Search Results (452)

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 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

Background: Cutaneous squamous cell carcinoma (cSCC) is commonly regarded as a sporadic malignancy primarily driven by ultraviolet exposure. However, the occurrence of multiple, aggressive tumors at a relatively young age suggests the presence of underlying genetic susceptibility. The role of germline variants affecting extracellular matrix organization, pigmentation pathways, and tumor metabolism in aggressive cSCC remains incompletely understood. Case Presentation: We describe a 53-year-old patient with a long-standing history of multiple aggressive cutaneous squamous cell carcinomas involving the scalp and facial regions, characterized by recurrent and multifocal disease. A comprehensive diagnostic approach was undertaken, including histopathological examination, fluorescence confocal microscopy, high-frequency cutaneous ultrasound, and genetic analysis using whole-exome sequencing (WES). Results: Histopathology confirmed high-risk features consistent with aggressive cSCC. Cutaneous ultrasound and fluorescence confocal microscopy provided complementary, non-invasive insights into tumor depth, architecture, and invasive patterns. Whole-exome sequencing identified a heterozygous truncating variant in COL6A3 (NM_004369.4:c.5645C>A, p.Ser1882Ter), classified as likely pathogenic according to ACMG criteria. Additionally, two heterozygous variants of uncertain significance were detected in TYR (NM_000372.5:c.1569C>A, p.Ser523Arg) and FH (NM_000143.4:c.1237-5_1237-4insTCTCCCTCCCTC). Although individually inconclusive, the combined germline genetic background may have contributed to the patient’s aggressive and multifocal cutaneous phenotype. Discussion: This case report supports a potential role of extracellular matrix remodeling, pigmentation-related susceptibility, and metabolic dysregulation in cutaneous carcinogenesis and tumor aggressiveness. This case illustrates how integrating WES with advanced non-invasive imaging techniques can enhance the understanding of biologically aggressive cSCC. Conclusions: This report highlights a unique case of multifocal aggressive cSCC characterized by a distinct germline genetic profile identified by WES and multimodal imaging assessment. Comprehensive molecular and imaging evaluation may be beneficial in selected patients with atypical or aggressive cutaneous squamous cell carcinoma, with implications for personalized surveillance and management. Full article

Background: Actinic keratosis (AK) is a common premalignant skin disorder associated with chronic ultraviolet exposure and a recognized risk of progression to cutaneous squamous cell carcinoma. Tirbanibulin 1% ointment is an effective short-course field therapy for AK, but its efficacy in hyperkeratotic lesions (Olsen grade II–III) may be limited by reduced drug penetration through a thickened stratum corneum. Keratolytic pretreatment may represent a plausible strategy to improve topical drug delivery in these more challenging lesions. Methods: This retrospective chart review included consecutive adults with Olsen grade II–III AK treated in routine clinical practice with either a bland emollient lead-in followed by tirbanibulin (Group A) or salicylic acid 30% ointment pre-treatment (Decapan, Sanitpharma; Milan, Italy) followed by tirbanibulin (Group B). No study-driven procedures or additional visits were implemented. The 14-day bland emollient lead-in used in Group A was part of the routine clinical management applied during the relevant treatment period and was not introduced or retrospectively constructed for the purposes of the present comparative analysis. Outcomes were extracted from de-identified medical records and photographic documentation obtained as part of standard care. For the purposes of analysis, post-treatment evaluations were grouped into predefined windows of 3–6 weeks (T1), 10–14 weeks (T2), and 22–30 weeks (T3), corresponding approximately to 1, 3, and 6 months after treatment initiation. The primary efficacy endpoints were the Actinic Keratosis Area and Severity Index (AKASI) and Total Lesion Count (TLC). Secondary endpoints included quality of life assessed by the Dermatology Life Quality Index (DLQI). Results: Both treatment regimens were associated with clinically meaningful improvements in AK severity. At T3, mean AKASI was significantly lower in Group B than in Group A (0.86 ± 0.38 vs. 1.35 ± 0.27; p < 0.001), corresponding to reductions from baseline of 60.6% and 36.9%, respectively. Similarly, mean TLC at T3 was significantly lower in Group B than in Group A (4.80 ± 1.5 vs. 6.35 ± 1.6; p < 0.001), corresponding to reductions from baseline of 46.7% and 27.0%, respectively. Quality-of-life outcomes also favored the sequential approach, with lower DLQI scores at T3 in Group B compared with Group A (2.9 ± 1.6 vs. 3.8 ± 1.9; p = 0.006). Both treatments were generally well tolerated. Although the incidence of local skin reactions (LSRs) was similar between groups, Group B showed lower retrospectively documented composite LSR scores and lower patient-reported discomfort (p < 0.001) and lower patient-reported discomfort (p < 0.001). Conclusions: Sequential keratolytic pretreatment followed by tirbanibulin was associated with greater reductions in disease burden and with lower severity of treatment-related local reactions in this retrospective cohort (Olsen grade II–III). This retrospective study suggests that keratolytic pretreatment may represent a useful adjunctive strategy in hyperkeratotic AK treated with tirbanibulin. Prospective randomized studies are warranted to confirm these findings and to define standardized treatment protocols. Full article

