Inhibition Of Oxidative Phosphorylation Research Articles

Inhibition of Carbohydrate Metabolism Potentiated by the Therapeutic Effects of Oxidative Phosphorylation Inhibitors in Colon Cancer Cells.

Cancer cells undergo a significant level of "metabolic reprogramming" or "remodeling" to ensure an adequate supply of ATP and "building blocks" for cell survival and to facilitate accelerated proliferation. Cancer cells preferentially use glycolysis for ATP production (the Warburg effect); however, cancer cells, including colorectal cancer (CRC) cells, also depend on oxidative phosphorylation (OXPHOS) for ATP production, a finding that suggests that both glycolysis and OXPHOS play significant roles in facilitating cancer progression and proliferation. Our prior studies identified a semisynthetic isoflavonoid, DBI-1, that served as an AMPK activator targeting mitochondrial complex I. Furthermore, DBI-1 and a glucose transporter 1 (GLUT1) inhibitor, BAY-876, synergistically inhibited CRC cell growth in vitro and in vivo. We now report a study of the structure-activity relationships (SARs) in the isoflavonoid family in which we identified a new DBI-1 analog, namely, DBI-2, with promising properties. Here, we aimed to explore the antitumor mechanisms of DBIs and to develop new combination strategies by targeting both glycolysis and OXPHOS. We identified DBI-2 as a novel AMPK activator using an AMPK phosphorylation assay as a readout. DBI-2 inhibited mitochondrial complex I in the Seahorse assays. We performed proliferation and Western blotting assays and conducted studies of apoptosis, necrosis, and autophagy to corroborate the synergistic effects of DBI-2 and BAY-876 on CRC cells in vitro. We hypothesized that restricting the carbohydrate uptake with a KD would mimic the effects of GLUT1 inhibitors, and we found that a ketogenic diet significantly enhanced the therapeutic efficacy of DBI-2 in CRC xenograft mouse models, an outcome that suggested a potentially new approach for combination cancer therapy.

Abstract 5972: Therapeutic modulation of rock overcomes metabolic adaption to oxphos inhibition and suppresses tumor growth

Abstract Lung cancer is the top cause of cancer mortality. Despite recent advances, the majority of patients with lung cancer still lack effective therapeutic options, underscoring the dire need for additional treatment approaches. Genomic studies have identified frequent mutations in subunits of the SWI/SNF chromatin remodeling complex including SMARCA4 and ARID1A in non-small cell lung cancer with a frequency of up to 33% in advanced stage disease, making it the most frequently mutated complex in lung cancer. Previous work in our lab, as well as others, have identified a metabolic vulnerability in targeting oxidative phosphorylation (OXPHOS) in SMARCA4-mutant lung cancer. However, OXPHOS inhibitors are still not approved to treat cancer due to modest efficacy and adverse effects. This strongly suggests that novel, efficacious and tolerated agents that synergize with OXPHOS inhibition are urgently needed. To this end, we undertook a functional genomics screen by utilizing a focused CRISPR-Cas9 library targeting genes with available FDA approved therapeutics in genetically defined lung cancer cell lines. Importantly, we utilized low doses of the OXPHOS inhibitor IACS-10759 that are known to be well tolerated in patients. Among our top validated hits was ROCK1/2 kinases and we demonstrate that Belumasudil, a clinically approved ROCK inhibitor with a robust safety and tolerability profile, displays a synergistic combination with IACS-10759. Furthermore, low doses of IACS-10759 synergized with ROCK inhibition in vivo eliciting marked tumor growth inhibition. Mechanistically, we showed that the combination of Belumasudil and IACS-10759 induced a profound energetic stress. This was primarily due to ROCK inhibition-mediated suppression of the normally observed adaptive increase in glycolysis upon OXPHOS inhibition. Steady-state metabolomics and C13-glucose isotope tracing confirmed downregulation of multiple glycolytic metabolites and reduced glycolytic flux by the combination of ROCK inhibition and IACS-10759 and was associated with severe reduction in glucose uptake. In summary, our study identified a key role of ROCK kinases in metabolic adaptation of cancer cells and provides a strong rationale for pursuing ROCK inhibitors as novel combination agents with OXPHOS inhibition and lay the foundation for future clinical investigation in genetically defined subtypes of lung cancer. Citation Format: Nicholas Blazanin, Xiaobing Liang, Iqbal Mahmud, Eiru Kim, Lin Tan, Nazanin Esmaeili Anvar, Waikin Chan, Min Jin Ha, Rosalba Minelli, Michael Peoples, Philip Lorenzi, Travar Hart, Yonathan Lissanu, Nicholas Blazanin. Therapeutic modulation of rock overcomes metabolic adaption to oxphos inhibition and suppresses tumor growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5972.

Abstract 7052: p53 underpins a dependence on oxidative phosphorylation in glycolysis-competent colorectal cancer

