Unraveling malignant phenotype of peritumoral tissue: transcriptomic insights into early-stage breast cancer.

BACKGROUND: Early-stage invasive ductal carcinoma displays high survival rates due to early detection and treatments. However, there is still a chance of relapse of 3-15% after treatment. The aim of this study was to uncover the distinctive transcriptomic characteristics and monitoring prognosis potential of peritumoral tissue in early-stage cases. METHODS: RNA was isolated from tumoral, peritumoral, and non-tumoral breast tissue from surgical resection of 10 luminal early-stage invasive ductal carcinoma patients. Transcriptome expression profiling for differentially expressed genes (DEGs) identification was carried out through microarray analysis. Gene Ontology and KEGG pathways enrichment analysis were explored for functional characterization of identified DEGs. Protein-Protein Interactions (PPI) networks analysis was performed to identify hub nodes of peritumoral tissue alterations and correlated with Overall Survival and Relapse Free Survival. RESULTS: DEGs closely related with cell migration, extracellular matrix organization, and cell cycle were upregulated in peritumoral tissue compared to non-tumoral. Analyzing PPI networks, we observed that the proximity to tumor leads to the alteration of gene modules involved in cell proliferation and differentiation signaling pathways. In fact, in the peritumoral area were identified the top ten upregulated hub nodes including CDK1, ESR1, NOP58, PCNA, EZH2, PPP1CA, BUB1, TGFBR1, CXCR4, and CCND1. A signature performed by four of these hub nodes (CDK1, PCNA, EZH2, and BUB1) was associated with relapse events in untreated luminal breast cancer patients. CONCLUSIONS: In conclusion, our study characterizes in depth breast peritumoral tissue providing clues on the changes that tumor signaling could cause in patients with early-stage breast cancer. We propose that the use of a four gene signature could help to predict local relapse. Overall, our results highlight the value of peritumoral tissue as a potential source of new biomarkers for early detection of relapse and improvement in invasive ductal carcinoma patient's prognosis.

Mitochondrial Functionality Is Regulated by Alkylphospholipids in Human Colon Cancer Cells.

Alkylphospholipids (APLs) have been studied as anticancer drugs that interfere with biological membranes without targeting DNA. Although their mechanism of action is not fully elucidated yet, it is known that they disrupt the intracellular trafficking of cholesterol and its metabolism. Here, we analyzed whether APLs could also interfere with mitochondrial function. For this purpose, we used HT29 colorectal cancer cells, derived from a primary tumor, and SW620 colorectal cancer cells, derived from a metastasis site. After treatment with the APLs miltefosine and perifosine, we analyzed various mitochondrial parameters, including mitochondrial mass, cardiolipin content, mitochondrial membrane potential, H2O2 production, the levels of oxidative phosphorylation (OXPHOS) complexes, metabolic enzymes activity, the oxygen consumption rate, and the levels of apoptosis and autophagy markers. APLs, especially perifosine, increased mitochondrial mass while OXPHOS complexes levels were decreased without affecting the total oxygen consumption rate. Additionally, we observed an increase in pyruvate dehydrogenase (PDH) and isocitrate dehydrogenase (IDH) levels and a decrease in lactate dehydrogenase (LDH) activity, suggesting a metabolic rewiring induced by perifosine. These alterations led to higher mitochondrial membrane potential, which was potentiated by decreased uncoupling protein 2 (UCP2) levels and increased reactive oxygen species (ROS) production. Consequently, perifosine induced an imbalance in mitochondrial function, resulting in higher ROS production that ultimately impacted cellular viability.

Isolation and Characterization of Extracellular Vesicles in Human Bowel Lavage Fluid.

Colorectal cancer (CRC) is the third most common cancer worldwide and is detected in late stages because of a lack of early and specific biomarkers. Tumors can release extracellular vesicles (EVs), which participate in different functions, such as carrying nucleic acids to target cells; promoting angiogenesis, invasion, and metastasis; and preparing an adequate tumor microenvironment. Finally, bowel lavage fluid (BLF) is a rarely used sample that is obtained during colonoscopy. It presents low variability and protein degradation, is easy to handle, and is representative of EVs from tumor cells due to proximity of the sample collection. This sample has potential as a research tool and possible biomarker source for CRC prognosis and monitoring. In this study, EVs were isolated from human BLF by ultracentrifugation, then characterized by transmission electron microscopy and atomic force microscopy. EV concentration was determined by nanoparticle tracking analysis, and tetraspanins were determined by Western blot, confirming correct EV isolation. RNA, DNA, and proteins were isolated from these EVs; RNA was used in real-time PCR, and proteins were used in an immunoblotting analysis, indicating that EV cargo is optimal for use and study. These results indicate that EVs from BLF can be a useful tool for CRC study and could be a source of biomarkers for the diagnosis and monitoring of CRC.