Cutaneous squamous cell carcinoma (cSCC) is one of the most common non-melanoma skin cancers worldwide. Although surgery and adjuvant therapies are often effective, the treatment of high-risk or advanced lesions remains challenging due to recurrence, resistance, toxicity, and limited long-term control. Natural compounds have, therefore, gained interest as multi-target agents for cancer prevention and treatment. This systematic review aimed to evaluate the antitumoral activity of natural compounds against cSCC. A systematic literature search was conducted following PRISMA 2020 guidelines. Sixty studies met the inclusion criteria and were analyzed using a conservative, mechanism-based classification framework. The included studies evaluated purified compounds, crude extracts, essential oils, formulations, and combination treatments. Despite chemical diversity, antitumoral activity converged on defined biological processes, including apoptosis, non-apoptotic regulated cell death, redox modulation, oncogenic signaling inhibition, cell-cycle arrest, epigenetic regulation, photodynamic ROS generation, and chemopreventive or immune-mediated mechanisms. Mechanistic specificity was higher among purified compounds, while complex extracts showed broader, context-dependent effects. Several agents demonstrated consistent in vitro and in vivo activity, which supports their translational relevance. Natural compounds target shared biological vulnerabilities in cSCC through mechanistically convergent pathways. The framework presented here supports mechanism-guided prioritization and may facilitate the translation of promising compounds into clinically relevant strategies. Full article

Mohs micrographic surgery (MMS) is a highly specialized skin cancer procedure that combines complete microscopic margin assessment with maximal preservation of uninvolved tissue. The technique is based on staged excision of the tumor with systematic horizontal sectioning and real-time examination of the entire peripheral and deep surgical margins, allowing further tissue removal only in areas where residual tumor is identified. Its unique strength lies in the ability to detect subclinical tumor extensions that may be missed by conventional excision and standard vertical sectioning, thereby improving local control while minimizing unnecessary tissue sacrifice. Since its introduction in the 1930s by Frederic E. Mohs, the technique has evolved into a cornerstone of modern dermato-oncology, particularly for tumors arising in anatomically critical areas, recurrent neoplasms, and histologically aggressive malignancies. MMS is now widely regarded as the treatment of choice for high-risk basal cell carcinoma and cutaneous squamous cell carcinoma because of its superior cure rates and tissue-sparing approach. Beyond its oncologic advantages, MMS allows precise clinicopathologic correlation and immediate reconstruction tailored to the final defect, contributing to favorable functional and cosmetic outcomes. As experience with the technique has expanded, so too has interest in adjunctive tools for preoperative tumor delineation and margin control, further refining patient selection and surgical accuracy. Overall, MMS represents an essential advance over conventional excision for selected cutaneous malignancies, offering an optimal balance between radical tumor clearance and preservation of normal tissue. Full article

