l-carnosine induces apoptosis/cell cycle arrest via suppression of NF-κB/STAT1 pathway in HCT116 colorectal cancer cells

Karnozin EXTRA® causes changes in mitochondrial bioenergetics response in MCF-7 and MRC-5 cell lines

Numerous studies reported about potential effects of L-carnosine in regulation of tumor growth and metabolism. We evaluated the effects of different concentrations of L-carnosine from Karnozin EXTRA® supplement on mitochondrial respiratory chain complexes of human embryo lung fibroblasts (MRC-5) and human breast cancer cells (MCF-7), with different energy pathways. Also, we analyzed the proliferation index and expression of various markers of oxidative stress. Treatment with Karnozin EXTRA® (concentration of L-carnosine were 2, 5 and 10 mM) for 24 hours gradually decreased the number of cells and changed their morphological features. In both cell lines, a dose-dependent reduction of cell viability was recorded compared to the control group. Also, experimental groups showed a concentration-dependent decrease in fluorescence intensity of SOD2 expressions in MCF-7, while in MRC-5 we noticed higher fluorescence intensity in Carnosine 2 mM group. Treated cells, in both cell lines, showed different intensity of iNOS cytoplasmic immunopositivity in a concentration-dependent manner. In all experimental groups, we noticed an increased expression of marker of oxidative stress-cytochrome P450 2E1 (CYP2E1). The effects of Karnozin EXTRA® capsule on mitochondrial respiration, assessed with the Clark-type electrode, were manifested as a reduction of: basal cell respiration, maximum capacity of electron transport chain and mitochondrial ATP-linked respiration. Also, significant decrease in the activity of complex I (NADH-ubiquinone oxidoreductase), complex II (succinate dehydrogenase) and complex IV (cytochrome c oxidase) was observed in both cell lines. Bearing in mind that Karnozin EXTRA® is a potential regulator of energy metabolism of MCF-7 and MRC-5, these results provide a good basis for further preclinical and clinical research.

Curcumin mitigates polycystic ovary syndrome in mice by suppressing TLR4/MyD88/NF-κB signaling pathway activation and reducing intestinal mucosal permeability

Polycystic ovary syndrome (PCOS) is an endocrine-metabolic disorder closely associated with chronic inflammation. Curcumin, a polyphenolic lipophilic compound, has been shown to improve the intestinal mucosal barrier and reduce low-grade systemic inflammation. This study aimed to assess the effects of curcumin on attenuation of PCOS in a mouse model and to explore the underlying mechanisms involved. C57BL/6J mice were divided into 4 groups (n = 15 per group): CON: control group, CON/CUR: CON with curcumin group, MOD: model group, MOD/CUR: MOD with curcumin group. The MOD and MOD/CUR groups were injected with dehydroepiandrosterone (DHEA) (6 mg/100 g BW) dissolved in soybean oil to induce a PCOS-like state. After curcumin intervention (200 mg/kg) for 45 days, the mice were euthanized for analysis of various physiological and biochemical parameters. In MOD/CUR group, significant decreases in body weight (BW) (p = 0.0254), testosterone (T) levels (p = 0.0052), luteinizing hormone (LH) levels (p = 0.0438), and the LH/follicle-stimulating hormone (FSH) (p = 0.0271) levels were observed, while estradiol (E2) (p = 0.0415) level and insulin sensitivity (p = 0.0441) were increased. Histological examination (HE) staining of ovarian and colon tissues showed that curcumin ameliorated both PCOS-associated morphological changes and colon tissue pathology. Western blot and immunohistochemistry analyses of colon tissues revealed increased levels of tight junction proteins, ZO-1 (Western blot, p = 0.0360; immunohistochemistry, p = 0.0273) and occluding (Western blot, p = 0.0189; immunohistochemistry, p = 0.0224) in the MOD/CUR group. Additionally, inflammatory indicators from plasma and ovary, including IL-17 A (plasma, p = 0.0120; ovary, p = 0.0414), IL-6 (plasma, p = 0.0344; ovary, p = 0.0379), TNF-α (plasma, p = 0.0078; ovary, p = 0.0488), and lipopolysaccharides (LPS) (plasma, p = 0.0144), were decreased, while IL-10 (plasma, p = 0.0270; ovary, p = 0.0267) was increased in MOD/CUR group. The levels of NF-κB p65 (p = 0.0229), TLR-4 (p = 0.0462) and MyD88 (p = 0.0152) in ovarian tissues were significantly increased in MOD/CUR group. Our results revealed that curcumin alleviates PCOS by inhibiting TLR4/MyD88/NF-κB signaling pathway activation and reducing intestinal mucosal permeability. These findings suggest that curcumin may provide a potential clinical approach for managing PCOS.

