5-Fluorouracil induces apoptosis in rat cardiocytes through intracellular oxidative stress

Exercise-induced cytosolic calcium oscillations: mechanisms and modulation of T-cell function

This study investigated time-dependent changes in intracellular Ca2⁺ levels in T cells, regulatory mechanisms, and functional effects after acute exercise. Male C57BL/6 mice were assigned to control and exercise groups, with the latter sacrificed at different intervals post-exercise. Murine splenic lymphocytes were isolated, and cytosolic Ca2⁺ levels were measured using Fluo-3/AM. T-cell proliferation was assessed by flow cytometry and CFSE labeling, apoptosis by Annexin V/PI staining, and cytokine levels by CBA. RNA sequencing results were validated by qRT-PCR. The findings revealed that exercise significantly altered intracellular calcium oscillations in CD3+ cells, leading to reduced mitogen-stimulated proliferation, increased IL-6, IL-5, and IL-13 production, and decreased IL-2 secretion. Additionally, there was an increase in the apoptotic fraction of CD3+ cells, with upregulated expression of Cav1.1, Cav3.2, Cav3.3, SERCA2B, PKCθ, Bcl-xL, and FADD, and downregulated Ryr3 (p < 0.05). Transcriptomic analysis identified 607 differentially expressed genes involved in calcium ion binding and related pathways, including calcium signaling and cytokine-cytokine receptor interactions. Thus, acute exercise induces specific calcium oscillation patterns in T cells, mediated by PKCθ, affecting proliferation, apoptosis, and cytokine production. These changes are attributed to increased calcium influx through Cav1.1, Cav3.2, and Cav3.3 channels, decreased calcium reuptake via SERCA2B, and reduced calcium release through Ryr3. This research provides novel insights into how exercise modulates immune cell function by altering calcium levels, potential implications for enhancing immune responses or reducing inflammation.

Cardiotoxicity Associated With a Low Doses of 5-FU Promotes Morphoquantitative Changes in the Intrinsic Cardiac Nervous System

5-Fluorouracil (5-FU) is a chemotherapeutic that is used to treat solid tumors. However, 5-FU is associated with several side effects, including cardiotoxicity. Considering the importance of the intrinsic cardiac nervous system (ICNS) for the heart and that little is known about effects of 5-FU on this nervous system plexus, the purpose of the present study was to evaluate effects 5-FU at a low dose on the ICNS and oxidative and inflammatory effects in the heart in Wistar rats. The rats were divided into two groups: treated and 5-FU (n = 6/group). The control group received saline only. The treated group received the following clinical doses of 5-FU: 15 mg/kg for 4 consecutive days, followed by 6 mg/kg for 4 days alternated with non-treatment days, and finally 15 mg/kg as the last dose on day 14. On day 15, the rats were euthanized and underwent thoracotomy. The atria were used for histological analysis, and the ventricles were used for biochemical analysis. The results showed an increase in neuronal density and a decrease in ganglionic and neuronal area in the ICNS. Furthermore, tissue inflammation was observed, indicated by an increase in proinflammatory factors and the enzymatic activity of myeloperoxidase and n-acetyl-glucosaminidase. Oxidative stress was also observed, confirmed by a reduction of endogenous antioxidant defenses and the presence of lipoperoxidation. Treatment with 5-FU also caused cardiac atrophy and fibrosis. These findings indicate that cardiotoxicity is present with 5-FU treatment and affects the morphometric aspects of the ICNS.

A novel approach to the prevention and management of chemotherapy-induced cardiotoxicity: PANoptosis

As a fundamental component of antitumor therapy, chemotherapy-induced cardiotoxicity (CIC) has emerged as a leading cause of long-term mortality in patients with malignant tumors. Unfortunately, there are currently no effective therapeutic preventive or treatment strategies, and the underlying pathophysiological mechanisms of CIC remain inadequately understood. A growing number of studies have shown that different mechanisms of cell death, such as apoptosis, pyroptosis, and necroptosis, are essential for facilitating the cardiotoxic effects of chemotherapy. The PANoptosis mode represents a highly synchronized and dynamically balanced programmed cell death (PCD) process that integrates the principal molecular characteristics of necroptosis, apoptosis, and pyroptosis. Recent research has revealed a significant correlation between PANoptosis and the apoptosis of tumor cells. Chemotherapy drugs can activate PANoptosis, which is involved in the development of cardiovascular diseases. These findings suggest that PANoptosis marks the point where the effectiveness of chemotherapy against tumors overlaps with the onset and development of cardiovascular diseases. Furthermore, previous studies have demonstrated that CIC can simultaneously induce pyrodeath, apoptosis, and necrotic apoptosis. Therefore, PANoptosis may represent a potential mechanism and target for the prevention of CIC. This study explored the interactions among the three main mechanisms of PCD, pyroptosis, apoptosis, and necroptosis in CICs and analyzed the relevant literature on PANoptosis and CICs. The purpose of this work is to serve as a reference for future investigations on the role of PANoptosis in the development and mitigation of cardiotoxicity associated with chemotherapy.

Taxifolin Protects Against 5-Fluorouracil-Induced Cardiotoxicity in Mice Through Mitigating Oxidative Stress, Inflammation, and Apoptosis: Possible Involvement of Sirt1/Nrf2/HO-1 Signaling

Although 5-fluorouracil (5-FU) is widely utilized in cancer treatment, its side effects, including cardiotoxicity, limit its use. Taxifolin (TAX) is a bioactive anti-inflammatory and antioxidant flavonoid. This study aimed to elucidate the protective effect of TAX against 5-FU-induced cardiac injury in male mice. Mice were treated with TAX (25 and 50 mg/kg, orally) for 10 days and a single dose of 150 mg/kg 5-FU at day 8. Mice intoxicated with 5-FU showed increased creatine kinase-MB and lactate dehydrogenase activities and troponin I levels, with multiple cardiac histopathological changes. They also showed a significant increase in cardiac malondialdehyde (MDA) and nitric oxide (NO) and decreases in myocardial reduced glutathione (GSH) content and superoxide dismutase (SOD) and catalase (CAT) activities (P < 0.001). Pretreatment of 5-FU-injected mice with TAX suppressed cardiac injury, decreased MDA and NO contents (P < 0.001), and boosted antioxidant defenses in the myocardium. Moreover, TAX attenuated cardiac inflammatory response, as evidenced by the decreased expression levels of cardiac NF-κB p65, inducible nitric oxide synthase (iNOS), and pro-inflammatory cytokines (P < 0.001). Largely, TAX ameliorated the decrease in Bcl-2 expression and the increase in BAX and caspase-3 in the heart. It also restored the cardiac Sirt1/Nrf2/HO-1 signaling pathway. In conclusion, TAX showed significant cardioprotective effects on 5-FU-induced cardiac injury and might represent a promising adjuvant in preventing cardiac injury associated with oxidative stress and inflammation.

Esterase-Responsive Self-Immolative Prodrugs for the Sustained Delivery of the Anticancer Drug 5-Fluorouracil with Turn-On Fluorescence

Stimuli-responsive prodrugs of anticancer drugs are advantageous for the selective delivery of drugs to cancer cells with minimized off-target side effects. In the present study, esterase-activatable fluorogenic prodrugs of the chemotherapeutic drug 5-fluorouracil (5-FU) have been rationally designed and synthesized using multi-step organic synthesis. While 5-FU was connected directly with the fluorophore via a C-N bond in the prodrug BJ-50, an additional self-immolative benzylic spacer with a carbonate linker was incorporated in the prodrug BJ-92. Although absorption and emission spectroscopic studies revealed the activation of both the prodrugs by porcine liver esterase (PLE), reverse-phase HPLC studies confirmed the inability of BJ-50 to release the active drug 5-FU. In contrast, a sustained release of 5-FU and Cou-OH was observed from BJ-92 in the presence of PLE. The endogenous esterase-mediated activation of the prodrug BJ-92 was validated by the turn-on fluorescence in A549 cells and the anti-proliferative activities in A549, and HEK-293 cells. Modulation of the expression of a few cancer marker proteins by BJ-92 and 5-FU was studied to evaluate their anticancer activities. As esterases are overexpressed in cancer cells, the prodrug in the present study would be helpful in selectively delivering 5-FU to cancer cells with reduced off-target side-effects.

Cardiometabolic benefits of fenofibrate in heart failure related to obesity and diabetes

BACKGROUND

Heart failure (HF) is a serious and common condition affecting millions of people worldwide, with obesity being a major cause of metabolic disorders such as diabetes and cardiovascular disease. This study aimed to investigate the effects of fenofibrate, a peroxisome proliferator-activated receptor alpha (PPARα) agonist, on the obese- and diabetes-related cardiomyopathy.

METHODS AND RESULTS

We used db/db mice and high fat diet-streptozotocin induced diabetic mice to investigate the underlying mechanisms of fenofibrate's beneficial effects on heart function. Fenofibrate reduced fibrosis, and lipid accumulation, and suppressed inflammatory and immunological responses in the heart via TNF signaling. In addition, we investigated the beneficial effects of fenofibrate on HF hospitalization. The Korean National Health Insurance database was used to identify 427,154 fenofibrate users and 427,154 non-users for comparison. During the 4.22-year follow-up, fenofibrate use significantly reduced the risk of HF hospitalization (hazard ratio, 0.907; 95% CI 0.824-0.998).

CONCLUSIONS

The findings suggest that fenofibrate may be a useful therapeutic agent for obesity- and diabetes-related cardiomyopathy.

