Search Results (4,497)

Background/Objectives: T cells within solid tumors often switch from a recirculating to a tissue-resident state, which may blunt antitumor activity, but the signal driving this switch in vivo remains unclear. We asked whether alterations in sphingosine-1-phosphate (S1P) signaling in tumor or the surrounding stromal cells are associated with T cell residency in glioblastoma (GBM). Methods: We analyzed five single-cell RNA-sequencing cohorts: three human glioma datasets, an in-house mouse CT2A glioblastoma cohort, and a human melanoma tumor-infiltrating lymphocyte cohort. T cell egress and tissue-residency programs, together with stromal S1P production and degradation, were scored per cell using curated gene modules. Cell-state contrasts were quantified as Cohen’s d, and sample-level coupling as Spearman ρ. Results: In human GBM, T cell residency programs were elevated in CD4+ helper and regulatory T cells in tumors compared with low-grade glioma controls. In mouse CT2A-derived GBM tumors, stromal S1P production correlated negatively with T cell residency across four independent stromal cell types. In human GBM microglia, S1P production was reduced compared with control microglia. The same CD8+ residency phenotype was replicated in CD3-sorted GBM tumor-infiltrating lymphocytes (TILs) and in melanoma TILs. Conclusions: A loss of stromal S1P production accompanies T cell tissue residency in GBM. Thus, stromal S1P metabolism is a candidate axis for modulating T cell recirculation and TIL biology in GBM. These findings are transcriptomic associations from single-cell RNA sequencing that do not directly measure S1P metabolite levels or signaling activity and will require functional and lipidomic validation. Full article

Melanoma incidence is steadily on the rise but widespread prevention awareness and novel treatment approaches have substantially ameliorated the prognosis of the disease. Microphthalmia-associated transcription factor (MITF) is an essential transcription factor that plays a central role in the transcriptional circuitry of both normal melanocytes and malignant melanoma. Since over 30 years have elapsed since its discovery in mice, a large number of its target genes have been identified in pigment cells. Many upstream regulators of MITF have also been identified. Despite these substantial discoveries, MITF function, especially in melanomas, still remains elusive in several aspects. MITF is absolutely required for melanin formation because it transcribes virtually all genes required for the synthesis, storage, and transport of the pigment. Importantly, MITF is necessary for prevention of apoptosis in melanomas, at least at the early stages. However, in some metastases, MITF may be absent in most cells and its antiapoptotic function is evidently replaced by other proteins that not yet been fully identified. Furthermore, MITF is a specific nevus and melanoma marker, which is routinely used in immunohistochemistry, along with other markers, to distinguish pigmented and other skin lesions. In melanomas, high-MITF melanoma cell subpopulations are considered differentiated, i.e., pigmented and rapidly proliferating. In contrast, low-MITF cells proliferate slowly but are invasive with cancer stem cell-like properties. Although MITF activates mostly antiapoptotic and pro-proliferative genes, it also activates typical cell cycle inhibitors such as the p16 and p21 proteins. Here we discuss the issues of MITF multifunctionality in melanoma and associated research prospects. Full article

