Background: Colorectal and pancreatic cancers remain therapeutically challenging, with limitations in efficacy and limitations due to toxicity from conventional antimetabolites such as 5-fluorouracil (5-FU), methotrexate (MTX), and gemcitabine (GEM). Steroidal conjugation offers an approach to enhance selectivity and toxicokinetics. Methods: Five novel hybrid homo-aza (lactam) steroidal antimetabolites (GE23, CS18, CS23, KA44, MV16) were synthesized and tested against three pancreatic and four colorectal carcinoma cell lines with distinct molecular characteristics. Antiproliferative activity (MTT), apoptosis (Annexin V/PI), and cell cycle effects were assessed. Thymidylate synthase (TS) and dihydrofolate reductase (DHFR) inhibition was examined via molecular docking, Western blot, and enzymatic assays. Correlations between docking binding scores (DBS) and biological data were analyzed, and effects were compared with reference drugs (5-FU, MTX, GEM). Results: CS23, CS18, and KA44 exhibited the most potent cytostatic activity (mean GI50 10–80 µM). CS23 also induced high cytocidal effects, strong apoptosis (40% at 72 h), and G1/S arrest. Moreover, docking predicted the high binding affinity of CS23 for both TS (−11.2 kcal/mol) and DHFR (−11.5 kcal/mol), which was validated by Western blot and enzymatic inhibition (IC50 ≈ 20 nM). Correlation analyses showed significant relationships between hybrid steroidal antimetabolites’ cytostatic efficacy and DBS for TS (r = −0.75) and DHFR (r = −0.76), and combined DBS values predicted growth inhibition (r = −0.81, p < 0.01). No simple, universal correlation with single mutations of KRAS, BRAF, PI3K, or TP53 was found. Conclusions: Lactam steroidal antimetabolite hybrids, particularly CS23, act as dual TS/DHFR inhibitors, inducing apoptosis and cell cycle arrest with improved selectivity. Their strong in silico–in vitro concordance provides a compelling preclinical rationale for further evaluation of steroidal antimetabolites as next-generation therapeutics for resistant gastrointestinal malignancies.

Glioblastoma (GBM) is the most common and most aggressive malignant primary brain tumor in adults with a median survival of 15 months. One of the main factors responsible for the poor prognosis of GBM is resistance to treatment with temozolomide (TMZ), which has been attributed-among other factors-to autophagy. Preclinical studies have shown that the combination of disulfiram (DSF) with copper (Cu) possesses anti-GBM activity, through various mechanisms, including re-sensitization to TMZ. Herein, we tested for the first time the effects of DSF and Cu in combination with TMZ on the survival of Fischer rats bearing F98 glioma, a model characterized by inherent resistance to TMZ. Tumor size evaluation by Magnetic Resonance Imaging as well as immunofluorescence analysis of two autophagy markers, namely microtubule-associated protein 1 light chain 3 (LC3) and sequestosome-1 (SQSTM1)/p62 (p62), were also performed. According to our results, TMZ-DSF-Cu significantly increased mean survival and induced both LC3 and p62 autophagy markers. Interestingly, these results could not be achieved in the absence of Cu, neither in the presence of TMZ alone, suggesting the importance of combining DSF with Cu in order to sensitize glioma to TMZ, presumably via implication of autophagy modulation.

Despite the use of targeted and/or immune-based therapeutic approaches, mortality rates among melanoma patients are high, mainly due to drug-induced resistance mechanisms. In parallel, alterations of epigenetic mechanisms (e.g., deregulated patterns of DNA methylation, aberrant histone modifications and abnormal expression levels of non-coding RNAs [ncRNAs]) have been associated not only with the pathophysiology of melanoma but also with the resistance against various immunotherapeutic drugs. In this review article, we discuss the involvement of different types of epigenetic mechanisms in melanoma progression. In addition, we report on melanoma's immune environment and immunosuppressive mechanisms while we highlight the role of immune checkpoint inhibitors (ICIs) as an anti-melanoma therapeutic approach. Moreover, we describe the underlying mechanism(s) by which deregulated epigenetic patterns promote drug resistance against ICIs and how epigenetic drugs (utilized either alone or in combination with various ICIs) can reverse immune resistance. Furthermore, we discuss the major limitations and future directions towards clinical translation of epigenetic drugs, mainly in combination with ICIs. Finally, we state the potential use of emerging technologies (e.g., single-cell transcriptomics and spatial transcriptomics), along with epigenetic priming for improvement of clinical implementation and therapeutic outcomes in melanoma management.

