SIRT1/PGC1α-Dependent Increase in Oxidative Phosphorylation Supports Chemotherapy Resistance of Colon Cancer

MEF2A, a gene associated with mitochondrial biogenesis, promotes drug resistance in gastric cancer

Chemotherapeutic resistance is a major obstacle to the effectiveness of cisplatin-based chemotherapy for gastric cancer (GC), leading to treatment failure and poor survival rates. However, the underlying mechanisms are not fully understood. Our study demonstrated that the transcription factor myocyte enhancer factor 2A (MEF2A) plays a role in chemotherapeutic drug resistance by regulating the transcription of PGC1α and KEAP1, promoting mitochondrial biogenesis. It was found that increased MEF2A expression is linked with poor prognosis, cisplatin insensitivity, and mitochondrial function in GC. MEF2A overexpression significantly decreases GC cell sensitivity in vitro and in vivo, while MEF2A knockdown enhances the sensitivity to cisplatin. Mechanistically, MEF2A activates the transcription of PGC1α, leading to increased mitochondrial biogenesis. In addition, MEF2A inhibits KEAP1 transcription, reduces NRF2 ubiquitination degradation, and activates the KEAP1/NRF2 signaling pathway, which modulates the reactive oxygen species level. The present study identifies MEF2A as a new critical oncogene involved in GC chemoresistance, suggesting a novel therapeutic target for GC.

Unveiling chemotherapy-induced immune landscape remodeling and metabolic reprogramming in lung adenocarcinoma by scRNA-sequencing

Chemotherapy is widely used to treat lung adenocarcinoma (LUAD) patients comprehensively. Considering the limitations of chemotherapy due to drug resistance and other issues, it is crucial to explore the impact of chemotherapy and immunotherapy on these aspects. In this study, tumor samples from nine LUAD patients, of which four only received surgery and five received neoadjuvant chemotherapy, were subjected to scRNA-seq analysis. In vitro and in vivo assays, including flow cytometry, immunofluorescence, Seahorse assay, and tumor xenograft models, were carried out to validate our findings. A total of 83,622 cells were enrolled for subsequent analyses. The composition of cell types exhibited high heterogeneity across different groups. Functional enrichment analysis revealed that chemotherapy drove significant metabolic reprogramming in tumor cells and macrophages. We identified two subtypes of macrophages: Anti-mac cells (CD45+CD11b+CD86+) and Pro-mac cells (CD45+CD11b+ARG +) and sorted them by flow cytometry. The proportion of Pro-mac cells in LUAD tissues increased significantly after neoadjuvant chemotherapy. Pro-mac cells promote tumor growth and angiogenesis and also suppress tumor immunity. Moreover, by analyzing the remodeling of T and B cells induced by neoadjuvant therapy, we noted that chemotherapy ignited a relatively more robust immune cytotoxic response toward tumor cells. Our study demonstrates that chemotherapy induces metabolic reprogramming within the tumor microenvironment of LUAD, particularly affecting the function and composition of immune cells such as macrophages and T cells. We believe our findings will offer insight into the mechanisms of drug resistance and provide novel therapeutic targets for LUAD in the future.

Mitochondrial unfolded protein response-dependent β-catenin signaling promotes neuroendocrine prostate cancer

The mitochondrial unfolded protein response (UPRmt) maintains mitochondrial quality control and proteostasis under stress conditions. However, the role of UPRmt in aggressive and resistant prostate cancer is not clearly defined. We show that castration-resistant neuroendocrine prostate cancer (CRPC-NE) harbored highly dysfunctional oxidative phosphorylation (OXPHOS) Complexes. However, biochemical and protein analyses of CRPC-NE tumors showed upregulation of nuclear-encoded OXPHOS proteins and UPRmt in this lethal subset of prostate cancer suggestive of compensatory upregulation of stress signaling. Genetic deletion and pharmacological inhibition of the main chaperone of UPRmt heat shock protein 60 (HSP60) reduced neuroendocrine prostate cancer (NEPC) growth in vivo as well as reverted NEPC cells to a more epithelial-like state. HSP60-dependent aggressive NEPC phenotypes was associated with upregulation of β-catenin signaling both in cancer cells and in vivo tumors. HSP60 expression rendered enrichment of aggressive prostate cancer signatures and metastatic potential were inhibited upon suppression of UPRmt. We discovered that UPRmt promoted OXPHOS functions including mitochondrial bioenergetics in CRPC-NE via regulation of β-catenin signaling. Mitochondrial biogenesis facilitated cisplatin resistance and inhibition of UPRmt resensitizes CRPC-NE cells to cisplatin. Together, our findings demonstrated that UPRmt promotes mitochondrial health via upregulating β-catenin signaling and UPRmt represents viable therapeutic target for NEPC.

Targeting Radiation Resistance in Oesophageal Adenocarcinoma with Pyrazinib-Functionalised Gold Nanoparticles

Background/Objectives: Only 20-30% of oesophageal adenocarcinoma (OAC) patients achieve a complete response to neoadjuvant chemo-radiotherapy for locally advanced tumours. Enhancing the response to radiation therapy is critical for improving outcomes in this aggressive cancer. Pyrazinib (P3) is a promising compound with radiosensitizing, anti-angiogenic, anti-inflammatory, and anti-metabolic properties. However, its limited solubility and bioavailability have hindered its therapeutic potential.

METHODS

To overcome these limitations, pyrazinib was conjugated with gold nanoparticles (AuNP-P3), creating a novel formulation designed to enhance solubility, maintain bioactivity, and enable targeted delivery to tumour sites.

RESULTS

In an isogenic model of OAC radioresistance, AuNP-P3 significantly reduced the surviving fraction following irradiation, demonstrating its radiosensitizing properties. It also reduced mitochondrial metabolism and modulated the secretion of inflammatory mediators in both in vitro models of OAC radioresistance and human ex vivo OAC tumour explants. Furthermore, AuNP-P3 exhibited potent anti-angiogenic activity, significantly inhibiting blood vessel formation in vivo using zebrafish embryo models.

CONCLUSIONS

These results collectively confirm that P3, in its conjugated formulation with gold nanoparticles, retains its therapeutic properties, highlighting the potential of AuNP-P3 as a novel therapeutic radiosensitizer for oesophageal adenocarcinoma and supporting its further development for clinical applications.

Metabolic reprogramming and therapeutic resistance in primary and metastatic breast cancer

Metabolic alterations, a hallmark of cancer, enable tumor cells to adapt to their environment by modulating glucose, lipid, and amino acid metabolism, which fuels rapid growth and contributes to treatment resistance. In primary breast cancer, metabolic shifts such as the Warburg effect and enhanced lipid synthesis are closely linked to chemotherapy failure. Similarly, metastatic lesions often display distinct metabolic profiles that not only sustain tumor growth but also confer resistance to targeted therapies and immunotherapies. The review emphasizes two major aspects: the mechanisms driving metabolic resistance in both primary and metastatic breast cancer, and how the unique metabolic environments in metastatic sites further complicate treatment. By targeting distinct metabolic vulnerabilities at both the primary and metastatic stages, new strategies could improve the efficacy of existing therapies and provide better outcomes for breast cancer patients.

NIT2 dampens BRD1 phase separation and restrains oxidative phosphorylation to enhance chemosensitivity in gastric cancer

5-Fluorouracil (5-FU) chemoresistance contributes to poor therapeutic response and prognosis of gastric cancer (GC), for which effective strategies to overcome chemoresistance are limited. Here, using a CRISPR-Cas9 system, we identified that nitrilase family member 2 (NIT2) reverses chemoresistance independent of its metabolic function. Depletion or low expression of NIT2 led to 5-FU resistance in GC cell lines, patient-derived organoids, and xenografted tumors. Mechanistically, NIT2 interacted with bromodomain-containing protein 1 (BRD1) to inhibit HBO1-mediated acetylation of histone H3 at lysine-14 (H3K14ac) and RELA-targeted oxidative phosphorylation (OXPHOS) gene expression. Upon 5-FU stimulation, NIT2 phosphorylation by Src at Y49 promoted the dissociation of NIT2 from BRD1, followed by binding to E3 ligase CCNB1IP1, causing autophagic degradation of NIT2. Consequently, reduced NIT2 protein resulted in BRD1 forming phase separation and binding to histone H3, as well as increased RELA stability due to suppression of inhibitor of growth family member 4-mediated RELA ubiquitination. In addition, NIT2 expression negatively correlated with H3K14ac and OXPHOS and positively correlated with the chemotherapeutic responses and prognosis of patients with GC. Our findings reveal the moonlighting function of NIT2 in chemoresistance and underscore that OXPHOS blockade by metformin enhances 5-FU chemosensitivity upon NIT2 loss.