Background: Actinic keratoses are common keratinocytic precursor lesions arising within chronically ultraviolet-damaged skin and are associated with an increased risk of progression to cutaneous squamous cell carcinoma. The concept of field cancerization has shifted therapeutic strategies from the treatment of isolated visible lesions toward broader field-directed approaches targeting both clinical and subclinical disease. Methods: This narrative review summarizes the rationale, mechanisms of action, efficacy profile, tolerability, and practical limitations of currently available field-directed therapies for actinic keratosis, including 5-fluorouracil, imiquimod, diclofenac, photodynamic therapy, and tirbanibulin. Based on their distinct biological targets, we propose a mechanism-based framework for sequential treatment strategies. Results: Available therapies act through partially non-overlapping mechanisms, including cytotoxic activity, immune activation, cyclooxygenase-2 inhibition, photodynamic oxidative damage, and tubulin/Src pathway inhibition. These complementary effects provide a biological rationale for sequential regimens aimed at addressing the heterogeneity of field cancerization. However, direct clinical evidence supporting specific treatment sequences remains limited, and proposed regimens should be interpreted as hypothesis-generating rather than as validated therapeutic protocols. Conclusions: Mechanism-based sequential field therapy may represent a rational strategy to optimize long-term control of actinic keratosis and field cancerization. Prospective comparative studies are needed to define optimal sequences, treatment intervals, patient selection criteria, and clinically meaningful endpoints, including sustained field clearance, recurrence reduction, tolerability, adherence, and prevention of progression to invasive cutaneous squamous cell carcinoma. Full article

Nicotinamide (NAM), the amide form of vitamin B3, has gained increasing attention in dermatology due to its potential role in both skin aging and non-melanoma skin cancer (NMSC) prevention. This review summarizes the biological rationale and current clinical evidence supporting the use of NAM and other NAD⁺ precursors in photoaging and cutaneous carcinogenesis. Chronic ultraviolet exposure induces DNA damage, oxidative stress, inflammation, immune dysregulation, and extracellular matrix remodeling, linking photoaged skin to increased susceptibility to actinic keratoses (AKs), squamous cell carcinoma (SCCs), and basal cell carcinoma (BCCs). Through the NAD⁺ salvage pathway, NAM contributes to the maintenance of intracellular NAD⁺ pools, thereby influencing energy metabolism, DNA repair, mitochondrial function, redox homeostasis, and the activity of NAD⁺-dependent enzymes. Preclinical studies indicate that NAM enhances DNA repair, reduces oxidative stress and inflammatory signaling, supports autophagy and mitophagy, and improves epidermal barrier function and extracellular matrix integrity. Clinically, the strongest evidence for anti-aging effects concerns topical NAM, which consistently improves wrinkles, texture irregularities, pigmentation, and barrier function. Oral NAM has demonstrated chemopreventive activity in high-risk patients with previous NMSC, particularly by reducing the incidence of new SCCs and AKs during active treatment. However, despite a strong mechanistic rationale, current evidence remains heterogeneous, and additional long-term, skin-focused clinical trials are needed to better define efficacy, safety, optimal dosing strategies, and patient selection. Full article

Cutaneous squamous cell carcinoma (cSCC) is a common malignant skin tumor with invasive potential and risk of recurrence. This study investigated the anti-cSCC effects of luteolin in vitro and in vivo and explored the associated molecular mechanisms. The effects of luteolin on A431 cell viability were assessed by CCK-8 assay, and apoptosis was analyzed by Annexin V-FITC/propidium iodide (PI) double staining. qRT-PCR and Western blot analyses were performed to evaluate apoptosis-related factors and the EGFR/PI3K/AKT signaling pathway. Molecular docking was further conducted to explore the potential interactions of luteolin with EGFR/PI3K/AKT signaling-related proteins and apoptosis-associated proteins. In vivo, a two-stage skin carcinogenesis model induced by 7,12-dimethylbenz[a]anthracene (DMBA) and croton oil was used to evaluate the antitumor activity of luteolin. Luteolin significantly inhibited A431 cell viability and promoted apoptosis in a concentration-dependent manner. Moreover, luteolin increased Bax expression and decreased Bcl-2 expression at both the mRNA and protein levels. Mechanistically, luteolin suppressed the phosphorylation of EGFR, PI3K, and AKT. Molecular docking suggested that luteolin could interact with EGFR, PIK3CA, AKT, Bax, and Bcl-2, providing supportive in silico evidence for its potential modulation of EGFR/PI3K/AKT signaling and apoptosis-related proteins. In vivo, luteolin alleviated body weight loss, achieved a tumor nodule inhibition rate of 45.28%, significantly improved spleen and thymus indices (p < 0.05), and ameliorated histopathological damage in skin tissues. In addition, immunohistochemical analysis showed that luteolin reduced Ki-67 expression. These results indicate that luteolin exerts anti-cSCC effects in vitro and in vivo, possibly through modulation of the EGFR/PI3K/AKT signaling pathway and apoptosis-related proteins. Full article