Inflammation-Related Signature Profile Expression as a Poor Prognosis Marker after Oxaliplatin Treatment in Colorectal Cancer.

Oxaliplatin is successfully used to eradicate micro-metastasis and improve survival, whereas the benefit of adjuvant chemotherapy in the early stages of colorectal cancer remains controversial. Inflammation plays a crucial role in colorectal cancer tumorigenesis. Inflammatory mechanisms are mediated by different immune cells through different cytokines, chemokines, and other proinflammatory molecules that trigger cell progression, an increase of cancer stem cell population, hyperplasia, and metastasis. This study focuses on the analysis of the oxaliplatin effect on tumourspheres formation efficiency, cell viability, cancer stem cells and stemness marker mRNA expression, as well as inflammation-related signature profile expression and its prognosis in primary- and metastatic-derived colorectal tumourspheres derived from colorectal cell lines isolated from the same patient 1 year apart. The results indicate that primary-derived colorectal tumourspheres respond to oxaliplatin, adapting to the adverse conditions through the modulation of CSCs and the stemness properties of tumourspheres. However, metastatic-derived colorectal tumourspheres response led to the release of cytokines and chemokines, promoting an inflammatory process. In addition, the expression of inflammatory markers showing greater difference between primary and metastatic tumours after oxaliplatin treatment correlates with poor prognosis in KM survival studies and is associated with a metastatic phenotype. Our data demonstrated that oxaliplatin triggers an inflammation-related signature profile expression in primary-derived colorectal tumourspheres, related with poor prognosis and a metastatic phenotype, which allow the tumour cells to adapt to the adverse condition. These data highlight the need for of drug testing and personalized medicine in the early stages of colorectal cancer.

Sex Specific Differences in Response to Calorie Restriction in Skeletal Muscle of Young Rats.

Calorie restriction (CR), defined as a reduction of the total calorie intake of 30% to 60% without malnutrition, is the only nutritional strategy that has been shown to extend lifespan, prevent or delay the onset of age-associated diseases, and delay the functional decline in a wide range of species. However, little is known about the effects of CR when started early in life. We sought to analyze the effects of CR in the skeletal muscle of young Wistar rats. For this, 3-month-old male and female rats were subjected to 40% CR or fed ad libitum for 3 months. Gastrocnemius muscles were used to extract RNA and total protein. Western blot and RT-qPCR were performed to evaluate the expression of key markers/pathways modulated by CR and affected by aging. CR decreased body and skeletal muscle weight in both sexes. No differences were found in most senescence, antioxidant, and nutrient sensing pathways analyzed. However, we found a sexual dimorphism in markers of oxidative stress, inflammation, apoptosis, and mitochondrial function in response to CR. Our data show that young female rats treated with CR exhibit similar expression patterns of key genes/pathways associated with healthy aging when compared to old animals treated with CR, while in male rats these effects are reduced. Additional studies are needed to understand how early or later life CR exerts positive effects on healthspan and lifespan.

Inflammation- and Metastasis-Related Proteins Expression Changes in Early Stages in Tumor and Non-Tumor Adjacent Tissues of Colorectal Cancer Samples.