Background: In the present study, we aimed to characterize the cytotoxic efficacy of Zebularine either as a single agent or in combination with various isothiocyanates in an in vitro model consisting of human melanoma (A375, Colo-679) as well as non-tumorigenic immortalized keratinocyte (HaCaT) cells. Methods: In this model, we have evaluated the anti-melanoma effect of Zebularine (in single and combinatorial protocols) in terms of cell viability, apoptotic induction and alterations in ultrastructural chromatin configuration, protein expression levels of DNA methyltransferases (DNMTs) and associated histone epigenetic marks capable of mediating gene expression. Results: Exposure to Zebularine resulted in dose- and time-dependent cytotoxicity through apoptotic induction in malignant melanoma cells, while neighboring non-tumorigenic keratinocytes remained unaffected. A more profound response was observed in combinational protocols, as evidenced by a further decline in cell viability leading to an even more robust apoptotic induction followed by a differential response (i.e., activation/de-activation) of various apoptotic genes. Furthermore, combined exposure protocols caused a significant decrease of DNMT1, DNMT3A and DNMT3B protein expression levels together with alterations in ultrastructural chromatin configuration and protein expression levels of specific histone modification marks capable of modulating gene expression. Conclusions: Overall, we have developed a novel experimental approach capable of potentiating the cytotoxic efficacy of Zebularine against human malignant melanoma cells while at the same time maintaining a non-cytotoxic profile against neighboring non-tumorigenic keratinocyte (HaCaT) cells.

BACKGROUND/AIM:This study aimed to characterize the anti-melanoma efficacy of Entinostat (ENT), either as a single agent or in combination with various isothiocyanates (ITCs). MATERIALS AND METHODS:We utilized an in vitro model of human malignant melanoma consisting of melanoma (A375, Colo-679) and immortalized non-tumorigenic keratinocyte (HaCaT) cells. Cytotoxicity was determined using the Alamar blue assay while assessment of apoptosis was determined using a multiplex activity assay (measuring levels of activated caspase 3) as well as using real time-quantitative polymerase chain reaction (RT-qPCR) analysis (determining the expression profile of several apoptotic genes). Protein expression levels of major histone deacetylases (HDACs) were determined using western blotting. RESULTS:ENT caused dose- and time-dependent cytotoxicity against melanoma cells, a response mediated by apoptosis, while non-tumorigenic cells were shown to be more resistant. Also, combined treatment caused a further decline in viability and a more significant induction of apoptosis associated with the reactivation of genes implicated in both intrinsic and extrinsic apoptosis. Moreover, combination treatments further decreased the protein levels of HDAC6 and Sirt1 when compared to the effect of ENT alone. CONCLUSION:We show evidence of an optimized experimental protocol capable of potentiating the anti-melanoma efficacy of ENT while maintaining a non-cytotoxic profile in non-tumorigenic cells.

Aim: During radiation treatment, reactive oxygen species (ROS) and nitrogen species (RNS) are produced and, by extension, DNA adducts known as 8-hydroxy-2′-deoxyguanosine (8-OHdG) and 8-nitroguanine (8-NG), respectively. However, one of the most common side effects induced by radiotherapy is skin toxicity, which affects patients’ quality of life. In the present study, we aimed to investigate the potential predictive value of 8-OHdG and 8-NG by exploring the correlations between the alterations in the concentration levels of the two lesions and radiation-induced tissue injury upon exposure to external beam radiotherapy. Methods: For the purpose of this work, we collected blood serum samples from 33 breast cancer patients who received adjuvant radiotherapy. To conduct statistical analysis, we used: (1) linear adjustment to correlate the percent changes of 8-OHdG and 8-NG with the degree of toxicity; and (2) polynomial adaptation and exponential fitting to correlate the percent changes of 8-OHdG and 8-NG with the correlation coefficient r for the development of radiation dermatitis, respectively. Results: According to our findings, there is a statistically significant correlation between the alterations in the 8-OHdG and 8-NG levels and skin grade toxicity across time and varying radiation doses (p < 0.05). Conclusions: Both DNA lesions seem to possess a promising predictive role in radiation dermatitis, while the severity and exact grade of radiation-induced skin toxicity can be determined.

