Cutaneous Melanoma Cell Research Articles

Melanoma Cells from Different Patients Differ in Their Sensitivity to Alpha Radiation-Mediated Killing, Sensitivity Which Correlates with Cell Nuclei Area and Double Strand Breaks

Background/Objective: In this study, for the first time, we examined and compared the sensitivity of four patient-derived cutaneous melanoma cell lines to alpha radiation in vitro and analyzed it in view of cell nucleus area and the formation of double-strand breaks (DSB). Melanoma cells sensitivity to alpha radiation was compared to photon radiation effects. Furthermore, we compared the sensitivity of the melanoma cells to squamous cell carcinoma. Methods: Human melanoma cell lines YDFR.C, DP.C, M12.C, and M16.C, and the squamous cell carcinoma cell line, CAL 27, were irradiated in vitro using Americium-241 as alpha-particle source. Cells were irradiated with doses of 0 to 2.8 gray (Gy). Cell viability, DNA DSB, and nuclear size were measured. Results: 1. Alpha radiation caused death and proliferation arrest of all four melanoma cell lines, but inter-tumor heterogeneity was observed. 2. The most sensitive cell line (DP.C) had a significantly larger nucleus area (408 µm2) and the highest mean number of DSB per cell (9.61) compared to more resistant cells. 3. The most resistant cell, M16.C, had a much lower nucleus area (236.99 µm2) and DSB per cell (6.9). 4. Alpha radiation was more lethal than photon radiation for all melanoma cells. 5. The SCC cell, CAL 27, was more sensitive to alpha radiation than all melanoma cells but had a similar number of DSB (6.67) and nucleus size (175.49 µm2) as the more resistant cells. 6. The cytotoxic effect of alpha radiation was not affected by proliferation arrest after serum starvation. 7. Killing of cells by alpha radiation was marginally elevated by ATR or topoisomerase 1 inhibition. Conclusions: This study demonstrates that various human melanoma cells can be killed by alpha radiation but exhibit variance in sensitivity to alpha radiation. Alpha radiation applied using the Intra-tumoral Diffusing alpha-emitters Radiation Therapy (Alpha DaRT) methodology may serve as an efficient treatment for human melanoma.

Extraction, Characterization, and antineoplastic effect of Macadamia nut extracts against cutaneous melanoma Cells: A Comprehensive study Focused on SK-MEL-28 cells

Extraction, Characterization, and antineoplastic effect of Macadamia nut extracts against cutaneous melanoma Cells: A Comprehensive study Focused on SK-MEL-28 cells

ELK4 targets CHMP6 to inhibit ferroptosis and enhance malignant properties of skin cutaneous melanoma cells.

Ferroptosis, a key factor in tumor progression, is poorly understood at the molecular level. This study investigates how ELK4 and CHMP6 regulate skin cutaneous melanoma (SKCM) cell proliferation and ferroptosis. Analysis of TCGA data reveals high expression of ELK4 and CHMP6 in SKCM. Overexpression of ELK4 or CHMP6 enhances cell proliferation, invasion, and migration while reducing ROS and Fe2 + levels. It also increases GPX4 and xCT expression and decreases ACSL4 levels in SKCM cells. The opposite effects are observed with ELK4 or CHMP6 knockdown. ELK4 binds to the CHMP6 promoter, promoting CHMP6 transcription. Knockdown of CHMP6 reverses the oncogenic effects of ELK4 overexpression. In conclusion, ELK4 enhances proliferation, invasion, and migration while inhibiting ferroptosis in SKCM cells by upregulating CHMP6 transcription. This study sheds light on the intricate mechanisms involved in SKCM progression and identifies potential therapeutic targets in melanoma treatment.

Rational design of solid lipid-polymer hybrid nanoparticles: An innovative glycoalkaloids-carrier with potential for topical melanoma treatment