Unc-51-like kinase 3 (ULK3) is a key member of the ULK serine/threonine kinase family. Aberrant ULK3 expression has been increasingly linked to tumorigenesis and malignant progression in multiple cancer types. However, the precise role of ULK3 in tumor initiation and progression remains incompletely understood. Leveraging integrated multi-omics data from The Cancer Genome Atlas (TCGA), the Genotype-Tissue Expression (GTEx) project, and the Clinical Proteomic Tumor Analysis Consortium (CPTAC), we systematically characterized the expression of ULK3 at both the transcript and protein levels across 33 cancer types. We also evaluated genomic alterations, prognostic significance, alternative splicing, pathway enrichment, tumor stemness, immune infiltration, and immunotherapy-related biomarkers. In parallel, we investigated the function of ULK3 in prostate cancer PC-3 cells using cellular localization analysis, wound-healing assays, and MTT assays. We further applied Connectivity Map (CMap) screening and molecular docking to identify candidate ULK3 activators. ULK3 was significantly upregulated in 13 cancer types, including Bladder Urothelial Carcinoma, Breast Invasive Carcinoma, and Lung Adenocarcinoma. In contrast, ULK3 was downregulated in Cholangiocarcinoma and Head and Neck Squamous Cell Carcinoma. High ULK3 expression was associated with poor overall survival in Adrenocortical Carcinoma, Kidney Renal Clear Cell Carcinoma, and Skin Cutaneous Melanoma. Copy number amplification contributed to ULK3 overexpression. A recurrent A206V missense mutation was detected in the protein kinase (Pkinase) domain. Genes co-expressed with ULK3 were enriched in RNA splicing, methylation, oxidative phosphorylation, and energy metabolism. ULK3 expression showed positive correlations with tumor stemness indices and m1A/m5C/m6A RNA modification regulators. From an immunological perspective, high ULK3 expression was associated with lower Immune Score, increased M2 macrophage infiltration, and co-expression of PD-L1, CTLA4, and LAG3 in most cancers. ULK3 expression was also correlated with Tumor Mutational Burden in Kidney Renal Clear Cell Carcinoma and Rectum Adenocarcinoma. In addition, ULK3 expression was associated with Microsatellite Instability in Brain Lower Grade Glioma, Lung Adenocarcinoma, and Uterine Corpus Endometrial Carcinoma. ULK3 overexpression promoted proliferation and migration in PC-3 cells. Cephaeline was screened as a putative ULK3 activator. Overall, ULK3 expression and amplification were associated with poor clinical outcomes, tumor stemness, immunosuppression, and RNA dysregulation. These findings highlight the potential value of ULK3 as a pan-cancer diagnostic and prognostic biomarker and as a predictor of immunotherapy response, particularly in prostate cancer. Full article

Background/Objectives: Malignant melanoma is characterized by constitutive PI3K/Akt/mTOR and MAPK activation, driving aggressive behavior and therapeutic resistance. Alpha-lipoic acid (αLA), a naturally occurring dithiol compound with an established clinical safety profile, has shown anticancer potential; however, its integrated molecular mechanisms in melanoma remain poorly defined. This study aimed to comprehensively evaluate the cytotoxic and mechanistic effects of αLA in B16F10 murine melanoma cells. Methods: Antiproliferative effects were assessed by MTT assay at four concentrations (250, 500, 750, 1000 µM) over 48 h. Protein levels of apoptotic markers (Bax, Bcl-2, Caspase-3, AIF), kinase signaling components (p-Akt, p-mTOR, p-ERK, p-JNK), ER stress markers (GRP78, GADD153/CHOP), and cell cycle regulator Wee1 were quantified by ELISA at a specifically selected sub-lethal concentration of 750 µM (inducing ~38% growth inhibition). Results: αLA dose-dependently inhibited B16F10 proliferation. At 750 µM, it triggered robust intrinsic apoptotic signaling, evidenced by a nearly 10-fold shift in the Bax/Bcl-2 ratio and greater than 9-fold Caspase-3 activation. Elevated AIF suggested profound mitochondrial stress and the potential priming of concurrent caspase-independent cell death mechanisms. αLA suppressed survival signaling by reducing p-Akt (44%), p-mTOR, p-ERK, and p-JNK. Treatment triggered lethal ER stress via GRP78 and GADD153/CHOP upregulation and upregulated Wee1, suggesting the induction of stress-responsive checkpoint signaling. The simultaneous CHOP upregulation and p-Akt suppression highlight a concurrent dysregulation of stress and survival pathways, suggesting a potential pro-apoptotic interplay. Conclusions: αLA exerts potent multi-target anticancer effects by inducing a broad spectrum of associated molecular changes, including the suppression of PI3K/Akt/mTOR and MAPK networks, induction of ER stress, engagement of cell cycle checkpoints, and activation of the mitochondrial Bax/Bcl-2/Caspase-3 axis. Importantly, these correlative findings do not establish proven pathway dependencies. Nevertheless, this concurrent dysregulation positions αLA as a potential disruptor of inter-pathway resilience underlying drug resistance. Full article