Spatial transcriptomics reveals profound subclonal heterogeneity and T-cell dysfunction in extramedullary myeloma

ABSTRACT

Extramedullary disease (EMD) is a high-risk feature of multiple myeloma (MM) and remains a poor prognostic factor, even in the era of novel immunotherapies. Here, we applied spatial transcriptomics (RNA tomography for spatially resolved transcriptomics [tomo-seq] [n = 2] and 10x Visium [n = 12]) and single-cell RNA sequencing (n = 3) to a set of 14 EMD biopsies to dissect the 3-dimensional architecture of tumor cells and their microenvironment. Overall, infiltrating immune and stromal cells showed both intrapatient and interpatient variations, with no uniform distribution over the lesion. We observed substantial heterogeneity at the copy number level within plasma cells, including the emergence of new subclones in circumscribed areas of the tumor, which is consistent with genomic instability. We further identified the spatial expression differences between GPRC5D and TNFRSF17, 2 important antigens for bispecific antibody therapy. EMD masses were infiltrated by various immune cells, including T cells. Notably, exhausted TIM3+/PD-1+ T cells diffusely colocalized with MM cells, whereas functional and activated CD8+ T cells showed a focal infiltration pattern along with M1 macrophages in tumor-free regions. This segregation of fit and exhausted T cells was resolved in the case of response to T-cell-engaging bispecific antibodies. MM and microenvironment cells were embedded in a complex network that influenced immune activation and angiogenesis, and oxidative phosphorylation represented the major metabolic program within EMD lesions. In summary, spatial transcriptomics has revealed a multicellular ecosystem in EMD with checkpoint inhibition and dual targeting as potential new therapeutic avenues.

Breaking the barrier: Epigenetic strategies to combat platinum resistance in colorectal cancer

Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide. Platinum-based drugs, such as cisplatin and oxaliplatin, are frontline chemotherapy for CRC, effective in both monotherapy and combination regimens. However, the clinical efficacy of these treatments is often undermined by the development of drug resistance, a significant obstacle in cancer therapy. In recent years, epigenetic alterations have been recognized as key players in the acquisition of resistance to platinum drugs. Targeting these dysregulated epigenetic mechanisms with small molecules represents a promising therapeutic strategy. This review explores the complex relationship between epigenetic changes and platinum resistance in CRC, highlighting current epigenetic therapies and their effectiveness in countering resistance mechanisms. By elucidating the epigenetic underpinnings of platinum resistance, this review aims to contribute to ongoing efforts to improve treatment outcomes for CRC patients.

Bioprinted, spatially defined breast tumor microenvironment models of intratumoral heterogeneity and drug resistance

Cellular, extracellular matrix (ECM), and spatial heterogeneity of tumor microenvironments (TMEs) regulate disease progression and treatment efficacy. Developing in vitro models that recapitulate the TME promises to accelerate studies of tumor biology and identify new targets for therapy. Here, we used extrusion-based, multi-nozzle 3D bioprinting to spatially pattern triple-negative MDA-MB-231 breast cancer cells, endothelial cells (ECs), and human mammary cancer-associated fibroblasts (HMCAFs) with biomimetic ECM inks. Bioprinted models captured key features of the spatial architecture of human breast tumors, including varying-sized dense regions of cancer cells and surrounding microvessel-rich stroma. Angiogenesis and ECM stiffening occurred in the stromal area but not the cancer cell-rich (CCR) regions, mimicking pathological changes in patient samples. Transcriptomic analyses revealed upregulation of angiogenesis-related and ECM remodeling-related signatures in the stroma region and identified potential ligand-receptor (LR) mediators of these processes. Breast cancer cells in distinct parts of the bioprinted TME showed differing sensitivities to chemotherapy, highlighting environmentally mediated drug resistance. In summary, our 3D-bioprinted tumor model will act as a platform to discover integrated functions of the TME in cancer biology and therapy.

Combining Photodynamic Therapy and Targeted Drug Delivery Systems: Enhancing Mitochondrial Toxicity for Improved Cancer Outcomes

Cancer treatment continues to be a substantial problem due to tumor complexities and persistence, demanding novel therapeutic techniques. This review investigates the synergistic potential of combining photodynamic therapy (PDT) and tailored medication delivery technologies to increase mitochondrial toxicity and improve cancer outcomes. PDT induces selective cellular damage and death by activating photosensitizers (PS) with certain wavelengths of light. However, PDT's efficacy can be hampered by issues such as poor light penetration and a lack of selectivity. To overcome these challenges, targeted drug delivery systems have emerged as a promising technique for precisely delivering therapeutic medicines to tumor cells while avoiding off-target effects. We investigate how these technologies can improve mitochondrial targeting and damage, which is critical for causing cancer cell death. The combination method seeks to capitalize on the advantages of both modalities: selective PDT activation and specific targeted drug delivery. We review current preclinical and clinical evidence supporting the efficacy of this combination therapy, focusing on case studies and experimental models. This review also addresses issues such as safety, distribution efficiency, resistance mechanisms, and costs. The prospects of further research include advances in photodynamic agents and medication delivery technology, with a focus on personalized treatment. In conclusion, combining PDT with targeted drug delivery systems provides a promising frontier in cancer therapy, with the ability to overcome current treatment limits and open the way for more effective, personalized cancer treatments.

Tuning RXR Modulators for PGC1α Recruitment

The molecular activation mechanism of the nuclear retinoid X receptors (RXRs) crucially involves ligand-induced corepressor release and coactivator recruitment which mediate transcriptional repression or activation. The ability of RXR to bind diverse coactivators suggests that a coregulator-selective modulation by ligands may open an avenue to tissue- or gene-selective RXR activation. Here, we identified strong induction of peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) binding to RXR by a synthetic agonist but not by the endogenous ligand 9-cis retinoic acid. Structure-guided diversification of this lead resulted in a set of three structurally related RXR agonists with different ability to promote PGC1α recruitment in cell-free and cellular context. These results demonstrate that selective modulation of coregulator recruitment to RXR can be achieved with molecular glues and potentially open new therapeutic opportunities by targeting the ligand-induced RXR-PGC1α interaction.

SMYD2 induced PGC1α methylation promotes stemness maintenance of glioblastoma stem cells

BACKGROUND

The high fatality rate of glioblastoma (GBM) is attributed to glioblastoma stem cells (GSCs), which exhibit heterogeneity and therapeutic resistance. Metabolic plasticity of mitochondria is the hallmark of GSCs. Targeting mitochondrial biogenesis of GSCs is crucial for improving clinical prognosis in GBM patients.

METHODS

SMYD2-induced PGC1α methylation and followed nuclear export are confirmed by co-immunoprecipitation, cellular fractionation, and immunofluorescence. The effects of SMYD2/PGC1α/CRM1 axis on GSCs mitochondrial biogenesis are validated by oxygen consumption rate, ECAR, and intracranial glioma model.

RESULTS

PGC1α methylation causes the disabled mitochondrial function to maintain the stemness, thereby enhancing the radio-resistance of GSCs. SMYD2 drives PGC1α K224 methylation (K224me), which is essential for promoting the stem-like characteristics of GSCs. PGC1α K224me is preferred binding with CRM1, accelerating PGC1α nuclear export and subsequent dysfunction. Targeting PGC1α methylation exhibits significant radiotherapeutic efficacy and prolongs patient survival.

CONCLUSIONS

These findings unveil a novel regulatory pathway involving mitochondria that govern stemness in GSCs, thereby emphasizing promising therapeutic strategies targeting PGC1α and mitochondria for the treatment of GBM.

SIRT1: a novel regulator in colorectal cancer

The class-III histone deacetylase SIRT1 is the most extensively investigated sirtuin deacetylase. It is resistant to the broad deacetylase inhibitor trichostatin A and depends on oxidized nicotinamide adenine nucleotide (NAD+). SIRT1 plays a crucial role in the tumorigenesis of numerous types of cancers, including colorectal cancer (CRC). Accumulating evidence indicates that SIRT1 is a therapeutic target for CRC; however, the function and underlying mechanism of SIRT1 in CRC still need to be elucidated. Herein, we provide a detailed and updated review to illustrate that SIRT1 regulates many processes that go awry in CRC cells, such as apoptosis, autophagy, proliferation, migration, invasion, metastasis, oxidative stress, resistance to chemo-radio therapy, immune evasion, and metabolic reprogramming. Moreover, we closely link our review to the clinical practice of CRC treatment, summarizing the mechanisms and prospects of SIRT1 inhibitors in CRC therapy. SIRT1 inhibitors as monotherapy in CRC or in combination with chemotherapy, radiotherapy, and immune therapies are comprehensively discussed. From epigenetic regulation to its potential therapeutic effect, we hope to offer novel insights and a comprehensive understanding of SIRT1's role in CRC.