Despite the promising potential of Solanum plant glycoalkaloids in combating skin cancer, their clinical trials have been halted due to dose-dependent toxicity and poor water solubility. In this study, we present a rational approach to address these limitations and ensure colloidal stability of the nanoformulation over time by designing solid lipid-polymer hybrid nanoparticles (SLPH). Leveraging the biocompatible and cationic properties of polyaspartamides, we employed a new polyaspartamide derivative (P1) as a raw material for this class of nanostructures. Subsequently, we prepared SLPH through a one-step process involving hot-melt emulsification followed by ultrasonication. The physicochemical properties of the SLPH were thoroughly characterized using dynamic light scattering (DLS), ζ-potential analysis, nanoparticle tracking analysis (NTA), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). The optimized formulation exhibited long-term stability over six months under low temperatures, maintaining a particle size around 200 nm, a polydispersity index (PdI) lower than 0.2, and a ζ-potential between +35–40 mV. Furthermore, we evaluated the cytotoxic effect of the SLPH against human cutaneous melanoma cells (SK-MEL-28) compared to human foreskin fibroblast cells (HFF-1). Encapsulation of glycoalkaloids into the nanoparticles (SLPH-GE) resulted in a two-fold greater selective cytotoxic profile for melanoma cells than glycoalkaloids-free (GE). The nanoparticles disrupted the stratum corneum barrier with a penetration depth of approximately 77 μm. These findings underscore the potential of the developed nanosystem as an effective glycoalkaloid carrier with suitable colloidal and biological properties for further studies in topical treatment strategies for cutaneous melanoma.

M6A- and m5C- modified lncRNAs orchestrate the prognosis in cutaneous melanoma and m6A- modified LINC00893 regulates cutaneous melanoma cell metastasis.

As the most important modifications on the RNA level, N6-methyladenosine (m6A-) and 5-methylcytosine (m5C-) modification could have a direct influence on the RNAs. Long non-coding RNAs (lncRNAs) could also be modified by methylcytosine modification. Compared with mRNAs, the function of lncRNAs could be more potent to some extent in biological processes like tumorigenesis. Until now, rare reports have been done associated with cutaneous melanoma. Herein, we wonder if the m6A- and m5C- modified lncRNAs could influence the immune landscape and prognosis in melanoma, and we also want to find some lncRNAs which could directly affect the malignant behaviors of melanoma. Systematically, we explored the expression pattern of m6A- and m5C- modified lncRNAs in melanoma from datasets including UCSC Xena and NCBI GEO, and the prognostic lncRNAs were selected. Then, according to the expression pattern of lncRNAs, melanoma samples from these datasets were divided into several subtypes. Prognostic model, nomogram survival model, drug sensitivity, GO, and KEGG pathway analysis were performed. Furthermore, among several selected lncRNAs, we identified one lncRNA named LINC00893 and investigated its expression pattern and its biological function in melanoma cell lines. We identified 27 m6A- and m5C- related lncRNAs which were significantly associated with survival, and we made a subtype analysis of melanoma samples based on these 27 lncRNAs. Among the two subtypes, we found differences of immune cells infiltration between these two subtypes. Then, LASSO algorithm was used to screen the optimized lncRNAs combination including ZNF252P-AS1, MIAT, FAM13A-AS1, LINC-PINT, LINC00893, AGAP2-AS1, OIP5-AS1, and SEMA6A-AS1. We also found that there was a significant correlation between the different risk groups predicted based on RS model and the actual prognosis. The nomogram survival model based on independent survival prognostic factors was also constructed. Besides, sensitivity to chemotherapeutic agents, GO and KEGG analysis were performed. In different risk groups, a total of 14 drug molecules with different distributions were obtained, which included AZD6482, AZD7762, AZD8055, camptothecin, dasatinib, erlotinib, gefitinib, gemcitabine, GSK269962A, nilotinib, rapamycin, and sorafenib. A total of 55 significantly related biological processes and 17 KEGG signaling pathways were screened. At last, we noticed that LINC00893 had a relatively lower expression in melanoma tissue and cell lines compared with adjacent tissues and epidermal melanocyte, and down-regulation of LINC00893 could promote the malignant behavior of melanoma cells in A875 and MV3. In these two melanoma cell lines, down-regulation of m6A-related molecules like YTHDF3 and METTL3 could promote the expression of LINC00893. We made an analysis of m6A- and m5C- related lncRNAs in melanoma samples and a prediction of these lncRNAs' role in prognosis, tumor microenvironment, immune infiltration, and clinicopathological features. We also found that LINC00893, which is potentially regulated by m6A modification, could serve as a tumor-suppressor in melanoma and play an inhibitory role in melanoma metastasis.

