Targeting the glutamine-arginine-proline metabolism axis in cancer.

Metabolic abnormalities are an important feature of tumours. The glutamine-arginine-proline axis is an important node of cancer metabolism and plays a major role in amino acid metabolism. This axis also acts as a scaffold for the synthesis of other nonessential amino acids and essential metabolites. In this paper, we briefly review (1) the glutamine addiction exhibited by tumour cells with accelerated glutamine transport and metabolism; (2) the methods regulating extracellular glutamine entry, intracellular glutamine synthesis and the fate of intracellular glutamine; (3) the glutamine, proline and arginine metabolic pathways and their interaction; and (4) the research progress in tumour therapy targeting the glutamine-arginine-proline metabolic system, with a focus on summarising the therapeutic research progress of strategies targeting of one of the key enzymes of this metabolic system, P5CS (ALDH18A1). This review provides a new basis for treatments targeting the metabolic characteristics of tumours.

Spindle apparatus coiled-coil protein 1 (SPDL1) serves as a novel prognostic biomarker in triple-negative breast cancer.

BACKGROUND: Triple-negative breast cancer (TNBC) has a poor prognosis, an ineffective diagnosis, and a high degree of aggressiveness. Therefore, novel therapeutic targets for TNBC urgently need to be identified. METHODS: Through a series of bioinformatics analyses, including analysis of differential gene expression, protein-protein interaction (PPI) network, univariate cox regression, immune infiltration, pathway enrichment, etc, as well as auxiliary immunohistochemistry (IHC) and protein quantitativae analysis, to explore prognostic marker for TNBC. RESULTS: In TNBC tissues, we found that SPDL1 (CCDC99) was considerably overexpressed at both the mRNA and protein levels compared to that in normal and non-TNBC tissues. Additionally, we found that SPDL1-high expression was strongly linked to poor prognosis in TNBC patients. Excessive SPDL1 expression was positively correlated with tumor growth and strongly linked to the cell cycle, DNA replication, and the p53 signaling pathway. In addition, CIBERSORT analysis revealed that SPDL1 can affect the tumor immune microenvironment (TME) in TNBC, encourage the development of TNBC and act as a potential prognostic biomarker for TNBC. Patients with SPDL1-high expression were more sensitive to AZD8055. Notably, we discovered that SPDL1 is highly expressed in the majority of malignancies and may have an impact on the pancancer prognosis. CONCLUSIONS: SPDL1 can serve as a novel prognostic marker for TNBC and pancancer patients.

Models for evaluating glioblastoma invasion along white matter tracts.

White matter tracts (WMs) are one of the main invasion paths of glioblastoma multiforme (GBM). The lack of ideal research models hinders our understanding of the details and mechanisms of GBM invasion along WMs. To date, many potential in vitro models have been reported; nerve fiber culture models and nanomaterial models are biocompatible, and the former have electrically active neurons. Brain slice culture models, organoid models, and microfluidic chip models can simulate the real brain and tumor microenvironment (TME), which contains a variety of cell types. These models are closer to the real in vivo environment and are helpful for further studying not only invasion along WMs by GBM, but also perineural invasion and brain metastasis by solid tumors.

Glioma-associated mesenchymal stem cells.

Recent studies have revealed that glioma-associated mesenchymal stem cells play instrumental roles in tumorigenesis and tumour progression and cannot be ignored as a cellular component of the glioma microenvironment. Nevertheless, the origin of these cells and their roles are poorly understood. The only relevant studies have shown that glioma-associated mesenchymal stem cells play a large role in promoting tumour proliferation, invasion and angiogenesis. This review provides a comprehensive summary of their discovery and definition, origin, differences from other tissue-derived mesenchymal stem cells, spatial distribution, functions and prognostic and therapeutic opportunities to deepen the understanding of these cells and provide new insight into the treatment of glioma.

Mitochondria in cancer stem cells: Achilles heel or hard armor.