Chronic inflammation can induce malignant cell transformation, having an important role in all colorectal cancer (CRC) phases. Non-tumor adjacent tissue plays an important role in tumor progression, but its implication in CRC has not yet been fully elucidated. The aim was to analyze the expression of inflammatory, epithelial-mesenchymal transition (EMT), and metastasis-related proteins in both tumor and non-tumor adjacent tissues from CRC patients by western blot. Tumor tissue presented an increase in metastasis and EMT-related proteins compared to non-tumor adjacent tissue, especially in stage II. Tumor tissue stage II also presented an increase in inflammatory-related proteins compared to other stages, which was also seen in non-tumor adjacent tissue stage II. Additionally, the relapse-free survival study of Vimentin and VEGF-B expression levels in stage II patients showed that the higher the expression levels of each protein, the lower 10-year relapse-free survival. These could suggest that some metastasis-related signalling pathways may be activated in stage II in tumor tissue, accompanied by an increase in inflammation. Furthermore, non-tumor adjacent tissue presented an increase of the inflammatory status that could be the basis for future tumor progression. In conclusion, these proteins could be useful as biomarkers of diagnosis for CRC at early stages.

High Concentrations of Genistein Decrease Cell Viability Depending on Oxidative Stress and Inflammation in Colon Cancer Cell Lines.

Genistein could play a crucial role in modulating three closely linked physiological processes altered during cancer: oxidative stress, mitochondrial biogenesis, and inflammation. However, genistein's role in colorectal cancer remains unclear. We aimed to determine genistein's effects in two colon cancer cells: HT29 and SW620, primary and metastatic cancer cells, respectively. After genistein treatment for 48 h, cell viability and hydrogen peroxide (H2O2) production were studied. The cell cycle was studied by flow cytometry, mRNA and protein levels were analyzed by RT-qPCR and Western blot, respectively, and finally, cytoskeleton remodeling and NF-κB translocation were determined by confocal microscopy. Genistein 100 µM decreased cell viability and produced G2/M arrest, increased H2O2, and produced filopodia in SW620 cells. In HT29 cells, genistein produced an increase of cell death, H2O2 production, and in the number of stress fibers. In HT29 cells, mitochondrial biogenesis was increased, however, in SW620 cells, it was decreased. Finally, the expression of inflammation-related genes increased in both cell lines, being greater in SW620 cells, where NF-κB translocation to the nucleus was higher. These results indicate that high concentrations of genistein could increase oxidative stress and inflammation in colon cancer cells and, ultimately, decrease cell viability.

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

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.

Use of Omics Technologies for the Detection of Colorectal Cancer Biomarkers.

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers with high mortality rates, especially when detected at later stages. Early detection of CRC can substantially raise the 5-year survival rate of patients, and different efforts are being put into developing enhanced CRC screening programs. Currently, the faecal immunochemical test with a follow-up colonoscopy is being implemented for CRC screening. However, there is still a medical need to describe biomarkers that help with CRC detection and monitor CRC patients. The use of omics techniques holds promise to detect new biomarkers for CRC. In this review, we discuss the use of omics in different types of samples, including breath, urine, stool, blood, bowel lavage fluid, or tumour tissue, and highlight some of the biomarkers that have been recently described with omics data. Finally, we also review the use of extracellular vesicles as an improved and promising instrument for biomarker detection.

Xanthohumol reduces inflammation and cell metabolism in HT29 primary colon cancer cells.

Xanthohumol (XN) is a prenylated flavonoid known for its antioxidant and anti-inflammatory effects and has been studied as an anti-cancer agent. In this study, we aimed at analysing the effect of XN on a primary colorectal adenocarcinoma cell line, HT29, on cell viability, inflammatory and antioxidant gene expression, and metabolism. For this purpose, cells were treated with 10 nM and 10 µM XN, and cell viability, H2O2 production, lipid peroxidation and gene expression of inflammatory, antioxidant, and mitochondrial-related genes, as well as protein levels of metabolic enzymes, were determined. Results showed no significant effects on cell viability and a general decrease in pro-inflammatory, antioxidant and mitochondrial biogenesis gene expression with the lower concentration of XN. Furthermore, glucose and oxidative metabolism enzymes were also reduced. These results suggest that XN treatment, at low doses, could stop the proliferation and progression of HT29 cells by downregulating inflammatory signals and cell metabolism.

Estrogen Receptor Beta (ERß) Maintains Mitochondrial Network Regulating Invasiveness in an Obesity-Related Inflammation Condition in Breast Cancer.