Targeted colorectal cancer treatment: In vitro anti-cancer effects of carnosine nanoparticles supported by agar and magnetic iron oxide

The usage of peptides in the colorectal cancer (CRC) treatment promises to be a new anti-cancer therapy with improved treatment efficacy. Carnosine, a natural dipeptide molecule, has been demonstrated to be a potential anti-cancer drug. Nonetheless, it shows an exhibition of high-water solubility and is quickly degraded by carnosinase. Meanwhile, agar and magnetic iron oxide are the most used materials for drug delivery due to some of their advantages such as the low cost and the larger biocompatibility feature. The purpose of this study was to investigate the anti-cancer ability of agar-encapsulated carnosine nanoparticles (AgCa-NPs) and agar-encapsulated carnosine nanoparticles-coated magnetic iron oxide nanoparticles (AgCaN-MNPs) in human CRC cells, HCT-116. We evaluated the effects of AgCa-NPs and AgCaN-MNPs with a variety of concentrations (0, 5, 10, 15, 30, 40, or 50 mM) on HCT-116 cells after 72 h and 96 h by using MTT assay and observation cell morphology. We then analyzed the cell cycle progression and assessed the expression changes of genes related to apoptosis, autophagy, necroptosis, and angiogenesis after treatment for 96 h. The results showed that AgCa-NPs and AgCaN-MNPs in vitro study decreased HCT-116 cells viability. This effect was attributed to arrest of cell cycle, induction of programmed cell death, and suppression of angiogenesis by AgCa-NPs and AgCaN-MNPs. These findings revealed the antitumor efficacy of AgCa-NPs or AgCaN-MNPs for CRC treatment.

Beef peptides mitigate skeletal muscle atrophy in C2C12 myotubes through protein degradation, protein synthesis, and the oxidative stress pathway

This study aimed to investigate the potential of beef peptides (BPs) in mitigating muscle atrophy induced by dexamethasone (DEX) with underlying three mechanisms in vitro (protein degradation, protein synthesis, and the oxidative stress pathway). Finally, the anti-atrophic effect of BPs was enhanced through purification and isolation. BPs were generated using beef loin hydrolyzed with alcalase/ProteAX/trypsin, each at a concentration of 0.67%, followed by ultrafiltration through a 3 kDa cut-off. BPs (10-100 μg mL-1) dose-dependently counteracted the DEX-induced reductions in myotube diameters, differentiation, fusion, and maturation indices (p < 0.05). Additionally, BPs significantly reduced FoxO1 protein dephosphorylation, thereby suppressing muscle-specific E3 ubiquitin ligases such as muscle RING-finger containing protein-1 and muscle atrophy F-box protein in C2C12 myotubes at concentrations exceeding 25 μg mL-1 (p < 0.05). BPs also enhanced the phosphorylation of protein synthesis markers, including mTOR, 4E-BP1, and p70S6K1, in a dose-dependent manner (p < 0.05) and increased the mRNA expression of antioxidant enzymes. Fractionated peptides derived from BPs, through size exclusion and polarity-based fractionation, also demonstrated enhanced anti-atrophic effects compared to BPs. These peptides downregulated the mRNA expression of primary muscle atrophy markers while upregulated that of antioxidant enzymes. Specifically, peptides GAGAAGAPAGGA (MW 924.5) and AFRSSTKK (MW 826.4) were identified from fractionated peptides of BPs. These findings suggest that BPs, specifically the peptide fractions GAGAAGAPAGGA and AFRSSTKK, could be a potential strategy to mitigate glucocorticoid-induced skeletal muscle atrophy by reducing the E3 ubiquitin ligase activity.