Role of Pap Smear Cervical Cytology in the Diagnosis of Extrauterine Malignancies: Largest Study of 104 Cases from Tertiary Care Cancer Centre in India

Introduction: Extrauterine malignancies in cervical samples are rarely seen. It is important to differentiate these cells from those of primary uterine malignancies to determine appropriate line of further investigations and management. Literature on these lesions is limited largely restricted to case reports. The aim of the present study was to study the spectrum and cytomorphological features of extrauterine malignancies in cervical Pap smears. Materials and Methods: It is a retrospective and descriptive study conducted in Department of Cytopathology from January 2019 to July 2023. All cases of extrauterine malignancies with available cytology material were included in this study. All cases of primary uterine malignancies, i.e., uterine corpus or cervix confirmed by clinical, radiological, and histopathological examination were excluded. Results: 104 out of 11,674 cytology Pap smears were those of extrauterine malignancy. Diagnosis of extrauterine malignancy was given in 47.1% cases, 30.9% were reported as positive for malignancy without giving the possibility of an extrauterine origin, and 22.0% were reported as atypical glandular cells only. In 56 cases where Pap smear was the first investigation which led to the diagnosis. Most common extrauterine malignancy was adenocarcinoma principally from ovarian, colorectal, and vaginal origin. Other epithelial malignancies noted were urothelial carcinoma and invasive breast carcinoma. Among non-epithelial malignancies, we reported vaginal mucosal melanoma, cutaneous melanoma, acute leukaemia, and anaplastic large cell lymphoma. Conclusion: High index of suspicion, presence of squamous and glandular elements with no atypical features, and occasional clusters of cells with marked atypia and usually no necrosis in the background are helpful cytomorphological clues to raise suspicion for extrauterine malignancy. Correlation with serology, radiology, and immunocytochemistry can help in reaching final diagnosis.

The correlation between the MYBL2/CDCA8 signaling pathway of malignant melanoma

ObjectiveInvestigating the effects of MYB proto-oncogene like 2 (MYBL2)-mediated regulation of Cell division cycle associated 8 (CDCA8) expression on the biological activity of cutaneous malignant melanoma cells. MethodsA375 cells with MYBL2 and CDCA8 overexpression and knockdown were evaluated using migration, invasion, and proliferation assays. Besides, cell apoptosis was quantified by flow cytometry. To investigate the tumorigenic effects of MYBL2 knockdown in vivo, A375 cells with MYBL2 knockdown were injected in BALB/C nude mice. ResultsThe levels of MYBL2 and CDCA8 gene expression were notably elevated in A375 cells in comparison to HaCat cells (P < 0.05). Downregulation of MYBL2 led to a notable reduction in the migratory and invasive capability of A375 cells in vitro (P < 0.001). On the contrary, overexpression of MYBL2 enhanced migration and invasion ability (P < 0.001). There existed a positive correlation between CDCA8 and MYBL2 gene and protein expression levels after overexpression or knockdown of MYBL2 (P < 0.001). In the in vivo tumorigenic study, the MYBL2 knockdown group displayed a substantial decrease in tumor volume (P < 0.01) and exhibited decreased CDCA8 expression in tumors in comparison to the control group. ConclusionWe arrived at such a conclusion that MYBL2 promoted the migration, invasion and proliferation ability of cutaneous malignant melanoma cells by targeted regulation of CDCA8 expression in this study.

INTASYL PH-762: PD-1 intratumoral immunotherapy for cutaneous carcinoma.

TPS9620 Background: Immune checkpoint-targeted antibodies directed at PD-1 or PD-L1 block co-inhibitory receptors expressed by anti-tumor T cells, breaking immune tolerance against tumor cells and generating cancer immunity. Intratumoral (IT) immunotherapy aims to use the tumor as a ‘self-vaccine’. Local immune stimulation may induce robust priming of an anti-tumor immune response and generate abscopal tumor responses, mediated by circulating activated anti-tumor immune cells. Local delivery of immunotherapy minimizes systemic exposure and off-target toxicities and may decrease tumor size and improve surgical morbidity. PH-762 is an INTASYL compound designed to precisely silence PD-1 mRNA. INTASYL is a patented, self-delivering RNAi technology platform designed to impart specific properties to small interfering RNAs. PH-762’s unique structural and chemical modifications ensure an optimized cell and tissue uptake profile with IT administration. In vitro investigations have demonstrated efficient uptake of PH-762 by human T cells, silencing of PD-1 mRNA and subsequent protein reduction. Preclinical studies have shown that IT injections of murine-targeted PH-762 (mPH-762) can silence PD-1 mRNA in T cells within the tumor and increase the secretion of IFN-γ. mPH-762 was well tolerated at the maximum administered dose and treatment with mPH-762 provided robust and statistically significant inhibition of tumor growth. Toxicokinetic studies conducted in marmoset monkeys demonstrated that PH-762, when administered intravenously at doses of up to 147 mg/kg, is well-tolerated. No cytokine-release associated cytokines were detected in the plasma of treated monkeys at this dose. Methods: This open-label Phase 1 clinical study (NCT 06014086) is designed to evaluate the safety and tolerability of neoadjuvant use of IT PH-762 in cutaneous squamous cell carcinoma, melanoma, or Merkel cell carcinoma, to determine the pharmacokinetic profile of PH-762 after IT injection, to observe pathologic and immunologic tumor responses, and to determine the recommended dose for development. Escalating dose concentrations of PH-762 (from 1.14 mg/mL through 22.00 mg/mL) are tested serially in cohorts of 3 patients each. Patients receive IT PH-762 once weekly, 4 times over a 3-week period prior to surgical excision, which occurs 5 weeks after the initial injection. Following excision of the tumor, patients are followed for approximately 11 weeks. Tumor changes are evaluated per iRECIST criteria and pathological response. Immunological response in tumor tissue and blood samples are assessed as secondary endpoints. This clinical study, enrolling patients since November 2023, will establish the basis for continued clinical development of PH-762. Clinical trial information: 06014086.