Melanoma remains highly lethal with frequent resistance to current therapies. Here we identify a marine-derived cyclopentapeptide, turnagainolide B, as a potent anti-melanoma agent that selectively kills B16-F10 melanoma cells (IC₅₀ = 50 μM) with low toxicity to normal skin cells. Using bioassay-guided isolation, we also obtained a new analogue, turnagainolide H, and elucidated their structures and biosynthetic pathways. Mechanistically, turnagainolide B induces a previously undescribed “dual-hit” autophagic signature: it simultaneously promotes autophagy initiation (via PI3K/mTOR suppression, evidenced by ATG5 and LC3B-II upregulation) and blocks autophagic degradation (evidenced by p62 accumulation). Co-treatment with chloroquine partially rescued cell viability and decreased LC3B levels, confirming that cell death depends on active autophagic flux disruption. Transcriptomic analysis, together with AI target prediction and docking, identified PI3K as a potential direct target, with downregulation of PI3K, mTOR, and BNIP3 supporting an imbalanced autophagic state. In a syngeneic mouse melanoma model, turnagainolide B significantly suppressed tumor growth, reduced melanin content and Ki67 expression, and enhanced CD8⁺ T cell infiltration. Collectively, this work expands the chemical diversity of the turnagainolide family, uncovers a unique “dual-hit” autophagic mechanism, and establishes turnagainolide B as a promising lead for melanoma therapy. Full article

Background and Clinical Significance: Cutaneous squamous cell carcinoma (CSCC) is a common non-melanoma skin cancer, and while most cases are curable, a small proportion progresses to locally advanced or metastatic disease. As neoadjuvant immunotherapy with PD-1 inhibitors such as cemiplimab becomes more widely adopted, understanding real-world patterns of response remains essential. Case Presentation: We report a case of a man in his 50s with a large, locally advanced CSCC of the left hand in whom neoadjuvant cemiplimab was chosen to reduce tumor burden and preserve hand function when margin-negative resection was unlikely. The patient received four cycles of cemiplimab and demonstrated marked clinical improvement followed by complete pathological response at the primary site upon wide local excision. However, metastatic involvement of the epitrochlear and axillary lymph nodes was identified at surgery despite initial benign imaging. Postoperative PET/CT showed no additional disease, and the patient subsequently underwent axillary dissection and adjuvant cemiplimab with good functional recovery. Conclusions: This case highlights the potential for neoadjuvant cemiplimab to achieve substantial local tumor control and functional preservation while emphasizing the need for careful nodal assessment and ongoing surveillance in patients with very-high-risk CSCC. In cases where baseline cross-sectional staging is not performed, pre-existing occult nodal disease cannot be excluded. Full article

Drug repurposing represents a rational and resource-efficient strategy to expand the oncological armamentarium by leveraging the established pharmacology, clinical experience, and safety-monitoring frameworks of approved non-oncological agents. Clozapine (CZP), an atypical antipsychotic characterized by broad receptor pharmacology, complex biotransformation, and clinically relevant toxicological liabilities, has emerged as a candidate of interest following preclinical evidence of context-dependent anticancer activity across multiple tumor types. As such, CZP provides an informative case study at the interface between therapeutic drug action and xenobiotic behavior. This review provides a critical and integrated synthesis of the current evidence supporting the repurposing of CZP in oncology, with particular emphasis on the relationship between its molecular mechanisms, dose–exposure requirements, pharmacological complexity, and potential toxicity. Analysis of in vitro and in vivo studies across glioblastoma, non-small cell lung cancer, breast cancer, and melanoma brain metastasis models indicates that CZP can impair tumor cell proliferation and survival through a form of mechanistic plasticity. Rather than acting through a single conserved pathway, CZP appears to disrupt shared upstream processes related to pro-survival signaling, cellular stress tolerance, and metabolic homeostasis, while engaging tumor-specific downstream responses, including autophagic cell death, mitochondria-dependent apoptosis, oxidative stress, and coordinated modulation of survival and angiogenic pathways. Despite this mechanistic rationale, translation remains substantially constrained, most notably by the order of magnitude gap between anticancer-effective concentrations in vitro and clinically achievable plasma exposures, requiring careful distinction between potentially useful anticancer pharmacology and nonspecific xenobiotic-induced cellular stress and clinically unacceptable toxicity. Key limitations include the discrepancy between anticancer-effective concentrations observed in vitro and exposures achievable during standard psychiatric dosing, the limited understanding of how CZP metabolism and metabolite formation may influence efficacy and toxicity, the absence of integrated pharmacokinetic–pharmacodynamic and toxicokinetic modeling, and the lack of dedicated clinical trial evidence. To address these challenges, this review examines complementary translational strategies, including patient-derived organoids, co-culture systems, microphysiological platforms, pharmacokinetic and toxicological modeling, and computational digital twin frameworks. Together, these approaches may support a biologically informed and risk-aware evaluation of CZP, helping to identify responsive tumor contexts, anticipate exposure-related liabilities, and prioritize rational combination strategies. By integrating therapeutic potential with xenobiotic pharmacology and toxicology, this review positions CZP within the evolving landscape of precision oncology and evidence-driven drug repurposing. Full article

