Distribution and colocalization of markers for proliferation, invasion, motility and neoangiogenesis in benign melanocytic naevi and malignant melanomas

Association between cathepsins and skin cancers: A bidirectional two-sample Mendelian randomization study

BACKGROUND

Several cathepsins have been identified as being involved in the development of cancer. Nevertheless, the connection between cathepsins and skin cancers remained highly elusive.

METHODS

A bidirectional Mendelian randomization (MR) analysis was performed to investigate the causal association between cathepsins and skin malignancies. The genome-wide association studies (GWAS) data for cathepsins, malignant melanoma (MM), and basal cell carcinoma (BCC) were obtained from European research. The primary method employed was inverse variance weighted. In addition, MR-Egger, weighted median, weighted mode, and simple mode were also executed. Sensitivity analysis was performed using Cochran's Q test, MR-Egger, and MR-PRESSO.

RESULTS

From univariable MR (UVMR), cathepsin H, and S were determined to have a causal relationship with BCC. Additionally, cathepsin H was identified as associated with MM. Multivariable MR (MVMR) showed that after correcting for risk factors of skin carcinoma, cathepsin H was detected to be protective against BCC, whereas cathepsin S has been observed as a risk factor for BCC. No substantial pleiotropy and heterogeneity were identified in the sensitivity analysis.

CONCLUSION

This study was the first to establish a direct link between cathepsins and skin malignancies. Cathepsin H and S have the potential to serve as new biomarkers for BCC, offering valuable assistance in the prompt identification, treatment, and prevention of the disease. Nevertheless, additional clinical trials are required to validate our findings.

VEGF/VEGFR axis and its signaling in melanoma: Current knowledge toward therapeutic targeting agents and future perspectives

Melanoma is responsible for most skin cancer-associated deaths globally. The progression of melanoma is influenced by a number of pathogenic processes. Understanding the VEGF/VEGFR axis, which includes VEGF-A, PlGF, VEGF-B, VEGF-C, and VEGF-D and their receptors, VEGFR-1, VEGFR-2, and VEGFR-3, is of great importance in melanoma due to its crucial role in angiogenesis. This axis generates multifactorial and complex cellular signaling, engaging the MAPK/ERK, PI3K/AKT, PKC, PLC-γ, and FAK signaling pathways. Melanoma cell growth and proliferation, migration and metastasis, survival, and acquired resistance to therapy are influenced by this axis. The VEGF/VEGFR axis was extensively examined for their potential as diagnostic/prognostic biomarkers in melanoma patients and results showed that VEGF overexpression can be associated with unfavorable prognosis, higher level of tumor invasion and poor response to therapy. MicroRNAs linking to the VEGF/VEGFR axis were identified and, in this review, divided into two categories according to their functions, some of them promote melanoma angiogenesis (promotive group) and some restrict melanoma angiogenesis (protective group). In addition, the approach of treating melanoma by targeting the VEGF/VEGFR axis has garnered significant interest among researchers. These agents can be divided into two main groups: anti-VEGF and VEGFR inhibitors. These therapeutic options may be a prominent step along with the modern targeting and immune therapies for better coverage of pathological processes leading to melanoma progression and therapy resistance.

Randomized, double-blind, placebo-controlled trial of sulindac in individuals at risk for melanoma: evaluation of potential chemopreventive activity

BACKGROUND

Reduced melanoma risk has been reported with regular use of nonsteroidal anti-inflammatory drugs (NSAIDs). However, the ability of NSAIDs to reach melanocytes in vivo and modulate key biomarkers in preneoplastic lesions such as atypical nevi has not been evaluated.

METHODS

This randomized, double-blind, placebo-controlled trial of sulindac was conducted in individuals with atypical nevi (AN) to determine bioavailability of sulindac and metabolites in nevi and effect on apoptosis and vascular endothelial growth factor A (VEGFA) expression in AN. Fifty subjects with AN ≥ 4 mm in size and 1 benign nevus (BN) were randomized to sulindac (150 mg twice a day) or placebo for 8 weeks. Two AN were randomized for baseline excision, and 2 AN and BN were excised after intervention.

RESULTS

Postintervention sulindac, sulindac sulfone, and sulindac sulfide concentrations were 0.31 ± 0.36, 1.56 ± 1.35, and 2.25 ± 2.24 μg/mL in plasma, and 0.51 ± 1.05, 1.38 ± 2.86, and 0.12 ± 0.12 μg/g in BN, respectively. Sulindac intervention did not significantly change VEGFA expression but did increase expression of the apoptotic marker cleaved caspase-3 in AN (increase of 3 ± 33 in sulindac vs decrease of 25 ± 45 in the placebo arm, P = .0056), although significance was attenuated (P = .1103) after adjusting for baseline expression.

CONCLUSIONS

Eight weeks of sulindac intervention resulted in high concentrations of sulindac sulfone, a proapoptotic metabolite, in BN but did not effectively modulate VEGFA and cleaved caspase-3 expression. Study limitations included limited exposure time to sulindac and the need to optimize a panel of biomarkers for NSAID intervention studies.