MIIP downregulates PD-L1 expression through HDAC6 in cutaneous melanoma

PurposeImmune checkpoint inhibitors have improved the objective response rate and survival of melanoma patients. However, there are still many melanoma patients suffering from disease progression due to primary or secondary immune checkpoint inhibitor resistance, as is observed in the failure of anti-PD1/PD-L1 therapy. While the expression of valuable markers, such as TMB, MSI, and PD-L1, could serve as effective predictors of anti-checkpoint inhibitor therapies, tumor cell PD-L1 expression and its regulating mechanism would significantly affect the anti-PD-1 immunotherapy response and efficacy. Therefore, it is urgent to determine the function of PD-1/PD-L1 expression in melanoma and its associated pathways to enhance the efficacy of anti-PD-1 therapies.MethodsA cohort of 133 patients with histologically confirmed melanoma from Tianjin Medical University Cancer Institute & Hospital were included in this study. We performed immunohistochemical staining to detect the expression of Migration and invasion inhibitory protein (MIIP), HDAC6 and PD-L1. Kaplan–Meier and log-rank test were used for survival analysis. As for vitro, Western blot was used in melanoma cell lines to verify the signaling pathway that MIIP regulates PD-L1 expression.ResultsMIIP expression was decreased in melanoma and that the negative expression of MIIP was correlated with worse overall survival. The positive expression of HDAC6, a molecule that is downstream of MIIP, had a positive trend with decreased overall survival. At the same time, the positive expression of PD-L1, a crucial costimulatory molecule, was associated with decreased overall survival. Furthermore, there was a positive association between HDAC6 and PD-L1 protein expression (p < 0.01), and this correlation is more prominent in cutaneous melanoma than acral melanoma. In cutaneous melanoma cell lines, we found that increasing MIIP led to decreased HDAC6, pSTAT3, and PD-L1 expression. Knocking down MIIP led to increased HDAC6, pSTAT3, and PD-L1 expression. Combining the published results, showing that HDAC6 can regulate PD-L1 expression through STAT3, our present data suggest that MIIP inhibits the expression of PD-L1 by downregulating HDAC6 in melanoma. Most importantly, methods for targeting MIIP-HDAC6-PD-L1 pathways, such as treatment with HDAC6 inhibitors, might indicate a new therapeutic approach for enhancing immune checkpoint inhibitor therapies in melanoma.ConclusionsOur findings highlight the immunomodulatory effects of MIIP in the inhibition of PD-L1 expression by downregulating HDAC6 in melanoma. Methods for targeting MIIP-HDAC6-PD-L1 pathways might be new therapeutic approaches for enhancing immune checkpoint inhibitor therapies in melanoma.

Curcumin modulates purinergic signaling and inflammatory response in cutaneous metastatic melanoma cells.

Cutaneous melanoma (CM) poses a therapeutic challenge due to its aggressive nature and often limited response to conventional treatments. Exploring novel therapeutic targets is essential, and natural compounds have emerged as potential candidates. This study aimed to elucidate the impact of curcumin, a natural compound known for its anti-inflammatory, antioxidant, and anti-tumor properties, on metastatic melanoma cells, focusing on the purinergic system and immune responses. Human melanoma cell line SK-Mel-28 were exposed to different curcumin concentrations for either 6 or 24h, after which we assessed components related to the purinergic system and the inflammatory cascade. Using RT-qPCR, we assessed the gene expression of CD39 and CD73 ectonucleotidases, as well as adenosine deaminase (ADA). Curcumin effectively downregulated CD39, CD73, and ADA gene expression. Flow cytometry analysis revealed that curcumin significantly reduced CD39 and CD73 protein expression at specific concentrations. Moreover, the A2A receptor's protein expression decreased across all concentrations. Enzymatic activity assays demonstrated that curcumin modulated CD39, CD73, and ADA activities, with effects dependent on concentration and duration of treatment. Extracellular ATP levels increased after 24h of curcumin treatment, emphasizing its role in modulating hydrolytic activity. Curcumin also displayed anti-inflammatory properties by reducing NLRP3 gene expression and impacting the levels of key inflammatory cytokines. In conclusion, this study unveils the potential of curcumin as a promising adjuvant in CM treatment. Curcumin modulates the expression and activity of crucial components of the purinergic system and exhibits anti-inflammatory effects, indicating its potential therapeutic role in combating CM. These findings underscore curcumin's promise and warrant further investigation in preclinical and clinical settings for melanoma management.