Resveratrol as a cardioprotective adjuvant for 5-fluorouracil in the treatment of gastric cancer cells

The clinical application of 5-fluorouracil (5-Fu), a potent chemotherapeutic agent, is often hindered by its well-documented cardiotoxic effects. Nevertheless, natural polyphenolic compounds like resveratrol (RES), known for their dual anti-tumor and cardioprotective properties, are potential adjunct therapeutic agents. In this investigation, we examined the combined utilization of RES and 5-Fu for the inhibition of gastric cancer using both in vitro and in vivo models, as well as their combined impact on cardiac cytotoxicity. Our study revealed that the co-administration of RES and 5-Fu effectively suppressed MFC cell viability, migration, and invasion, while also reducing tumor weight and volume. Mechanistically, the combined treatment prompted p53-mediated apoptosis and autophagy, leading to a considerable anti-tumor effect. Notably, RES mitigated the heightened oxidative stress induced by 5-Fu in cardiomyocytes, suppressed p53 and Bax expression, and elevated Bcl-2 levels. This favorable influence enhanced primary cardiomyocyte viability, decreased apoptosis and autophagy, and mitigated 5-Fu-induced cardiotoxicity. In summary, our findings suggested that RES holds promise as an adjunct therapy to enhance the efficacy of gastric cancer treatment in combination with 5-Fu, while simultaneously mitigating cardiotoxicity.

Apoptotic effect of 5-fluorouracil-doxorubicin combination on colorectal cancer cell monolayers and spheroids

BACKGROUND

Drug combination studies help to improve new treatment approaches for colon cancer. Tumor spheroids (3D) are better models than traditional 2-dimensional cultures (2D) to evaluate cellular responses to chemotherapy drugs. The cultivation of cancer cells in 2D and 3D cultures affects the apoptotic process, which is a major factor influencing the response of cancer cells to chemotherapeutic drugs. In this study, the antiproliferative effects of 5-fluorouracil (5-FU) and doxorubicin (DOX) were investigated separately and in combination using 2D and 3D cell culture models on two different colon cancer cell lines, HT-29 (apoptosis-resistant cells) and Caco-2 2 (apoptosis-susceptible cells).

METHODS

The effect of the drugs on the proliferation of both colon cancer cells was determined by performing an MTT assay in 2D culture. The apoptotic effect of 5-FU and DOX, both as single agents and in combination, was assessed in 2D and 3D cultures through quantitative real-time polymerase chain reaction analysis. The expression of apoptotic genes, such as caspases, p53, Bax, and Bcl-2, was quantified.

RESULTS

It was found that the mRNA expression of proapoptotic genes was significantly upregulated, whereas the mRNA expression of the antiapoptotic Bcl-2 gene was significantly downregulated in both colon cancer models treated with 5-FU, DOX, and 5-FU + DOX.

CONCLUSION

The results indicated that the 5-FU + DOX combination therapy induces apoptosis and renders 5-FU and DOX more effective at lower concentrations compared to their alone use. This study reveals promising results in reducing the potential side effects of treatment by enabling the use of lower drug doses.

α-Hederin induces paraptosis by targeting GPCRs to activate Ca2+/MAPK signaling pathway in colorectal cancer

BACKGROUND

Non-apoptotic cell death is presently emerging as a potential direction to overcome the apoptosis resistance of cancer cells. In the current study, a natural plant agent α-hederin (α-hed) induces caspase-independent paraptotic modes of cell death.

PURPOSE

The present study is aimed to investigate the role of α-hed induces paraptosis and the associated mechanism of it.

METHODS

The cell proliferation was detected by CCK-8. The cytoplasm organelles were observed under electron microscope. Calcium (Ca2+) level was detected by flow cytometry. Swiss Target Prediction tool analyzed the potential molecule targets of α-hed. Molecular docking methods were used to evaluate binding abilities of α-hed with targets. The expressions of genes and proteins were analyzed by RT-qPCR, western blotting, immunofluorescence, and immunohistochemistry. Xenograft models in nude mice were established to evaluate the anticancer effects in vivo.

RESULTS

α-hed exerted significant cytotoxicity against a panel of CRC cell lines by inhibiting proliferation. Besides, it induced cytoplasmic vacuolation in all CRC cells. Electron microscopy images showed the aberrant dilation of endoplasmic reticulum and mitochondria. Both mRNA and protein expressions of Alg-2 interacting proteinX (Alix), the marker of paraptosis, were inhibited by α-hed. Besides, both Swiss prediction and molecular docking showed that the structure of α-hed could tightly target to GPCRs. GPCRs were reported to activate the phospholipase C (PLC)-β3/ inositol 1,4,5-trisphosphate receptor (IP3R)/ Ca2+/ protein kinase C alpha (PKCα) pathway, and we then found all proteins and mRNA expressions of PLCβ3, IP3R, and PKCα were increased by α-hed. After blocking the GPCR signaling, α-hed could not elevate Ca2+ level and showed less CRC cell cytotoxicity. MAPK cascade is the symbol of paraptosis, and we then demonstrated that α-hed activated MAPK cascade by elevating Ca2+ flux. Since non-apoptotic cell death is presently emerging as a potential direction to overcome chemo-drug resistance, we then found α-hed also induced paraptosis in 5-fluorouracil-resistant (5-FU-R) CRC cells, and it reduced the growth of 5-FU-R CRC xenografts.

CONCLUSIONS

Collectively, our findings proved α-hed as a promising candidate for inducing non-apoptotic cell death, paraptosis. It may overcome the resistance of apoptotic-based chemo-resistance in CRC.

Identifying metabolic adaptations characteristic of cardiotoxicity using paired transcriptomics and metabolomics data integrated with a computational model of heart metabolism

Improvements in the diagnosis and treatment of cancer have revealed long-term side effects of chemotherapeutics, particularly cardiotoxicity. Here, we present paired transcriptomics and metabolomics data characterizing in vitro cardiotoxicity to three compounds: 5-fluorouracil, acetaminophen, and doxorubicin. Standard gene enrichment and metabolomics approaches identify some commonly affected pathways and metabolites but are not able to readily identify metabolic adaptations in response to cardiotoxicity. The paired data was integrated with a genome-scale metabolic network reconstruction of the heart to identify shifted metabolic functions, unique metabolic reactions, and changes in flux in metabolic reactions in response to these compounds. Using this approach, we confirm previously seen changes in the p53 pathway by doxorubicin and RNA synthesis by 5-fluorouracil, we find evidence for an increase in phospholipid metabolism in response to acetaminophen, and we see a shift in central carbon metabolism suggesting an increase in metabolic demand after treatment with doxorubicin and 5-fluorouracil.

Targeted magnetochemotherapy modified by 5-Fu-loaded thermally on/off switching nanoheaters for the eradication of CT26 murine colon cancer by inducing apoptotic and autophagic cell death

Despite significant breakthroughs in diagnosis and treatment of colorectal cancer (CRC), the extent of morbidity and mortality secondary to CRC is still concerning. In this study, we evaluated the efficacy of our new tumor-selective nanoplatforms at induction of apoptosis and autophagy, which was tested using active 5-fluorouracil (5-Fu)-based targeting of tumor cells in a BALB/c murine model of CRC combined with magnetic thermal therapy. Nanoparticles were synthesized and characterized by zeta sizer, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The cytotoxicity and tissue uptake of 5-Fu-loaded folic acid (Fa)-modified magnetic nanoparticles (5-Fu/MNPs-Fa) was assessed using MTT, ICP-OES, and HPLC. The rate of apoptosis and autophagy, as two major indicators of antitumor activity, was measured based on protein expression of Bax, Bcl2, Caspase 3, mTOR, P-mTOR, Beclin-1, and LC3B in CT-26 murine CRC, along with tumor volume and survival time. The spherical 5-Fu/MNPs-Fa exhibited sustained thermal on/off switching drug release and higher therapeutic index compared to free 5-Fu. Our de novo synthetized magnetic nanoheaters successfully delivered the therapeutic agent to the tumor site, enhanced the conversion of radio frequency energy to heat in tumor cells, exhibited higher antitumor efficiency based on Bax/Bcl2 ratio and overexpression of Beclin-1 and LC3B, increased the survival time, and decreased the tumor volume (P < 0.05). Our findings indicated that magnetochemotherapy (MHC) was substantially more effective than hyperthermia and/or chemotherapy alone. From a translational standpoint, the 5-Fu/MNPs-Fa would be a promising candidate sustained drug targeting system that could improve cancer cell therapy via inducing apoptosis and autophagy.