Malignant melanoma is the most aggressive and lethal type of skin cancer associated with increased mortality rates. Moreover, beyond the genetic background, the altered epigenetic landscape (e.g., abnormal patterns of DNA methylation, aberrant histone modifications and de-regulated expression levels of ncRNAs) further contributes to the pathophysiology of the disease. In addition, despite the improvement of current anti-melanoma strategies and the development of new therapeutic approaches, the 5-year survival among melanoma patients is still high, mainly due to acquired-drug resistance. On the other hand, phytochemicals have been associated with various health-promoting properties through pleiotropic mechanisms including acting as potent epigenetic regulators restoring back a normal phenotype in various experimental cancer models. In this review article, we discuss the general characteristics of malignant melanoma and current therapeutic approaches while we report the epigenetic basis of the disease along with the main compounds capable of restoring a normal epigenetic landscape. Finally, we describe the role of various phytochemicals in targeting the epigenome of malignant melanoma thereby potentially acting as an alternative therapeutic approach.

Metal complexes showing dual activity against cancer and bacterial infections are currently the focus of significant interest for their potential in treating life-threatening diseases. Aiming to investigate the impact of ligand substituents on these bioactivity properties of Group 11 d10 metal complexes, we herein present a series of mononuclear Cu(I) and Ag(I) complexes featuring the bis-NH2-substituted heterocyclic thioamide dap2SH (=4,6-diaminopyrimidine-2-thione), namely [AgCl(dap2SH)(PPh3)2] (1), [CuBr(dap2SH)(PPh3)2] (2), [CuBr (dap2SH)(xantphos)] (3), [Ag(dap2S)(xantphos)] (4), and [Cu(dap2S)(xantphos)] (5) (xantphos = 4,5-bis (diphenylphosphino)-9,9-dimethylxanthene). Complexes were characterized by means of different physicochemical methods (i.e., single crystal X-ray diffraction as well as FTIR, NMR, UV-Vis and fluorescence spectroscopy), and studied in-vitro for their antibacterial and anticancer activity against a variety of bacterial strains and cancer cell lines. Complexes 1-3 effectively inhibited both Gram (+) and Gram (-) bacterial growth, while cellular uptake studies for the most potent complex 1 against E. coli bacteria revealed the accumulation of Ag(I) ions in the periplasm of the bacteria. A high anti-proliferative effect was observed for 1 and 5 against A549, MCF7 and PC3 cancer cell lines, with 1 being capable of inducing apoptosis in A549 cells, as suggested by flow cytometry analysis. DNA interaction studies revealed the capacity of 1 to intercalate between base-pairs of CT DNA. All complexes had a moderate-to-high capacity to scavenge free radicals preventing oxidative stress. Molecular docking calculations, in combination with the experimentally obtained data, provided insights for potential mechanisms of the bioactivity of the complexes.

In this study, we utilized an in vitro model consisting of human malignant melanoma as well as non-tumorigenic immortalized keratinocyte cells with the aim of characterizing the therapeutic effectiveness of the clinical epigenetic drug Tazemetostat alone or in combination with various isothiocyanates. In doing so, we assessed markers of cell viability, apoptotic induction, and expression levels of key proteins capable of mediating the therapeutic response. Our data indicated, for the first time, that Tazemetostat caused a significant decrease in viability levels of malignant melanoma cells in a dose- and time-dependent manner via the induction of apoptosis, while non-malignant keratinocytes were more resistant. Moreover, combinatorial treatment protocols caused a further decrease in cell viability, together with higher apoptotic rates. In addition, a significant reduction in the Polycomb Repressive Complex 2 (PRC2) members [e.g., Enhancer of Zeste Homologue 2 (EZH2), Embryonic Ectoderm Development (EED), and suppressor of zeste 12 (SUZ12)] and tri-methylating lysine 27 at Histone 3 (H3K27me3) protein expression levels was observed, at least partially, under specific combinatorial exposure conditions. Reactivation of major apoptotic gene targets was determined at much higher levels in combinatorial treatment protocols than Tazemetostat alone, known to be involved in the induction of intrinsic and extrinsic apoptosis. Overall, we developed an optimized experimental therapeutic platform aiming to ensure the therapeutic effectiveness of Tazemetostat in malignant melanoma while at the same time minimizing toxicity against neighboring non-tumorigenic keratinocyte cells.