The Antimicrobial Peptide Tilapia Piscidin 4 Induced the Apoptosis of Bladder Cancer Through ERK/SIRT1/PGC-1α Signaling Pathway

Marine antimicrobial peptides have been demonstrated in numerous studies to possess anti-cancer properties. This research investigation aimed to explore the fundamental molecular mechanisms underlying the antitumor activity of Tilapia piscidin 4 (TP4), an antimicrobial peptide, in human bladder cancer. TP4 exhibited a remarkable inhibitory effect on the proliferation of bladder cancer cells through cell cycle arrest at the G2/M phase. Additionally, TP4 upregulated the expression of cleaved caspase-3, caspase-9, and PARP, leading to the activation of apoptotic pathways in bladder cancer cells. TP4 exhibit a marked rise in mitochondria reactive oxygen species, leading to the subsequent loss of potential for the mitochondrial membrane. Furthermore, the inhibition of mitochondrial oxidative phosphorylation resulted in a decrease in downstream ATP production. Meanwhile, TP4-treated bladder cancer cells showed an increase in Bax and ERK but a decrease in SIRT1, PGC-1α, and Bcl2. ERK activation, SIRT1/PGC-1α-axis, and TP4-induced apoptosis were all significantly reversed by the ERK inhibitor SCH772984. Finally, the inhibitory effect of TP4 on tumor growth has been confirmed in a zebrafish bladder cancer xenotransplantation model. These findings suggest that TP4 may be a potential agents for human bladder cancer through apoptosis induction, ERK activation, and the promotion of SIRT1-mediated signaling pathways.

From metabolism to malignancy: the multifaceted role of PGC1α in cancer

PGC1α, a central player in mitochondrial biology, holds a complex role in the metabolic shifts seen in cancer cells. While its dysregulation is common across major cancers, its impact varies. In some cases, downregulation promotes aerobic glycolysis and progression, whereas in others, overexpression escalates respiration and aggression. PGC1α's interactions with distinct signaling pathways and transcription factors further diversify its roles, often in a tissue-specific manner. Understanding these multifaceted functions could unlock innovative therapeutic strategies. However, challenges exist in managing the metabolic adaptability of cancer cells and refining PGC1α-targeted approaches. This review aims to collate and present the current knowledge on the expression patterns, regulators, binding partners, and roles of PGC1α in diverse cancers. We examined PGC1α's tissue-specific functions and elucidated its dual nature as both a potential tumor suppressor and an oncogenic collaborator. In cancers where PGC1α is tumor-suppressive, reinstating its levels could halt cell proliferation and invasion, and make the cells more receptive to chemotherapy. In cancers where the opposite is true, halting PGC1α's upregulation can be beneficial as it promotes oxidative phosphorylation, allows cancer cells to adapt to stress, and promotes a more aggressive cancer phenotype. Thus, to target PGC1α effectively, understanding its nuanced role in each cancer subtype is indispensable. This can pave the way for significant strides in the field of oncology.

Cancer resistance and metastasis are maintained through oxidative phosphorylation

Malignant tumors have increased energy requirements due to growth, differentiation or response to stress. A significant number of studies in recent years have described upregulation of mitochondrial genes responsible for oxidative phosphorylation (OXPHOS) in some tumors. Although OXPHOS is replaced by glycolysis in some tumors (Warburg effect), both processes can occur simultaneously during the evolution of the same malignancies. In particular, chemoresistant and/or cancer stem cells appear to find a way to activate OXPHOS and metastasize. In this paper, we discuss recent work showing upregulation of OXPHOS in chemoresistant tumors and cell models. In addition, we show an inverse correlation of OXPHOS gene expression with the survival time of cancer patients after chemotherapy and discuss combination therapies for resistant tumors.

Mitochondrion: Main organelle in orchestrating cancer escape from chemotherapy

BACKGROUND

Chemoresistance is a challenging barrier to cancer therapy, and in this context, the role of mitochondria is significant. We put emphasis on key biological characteristics of mitochondria, contributing to tumor escape from various therapies, to find the "Achilles' Heel" of cancer cells for future drug design.

RECENT FINDINGS

The mitochondrion is a dynamic organelle, and its existence is important for tumor growth. Its metabolites also cooperate with cell signaling in tumor proliferation and drug resistance.

CONCLUSION

Biological characteristics of this organelle, such as redox balance, DNA depletion, and metabolic reprogramming, provide flexibility to cancer cells to cope with therapy-induced stress.

Metabolic interventions to enhance immunotherapy and targeted therapy efficacy in advanced colorectal cancer

Current standard-of-care for metastatic colorectal cancer patients includes chemotherapy and anti-angiogenic or anti-epidermal growth factor receptor for microsatellite stable tumors and pembrolizumab for microsatellite instable tumors. However, despite the available therapies, the prognosis remains poor. In recent years, new drugs combined with immune checkpoint inhibitors have been tested in microsatellite stable metastatic colorectal cancer patients, but the benefit was modest. Here, we review the metabolic interactions between the immune microenvironment and cancer cells. More specifically, we highlight potential correlatives of tumor immune and metabolic features with transcriptomic classifications such as the Consensus Molecular Subtype. Finally, we discuss the unmet need of immune-metabolic signatures and the value of a new signature (IMMETCOLS) for guiding new strategies in metastatic colorectal cancer. We conclude that the field is ready to propose customized strategies for modifying metabolism and improving immunotherapy and targeted therapy efficacy.

The EMT factor ZEB1 paradoxically inhibits EMT in BRAF-mutant carcinomas

Despite being in the same pathway, mutations of KRAS and BRAF in colorectal carcinomas (CRCs) determine distinct progression courses. ZEB1 induces an epithelial-to-mesenchymal transition (EMT) and is associated with worse progression in most carcinomas. Using samples from patients with CRC, mouse models of KrasG12D and BrafV600E CRC, and a Zeb1-deficient mouse, we show that ZEB1 had opposite functions in KRAS- and BRAF-mutant CRCs. In KrasG12D CRCs, ZEB1 was correlated with a worse prognosis and a higher number of larger and undifferentiated (mesenchymal or EMT-like) tumors. Surprisingly, in BrafV600E CRC, ZEB1 was associated with better prognosis; fewer, smaller, and more differentiated (reduced EMT) primary tumors; and fewer metastases. ZEB1 was positively correlated in KRAS-mutant CRC cells and negatively in BRAF-mutant CRC cells with gene signatures for EMT, cell proliferation and survival, and ERK signaling. On a mechanistic level, ZEB1 knockdown in KRAS-mutant CRC cells increased apoptosis and reduced clonogenicity and anchorage-independent growth; the reverse occurred in BRAFV600E CRC cells. ZEB1 is associated with better prognosis and reduced EMT signature in patients harboring BRAF CRCs. These data suggest that ZEB1 can function as a tumor suppressor in BRAF-mutant CRCs, highlighting the importance of considering the KRAS/BRAF mutational background of CRCs in therapeutic strategies targeting ZEB1/EMT.

Notch receptor/ligand diversity: contribution to colorectal cancer stem cell heterogeneity

Cancer cell heterogeneity is a key contributor to therapeutic failure and post-treatment recurrence. Targeting cell subpopulations responsible for chemoresistance and recurrence seems to be an attractive approach to improve treatment outcome in cancer patients. However, this remains challenging due to the complexity and incomplete characterization of tumor cell subpopulations. The heterogeneity of cells exhibiting stemness-related features, such as self-renewal and chemoresistance, fuels this complexity. Notch signaling is a known regulator of cancer stem cell (CSC) features in colorectal cancer (CRC), though the effects of its heterogenous signaling on CRC cell stemness are only just emerging. In this review, we discuss how Notch ligand-receptor specificity contributes to regulating stemness, self-renewal, chemoresistance and cancer stem cells heterogeneity in CRC.

Rewiring of mitochondrial metabolism in therapy-resistant cancers: permanent and plastic adaptations

Deregulation of tumor cell metabolism is widely recognized as a "hallmark of cancer." Many of the selective pressures encountered by tumor cells, such as exposure to anticancer therapies, navigation of the metastatic cascade, and communication with the tumor microenvironment, can elicit further rewiring of tumor cell metabolism. Furthermore, phenotypic plasticity has been recently appreciated as an emerging "hallmark of cancer." Mitochondria are dynamic organelles and central hubs of metabolism whose roles in cancers have been a major focus of numerous studies. Importantly, therapeutic approaches targeting mitochondria are being developed. Interestingly, both plastic (i.e., reversible) and permanent (i.e., stable) metabolic adaptations have been observed following exposure to anticancer therapeutics. Understanding the plastic or permanent nature of these mechanisms is of crucial importance for devising the initiation, duration, and sequential nature of metabolism-targeting therapies. In this review, we compare permanent and plastic mitochondrial mechanisms driving therapy resistance. We also discuss experimental models of therapy-induced metabolic adaptation, therapeutic implications for targeting permanent and plastic metabolic states, and clinical implications of metabolic adaptations. While the plasticity of metabolic adaptations can make effective therapeutic treatment challenging, understanding the mechanisms behind these plastic phenotypes may lead to promising clinical interventions that will ultimately lead to better overall care for cancer patients.