Graphical Abstract

Acetylation of aldehyde dehydrogenase ALDH1L2 regulates cellular redox balance and the chemosensitivity of colorectal cancer to 5-fluorouracil

Folate-mediated one-carbon metabolism (FOCM) is crucial in sustaining rapid proliferation and survival of cancer cells. The folate cycle depends on a series of key cellular enzymes, including aldehyde dehydrogenase 1 family member L2 (ALDH1L2) that is usually overexpressed in cancer cells, but the regulatory mechanism of ALDH1L2 remains undefined. In this study, we observed the significant overexpression of ALDH1L2 in colorectal cancer (CRC) tissues, which is associated with poor prognosis. Mechanistically, we identified that the acetylation of ALDH1L2 at the K70 site is an important regulatory mechanism inhibiting the enzymatic activity of ALDH1L2 and disturbing cellular redox balance. Moreover, we revealed that sirtuins 3 (SIRT3) directly binds and deacetylates ALDH1L2 to increase its activity. Interestingly, the chemotherapeutic agent 5-fluorouracil (5-Fu) inhibits the expression of SIRT3 and increases the acetylation levels of ALDH1L2 in colorectal cancer cells. 5-Fu-induced ALDH1L2 acetylation sufficiently inhibits its enzymatic activity and the production of NADPH and GSH, thereby leading to oxidative stress-induced apoptosis and suppressing tumor growth in mice. Furthermore, the K70Q mutant of ALDH1L2 sensitizes cancer cells to 5-Fu both in vitro and in vivo through perturbing cellular redox and serine metabolism. Our findings reveal an unknown 5-Fu-SIRT3-ALDH1L2 axis regulating redox homeostasis, and suggest that targeting ALDH1L2 is a promising therapeutic strategy to sensitize tumor cells to chemotherapeutic agents.

Artesunate alleviates 5-fluorouracil-induced intestinal damage by suppressing cellular senescence and enhances its antitumor activity

BACKGROUND

Colorectal cancer (CRC) is one of the most prevalent diagnosed malignancies and one of the leading causes of cancer-related deaths worldwide. 5-Fluorouracil (5-FU) and its combination regimen are commonly used as primary chemotherapeutic agents for advanced CRC. Intestinal mucositis is one of the most frequent side effects of 5-FU. Artesunate (Arte) is derived from the wormwood plant Artemisia annua. Arte is not only effective against malaria but also diabetes, atherosclerosis, inflammation, and other conditions. The mechanism by which 5-FU damages the intestinal tract is unclear, and there is no standard treatment for diarrhea caused by 5-FU. Therefore, it is critical to discover novel and promising therapeutic drugs for 5-FU side effect treatment.

METHODS

The morphology and expression of genes and proteins associated with the aging of HUVECs, HIECs, and intestinal tissues were compared to the those of the control group. The cell lines and tissues were evaluated by SA-β-Gal staining, Western blotting, and RT‒qPCR. HIEC and HCT116 cell viability was assessed in vitro by a CCK-8 assay and in vivo by a subcutaneous tumor mouse assay. Tumor cell proliferation and apoptosis was evaluated by immunohistochemistry.

RESULTS

Here, we report that Arte alleviates the adverse side effects caused by 5-FU in intestinal tissue, and that 5-FU-induced intestinal damage is associated with drug-induced chemical inflammation and an increase in the proportion of senescent cells. Arte decreases the ratio of SA-β-Gal-positive cells and downregulated the expression of aging-related proteins (p53, p16) and aging-related genes (p53, p21). Mechanistically, Arte relieves intestinal injury by inhibiting mTOR expression, which is associated with the regulation of aging. Moreover, Arte suppresses the p38MAPK and NF-κB signaling pathways, which are related to inflammation regulation. In addition, the combined therapy of Arte plus 5-FU significantly decreases cancer cell viability in vitro. Arte and 5-FU synergistically reduce the growth of colorectal cancer (CRC) xenografts in vivo.

CONCLUSIONS

Overall, our findings point to the crucial treatment effect of Arte on inflammation, intestinal cell senescence, and CRC cell proliferation and offer a new option for CRC treatment.

Sinapic acid alleviates 5-fluorouracil-induced nephrotoxicity in rats via Nrf2/HO-1 signalling

Fluoropyrimidine 5-fluorouracil (5-FU) is a DNA analogue broadly used in chemotherapy, though treatment-associated nephrotoxicity limits its widespread clinical use. Sinapic acid (SA) has potent antioxidant, anti-inflammatory, and anti-apoptotic effects, we investigated its protective effects against 5-FU-induced nephrotoxicity in a rat model. We designated four treatment groups each Group I (control) received five intraperitoneal saline injections (once daily) from days 17 to 21; Group II received five intraperitoneal injections of 5-FU (50 mg/kg/day) from days 17 to 21; Group III received an oral administration of SA (40 mg/kg) for 21 days and five intraperitoneal injections of 5-FU (50 mg/kg/day) from days 17 to 21; and Group IV received an oral administration of SA (40 mg/kg) for 21 days (n-six rats in each group). blood samples were collected on day 22 from each group. Animals were sacrificed and their kidneys removed, and instantly frozen. 5-FU caused oxidative stress, inflammation, and activation of the apoptotic pathway by upregulating Bax and Caspase-3 and downregulating Bcl-2. However, SA exposure reduced serum toxicity indicators, boosted antioxidant defences, and reduced kidney apoptosis, which was confirmed by histopathological analysis. Therefore, prophylactic administration of SA could inhibit 5-FU-induced renal injuries in rats via suppression of renal inflammation and oxidative stress, primarily through regulation of NF-κB and proinflammatory cytokines, inhibition of renal apoptosis, and restoration of tubular epithelial antioxidant activities and cytoprotective defences.

An integrative review of nonobvious puzzles of cellular and molecular cardiooncology

Oncologic patients are subjected to four major treatment types: surgery, radiotherapy, chemotherapy, and immunotherapy. All nonsurgical forms of cancer management are known to potentially violate the structural and functional integrity of the cardiovascular system. The prevalence and severity of cardiotoxicity and vascular abnormalities led to the emergence of a clinical subdiscipline, called cardiooncology. This relatively new, but rapidly expanding area of knowledge, primarily focuses on clinical observations linking the adverse effects of cancer therapy with deteriorated quality of life of cancer survivors and their increased morbidity and mortality. Cellular and molecular determinants of these relations are far less understood, mainly because of several unsolved paths and contradicting findings in the literature. In this article, we provide a comprehensive view of the cellular and molecular etiology of cardiooncology. We pay particular attention to various intracellular processes that arise in cardiomyocytes, vascular endothelial cells, and smooth muscle cells treated in experimentally-controlled conditions in vitro and in vivo with ionizing radiation and drugs representing diverse modes of anti-cancer activity.

Naringin ameliorates 5-fluorouracil induced cardiotoxicity: An insight into its modulatory impact on oxidative stress, inflammatory and apoptotic parameters

5-fluorouracil (5-FU) is an efficacious fluoropyrimidine antimetabolite anticancer drug, however, its clinical utility is constrained due to side effect toxicity on delicate organs, including the heart. This study thus aimed at exploring the cardioprotective potentials of naringin (NRG) against 5-FU-induced cardiotoxicity in rats. We divided Wistar rats into four experimental groups (n = 6) for the administration of NRG (100 mg/kg bw, orally) and/or 5-FU (150 mg/kg bw, intraperitoneal). NRG was administered for 10 days, while 5-FU was injected on the 8th day only. Serum troponin-I (cTn-I) and creatine kinase (CK) were estimated. Cardiac activities/level of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), reduced glutathione (GSH), malondialdehyde (MDA), interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase (iNOS) and nuclear factor-ĸB (NF-κB) and caspase-3 were determined. 5-FU markedly increased cTn-I, CK, cardiac inflammatory mediators and caspase-3 expressions, whereas antioxidant mediators decreased appreciably when compared to the control groups. Interestingly, the prophylactic administration of NRG prominently inhibited the 5-FU-provoked oxidative stress, pro-inflammation and apoptosis in the heart of rats. Histopathology confirmed the biochemical results of the heart. Therefore, NRG is a potential natural flavonoid for mitigation of 5-FU cardiotoxicity in rats.

Exploring the cardioprotective effects of canagliflozin against cisplatin-induced cardiotoxicity: Role of iNOS/NF-κB, Nrf2, and Bax/cytochrome C/Bcl-2 signals

Cardiotoxicity is a severe considerable side effect of cisplatin (CDDP) that requires much medical attention. The current study investigates the cardioprotective effects of canagliflozin (CA) against CDDP-induced heart toxicity. Rats were allocated to the control group; the CA group was administered CA 10 mg/kg/day orally for 10 days; the CDDP group was injected with 7 mg/kg, intraperitoneal as a single dose on the 5th day, and the CDDP + CA group. Compared to the CDDP-treated group, CA effectively attenuated CDDP-induced heart injury as evidenced by a decrease of serum aspartate aminotransferase, alkaline phosphatase, creatine kinase-MB, and lactate dehydrogenase enzymes and supported by the alleviation of histopathological changes in cardiac tissues. Biochemically, CA attenuated cardiac oxidative injury through upregulation of the nuclear factor-erythroid 2 related factor 2 (Nrf2) signal. CA suppressed inflammation by decreasing cardiac NO₂ ^- , MPO, iNOS, nuclear factor kappa B (NF-κB), tumor necrosis factor-alpha, and interleukin 1-beta levels. Besides, CA significantly upregulated cardiac levels of phosphoinositide 3-kinase (PI3K), protein kinase B (AKT), and p-AKT proteins. Moreover, CA remarkably mitigated CDDP-induced apoptosis via modulation of Bax, cytochrome C, and Bcl-2 protein levels. Together, the present study revealed that CA could be a good candidate for preventing CDDP-induced cardiac injury by modulating iNOS/NF-κB, Nrf2, PI3K/AKT, and Bax/cytochrome C/Bcl-2 signals.