Background/Objectives: Cutaneous squamous cell carcinoma (cSCC) develops through inflammation-driven preneoplastic alterations characterized by epidermal hyperplasia, dysplasia, and increased proliferative activity. C-phycocyanin (C-PC) possesses antioxidant and anti-inflammatory properties; however, its topical potential to attenuate a tumour-promoting cutaneous microenvironment is limited by poor skin penetration. This study evaluated the effects of C-PC-loaded transfersomes in a 7,12-dimethylbenz[a]anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse model of skin carcinogenesis. Methods: Male BALB/c mice were assigned to six groups (n = 10 per group). Carcinogenesis was initiated with a single topical application of DMBA, followed by twice-weekly TPA application for 16 weeks. C-PC-loaded transfersomes (1 mg/mL or 10 mg/mL) were applied topically. Histopathological assessment included epidermal thickness, rete ridge depth, mitotic activity, mast cell density, and semi-quantitative scoring of hyperplasia, dysplasia, and inflammation. Ki-67 immunohistochemistry was used to evaluate basal and suprabasal proliferation. Results: Carcinogen exposure induced marked epidermal thickening, severe dysplasia, increased mitotic activity, elevated Ki-67 expression, and pronounced dermal inflammation. Treatment with C-PC-loaded transfersomes significantly reduced epidermal thickness, rete ridge depth, mast cell density, mitotic counts, and suprabasal Ki-67 index. The 1 mg/mL concentration demonstrated the most consistent attenuation of dysplasia severity and inflammatory changes. No adverse histopathological alterations were observed in internal organs. Conclusions: These findings indicate that transfersome-mediated topical delivery of C-PC attenuates early inflammation-driven epidermal remodelling and tumour-promoting alterations in experimental skin carcinogenesis, supporting its potential as a topical preventive strategy. Full article

Fanconi anemia (FA) is a rare inherited disorder associated with impaired DNA repair, characterized by congenital anomalies, bone marrow failure, and a significantly increased risk of developing malignancies, particularly squamous cell carcinoma (SCC) of the head and neck. Treatment options for advanced SCC in FA are limited due to hypersensitivity to DNA-damaging agents. This article presents a unique case of SCC that developed in a 17-year-old patient with FA caused by a homozygous mutation in the FANCA gene. At the age of 10, he received a bone marrow transplant from a compatible related donor. Conditioning therapy included busulfan, thymoglobulin, and fludarabine, while graft-versus-host disease (GvHD) prophylaxis was administered with rituximab, methotrexate, and cyclosporine A. Nevertheless, he developed chronic cutaneous GVHD, which was treated for four years with ruxolitinib and tacrolimus, achieving only partial control. During this period, locally advanced cutaneous SCC (T3N0M0, stage III) manifested on the face. Surgery, radiation therapy, and immunotherapy with pembrolizumab led only to an initial partial response. This first pediatric case of immunotherapy for SCC in FA highlights the challenges of treating this rare patient group. Nevertheless, combining radiation therapy with immunotherapy may represent a possible option for disease control. Full article

Mice lacking epidermal Pparg (Pparg-/-^epi) exhibit increased cutaneous carcinogenesis, while PPARγ signaling is reduced in actinic keratoses (AKs) and cutaneous squamous cell carcinomas (cSCCs). Using transcriptomic analysis, we now show that the top upregulated genes in Pparg-/-^epi mouse skin, human AKs and cSCCs encode multiple damage-associated molecular patterns (DAMPs) that are TLR4 ligands, while the TLR4 agonist lipopolysaccharide (LPS) is also predicted to be the top common activated upstream regulator in both Pparg-/-^epi mouse skin and in tumor datasets. By single-cell sequencing, DAMP expression was particularly elevated in myeloid cells and myofibroblasts of Pparg-/-^epi mice, and these cell types exhibit transcriptional changes consistent with TLR4 signaling. Myeloid cells also exhibited a loss of Pparg expression and activity. Transcriptional analysis of published LPS-treated macrophages also reveals a decrease in PPARγ activity. Fibroblasts from Pparg-/-^epi mice included cells with a gene expression profile resembling myofibroblasts found in cancer and fibrotic diseases. This was accompanied by increased dermal fibrosis in aged mice and a transcriptomic profile that indicates a key role for both TLR4 and TGFβ signaling. These data suggest that loss of epidermal PPARγ may disrupt counterbalancing PPARγ–TLR4 signals, leading to chronic inflammation and fibrosis, hallmarks of cutaneous neoplasia. Full article

