The role of surgery in the treatment of malignant melanoma

Surgical interventions have important role in the treatment of all stages of malignant melanoma. Surgery is the primary treatment of localized cutaneous melanoma. Excision of the primary tumor makes it possible to set up the histological diagnosis and to determine pathological prognostic factors. Appropriate surgical margin is important for local disease control. Sentinel lymph node biopsy with detailed histological examination has gained prominent importance for correct histological staging and for determining adjuvant oncological treatment. Surgery is the primary treatment of isolated regional metastases. Surgical methods also have a role in the palliative management of distant metastatic melanoma. In the present review the most important issues of the surgical treatment of malignant melanoma have been discussed in detail.     

Hypertonicity primes malignant melanoma cells for apoptosis

The tumor environment critically influences responsiveness of cancer cells to chemotherapies, most of which activate the mitochondria-regulated (intrinsic) apoptotic cascade to kill malignant cells. Especially skin tumors encounter an environment with remarkable biophysical properties. Cutaneous accumulation of Na⁺ locally establishes osmotic pressure gradients in vivo (hypertonicity or hyperosmotic stress), but whether cutaneous hypertonicity is a factor that modulates the responsiveness of skin cancers to therapeutic apoptosis-induction has thus far not been investigated. Here, we show that hyperosmotic stress lowers the threshold for apoptosis induction in malignant melanoma, the deadliest form of skin cancer. Hypertonic conditions enforce addiction to BCL-2-like proteins to prevent initiation of the mitochondria-regulated (intrinsic) apoptotic pathway. Essentially, hyperosmotic stress primes mitochondria for death. Our work identifies osmotic pressure in the tumor microenvironment as a cell extrinsic factor that modulates responsiveness of malignant melanoma cells to therapy.     

The role of bronchial epithelial cell apoptosis in the pathogenesis of COPD

There is an increased airway inflammation in the pathogenesis of chronic obstructive pulmonary disease (COPD), and it has been suggested that there may also be problem in the apoptosis and renewal of cells. However, there are limited human airway cell studies, in particular those from larger airways such as bronchi. We cultured primary human bronchial epithelial cells (HBECs) from bronchial explants of smokers (n = 6) without COPD and smokers with COPD (n = 8). Apoptosis was studied by fluorescence activated cell sorting. qRT-PCR was used to assess mRNA expression for proteins involving apoptosis including p21^CIP1/WAF1, p53, caspase-8 and caspase-9. Although there was no difference in the rate of viable cells between cells from smokers and COPDs, the level of early apoptotic cells was significantly increased in COPD cells [mean ± standard error of mean (SEM) = 4.86 ± 3.2 %, p = 0.015] as compared to smokers (mean ± SEM = 2.71 ± 1.62 %). In contrast, the rate of late apoptotic cells was significantly decreased in COPD cells (mean ± SEM = 9.82 ± 5.71 %) comparing to smokers (mean ± SEM = 15.21 ± 5.08 %, p = 0.003). Although expression of mRNA for p21^CIP1/WAF1 and caspase-9 was similar in both groups, p53 and caspase-8 mRNA expression was significantly greater in COPD cells. These findings suggest that HBEC apoptosis is increased in COPD, and that this involves p53 and caspase-8 pathways.     

Molecular pathogenesis of malignant melanoma: a different perspective from the studies of melanocytic nevus and acral melanoma

The Clark model for melanoma progression emphasizes a series of histopathological changes beginning from benign melanocytic nevus to melanoma via dysplastic nevus. Several models of the genetic basis of melanoma development and progression are based on this Clark’s multi-step model, and predict that the acquisition of a BRAF mutation can be a founder event in melanocytic neoplasia. However, our recent investigations have challenged this view, showing the polyclonality of BRAF mutations in melanocytic nevi. Furthermore, it is suggested that many melanomas, including acral and mucosal melanomas, arise de novo, not from melanocytic nevus. While mutations of the BRAF gene are frequent in melanomas on non-chronic sun damaged skin which are prevalent in Caucasians, acral and mucosal melanomas harbor mutations of the KIT gene as well as the amplifications of cyclin D1 or cyclin-dependent kinase 4 gene. Amplifications of the cyclin D1 gene are detected in normal-looking ‘field melanocytes’, which represent a latent progression phase of acral melanoma that precedes the stage of atypical melanocyte proliferation in the epidermis. Based on these observations, we propose an alternative genetic progression model for melanoma.     