Thiolated pectin-chitosan composites: Potential mucoadhesive drug delivery system with selective cytotoxicity towards colorectal cancer

Mucoadhesive drug delivery systems (DDS) may promote safer chemotherapy for colorectal cancer (CRC) by maximizing local drug distribution and residence time. Carbohydrate polymers, e.g. pectin (P) and chitosan (CS), are potential biomaterials for CRC-targeted DDS due to their gelling ability, mucoadhesive property, colonic digestibility, and anticancer activity. Polymer mucoadhesion is augmentable by thiolation, e.g. pectin to thiolated pectin (TP). Meanwhile, P-CS polyelectrolyte complex has been shown to improve structural stability. Herein, we fabricated, characterized, and evaluated 5-fluorouracil-loaded primary DDS combining TP and CS as a composite (TPCF) through triple crosslinking actions (calcium pectinate, polyelectrolyte complex, disulfide). Combination of these crosslinking yields superior mucoadhesion property relative to single- or dual-crosslinked counterparts, with comparable drug release profile and drug compatibility. PCF and TPCF exhibited targeted cytotoxicity towards HT29 CRC cells with milder cytotoxicity towards HEK293 normal cells. In conclusion, TP-CS composites are promising next-generation mucoadhesive and selectively cytotoxic biomaterials for CRC-targeted DDS.

Cardioprotective effect of silymarin nanoemulsion on 5-fluorouracil-induced cardiotoxicity in rats

5-Fluorouracil (5-FU)-associated cardiotoxicity has been ranked as the second most common cause of cardiotoxicity induced by chemotherapeutic drugs after anthracyclines. In the present study, we investigated the protective impacts of silymarin (SIL) and silymarin nanoemulsion (SLN) against cardiotoxicity caused by 5-FU in rats. Thirty male Wistar rats were divided into six groups as follows: control, SLN (5 mg/kg), SIL (5 mg/kg), 5-FU + SLN, 5-FU + SIL, and 5-FU. Cardiotoxicity was induced by a single intraperitoneal injection of 5-FU (100 mg/kg). The control group received an intraperitoneal injection (ip) of normal saline and the treatment groups received ips of SIL and SLN for 14 days. 5-FU resulted in significant cardiotoxicity, represented by an increase in the serum levels of cardiac enzymes and malondialdehyde, as well as cyclooxygenase-2 (COX-2) and tumor necrosis factor-α (TNF-α) expression, and histopathological degeneration. 5-FU treatment also induced a decrease in body weight, total antioxidant capacity (TAC), and catalase values. Evaluation of electrocardiographic parameters in 5-FU-treated rats showed increases in the ST segment, QRS duration, and RR interval. Treatment with SIL and SLN reduced oxidative stress, cardiac enzymes, histopathological degeneration, and the expression of TNF-α and COX-2 in cardiac tissue. Our results demonstrated that treatment with SIL and SLN significantly improved cardiotoxicity induced by 5-FU in rats.

MOF-801 as a Nanoporous Water-Based Carrier System for In Situ Encapsulation and Sustained Release of 5-FU for Effective Cancer Therapy

Nanoporous metal-organic frameworks (MOFs) have been gaining a reputation for their drug delivery applications. In the current work, MOF-801 was successfully prepared by a facile, cost-efficient, and environmentally friendly approach through the reaction of ZrCl₄ and fumaric acid as organic linkers to deliver 5-fluorouracil (5-FU). The prepared nanostructure was fully characterized by a series of analytical techniques including Fourier transform infrared spectroscopy, powder X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, UV-vis spectroscopy, ¹H NMR spectroscopy, thermogravimetric analysis, high-performance liquid chromatography, and Brunauer-Emmett-Teller analysis. MOF-801 could be used for the delivery of the anticancer drug 5-FU due to its high surface area, suitable pore size, and biocompatible ingredients. Based on in vitro loading and release studies, a high 5-FU loading capacity and pH-dependent drug release behavior were observed. Moreover, the interactions between the structure of MOFs and 5-FU were investigated through Monte Carlo simulation calculations. An in vitro cytotoxicity test was done, and the results indicated that 5-FU@MOF-801 was more potent than 5-FU on SW480 cancerous cells, indicating the highlighted role of this drug delivery system. Finally, the kinetics of drug release was investigated.

Cardiac Toxicity From Adjuvant Targeting Treatment for Breast Cancer Post-Surgery

Breast cancer is one of the most prevalent types of cancers worldwide, especially for females. Surgery is the preferred treatment for breast cancer, and various postoperative adjuvant therapies can be reasonably used according to different pathological characteristics, especially traditional radiotherapy, chemotherapy, and endocrine therapy. In recent years, targeting agent therapy has also become one of the selective breast cancer treatment strategies, including anti-HER-2 drugs, CDK4/6 inhibitor, poly ADP-ribose polymerase inhibitor, PI3K/AKT/mTOR pathway inhibitor, ER targeting drugs, and aromatase inhibitor. Because of the different pathologic mechanisms of these adjuvant therapies, each of the strategies may cause cardiotoxicity in clinic. The cardiac adverse events of traditional endocrine therapy, radiotherapy, and chemotherapy for breast cancer have been widely detected in clinic; however, the targeting therapy agents have been paid more attention with the extension of application. This review will summarize the cardiac toxicity of various adjuvant therapies for breast cancer, especially for targeting drug therapy.

Myricetin (3,3',4',5,5',7-Hexahydroxyflavone) Prevents 5-Fluorouracil-Induced Cardiotoxicity

5-Fluorouracil (5-FU) is a strong anti-cancer drug used to manage numerous cancers. Cardiotoxicity, renal toxicity, and liver toxicity are some of the adverse effects which confine its clinical use to some extent. 5-FU-induced organ injuries are associated with redox imbalance, inflammation, and damage to heart functioning, particularly in the present study. Myricetin is an abundant flavonoid, commonly extracted from berries and herbs having anti-oxidative and anti-cancer activities. We planned the current work to explore the beneficial effects of myricetin against 5-FU-induced cardiac injury in Wistar rats through a biochemical and histological approach. Prophylactic myricetin treatment at two doses (25 and 50 mg/kg) was given to rats orally for 21 days against cardiac injury induced by a single injection of 5-FU (150 mg/kg b.wt.) given on the 20th day intraperitoneally. The 5-FU injection induced oxidative stress, inflammation, and extensive cardiac damage. Nevertheless, myricetin alleviated markers of inflammation, apoptosis, cardiac toxicity, oxidative stress, and upregulated anti-oxidative machinery. The histology of heart further supports our biochemical findings mitigated by the prophylactic treatment of myricetin. Henceforth, myricetin mitigates 5-FU-induced cardiac damage by modulating oxidative stress, inflammation, and cardiac-specific markers, as found in the present study.

Colchicine Ameliorates 5-Fluorouracil-Induced Cardiotoxicity in Rats

Background and Objective. 5-Fluorouracil is one of the most common chemotherapeutic agents used in the treatment of solid tumors. 5-Fluorouracil-associated cardiotoxicity is the second cause of cardiotoxicity induced by chemotherapeutic drugs after anthracyclines. Colchicine is a strong anti-inflammatory drug used to prevent and treat acute gout and treat familial Mediterranean fever. And also, its protective effects on cardiovascular disease have been reported in various studies. The current study is aimed at appraising the effect of colchicine on 5-fluorouracil-induced cardiotoxicity in rats. Methods. Twenty male Wistar rats were divided into four groups as follows: control, 5-fluorouracil, colchicine (5 mg/kg), and 5-fluorouracil+5 mg/kg colchicine. Cardiotoxicity was induced with an intraperitoneal injection of a single dose of 5-fluorouracil (100 mg/kg). The control group received normal saline, and the treatment groups received colchicine with an intraperitoneal injection for 14 days. Findings. 5-Fluorouracil resulted in significant cardiotoxicity represented by an increase in cardiac enzymes, malondialdehyde levels, cyclooxygenase-2 and tumor necrosis factor-alpha expression, cardiac enzymes, and histopathological degenerations. 5-Fluorouracil treatment also decreased body weight, total antioxidant capacity and catalase values, blood cells, and hemoglobin levels. In addition, 5-fluorouracil disrupted electrocardiographic parameters, including increased elevation in the ST segment and increased QRS duration. Treatment with colchicine reduced oxidative stress, cardiac enzymes, histopathological degenerations, and cyclooxygenase-2 expression in cardiac tissue, improved electrocardiographic disorders, and enhanced the number of blood cells and total antioxidant capacity levels. Moreover, body weight loss was hampered after treatment with colchicine. Our results demonstrated that treatment with colchicine significantly improved cardiotoxicity induced by 5-fluorouracil in rats.

Managing 5FU Cardiotoxicity in Colorectal Cancer Treatment

Fluorouracil (5FU) is the backbone chemotherapy agent in the treatment of colorectal cancer (CRC). Cardiotoxicity represents an uncommon but serious side effect of treatment with 5FU. Here, we review the current literature on 5FU-cardiotoxicity in the setting of CRC specifically, with a focus on data from the modern era of combination chemotherapy. Despite decades of study, there is little consensus on risk factors and biomarkers for 5FU-cardiotoxicity, nor how patients with CRC should be managed following a cardiotoxicity event. Given the elevated risk of recurrent cardiotoxicity on rechallenge, the use of alternative regimens that do not contain 5FU is a critical aspect of management. Data on the cardiotoxicity risk and efficacy of non-5FU regimens in CRC are therefore reviewed in detail.