The Anti-Cancer Activity of the Naturally Occurring Dipeptide Carnosine: Potential for Breast Cancer

Carnosine is an endogenous dipeptide composed of β-alanine and L-histidine, possessing a multimodal pharmacodynamic profile that includes anti-inflammatory and anti-oxidant activities. Carnosine has also shown its ability to modulate cell proliferation, cell cycle arrest, apoptosis, and even glycolytic energy metabolism, all processes playing a key role in the context of cancer. Cancer is one of the most dreaded diseases of the 20th and 21st centuries. Among the different types of cancer, breast cancer represents the most common non-skin cancer among women, accounting for an estimated 15% of all cancer-related deaths in women. The main aim of the present review was to provide an overview of studies on the anti-cancer activity of carnosine, and in particular its activity against breast cancer. We also highlighted the possible advantages and limitations involved in the use of this dipeptide. The first part of the review entailed a brief description of carnosine's biological activities and the pathophysiology of cancer, with a focus on breast cancer. The second part of the review described the anti-tumoral activity of carnosine, for which numerous studies have been carried out, especially at the preclinical level, showing promising results. However, only a few studies have investigated the therapeutic potential of this dipeptide for breast cancer prevention or treatment. In this context, carnosine has shown to be able to decrease the size of cancer cells and their viability. It also reduces the levels of vascular endothelial growth factor (VEGF), cyclin D1, NAD+, and ATP, as well as cytochrome c oxidase activity in vitro. When tested in mice with induced breast cancer, carnosine proved to be non-toxic to healthy cells and exhibited chemopreventive activity by reducing tumor growth. Some evidence has also been reported at the clinical level. A randomized phase III prospective placebo-controlled trial showed the ability of Zn-carnosine to prevent dysphagia in breast cancer patients undergoing adjuvant radiotherapy. Despite this evidence, more preclinical and clinical studies are needed to better understand carnosine's anti-tumoral activity, especially in the context of breast cancer.

L-carnosine Attenuates Bleomycin-Induced Oxidative Stress via NFκB Pathway in the Pathogenesis of Pulmonary Fibrosis

Idiopathic Pulmonary fibrosis (IPF), a chronic interstitial lung disease, has pulmonary manifestations clinically characterized by collagen deposition, epithelial cell injury, and a decline in lung function. L-carnosine, a dipeptide consisting of β-alanine and L-histidine, has demonstrated a therapeutic effect on various diseases because of its pivotal function. Despite the effect of L-carnosine in experimental IPF mice, its anti-oxidative effect and associated intercellular pathway, particularly alveolar epithelial cells, remain unknown. Therefore, we demonstrated the anti-fibrotic and anti-inflammatory effects of L-carnosine via Reactive oxygen species (ROS) regulation in bleomycin (BLM)-induced IPF mice. The mice were intratracheally injected with BLM (3 mg/kg) and L-carnosine (150 mg/kg) was orally administrated for 2 weeks. BLM exposure increased the protein level of Nox2, Nox4, p53, and Caspase-3, whereas L-carnosine treatment suppressed the protein level of Nox2, Nox4, p53, and Caspase-3 cleavage in mice. In addition, the total SOD activity and mRNA level of Sod2, catalase, and Nqo1 increased in mice treated with L-carnosine. At the cellular level, a human fibroblast (MRC-5) and mouse alveolar epithelial cell (MLE-12) were exposed to TGFβ1 following L-carnosine treatment to induce fibrogenesis. Moreover, MLE-12 cells were exposed to cigarette smoke extract (CSE). Consequently, L-carnosine treatment ameliorated fibrogenesis in fibroblasts and alveolar epithelial cells, and inflammation induced by ROS and CSE exposure was ameliorated. These results were associated with the inhibition of the NFκB pathway. Collectively, our data indicate that L-carnosine induces anti-inflammatory and anti-fibrotic effects on alveolar epithelial cells against the pathogenesis of IPF.

Preparation and Characterization of an Ancient Aminopeptidase Obtained from Ancestral Sequence Reconstruction for L-Carnosine Synthesis

As a biologically active peptide, L-carnosine has been widely used in the pharmaceutical, cosmetic and health care industries due to its various physiological properties. However, relatively little research is available regarding L-carnosine's enzymatic synthesis function. In this study, a potential enzyme sequence with the function of carnosine synthesizing was screened out using the ancestral sequence reconstruction (ASR) technique. Identified with L-carnosine synthesis activity, this enzyme was further confirmed using autoproteolytic phenomenon via Western blot and N-terminal sequencing. After purification, the enzymatic properties of LUCA-DmpA were characterized. The melting temperature (T_m) and denaturation enthalpy (ΔH) of LUCA-DmpA were 60.27 ± 1.24 °C and 1306.00 ± 26.73 kJ·mol^-1, respectively. Circular dichroism (CD) spectroscopy results showed that this ancestral enzyme was composed of α-helix (35.23 ± 0.06%), β-sheet (11.06 ± 0.06%), β-turn (23.67 ± 0.06%) and random coil (32.03 ± 0.06%). The enzyme was characterized with the optimal temperature and pH of 45 °C and 9.0, respectively. Notably, LUCA-DmpA was also characterized with remarkable pH tolerance based on the observation of more than 85% remaining enzymatic activity after incubation at different pH buffers (pH = 6-11) for 12 h. Additionally, rather than being improved or inhibited by metal ions, its enzymatic activity was found to be promoted by introducing organic solvent with a larger log P value. Based on these homology modeling results, the screened LUCA-DmpA is suggested to have further optimization potential, and thereafter to be offered as a promising candidate for real industrial applications.