Unraveling the role of microRNA/isomiR network in multiple primary melanoma pathogenesis

Malignant cutaneous melanoma (CM) is a potentially lethal form of skin cancer whose worldwide incidence has been constantly increasing over the past decades. During their lifetime, about 8% of CM patients will develop multiple primary melanomas (MPMs), usually at a young age and within 3 years from the first tumor/diagnosis. With the aim of improving our knowledge on MPM biology and pathogenesis, we explored the miRNome of 24 single and multiple primary melanomas, including multiple tumors from the same patient, using a small RNA-sequencing approach. From a supervised analysis, 22 miRNAs were differentially expressed in MPM compared to single CM, including key miRNAs involved in epithelial–mesenchymal transition. The first and second melanoma from the same patient presented a different miRNA profile. Ten miRNAs, including miR-25-3p, 149-5p, 92b-3p, 211-5p, 125a-5p, 125b-5p, 205-5p, 200b-3p, 21-5p, and 146a-5p, were further validated in 47 single and multiple melanoma samples. Pathway enrichment analysis of miRNA target genes revealed a more differentiated and less invasive status of MPMs compared to CMs. Bioinformatic analyses at the miRNA isoform (isomiR) level detected a panel of highly expressed isomiRs belonging to miRNA families implicated in human tumorigenesis, including miR-200, miR-30, and miR-10 family. Moreover, we identified hsa-miR-125a-5p|0|−2 isoform as tenfold over-represented in melanoma than the canonical form and differentially expressed in MPMs arising in the same patient. Target prediction analysis revealed that the miRNA shortening could change the pattern of target gene regulation, specifically in genes implicated in cell adhesion and neuronal differentiation. Overall, we provided a putative and comprehensive characterization of the miRNA/isomiR regulatory network of MPMs, highlighting mechanisms of tumor development and molecular features differentiating this subtype from single melanomas.Subject terms: Small RNAs, Melanoma     

Immunity to the melanoma inhibitor of apoptosis protein (ML-IAP; livin) in patients with malignant melanoma

Therapeutic targeting of melanoma antigens frequently focuses on the melanocyte differentiation or cancer-testis families. Antigen-loss variants can often result, as these antigens are not critical for tumor cell survival. Exploration of functionally relevant targets has been limited. The melanoma inhibitor of apoptosis protein (ML-IAP; livin) is overexpressed in melanoma, contributing to disease progression and treatment resistance. Improved understanding of the significance of ML-IAP immune responses in patients has possible therapeutic applications. We found ML-IAP frequently expressed in melanoma metastases by immunohistochemistry. To assess spontaneous immunity to ML-IAP, an overlapping peptide library representing full-length protein was utilized to screen cellular responses in stage I–IV patients and healthy controls by ELISPOT. A broad array of CD4⁺ and CD8⁺ cellular responses against ML-IAP was observed with novel class I and class II epitopes identified. Specific HLA-A*0201 epitopes were analyzed further for frequency of reactivity. The generation of specific CD4⁺ and cytotoxic T cells revealed potent functional capability including cytokine responsiveness to melanoma cell lines and tumor cell killing. In addition, recombinant ML-IAP protein used in an ELISA demonstrated high titer antibody responses in a subset of patients. Several melanoma patients who received CTLA-4 blockade with ipilimumab developed augmented humoral immune responses to ML-IAP as a function of treatment which was associated with beneficial clinical outcomes. High frequency immune responses in melanoma patients, associations with favorable treatment outcomes, and its essential role in melanoma pathogenesis support the development of ML-IAP as a disease marker and therapeutic target.     

Streptococcus pneumoniae: the role of apoptosis in host defense and pathogenesis

Programmed cell death or apoptosis is a recognised feature of infection with Streptococcus pneumoniae, and is observed during pneumococcal meningitis and pneumonia. The cholesterol-dependent cytolysin, pneumolysin, is a major trigger of apoptosis in the brain in association with pneumococcal production of hydrogen peroxide. Pneumococcal cell wall is also an important stimulus for apoptosis. Microbial factors and host factors combine in causing apoptosis in the brain, with hippocampal neurons being particularly susceptible. In pulmonary infection epithelial cell apoptosis contributes to tissue injury but macrophage apoptosis may benefit the host, aiding microbial killing and downregulating the inflammatory response. During sepsis lymphocyte apoptosis may be harmful to the host while dendritic cell apoptosis may limit the generation of an adaptive immune response during infection. Apoptosis induction may be harmful or potentially beneficial during pneumococcal infection and understanding its function in each setting is essential to allow specific therapeutic intervention.     