Dynamic observation of 5-fluorouracil-induced myocardial injury and mitochondrial autophagy in aging rats

Patients treated with 5-fluorouracil (5-FU) can develop rare but potentially severe cardiac effects, including cardiomyopathy, angina pectoris, heart failure and cardiogenic shock. The specific pathologies and underlying mechanisms are yet to be fully understood. The results of previous studies have indicated that mitochondrial autophagy is widely detected in many angiocardiopathies. In the present study, the dynamic changes in the homeostasis of mitochondrial injury and autophagy were observed in rats treated with 5-FU for different durations. A corresponding control group and a 5-FU model group were established in groups of Sprague-Dawley rats aged 2 and 18 months, and the myocardial enzyme levels were determined at different time points. At 2 weeks post-model establishment, cardiac ultrasound and myocardial histological staining were performed, cardiomyocyte apoptosis and myocardial mitochondrial function were assessed, and mitochondrial ultrastructure was examined. In addition, the expression levels of autophagy-related proteins were evaluated in the 18-month-old rats on days 7 and 14 of 5-FU administration. The experimental results demonstrated that 5-FU induced an elevation in the levels of myocardial enzymes, as well as changes in the cardiac structure and function, and that these changes were more prominent over longer drug durations. In addition, 5-FU decreased the levels of myocardial mitochondrial ATP and mitochondrial membrane potential, and aggravated myocardial fibrosis and cardiomyocyte apoptosis compared with those observed in the untreated control group, treated with the same volume of saline as 5-FU in the 5-FU group. These injuries were particularly evident in aging rats. Notably, 5-FU increased the expression levels of myocardial mitochondrial autophagy-related proteins, and electron microscopy revealed a more severe autophagic state in the model groups compared with that in the control groups. In conclusion, 5-FU induced myocardial mitochondrial damage, the degree of which was more severe in aging rats compared with that in young rats. The mitochondrial autophagy induced by 5-FU was excessive, and the degree of autophagy was aggravated with increased 5-FU administration time.

Effect of TRPM2-Mediated Calcium Signaling on Cell Proliferation and Apoptosis in Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is the sixth leading cause of death due to cancer, indicating that finding new therapeutic targets or approaches for ESCC treatment is imperative. Transient Receptor Potential cation channel subfamily M, member 2 (TRPM2) is a calcium-permeable, nonselective cation channel that responds to reactive oxygen species (ROS), which are found in the tumor microenvironment and are important regulators of tumorigenesis, cell proliferation, apoptosis, and the therapeutic response. Here, we used immunohistochemical analysis of tumor tissue derived from patients with ESCC to find that the TRPM2 channel protein expression level was increased in tumor tissue compared with adjacent normal tissue. Intracellular calcium concentration measurements, western blotting, and ROS and cell viability assays were used with a human ESCC cell line (TE-1 cells) to find that TRPM2 participated in the ROS hydrogen peroxide-induced increase in intracellular calcium. This increased calcium inhibited cell proliferation and enhanced apoptosis. Pretreatment of cells with the anticancer agent 5-fluorouracil (5-FU) significantly increased ROS production, which potentiated TRPM2-mediated calcium signaling, decreased cell proliferation, and increased apoptosis in TE-1 cells, suggesting that the therapeutic effect of 5-FU in ESCC cells may be mediated by the TRPM2 channel-mediated calcium influx. These findings offer a potential treatment target and provide mechanistic insight into the therapeutic effects of 5-FU in patients with ESCC.

Angelica Polysaccharide Antagonizes 5-FU-Induced Oxidative Stress Injury to Reduce Apoptosis in the Liver Through Nrf2 Pathway

Oxidative stress induced by chemotherapeutic agents causes hepatotoxicity. 5-Fluorouracil (5-FU) has been found to have a variety of side effects, but its toxic effect on the liver and the mechanism are still unclear. Angelica polysaccharide (ASP), the main active ingredient of Dang Gui, has antioxidative stress effects. In this study, we investigated the antagonistic effects of ASP on 5-FU-induced injury in the mouse liver and human normal liver cell line MIHA and the possible mechanism. Our results show that ASP inhibited 5-FU-induced the decrease in Bcl-2 protein and the increase in Bax protein. ASP alleviated 5-FU-induced the increase in alanine aminotransferase (ALT), triglyceride (TG), and aspartate aminotransferase (AST) content; hepatic steatosis; and liver fibrosis. ASP restored 5-FU-induced swelling of mitochondria and the endoplasmic reticulum. 5-FU promoted the expression of Keap1 and increased the binding to NF-E2-related factor 2 (Nrf2) to reduce the nuclear translocation of Nrf2, thereby weakening the transcriptional activity of Nrf2 to inhibit the expression of HO-1; reducing the activity of GSH, SOD, and CAT to increase ROS content; and aggravating DNA damage (indicated by the increase in 8-OHdG). However, ASP reversed these reactions. In conclusion, ASP attenuated the 5-FU-induced Nrf2 pathway barrier to reduce oxidative stress injury and thereby inhibit the disorder of lipid anabolism and apoptosis. The study provides a new protectant for reducing the hepatic toxicity caused by 5-FU and a novel target for treating the liver injury.

Bioactivity Studies of Hesperidin and XAV939

The present work aimed to evaluate the reactivity of natural bioflavonoid hesperidin (HSP) and synthetically derived XAV939 (XAV) against human hepatocellular carcinoma (HepG2), human breast cancer (MDA-MB231) cancer cell lines, and related molecular and pathological profiles. Data recorded revealed that the cytotoxic potential of the tested products was found to be cell type- and concentration-dependent. The half-maximal inhibitory concentration (IC₅₀) value of the HSP-XAV mixture against MDA-MB231 was significantly decreased in the case of using the HSP-XAV mixture against the HepG2 cell line. Also, there was a significant upregulation of the phosphotumor suppressor protein gene (P53) and proapoptotic genes such as B-cell lymphoma-associated X-protein (Bax, CK, and Caspase-3), while antiapoptotic gene B-cell lymphoma (Bcl-2) was significantly downregulated compared with the untreated cell control. The cell cycle analysis demonstrated that DNA accumulation was detected mainly during the G2/M phase of the cell cycle accompanied with the elevated reactive oxygen species level in the treatment of HepG2 and MDA-MB231 cell lines by the HSP-XAV mixture, more significantly than that in the case of cell control. Finally, our finding suggests that both HSP and XAV939 and their mixture may offer an alternative in human liver and breast cancer therapy.

The IL-6/STAT Signaling Pathway and PPARα Are Involved in Mediating the Dose-Dependent Cardioprotective Effects of Fenofibrate in 5-Fluorouracil-Induced Cardiotoxicity

PURPOSE

The cardiotoxicity of anticancer drugs such as 5-fluorouracil (5FU) is a major complication that challenges their clinical usefulness. Thus there is a critical need to find new protective drugs to defend against these harmful side effects. Up to now, there have been no studies evaluating the possible cardioprotective effects of fenofibrate (FEN) in 5FU-induced cardiotoxicity. Therefore, we aimed in the current model to evaluate such an effect of FEN and to explore different mechanisms mediating it.

METHODS

We used FEN (25, 50, 100 mg/kg/day) administered orally for 7 days with induction of cardiotoxicity by intraperitoneal (i.p.) injection of 5FU (150 mg/kg) on the fifth day.

RESULTS

The current study showed that 5FU succeeded in inducing cardiotoxicity, manifested by significantly elevated levels of cardiac enzymes, tissue malondialdehyde (MDA), interleukin 6 (IL-6), signal transducer and activator of transcription 4 (STAT4), and caspase-3. Furthermore, the 5FU group showed toxic histopathological changes including marked cardiac damage and a significant decrease in reduced glutathione (GSH), total antioxidant capacity (TAC), and peroxisome proliferator-activated receptor alpha (PPARα) expression. FEN reversed 5FU-induced cardiotoxicity by various mechanisms including upregulation of PPARα, inhibition of the IL-6/STAT signaling pathway, and anti-inflammatory, antiapoptotic, and antioxidant properties.

CONCLUSION

FEN demonstrated a significant cardioprotective effect against 5FU-induced cardiac damage.

Molecules and Mechanisms to Overcome Oxidative Stress Inducing Cardiovascular Disease in Cancer Patients

Reactive oxygen species (ROS) are molecules involved in signal transduction pathways with both beneficial and detrimental effects on human cells. ROS are generated by many cellular processes including mitochondrial respiration, metabolism and enzymatic activities. In physiological conditions, ROS levels are well-balanced by antioxidative detoxification systems. In contrast, in pathological conditions such as cardiovascular, neurological and cancer diseases, ROS production exceeds the antioxidative detoxification capacity of cells, leading to cellular damages and death. In this review, we will first describe the biology and mechanisms of ROS mediated oxidative stress in cardiovascular disease. Second, we will review the role of oxidative stress mediated by oncological treatments in inducing cardiovascular disease. Lastly, we will discuss the strategies that potentially counteract the oxidative stress in order to fight the onset and progression of cardiovascular disease, including that induced by oncological treatments.

5-Fluorouracil disrupts ovarian preantral follicles in young C57BL6J mice

PURPOSE

5-Fluorouracil (5-FU), an anti-cancer drug, has been used for hepatoblastoma (HB) chemotherapy in children, who may have impaired  ovarian follicle pool reserve with lasting effects to reproduction. Therefore, this study aimed to investigate 5-FU effects on survival, growth, and morphology of ovarian preantral follicles from C57BL6J young mice.