GZ17-6.02 kills PDX isolates of uveal melanoma.

GZ17-6.02 has undergone phase I evaluation in patients with solid tumors (NCT03775525). The RP2D is 375 mg PO BID, with an uveal melanoma patient exhibiting a 15% reduction in tumor mass for 5 months at this dose. Studies in this manuscript have defined the biology of GZ17-6.02 in PDX isolates of uveal melanoma cells. GZ17-6.02 killed uveal melanoma cells through multiple convergent signals including enhanced ATM-AMPK-mTORC1 activity, inactivation of YAP/TAZ and inactivation of eIF2α. GZ17-6.02 significantly enhanced the expression of BAP1, predictive to reduce metastasis, and reduced the levels of ERBB family RTKs, predicted to reduce growth. GZ17-6.02 interacted with doxorubicin or ERBB family inhibitors to significantly enhance tumor cell killing which was associated with greater levels of autophagosome formation and autophagic flux. Knock down of Beclin1, ATG5 or eIF2α were more protective than knock down of ATM, AMPKα, CD95 or FADD, however, over-expression of FLIP-s provided greater protection compared to knock down of CD95 or FADD. Expression of activated forms of mTOR and STAT3 significantly reduced tumor cell killing. GZ17-6.02 reduced the expression of PD-L1 in uveal melanoma cells to a similar extent as observed in cutaneous melanoma cells whereas it was less effective at enhancing the levels of MHCA. The components of GZ17-6.02 were detected in tumors using a syngeneic tumor model. Our data support future testing GZ17-6.02 in uveal melanoma as a single agent, in combination with ERBB family inhibitors, in combination with cytotoxic drugs, or with an anti-PD1 immunotherapy.

Combined therapy of dabrafenib and an anti-HER2 antibody–drug conjugate for advanced BRAF-mutant melanoma

BackgroundMelanoma is the most lethal skin cancer characterized by its high metastatic potential. In the past decade, targeted and immunotherapy have brought revolutionary survival benefits to patients with advanced and metastatic melanoma, but these treatment responses are also heterogeneous and/or do not achieve durable responses. Therefore, novel therapeutic strategies for improving outcomes remain an unmet clinical need. The aim of this study was to evaluate the therapeutic potential and underlying molecular mechanisms of RC48, a novel HER2-target antibody drug conjugate, either alone or in combination with dabrafenib, a V600-mutant BRAF inhibitor, for the treatment of advanced BRAF-mutant cutaneous melanoma.MethodsWe evaluated the therapeutic efficacy of RC48, alone or in combination with dabrafenib, in BRAF-mutant cutaneous melanoma cell lines and cell-derived xenograft (CDX) models. We also conducted signaling pathways analysis and global mRNA sequencing to explore mechanisms underlying the synergistic effect of the combination therapy.ResultsOur results revealed the expression of membrane-localized HER2 in melanoma cells. RC48 effectively targeted and inhibited the growth of HER2-positive human melanoma cell lines and corresponding CDX models. When used RC48 and dabrafenib synergically induced tumor regression together in human BRAF-mutant melanoma cell lines and CDX models. Mechanically, our results demonstrated that the combination therapy induced apoptosis and cell cycle arrest while suppressing cell motility in vitro. Furthermore, global RNA sequencing analysis demonstrated that the combination treatment led to the downregulation of several key signaling pathways, including the PI3K-AKT pathway, MAPK pathway, AMPK pathway, and FOXO pathway.ConclusionThese findings establish a preclinical foundation for the combined use of an anti-HER2 drug conjugate and a BRAF inhibitor in the treatment of BRAF-mutant cutaneous melanoma.

