transporter IPO7 to translocate into the nucleus, where it binds to transcription factor CEBPB. This interaction upregulates the transcription of the anti-apoptotic gene BCL2A1 , thereby enhancing HCC cell resistance to the chemotherapeutic agent, etoposide. Notably, disruption of the SLC25A10 isoform 3-IPO7 interaction significantly sensitized HCC tumors to etoposide in vivo, suggesting that targeting this interaction could be a promising therapeutic strategy to improve chemotherapy efficacy in HCC. This study reveals a novel nuclear function of the mitochondrial dicarboxylate carrier SLC25A10 in transcriptional regulation under hypoxic conditions, distinct from its canonical mitochondrial role. These findings expand our understanding of SLC25A10 biology and uncover a previously unrecognized mechanism that drives hypoxia-induced chemoresistance in HCC. Our findings suggest that SLC25A10 is a potential therapeutic target to overcome drug resistance in HCC.

Cancer-associated fibroblasts (CAFs) are activated fibroblasts that secrete numerous cytokines and chemokines to accelerate tumor progression. However, the mechanism underlying cytokine production by CAFs remains unclear. This study reports that CAFs isolated from colon cancer tissue, TGF-β1-induced CAFs, or HCT116 co-cultured CAFs secrete more cytokines and growth factors represented by IGF1, ELN, and SFRP2. Mechanistic investigations demonstrate that aerobic glycolysis metabolites fumarate and succinate can induce the transcription of IGF1, ELN, and SFRP2 in CAFs, while α-ketoglutarate (α-KG) can antagonize the induction effect of fumarate and succinate. Moreover, the downregulation of KDM6A in CAFs is observed compared to quiescent fibroblasts (NAFs). Additionally, integrated analysis of ATAC sequencing and RNA sequencing revealed altered chromatin structure during fibroblast activation. CUT-tag sequencing and co-IP assays demonstrate that KDM6A is bound to WDR5, facilitating its association with the COMPASS complex and the polycomb repressive complex at the expected target loci. Depletion of KDM6A disrupts the homeostasis between polycomb and COMPASS complexes, leading to an increase in the expression of IGF1, ELN, and SFRP2. However, the inhibitor GSK-J4, specific for both KDM6A and KDM6B, reduces IGF1 expression, indicating that KDM6B compensates for the demethylase function of KDM6A but cannot replace KDM6A to maintain the homeostasis of COMPASS and polycomb repressive complexes. These findings suggest a metabolism-related epigenetic mechanism for cytokine expression, where reduced KDM6A levels enhance the tumor-promoting effect of CAFs. This may provide insights into why colon cancer is more prevalent in men than in women, since KDM6A is an X-chromosome-associated gene.

Normal erythropoiesis requires the precise regulation of gene expression patterns, and transcription cofactors play a vital role in this process. Deregulation of cofactors has emerged as a key mechanism contributing to erythroid disorders. Through gene expression profiling, we found HES6 as an abundant cofactor expressed at gene level during human erythropoiesis. HES6 physically interacted with GATA1 and influenced the interaction of GATA1 with FOG1. Knockdown of HES6 impaired human erythropoiesis by decreasing GATA1 expression. Chromatin immunoprecipitation and RNA sequencing revealed a rich set of HES6- and GATA1-co-regulated genes involved in erythroid-related pathways. We also discovered a positive feedback loop composed of HES6, GATA1 and STAT1 in the regulation of erythropoiesis. Notably, erythropoietin (EPO) stimulation led to up-regulation of these loop components. Increased expression levels of loop components were observed in CD34⁺ cells of polycythemia vera patients. Interference by either HES6 knockdown or inhibition of STAT1 activity suppressed proliferation of erythroid cells with the JAK2^V617F mutation. We further explored the impact of HES6 on polycythemia vera phenotypes in mice. The identification of the HES6–GATA1 regulatory loop and its regulation by EPO provides novel insights into human erythropoiesis regulated by EPO/EPOR and a potential therapeutic target for the management of polycythemia vera.