METHODS

Experiments were carried-out both in vivo and in vitro. Mice were treated with 5-FU injection (450 mg/kg i.p) or saline and sacrificed 3 days after to obtain ovaries for histology and molecular biology. Ovaries for in vitro studies were obtained from unchallenged mice and cultured under basic culture medium (BCM) or BCM plus 5-FU (9.2, 46.1, 92.2 mM). Preantral follicles were classified according to developmental stages, and as normal or degenerated. To assess cell viability, caspase-3 immunostaining was performed. Transcriptional levels for apoptosis (Bax, Bcl2, p53, Bax/Bcl2) and Wnt pathway genes (Wnt2 and Wnt4) were also analyzed. Ultrastructural analyses were carried-out on non-cultured ovaries. In addition, β-catenin immunofluorescence was assessed in mouse ovaries.

RESULTS

The percentage of all-types normal follicles was significantly lower after 5-FU challenge. A total loss of secondary normal follicles was found in the 5-FU group. The highest 5-FU concentrations reduced the percentage of cultured normal primordial follicles. Large vacuoles were seen in granulosa cells and ooplasm of preantral follicles by electron microscopy. A significantly higher gene expression for Bax and Bax/Bcl2 ratio was seen after 5-FU treatment. A marked reduction in β-catenin immunolabeling was seen in 5-FU-challenged preantral follicles. In the in vitro experiments, apoptotic and Wnt gene transcriptions were significantly altered.

CONCLUSION

Altogether, our findings suggest that 5-FU can deleteriously affect the ovarian follicle reserve by reducing preantral follicles survival.

Emerging role of NRF2 in ROS-mediated tumor chemoresistance

Chemoresistance is a central cause for the tumor management failure. Cancer cells disrupt the redox homeostasis through reactive oxygen species (ROS) regulatory mechanisms, leading to tumor progression and chemoresistance. The transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) is a master regulator of neutralizing cellular ROS and restoring redox balance. Understanding the role of NRF2 in ROS-mediated chemoresistance can be helpful in the development of chemotherapy strategies with better efficiency. In this review, we sum up the roles of ROS in the development of chemoresistance to classical chemotherapy agents including cisplatin, 5-fluorouracil, gemcitabine, oxaliplatin, paclitaxel, and doxorubicin, and how to overcome ROS-mediated tumor chemoresistance by targeting NRF2. Finally, we propose that targeting NRF2 might be a promising strategy to resist ROS-driven chemoresistance and acquire better efficacy in cancer treatment.

Targeted delivery of 5-fluorouracil-1-acetic acid (5-FA) to cancer cells overexpressing epithelial growth factor receptor (EGFR) using virus-like nanoparticles

Chemotherapy is widely used in cancer treatments. However, non-specific distribution of chemotherapeutic agents to healthy tissues and normal cells in the human body always leads to adverse side effects and disappointing therapeutic outcomes. Therefore, the main aim of this study was to develop a targeted drug delivery system based on the hepatitis B virus-like nanoparticle (VLNP) for specific delivery of 5-fluorouracil-1-acetic acid (5-FA) to cancer cells expressing epithelial growth factor receptor (EGFR). 5-FA was synthesized from 5-fluorouracil (5-FU), and it was found to be less toxic than the latter in cancer cells expressing different levels of EGFR. The cytotoxicity of 5-FA increased significantly after being conjugated on the VLNP. A cell penetrating peptide (CPP) of EGFR was displayed on the VLNP via the nanoglue concept, for targeted delivery of 5-FA to A431, HT29 and HeLa cells. The results showed that the VLNP displaying the CPP and harboring 5-FA internalized the cancer cells and killed them in an EGFR-dependent manner. This study demonstrated that the VLNP can be used to deliver chemically modified 5-FU derivatives to cancer cells overexpressing EGFR, expanding the applications of the VLNP in targeted delivery of chemotherapeutic agents to cancer cells overexpressing this transmembrane receptor.

Dietary Glycine Prevents FOLFOX Chemotherapy-Induced Heart Injury: A Colorectal Cancer Liver Metastasis Treatment Model in Rats

Introduction: FOLFOX chemotherapy (CTx) is used for the treatment of colorectal liver metastasis (CRLM). Side effects include rare cardiotoxicity, which may limit the application of FOLFOX. Currently, there is no effective strategy to prevent FOLFOX-induced cardiotoxicity. Glycine has been shown to protect livers from CTx-induced injury and oxidative stress, and it reduces platelet aggregation and improves microperfusion. This study tested the hypothesis of glycine being cardioprotective in a rat model of FOLFOX in combination with CRLM. Materials and Methods: The effect of glycine was tested in vitro on human cardiac myocytes (HCMs). To test glycine in vivo Wag/Rij rats with induced CRLM were treated with FOLFOX ±5% dietary glycine. Left ventricle ejection fraction (LVEF), myocardial fibrosis, and apoptosis, also heart fatty acid binding protein (h-FABP) and brain natriuretic peptide levels were monitored. PCR analysis for Collagen type I, II, and brain natriuretic peptide (BNP) in the heart muscle was performed. Results: In vitro glycine had no effect on HCM cell viability. Treatment with FOLFOX resulted in a significant increase of h-FABP levels, increased myocardial fibrosis, and apoptosis as well as increased expression of type I Collagen. Furthermore, FOLFOX caused a decrease of LVEF by 10% (p = 0.028). Dietary glycine prevented FOLFOX-induced myocardial injury by preserving the LVEF and reducing the levels of fibrosis (p = 0.012) and apoptosis (p = 0.015) in vivo. Conclusions: Data presented here demonstrate for the first time that dietary glycine protects the heart against FOLFOX-induced injury during treatment for CRLM.

Novel Therapeutic Application of Self-Assembly Peptides Targeting the Mitochondria in In Vitro and In Vivo Experimental Models of Gastric Cancer

Here, we provide the possibility of a novel chemotherapeutic agent against gastric cancer cells, comprising the combination of 5-fluorouracil (5-FU) and a mitochondria-targeting self-assembly peptide, which is a phenylalanine dipeptide with triphenyl phosphonium (Mito-FF). The anticancer effects and mechanisms of 5-FU and Mito-FF, individually or in combination, were compared through both in vitro and in vivo models of gastric cancer. Our experiments consistently demonstrated that the 5-FU and Mito-FF combination therapy was superior to monotherapy with either, as manifested by both higher reduction of proliferation as well as an induction of apoptotic cell death. Interestingly, we found that combining 5-FU with Mito-FF leads to a significant increase of reactive oxygen species (ROS) and reduction of antioxidant enzymes in gastric cancer cells. Moreover, the inhibition of ROS abrogated the pro-apoptotic effects of combination therapy, suggesting that enhanced oxidative stress could be the principal mechanism of the action of combination therapy. We conclude that the combination of 5-FU and Mito-FF exerts potent antineoplastic activity against gastric cancer cells, primarily by promoting ROS generation and suppressing the activities of antioxidant enzymes.

Molecular Mechanisms of Cardiomyocyte Death in Drug-Induced Cardiotoxicity

Homeostatic regulation of cardiomyocytes plays a crucial role in maintaining the normal physiological activity of cardiac tissue. Severe cardiotoxicity results in cardiac diseases including but not limited to arrhythmia, myocardial infarction and myocardial hypertrophy. Drug-induced cardiotoxicity limits or forbids further use of the implicated drugs. Such drugs that are currently available in the clinic include anti-tumor drugs (doxorubicin, cisplatin, trastuzumab, etc.), antidiabetic drugs (rosiglitazone and pioglitazone), and an antiviral drug (zidovudine). This review focused on cardiomyocyte death forms and related mechanisms underlying clinical drug-induced cardiotoxicity, including apoptosis, autophagy, necrosis, necroptosis, pryoptosis, and ferroptosis. The key proteins involved in cardiomyocyte death signaling were discussed and evaluated, aiming to provide a theoretical basis and target for the prevention and treatment of drug-induced cardiotoxicity in the clinical practice.

High Density Lipoprotein and Its Precursor Protein Apolipoprotein A1 as Potential Therapeutics to Prevent Anthracycline Associated Cardiotoxicity

Cardiovascular disease and cancer are the leading causes of death in developed societies. Despite their effectiveness, many cancer therapies exhibit deleterious cardiovascular side effects such as cardiotoxicity and heart failure. The cardiotoxic effects of anthracyclines such as doxorubicin are the most well-characterized of cardiotoxic anti-cancer therapies. While other anti-neoplastic drugs also induce cardiotoxicity, often leading to heart failure, they are beyond the scope of this review. This review first summarizes the mechanisms of doxorubicin-induced cardiotoxicity. It then reviews emerging preclinical evidence that high density lipoprotein and its precursor protein apolipoprotein A1, which are known for their protective effects against ischemic cardiovascular disease, may also protect against doxorubicin-induced cardiotoxicity both directly and indirectly, when used therapeutically.