Association between adjuvant therapy and survival in colorectal cancer patients according to metabolic Warburg-subtypes

PURPOSE

Tumor location and tumor node metastasis (TNM) stage guide treatment decisions in colorectal cancer (CRC) patients. However, patients with the same disease stage do not benefit equally from adjuvant therapy. Hence, there remains an urgent clinical need to identify prognostic and/or predictive biomarker(s) to personalize treatment decisions. In this exploratory study, we investigated whether our previously defined metabolic Warburg-subtypes can predict which CRC patients might derive survival benefit from adjuvant therapy.

METHODS

Information regarding treatment (surgery only: n = 1451; adjuvant radiotherapy: n = 82; or adjuvant chemotherapy: n = 260) and Warburg-subtype (Warburg-low: n = 485, -moderate: n = 641, or -high: n = 667) was available for 1793 CRC patients from the Netherlands Cohort Study (NLCS). Kaplan-Meier curves and Cox regression models were used to investigate survival benefit from adjuvant therapy compared to surgery-only for the different Warburg-subtypes.

RESULTS

Patients with Warburg-moderate CRC (HRCRC-specific 0.64; 95% CI 0.47-0.86, HRoverall 0.61; 95% CI 0.47-0.80), and possibly Warburg-high CRC (HRCRC-specific 0.86; 95% CI 0.65-1.14, HRoverall 0.82; 95% CI 0.64-1.05), had survival benefit from adjuvant therapy. No survival benefit was observed for patients with Warburg-low CRC (HRCRC-specific 1.07; 95% CI 0.76-1.52, HRoverall 0.95; 95% CI 0.70-1.30). There was a significant interaction between Warburg-subtype and adjuvant therapy for CRC-specific survival (p = 0.049) and overall survival (p = 0.035).

CONCLUSION

Our results suggest that Warburg-subtypes may predict survival benefit from adjuvant therapy in CRC patients. A survival benefit from adjuvant therapy was observed for patients with Warburg-moderate and possibly Warburg-high CRC, but not for patients with Warburg-low CRC. Future prospective studies are necessary to validate our findings.

Plant-derived extracts and metabolic modulation in leukemia: a promising approach to overcome treatment resistance

Leukemic cells acquire complex and often multifactorial mechanisms of resistance to treatment, including various metabolic alterations. Although the use of metabolic modulators has been proposed for several decades, their use in clinical practice has not been established. Natural products, the so-called botanical drugs, are capable of regulating tumor metabolism, particularly in hematopoietic tumors, which could partly explain the biological activity attributed to them for a long time. This review addresses the most recent findings relating to metabolic reprogramming-Mainly in the glycolytic pathway and mitochondrial activity-Of leukemic cells and its role in the generation of resistance to conventional treatments, the modulation of the tumor microenvironment, and the evasion of immune response. In turn, it describes how the modulation of metabolism by plant-derived extracts can counteract resistance to chemotherapy in this tumor model and contribute to the activation of the antitumor immune system.

Mechanisms of drug resistance in breast cancer liver metastases: Dilemmas and opportunities

Breast cancer is the leading cause of cancer-related deaths in females worldwide, and the liver is one of the most common sites of distant metastases in breast cancer patients. Patients with breast cancer liver metastases face limited treatment options, and drug resistance is highly prevalent, leading to a poor prognosis and a short survival. Liver metastases respond extremely poorly to immunotherapy and have shown resistance to treatments such as chemotherapy and targeted therapies. Therefore, to develop and to optimize treatment strategies as well as to explore potential therapeutic approaches, it is crucial to understand the mechanisms of drug resistance in breast cancer liver metastases patients. In this review, we summarize recent advances in the research of drug resistance mechanisms in breast cancer liver metastases and discuss their therapeutic potential for improving patient prognoses and outcomes.

Energy Metabolism, Metabolite, and Inflammatory Profiles in Human Ex Vivo Adipose Tissue Are Influenced by Obesity Status, Metabolic Dysfunction, and Treatment Regimes in Patients with Oesophageal Adenocarcinoma

Oesophageal adenocarcinoma (OAC) is a poor prognosis cancer with limited response rates to current treatment modalities and has a strong link to obesity. To better elucidate the role of visceral adiposity in this disease state, a full metabolic profile combined with analysis of secreted pro-inflammatory cytokines, metabolites, and lipid profiles were assessed in human ex vivo adipose tissue explants from obese and non-obese OAC patients. These data were then related to extensive clinical data including obesity status, metabolic dysfunction, previous treatment exposure, and tumour regression grades. Real-time energy metabolism profiles were assessed using the seahorse technology. Adipose explant conditioned media was screened using multiplex ELISA to assess secreted levels of 54 pro-inflammatory mediators. Targeted secreted metabolite and lipid profiles were analysed using Ultra-High-Performance Liquid Chromatography coupled with Mass Spectrometry. Adipose tissue explants and matched clinical data were collected from OAC patients (n = 32). Compared to visceral fat from non-obese patients (n = 16), visceral fat explants from obese OAC patients (n = 16) had significantly elevated oxidative phosphorylation metabolism profiles and an increase in Eotaxin-3, IL-17A, IL-17D, IL-3, MCP-1, and MDC and altered secretions of glutamine associated metabolites. Adipose explants from patients with metabolic dysfunction correlated with increased oxidative phosphorylation metabolism, and increases in IL-5, IL-7, SAA, VEGF-C, triacylglycerides, and metabolites compared with metabolically healthy patients. Adipose explants generated from patients who had previously received neo-adjuvant chemotherapy (n = 14) showed elevated secretions of pro-inflammatory mediators, IL-12p40, IL-1α, IL-22, and TNF-β and a decreased expression of triacylglycerides. Furthermore, decreased secreted levels of triacylglycerides were also observed in the adipose secretome of patients who received the chemotherapy-only regimen FLOT compared with patients who received no neo-adjuvant treatment or chemo-radiotherapy regimen CROSS. For those patients who showed the poorest response to currently available treatments, their adipose tissue was associated with higher glycolytic metabolism compared to patients who had good treatment responses. This study demonstrates that the adipose secretome in OAC patients is enriched with mediators that could prime the tumour microenvironment to aid tumour progression and attenuate responses to conventional cancer treatments, an effect which appears to be augmented by obesity and metabolic dysfunction and exposure to different treatment regimes.

Mitochondrial structure and function adaptation in residual triple negative breast cancer cells surviving chemotherapy treatment

Neoadjuvant chemotherapy (NACT) used for triple negative breast cancer (TNBC) eradicates tumors in ~45% of patients. Unfortunately, TNBC patients with substantial residual cancer burden have poor metastasis free and overall survival rates. We previously demonstrated mitochondrial oxidative phosphorylation (OXPHOS) was elevated and was a unique therapeutic dependency of residual TNBC cells surviving NACT. We sought to investigate the mechanism underlying this enhanced reliance on mitochondrial metabolism. Mitochondria are morphologically plastic organelles that cycle between fission and fusion to maintain mitochondrial integrity and metabolic homeostasis. The functional impact of mitochondrial structure on metabolic output is highly context dependent. Several chemotherapy agents are conventionally used for neoadjuvant treatment of TNBC patients. Upon comparing mitochondrial effects of conventional chemotherapies, we found that DNA-damaging agents increased mitochondrial elongation, mitochondrial content, flux of glucose through the TCA cycle, and OXPHOS, whereas taxanes instead decreased mitochondrial elongation and OXPHOS. The mitochondrial effects of DNA-damaging chemotherapies were dependent on the mitochondrial inner membrane fusion protein optic atrophy 1 (OPA1). Further, we observed heightened OXPHOS, OPA1 protein levels, and mitochondrial elongation in an orthotopic patient-derived xenograft (PDX) model of residual TNBC. Pharmacologic or genetic disruption of mitochondrial fusion and fission resulted in decreased or increased OXPHOS, respectively, revealing longer mitochondria favor oxphos in TNBC cells. Using TNBC cell lines and an in vivo PDX model of residual TNBC, we found that sequential treatment with DNA-damaging chemotherapy, thus inducing mitochondrial fusion and OXPHOS, followed by MYLS22, a specific inhibitor of OPA1, was able to suppress mitochondrial fusion and OXPHOS and significantly inhibit regrowth of residual tumor cells. Our data suggest that TNBC mitochondria can optimize OXPHOS through OPA1-mediated mitochondrial fusion. These findings may provide an opportunity to overcome mitochondrial adaptations of chemoresistant TNBC.