Abstract The use of mitochondrial inhibitors to target oxidative phosphorylation (OXPHOS) in cancer treatment presents a challenge due to dose-limiting toxicities. Moreover, while glycolysis-deficient cancers are vulnerable to OXPHOS inhibition in preclinical models, the full extent of phenotypical and mechanistic consequences of inhibiting OXPHOS in cancers capable of glycolysis is not yet well understood. Our results presented here offer promising insights into potential therapeutic gains from combining p53 restoration strategies with OXPHOS inhibitors, even when applied to glycolysis-competent CRC cells. Treatment with mitochondrial complex I inhibitors did not cause energy stress in CRC cells capable of glycolysis. It does, however, induce DNA replication stress, apparent through an observed cell cycle arrest at the S phase, enrichment of the G2/M DNA-damage checkpoint regulation pathway, and replication fork slowdown. Intriguingly, CRC cells harboring wildtype p53 exhibited more severe replication stress than those carrying mutant p53. Furthermore, siRNA knockdown of p53 attenuates replication stress and reduces cell cycle arrest, underlining the important role of p53 in CRC cell responses to OXPHOS inhibition. Our targeted metabolomics analysis reveals that OXPHOS inhibition results in reductions in the purine nucleotides, adenine monophosphate (AMP) and guanine monophosphate (GMP), as well as the pyrimidine nucleotide, uridine monophosphate (UMP), in CRC cells, regardless of their p53 mutational status. By supplementing cell culture mediums with the purine nucleobases adenine and guanine, and the pyrimidine nucleoside uridine, we observed a partial reversal of the replication fork slowdown and reductions in cell viability. This suggests nucleotide deficiencies are involved in the induction of DNA replication stress caused by OXPHOS inhibition. The nucleotide deficiencies were associated with a decrease in the nucleobase precursor aspartate. By adding aspartate at a supraphysiological concentration, to overcome the low expression of the excitatory amino acid transporter 1 required for cellular import of aspartate, we were able to restore the levels of nucleotides. Collectively, our findings suggest broader potential cancer treatment paradigms via OXPHOS targeting, extending beyond glycolysis-deficient cancers. Our data uncovers that CRC cells, which commonly exhibit the glycolytic phenotype, are susceptible to OXPHOS inhibition, with those carrying wildtype p53 showing heightened sensitivity. Therefore, p53 status could serve as a biomarker for predicting CRC responses to OXPHOS inhibitors. Moreover, our findings suggest that combined strategies of restoring p53 function, using small molecules such as APR-246, might enable reduced dosage of OXPHOS inhibitors in CRC treatment, thereby mitigating their dose-limiting toxicities. Citation Format: Xiao Hong Zhao, Man Man Han, Qian Qian Yan, Yi Meng Yue, Kai Hong Ye, Yuan Yuan Zhang, Liu Teng, Liang Xu, Xiao Jing Shi, Ting La, Yu Chen Feng, Ran Xu, Vinod K. Narayana, David P. De Souza, Tao Liu, Mark Baker, Rick F. Thorne, Xu Dong Zhang, Song Chen, Lei Jin. p53 underpins a dependence on oxidative phosphorylation in glycolysis-competent colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7052.

Abstract 1797: Investigating the significance of OXPHOS activity in non-small cell lung cancer brain metastases

Abstract Background: Brain metastasis is a common and devastating occurrence for patients with non-small cell lung cancer (NSCLC). NSCLC patients with brain metastases have a poor median overall survival of 2-3 months, highlighting the urgency for novel treatment strategies. One approach to understanding and potentially targeting metastasis is via cancer metabolism. During the metastatic cascade, cancer cells must survive and adapt to the differential nutrient environments they encounter, including the brain. The blood brain barrier limits the availability of many metabolites, leading metastatic cells to alter their nutrient use to survive. RNA sequencing analyses of NSCLC brain metastases suggest that increased oxidative phosphorylation (OXPHOS) may be one such metabolic adaptation in the brain. The aim of this study was to determine the necessity of OXPHOS activity as a metabolic adaptation for NSCLC cells to proliferate in the unique metabolic environment of the brain. Materials and Methods: NSCLC cells were cultured in media mimicking the metabolic environments of the brain and blood. Expression of mitochondrial markers were evaluated by immunoblot in cells cultured across media conditions. The effects of the OXPHOS inhibitor IACS-010759 were assessed by cell growth as well as stable isotope tracing with [U-13C] glucose. Patient derived xenografts (PDXs) were derived from a cohort of patients with NSCLC who underwent stable isotope tracing with [U-13C] glucose. Mice bearing subcutaneously implanted PDXs were treated daily with 5mg/kg IACS-010759 and metastatic burden was measured by flow cytometry and histology. Results: Tracing studies in patients revealed that high enrichment in OXPHOS-related metabolites in the primary tumor correlated with worse patient outcomes. Compared with other media conditions, cells cultured in media replicating the metabolic environment of the brain have increased expression of mitochondrial proteins, increased 13C glucose labeling in the TCA cycle, and a larger reduction in proliferation with IACS-010759 treatment. Using our PDX models, inhibition of OXPHOS with IACS-010759 had little effect on subcutaneous tumor growth but reduced metastasis in the lung and the brain. Conclusions: OXPHOS activity may be enhanced in NSCLC brain metastases due to the unique metabolic environment of the brain. This elevated OXPHOS activity may be necessary for NSCLC brain metastasis growth, as OXPHOS inhibition reduced metastasis in the brain. NSCLC cells may undergo mitochondrial biogenesis to support survival in this unique metabolic environment, and this may represent an area of therapeutic vulnerability for brain metastases. Citation Format: Nia G. Hammond, Massar Alsamraae, Mayher Kaur, Rachel Zuckerman, Brianna Chang, Robert Cameron, Aaron Dyas, Brandon Faubert. Investigating the significance of OXPHOS activity in non-small cell lung cancer brain metastases [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1797.