Nutraceuticals are bioactive compounds that can contribute to maintaining general health and supporting the treatment of various conditions. Among them, flavonoids such as curcumin (C) and quercetin (Q) are of particular interest in oncology research, including melanoma, due to their anti-tumor effects. However, due to poor bioavailability, the development of efficient delivery vehicles is of utmost importance. In this context, we aimed to assess the effectiveness of a potential treatment on the progression of cutaneous melanoma by evaluating cell viability and proliferation in the presence of encapsulated C/Q in innovative microcapsules (MDDS) embedded in a collagen matrix, as well as the anti-inflammatory and antioxidant potential. We found that tumor cell viability and proliferation were significantly reduced in the presence of C/Q, with the best results being obtained for the composite with both bioactive compounds, these results were also supported by a significant increase in pro-apoptotic markers. A decrease in pro-inflammatory markers was observed, as well as a decrease in ROS secretion over time, indicating the anti-inflammatory and antioxidant potential of the materials supplemented with the tested flavonoids, these properties being important for TME modulation. Therefore, the MDDS-CQ embedded sponge could represent a potential adjuvant therapy for cutaneous melanoma in the future. Full article

Background and Objectives: A subset of cancer patients treated with immune checkpoint inhibitors may experience rapid tumor progression rather than therapeutic benefit, a phenomenon described as hyperprogressive disease (HPD), which is linked to poor prognosis and shortened survival. Reliable biomarkers capable of predicting HPD remain lacking. To better understand the molecular background of HPD, we analyzed promoter region methylation and somatic mutation profiles in cancer-related genes in patients with malignant melanoma (MM) and renal cell carcinoma (RCC) undergoing anti-PD-1/PD-L1 treatment. Methods: Patients diagnosed with MM or RCC and treated with anti-PD-1/PD-L1 agents between 2011 and 2020 were included, and FFPE tumor samples along with paired normal tissues were analyzed. A diagnosis of HPD was assigned to patients with RECIST 1.1-defined progressive disease who demonstrated a ≥2-fold acceleration in tumor growth kinetics after initiation of immune checkpoint inhibitor therapy. Methylation-specific real-time PCR was performed on 54 samples (15 MM tumors, 22 RCC tumors, 17 RCC-matched adjacent normal samples) to assess promoter methylation of PIK3CA, BAP1, PTEN, and TP53. Next-generation sequencing (NGS) with an 86-gene pan-cancer panel was conducted on 9 HPD samples. Results: Promoter hypermethylation involving PIK3CA, BAP1, PTEN, and TP53 was more pronounced in HPD-associated tumor samples (n = 16) than in tumors without HPD (n = 21). Within the MM cohort, PTEN and TP53 methylation levels demonstrated statistically significant differences between the two groups (p = 0.005 and p = 0.028, respectively), while no comparable associations were observed in RCC patients. NGS analysis detected missense mutations classified as pathogenic or likely pathogenic in 5 of 9 HPD patients (55.6%), involving KIT, PTEN, and VHL. Conclusions: Promoter region hypermethylation in cancer-related genes may contribute to the aggressive tumor behavior observed in HPD. The somatic variants identified in HPD patients are consistent with known oncogenic pathways. These findings support further investigation of epigenetic and genomic biomarkers for HPD risk stratification in larger, prospective cohorts. Full article

Recent studies report inverse relationships between the incidence of Alzheimer’s Disease (AD) and certain malignancies, including melanoma. This has encouraged research into factor(s) in AD that can exert antitumor effects. Presenilin-1 (PS-1) is part of the enzymatic complex that cleaves amyloid precursor protein (APP) into amyloid-beta (Aβ) products that are linked to the neuronal damage seen in AD. PS-1 can also degrade β-catenin and reduce the effectiveness of the “wingless-related integration” (WNT) signaling pathway. Little is known about the relationship between the AD microenvironment, PS-1, and melanoma. We hypothesize that melanoma growth in AD depends on the degree of PS-1-dependent processing of APP into cytotoxic Aβ by melanoma cells. To determine how melanoma reacts to an APP-rich, AD-like microenvironment, PS-1-high (WM1552C) and PS-1-low (C8161) melanoma cells were treated with soluble recombinant human APP (rhAPP). We found that rhAPP treatment significantly reduced cellular activity in WM1552C but not in C8161 cells. Moreover, Aβ products were significantly higher in conditioned media from rhAPP-treated WM1552C compared to controls. Treatment with PS-1 inducing DAPT or PS-1 function inhibiting MRK-560 reversed the effects of rhAPP treatment, respectively in C8161 and WM1552C cells. Furthermore, we found that migration of WM1552C was significantly reduced in the presence of either soluble rhAPP or mouse AD brain tissue, compared to C8161, suggesting that in WM1552C the combination of PS-1 activity and the presence of APP/Aβ in the microenvironment interferes with cell migration. In summary, PS-1 function may predict how melanoma will grow in an APP/Aβ-rich microenvironment, such as AD. Full article