Introduction: Colistin (CMS) is used for the curation of infections caused by multidrug-resistant bacteria. CMS is constrained by toxicity, particularly in kidney and neuronal cells. The recommended human doses are 2.5–5 mg/kg/day, and the toxicity is linked to higher doses. So far, the in vivo toxicity studies have used doses even 10-fold higher than human doses. It is essential to investigate the impact of metabolic response of doses, that are comparable to human doses, to identify biomarkers of latent toxicity. The innovation of the current study is the in vivo stimulation of CMS's impact using a range of CMS doses that have never been investigated before, i.e., 1 and 1.5 mg/kg. The 1 and 1.5 mg/kg, administered in mice, correspond to the therapeutic and toxic human doses, based on previous expertise of our team, regarding the human exposure. The study mainly focused on the biochemical impact of CMS on the metabolome, and on the alterations provoked by 50%-fold of dose increase. The main objectives were i) the comprehension of the biochemical changes resulting after CMS administration and ii) from its dose increase; and iii) the determination of dose-related metabolites that could be considered as toxicity monitoring biomarkers.Methods: The in vivo experiment employed two doses of CMS versus a control group treated with normal saline, and samples of plasma, kidney, and liver were analysed with a UPLC-MS-based metabolomics protocol. Both univariate and multivariate statistical approaches (PCA, OPLS-DA, PLS regression, ROC) and pathway analysis were combined for the data interpretation.Results: The results pointed out six dose-responding metabolites (PAA, DA4S, 2,8-DHA, etc.), dysregulation of renal dopamine, and extended perturbations in renal purine metabolism. Also, the study determined altered levels of liver suberylglycine, a metabolite linked to hepatic steatosis. One of the most intriguing findings was the detection of elevated levels of renal xanthine and uric acid, that act as AChE activators, leading to the rapid degradation of acetylcholine. This evidence provides a naïve hypothesis, for the potential association between the CMS induced nephrotoxicity and CMS induced 39 neurotoxicity, that should be further investigated.

Ionizing radiation is strongly linked to direct or indirect DNA damage, as with the production of reactive oxygen species (ROS), which in turn produce DNA damage products, such as 8-hydroxy-2-deoxyguanosine (8-OHdG). In this study, we aimed to investigate the formation of 8-OHdG after irradiation in patients with non-small cell cancer (NSCLC) and its use as a biomarker. Sixteen patients with squamous and thirty-six patients with non-squamous pathology were included. An enzyme-linked-immunosorbent assay (ELISA) was performed before and after radiation. A dose-dependent relationship was confirmed: 8-OHdG plasma concentrations, increased in the total of NSCLC patients and specifically with a linear correlation in non-squamous pathology; in squamous histology, after an initial increase, a significant decrease followed after 20 Gy dose of irradiation. The pretreatment total irradiated tumor volume (cm3) was positively correlated with 8-OHdG levels in patients with squamous histology. When plotting the 8-OHdG plasma concentration at a 10 Gy irradiation dose to the baseline, the AUC was 0.873 (95% CI 0.614–0.984), p < 0.0001, with an associated criterion value of >1378 as a cutoff (sensitivity 72.7%, specificity 100%). When normalizing this ratio to BSA, the associated criterion cutoff value was >708 (sensitivity of 100%, specificity 80%). Lastly, 8-OHdG levels were closely related with the development of radiation-induced toxicities.

The rubric of immune-related (ir) diabetes mellitus (DM) (irDM) encompasses various hyperglycemic disorders related to immune checkpoint inhibitors (ICPis). Beyond sharing similarities with conventional DM, irDM is a distinct, yet important, entity. The present narrative review provides a comprehensive overview of the literature regarding irDM published in major databases from January 2018 until January 2023. Initially considered rare, irDM is increasingly being reported. To advance the knowledge of irDM, the present review suggests a concerted vision comprising two intertwined aspects: a scientific-centered and a patient-centered view. The scientific-centered aspect addresses the pathophysiology of irDM, integrating: (i) ICPi-induced pancreatic islet autoimmunity in genetically predisposed patients; (ii) altered gut microbiome; (iii) involvement of exocrine pancreas; (iv) immune-related acquired generalized lipodystrophy. The patient-centered aspect is both nurtured by and nurturing the four pillars of the scientific-centered aspect: awareness, diagnosis, treatment, and monitoring of irDM. The path forward is a multidisciplinary initiative towards: (i) improved characterization of the epidemiological, clinical, and immunological profile of irDM; (ii) standardization of reporting, management, and surveillance protocols for irDM leveraging global registries; (iii) patient stratification according to personalized risk for irDM; (iv) new treatments for irDM; and (v) uncoupling ICPi efficacy from immunotoxicity.