Abstract 851: Uncovering a novel role of succinate metabolism in tregulatory cells of aged epithelial ovarian cancer mice

Abstract Epithelial Ovarian Cancer (EOC), the most fatal gynecologic cancer is a disease of older women, with median age of 63 years at diagnosis. Reduced naive T cell generation and a rise in immunosuppressive regulatory T (Treg) cells are hallmarks of aging, which are strongly correlated with advanced cancer stage. Aging also alters host and cellular metabolism, which can influence Treg number and function. Although metabolic alterations are known to impact ant-tumor immune response, the relationship between age-related metabolic dysfunction and immune cells is not fully understood. We utilized young (2 months) and old (18 months) female C57/B6 mice, and were injected intraperitoneally with 5 × 106 mouse epithelial ovarian cancer ID8p53-/− cells. Old mice with EOC showed decreased survival compared to young mice (median survival 49 vs 65 days). Old mice with EOC presented with decreased CD4+ and CD8+ T cells, but a significant increase in CD4+CD25+FoxP3+ Treg cells in tumor micro environment (TME) and in blood. The Tregs from old mice displayed enhanced expression of IL10 and TGFβ, which corelated with their increased suppression of CD4 and CD8 T cells compared to Tregs isolated from young EOC mice. The CD4+ and CD8+ T cells also displayed decreased effector makers including CD4+IFNγ, CD8+IFNγ and CD8+ Granzyme B, compared to young EOC mice in TME and in blood. The tumor promoting role of Treg was validated by depleting Tregs using anti-CD25 antibody which resulted in decreased tumor burden and improved overall survival, of both young and old mice, more significantly in old EOC mice. Tregs from old mice with EOC displayed enhanced metabolic activity, reflected in increased oxidative phosphorylation (OXPHOS) compared to young EOC mice. Further, on inhibition of OXPHOS, the Tregs from old mice showed decreased expression of immunosuppressive markers Foxp3 and IL10. Targeted metabolomics of TCA cycle in the Tregs, revealed a 5-fold increase in succinate levels in old EOC Tregs compared to young. Succinate treatment enhanced the immunosuppressive Treg function along with an increase in levels of IL10 and TGFβ, while inhibition of succinate synthesis reversed the increase in FOXP3, IL10 and TGFβ. We identified fibroblast growth factor 21 (FGF-21), a hormone essential for T cell development, to be significantly decreased in ascites and plasma, of old mice. Supplementing FGF21 decreased Treg survival, number, and suppressive ability, resulting in increased CD4+ and CD8+ cells in aged EOC mice. FGF21 treatment decreased OXPHOS and succinate levels in aged Tregs. Overall, our observations indicate Tregs to be vital in driving aggressive EOC in old mice. The hyper-suppressive Tregs in old mice reprogram succinate metabolism to drive their suppressive ability which may be negatively regulated by FGF21. Thus, Treg-succinate-FGF21 may be a potential actionable pathway in precision targeting of EOC in the older population. Citation Format: Mary Priyanka Udumula, Harshit Singh, Faraz Rashid, Miriana Hijaz, Shailendra Giri, Ramandeep Rattan. Uncovering a novel role of succinate metabolism in tregulatory cells of aged epithelial ovarian cancer mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 851.

Abstract 7061: Targeting metabolic vulnerabilities in ARID1A/B dual-deficient dedifferentiated endometrial carcinoma

Abstract Background: Dedifferentiated endometrial carcinoma (DDEC) is an aggressive endometrial carcinoma defined histologically by undifferentiated carcinoma juxtaposed against stage 1 or 2 endometrial adenocarcinoma. DDEC responds poorly to conventional platinum/taxane-based chemotherapy, particularly in the case of extrauterine spread. This highlights a need to develop novel therapies for individuals with DDEC. Genetically, a third of DDEC cases have co-inactivating mutations of ARID1A and ARID1B. These genes encode core subunits of the sucrose/switch non-fermentable (SWI/SNF) complex that regulate transcription. Furthermore, dual loss of ARID1A/B is believed to play a role in driving DDEC tumor development. We hypothesize that ARID1A/B dual-deficiency in DDEC generates unique genetic deficiencies that allow for the development of novel therapies for this cancer. We approached this hypothesis by first conducting a preliminary analysis of the Cancer Dependency Map (DepMap), which has identified vulnerabilities in mitochondrial functioning in ARID1A/B dual-deficient DDECs. As such, we aimed to understand the role of mitochondrial oxidative phosphorylation (OXPHOS) and redox homeostasis in ARID1A/B dual-deficient DDEC to create new treatment options. Methods: A panel of ARID1A/B dual-deficient and proficient endometrial cancer cell lines were treated with OXPHOS inhibitor IACS-010759 and reactive oxidative species (ROS)-inducing agent elesclomol to identify shifts in drug response between the two groups. To account for genomic differences between the cell lines, we also treated an ARID1B knock-out isogeneic cell line with the drugs. Additionally, changes in metabolism in the endometrial cancer cell lines were measured using Seahorse metabolic flux assays to determine if ARID1A/B dual-deficient cell lines have an increased dependency on OXPHOS for cell growth. Results: While the Seahorse assays revealed no significant difference in OXPHOS and glycolysis activities between the two groups, drug sensitivity assays demonstrated that ARID1A/B dual-deficient cancers are more sensitive to OXPHOS inhibition and increased ROS production than the proficient cell lines. Depletion of ARID1B in an ARID1A deficient cell line sensitizes the cells to both drugs. Furthermore, IACS-010759 significantly suppressed the growth of ARID1A/B-deficient DDEC xenograft tumor growth. Conclusion: ARID1A/B-dual deficient cancer cells rely on mitochondria function for survival. The underlying mechanisms are currently under investigation. Citation Format: Rebecca Ho, Eunice Li, Chae Young Shin, Shary Chen, David Huntsman, Yemin Wang. Targeting metabolic vulnerabilities in ARID1A/B dual-deficient dedifferentiated endometrial carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7061.