Background and Objectives: Invasive cutaneous squamous cell carcinoma (cSCC) and actinic keratosis (AK) are growing burdens on ageing societies and mainly arise from chronic sun exposure. Distinguishing between carcinoma and carcinoma in situ is often clinically challenging but essential for decision-making with respect to targeted therapy. Ex vivo confocal laser scanning microscopy (CLSM) allows histologic examination of native tissue using tissue reflection and nuclear fluorescence staining. The digital staining process almost perfectly mimics conventional haematoxylin and eosin (HE) staining. While the use of CLSM for basal cell carcinoma (BCC) diagnosis is well described, data on cSCC remain scarce. The aim of this study was to compare CLSM with conventional histology in diagnosing and distinguishing cSCC and AK in routine clinical practice. Materials and Methods: Between August 2022 and March 2024, 63 patients with clinically suspected invasive cSCC or AK were enrolled. Biopsy or excision specimens were examined by ex vivo confocal laser scanning microscopy (VivaScope^® 2500 M-G4) followed by acridine orange staining. All samples underwent subsequent routine histopathology, which served as the reference. Two dermatologists independently compared the CLSM findings with the histopathological diagnoses. Results: Eighty-one lesions suspected to be cSCC were assessed using CLSM. The diagnostic accuracy was high across specimen types: cSCC was correctly identified in 24/26 cases (92.3%), AK/Morbus Bowen in 16/17 cases (94.1%), cSCC filia (cutaneous squamous cell carcinoma metastases) in 3/3 cases (100%), and basal cell carcinoma in 9/9 cases (100%). The absence of a tumour was correctly recognized in 19/21 cases (90.5%). In five cases (6.2%), AK and early invasive cSCC could not be differentiated, reflecting the histopathological results. Conclusions: CLSM with digital HE staining is well suited for rapid cSCC and AK diagnosis and differentiation in clinical practice. Full article

Background and Objectives: Sentinel lymph node biopsy (SLNB) is increasingly used for high-risk, clinically node-negative cutaneous squamous cell carcinoma (cSCC), yet pathological reporting remains binary, lacking morphological stratification. The prognostic relevance of nodal tumor burden subtypes—isolated tumor cells (ITC), micrometastases, and macrometastases—is well established in melanoma and breast cancer but remains uncharacterized in cSCC. We aimed to describe the morphological spectrum of sentinel lymph node involvement in a consecutive institutional cohort and determine whether primary tumor characteristics predict the extent of nodal colonization. Materials and Methods: We conducted a retrospective-observational study at Clinical Center Niš (Serbia) including 35 consecutive clinically N0 high-risk cSCC patients who underwent SLNB using a dual-tracer protocol (⁹⁹mTc-labeled albumin and methylene blue). Sentinel nodes were processed by serial sectioning with hematoxylin-eosin and pancytokeratin (AE1/AE3) immunohistochemistry. Deposits were classified as ITC (≤0.2 mm), micrometastases (>0.2–2.0 mm), or macrometastases (>2.0 mm). Clinicopathologic predictors were evaluated using the Mann–Whitney U test, Fisher’s exact test, the Kruskal–Wallis test, and the Spearman rank correlation test. Results: SLN involvement was identified in 12 of 35 patients (34.3%). Among positive cases, ITC accounted for 6 patients (50.0%), micrometastases for 5 (41.7%), and macrometastasis for 1 (8.3%)—minimal nodal disease constituting 91.7% of positive findings. No primary tumor feature—including diameter, thickness, grade, perineural invasion, or lesion multiplicity—significantly distinguished ITC from overt metastatic deposits. Patients with ITC showed numerically higher median tumor thickness (8.0 mm) than those with micrometastases (4.0 mm), though this did not reach significance (Kruskal–Wallis p = 0.065). Conclusions: SLN positivity in high-risk cSCC is morphologically heterogeneous, with minimal nodal disease predominating. Primary tumor features do not reliably stratify the extent of nodal colonization. Structured tumor-burden reporting—distinguishing ITC, micrometastases, and macrometastases—should be adopted as standard practice to enable meaningful prognostic comparisons and inform individualized management. Full article