Obesity, a physiological situation where different proinflammatory cytokines and hormones are secreted, is a major risk factor for breast cancer. Mitochondrial functionality exhibits a relevant role in the tumorigenic potential of a cancer cell. In the present study, it has been examined the influence of an obesity-related inflammation ELIT treatment (17ß-estradiol, leptin, IL-6, and TNFα), which aims to stimulate the hormonal conditions of a postmenopausal obese woman on the mitochondrial functionality and invasiveness of MCF7 and T47D breast cancer cell lines, which display a different ratio of both estrogen receptor isoforms, ERα and ERß. The results showed a decrease in mitochondrial functionality, with an increase in oxidative stress and invasiveness and motility, in the MCF7 cell line (high ERα/ERß ratio) compared to a maintained status in the T47D cell line (low ERα/ERß ratio) after ELIT treatment. In addition, breast cancer biopsies were analyzed, showing that breast tumors of obese patients present a high positive correlation between IL-6 receptor and ERß and have an increased expression of cytokines, antioxidant enzymes, and mitochondrial biogenesis and dynamics genes. Altogether, giving special importance to ERß in the pathology of obese patients with breast cancer is necessary, approaching to personalized medicine.

Micronutrients Selenomethionine and Selenocysteine Modulate the Redox Status of MCF-7 Breast Cancer Cells.

Selenium is a micronutrient which is found in many foods, with redox status modulation activity. Our aim was to evaluate the effects of two chemical forms of selenoamino acids, Seleno-L-methionine and Seleno-L-cystine (a diselenide derived from selenocysteine), at different concentrations on cell viability, hydrogen peroxide production, antioxidant enzymes, UCP2 protein expression, as well as lipid and protein oxidative damage in MCF-7 breast cancer cells. Results showed that Seleno-L-methionine did not cause an increase in hydrogen peroxide production at relatively low concentrations, accompanied by a rise in the antioxidant enzymes catalase and MnSOD, and UCP2 protein expression levels. Furthermore, a decrease in protein and lipid oxidative damage was observed at 10 µM concentration. Otherwise, Seleno-L-cystine increased hydrogen peroxide production from relatively low concentrations (100 nM) to a large increase at high concentrations. Moreover, at 10 µM, Seleno-L-cystine decreased UCP2 and MnSOD protein expression. In conclusion, the chemical form of selenoamino acid and their incorporation to selenoproteins could affect the regulation of the breast cancer cell redox status. Taken together, the results obtained in this study imply that it is important to control the type of selenium-enriched nutrient consumption, taking into consideration their composition and concentration.

Sexual hormones regulate the redox status and mitochondrial function in the brain. Pathological implications.

Compared to other organs, the brain is especially exposed to oxidative stress. In general, brains from young females tend to present lower oxidative damage in comparison to their male counterparts. This has been attributed to higher antioxidant defenses and a better mitochondrial function in females, which has been linked to neuroprotection in this group. However, these differences usually disappear with aging, and the incidence of brain pathologies increases in aged females. Sexual hormones, which suffer a decrease with normal aging, have been proposed as the key factors involved in these gender differences. Here, we provide an overview of redox status and mitochondrial function regulation by sexual hormones and their influence in normal brain aging. Furthermore, we discuss how sexual hormones, as well as phytoestrogens, may play an important role in the development and progression of several brain pathologies, including neurodegenerative diseases such as Alzheimer's and Parkinson's diseases, stroke or brain cancer.

Antioxidant enzymes change in different non-metastatic stages in tumoral and peritumoral tissues of colorectal cancer.

Antioxidant defences and oxidative stress are related to development, progression and malignancy of colorectal cancer. However, their role in early stages of cancer remains unknown. More and more recent studies have revealed that non-tumour adjacent tissue is not a normal tissue. Thus, our aim was to analyse protein levels of MnSOD (Manganese Superoxide Dismutase), acMnSOD (Acetylated Manganese superoxide Dismutase), SIRT3 (Sirtuin 3), CuZnSOD (Cupper Zinc Superoxide Dismutase), CAT (Catalase), GPx (Glutathione Peroxidase), and GRd (Glutathione Reductase) both in tumour and non-tumour adjacent tissue from colorectal cancer patients by western blot. Non-tumour adjacent tissue seemed to have higher levels of antioxidant enzymes that detoxify hydrogen peroxide compared to tumour tissue. In contrast, tumour tissue had higher levels of MnSOD and acMnSOD. Furthermore, most of the proteins analysed showed significant differences between stage I and II in both non-tumour adjacent and tumour tissue. This could indicate that antioxidant enzymes, especially MnSOD, play a crucial role in early stages of colorectal cancer in both tissues, so they could be analysed as novel biomarkers to improve colorectal cancer diagnosis.