Abstract 7062: CIP2A enhances mitochondrial respiratory electron transport chain complexes and induces lung cancer in vivo

Abstract Identification of oncogenes that can induce cancer in vivo is critical to elucidation of tumorigenesis and development of targeted therapies. Here, we reported for the first time that forced ectopic expression of CIP2A, the cancerous inhibitor of protein phosphatase 2A (PP2A), in lung tissues induced lung adenocarcinoma in mice. CIP2A upregulated the transcription and translation of mitochondrial DNA (mtDNA), and increases the enzymatic activity of mitochondrial electron transport chain (ETC) complex IV and V, thus enhancing the function of mitochondria and promoting the level of oxidative phosphorylation in tumors. CIP2A inhibited the binding of PP2A-B56α to FOXO3a, leading to the enhancement of the phosphorylation level of FOXO3a. The phosphorylated FOXO3a then translocated into the mitochondrion, and acted as a transcription factor to regulate CIP2A-mediated metabolic reprogramming in cancer cells. We found that oxidative phosphorylation inhibitors effectively inhibited CIP2A-induced cell proliferation. In non-small cell lung cancer, CIP2A level in tumor tissues was positively associated with the level of mtDNA. Our results indicated that CIP2A is able to induce lung adenocarcinoma in mice and has a critical role in mitochondrial oxidative phosphorylation, and represents a promising therapeutic target for non-small cell lung cancer. Competing interests: The authors declare no competing interests. Citation Format: Fu-Ying Yang, Di Wang, Li-Jun liang, Gui-Zhen Wang, Guang-Biao Zhou. CIP2A enhances mitochondrial respiratory electron transport chain complexes and induces lung cancer in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7062.

Co-delivery of Paclitaxel/Atovaquone/Quercetin to regulate energy metabolism to reverse multidrug resistance in ovarian cancer by PLGA-PEG nanoparticles

Ovarian cancer is a malignant tumor that seriously endangers the lives of women, with chemotherapy being the primary clinical treatment. However, chemotherapy encounters the problem of generating multidrug resistance (MDR), mainly due to drug efflux induced by P-glycoprotein (P-gp), which decreases intracellular accumulation of chemotherapeutic drugs. The drugs efflux mediated by P-gp requires adenosine triphosphate (ATP) hydrolysis to provide energy. Therefore, modulating energy metabolism pathways and inhibiting ATP production may be a potential strategy to reverse MDR. Herein, we developed a PTX-ATO-QUE nanoparticle (PAQNPs) based on a PLGA-PEG nanoplatform capable of loading the mitochondrial oxidative phosphorylation (OXPHOS) inhibitor atovaquone (ATO), the glycolysis inhibitor quercetin (QUE), and the chemotherapeutic drug paclitaxel (PTX) to reverse MDR by inhibiting energy metabolism through multiple pathways. Mechanistically, PAQNPs could effectively inhibit the OXPHOS and glycolytic pathways of A2780/Taxol cells by suppressing the activities of mitochondrial complex III and hexokinase II (HK II), respectively, ultimately decreasing intracellular ATP levels in tumor cells. Energy depletion can effectively inhibit cell proliferation and reduce P-gp activity, increasing the chemotherapeutic drug PTX accumulation in the cells. Moreover, intracellular reactive oxygen species (ROS) is increased with PTX accumulation and leads to chemotherapy-resistant cell apoptosis. Furthermore, PAQNPs significantly inhibited tumor growth in the A2780/Taxol tumor-bearing NCG mice model. Immunohistochemical (IHC) analysis of tumor tissues revealed that P-gp expression was suppressed, demonstrating that PAQNPs are effective in reversing MDR in tumors by inducing energy depletion. In addition, the safety study results, including blood biochemical indices, major organ weights, and H&E staining images, showed that PAQNPs have a favorable in vivo safety profile. In summary, the results suggest that the combined inhibition of the two energy pathways, OXPHOS and glycolysis, can enhance chemotherapy efficacy and reverse MDR in ovarian cancer.

Involvement of Ferroptosis Induction and Oxidative Phosphorylation Inhibition in the Anticancer-Drug-Induced Myocardial Injury: Ameliorative Role of Pterostilbene.

Patients with cancer die from cardiac dysfunction second only to the disease itself. Cardiotoxicity caused by anticancer drugs has been emphasized as a possible cause; however, the details remain unclear. To investigate this mechanism, we treated rat cardiomyoblast H9c2 cells with sunitinib, lapatinib, 5-fluorouracil, and cisplatin to examine their effects. All anticancer drugs increased ROS, lipid peroxide, and iron (II) levels in the mitochondria and decreased glutathione peroxidase-4 levels and the GSH/GSSG ratio. Against this background, mitochondrial iron (II) accumulates through the unregulated expression of haem oxygenase-1 and ferrochelatase. Anticancer-drug-induced cell death was suppressed by N-acetylcysteine, deferoxamine, and ferrostatin, indicating ferroptosis. Anticancer drug treatment impairs mitochondrial DNA and inhibits oxidative phosphorylation in H9c2 cells. Similar results were observed in the hearts of cancer-free rats treated with anticancer drugs in vitro. In contrast, treatment with pterostilbene inhibited the induction of ferroptosis and rescued the energy restriction induced by anticancer drugs both in vitro and in vivo. These findings suggest that induction of ferroptosis and inhibition of oxidative phosphorylation are mechanisms by which anticancer drugs cause myocardial damage. As pterostilbene ameliorates these mechanisms, it is expected to have significant clinical applications.