Hypothyroidism in the setting of cancer is a puzzling entity due to the dual role of the thyroid hormones (TH) in cancer - promoting versus inhibitory - and the complexity of the hypothyroidism itself. The present review provides a comprehensive overview of the personalized approach to hypothyroidism in patients with solid nonthyroid cancer, focusing on current challenges, unmet needs and future perspectives. Major electronic databases were searched from January 2011 until March 2022. The milestones of the refinement of such a personalized approach are prompt diagnosis, proper TH replacement and development of interventions and/or pharmaceutical agents to exploit hypothyroidism or, on the contrary, TH replacement as an anticancer strategy. Further elucidation of the dual role of TH in cancer - especially of the interference of TH signaling with the hallmarks of cancer - is anticipated to inform decision-making and optimize patient selection.

Alkylating agents are potent anticancer compounds that exert their anticancer properties through the inhibition of cell replication and transcription leading to cell death. Despite the numerous benefits, these agents also have serious drawbacks such as their high toxicity and low specificity towards cancer cells. As previously reported by our group, conjugation of alkylating agents with azasteroids can reduce their systemic toxicity and enhance their anticancer activity. In this work, novel steroidal alkylating agents bearing POPAM-OH were synthesized and their anticancer efficacy was evaluated in vitro and in vivo. All the novel hybrids demonstrated high antiproliferative effects against 5 different cancer cell lines in the low micromolar range. Treatment of SCID mice bearing SKOV-3 or PC-3 tumor xenografts with the most potent hybrid 19 led to significant reduction of tumor size (tumor inhibition TI = 95% in SKOV3 models and TI = 85.2% in PC3 models). Importantly, the acute toxicity of hybrid 19 (LD10 = 36 μΜ, LD50 = 62 μΜ) in CB17 SCID mice exhibited three-fold decrease compared to the acute toxicity of previously reported hybrids of POPAM-NH2. This is an important finding since systemic cytotoxicity is a critical limitation of alkylating agents. Collectively, the steroidal conjugates of POPAM-OH displayed significant anticancer efficacy and reduced toxicity in vitro and in vivo rendering them as good candidates for cancer therapy.

Ag(I) coordination compounds have recently attracted much attention as antiproliferative and antibacterial agents against a wide range of cancer cell lines and pathogens. The bioactivity potential of these complexes depends on their structural characteristics and the nature of their ligands. Herein, we present a series of four Ag(I) coordination compounds bearing as ligands the CH3-substituted thiadiazole-based thioamide 5-methyl-1,3,4-thiadiazole-2-thiol (mtdztH) and phosphines, i.e., [AgCl(mtdztH)(PPh3)2] (1), [Ag(mtdzt)(PPh3)3] (2), [AgCl(mtdztH)(xantphos)] (3), and [AgmtdztH)(dppe)(NO3)]n (4), where xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene and dppe = 1,2-bis(diphenylphosphino)ethane, and the assessment of their in vitro antibacterial and anti-cancer efficiency. Among them, diphosphine-containing compounds 3 and 4 were found to exhibit broad-spectrum antibacterial activity characteristics against both Gram-(+) and Gram-(–) bacterial strains, showing high in vitro bioactivity with IC50 values as low as 4.6 μΜ. In vitro cytotoxicity studies against human ovarian, pancreatic, lung, and prostate cancer cell lines revealed the strong cytotoxic potential of 2 and 4, with IC50 values in the range of 3.1–24.0 μΜ, while 3 and 4 maintained the normal fibroblast cells’ viability at relatively higher levels. Assessment of these results, in combination with those obtained for analogous Ag(I) complexes bearing similar heterocyclic thioamides, suggest the pivotal role of the substituent groups of the thioamide heterocyclic ring in the antibacterial and anti-cancer efficacy of the respective Ag(I) complexes. Compounds 1–4 exhibited moderate in vitro antioxidant capacity for free radicals scavenging, as well as reasonably strong ability to interact with calf-thymus DNA, suggesting the likely implication of these properties in their bioactivity mechanisms. Complementary insights into the possible mechanism of their anti-cancer activity were provided by molecular docking calculations, exploring their ability to bind to the overexpressed fibroblast growth factor receptor 1 (FGFR1), affecting cancer cells’ functionalities.