Immune checkpoint inhibitors (ICIs), comprising anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), anti-programmed cell death protein 1 (PD-1), and anti-programmed death-ligand 1 (PD-L1), have transformed melanoma therapy, yet the tumour microenvironment (TME), the pivotal biological interface where therapeutic efficacy, resistance, and toxicity are determined, remains incompletely characterized. This dual systematic review and meta-analysis (PROSPERO: CRD420261374242) followed PRISMA 2020 and included 58 preclinical (B16F10/C57BL/6; 46 quantitative) and 44 clinical studies (19 quantitative) to calculate pooled standardized mean differences (SMDs) for six intratumoral TME parameters. Checkpoint blockade consistently shifted the TME toward an immune-activated state, an effect that remained robust in sensitivity analyses despite substantial heterogeneity (I-squared heterogeneity statistic (I²) = 68–88%). Preclinically, ICIs significantly increased CD8⁺ T-cell infiltration (SMD = 1.45, p < 0.001), interferon-gamma (IFN-γ) (SMD = 1.78, p < 0.001), CD8/regulatory T-cell (Treg) ratio (SMD = 0.91, p = 0.005), and apoptosis (SMD = 3.54, p < 0.001) and reduced PD-L1 (SMD = −0.88, p = 0.004) and Ki-67 (SMD = −1.43, p = 0.028). Clinically, CD8⁺ infiltration and PD-L1 both increased (SMD = 0.72, p < 0.001; SMD = 0.67, p = 0.001), contrasting with the preclinical PD-L1 decrease. Meta-regression demonstrated superior anti-PD-L1 efficacy over CTLA-4 for effector parameters: IFN-γ +3.59 (p = 0.009), CD8/Treg +10.69 (p = 0.003), apoptosis +9.76 (p = 0.004), and Ki-67 −6.28 (p = 0.040). These findings establish the TME as a critical determinant of ICI outcomes, indicate that PD-L1 amplifies effector functions in the B16F10 model, and highlight translational gaps in TME reprogramming. Full article

Background: Oncolytic viruses (OVs), a promising anti-cancer therapeutic, replicate more efficiently in cancer cells rather than in healthy cells due to the alterations in antiviral response mechanisms and dysregulation of signaling pathways. Vesicular stomatitis virus (VSV) is known for low pathogenicity, tropism to various cancer cells, and the ability to lyse cells in the hypoxic tumor microenvironment (TME). Targeted delivery of immune checkpoint and co-stimulatory molecules can enhance the anti-tumor immune response and remodel the immunosuppressive TME. The aim of this study was to compare the activity of rVSV-GFP with rVSV, encoding the programmed cell death protein 1 (PD-1) and tumor necrosis factor ligand superfamily member 9 (4-1BBL). Methods: The oncolytic efficacy of these rVSV variants used at 10⁵, 10⁶, and 10⁷ TCID50 was evaluated at 24 and 48 h post-infection by flow cytometry in a panel of mouse and human cancer cell lines. Quantitative real-time polymerase chain reaction (qPCR) was used to evaluate mRNA expression levels of certain genes at 12 and 48 h post-infection. Results: Murine hepatocellular carcinoma (H22) and human melanoma (A375) or human lung carcinoma (A549) were the most sensitive to rVSV therapy cell lines. The higher relative expression of the antiviral response genes RIG-I and IFIT1 within each biological species (mouse or human) correlated with lower sensitivity to rVSV. No such effect was observed for the type I interferons (IFNs), despite their proposed key role in resistance to OV therapy. Conclusions: H22, A375, and A549 are more susceptible to the oncolytic activity of the novel rVSV-PD-1-4-1BBL. Full article