OXPHOS-targeted nanoparticles for boosting photodynamic therapy against hypoxia tumor

Hypoxia as an inherent feature in tumors is firmly associated with unsatisfactory clinical outcomes of photodynamic therapy (PDT) since the lack of oxygen leads to ineffective reactive oxygen species (ROS) productivity for tumor eradication. In this study, an oxidative phosphorylation (OXPHOS) targeting nanoplatform was fabricated to alleviate hypoxia and enhance the performance of PDT by encapsulating IR780 and OXPHOS inhibitor atovaquone (ATO) in triphenylphosphine (TPP) modified poly(ethylene glycol) methyl ether-block-poly(L-lactide-co-glycolide) (mPEG-PLGA) nanocarriers (TNPs/IA). ATO by interrupting the electron transfer in OXPHOS could suppress mitochondrial respiration of tumor cells, economising on oxygen for the generation of ROS. Benefiting from the mitochondrial targeting function of TPP, ATO was directly delivered to its site of action to obtain highlighted effect at a lower dosage. Furthermore, positioning the photosensitizer IR780 to mitochondria, a more vulnerable organelle to ROS, was a promising method to attenuate the spatiotemporal limitation of ROS caused by its short half-life and narrow diffusion radius. As a result, TNPs/IA exhibited accurate subcellular localization, lead to the collapse of ATP production by damaging mitochondrion and elicited significant antitumor efficacy via oxygen-augmented PDT in the HeLa subcutaneous xenograft model. Overall, TNPs/IA was a potential strategy in photodynamic eradication of tumors.

The down-regulation of GADD45B leads to a conversion of cellular oxidative phosphorylation to glycolysis and promotes the progression of bladder cancer

BackgroundThe predominant feature of cancer cells during the process of carcinogenesis is the inclination towards glycolytic metabolism rather than mitochondrial oxidative phosphorylation. Nevertheless, there is a scarcity of research investigating the correlation between bladder cancer and mitochondrial energy metabolism. MethodsA qPCR array comprising 90 genes associated with mitochondrial oxidative phosphorylation was employed to discern metabolic disparities between three sets of bladder cancer tissue and adjacent normal tissue. Wound healing and transwell assays were utilized to assess cell migration and invasion capabilities, respectively. Colony formation assays were conducted to ascertain the tumorigenic potential of the cells. The proliferative capacity of the cells was examined through in vitro CCK-8 assays. Additionally, nude mouse models were established to evaluate the impact of bladder tumor cells on in vivo proliferation. The Seahorse XFe96 Analyzer was utilized to quantify mitochondrial oxidative phosphorylation, while the levels of glucose-6-phosphate and pyruvate were assessed to evaluate glycolysis. ResultsExamination of qPCR array data demonstrated a noteworthy inhibition of mitochondrial oxidative phosphorylation in bladder cancer tissue, as evidenced by the down-regulation of a majority of genes associated with mitochondrial energy metabolism. Notably, GADD45B may potentially exert a significant influence on bladder cancer development, warranting further investigation. The down-regulation of GADD45B in bladder cancer cells resulted in impaired mitochondrial respiration and elevated levels of glycolysis, thereby enhancing cell migration and invasion. Conversely, up-regulation of GADD45B had the opposite effect. Furthermore, over-expression of GADD45B inhibited tumor proliferation and tumorigenesis in both in vitro and in vivo settings. ConclusionThese findings from our study indicate that the down-regulation of GADD45B promotes the shift of cell mitochondrial oxidative phosphorylation towards glycolysis, thereby facilitating the progression of bladder cancer.

Cysteine protease inhibitor 1 promotes metastasis by mediating an oxidative phosphorylation/MEK/ERK axis in esophageal squamous carcinoma cancer

Cysteine protease inhibitor 1 (CST1) is a cystatin superfamily protein that inhibits cysteine protease activity and is reported to be involved in the development of many malignancies. Mitochondrial oxidative phosphorylation (OXPHOS) also plays an important role in cancer cell growth regulation. However, the relationship and roles of CST1 and OXPHOS in esophageal squamous cell carcinoma (ESCC) remains unclear. In our pilot study, CST1 was shown the potential of promoting ESCC migration and invasion by the activation of MEK/ERK pathway. Transcriptome sequencing analysis revealed that CST1 is closely associated with OXPHOS. Based on a real-time ATP rate assay, mitochondrial complex I enzyme activity assay, immunofluorescence, co-immunoprecipitation, and addition of the OXPHOS inhibitor Rotenone and MEK/ERK inhibitor PD98059, we determined that CST1 affects mitochondrial complex I enzyme activity by interacting with the GRIM19 protein to elevate OXPHOS levels, and a reciprocal regulatory relationship exists between OXPHOS and the MEK/ERK pathway in ESCC cells. Finally, an in vivo study demonstrated the potential of CST1 in ESCC metastasis through regulation of the OXPHOS and MEK/ERK pathways. This study is the first to reveal the oncogenic role of CST1 in ESCC development by enhancing mitochondrial respiratory chain complex I activity to activate the OXPHOS/MEK/ERK axis, and then promote ESCC metastasis, suggesting that CST1/OXPHOS is a promising target for ESCC treatment.

Targeting mitochondrial bioenergetics by combination treatment with imatinib and dichloroacetate in human erythroleukemic K‑562 and colorectal HCT‑116 cancer cells.