New insights on the role of apoptosis and autophagy in HIV pathogenesis

Viruses manipulate host cells to ensure their own survival and, at late stages of the viral life cycle, they kill the infected target cell to ensure their propagation. In addition, some viruses induce a bystander killing, a viral strategy to escape from the host's innate and cognate defense systems. In HIV-infection, the disabling of the immune system is initially due to the preferential depletion by apoptosis of virus-specific CD4⁺ T cells in lymphoid tissues, followed by the destruction of non-infected bystander cells. Both the extrinsic and the intrinsic pathways are activated, and this is the consequence of systemic immune activation. This review presents recent developments showing that the gastrointestinal tract is the major reservoir of infected cells and the site of rapid and profound loss of CD4 T cells, and that microbial translocation from the gastrointestinal tract is the cause of immune activation. Furthermore, apoptosis mechanisms involved in HIV-induced neuropathological disorders are discussed, including the role of syncytia that involve the sequential activation of ATM, p38MAPK and p53. Finally, HIV-associated dementia (HAD) was recently found in monkey models to be linked to inhibition of autophagy in neurons, suggesting that homeostasis of autophagy is a reliable security factor for neurons, and challenging the development of new therapeutics aimed at boosting neuronal autophagy to prevent HAD.     

Genistein enhances the cisplatin-induced inhibition of cell growth and apoptosis in human malignant melanoma cells

Genistein, a naturally occurring isoflavone found chiefly in soybeans, has been reported to be a potent antitumor agent. Genistein is presumed to exert multiple effects related to the inhibition of cancer growth. Metastatic melanoma is a chemotherapy-refractory neoplasm. The present study was designed to explore the possible activity of genistein to inhibit the aberrant proliferation and to induce apoptosis of human malignant melanoma cells in cooperation with cisplatin treatment. Five human melanoma cell lines were utilized for these experiments. Genistein at physiologic concentrations (20 microM) did not induce apoptosis by itself but did enhance cisplatin-induced apoptosis in all five human melanoma cell lines tested. The enhanced susceptibility among the cell lines was diverse. Changes in the expression of two anti-apoptotic proteins, bcl-2 and bcl-xL, and one pro-apoptotic protein, apoptotic protease activating factor-1 (Apaf-1), were examined. Genistein alone or cisplatin alone generally did not alter bcl-2 expression or bcl-xL expression, but slightly increased Apaf-1 in some cell lines. The combined treatment with genistein and cisplatin significantly reduced bcl-2 and bcl-xL protein and increased Apaf-1 protein expression. These data suggest that genistein therapy may enhance the chemosensitivity of melanoma patients.     

Epidermal malignant tumors: pathogenesis, influence of UV light and apoptosis

Basal cell carcinoma and squamous cell carcinoma, collectively termed non-melanoma skin cancers are the most common malignant tumors in humans. Basal cell carcinoma grows slowly and metastatic spread is very rare. Squamous cell carcinoma is characterized by infiltrative, destructive growth and metastasis. Long-term exposure of skin to UV light has a great impact on development of these epidermal malignancies. UV light induces cascade of events like well known DNA damage of keratinocytes as well as still completely undetermined influence on apoptotic process through expression of proapoptotic and antiapoptotic molecules. The major role in development of skin cancer is given to proapoptotic p53 molecule or tumor suppressor gene which mutation due to UV exposure leads to resistance of DNA-damaged cell to apoptosis. Other proapoptotic molecules such as Fas ligand (FasL) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) are strongly expressed in basal cell carcinoma and squamous cell carcinoma that could be explained by the ability of tumor to escape the attack of immune system.     