Abstract 568: Modulation of HER4 isoforms expression in estrogen-stimulated in vitro models

Abstract Introduction HER4, a tyrosine kinase receptor belonging to the Human Epidermal Growth Factor/HER/ErbB-family, has a complex biology that includes four isoforms (JMa-CYT1/2, and JMb-CYT1/2) and tissue specific oncogenic or tumour suppressor roles. In estrogen receptor positive (ER+) breast cancer (BC), HER4 isoforms can either act as a co-regulator of ESR1-mediated gene expression by localising to the nucleus, or activate apoptosis by localising to mitochondria. There is very little known about HER4 function in cutaneous melanoma, despite cutaneous melanoma showing the highest HER4 genomic alteration frequency (17.34%) across different cancers (cBioPortal). Due to the interplay between estrogen signalling and HER4 isoforms in ER+BC, this study investigates the RNA expression of HER4 isoforms along with hormone and nuclear receptors associated with 17β-estradiol stimulation in ER+BC and cutaneous melanoma in vitro models. Material and Methods CAMA1 (ER+BC) and SKMEL24 (cutaneous melanoma) cell lines were serum starved for 4h prior to stimulation with 17β-estradiol (0.5nM, 1nM, 5nM and 10nM). RNA was extracted from cells after 24h using TRIzol, followed by qRT-PCR to assess the expression of HER4 isoforms, the hormone receptors estrogen receptor 1 (ESR1/ER-alpha), estrogen receptor 2 (ESR2/ER-beta), progesterone receptor (PGR/PR), G protein-coupled estrogen receptor 1 (GPER1) and the nuclear receptors retinoic acid receptor alpha (RARA) and retinoid X receptor alpha (RXRA). Cell proliferation and caspase3/7 apoptosis analysis were performed at 24/48/72h in the 17β-estradiol stimulated cells by using the IncuCyte Live Cell Analysis Instrument (Sartorius). SN-38 (150nM) was used as positive control for apoptosis induction. Two-way ANOVA was used for the statistical analysis, p&amp;lt;0.05 was significant. Results The qRT-PCR analysis showed that upon stimulation of CAMA1 with 1nM of 17β-estradiol there is a numerical shift in the CYT-1/CYT-2 ratio towards CYT-2 (not statistically significant, p&amp;gt;0.05) and a significant increase in PGR (p= 0.0027) and RAR-A (p= 0.0248) expression compared to control. CAMA1 stimulated with any concentration of 17β-estradiol showed an increase in proliferation compared to the control. The stimulation of SKMEL24 with 5nM of 17β-estradiol showed an increase in JM-a (p=0.0075) and CYT-1 (p=0.0271) HER4 isoforms, GPER1 (p= 0.0286), and a dose-dependent increase in RARA (p=0.0011) compared to control, even in the absence of ESR1, ESR2 and PGR. SKMEL24 stimulated with 17β-estradiol showed a decrease in proliferation compared to control, but no apoptosis induction was found. Conclusion These findings suggest potential interplay between 17β-estradiol and HER4 isoforms leading to the activation of intracellular pathways that could influence tumour progression/suppression in melanoma. Further studies are needed to clarify the specific receptor interactions and pathways involved. Citation Format: Marta Valenti, Georg F. Bischof, John P. Crown, Denis M. Collins. Modulation of HER4 isoforms expression in estrogen-stimulated in vitro models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 568.

Chemical profile and biological properties of the Piper corcovadense C.DC. essential oil

The essential oil fromPiper corcovadense D.DC. (EOPc), an important plant belonging to the Piperaceae family, which is commonly found in the northern region of Brazil and poorly explored scientifically, was used in this study. Thus, the EOPc was characterized chemically by Gas Chromatography/Mass Spectrometry (GC/MS) and the antioxidant and antimicrobial activities and their potential effects on cutaneous melanoma (SK-MEL-28) and healthy peripheral blood mononuclear (PBMC) cells were determined. The major compounds identified in the EOPc were: trans-sesquisabinene hydrate, trans-caryophyllene, β-pinene, trans-β-farnesene, 14-hydroxycaryophyllene, limonene and p-cymene. The EOPc demonstrated antioxidant activity as evaluated by Folin-Ciocalteu reagent (FC) reducing capacity, DPPH, and ABTS methods. The values found were respectively 5.41 ± 0.17 mg GAE mL−1 (GAE: Gallic acid equivalent), 2.88 ± 0.17 µmol TE mL−1 (TE: Trolox equivalent) and 6.26 ± 0.02 µmol TE mL−1. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for different bacterial strains. The EOPc at a concentration of 2.61 µg mL−1 exhibited both bactericidal and bacteriostatic properties against Escherichia coli. The EOPc showed potential antitumor activity as it reduced the cell viability of human cutaneous melanoma cells SK-MEL-28. Besides, the EOPc did not exhibit cytotoxic activity against healthy PBMCs, indicating that it does not harm healthy cells at the tested concentrations. The EOPc increased the levels of ROS at concentrations of 250 µg mL−1. The EOPc also did not stimulate the mobilization of endogenous antioxidant defenses, as assessed by total thiol (PSH) and non-protein thiols (NPSH). Thus, the study suggests that the EOPc has antioxidant and antimicrobial properties due to the presence of specific compounds. It also exhibits antitumor potential against cutaneous melanoma cells while showing no cytotoxicity to healthy PBMCs. It directly influenced ROS levels at the highest tested concentration in the cells, suggesting an antitumor effect related to the intrinsic apoptosis pathway. Nevertheless, while the study has initial findings, the results are promising and indicate an attractive biological potential of P. corcovadense, mainly in human cutaneous melanoma cells.