Tumor malignant cells are characterized by dysregulation of mitochondrial bioenergetics due to the 'Warburg effect'. In the present study, this metabolic imbalance was explored as a potential target for novel cancer chemotherapy. Imatinib (IM) downregulates the expression levels of SCΟ2 and FRATAXIN (FXN) genes involved in the heme‑dependent cytochrome c oxidase biosynthesis and assembly pathway in human erythroleukemic IM‑sensitive K‑562 chronic myeloid leukemia cells (K‑562). In the present study, it was investigated whether the treatment of cancer cells with IM (an inhibitor of oxidative phosphorylation) separately, or together with dichloroacetate (DCA) (an inhibitor of glycolysis), can inhibit cell proliferation or cause death. Human K‑562 and IM‑chemoresistant K‑562 chronic myeloid leukemia cells (K‑562R), as well as human colorectal carcinoma cells HCT‑116 (+/+p53) and (‑/‑p53, with double TP53 knock-in disruptions), were employed. Treatments of these cells with either IM (1 or 2µM) and/or DCA (4mΜ) were also assessed for the levels of several process biomarkers including SCO2, FXN, lactate dehydrogenase A, glyceraldehyde‑3‑phosphate dehydrogenase, pyruvate kinase M2, hypoxia inducing factor‑1a, heme oxygenase‑1, NF‑κB, stem cell factor and vascular endothelial growth factor via western blot analysis. Computational network biology models were also applied to reveal the connections between the ten proteins examined. Combination treatment of IM with DCA caused extensive cell death (>75%) in K‑562 and considerable (>45%) in HCT‑116 (+/+p53) cultures, but less in K‑562R and HCT‑116 (‑/‑p53), with the latter deficient in full length p53 protein. Such treatment, markedly reduced reactive oxygen species levels, as measured by flow‑cytometry, in K‑562 cells and affected the oxidative phosphorylation and glycolytic biomarkers in all lines examined. These findings indicated, that targeting of cancer mitochondrial bioenergetics with such a combination treatment was very effective, although chemoresistance to IM in leukemia and the absence of a full length p53 in colorectal cells affected its impact.

Self-Delivery Nanomedicines Reverse Thermal Resistance to Enhance Tumor Mild-Temperature Photothermal Therapy.

Tumoral thermal defense mechanisms considerably attenuate the therapeutic outcomes of mild-temperature photothermal therapy (PTT). Thus, developing a simple, efficient, and universal therapeutic strategy to sensitize mild-temperature PTT is desirable. Herein, we report self-delivery nanomedicines ACy NPs comprising a near-infrared (NIR) photothermal agent (Cypate), mitochondrial oxidative phosphorylation inhibitor (ATO), and distearoylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), which have a high drug-loading efficiency that can reverse tumoral thermal resistance, thereby increasing mild-temperature PTT efficacy. ACy NPs achieved targeted tumor accumulation and performed NIR fluorescence imaging capability in vivo to guide tumor PTT for optimized therapeutic outcomes. The released ATO reduced intracellular ATP levels to downregulate multiple heat shock proteins (including HSP70 and HSP90) before PTT, which reversed the thermal resistance of tumor cells, contributing to the excellent results of mild-temperature PTT in vitro and in vivo. Therefore, this study provides a simple, biosafe, advanced, and universal heat shock protein-blocking strategy for tumor PTT.

Oxidative phosphorylation is a pivotal therapeutic target of fibrodysplasia ossificans progressiva.

Heterotopic ossification (HO) is a non-physiological bone formation where soft tissue progenitor cells differentiate into chondrogenic cells. In fibrodysplasia ossificans progressiva (FOP), a rare genetic disease characterized by progressive and systemic HO, the Activin A/mutated ACVR1/mTORC1 cascade induces HO in progenitors in muscle tissues. The relevant biological processes aberrantly regulated by activated mTORC1 remain unclear, however. RNA-sequencing analyses revealed the enrichment of genes involved in oxidative phosphorylation (OXPHOS) during Activin A-induced chondrogenesis of mesenchymal stem cells derived from FOP patient-specific induced pluripotent stem cells. Functional analyses showed a metabolic transition from glycolysis to OXPHOS during chondrogenesis, along with increased mitochondrial biogenesis. mTORC1 inhibition by rapamycin suppressed OXPHOS, whereas OXPHOS inhibitor IACS-010759 inhibited cartilage matrix formation in vitro, indicating that OXPHOS is principally involved in mTORC1-induced chondrogenesis. Furthermore, IACS-010759 inhibited the muscle injury-induced enrichment of fibro/adipogenic progenitor genes and HO in transgenic mice carrying the mutated human ACVR1. These data indicated that OXPHOS is a critical downstream mediator of mTORC1 signaling in chondrogenesis and therefore is a potential FOP therapeutic target.

Helicobacter pylori secretory Proteins-Induced oxidative stress and its role in NLRP3 inflammasome activation

Helicobacter pylori-associated stomach infection is a leading cause of gastric ulcer and related cancer. H. pylori modulates the functions of infiltrated immune cells to survive the killing by reactive oxygen and nitrogen species (ROS and RNS) produced by these cells. Uncontrolled immune responses further produce excess ROS and RNS which lead to mucosal damage. The persistent oxidative stress is a major cause of gastric cancer. H. pylori regulates nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs), nitric oxide synthase 2 (NOS2), and polyamines to control ROS and RNS release through lesser-known mechanisms. ROS and RNS produced by these pathways differentiate macrophages and T cells from protective to inflammatory phenotype. Pathogens-associated molecular patterns (PAMPs) induced ROS activates nuclear oligomerization domain (NOD), leucine rich repeats (LRR) and pyrin domain-containing protein 3 (NLRP3) inflammasome for the release of pro-inflammatory cytokines. This study evaluates the role of H. pylori secreted concentrated proteins (HPSCP) related oxidative stress role in NLRP3 inflammasome activation and macrophage differentiation. To perceive the role of ROS/RNS, THP-1 and AGS cells were treated with 10 μM diphenyleneiodonium (DPI), 50 μM salicyl hydroxamic acid (SHX), 5 μM Carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone (FCCP), which are specific inhibitors of NADPH oxidase (NOX), Myeloperoxidase (MPO), and mitochondrial oxidative phosphorylation respectively. Cells were also treated with 10 μM of NOS2 inhibitor l-NMMA and 10 μM of N-acetyl cysteine (NAC), a free radical scavenger·H2O2 (100 μM) treated and untreated cells were used as positive controls and negative control respectively. The expression of gp91phox (NOX2), NOS2, NLRP3, CD86 and CD163 was analyzed through fluorescent microscopy. THP-1 macrophages growth was unaffected whereas the gastric epithelial AGS cells proliferated in response to higher concentration of HPSCP. ROS and myeloperoxidase (MPO) level increased in THP-1 cells and nitric oxide (NO) and lipid peroxidation significantly decreased in AGS cells. gp91phox expression was unchanged, whereas NOS2 and NLRP3 downregulated in response to HPSCP, but increased after inhibition of NO, ROS and MPO in THP-1 cells. HPSCP upregulated the expression of M1 and M2 macrophage markers, CD86 and CD163 respectively, which was decreased after the inhibition of ROS.This study concludes that there are multiple pathways which are generating ROS during H. pylori infection which further regulates other cellular processes. NO is closely associated with MPO and inhibition of NLRP3 inflammasome. The low levels of NO and MPO regulates gastrointestinal tract homeostasis and overcomes the inflammatory response of NLRP3. The ROS also plays crucial role in macrophage polarization hence alter the immune responses duing H. pylori pathogenesis.