Transposable elements (TEs) play important roles during development and disease, including through transcriptional activation of TE-associated genes during early human development. Moreover, based on the functional and epigenetic similarities between early development and cancer, TE-associated genes contribute not only to early human development, but frequently contribute to cancer progression. In this study, we hypothesised that recruitment of TE-associated genes during cancer onset occurs through epigenetic regulatory processes, especially involving DNA hypomethylation accompanied by transcriptional upregulation of early developmental pathways, such that, when reactivated inappropriately in later life, they may drive malignancy. It is unknown, however, to what extent DNA methylation changes are critically involved in the transcriptional activation of TE-associated genes. Accordingly, to investigate this we used the RepExpress tool to identify developmentally regulated TE-associated genes in placenta and human embryonic stem cells (hESCs), which we then investigated by targeted deep bisulfite sequencing (TDBS) to determine the methylation status of the identified TE-associated genes in placenta, somatic tissues, and melanoma cell lines. Outcomes suggest that DNA methylation may be one of the regulatory factors underscoring transcriptional activation of TE-associated genes, but that methylation is not necessarily the sole factor involved in regulating the transcriptional activation of TE-associated genes during malignant transformation. Full article

Background/Objectives: Melanoma affects both sexes, and its incidence has increased in recent years. It is currently among the most common types of cancer. Standard chemotherapy, although effective, often lacks selectivity for tumor cells, resulting in dose-limiting side effects. Electrochemotherapy and magnetic hyperthermia have been investigated as innovative biomedical approaches. Electrochemotherapy improves drug delivery by facilitating electroporation, thereby increasing intracellular concentrations of chemotherapeutic agents and reducing associated adverse effects. Furthermore, electroporation enhances sensitivity to magnetic hyperthermia. However, few studies have focused on the combination of electroporation and hyperthermia in melanoma models. This study aimed to evaluate the synergistic effects of intratumoral administration of superparamagnetic iron oxide nanoparticles (SPIONs), electroporation (EP), and magnetic hyperthermia (EHP) on fluorescent melanoma tumors generated with the MV3-GFP cell line. Methods: Fluorescent melanoma tumors were generated using the MV3-GFP cell line. Treatments included SPIONs alone, SPIONs combined with hyperthermia, and SPIONs combined with electroporation and hyperthermia. Tumor size was monitored over 21 and 28 days. Results: SPIONs alone did not affect tumor growth (665 mm³). SPIONs plus hyperthermia reduced tumor size to 126.5 mm³ at day 21. The combination of SPIONs, electroporation, and hyperthermia produced a pronounced antitumoral effect, with tumor size decreasing to 95.5 mm³ at day 14 and 6.8 mm³ at day 21, followed by complete tumor disappearance by day 28. Electroporation significantly enhanced the antitumoral activity of the combined treatment. Conclusions: The combination of SPIONs, electroporation, and magnetic hyperthermia shows significant synergistic antitumoral activity in a melanoma model. These findings support further investigation in larger and more comprehensive in vivo studies to better understand the therapeutic potential of these combined approaches. Full article

Multifunctional drugs represent an emerging strategy for treating complex skin disorders and melanoma. A series of benzothiazole-based hybrids incorporating gallic and syringic acid moieties was synthesized and evaluated as multifunctional agents for skin-related applications. Six hydrazone (GAHYDR1–3) and acyl-hydrazone (GACIN1–3) derivatives were obtained and fully characterized. Hydroxylated compounds showed the strongest antioxidant activity, with GAHYDR1 and GACIN1 displaying low DPPH IC₅₀ values and high FRAP reducing power. UV–Vis studies revealed strong UVA–UVB absorption, with molar extinction coefficients comparable to or exceeding those of PBSA. Photoprotective evaluation showed SPF values up to 10.09 (GACIN2) and broad-spectrum behavior for selected derivatives. Antioxidant activity remained substantially stable over 3 months in solution. Antiproliferative assays against Colo38, A375, and HaCaT cell lines indicated generally low cytotoxicity toward non-tumor cells. Notably, GAHYDR3 exhibited selective activity against A375 melanoma cells (IC₅₀ = 8.75 µM; SI = 8.12). Overall, phenolic substitution emerged as a key determinant of biological activity, highlighting hydroxylated benzothiazole hybrids as promising antioxidant and photoprotective agents, with GAHYDR3 representing a potential lead for anti-melanoma development. Full article