Carnosine suppresses human colorectal cancer cell proliferation by inducing necroptosis and autophagy and reducing angiogenesis

Carnosine (β-alanyl-L-histidine) is found in beef and fish. The present study aimed to investigate the effects of carnosine on the cell proliferation of human colorectal cancer cells. After human colorectal cancer HCT-116 cells were treated carnosine for 72 or 96 h, the cell proliferation, apoptosis, autophagy, necroptosis, angiogenesis and the expression of related regulatory molecules were detected using MTT assays, fluorescence image analysis and RT-qPCR in this study. Treatment of HCT-116 cells with 5, 10 or 15 mM carnosine for 72 or 96 h significantly decreased cell viability (P<0.05). The mRNA expression of β-catenin and transcription factor 4 (Tcf-4) was significantly reduced by 15–23% and 11–80%, respectively (P<0.05). When HCT-116 cells were treated with 15 mM carnosine, the mRNA levels of 1A/1B-light chain 3 and phosphatidylinositol 3-kinase were significantly increased by 235% and 249%, respectively (P<0.05). The mRNA level of Beclin-1 and autophagy levels were significantly increased by 137–141% in HCT-116 cells treated with 5, 10 or 15 mM carnosine (P<0.05). Carnosine (15 mM) also increased reactive oxygen species levels and mixed lineage kinase domain-like protein mRNA expression and depleted ATP levels (P<0.05). The angiogenesis-regulating molecules vascular endothelial growth factor, epidermal growth factor receptor and hypoxia-inducible factor 1-α were all significantly decreased by 10 or 15 mM carnosine treatment. These results showed that carnosine could suppress human colorectal cell proliferation by reducing β-catenin/Tcf-4 signaling, inducing autophagy and necroptosis and inhibiting angiogenesis. It was demonstrated that carnosine is a potential compound from dietary food for the future clinical treatment and/or prevention of colorectal cancer.

Aluminum chloride induces G0/G1 phase arrest via regulating the reactive oxygen species-depended non-canonical STAT1 pathway in hFOB1.19 cells

Treatment with aluminum chloride (AlCl₃) suppresses the growth of osteoblastic cells; however, the molecular mechanisms underlying the impact of AlCl₃ on cell growth have not been fully characterized. In this study, we observed that exposure of hFOB1.19 cells to AlCl₃ arrested cells at G₀/G₁ phase by inducing p21 expression. Further studies indicated that AlCl₃ upregulated the phosphorylation level of signal transducer and activator of transcription 1 (STAT1) at serine 727 site (Ser727). By chromatin immunoprecipitation and electrophoretic mobility shift assay, we found that AlCl₃ promoted STAT1/DNA binding activity to p21 promoter, thus resulting in the upregulation of p21. Moreover, siRNA-mediated knockdown of STAT1 attenuated p21 level induced by AlCl₃. Notably, using hFOB1.19 cells stably expressing dominant-negative STAT1 (Ser727Ala), we demonstrated that phosphorylation of STAT1 at Ser727 site is required for p21-mediated cycle arrest induced by AlCl₃. Mechanism investigation indicated that AlCl₃ stimulated the phosphorylation of JNK, and administration of JNK inhibitor SP600125 prevented AlCl₃-induced G₀/G₁ arrest through suppressing the phosphorylation of STAT1. Notably, pretreatment with N-acetyl-cysteine, a reactive oxygen species scavenger, conferred a significantly inhibitory effect on AlCl₃-mediated activation of JNK/STAT1 signaling pathway. Taken together, our findings provide the molecular mechanism for G₀/G₁ arrest induced by AlCl₃ in osteoblastic cells.