Previous studies have shown that mitochondria play core roles in not only cancer stem cell (CSC) metabolism but also the regulation of CSC stemness maintenance and differentiation, which are key regulators of cancer progression and therapeutic resistance. Therefore, an in-depth study of the regulatory mechanism of mitochondria in CSCs is expected to provide a new target for cancer therapy. This article mainly introduces the roles played by mitochondria and related mechanisms in CSC stemness maintenance, metabolic transformation, and chemoresistance. The discussion mainly focuses on the following aspects: mitochondrial morphological structure, subcellular localization, mitochondrial DNA, mitochondrial metabolism, and mitophagy. The manuscript also describes the recent clinical research progress on mitochondria-targeted drugs and discusses the basic principles of their targeted strategies. Indeed, an understanding of the application of mitochondria in the regulation of CSCs will promote the development of novel CSC-targeted strategies, thereby significantly improving the long-term survival rate of patients with cancer.

ALDEFLUOR activity, ALDH isoforms, and their clinical significance in cancers.

High aldehyde dehydrogenase (ALDH) activity is a metabolic feature of adult stem cells and various cancer stem cells (CSCs). The ALDEFLUOR system is currently the most commonly used method for evaluating ALDH enzyme activity in viable cells. This system is applied extensively in the isolation of normal stem cells and CSCs from heterogeneous cell populations. For many years, ALDH1A1 has been considered the most important subtype among the 19 ALDH family members in determining ALDEFLUOR activity. However, in recent years, studies of many types of normal and tumour tissues have demonstrated that other ALDH subtypes can also significantly influence ALDEFLUOR activity. In this article, we briefly review the relationships between various members of the ALDH family and ALDEFLUOR activity. The clinical significance of these ALDH isoforms in different cancers and possible directions for future studies are also summarised.

Beyond metabolic waste: lysine lactylation and its potential roles in cancer progression and cell fate determination.

BACKGROUND: Lactate is an important metabolite derived from glycolysis under physiological and pathological conditions. The Warburg effect reveals the vital role of lactate in cancer progression. Numerous studies have reported crucial roles for lactate in cancer progression and cell fate determination. Lactylation, a novel posttranslational modification (PTM), has provided a new opportunity to investigate metabolic epigenetic regulation, and studies of this process have been initiated in a wide range of cancer cells, cancer-associated immune cells, and embryonic stem cells. CONCLUSION: Lactylation is a novel and interesting mechanism of lactate metabolism linked to metabolic rewiring and epigenetic remodeling. It is a potential and hopeful target for cancer therapy. Here, we summarize the discovery of lactylation, the mechanisms of site modification, and progress in research on nonhistone lactylation. We focus on the potential roles of lactylation in cancer progression and cell fate determination and the possible therapeutic strategies for targeting lysine lactylation. Finally, we suggest some future research topics on lactylation to inspire some interesting ideas.

Construction of a solid Cox model for AML patients based on multiomics bioinformatic analysis.

Acute myeloid leukemia (AML) is a highly heterogeneous hematological malignancy. The bone marrow (BM) microenvironment in AML plays an important role in leukemogenesis, drug resistance and leukemia relapse. In this study, we aimed to identify reliable immune-related biomarkers for AML prognosis by multiomics analysis. We obtained expression profiles from The Cancer Genome Atlas (TCGA) database and constructed a LASSO-Cox regression model to predict the prognosis of AML using multiomics bioinformatic analysis data. This was followed by independent validation of the model in the GSE106291 (n=251) data set and mutated genes in clinical samples for predicting overall survival (OS). Molecular docking was performed to predict the most optimal ligands to the genes in prognostic model. The single-cell RNA sequence dataset GSE116256 was used to clarify the expression of the hub genes in different immune cell types. According to their significant differences in immune gene signatures and survival trends, we concluded that the immune infiltration-lacking subtype (IL type) is associated with better prognosis than the immune infiltration-rich subtype (IR type). Using the LASSO model, we built a classifier based on 5 hub genes to predict the prognosis of AML (risk score = -0.086×ADAMTS3 + 0.180×CD52 + 0.472×CLCN5 - 0.356×HAL + 0.368×ICAM3). In summary, we constructed a prognostic model of AML using integrated multiomics bioinformatic analysis that could serve as a therapeutic classifier.