Mutant p53 induces SIRT3/MnSOD axis to moderate ROS production in melanoma cells.

The TP53 tumor suppressor gene is the most frequently altered gene in tumors and mutant p53 isoforms can acquire oncogenic properties referred to as gain-of-function (GOF). In this study, we used wild-type (A375) and mutant p53 (MeWo) melanoma cell lines to assess the regulation of the mitochondrial antioxidant manganese superoxide dismutase (MnSOD) by mutant p53. The effects of mutant p53 were evaluated by qPCR, immunoblotting, enzyme activity assay, cell proliferation assay, reactive oxygen species (ROS) assay after cellular transfection. We demonstrate that mutant p53 induces MnSOD expression, which is recovered by the ROS scavenger N-acetyl-l-cysteine. This suggests MnSOD induction as a defense mechanism of melanoma cells to counterbalance the pro-oxidant conditions induced by mutant p53. We also demonstrate that mutant p53 induces the expression of Sirtuin3 (SIRT3), a major mitochondrial NAD+-dependent deacetylase, stimulating MnSOD deacetylation and enzymatic activity. Indeed, the restoration of SIRT3 reverses MnSOD activity decrease by mutant p53 knock-down. Finally, MnSOD knock-down further enhances mutant p53-mediated ROS increase, counteracting mutp53-dependent cell hyperproliferation. This indicates that SIRT3 and MnSOD act to maintain ROS levels controlled to promote cell proliferation and survival, providing new therapeutic opportunities to be further considered for clinical studies in cancer patients bearing mutant TP53 gene.

Sirtuin 3 silencing impairs mitochondrial biogenesis and metabolism in colon cancer cells.

Sirtuin 3 (SIRT3) is the main mitochondrial deacetylase and targets several crucial enzymes against oxidative stress. Recent reports suggest that SIRT3 could also participate in the quality and quantity control of mitochondria. The aim of this study was to analyze whether SIRT3 silencing in colon cancer cells could affect mitochondrial biogenesis and impair mitochondrial function. For this purpose, metastatic colon cancer cell line SW620 was transfected with a specific shRNA against SIRT3 to obtain a stable knockdown. Gene expression and protein levels of several proteins related to mitochondrial biogenesis and function were determined by RT-qPCR and Western blotting. Mitochondrial function was studied by analyzing COX, ATPase, and LDH enzymatic activities, oxygen consumption, superoxide levels, and mitochondrial membrane potential. Confocal images were also taken to study mitochondrial morphology, and cell motility and clonogenicity were also studied. SIRT3 silencing resulted in a reduced mitochondrial biogenesis and function, as evidenced by the decrease in proteins such as PGC-1α and mitochondrial transcription factor A and lower levels of OXPHOS complexes. Furthermore, COX activity and oxygen consumption were also diminished after SIRT3 knockdown. Finally, SIRT3-silenced cells showed mitochondrial aggregation compared with control cells as well as reduced motility and colony formation ability. In conclusion, SIRT3 silencing in SW620 cancer cells leads to decreased mitochondrial biogenesis and mitochondrial dysfunction, ultimately affecting cell viability and could be a therapeutic strategy to render cells more sensitive to treatment.

The phytoestrogen genistein affects inflammatory-related genes expression depending on the ERα/ERß ratio in breast cancer cells.

Breast cancer is the most common malignancy in women of developed countries. The aim of this study was to investigate the effects of the phytoestrogen genistein on the inflammatory profile in three breast cancer cell lines with different oestrogen receptors alpha (ERα) and beta (ERß) ratio. MCF-7 (high ERα/ERß ratio), T47D (low ERα/ERß ratio), and MDA-MB-231 (ERα-negative) cells were treated with 1 µM of genistein for 48 h (cell proliferation and ROS production) or 4 h (mRNA expression of 18S, ERα, ERß, pS2, Sirtuin1, IL-1ß, NF-κB, COX-2, TGFß1, PPARγ). Genistein caused a significant decrease in cell viability and an increase in ROS production in MCF-7, and the opposite happens in T47D cells. In addition, genistein rise pro-inflammatory and reduced anti-inflammatory genes expression in MCF-7, provoking the opposite effects in T47D cells. In conclusion, the phytoestrogen genistein could modulate the expression of inflammatory-related genes through its interaction with both ERs, and its effects depends on the ERα/ERß ratio.