Erythrocytes Prevent Degradation of Carnosine by Human Serum Carnosinase

The naturally occurring dipeptide carnosine (β-alanyl-l-histidine) has beneficial effects in different diseases. It is also frequently used as a food supplement to improve exercise performance and because of its anti-aging effects. Nevertheless, after oral ingestion, the dipeptide is not detectable in human serum because of rapid degradation by serum carnosinase. At the same time, intact carnosine is excreted in urine up to five hours after intake. Therefore, an unknown compartment protecting the dipeptide from degradation has long been hypothesized. Considering that erythrocytes may constitute this compartment, we investigated the uptake and intracellular amounts of carnosine in human erythrocytes cultivated in the presence of the dipeptide and human serum using liquid chromatography–mass spectrometry. In addition, we studied carnosine’s effect on ATP production in red blood cells and on their response to oxidative stress. Our experiments revealed uptake of carnosine into erythrocytes and protection from carnosinase degradation. In addition, no negative effect on ATP production or defense against oxidative stress was observed. In conclusion, our results for the first time demonstrate that erythrocytes can take up carnosine, and, most importantly, thereby prevent its degradation by human serum carnosinase.

Protective effects of dietary carnosine during in-vitro digestion of pork differing in fat content and cooking conditions

Muscle carnosine represents an important health advantage of meat. Ground pork samples with intrinsic or added carnosine; fat content; and cooked under low or high intensity as a 2 × 2 × 2 factorial were digested in-vitro. Changes in free carnosine and in markers of lipid (hexanal, 4-hydroxynonenal (4-HNE), malondialdehyde (MDA) and protein (protein-carbonyls, thiols) oxidation, and of advanced glycation end-products (AGEs) N^ε -(carboxymethyl)lysine (CML) were determined in the saliva, gastric, and duodenal digests. During digestion, the different markers overall indicated increased oxidation and decreased free carnosine. Increasing pork carnosine level significantly reduced protein carbonyls, loss of thiols, and 4-HNE during in-vitro gastric digestion, irrespective of fat and cooking level of the meat. Increased carnosine also significantly reduced hexanal, MDA and CML up to the duodenum phase in moderately cooked lean pork. Besides substantiating the formation of AGEs during digestion, these results show a potentially important role of dietary carnosine occurring in the gastrointestinal tract. PRACTICAL APPLICATIONS: The ailments epidemiologically associated with red meat consumption could be counteracted by ingesting carnosine into meat. The health advantages of dietary carnosine, however, have never been demonstrated during digestion, a unique and complex oxidative environment compounded by the composition and cooking of the meat. The results obtained substantiated that AGEs formation occurred in-vitro in the GIT. They also showed that increased carnosine had an immediate health beneficial role during pork digestion in reducing the formation of different harmful molecules, including AGEs, modulated by the composition and cooking of the meat. However, in exerting this protective role in the GIT, the remaining free level of carnosine, gradually decreased during digestion. Carnosine, as an important meat compositional factor may, depending on the fat content and cooking conditions, change the image of meat from representing a health risk to a health benefit. Carnosine level may also explain discrepancies observed in the literature.

The Dual-Role of Methylglyoxal in Tumor Progression - Novel Therapeutic Approaches

One of the hallmarks of cancer cells is their metabolic reprogramming, which includes the preference for the use of anaerobic glycolysis to produce energy, even in presence of normal oxygen levels. This phenomenon, known as “Warburg effect”, leads to the increased production of reactive intermediates. Among these Methylglyoxal (MGO), a reactive dicarbonyl known as the major precursor of the advanced glycated end products (AGEs), is attracting great attention. It has been well established that endogenous MGO levels are increased in several types of cancer, however the MGO contribution in tumor progression is still debated. Although an anti-cancer role was initially attributed to MGO due to its cytotoxicity, emerging evidence has highlighted its pro-tumorigenic role in several types of cancer. These apparently conflicting results are explained by the hormetic potential of MGO, in which lower doses of MGO are able to establish an adaptive response in cancer cells while higher doses cause cellular apoptosis. Therefore, the extent of MGO accumulation and the tumor context are crucial to establish MGO contribution to cancer progression. Several therapeutic approaches have been proposed and are currently under investigation to inhibit the pro-tumorigenic action of MGO. In this review, we provide an overview of the early and latest evidence regarding the role of MGO in cancer, in order to define its contribution in tumor progression, and the therapeutic strategies aimed to counteract the tumor growth.