ASCL2 Maintains Stemness Phenotype through ATG9B and Sensitizes Gliomas to Autophagy Inhibitor.

Autophagy is a highly conserved process that is vital for tumor progression and treatment response. Although autophagy is proposed to maintain the stemness phenotype in adult diffuse glioma, the molecular basis of the link between autophagy and stemness is poorly understood, which makes it impossible to effectively screen for the population that will benefit from autophagy-targeted treatment. Here, ATG9B as essential for self-renewal capacity and tumor-propagation potential is identified. Notably, ASCL2 transcriptionally regulates the expression of ATG9B to maintain stemness properties. The ASCL2-ATG9B axis is an independent prognostic biomarker and indicator of autophagic activity. Furthermore, the highly effective blood-brain barrier (BBB)-permeable autophagy inhibitor ROC-325, which can significantly inhibit the progression of ASCL2-ATG9B axisHigh gliomas as a single agent is investigated. These data demonstrate that a new ASCL2-ATG9B signaling axis is crucial for maintaining the stemness phenotype and tumor progression, revealing a potential autophagy inhibition strategy for adult diffuse gliomas.

CRIPTO Is a Marker of Chemotherapy-Induced Stem Cell Expansion in Non-Small Cell Lung Cancer.

Chemotherapy is the mainstay for the treatment of non-small cell lung cancer (NSCLC). However, NSCLC cells are either intrinsically chemoresistant or rapidly develop therapy resistance. Cancer stem cells (CSCs) are widely recognized as the cell population responsible for resistance to systemic therapies, but the molecular responses of CSCs to chemotherapeutic agents are largely unknown. We identified the embryonic protein CRIPTO in stem cell-enriched spheroid cultures of adenocarcinoma (AC) and squamous cell carcinoma (SCC) derived from NSCLC surgical specimens. The CRIPTO-positive population had increased clonogenic capacity and expression of stem cell-related factors. Stemness-related properties were also obtained with forced CRIPTO expression, whereas CRIPTO downregulation resulted in cell cycle blockade and CSCs death. Cell populations positive and negative for CRIPTO expression were interconvertible, and interfering with their reciprocal equilibrium resulted in altered homeostasis of cell expansion both in spheroid cultures and in tumor xenografts. Chemotherapy treatment of NSCLC cells resulted in reduction of cell number followed by increased CRIPTO expression and selective survival of CRIPTO-positive cells. In NSCLC tumor xenografts, chemotherapeutic agents induced partial cell death and tumor stabilization followed by CRIPTO overexpression and tumor progression. Altogether, these findings indicate CRIPTO as a marker of lung CSCs possibly implicated in cancer cell plasticity and post-chemotherapy tumor progression.

An aldehyde dehydrogenase 1A3 inhibitor attenuates the metastasis of human colorectal cancer.