Malignant melanoma is an aggressive type of skin cancer characterised by high metastatic capacity and mortality rate. On the other hand, Epilobium parviflorum is known for its medicinal properties, including its anticancer potency. In this context, we aimed to (i) isolate various extracts of E. parviflorum, (ii) characterize their phytochemical content, and (iii) determine their cytotoxic potential in an in vitro model of human malignant melanoma. To these ends, we utilized various spectrophotometric and chromatographic (UPLC-MS/MS) approaches to document the higher content of the methanolic extract in polyphenols, soluble sugars, proteins, condensed tannins, and chlorophylls -a and -b as opposed to those of dichloromethane and petroleum. In addition, the cytotoxicity profiling of all extracts was assessed through a colorimetric-based Alamar Blue assay in human malignant melanoma (A375 and COLO-679) as well as non-tumorigenic immortalized keratinocyte (HaCaT) cells. Overall, the methanolic extract was shown to exert significant cytotoxicity, in a time- and concentration-dependent manner, as opposed to the other extracts. The observed cytotoxicity was confined only to human malignant melanoma cells, whereas non-tumorigenic keratinocyte cells remained relatively unaffected. Finally, the expression levels of various apoptotic genes were assessed by qRT-PCR, indicating the activation of both intrinsic and extrinsic apoptotic cascades.

Group 11 metal complexes exhibit promising antibacterial and anticancer properties which can be further enhanced by appropriate ligands. Herein, a series of mononuclear thioamidato Cu(I) and Ag(I) complexes bearing either a diphosphine (P<^>P) or a N -heterocyclic carbene (NHC) auxiliary ligand (L) was synthesized, and the impact of the co-ligand L on the in vitro antibacterial and anticancer properties of their complexes was assessed. All complexes effectively inhibited the growth of various bacterial strains, with the NHC-Cu(I) complex found to be particularly effective against the Gram (+) bacteria (IC50 = 1-4 mu g mL-1). Cytotoxicity studies against various human cancer cells revealed their high anticancer potency and the superior activity of the NHCAg(I) complex (IC50 = 0.95-4.5 mu\M). Flow cytometric analysis on lung and breast cancer cells treated with the NHC-Ag(I) complex suggested an apoptotic cell -death pathway; molecular docking calculations provided mechanistic insights, proving the capacity of the complex to bind on apoptosis-regulating proteins and affect their functionalities.

The synthesis of a novel series of indolyl-2,5-dihydroxybenzoquinone derivatives, analogues of asterriquinones, is reported together with their antiproliferative activity against various carcinoma cell lines, such as A549, MCF7, Hcc827 and PC3. For the synthesis, acid catalyzed reactions of 2,5-diacetoxybenzoquinone with 2-methyl and 1,2-dimethyl indole have been employed. Ten compounds have been tested and exhibited differential activity across the various cell lines. Derivative 7 b was the most cytotoxic with an IC50 value of 25 +/- 2.0 mu M against A549 cancer cells and was more active than cisplatin in PC3 cells (IC50 value of 38 +/- 1.5 mu M). The activity and selectivity of the tested compounds depends both on the number of indole units, the presence of protected hydroxyl groups on 1,4-benzoquinone and N-Me groups on indole.

Watercress is an enriched source of phenethyl isothiocyanate (PEITC), among other phytochemicals, with an antioxidant capacity. The aim of this study was to (i) chemically characterize and (ii) biologically evaluate the profile of the main health-promoting compounds contained in edible (i.e., mixture of leaves and lateral buds) and non-edible (i.e., stems) parts of watercress in an in vitro model of malignant melanoma consisting of human malignant melanoma (A375), non-melanoma (A431) and keratinocyte (HaCaT) cells. The extraction of the main constituents of watercress was performed by subjecting the freeze-dried edible and non-edible samples through different extraction protocols, whereas their concentration was obtained utilizing analytical methodologies. In addition, cell viability was evaluated by the Alamar Blue assay, whereas levels of oxidative stress and apoptosis were determined by commercially available kits. The edible watercress sample contained a higher amount of various nutrients and phytochemicals in the hexane fraction compared to the non-edible one, as evidenced by the presence of PEITC, phenolics, flavonoids, pigments, ascorbic acid, etc. The cytotoxicity potential of the edible watercress sample in the hexane fraction was considerably higher than the non-edible one in A375 cells, whereas A431 and HaCaT cells appeared to be either more resistant or minimally affected, respectively. Finally, levels of oxidative stress and apoptotic induction were increased in both watercress samples, but the magnitude of the induction was much higher in the edible than the non-edible watercress samples. Herein, we provide further evidence documenting the potential development of watercress extracts (including watercress waste by-products) as promising anti-cancer agent(s) against malignant melanoma cells.