Background: Terahertz (THz) waves exhibit both photon-like and electron-like properties, showing emerging potential in biomedical applications. Cutaneous squamous cell carcinoma (CSCC) is one of the most common skin tumors. Studies have reported that THz waves can induce apoptosis in cancer cells or ablate tumor tissues. Our previous studies also confirmed that 0.1 THz radiation could significantly promote apoptosis in cutaneous melanoma cells, while it had no apparent effect on fibroblast viability, proliferation, migration, and apoptosis. However, the effects of 0.1 THz radiation on CSCC cells have not yet been explored. Furthermore, there remains a lack of investigation into the structural and functional effects on fibroblasts. Therefore, it is necessary to conduct a systematic study to evaluate the influence of 0.1 THz radiation on both CSCC cells and fibroblasts in order to better understand its potential therapeutic applications in the treatment of skin cancer. Purpose: This study aims to explore the biological effects of 0.1 THz radiation on SCC-7 cells and to uncover the molecular mechanisms underlying THz-induced apoptosis, as well as its potential effect on L-929 cells. Methods: Cell viability was evaluated through the CCK-8 assay, while cell cycle distribution was analyzed with the DNA content detection kit. Wound healing assays were performed to assess cell migration, and Annexin V-FITC staining was used to detect apoptosis. Caspase-3 activity was measured using the caspase-3 activity assay kit. Cell morphology was observed using the Atomic Force Microscope (AFM) and the Transmission Electron Microscopy (TEM). Alterations in membrane potential were detected with the M09 membrane potential probe kit, and intracellular Ca²⁺ levels were quantified using the Fluo-8 AM fluorescent probe. Mitochondrial permeability transition pore (mPTP) opening was assessed with the MPTP detection kit, mitochondrial membrane potential changes were measured using the JC-1 probe kit, and cellular ATP levels were measured with the enhanced ATP assay kit. Subsequently, proteomic analysis was performed. Intracellular reactive oxygen species (ROS) levels were quantified with the ROS detection kit, and cytochrome c (Cyt c) release was quantified using the mouse Cyt c ELISA kit. Apoptosis-inducing factor (AIF) expression was analyzed at both mRNA and protein levels by quantitative real-time PCR (qPCR) and Western blot. AIF expression in CSCC tissues was further evaluated based on the GSE42677 and GSE45164 databases. Finally, cyclosporin A (CsA) was used to inhibit mPTP, and in combination with the iMAC inhibitor, the Aifm1 expression and Cyt c release were examined. Results: Our results showed that THz waves significantly disrupted the membrane integrity of SCC-7 cells and induced mitochondrial structural and functional damage. This resulted in a significant increase in ROS levels and the activation of mPTP and the mitochondrial apoptosis channel (MAC). THz radiation promoted the release of Cyt c and AIF from mitochondria, triggering a noncanonical caspase-3-dependent apoptosis pathway. Notably, L-929 cells did not show significant phenotypic or apoptotic changes under the same irradiation conditions. Bioinformatics analysis of the Gene Expression Omnibus (GEO) database revealed that AIF expression was significantly altered in CSCC tissues compared to normal skin tissues. Conclusions: These findings indicated that 0.1 THz radiation effectively induced apoptosis in SCC-7 cells by triggering mitochondrial dysfunction and ROS generation, which led to the release of AIF. Furthermore, the dysregulation of AIF in CSCC tissues suggested its potential as a promising biomarker. These results provided important molecular insights into the therapeutic potential of THz radiation, particularly for the treatment of cutaneous squamous cell carcinoma. Full article