Metabolic reprogramming in colorectal cancer: regulatory networks and therapy

With high prevalence and mortality, together with metabolic reprogramming, colorectal cancer is a leading cause of cancer-related death. Metabolic reprogramming gives tumors the capacity for long-term cell proliferation, making it a distinguishing feature of cancer. Energy and intermediate metabolites produced by metabolic reprogramming fuel the rapid growth of cancer cells. Aberrant metabolic enzyme-mediated tumor metabolism is regulated at multiple levels. Notably, tumor metabolism is affected by nutrient levels, cell interactions, and transcriptional and posttranscriptional regulation. Understanding the crosstalk between metabolic enzymes and colorectal carcinogenesis factors is particularly important to advance research for targeted cancer therapy strategies via the investigation into the aberrant regulation of metabolic pathways. Hence, the abnormal roles and regulation of metabolic enzymes in recent years are reviewed in this paper, which provides an overview of targeted inhibitors for targeting metabolic enzymes in colorectal cancer that have been identified through tumor research or clinical trials.

Global profiling of protein lysine lactylation and potential target modified protein analysis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, often metastasizes to the lungs. The implications of lysine lactylation (Kla), a recently identified histone post-translational modification (PTM), in the pathology of HCC remain unclear. Here, we report the first proteomic survey of this specific modification in HCC (with no metastasis during 3 years of follow-up), normal liver tissues, and lung metastasis samples of HCC. Of the 2045 modification sites detected on 960 proteins, 1438 sites on 772 proteins contained quantitative information. Subsequently, we analyzed the differentially modified proteins among the different groups. Differentially lactylated proteins were found to be involved in several biological processes, including-but not limited to-amino acid metabolism, ribosomal protein synthesis, and fatty acid metabolism. In addition, we identified numerous highly valuable lactate-modified proteins from the literature. Among them, we verified the lactate modification levels of the following two tumor-related proteins and obtained similar results: USP14 and ABCF1. These two modified proteins will be further investigated in our future studies. This paper is the first report on the lactylome of HCC and it provides a reliable foundation for further research on Kla in HCC.

The Influence of Mitochondrial Energy and 1C Metabolism on the Efficacy of Anticancer Drugs: Exploring Potential Mechanisms of Resistance

Mitochondria are the main energy factory in living cells. To rapidly proliferate and metastasize, neoplastic cells increase their energy requirements. Thus, mitochondria become one of the most important organelles for them. Indeed, much research shows the interplay between cancer chemoresistance and altered mitochondrial function. In this review, we focus on the differences in energy metabolism between cancer and normal cells to better understand their resistance and how to develop drugs targeting energy metabolism and nucleotide synthesis. One of the differences between cancer and normal cells is the higher nicotinamide adenine dinucleotide (NAD+) level, a cofactor for the tricarboxylic acid cycle (TCA), which enhances their proliferation and helps cancer cells survive under hypoxic conditions. An important change is a metabolic switch called the Warburg effect. This effect is based on the change of energy harvesting from oxygen-dependent transformation to oxidative phosphorylation (OXPHOS), adapting them to the tumor environment. Another mechanism is the high expression of one-carbon (1C) metabolism enzymes. Again, this allows cancer cells to increase proliferation by producing precursors for the synthesis of nucleotides and amino acids. We reviewed drugs in clinical practice and development targeting NAD+, OXPHOS, and 1C metabolism. Combining novel drugs with conventional antineoplastic agents may prove to be a promising new way of anticancer treatment.

SMAGP regulates doxorubicin sensitivity in triple-negative breast cancer cells via modulating mitochondrial respiration

Doxorubicin-based chemotherapy remains as a major therapeutic approach for patients with triple-negative breast cancer (TNBC). However, insensitivity or resistance to doxorubicin treatment limits the therapeutic efficacy. Mitochondrial respiration plays a critical role in regulating the sensitivity of cancer cells to chemotherapy drugs. Here, we found that small trans-membrane and glycosylated protein (SMAGP) is upregulated in TNBC cells in comparison to normal breast and other subtypes of breast cancer cells. High SMAGP expression is associated with poorer overall survival of TNBC patients. Importantly, loss of SMAGP enhanced the sensitivity of TNBC cells to doxorubicin treatment. Mechanistically, we detected a functional pool of SMAGP in the mitochondria of TNBC cells controlling doxorubicin sensitivity via regulating mitochondrial respiration. Thus, our data suggest that SMAGP acts as a novel regulator of doxorubicin sensitivity in TNBC, identifying SMAGP as a promising therapeutic target for improving the efficacy of doxorubicin-based chemotherapy in TNBC patients.

The Effect of Oxidative Phosphorylation on Cancer Drug Resistance

Recent studies have shown that oxidative phosphorylation (OXPHOS) is a target for the effective attenuation of cancer drug resistance. OXPHOS inhibitors can improve treatment responses to anticancer therapy in certain cancers, such as melanomas, lymphomas, colon cancers, leukemias and pancreatic ductal adenocarcinoma (PDAC). However, the effect of OXPHOS on cancer drug resistance is complex and associated with cell types in the tumor microenvironment (TME). Cancer cells universally promote OXPHOS activity through the activation of various signaling pathways, and this activity is required for resistance to cancer therapy. Resistant cancer cells are prevalent among cancer stem cells (CSCs), for which the main metabolic phenotype is increased OXPHOS. CSCs depend on OXPHOS to survive targeting by anticancer drugs and can be selectively eradicated by OXPHOS inhibitors. In contrast to that in cancer cells, mitochondrial OXPHOS is significantly downregulated in tumor-infiltrating T cells, impairing antitumor immunity. In this review, we summarize novel research showing the effect of OXPHOS on cancer drug resistance, thereby explaining how this metabolic process plays a dual role in cancer progression. We highlight the underlying mechanisms of metabolic reprogramming in cancer cells, as it is vital for discovering new drug targets.

Estrogen-related receptor alpha drives mitochondrial biogenesis and resistance to neoadjuvant chemoradiation in esophageal cancer

Neoadjuvant chemoradiotherapy (nCRT) improves outcomes in resectable esophageal adenocarcinoma (EAC), but acquired resistance precludes long-term efficacy. Here, we delineate these resistance mechanisms. RNA sequencing on matched patient samples obtained pre-and post-neoadjuvant treatment reveal that oxidative phosphorylation was the most upregulated of all biological programs following nCRT. Analysis of patient-derived models confirms that mitochondrial content and oxygen consumption strongly increase in response to nCRT and that ionizing radiation is the causative agent. Bioinformatics identifies estrogen-related receptor alpha (ESRRA) as the transcription factor responsible for reprogramming, and overexpression and silencing of ESRRA functionally confirm that its downstream metabolic rewiring contributes to resistance. Pharmacological inhibition of ESRRA successfully sensitizes EAC organoids and patient-derived xenografts to radiation. In conclusion, we report a profound metabolic rewiring following chemoradiation and demonstrate that its inhibition resensitizes EAC cells to radiation. These findings hold broader relevance for other cancer types treated with radiation as well.

FKBP4 regulates 5-fluorouracil sensitivity in colon cancer by controlling mitochondrial respiration

FKBP4 controls mitochondrial respiration via modulating COA6-mediated biogenesis and activity of mitochondrial complex IV, thereby regulating 5-fluorouracil sensitivity in colon cancer.

Mitochondrial respiration and metabolism play a key role in the pathogenesis and progression of colon adenocarcinoma (COAD). Here, we report a functional pool of FKBP4, a co-chaperone protein, in the mitochondrial intermembrane space (IMS) of colon cancer cells. We found that IMS-localized FKBP4 is essential for the maintenance of mitochondrial respiration, thus contributing to the sensitivity of COAD cells to 5-fluorouracil (5-FU). Mechanistically, FKBP4 interacts with COA6 and controls the assembly of the mitochondrial COA6/SCO1/SCO2 complex, thereby governing COA6-regulated biogenesis and activity of mitochondrial cytochrome c oxidase (complex IV). Thus, our data reveal IMS-localized FKBP4 as a novel regulator of 5-FU sensitivity in COAD, linking mitochondrial respiration to 5-FU sensitivity in COAD.