Cancer Cell Biomechanical Properties Accompany Tspan8-Dependent Cutaneous Melanoma Invasion.

The intrinsic biomechanical properties of cancer cells remain poorly understood. To decipher whether cell stiffness modulation could increase melanoma cells' invasive capacity, we performed both in vitro and in vivo experiments exploring cell stiffness by atomic force microscopy (AFM). We correlated stiffness properties with cell morphology adaptation and the molecular mechanisms underlying epithelial-to-mesenchymal (EMT)-like phenotype switching. We found that melanoma cell stiffness reduction was systematically associated with the acquisition of invasive properties in cutaneous melanoma cell lines, human skin reconstructs, and Medaka fish developing spontaneous MAP-kinase-induced melanomas. We observed a systematic correlation of stiffness modulation with cell morphological changes towards mesenchymal characteristic gains. We accordingly found that inducing melanoma EMT switching by overexpressing the ZEB1 transcription factor, a major regulator of melanoma cell plasticity, was sufficient to decrease cell stiffness and transcriptionally induce tetraspanin-8-mediated dermal invasion. Moreover, ZEB1 expression correlated with Tspan8 expression in patient melanoma lesions. Our data suggest that intrinsic cell stiffness could be a highly relevant marker for human cutaneous melanoma development.

Inhibition of the YAP-MMB interaction and targeting NEK2 as potential therapeutic strategies for YAP-driven cancers.

YAP activation in cancer is linked to poor outcomes, making it an attractive therapeutic target. Previous research focused on blocking the interaction of YAP with TEAD transcription factors. Here, we took a different approach by disrupting YAP's binding to the transcription factor B-MYB using MY-COMP, a fragment of B-MYB containing the YAP binding domain fused to a nuclear localization signal. MY-COMP induced cell cycle defects, nuclear abnormalities, and polyploidization. In an AKT and YAP-driven liver cancer model, MY-COMP significantly reduced liver tumorigenesis, highlighting the importance of the YAP-B-MYB interaction in tumor development. MY-COMP also perturbed the cell cycle progression of YAP-dependent uveal melanoma cells but not of YAP-independent cutaneous melanoma cell lines. It counteracted YAP-dependent expression of MMB-regulated cell cycle genes, explaining the observed effects. We also identified NIMA-related kinase (NEK2) as a downstream target of YAP and B-MYB, promoting YAP-driven transformation by facilitating centrosome clustering and inhibiting multipolar mitosis.

CRABP2 regulates infiltration of cancer-associated fibroblasts and immune response in melanoma.

Finding biomarkers for immunotherapy is an urgent issue in cancer treatment. Cellular retinoic acid-binding protein 2 (CRABP2) is a controversial factor in the occurrence and development of human tumors. However, there is limited research on the relationship between CRABP2 and immunotherapy response. This study found that negative correlations of CRABP2 and immune checkpoint markers (PD-1, PD-L1, and CTLA-4) were observed in breast invasive carcinoma (BRCA), skin cutaneous melanoma (SKCM), stomach adenocarcinoma (STAD) and testicular germ cell tumors (TGCT). In particular, in SKCM patients who were treated with PD-1 inhibitors, high levels of CRABP2 predicted poor prognosis. Additionally, CRABP2 expression was elevated in cancer-associated fibroblasts (CAFs) at the single-cell level. The expression of CRABP2 was positively correlated with markers of CAFs, such as MFAP5, PDPN, ITGA11, PDGFRα/β and THY1 in SKCM. To validate the tumor-promoting effect of CRABP2 in vivo, SKCM xenograft mice models with CRABP2 overexpression have been constructed. These models showed an increase in tumor weight and volume. Enrichment analysis indicated that CRABP2 may be involved in immune-related pathways of SKCM, such as extracellular matrix (ECM) receptor interaction and epithelial-mesenchymal transition (EMT). The study suggests that CRABP2 may regulate immunotherapy in SKCM patients by influencing infiltration of CAFs. In conclusion, this study provides new insights into the role of CRABP2 in immunotherapy response. The findings suggest that CRABP2 may be a promising biomarker for PD-1 inhibitors in SKCM patients. Further research is needed to confirm these findings and to explore the clinical implications of CRABP2 in immunotherapy.