Inhibition of CaMKII-mediated c-FLIP expression sensitizes malignant melanoma cells to TRAIL-induced apoptosis

TRAIL can induce apoptosis in melanoma cells and thus may offer new hope for melanoma therapy. However, many melanoma cells are resistant to TRAIL. To examine molecular mechanisms in cell resistance, we analyzed TRAIL-induced DISC in TRAIL-sensitive melanoma cells and showed that apoptosis-initiating caspase-8 and caspase-10 were recruited to the DISC where they became activated through autocatalytical cleavage, leading to apoptosis through cleavage of downstream substrates such as caspase-3 and DFF45. In TRAIL-resistant melanoma cells, however, c-FLIP proteins were recruited to the DISC, resulting in the inhibition of caspase-8 and caspase-10 cleavage in the DISC. Both calmodulin-dependent protein kinase II (CaMKII) protein and enzymatic activity were upregulated in resistant cells and CaMKII inhibitor KN-93 downregulated expression of c-FLIP proteins, thus sensitizing resistant cells to TRAIL-induced apoptosis. Transfection of CaMKII cDNA in sensitive melanoma cells resulted in cell resistance to TRAIL, where transfection of CaMKII dominant-negative cDNA in resistant cells restored TRAIL sensitivity in cells. These results indicate that the CaMKII-mediated pathway for c-FLIP upregulation protects melanoma cells from TRAIL-induced apoptosis and targeting this pathway may provide novel therapeutic strategies in treatment of melanomas.     

The role of peptidoglycan in pathogenesis

Bacterial pathogens rely on a variety of virulence factors to establish the colonization of a new niche. Although peptidoglycan and its muropeptide derivatives have been known to possess potent biological properties, until recently the molecular bases were poorly understood. With the identification of the cytosolic surveillance mechanism mediated by the nucleotide-binding oligomerization domain (Nod)1 and Nod2 proteins, which detect unique peptidoglycan-derived muropeptides, these muropeptides should be considered as potential virulence factors. Recent research highlights the role of peptidoglycan in the pathogenesis of different human pathogens such as Streptococcus pneumoniae, Listeria monocytogenes or Helicobacter pylori.     

The role of ferroptosis in melanoma

Melanoma is the deadliest form of skin cancer. Although treatment with targeted therapies and immune checkpoint inhibitors has dramatically improved survival in advanced melanoma, many patients do not benefit from these therapies or relapse after an initial period of response. Thus, future outcomes in these categories of melanoma patients will depend on the identification of novel therapeutic targets and methods to enhance existing targeted therapy and immunotherapy regimens. Ferroptosis is a newly identified form of iron-dependent regulated cell death that is morphologically, biochemically, and genetically distinct from apoptosis, autophagy, pyroptosis, and necroptosis. Dysregulation of ferroptosis has been linked to the development of several forms of cancer. This review examines ferroptosis in the context of melanoma. It presents an overview of ferroptosis biology, summarizes and interprets the current literature, and poses several outstanding questions and areas of future direction.     

The new TNM classification of malignant melanoma

The identification of increasingly powerful prognostic factors has led to sequential modifications of the cutaneous melanoma staging system. The American Joint Committee on Cancer (AJCC) recently proposed major revision of tumor node metastasis (TNM) categories and stage groupings for melanoma. The authors summarize the main characteristics of this new TNM classification of malignant melanoma. The importance of the novel technique - sentinel node biopsy - in the management of malignant melanoma is discussed.     

Pitfalls in the diagnosis of malignant melanoma

The histological appearance of benign melanocytic naevi and malignant melanomas can be variable, causing in a significant number of cases severe differential diagnostic problems. The early, thin (less than 1 mm) melanomas have to be differentiated from naevi containing dominant junctional or lentiginous component or pagetoid melanocytosis and from some epithelial tumours, while in cases of thick lesion the diagnosis of thick melanoma, Spitz naevus, deep penetrating naevus or cellular blue naevus should be considered for example. The morphology of the so-called atypical Spitz naevus and atypical pigmented spindle cell naevus show overlapping with malignant melanoma and sometimes in these cases the biological behaviour cannot be assessed. The variable appearance of malignant melanoma is illustrated by the fact that different superficial soft tissue tumours with epithelioid and/or spindle cells or with pigment can mimic it. The rare balloon cell and signet ring cell melanoma is a mimicker of primary or metastatic carcinoma and the desmoplastic variant is often misdiagnosed as benign mesenchymal lesion. Lymph node metastasis of melanoma, when the primary tumour is not known, may raise the possibility of interdigitating reticulum cell tumour or anaplastic large cell lymphoma.