Drug Resistance in Cancers: A Free Pass for Bullying

The cancer burden continues to grow globally, and drug resistance remains a substantial challenge in cancer therapy. It is well established that cancerous cells with clonal dysplasia generate the same carcinogenic lesions. Tumor cells pass on genetic templates to subsequent generations in evolutionary terms and exhibit drug resistance simply by accumulating genetic alterations. However, recent evidence has implied that tumor cells accumulate genetic alterations by progressively adapting. As a result, intratumor heterogeneity (ITH) is generated due to genetically distinct subclonal populations of cells coexisting. The genetic adaptive mechanisms of action of ITH include activating "cellular plasticity", through which tumor cells create a tumor-supportive microenvironment in which they can proliferate and cause increased damage. These highly plastic cells are located in the tumor microenvironment (TME) and undergo extreme changes to resist therapeutic drugs. Accordingly, the underlying mechanisms involved in drug resistance have been re-evaluated. Herein, we will reveal new themes emerging from initial studies of drug resistance and outline the findings regarding drug resistance from the perspective of the TME; the themes include exosomes, metabolic reprogramming, protein glycosylation and autophagy, and the relates studies aim to provide new targets and strategies for reversing drug resistance in cancers.

Crosstalk of Oxidative Phosphorylation-Related Subtypes, Establishment of a Prognostic Signature and Immune Infiltration Characteristics in Colorectal Adenocarcinoma

Simple Summary

Oxidative phosphorylation (OXPHOS) plays an important role in the progression of colorectal adenocarcinoma (COAD). The aim of our study was to investigate the expression pattern of OXPHOS-related genes (ORGs), and an OXPHOS-related prognostic signature was constructed to classify COAD patients into high-risk and low-risk groups. Then, we analyzed the relationship between risk scores and tumor microenvironment, somatic mutation, and efficacy of immunotherapy and chemotherapy. Additionally, a nomogram was established by combining clinical features and risk scores, and its predictive ability was verified by receiver operating characteristics and calibration curves. Overall, the OXPHOS-related signature can be used as a reliable prognostic predictor of COAD patients.

Abstract

Oxidative phosphorylation (OXPHOS) is an emerging target in cancer therapy. However, the prognostic signature of OXPHOS in colorectal adenocarcinoma (COAD) remains non-existent. We comprehensively investigated the expression pattern of OXPHOS-related genes (ORGs) in COAD from public databases. Based on four ORGs, an OXPHOS-related prognostic signature was established in which COAD patients were assigned different risk scores and classified into two different risk groups. It was observed that the low-risk group had a better prognosis but lower immune activities including immune cells and immune-related function in the tumor microenvironment. Combining with relevant clinical features, a nomogram for clinical application was also established. Receiver operating characteristic (ROC) and calibration curves were constructed to demonstrate the predictive ability of this risk signature. Moreover, a higher risk score was significantly positively correlated with higher tumor mutation burden (TMB) and generally higher gene expression of immune checkpoint, N6-methyladenosine (m6A) RNA methylation regulators and mismatch repair (MMR) related proteins. The results also indicated that the high-risk group was more sensitive to immunotherapy and certain chemotherapy drugs. In conclusion, OXPHOS-related prognostic signature can be utilized to better understand the roles of ORGs and offer new perspectives for clinical prognosis and personalized treatment.

SRGAP2 controls colorectal cancer chemosensitivity via regulation of mitochondrial complex I activity

Mitochondrial respiration and metabolism play an important role in the occurrence and development of colorectal cancer (CRC). In this study, we identified a functional pool of SLIT-ROBO Rho GTPase-activating protein 2 (SRGAP2) in the mitochondria of CRC cells as an important regulator of CRC chemosensitivity. We found that SRGAP2 levels were increased in CRC cells in comparison to normal colorectal cells. Loss of mitochondrial SRGAP2 led to significant decrease in mitochondrial respiration and strongly sensitized the CRC cells to chemotherapy drugs. Mechanistically, SRGAP2 physically interacts with mitochondrial complex I and positively modulates its activity. In particular, chemosensitization upon SRGAP2 loss was phenocopied by the treatment of complex I inhibitor. Thus, our results demonstrate that SRGAP2 functions as a key regulator of CRC chemosensitivity, identifying SRGAP2 as a promising therapeutic target to enhance the efficacy of chemotherapy in CRC.

SIRT1 regulated hexokinase-2 promoting glycolysis is involved in hydroquinone-enhanced malignant progression in human lymphoblastoid TK6 cells

Reprogramming of cellular metabolism is a vital event during tumorigenesis. The role of glycolysis in malignant progression promoted by hydroquinone (HQ), one of the metabolic products of benzene, remains to be understood. Recently, we reported the overexpression of sirtuin 1 (SIRT1) in HQ-enhanced malignant progression of TK6 cells and hypothesized that SIRT1 might contribute to glycolysis and favor tumorigenesis. Our data showed that acute exposure of TK6 cells to HQ for 48 h inhibited glycolysis, as indicated by reduction in glucose consumption, lactate production, hexokinase activity, and the expression of SIRT1 and glycolytic enzymes, including HIF-1α, hexokinase-2 (HK-2), ENO-1, glucose transporter 1 (Glut-1), and lactic dehydrogenase A (LDHA). Knockdown of SIRT1 or inhibition of glycolysis using the glycolytic inhibitor 2-deoxy-D-glucose (2-DG) downregulated the levels of SIRT1 and glycolytic enzymes and significantly enhanced HQ-induced cell apoptosis, although knockdown of SIRT1 or 2-DG alone had little effect on apoptosis. Furthermore, immunofluorescence and Co-IP assays demonstrated that SIRT1 regulated the expression of HK-2, and HQ treatment caused a decrease in SIRT1 and HK-2 binding to mitochondria. Importantly, we found that glycolysis was promoted with increasing HQ treatment weeks. Long-term HQ exposure increased the expression of SIRT1 and several glycolytic enzymes and promoted malignant cell progression. Moreover, compared with the PBS group, glucose consumption and lactate production increased after 10 weeks of HQ exposure, and the protein levels of SIRT1 and HK-2 were increased after 15 weeks of HQ exposure, while those of Glut-1, ENO-1, and LDHA were elevated. In addition, SIRT1 knockdown HQ 19 cells exhibited decreased lactate production, glucose consumption, glycolytic enzymes expression, cell growth, and tumor formation in nude mice. Our findings identify the high expression of SIRT1 as a strong oncogenic driver that positively regulates HK-2 and promotes glycolysis in HQ-accelerated malignant progression of TK6 cells.

A novel prognostic model predicts overall survival in colon cancer based on RNA splicing regulation gene expression

Colon cancer is the third most common cancer and the second leading cause of cancer‐related death worldwide. Dysregulated RNA splicing factors have been reported to be associated with tumorigenesis and development in colon cancer. In this study, we interrogated clinical and RNA expression data of colon cancer patients from The Cancer Genome Atlas (TCGA) dataset and the Gene Expression Omnibus (GEO) database. Genes regulating RNA splicing correlated with survival in colon cancer were identified and a risk score model was constructed using Cox regression analyses. In the risk model, RNA splicing factor peroxisome proliferator‐activated receptor‐γ coactivator‐1α (PPARGC1) is correlated with a good survival outcome, whereas Cdc2‐like kinase 1(CLK1), CLK2, and A‐kinase anchor protein 8‐like (AKAP8L) with a bad survival outcome. The risk model has a good performance for clinical prognostic prediction both in the TCGA cohort and the other two validation cohorts. In the tumor microenvironment (TME) analysis, the immune score was higher in the low‐risk group, and TME‐related pathway gene expression was also higher in low‐risk group. We further verified the mRNA and protein expression levels of these four genes in the adjacent nontumor, tumor, and liver metastasis tissues of colon cancer patients, which were consistent with bioinformatics analysis. In addition, knockdown of AKAP8L can suppress the proliferation and migration of colon cancer cells. Animal studies have also shown that AKAP8L knockdown can inhibit tumor growth in colon cancer in vivo. We established a prognostic risk model for colon cancer based on genes related to RNA splicing regulation and uncovered the role of AKAP8L in promoting colon cancer progression.

Identification of shared and disease-specific host gene-microbiome associations across human diseases using multi-omic integration

While gut microbiome and host gene regulation independently contribute to gastrointestinal disorders, it is unclear how the two may interact to influence host pathophysiology. Here we developed a machine learning-based framework to jointly analyse paired host transcriptomic (n = 208) and gut microbiome (n = 208) profiles from colonic mucosal samples of patients with colorectal cancer, inflammatory bowel disease and irritable bowel syndrome. We identified associations between gut microbes and host genes that depict shared as well as disease-specific patterns. We found that a common set of host genes and pathways implicated in gastrointestinal inflammation, gut barrier protection and energy metabolism are associated with disease-specific gut microbes. Additionally, we also found that mucosal gut microbes that have been implicated in all three diseases, such as Streptococcus, are associated with different host pathways in each disease, suggesting that similar microbes can affect host pathophysiology in a disease-specific manner through regulation of different host genes. Our framework can be applied to other diseases for the identification of host gene-microbiome associations that may influence disease outcomes.