Retraction: Long non-coding RNA FENDRR inhibits migration and invasion of cutaneous malignant melanoma cells.

Retraction: Long non-coding RNA FENDRR inhibits migration and invasion of cutaneous malignant melanoma cells.

Functional assay for assessment of pathogenicity of BAP1 variants.

Pathogenic germline variants in BRCA1-Associated Protein 1 (BAP1) cause BAP1 tumor predisposition syndrome (BAP1-TPDS). Carriers run especially a risk of uveal (UM) and cutaneous melanoma, malignant mesothelioma, and clear cell renal carcinoma. Approximately half of increasingly reported BAP1 variants lack accurate classification. Correct interpretation of pathogenicity can improve prognosis of the patients through tumor screening with better understanding of BAP1-TPDS. We edited five rare BAP1 variants with differing functional characteristics identified from patients with UM in HAP1 cells using CRISPR-Cas9 and assayed their effect on cell adhesion/spreading (at 4h) and proliferation (at 48h), measured as cell index (CI), using xCELLigence real-time analysis system. In BAP1 knockout HAP1 cultures, cell number was half of wild type (WT) cultures at 48h (p = 0.00021), reaching confluence later, and CI was 78% reduced (p < 0.0001). BAP1-TPDS-associated null variants c.67+1G>T and c.1780_1781insT, and a likely pathogenic missense variant c.281A>G reduced adhesion (all p ≤ 0.015) and proliferation by 74%-83% (all p ≤ 0.032). Another likely pathogenic missense variant c.680G>A reduced both by at least 50% (all p ≤ 0.032), whereas cells edited with likely benign one c.1526C>T grew similarly to WT. BAP1 is essential for optimal fitness of HAP1 cells. Pathogenic and likely pathogenic BAP1 variants reduced cell fitness, reflected in adhesion/spreading and proliferation properties. Further, moderate effects were quantifiable. Variant modelling in HAP1 with CRISPR-Cas9 enabled functional analysis of coding and non-coding region variants in an endogenous expression system.

Caffeine reduces viability, induces apoptosis, inhibits migration and modulates the CD39/CD73 axis in metastatic cutaneous melanoma cells.

We aimed to evaluate the effect of caffeine on viability, apoptosis, migration, redox profile and modulatory effect of the purinergic system of cutaneous melanoma cells. The melanoma cells SK-MEL-28 and non-tumoural CCD-1059sk cells were treated for 24 h with different concentrations of caffeine. Cell viability was evaluated by a biochemical assay and fluorescence microscopy, and flow cytometry assessed apoptosis induction. A wound-healing assay assessed cell migration. The redox profile was evaluated by the levels of markers of reactive oxygen species (ROS), nitric oxide (NOx), total thiols (PSH) and non-protein thiols (NPSH). RT-qPCR and flow cytometry assessed the expression of CD39 and CD73. ATPase/ADPase and AMPase enzyme activities were evaluated by hydrolysis of ATP, ADP and AMP nucleotides. A bioluminescent assay assessed extracellular ATP levels. Caffeine significantly reduced melanoma cell viability and migration and did not affect non-tumoural cells. Caffeine increased ROS levels and improved PSH levels in melanoma cells. Furthermore, caffeine reduced CD39 and CD73 expression, decreased ATP, ADP and AMP nucleotide hydrolysis and increased extracellular ATP levels. We have shown that caffeine reduces metastatic cutaneous melanoma cell viability and migration, induces ROS generation and improves PSH levels. In an unprecedented manner, we also showed that caffeine reduces the expression of CD39 and CD73 and, consequently, ATPase/ADPase/AMPase hydrolytic activity of ectonucleotidases, thus displacing the CD39/CD73 axis and increasing extracellular ATP levels. Therefore, caffeine may be an interesting compound for clinical trials with the CD39/CD73 axis as a therapeutic target.