Metabolic reprogramming driven by METTL1-mediated tRNA m7G modification promotes acquired anlotinib resistance in oral squamous cell carcinoma

Tyrosine kinase inhibitors (TKIs) are frequently utilized in the management of malignant tumors. Studies have indicated that anlotinib has a significant inhibitory effect on oral squamous cell carcinoma (OSCC). However, the mechanisms underlying the development of resistance with long-term anlotinib treatment remain obscure. Our research found that METTL1 expression was heightened in anlotinib-resistant OSCC cells. We observed that METTL1 played a role in fostering resistance to anlotinib in both transgenic mouse models and in vitro. Mechanistically, the elevated METTL1 levels in anlotinib-resistant OSCC cells contributed to enhanced global mRNA translation and stimulated oxidative phosphorylation (OXPHOS) through m7G tRNA modification. Bioenergetic profiling demonstrated that METTL1 drived a metabolic shift from glycolysis to OXPHOS in anlotinib-resistant OSCC cells. Additionally, inhibition of OXPHOS biochemically negated METTL1′s impact on anlotinib resistance. Overall, this study underscores the pivotal role of METTL1-mediated m7G tRNA modification in anlotinib resistance and lays the groundwork for novel therapeutic interventions to counteract resistance in OSCC.

TR-57 Treatment of SUM159 Cells Induces Mitochondrial Dysfunction without Affecting Membrane Potential.

Recent works identified ClpXP, mitochondrial caseinolytic protease, as the only target of imipridones, a new class of antitumor agents. Our study of the mechanism of imipridone derivative TR-57 action in SUM159 human breast cancer cells demonstrated mitochondrial fragmentation, degradation of mitochondrial mtDNA and mitochondrial dysfunction due to inhibition of Complex I and Complex II activity. Complete inhibition of oxidative phosphorylation accompanied 90, 94, 88 and 87% decreases in the content of Complex I, II, III and IV proteins, respectively. The content of the FOF1-ATPase subunits decreased sharply by approximately 35% after 24 h and remained unchanged up to 72 h of incubation with TR-57. At the same time, a disappearance of the ATPIF1, the natural inhibitor of mitochondrial FOF1-ATPase, was observed after 24 h exposure to TR-57. ATPase inhibitor oligomycin did not affect the mitochondrial membrane potential in intact SUM159, whereas it caused a 65% decrease in TR-57-treated cells. SUM159 cells incubated with TR57 up to 72 h retained the level of proteins facilitating the ATP transfer across the mitochondrial membranes: VDAC1 expression was not affected, while expression of ANT-1/2 and APC2 increased by 20% and 40%, respectively. Thus, our results suggest that although TR-57 treatment leads to complete inhibition of respiratory chain activity of SUM159 cells, hydrolysis of cytoplasmic ATP by reversal activity of FOF1-ATPase supports mitochondrial polarization.

Abstract C049: Loss of RNF43 creates an OXPHOS dependency in early pancreatic neoplasia