Synergistic Tumor Inhibition via Energy Elimination by Repurposing Penfluridol and 2-Deoxy-D-Glucose in Lung Cancer

Simple Summary

Drug repurposing has been effective for discovering novel treatments for cancer. The antipsychotic agent penfluridol was reported to suppress lung cancer growth via ATP energy deprivation. The aim of our study was to investigate how penfluridol influences energy metabolism in lung cancer cells. We observed that penfluridol inhibited mitochondrial oxidative phosphorylation (OXPHOS), but induced glycolysis to compensate for the loss of ATP caused by suppression of mitochondrial OXPHOS. We also confirmed that inhibition of glycolysis by 2-deoxy-D-glucose (2DG) significantly augmented the antitumor effects caused by penfluridol in vitro and in vivo. Our studies provide novel insights into repurposing penfluridol combined with 2-DG for lung cancer treatment.

Abstract

Energy metabolism is the basis for cell growth, and cancer cells in particular, are more energy-dependent cells because of rapid cell proliferation. Previously, we found that penfluridol, an antipsychotic drug, has the ability to trigger cell growth inhibition of lung cancer cells via inducing ATP energy deprivation. The toxic effect of penfluridol is related to energy metabolism, but the underlying mechanisms remain unclear. Herein, we discovered that treatment of A549 and HCC827 lung cancer cells with penfluridol caused a decrease in the total amount of ATP, especially in A549 cells. An Agilent Seahorse ATP real-time rate assay revealed that ATP production rates from mitochondrial respiration and glycolysis were, respectively, decreased and increased after penfluridol treatment. Moreover, the amount and membrane integrity of mitochondria decreased, but glycolysis-related proteins increased after penfluridol treatment. Furthermore, we observed that suppression of glycolysis by reducing glucose supplementation or using 2-deoxy-D-glucose (2DG) synergistically enhanced the inhibitory effect of penfluridol on cancer cell growth and the total amount of mitochondria. A mechanistic study showed that the penfluridol-mediated energy reduction was due to inhibition of critical regulators of mitochondrial biogenesis, the sirtuin 1 (SIRT1)/peroxisome-proliferator-activated receptor co-activator-1α (PGC-1α) axis. Upregulation of the SIRT1/PGC-1α axis reversed the inhibitory effect of penfluridol on mitochondrial biogenesis and cell viability. Clinical lung cancer samples revealed a positive correlation between PGC-1α (PPARGC1A) and SIRT1 expression. In an orthotopic lung cancer mouse model, the anticancer activities of penfluridol, including growth and metastasis inhibition, were also enhanced by combined treatment with 2DG. Our study results strongly support that a combination of repurposing penfluridol and a glycolysis inhibitor would be a good strategy for enhancing the anticancer activities of penfluridol in lung cancer.

Inducing respiratory complex I impairment elicits an increase in PGC1α in ovarian cancer

Anticancer strategies aimed at inhibiting Complex I of the mitochondrial respiratory chain are increasingly being attempted in solid tumors, as functional oxidative phosphorylation is vital for cancer cells. Using ovarian cancer as a model, we show that a compensatory response to an energy crisis induced by Complex I genetic ablation or pharmacological inhibition is an increase in the mitochondrial biogenesis master regulator PGC1α, a pleiotropic coactivator of transcription regulating diverse biological processes within the cell. We associate this compensatory response to the increase in PGC1α target gene expression, setting the basis for the comprehension of the molecular pathways triggered by Complex I inhibition that may need attention as drawbacks before these approaches are implemented in ovarian cancer care.

Mitochondrial Function Differences between Tumor Tissue of Human Metastatic and Premetastatic CRC

Simple Summary

Metastasis is an important cause of death from colorectal cancer (CRC). Mitochondria, which are important organelles of cells, play a key role in the metastatic transformation of cancer cells. We aimed to evaluate the adaptations associated with mitochondrial function in tumor tissues from advanced stages of human CRC and whether they could ultimately be used as a therapeutic target in metastatic CRC. We have compared the mitochondrial functionality parameters in tumor tissue samples and the normal adjacent tissue of advanced CRC patients with no radio- or chemotherapy treatment before surgery. Notable differences in mitochondrial functionality were detected between the samples of adjacent tissue versus tumor tissue from metastatic CRC patients. These findings suggest a shift in the mitochondrial function profile occurring in tumor tissue once the metastatic stage has been reached. These changes contribute to promote and maintain the metastatic phenotype, with evidence of mitochondrial function impairment in tumor tissue in the metastatic stage samples.

Abstract

Most colorectal cancer (CRC) patients die as a consequence of metastasis. Mitochondrial dysfunction could enhance cancer development and metastatic progression. We aimed to evaluate the adaptations associated with mitochondrial function in tumor tissues from stages III and IV of human CRC and whether they could ultimately be used as a therapeutic target in metastatic colorectal cancer (mCRC). We analyzed the protein levels by Western blotting and the enzymatic activities of proteins involved in mitochondrial function, as well as the amount of mitochondrial DNA (mtDNA), by real-time PCR, analyzing samples of non-tumor adjacent tissue and tumor tissue from stages III and IV CRC patients without radio- or chemotherapy treatment prior to surgery. Our data indicate that the tumor tissue of pre-metastatic stage III CRC exhibited an oxidant metabolic profile very similar to the samples of non-tumor adjacent tissue of both stages. Notable differences in the protein expression levels of ATPase, IDH2, LDHA, and SIRT1, as well as mtDNA amount, were detected between the samples of non-tumor adjacent tissue and tumor tissue from metastatic CRC patients. These findings suggest a shift in the oxidative metabolic profile that takes place in the tumor tissue once the metastatic stage has been reached. Tumor tissue oxidative metabolism contributes to promote and maintain the metastatic phenotype, with evidence of mitochondrial function impairment in stage IV tumor tissue.

Melatonin: Regulation of Prion Protein Phase Separation in Cancer Multidrug Resistance

The unique ability to adapt and thrive in inhospitable, stressful tumor microenvironments (TME) also renders cancer cells resistant to traditional chemotherapeutic treatments and/or novel pharmaceuticals. Cancer cells exhibit extensive metabolic alterations involving hypoxia, accelerated glycolysis, oxidative stress, and increased extracellular ATP that may activate ancient, conserved prion adaptive response strategies that exacerbate multidrug resistance (MDR) by exploiting cellular stress to increase cancer metastatic potential and stemness, balance proliferation and differentiation, and amplify resistance to apoptosis. The regulation of prions in MDR is further complicated by important, putative physiological functions of ligand-binding and signal transduction. Melatonin is capable of both enhancing physiological functions and inhibiting oncogenic properties of prion proteins. Through regulation of phase separation of the prion N-terminal domain which targets and interacts with lipid rafts, melatonin may prevent conformational changes that can result in aggregation and/or conversion to pathological, infectious isoforms. As a cancer therapy adjuvant, melatonin could modulate TME oxidative stress levels and hypoxia, reverse pH gradient changes, reduce lipid peroxidation, and protect lipid raft compositions to suppress prion-mediated, non-Mendelian, heritable, but often reversible epigenetic adaptations that facilitate cancer heterogeneity, stemness, metastasis, and drug resistance. This review examines some of the mechanisms that may balance physiological and pathological effects of prions and prion-like proteins achieved through the synergistic use of melatonin to ameliorate MDR, which remains a challenge in cancer treatment.

Reversing tozasertib resistance in glioma through inhibition of pyruvate dehydrogenase kinases

Acquired resistance to conventional chemotherapeutic agents limits their effectiveness and can cause cancer treatment to fail. Because enzymes in the aurora kinase family are vital regulators of several mitotic events, we reasoned that targeting these kinases with tozasertib, a pan-aurora kinase inhibitor, would not only cause cytokinesis defects, but also induce cell death in high-grade pediatric and adult glioma cell lines. We found that tozasertib induced cell cycle arrest, increased mitochondrial permeability and reactive oxygen species generation, inhibited cell growth and migration, and promoted cellular senescence and pro-apoptotic activity. However, sustained exposure to tozasertib at clinically relevant concentrations conferred resistance, which led us to examine the mechanistic basis for the emergence of drug resistance. RNA-sequence analysis revealed a significant upregulation of the gene encoding pyruvate dehydrogenase kinase isoenzyme 4 (PDK4), a pyruvate dehydrogenase (PDH) inhibitory kinase that plays a crucial role in the control of metabolic flexibility under various physiological conditions. Upregulation of PDK1, PDK2, PDK3, or PDK4 protein levels was positively correlated with tozasertib-induced resistance through inhibition of PDH activity. Tozasertib-resistant cells exhibited increased mitochondrial mass as measured by 10-N-nonyl-Acridine Orange. Inhibition of PDK with dichloroacetate resulted in increased mitochondrial permeability and cell death in tozasertib-resistant glioma cell lines. Based on these results, we believe that PDK is a selective target for the tozasertib resistance phenotype and should be considered for further preclinical evaluations.