Immunohistochemical expression of VEGF, HIF1-a, and PlGF in malignant melanomas and dysplastic nevi

We evaluated the role of vascular endothelial growth factor (VEGF), placental growth factor (PlGF), and hypoxia-inducible factor 1-a (HIF1-a) in melanoma angiogenesis and investigated their expression in dysplastic nevi, as potential melanoma precursors. In addition, we examined a possible correlation of VEGF expression with PlGF and HIF1-a. These factors were detected immunohistochemically in 95 melanomas of all types and stages and in 28 dysplastic nevi. We used 10 intradermal melanocytic nevi as controls. HIF1-a was expressed in 93 out of 95 (97.89%) melanomas and in none of the dysplastic or control nevi. HIF1-a expression was more intense in melanocytes around necrotic areas but did not correlate with melanoma type, the Clark staging or the Breslow thickness. A strong positive association was detected between HIF1-a and VEGF expression in all cases. VEGF was detected in 82 out of 95 (86.31%) melanomas and in 21 out of 28 (75%) dysplastic nevi, whereas it was expressed weakly in neoplastic cells of the controls. Its expression was more intense in melanomas, especially in nodular melanomas of elevated stage and thickness. PIGF was detected in 46 out of 95 (48.42%) melanomas and in none of the nevi. Expression did not correlate with melanoma staging nor thickness; however, it was more intense in superficial spreading melanomas, where a weak positive association between VEGF and PlGF was also detected. There was no association between HIF1-a and PlGF in any melanoma type. Hypoxia, through the expression of HIF1-a, plays a key role in melanoma progression; it activates VEGF secretion, which induces angiogenesis and metastasis. The role of PlGF seems to be limited.

Skin layer-specific Melan-A expression during progression of human cutaneous melanoma: implications for diagnostic applications of the marker

Melan-A is widely used in the diagnostics of human melanoma. The immunogenicity of this glycoprotein makes it a potential target in immunotherapy and several authors have suggested its potential as a prognostic factor. Up to now there has been no clear direct evidence of changes of Melan-A expression during the progression of melanoma. We have performed objective immunohistochemical assessment of the expression of Melan-A in benign naevi and melanomas at different stages of progression. Our results show a complex pattern of changes in the expression of Melan-A in melanomas depending on the location of melanoma cells within individual skin layers. The expression of the antigen during tumour progression significantly decreases for melanoma cells located in the granular/spinous layer (r=-0.94, P=0.02) and increases for the papillary layer (r=0.99, P=0.002) and reticular layer (r=0.89, P=0.04). It should also be emphasized that from the Clark II level of progression the melanomas can be detected with high sensitivity and specificity using a simple cut-off test based on the determination of Melan-A expression in tumour cells located within the papillary layer.

Lumican affects actin cytoskeletal organization in human melanoma A375 cells

AIMS

Lumican, a small leucine-rich proteoglycan (SLRP), has attracted attention as a molecule of the extracellular matrix possibly involved in signalling pathways affecting cancer cell behaviour. The remodelling of the actin cytoskeleton, induced in response to external stimuli, is crucial for cell motility and intracellular signal transduction. The main goal of this study was to examine the effects of recombinant lumican on actin organization, the state of actin polymerization, actin isoform expression, and their sub-cellular distribution in the A375 human melanoma cell line.

MAIN METHODS

Fluorescence and confocal microscopy were used to observe actin cytoskeletal organization and the sub-cellular distribution of cytoplasmic beta- and gamma-actins. The ability of actin to inhibit DNaseI activity was used to quantify actin. Western blotting and real-time PCR were used to determine the expression levels of the actin isoforms.

KEY FINDINGS

A375 cells grown on lumican coatings changed in morphology and presented rearranged actin filament organization: from filaments evenly spread throughout the whole cell body to their condensed sub-membrane localization. In the presence of lumican, both actin isoforms were concentrated under the cellular membrane. A statistically significant increase in the total, filamentous, and monomeric actin pools was observed in A375 cells grown on lumican.

SIGNIFICANCE

Novel biological effects of lumican, an extracellular matrix SLRP, on the actin pool and organization are identified, which may extend our understanding of the mechanism underlying the inhibitory effect of lumican on the migration of melanoma cells.

Cyclooxygenase-2 (COX-2): first immunohistochemical marker distinguishing early cutaneous melanomas from benign melanocytic skin tumours

We have reported recently that changes in expression level of COX-2 are correlated with development and progression of human melanoma. In this study, we investigated whether the COX-2 expression level might be a useful immunohistochemical marker for distinguishing cutaneous melanomas from benign melanocytic lesions. Up to now, immunohistochemical markers have not ensured satisfactory sensitivity and specificity of differential pathologic diagnosis of melanoma. The expression of COX-2 was determined immunohistochemically in formalin-fixed, paraffin-embedded specimens of 33 early Clark I/II melanomas and 58 naevi. Mean COX-2 expression in melanomas was significantly stronger than in naevi (P approximately 10(-13)). A simple diagnostic algorithm using threshold values of the COX-2 expression level allows for differentiation between early melanomas and naevi with high sensitivity (Se) and specificity (Sp) (for Se between 91 and 100%, Sp values change between 96.5 and 51.7%). Areas under the receiver operating characteristic curves were, respectively, 0.97+/-0.02 and 0.86+/-0.04 for the COX-2 expression in central and border regions of the lesions. For all the melanomas (not only the early ones),the respective areas under the ROC curve values were 0.98+/-0.01 and 0.97+/-0.02. In conclusion, COX-2 is the first immunohistochemical marker that allows the distinguishing of early melanomas from benign melanocytic lesions with both high sensitivity and specificity.