Combined in silico and 19F NMR analysis of 5-fluorouracil metabolism in yeast at low ATP conditions

The cytotoxic effect of 5-fluorouracil (5-FU) on yeast cells is thought to be mainly via a misincorporation of fluoropyrimidines into both RNA and DNA, not only DNA damage via inhibition of thymidylate synthase (TYMS) by fluorodeoxyuridine monophosphate (FdUMP). However, some studies on Saccharomyces cerevisiae show a drastic decrease in ATP concentration under oxidative stress, together with a decrease in concentration of other tri- and diphosphates. This raises a question if hydrolysis of 5-fluoro-2-deoxyuridine diphosphate (FdUDP) under oxidative stress could not lead to the presence of FdUMP and the activation of so-called 'thymine-less death' route. We attempted to answer this question with in silico modeling of 5-FU metabolic pathways, based on new experimental results, where the stages of intracellular metabolism of 5-FU in Saccharomyces cerevisiae were tracked by a combination of 19F and 31P NMR spectroscopic study. We have identified 5-FU, its nucleosides and nucleotides, and subsequent di- and/or triphosphates. Additionally, another wide 19F signal, assigned to fluorinated unstructured short RNA, has been also identified in the spectra. The concentration of individual metabolites was found to vary substantially within hours, however, the initial steady-state was preserved only for an hour, until the ATP concentration dropped by a half, which was monitored independently via 31P NMR spectra. After that, the catabolic process leading from triphosphates through monophosphates and nucleosides back to 5-FU was observed. These results imply careful design and interpretation of studies in 5-FU metabolism in yeast.

The expression of p-p62 and nuclear Nrf2 in esophageal squamous cell carcinoma and association with radioresistance

Background

The roles of p62‐Keap1‐Nrf2 pathway in the radioresistance of esophageal squamous cell carcinoma (ESCC) have not yet been revealed. This study aimed to clarify the expression and correlation of p‐p62 and nuclear Nrf2 and their association with radioresistance in ESCC.

Methods

This study included 164 cases of inoperable locally advanced ESCC. All patients received concurrent chemoradiotherapy (CCRT). Immunohistochemical staining was used to detect the expression of p‐p62 and nuclear Nrf2. The results were analyzed independently by two pathologists.

Results

There was no significant relationship between p‐p62 or nuclear Nrf2 and patients' clinical characteristics. Compared to patients with low expression of p‐p62, patients with high expression of p‐p62 showed lower objective response rate (ORR). Similarly, patients with high expression of nuclear Nrf2 exhibited lower ORR compared to those with low expression of nuclear Nrf2. The expression of p‐p62 was positively correlated with that of nuclear Nrf2. Moreover, the correlation coefficient between them was higher among patients showing no response to CCRT. Univariate analysis revealed that higher expression of p‐p62 or nuclear Nrf2 was significantly associated with poorer PFS and OS. Multivariate analysis indicated that the expression of nuclear Nrf2 and treatment response were independent prognostic factors for PFS. Sex, treatment response, expression of p‐p62 and nuclear Nrf2 were independent prognostic factors for OS.

Conclusion

Higher expression of p‐p62 and nuclear Nrf2 are associated with lower ORR as well as poorer prognosis, which indicates that p62‐Keap1‐Nrf2 pathway might play an essential role in the radioresistance of ESCC.

Key points

The expression of p‐p62 and nuclear Nrf2 in ESCC show a significant relationship with patients' responses to CCRT and influence the prognosis of ESCC.

p62‐Keap1‐Nrf2 pathway might be a new target for radiosensitization in ESCC.

Is there a role for remote ischemic conditioning in preventing 5-fluorouracil-induced coronary vasospasm?

Cardiac ischemia associated with chemotherapy has been linked to several anti-neoplastic agents and is multifactorial in etiology. Coronary artery vasospasm is one of the most commonly reported effects of cancer therapy that can lead to myocardial ischemia or infarction. The chemotherapy agent 5-fluorouracil (5-FU) or its oral pro-drug capecitabine can result in coronary vascular endothelial dysfunction causing coronary artery spasm, and possibly coronary thrombosis. These drugs have also been shown to be associated with myocardial infarction, malignant ventricular arrhythmias, heart failure, cardiogenic shock, and sudden death. The proposed mechanisms underlying cardiotoxicity induced by 5-FU are vascular endothelial damage followed by thrombus formation, ischemia secondary to coronary artery vasospasm, direct toxicity on myocardium, and thrombogenicity. There remains a pressing need to discover novel and effective therapies that can prevent or ameliorate 5-FU associated cardiotoxicity. To this point, promising overlap has been observed between proposed remote ischemic conditioning (RIC) cardioprotective mechanisms and 5FU-associated cardiotoxic cellular pathways. RIC, in which transient episodes of limb ischemia and reperfusion (induced by inflations and deflations of a pneumatic cuff placed on the upper arm or thigh), confer both cardioprotective and vasculoprotective effects, and may therefore prevent 5-FU coronary artery spasm/cardiotoxicity. In this review, we will be discussing the following potentially therapeutic aspects of RIC in ameliorating 5-FU associated cardiotoxicity: sequential phases of 5-FU cardiotoxicity as possible targets for dual windows of cardioprotection characteristic of RIC; protective effects of RIC on endothelial function and microvasculature in relation to 5-FU induced endothelial dysfunction/microvascular dysfunction; reduction in platelet activation by RIC in the context of 5-FU induced thrombogenicity; and the utility of improvement in mitochondrial function conferred by RIC in 5-FU induced cellular toxicity secondary to mitochondrial dysfunction.

Guar gum modified upconversion nanocomposites for colorectal cancer treatment through enzyme-responsive drug release and NIR-triggered photodynamic therapy

Multimodal therapeutic approach towards colorectal cancer (CRC) holds great promise. There is, however, no convincing strategy reported to date that employs a multimodal strategy in CRC treatment. The present study reports an intense green-emitting core-shell photoluminescent upconversion (CSGU) nanocrystal engineered to synergistically perform photodynamic and enzyme-triggered delivery of the chemotherapeutic agent for an enhanced therapeutic outcome on HT-29 colon carcinoma cells in vitro. The photodynamic activity is achieved by the energy transfer between CSGU and the chemically conjugated Rose Bengal (RB) molecules that are further protected by a mesoporous silica (MS) layer. The chemical assay demonstrates a remarkable FRET mediated generation of ¹O₂ under NIR (980 nm) excitation. The outermost MS layer of the nanoplatform is utilized for the loading of the 5FU anticancer drug, which is further capped with a guar gum (GG) polysaccharide polymer. The release of the 5FU is specifically triggered by the degradation of the GG cap by specific enzymes secreted from colonic microflora, which otherwise showed 'zero-release behavior' in the absence of any enzymatic trigger in various simulated gastro-intestinal (GI) conditions. Furthermore, the enhanced therapeutic efficacy of the nanoplatform (CSGUR-MSGG/5FU) was evaluated through in vitro studies using HT-29 CRC cell lines by various biochemical and microscopic assays by the simultaneous triggering effect of colonic enzyme and 980 nm laser excitation. In addition, the strong visible emission from the nanoplatform has been utilized for NIR-induced cellular bioimaging.

Co-treatment With BGP-15 Exacerbates 5-Fluorouracil-Induced Gastrointestinal Dysfunction

Gastrointestinal (GI) side-effects of chemotherapy present a constant impediment to efficient and tolerable treatment of cancer. GI symptoms often lead to dose reduction, delays and cessation of treatment. Chemotherapy-induced nausea, bloating, vomiting, constipation, and/or diarrhea can persist up to 10 years post-treatment. We have previously reported that long-term 5-fluorouracil (5-FU) administration results in enteric neuronal loss, acute inflammation and intestinal dysfunction. In this study, we investigated whether the cytoprotectant, BGP-15, has a neuroprotective effect during 5-FU treatment. Balb/c mice received tri-weekly intraperitoneal 5-FU (23 mg/kg/d) administration with and without BGP-15 (15 mg/kg/d) for up to 14 days. GI transit was analyzed via in vivo serial X-ray imaging prior to and following 3, 7, and 14 days of treatment. On day 14, colons were collected for assessment of ex vivo colonic motility, neuronal mitochondrial superoxide, and cytochrome c levels as well as immunohistochemical analysis of myenteric neurons. BGP-15 did not inhibit 5-FU-induced neuronal loss, but significantly increased the number and proportion of choline acetyltransferase (ChAT)-immunoreactive (IR) and neuronal nitric oxide synthase (nNOS)-IR neurons in the myenteric plexus. BGP-15 co-administration significantly increased mitochondrial superoxide production, mitochondrial depolarization and cytochrome c release in myenteric plexus and exacerbated 5-FU-induced colonic inflammation. BGP-15 exacerbated 5-FU-induced colonic dysmotility by reducing the number and proportion of colonic migrating motor complexes and increasing the number and proportion of fragmented contractions and increased fecal water content indicative of diarrhea. Taken together, BGP-15 co-treatment aggravates 5-FU-induced GI side-effects, in contrast with our previous findings that BGP-15 alleviates GI side-effects of oxaliplatin.