Methylglyoxal Scavengers Resensitize KRAS-Mutated Colorectal Tumors to Cetuximab

The use of cetuximab anti-epidermal growth factor receptor (anti-EGFR) antibodies has opened the era of targeted and personalized therapy in colorectal cancer (CRC). Poor response rates have been unequivocally shown in mutant KRAS and are even observed in a majority of wild-type KRAS tumors. Therefore, patient selection based on mutational profiling remains problematic. We previously identified methylglyoxal (MGO), a by-product of glycolysis, as a metabolite promoting tumor growth and metastasis. Mutant KRAS cells under MGO stress show AKT-dependent survival when compared with wild-type KRAS isogenic CRC cells. MGO induces AKT activation through phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin 2 (mTORC2) and Hsp27 regulation. Importantly, the sole induction of MGO stress in sensitive wild-type KRAS cells renders them resistant to cetuximab. MGO scavengers inhibit AKT and resensitize KRAS-mutated CRC cells to cetuximab in vivo. This study establishes a link between MGO and AKT activation and pinpoints this oncometabolite as a potential target to tackle EGFR-targeted therapy resistance in CRC.

Identification of Metabonomics Changes in Longissimus Dorsi Muscle of Finishing Pigs Following Heat Stress through LC-MS/MS-Based Metabonomics Method

Simple Summary

Limited research exists on muscle metabolomics of finishing pigs under heat stress. In this study, nine different metabolites in the longissimus dorsi (LD) muscle of finishing pigs under heat stress were screened and identified. Through quantitative verification, it was concluded that the content of L-carnitine in the LD muscles of the finishing pigs could be significantly decreased due to heat stress, which might be a biomarker for monitoring the animal health status and muscle quality under heat stress.

Abstract

Heat stress (HS) negatively affects meat quality by affecting material and energy metabolism, and exploring the mechanism underlying the muscle response to chronic HS in finishing pigs is important for the global pork industry. This study investigated changes in the metabolic profiles of the longissimus dorsi (LD) muscle of finishing pigs under high temperature using ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS) and multivariate data analysis (MDA). Castrated male DLY pigs (Duroc × Landrance × Yorkshire pigs, n = 24) from 8 litters were divided into three treatment groups: constant optimal ambient temperature at 22 °C and ad libitum feeding (CR, n = 8); constant high ambient temperature at 30 °C and ad libitum feeding (HS, n = 8); and constant optimal ambient temperature 22 °C and pair-feeding to the control pigs (PF, n = 8). The metabolic profile data from LD muscle samples were analyzed by MDA and external search engines. Nine differential metabolites (L-carnosine, acetylcholine, inosinic acid, L-carnitine, L-anserine, L-α-glycerylphosphorylcholine, acetylcarnitine, thiamine triphosphate, and adenosine thiamine diphosphate) were involved in antioxidant function, lipid metabolism, and cell signal transduction, which may decrease post mortem meat quality and play important roles in anti-HS. Four metabolites (L-carnosine, acetylcholine, inosinic acid, and L-carnitine) were verified, and it was indicated that the muscle L-carnitine content was significantly lower in HS than in CR (p < 0.01). The results show that constant HS affects the metabolites in the LD muscle and leads to coordinated changes in the endogenous antioxidant defense and meat quality of finishing pigs. These metabonomics results provide a basis for researching nutritional strategies to reduce the negative effects of heat stress on livestock and present new insights for further research.

Radio-selective effects of a natural occurring muscle-derived dipeptide in A549 and normal cell lines

Radiotherapy (RT) causes morbidity and long-term side effects. A challenge in RT is to maximize cancer cells killing while minimizing damage to normal tissue. The ideal radio-protector selectively improves survival and limits damage to normal tissues while reducing survival of cancer cells. Muscle-derived dipeptide, L-carnosine (CAR) is a potent antioxidant, with radio-protective, but also anticancer properties, affecting the cell cycle of cancer cells. We tested CAR effects in lung cancer cells, differentiated and undifferentiated normal cells. We hypothesized that CAR antioxidant properties will confer protection to the two normal cell lines against RT, while preventing lung cancer cell proliferation, and that CAR may act as a radiosensitizer of lung cancer cells due to its effects on cell-cycle progression of cancer cells. Under the experimental conditions reported here, we found that CAR increased radio-sensitivity of lung (A549) cancer cells by increasing the percentage of cells in G2/M (radiosensitive) phase of cell cycle, it negatively affected their bioenergetics, therefore reduced their viability, and DNA-double strand break repair capacity. CAR had either no effect or reduced RT-induced damage in normal cells, depending on the cell type. CAR is a versatile natural occurring compound, that could improve RT-induced lung cancer cells killing, while reducing the damage to normal differentiated and undifferentiated cells.