Abstract Pancreatic ductal adenocarcinoma (PDAC) has a dismal 5-year survival of 12%. RNF43 is frequently mutated in pancreatic cystic neoplasms, including intraductal papillary mucinous neoplasms (IPMNs), which are precursor lesions of PDAC. RNF43 encodes for an E3 ubiquitin ligase and was initially identified as a negative Wnt regulator. To elucidate the role of RNF43-mutated neoplasms in an organ specific context, we have generated a genetically engineered mouse model which has pancreas specific loss of RNF43 (Hosein, Gastroenterology 2022). In this study we examine some of the metabolic dependencies created by Rnf43 loss on the background of mutant Kras, and how the Kras;Rnf43 model differs from the commonly used Kras;p53 model of PDAC. We have generated cell lines harboring mutant Kras and bi-allelic loss of Rnf43 from the resulting lesions in these mice (henceforth referred to as Kras;Rnf43 lines).Isogenic Kras;Rnf43 cell lines with re-expression of full-length Rnf43 (Kras;Rnf43-RNF43OE) were generated to confirm if observed phenotypes were Rnf43 dependent. Single-cell RNA sequencing (scRNA-seq) was performed for comparison between murine PDAC arising in Kras;Rnf43 versus Kras;p53 mice. We further compared metabolic parameters in Kras;Rnf43 and Kras;Rnf43-RNF43OE cells using the Seahorse platform. Mitochondrial ultrastructure by transmission electron microscopy (TEM) was analyzed in Kras;Rnf43 compared to Kras;p53 cells. To visualize endoplasmic reticulum (ER)-mitochondria contact sites (ERMCS), a split green fluorescent protein-based contact site sensor (SPLICS) was transfected and analyzed. Compared to Kras;p53 PDAC, Kras;Rnf43 tumors demonstrated upregulated mitochondrial transcripts and gene signatures of ER stress. Further, the ER stress response protein IRE1 was markedly elevated in Kras;Rnf43 cells versus Kras;p53 cells. The Kras;Rnf43 lines had enhanced mitochondrial oxidative phosphorylation (OXPHOS) activity and demonstrated evidence of enhanced mitochondrial quality control. ERMCS is a dynamic contact region between ER and mitochondria, which regulates biological processes including calcium homeostasis, ER stress and mitochondrial dynamics. The Kras;Rnf43 cells had significantly increased ERMCS compared to Kras;p53 cells. Finally, using IACS-010759, a small molecule inhibitor of OXPHOS, we demonstrate that Kras;Rnf43 cells had both increased in vitro sensitivity as well as in vivo susceptibility to tumor growth inhibition in orthotopic models, which translated into increased overall survival of mice. In conclusion, we provide evidence showing that bi-allelic loss of RNF43 is associated with increased ER stress and enhanced IRE1 dependent stress response. ER stress is mitigated via increased mitochondrial OXPHOS and ERMCS. Importantly, our results suggest that this creates a metabolic synthetic essentiality in the context of RNF43 loss, providing an avenue to suppress the progression of RNF43-mutated IPMNs, and potentially other solid cancers by targeting mitochondrial OXPHOS. Citation Format: Akiko Sagara, Brandon Chen, Nathaniel G. Yee, Megan J. Siemann, Costas A. Lyssiotis, Yatrik M. Shah, Sonja M. Woermann, Anirban Maitra. Loss of RNF43 creates an OXPHOS dependency in early pancreatic neoplasia [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr C049.

Abstract B058: Mutant GNAS drives glycolytic dependency in intraductal papillary mucinous neoplasms of the pancreas

Abstract Oncogenic “hotspot” mutations of KRAS and GNAS are two major driver alterations in Intraductal Papillary Mucinous Neoplasms (IPMNs), which are bona fide precursor lesions of pancreatic ductal adenocarcinoma (PDAC). We previously reported that pancreas-specific KrasG12D and GnasR201C expression caused IPMN development, with subsequent progression to PDAC in p48-Cre; LSL-KrasG12D; Rosa26R-LSL-rtTA-TetO-GnasR201C mice (referred to as “Kras;Gnas” mice). This study aimed to clarify the functional roles of mutant GNAS, thereby investigating therapeutic dependencies that exist in the context of mutant KRAS and GNAS co-expression in IPMN. We established cell lines derived from IPMN-associated PDAC in Kras;Gnas mice (referred to as “Kras;Gnas” cells), in which KrasG12D is constitutively active whereas GnasR201C expression is inducible by the addition of doxycycline. RNA-sequencing of Kras;Gnas cells identified the enrichment of glycolysis-related gene signatures upon GnasR201C induction. This was also confirmed on single cell RNA sequencing data of IPMN-associated PDAC in Kras;Gnas mice, when compared with tumors arising in mice expressing mutant KrasG12D alone. Genome-wide CRISPR/Cas9 screening identified multiple glycolysis-related genes as essential genes in the setting of KrasG12D and GnasR201C co-expression in Kras;Gnas cells. Further, Seahorse metabolic flux analyzer showed the enhancement of glycolysis by GnasR201C induction in Kras;Gnas cells. In vivo, 13C-hyperpolarized MRI (HP-MRI) revealed the enhancement of glycolytic flux (pyruvate to lactate conversion) in Kras;Gnas mice with concurrent GnasR201C expression, compared to mice with KrasG12D alone. The GNASR201C-expressing Kras;Gnas cells were also more susceptible to glycolysis inhibition either by glucose deprivation or upon exposure to inhibitors of glycolysis, when compared to cells with only KrasG12D expression. Knockout of Gpi1 or Slc2a1, two synthetic lethal glycolysis associated genes identified on CRISPR/Cas9 screening, significantly suppressed cell growth in GNASR201C-expressing Kras;Gnas cells both in vitro and in vivo. Of note, Gpi1 deletion increased compensatory ATP production from mitochondrial oxidative phosphorylation (OXPHOS) and autophagy in GNASR201C-expressing Kras;Gnas cells and as a result, these cells were more susceptible to both inhibitors of OXPHOS and of autophagy. We identified two candidate effector pathways downstream of GNASR201C activation - PKA/PFKFB3 and EPAC/DRP1 – which were responsible for the increased glycolytic activity observed via multiple orthogonal approaches in Kras;Gnas cells. The expression of phospho-PFKFB3, Gpi1, and Glut1 proteins were elevated in human IPMN lesions with GNAS mutations. In conclusion, the co-occurrence of hot spot GNAS mutations enhances glycolysis in IPMNs arising in the context of KRAS mutations. Targeting glycolysis might be a potential avenue for treatment and cancer interception in IPMN lesions with co-mutations of KRAS and GNAS. Citation Format: Yuki Makino, Kimal Rajapakshe, Nathaniel Yee, Megan Siemann, Jimin Min, Benson Chellakkan Selvanesan, Fredrik Thege, Akiko Sagara, Prasanta Dutta, Pratip Bhattacharya, Merve Dede, Traver Hart, Anirban Maitra. Mutant GNAS drives glycolytic dependency in intraductal papillary mucinous neoplasms of the pancreas [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B058.