Thermogenic capacity in subterranean Ctenomys: Species-specific role of thermogenic mechanisms.

One way to understand ecological patterns of species is to determine their physiological diversity on a large geographic and/or temporal scales, in a context of hierarchical biodiversity framework. In particular, macrophysiological studies analyze how environmental factors affect the physiology and therefore the distribution of species. Subterranean species are an excellent model for evaluating the large-scale effects of ambient temperature (Ta) conditions on thermal physiology and distribution, due to their extensive use of burrows that provide a relatively thermal stable environment. Species belonging to the genus Ctenomys are all subterranean and endemic of South America. Cold induced maximum metabolic rate (MMR), basal metabolic rate (BMR) and non shivering thermogenesis (NST) were analyzed, as well as the expression of uncoupled proteins (UCP) in brown adipose tissue (BAT). Biogeographical variables appear to have no effect MMR experimentally induced by cold condition within Ctenomys. Also, mechanisms of heat production are species-specific, varying from a combination of ST and NST to a complete use of shivering mechanisms. This pattern is correlated at tissue level, since species that use only ST show a smaller interscapular BAT patch, not detectable presence of UCP1 and low COX activity. Thus, other factors, including body mass, that constrain cold induced MMR could affect thermogenic variability among Ctenomys. In the evolutionary timescale, if low O2 levels of burrows impose a ceiling in cold induced MMR, and ST is enhanced due to species-specific life history traits, such as digging effort, then the observed differences among Ctenomys species might be explained.

Xanthohumol, a hop-derived prenylflavonoid present in beer, impairs mitochondrial functionality of SW620 colon cancer cells.

Xanthohumol (XN) is a hop-derived prenylflavonoid and have been reported to exhibit anticancer properties in several types of cancer. It presents a great interest against colon cancer due to high exposure of this compound in this tissue. Metastatic SW620 cell line was treated with doses ranging from 0.001 to 10 µM of XN to assess their effects on cell viability and mitochondrial function. At low concentrations, XN had no effect on assays carried out, but high concentration of XN led to a decrease in cell viability. In addition, at 10 µM XN, it gave rise to an increase in ROS production accompanied by a decrease in OXPHOS complexes and sirtuin 1 protein expression levels. These results suggest that XN could act as a mitocan and impairs mitochondrial function.

Mutant p53 blocks SESN1/AMPK/PGC-1α/UCP2 axis increasing mitochondrial O2-· production in cancer cells.

BACKGROUND: The TP53 tumor suppressor gene is the most frequently altered gene in tumors and mutant p53 gain-of-function isoforms actively promote cancer malignancy. METHODS: A panel of wild-type and mutant p53 cancer cell lines of different tissues, including pancreas, breast, skin, and lung were used, as well as chronic lymphocytic leukemia (CLL) patients with different TP53 gene status. The effects of mutant p53 were evaluated by confocal microscopy, reactive oxygen species production assay, immunoblotting, and quantitative reverse transcription polymerase chain reaction after cellular transfection. RESULTS: We demonstrate that oncogenic mutant p53 isoforms are able to inhibit SESN1 expression and consequently the amount of SESN1/AMPK complex, resulting in the downregulation of the AMPK/PGC-1α/UCP2 axis and mitochondrial O2-· production. We also show a correlation between the decrease of reduced thiols with a poorer clinical outcome of CLL patients bearing mutant TP53 gene. The restoration of the mitochondrial uncoupling protein 2 (UCP2) expression, as well as the addition of the radical scavenger N-acetyl-L-cysteine, reversed the oncogenic effects of mutant p53 as cellular hyper-proliferation, antiapoptotic effect, and resistance to drugs. CONCLUSIONS: The inhibition of the SESN1/AMPK/PGC-1α/UCP2 axis contributes to the pro-oxidant and oncogenic effects of mutant p53, suggesting pro-oxidant drugs as a therapeutic approach for cancer patients bearing mutant TP53 gene.