Extramedullary infiltration (EMI) is a concomitant manifestation that may indicate poor outcome of acute myeloid leukemia (AML). The underlying mechanism remains poorly understood and therapeutic options are limited. Here, we employed single-cell RNA sequencing on bone marrow (BM) and EMI samples from a patient with AML presenting pervasive leukemia cutis. A complement C1Q+ macrophage-like leukemia subset, which was enriched within cutis and existed in BM before EMI manifestations, was identified and further verified in multiple patients with AML. Genomic and transcriptional profiling disclosed mutation and gene expression signatures of patients with EMI that expressed high levels of C1Q. RNA sequencing and quantitative proteomic analysis revealed expression dynamics of C1Q from primary to relapse. Univariate and multivariate analysis demonstrated adverse prognosis significance of C1Q expression. Mechanistically, C1Q expression, which was modulated by transcription factor MAF BZIP transcription factor B, endowed leukemia cells with tissue infiltration ability, which could establish prominent cutaneous or gastrointestinal EMI nodules in patient-derived xenograft and cell line–derived xenograft models. Fibroblasts attracted migration of the C1Q+ leukemia cells through C1Q–globular C1Q receptor recognition and subsequent stimulation of transforming growth factor β1. This cell-to-cell communication also contributed to survival of C1Q+ leukemia cells under chemotherapy stress. Thus, C1Q served as a marker for AML with adverse prognosis, orchestrating cancer infiltration pathways through communicating with fibroblasts and represents a compelling therapeutic target for EMI.

Objectives: Glutamic pyruvate transaminase (GPT2) catalyzes the reversible transamination between alanine and α-ketoglutarate (α-KG) to generate pyruvate and glutamate during cellular glutamine catabolism. The glutamate could be further converted to γ-aminobutyric acid (GABA). However, the role of GPT2 in tumor metastasis remains unclear.

In this article, authors show that metabolically cooperating cells shape their metabolic environment to achieve lifespan extension. The paper is clearly organized and provides new ideas for the study of cell metabolism, but I still have several quest...

Background The ⁶⁸Ga-labelled FAPI provides new oncology imaging option other than ¹⁸F-FDG-PET. However, it's unclear about whether the FAPI-PET distinguishes malignancy from benign lesions. Methods We established an AOM/DSS-induced rat colorectal tumor model. A double PET/CT tracer of ⁶⁸Ga-FAPI-04 and ¹⁸F-FDG was used in the rat colorectal tumor model. Histological examination, immunohistochemistry staining, and radioautography were performed in this study. Results ⁶⁸Ga-FAPI PET imaging distinguishes neoplasia from inflammatory lesions in an AOM/DSS-induced rat colorectal tumor model, and FAPI accumulation gradually increases along with tumor progression. An inflammatory lesion did not interfere with ⁶⁸Ga-FAPI PET imaging. Conclusion The ⁶⁸Ga-FAPI-04 PET distinguishes malignant tumors from inflammatory lesions by detecting FAP in a rat colorectal tumor model, suggesting that ⁶⁸Ga-FAPI-04 PET is a better diagnostic tool than ¹⁸F-FDG PET, at least to colorectal cancer patients.

Tryptophan metabolism is an essential regulator of tumor immune evasion. However, the effect of tryptophan metabolism on cancer cells remains largely unknown. Here, we find that tumor cells have distinct responses to tryptophan deficiency in terms of cell growth, no matter hepatocellular carcinoma (HCC) cells, lung cancer cells, or breast cancer cells. Further study shows that ERRFI1 is upregulated in sensitive HCC cells, but not in resistant HCC cells, in response to tryptophan deficiency, and ERRFI1 expression level positively correlates with HCC patient overall survival. ERRFI1 knockdown recovers tryptophan deficiency-suppressed cell growth of sensitive HCC cells. In contrast, ERRFI1 overexpression sensitizes resistant HCC cells to tryptophan deficiency. Moreover, ERRFI1 induces apoptosis by binding PDCD2 in HCC cells, PDCD2 knockdown decreases the ERRFI1-induced apoptosis in HCC cells. Thus, we conclude that ERRFI1-induced apoptosis increases the sensitivity of HCC cells to tryptophan deficiency and ERRFI1 interacts with PDCD2 to induce apoptosis in HCC cells.