Metastasis is the leading cause of death for patients with colorectal cancer (CRC). The development of therapeutic regimens that selectively inhibit the biological processes involved in CRC cell dissemination is important. We used multiple Affymetrix DNA microarray hybridization datasets to identify genes related to metastasis and have significant prognostic value for patients with CRC. Quantitative real-time PCR, immunofluorescent and immunohistochemical staining were used to evaluate mRNA and protein expression. The function of aldehyde dehydrogenase 1A3 (ALDH1A3) in invasion was assessed by performing transwell assays and animal experiments. Real-time PCR, luciferase reporter assays, and western blotting were used to identify the genes regulated by ALDH1A3. Molecular docking, MTS assays, cellular thermal shift assays, isothermal titration calorimetry, microscale thermophoresis, and enzymatic activity assays were used to screen and verify the efficacy of the ALDH1A3-specific inhibitor YD1701 (dibenzo-30-crown10-ether). Finally, subcutaneous or orthotopic xenograft models were established to investigate the therapeutic potential of YD1701. Human ALDH1A3 was identified to correlate with a metastatic phenotype in CRC cells and a poor patient prognosis. Moreover, ALDH1A3 upregulated the expression of ZEB1 and SNAI2 by inhibiting miR-200 family members. The ALDH1A3-specific inhibitor YD1701 was screened, attenuated the invasion of CRC cells in vitro, and prolonged the survival of mice bearing subcutaneous or orthotopic xenografts. Our results show that ALDH1A3 promotes invasion and metastasis via the miR-200-ZEB1/SANI2 axis and is thus a plausible marker for predicting CRC progression. Inhibiting ALDH1A3 with the identified compound YD1701 might represent an effective therapeutic approach to prevent the metastasis of CRC.

Glioma invasion along white matter tracts: A dilemma for neurosurgeons.

Invasive growth along white matter (WM) tracts is one of the most prominent clinicopathological features of glioma and is also an important reason for surgical treatment failure in glioma patients. A full understanding of relevant clinical features and mechanisms is of great significance for finding new therapeutic targets and developing new treatment regimens and strategies. Herein, we review the imaging and histological characteristics of glioma patients with WM tracts invasion and summarize the possible molecular mechanism. On this basis, we further discuss the correlation between glioma molecular typing, radiotherapy and tumor treating fields (TTFields) and the invasion of glioma along WM tracts.

The role of lysosomes in cancer development and progression.

Lysosomes are an important component of the inner membrane system and participate in numerous cell biological processes, such as macromolecular degradation, antigen presentation, intracellular pathogen destruction, plasma membrane repair, exosome release, cell adhesion/migration and apoptosis. Thus, lysosomes play important roles in cellular activity. In addition, previous studies have shown that lysosomes may play important roles in cancer development and progression through the abovementioned biological processes and that the functional status and spatial distribution of lysosomes are closely related to cancer cell proliferation, energy metabolism, invasion and metastasis, immune escape and tumor-associated angiogenesis. Therefore, identifying the factors and mechanisms that regulate the functional status and spatial distribution of lysosomes and elucidating the relationship between lysosomes and the development and progression of cancer can provide important information for cancer diagnosis and prognosis prediction and may yield new therapeutic targets. This study briefly reviews the above information and explores the potential value of lysosomes in cancer therapy.

NADP modulates RNA m6A methylation and adipogenesis via enhancing FTO activity.

Metabolism is often regulated by the transcription and translation of RNA. In turn, it is likely that some metabolites regulate enzymes controlling reversible RNA modification, such as N6-methyladenosine (m6A), to modulate RNA. This hypothesis is at least partially supported by the findings that multiple metabolic diseases are highly associated with fat mass and obesity-associated protein (FTO), an m6A demethylase. However, knowledge about whether and which metabolites directly regulate m6A remains elusive. Here, we show that NADP directly binds FTO, independently increases FTO activity, and promotes RNA m6A demethylation and adipogenesis. We screened a set of metabolites using a fluorescence quenching assay and NADP was identified to remarkably bind FTO. In vitro demethylation assays indicated that NADP enhances FTO activity. Furthermore, NADP regulated mRNA m6A via FTO in vivo, and deletion of FTO blocked NADP-enhanced adipogenesis in 3T3-L1 preadipocytes. These results build a direct link between metabolism and RNA m6A demethylation.

Triple-negative breast cancer molecular subtyping and treatment progress.