Targeting the Interplay between Cancer Metabolic Reprogramming and Cell Death Pathways as a Viable Therapeutic Path

In cancer cells, metabolic adaptations are often observed in terms of nutrient absorption, biosynthesis of macromolecules, and production of energy necessary to meet the needs of the tumor cell such as uncontrolled proliferation, dissemination, and acquisition of resistance to death processes induced by both unfavorable environmental conditions and therapeutic drugs. Many oncogenes and tumor suppressor genes have a significant effect on cellular metabolism, as there is a close relationship between the pathways activated by these genes and the various metabolic options. The metabolic adaptations observed in cancer cells not only promote their proliferation and invasion, but also their survival by inducing intrinsic and acquired resistance to various anticancer agents and to various forms of cell death, such as apoptosis, necroptosis, autophagy, and ferroptosis. In this review we analyze the main metabolic differences between cancer and non-cancer cells and how these can affect the various cell death pathways, effectively determining the susceptibility of cancer cells to therapy-induced death. Targeting the metabolic peculiarities of cancer could represent in the near future an innovative therapeutic strategy for the treatment of those tumors whose metabolic characteristics are known.

Impact of cancer metabolism on therapy resistance - Clinical implications

Despite an increasing arsenal of anticancer therapies, many patients continue to have poor outcomes due to the therapeutic failures and tumor relapses. Indeed, the clinical efficacy of anticancer therapies is markedly limited by intrinsic and/or acquired resistance mechanisms that can occur in any tumor type and with any treatment. Thus, there is an urgent clinical need to implement fundamental changes in the tumor treatment paradigm by the development of new experimental strategies that can help to predict the occurrence of clinical drug resistance and to identify alternative therapeutic options. Apart from mutation-driven resistance mechanisms, tumor microenvironment (TME) conditions generate an intratumoral phenotypic heterogeneity that supports disease progression and dismal outcomes. Tumor cell metabolism is a prototypical example of dynamic, heterogeneous, and adaptive phenotypic trait, resulting from the combination of intrinsic [(epi)genetic changes, tissue of origin and differentiation dependency] and extrinsic (oxygen and nutrient availability, metabolic interactions within the TME) factors, enabling cancer cells to survive, metastasize and develop resistance to anticancer therapies. In this review, we summarize the current knowledge regarding metabolism-based mechanisms conferring adaptive resistance to chemo-, radio-and immunotherapies as well as targeted therapies. Furthermore, we report the role of TME-mediated intratumoral metabolic heterogeneity in therapy resistance and how adaptations in amino acid, glucose, and lipid metabolism support the growth of therapy-resistant cancers and/or cellular subpopulations. We also report the intricate interplay between tumor signaling and metabolic pathways in cancer cells and discuss how manipulating key metabolic enzymes and/or providing dietary changes may help to eradicate relapse-sustaining cancer cells. Finally, in the current era of personalized medicine, we describe the strategies that may be applied to implement metabolic profiling for tumor imaging, biomarker identification, selection of tailored treatments and monitoring therapy response during the clinical management of cancer patients.

DIA-based Proteomics Identifies IDH2 as a Targetable Regulator of Acquired Drug Resistance in Chronic Myeloid Leukemia

Drug resistance is a critical obstacle to effective treatment in patients with chronic myeloid leukemia (CML). To understand the underlying resistance mechanisms in response to imatinib (IMA) and adriamycin (ADR), the parental K562 cells were treated with low doses of IMA or ADR for two months to generate derivative cells with mild, intermediate and severe resistance to the drugs as defined by their increasing resistance index (RI). PulseDIA-based quantitative proteomics was then employed to reveal the proteome changes in these resistant cells. In total, 7082 proteotypic proteins from 98,232 peptides were identified and quantified from the dataset using four DIA software tools including OpenSWATH, Spectronaut, DIA-NN, and EncyclopeDIA. Sirtuin Signaling Pathway was found to be significantly enriched in both ADR- and IMA-resistant K562 cells. In particular, IDH2 was identified as a potential drug target correlated with the drug resistance phenotype, and its inhibition by the antagonist AGI-6780 reversed the acquired resistance in K562 cells to either ADR or IMA. Together, our study has implicated IDH2 as a potential target that can be therapeutically leveraged to alleviate the drug resistance in K562 cells when treated with IMA and ADR.

MCP mediated active targeting calcium phosphate hybrid nanoparticles for the treatment of orthotopic drug-resistant colon cancer

BACKGROUND

Colon cancer is a most common malignant cancer in digestive system, and it is prone to develop resistance to the commonly used chemotherapy drugs, leading to local recurrence and metastasis. Paris saponin VII (PSVII) could not only inhibit the proliferation of colon cancer cells but also effectively induce apoptosis of drug-resistant colon cancer cells and reduce the metastasis of drug-resistant colon cancer cells as well. However, PSVII was insoluble in water and fat. It displayed no selective distribution in body and could cause severe hemolysis. Herein, colon cancer targeting calcium phosphate nanoparticles were developed to carry PSVII to treat drug-resistant colon cancer.

RESULTS

PSVII carboxymethyl-β-cyclodextrin inclusion compound was successfully encapsulated in colon cancer targeting calcium phosphate nanoparticles (PSVII@MCP-CaP) by using modified citrus pectin as stabilizer agent and colon cancer cell targeting moiety. PSVII@MCP-CaP significantly reduced the hemolysis of PSVII. Moreover, by specific accumulating in orthotopic drug-resistant colon cancer tissue, PSVII@MCP-CaP markedly inhibited the growth of orthotopic drug-resistant colon cancer in nude mice. PSVII@MCP-CaP promoted the apoptosis of drug-resistant colon cancer cells through mitochondria-mediated apoptosis pathway. Moreover, PSVII@MCP-CaP significantly inhibited the invasion and migration of drug-resistant colon cancer cells by increasing E-cadherin protein expression and reducing N-cadherin and MMP-9 protein expression.

CONCLUSION

PSVII@MCP-CaP has great potential in the treatment of drug-resistant colon cancer. This study also explores a new method to prepare active targeting calcium phosphate nanoparticles loaded with a fat and water insoluble compound in water.

Steroid receptor RNA activator gene footprint in the progression and drug resistance of colorectal cancer through oxidative phosphorylation pathway

BACKGROUND

The steroid receptor RNA activator 1 (SRA1) gene is involved in the progression of various cancers via different molecular mechanisms mediated by long non-coding RNA SRA (lncRNA SRA). This study aimed to evaluate the lncRNA SRA effect on the tumor progression of colorectal cancer (CRC).

METHODS

SRA1 expression was assessed in the cancer genome atlas datasets, CRC cell lines, and tumor specimens. Meta-analysis and gene co-expression network analysis were performed to identify pathways related to SRA1. RNA interference and cell treatment were utilized to examine the role of SRA1 expression in HT-29 and Caco-2 cell lines. Also, the effect of SRA1 expression was investigated on drug resistance, clinical parameters, and mutations in CRC samples.

RESULTS

The SRA1 transcripts, especially lncRNA SRA, were dysregulated in CRC tissue samples compared with normal tissue samples. Furthermore, SRA1 depletion decreased colony formation and proliferation while induced apoptosis in HT-29 and Caco-2 cells. In silico analyses indicated that SRA1 level was correlated with expression levels of oxidative phosphorylation (OXPHOS) genes. LncRNA SRA expression increased in response to the increased oxidative capacity, and when lncRNA SRA was knocked down, the expression level of OXPHOS pathway genes, including NDUFB5 and ATP5F1B, was changed. Also, KRAS-mutant samples had the highest SRA1 expression level.

CONCLUSIONS

LncRNA SRA could function as an oncogene through the OXPHOS pathway in CRC, and serve as a potential biomarker for identifying CRC subtype with KRAS mutations. The findings suggest that lncRNA SRA might be a therapeutic target to inhibit cell proliferation in CRC.

Regulation of signal transduction pathways in colorectal cancer: implications for therapeutic resistance

Resistance to anti-cancer treatments is a critical and widespread health issue that has brought serious impacts on lives, the economy and public policies. Mounting research has suggested that a selected spectrum of patients with advanced colorectal cancer (CRC) tend to respond poorly to both chemotherapeutic and targeted therapeutic regimens. Drug resistance in tumours can occur in an intrinsic or acquired manner, rendering cancer cells insensitive to the treatment of anti-cancer therapies. Multiple factors have been associated with drug resistance. The most well-established factors are the emergence of cancer stem cell-like properties and overexpression of ABC transporters that mediate drug efflux. Besides, there is emerging evidence that signalling pathways that modulate cell survival and drug metabolism play major roles in the maintenance of multidrug resistance in CRC. This article reviews drug resistance in CRC as a result of alterations in the MAPK, PI3K/PKB, Wnt/β-catenin and Notch pathways.