The Main Metabolites of Fluorouracil + Adriamycin + Cyclophosphamide (FAC) Are Not Major Contributors to FAC Toxicity in H9c2 Cardiac Differentiated Cells

In the clinical practice, the combination of 5-fluorouracil (5-FU) + Adriamycin (also known as doxorubicin, DOX) + cyclophosphamide (CYA) (known as FAC) is used to treat breast cancer. The FAC therapy, however, carries some serious risks, namely potential cardiotoxic effects, although the mechanisms are still unclear. In the present study, the role of the main metabolites regarding FAC-induced cardiotoxicity was assessed at clinical relevant concentrations. Seven-day differentiated H9c2 cells were exposed for 48 h to the main metabolites of FAC, namely the metabolite of 5-FU, α-fluoro-β-alanine (FBAL, 50 or 100 μM), of DOX, doxorubicinol (DOXOL, 0.2 or 1 μM), and of CYA, acrolein (ACRO, 1 or 10 μM), as well as to their combination. The parent drugs (5-FU 50 μM, DOX 1 μM, and CYA 50 μM) were also tested isolated or in combination with the metabolites. Putative cytotoxicity was evaluated through phase contrast microscopy, Hoechst staining, membrane mitochondrial potential, and by two cytotoxicity assays: the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and the neutral red (NR) lysosomal incorporation. The metabolite DOXOL was more toxic than FBAL and ACRO in the MTT and NR assays. When in combination, neither FBAL nor ACRO increased DOXOL-induced cytotoxicity. No nuclear condensation was observed for any of the tested combinations; however, a significant mitochondrial potential depolarization after FBAL 100 μM + DOXOL 1 μM + ACRO 10 μM or FBAL 100 μM + DOXOL 1 μM exposure was seen at 48 h. When tested alone DOX 1 μM was more cytotoxic than all the parent drugs and metabolites in both the cytotoxicity assays performed. These results demonstrated that DOXOL was the most toxic of all the metabolites tested; nonetheless, the metabolites do not seem to be the major contributors to FAC-induced cardiotoxicity in this cardiac model.

CD44 standard isoform is involved in maintenance of cancer stem cells of a hepatocellular carcinoma cell line

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer death worldwide. Cancer stem cells (CSCs) have attracted attention as a novel therapeutic target for cancer because they play important roles in the development and aggravation of cancer. CD44 is expressed as a standard isoform (CD44s) and several variant isoforms. CD44v is a major isoform expressed on CSCs of a variety of tumors and has been extensively studied. However, HCC tissues dominantly express CD44s, whose function in CSCs remains unclear. In the present study, we investigated the roles of CD44s in CSCs of HCC. Knock‐out of the CD44 gene in HuH7 HCC cells on which only CD44s is expressed resulted in decreased spheroid formation and increased drug sensitivity. The expression of CSC marker genes, including CD133 and EpCAM, was significantly downregulated in the spheroids of CD44‐deficient cells compared with those in the spheroids of HuH7 cells. In addition, CD44 deficiency impaired antioxidant capacity, concomitant with downregulation of glutathione peroxidase 1 (GPX1) and thioredoxin. Because GPX1 uses the reduced form of glutathione (GSH) to regenerate oxidized cellular components, GSH levels were significantly increased in the CD44‐deficient cells. We also found that NOTCH3 and its target genes were downregulated in the spheroids of CD44‐deficient cells. NOTCH3 expression in HCC tissues was significantly increased compared with that in adjacent nontumor liver tissues and was correlated with CD44 expression. These results suggest that CD44s is involved in maintenance of CSCs in a HCC cell line, possibly through the NOTCH3 signaling pathway.

Doxorubicin Is Key for the Cardiotoxicity of FAC (5-Fluorouracil + Adriamycin + Cyclophosphamide) Combination in Differentiated H9c2 Cells

Currently, a common therapeutic approach in cancer treatment encompasses a drug combination to attain an overall better efficacy. Unfortunately, it leads to a higher incidence of severe side effects, namely cardiotoxicity. This work aimed to assess the cytotoxicity of doxorubicin (DOX, also known as Adriamycin), 5-fluorouracil (5-FU), cyclophosphamide (CYA), and their combination (5-Fluorouracil + Adriamycin + Cyclophosphamide, FAC) in H9c2 cardiac cells, for a better understanding of the contribution of each drug to FAC-induced cardiotoxicity. Differentiated H9c2 cells were exposed to pharmacological relevant concentrations of DOX (0.13–5 μM), 5-FU (0.13–5 μM), CYA (0.13–5 μM) for 24 or 48 h. Cells were also exposed to FAC mixtures (0.2, 1 or 5 μM of each drug and 50 μM 5-FU + 1 μM DOX + 50 μM CYA). DOX was the most cytotoxic drug, followed by 5-FU and lastly CYA in both cytotoxicity assays (reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and neutral red (NR) uptake). Concerning the equimolar combination with 1 or 5 μM, FAC caused similar cytotoxicity to DOX alone. Even in the presence of higher concentrations of 5-FU and CYA (50 μM 5-FU + 1 μM DOX + 50 μM CYA), 1 μM DOX was still a determinant for the cardiotoxicity observed in the cytotoxicity assays, phase contrast morphological evaluation, and mitochondrial potential depolarization evaluation. To the best of our knowledge, this was the first in vitro work with this combination regimen, DOX being the most toxic drug and key to the toxicity of FAC.

The cardioprotective effect of dexrazoxane (Cardioxane) is consistent with sequestration of poly(ADP-ribose) by self-assembly and not depletion of topoisomerase 2B

Following systematic scrutiny of the evidence in support of the hypothesis that the cardioprotective mechanism of action of dexrazoxane is mediated by a 'depletion' or 'downregulation' of Top2β protein levels in heart tissue, the author concludes that this hypothesis is untenable. In seeking to understand how dexrazoxane protects the heart, the outcomes of a customised association rule learning algorithm incorporating the use of antecedent surrogate variables (CEME, 2017 McCormack Pharma) reveal a previously unknown relationship between dexrazoxane and poly(ADP-ribose) (PAR) polymer. The author shows how this previously unknown relationship explains both acute and long-term cardioprotection in patients receiving anthracyclines. In addition, as a direct inhibitor of PAR dexrazoxane has access to the epigenome and this offers a new insight into protection by dexrazoxane against doxorubicin-induced late-onset damage [McCormack K, manuscript in preparation]. Notably, through this review article, the author illustrates the practical application of probing natural language text using an association rule learning algorithm for the discovery of new and interesting associations that, otherwise, would remain lost. Historically, the use of CEME enabled the first report of the capacity of a small molecule to catalyse the hybrid self-assembly of a nucleic acid biopolymer via canonical and non-canonical, non-covalent interactions analogous to Watson Crick and Hoogsteen base pairing, respectively.

Indole Alkaloid Derivative B, a Novel Bifunctional Agent That Mitigates 5-Fluorouracil-Induced Cardiotoxicity

Clinically approved therapeutics that mitigate chemotherapy-induced cardiotoxicity, a serious adverse effect of chemotherapy, are lacking. The aim of this study was to determine the putative protective capacity of a novel indole alkaloid derivative B (IADB) against 5-fluorouracil (5-FU)-induced cardiotoxicity. To assess the free-radical scavenging activities of IADB, the acetylcholine-induced relaxation assay in rat thoracic aorta was used. Further, IADB was tested in normal and cancer cell lines with assays gauging autophagy induction. We further examined whether IADB could attenuate cardiotoxicity in 5-FU-treated male ICR mice. We found that IADB could serve as a novel bifunctional agent (displaying both antioxidant and autophagy-modulating activities). Further, we demonstrated that IADB induced production of cytosolic autophagy-associated structures in both cancer and normal cell lines. We observed that IADB cytotoxicity was much lower in normal versus cancer cell lines, suggesting an enhanced potency toward cancer cells. The cardiotoxicity induced by 5-FU was significantly relieved in animals pretreated with IADB. Taken together, IADB treatment, in combination with chemotherapy, may lead to reduced cardiotoxicity, as well as the reduction of anticancer drug dosages that may further improve chemotherapeutic efficacy with decreased off-target effects. Our data suggest that the use of IADB may be therapeutically beneficial in minimizing cardiotoxicity associated with high-dose chemotherapy. On the basis of the redox status difference between normal and tumor cells, IADB selectively induces autophagic cell death, mediated by reactive oxygen species overproduction, in cancer cells. This novel mechanism could reveal novel therapeutic targets in chemotherapy-induced cardiotoxicity.

Mitochondrial Dynamics in Rat Heart Induced by 5-Fluorouracil

BACKGROUND Patients treated with 5-FU can develop rare but potentially severe cardiac effects, including cardiomyopathy, angina pectoris, ventricular tachycardia, heart failure, acute myocardial infarction, and cardiogenic shock. The specific pathologies and mechanisms are not fully understood. Research found that mitochondrial dynamics are widely detected in many angiocardiopathies. Therefore, in the present study we studied the mitochondrial damage and explored the role of mitochondrial fusion/fission proteins on myocardium of rats treated with 5-fluorouracil (5-FU). MATERIAL AND METHODS Thirty male SD rats were randomly divided into 3 groups with 10 rats in each group: (1) control group, (2) low 5-FU group (25 mg/kg), (3) high 5-FU group (50 mg/kg). The animals received intraperitoneal injection for 5 consecutive days. We assessed alterations in mitochondrial morphology, ATP content, mitochondrial membrane potential, and mitochondria fusion/fission proteins expression in hearts of rats receiving intraperitoneal injection with different doses of 5-FU. RESULTS 5-FU intraperitoneal injection induced ultra-structural damage in hearts, such as mitochondrial swelling, cristae disorder, and vacuolization. These changes were accompanied by decreases of mitochondrial membrane potential. The low dose of 5-FU led to a slight increase in ATP content. However, the high 5-FU dose caused a more significant reduction compared with the control group. Furthermore, 5-FU intraperitoneal injection significantly increased specific mitochondrial fission proteins (Drp1 and Fis1) and decreased mitochondrial fusion proteins (Opa1, Mfn1, and Mfn2) in rat hearts. However, no changes in cardiac structure and function were detected by echocardiogram. The high dose caused more damage to mitochondrial function than the low dose. CONCLUSIONS Mitochondrial damage is a potentially important mechanism and early indicator for 5-FU-induced cardiovascular disease.