Triple-negative breast cancer (TNBC), a specific subtype of breast cancer that does not express estrogen receptor (ER), progesterone receptor (PR), or human epidermal growth factor receptor 2 (HER-2), has clinical features that include high invasiveness, high metastatic potential, proneness to relapse, and poor prognosis. Because TNBC tumors lack ER, PR, and HER2 expression, they are not sensitive to endocrine therapy or HER2 treatment, and standardized TNBC treatment regimens are still lacking. Therefore, development of new TNBC treatment strategies has become an urgent clinical need. By summarizing existing treatment regimens, therapeutic drugs, and their efficacy for different TNBC subtypes and reviewing some new preclinical studies and targeted treatment regimens for TNBC, this paper aims to provide new ideas for TNBC treatment.

Icaritin enhances the efficacy of cetuximab against triple-negative breast cancer cells.

Triple-negative breast cancer (TNBC) has a greater risk of recurrence and metastasis along with a worse prognosis compared with other subtypes of breast cancer. Studies have revealed that mitogenic estrogen signaling is involved in the malignant proliferation of TNBC cells through a novel variant of the estrogen receptor, estrogen receptor α-36 (ER-α36). The results of the present study demonstrated that knockdown of ER-α36 expression in TNBC cells using short hairpin RNA inhibited rapid estrogen signaling bypass activation of the PI3K/AKT signaling pathway. Moreover, the ER-α36 modulator icaritin inhibited the proliferation of TNBC cells both in vitro and in vivo. Here, it was revealed that the combination of icaritin and cetuximab, a therapeutic epidermal growth factor receptor (EGFR) neutralizing antibody, induced apoptosis and inhibited cell proliferation synergistically in TNBC cells. The results of the present study improved the understanding of the underlying mechanisms of TNBC progression and supported the therapeutic potential of combined treatment targeting the ER-α36 and EGFR.

Inhibition of the ALDH18A1-MYCN positive feedback loop attenuates MYCN-amplified neuroblastoma growth.

MYCN-amplified neuroblastoma (NB) is characterized by poor prognosis, and directly targeting MYCN has proven challenging. Here, we showed that aldehyde dehydrogenase family 18 member A1 (ALDH18A1) exerts profound impacts on the proliferation, self-renewal, and tumorigenicity of NB cells and is a potential risk factor in patients with NB, especially those with MYCN amplification. Mechanistic studies revealed that ALDH18A1 could both transcriptionally and posttranscriptionally regulate MYCN expression, with MYCN reciprocally transactivating ALDH18A1 and thus forming a positive feedback loop. Using molecular docking and screening, we identified an ALDH18A1-specific inhibitor, YG1702, and demonstrated that pharmacological inhibition of ALDH18A1 was sufficient to induce a less proliferative phenotype and confer tumor regression and prolonged survival in NB xenograft models, providing therapeutic insights into the disruption of this reciprocal regulatory loop in MYCN-amplified NB.

CCL8 secreted by tumor-associated macrophages promotes invasion and stemness of glioblastoma cells via ERK1/2 signaling.

Tumor-associated macrophages (TAMs) constitute a large population of glioblastoma and facilitate tumor growth and invasion of tumor cells, but the underlying mechanism remains undefined. In this study, we demonstrate that chemokine (C-C motif) ligand 8 (CCL8) is highly expressed by TAMs and contributes to pseudopodia formation by GBM cells. The presence of CCL8 in the glioma microenvironment promotes progression of tumor cells. Moreover, CCL8 induces invasion and stem-like traits of GBM cells, and CCR1 and CCR5 are the main receptors that mediate CCL8-induced biological behavior. Finally, CCL8 dramatically activates ERK1/2 phosphorylation in GBM cells, and blocking TAM-secreted CCL8 by neutralized antibody significantly decreases invasion of glioma cells. Taken together, our data reveal that CCL8 is a TAM-associated factor to mediate invasion and stemness of GBM, and targeting CCL8 may provide an insight strategy for GBM treatment.