Expression of Melan-A/MART-1 in primary melanoma cell cultures has prognostic implication in metastatic melanoma patients

Targeted cancer treatment using folate-conjugated sponge-like ZIF-8 nanoparticles: a review

ZIF-8 (zeolitic imidazolate framework-8) is a potential drug delivery system because of its unique properties, which include a large surface area, a large pore capacity, a large loading capacity, and outstanding stability under physiological conditions. ZIF-8 nanoparticles may be readily functionalized with targeting ligands for the identification and absorption of particular cancer cells, enhancing the efficacy of chemotherapeutic medicines and reducing adverse effects. ZIF-8 is also pH-responsive, allowing medication release in the acidic milieu of cancer cells. Because of its tunable structure, it can be easily functionalized to design cancer-specific targeted medicines. The delivery of ZIF-8 to cancer cells can be facilitated by folic acid-conjugation. Hence, it can bind to overexpressed folate receptors on the surface of cancer cells, which holds the promise of reducing unwanted deliveries. As a result of its importance in cancer treatment, the folate-conjugated ZIF-8 was the major focus of this review.

Expression of cancer/testis antigens in cutaneous melanoma: a systematic review

The cancer/testis antigen (CTA) family is a group of antigens whose expression is restricted to male germline cells of the testis and various malignancies. This expression pattern makes this group of antigens potential targets for immunotherapy. The aim of this study was to create an overview of CTA expressed by melanoma cells at mRNA and protein level. A systematic literature search was performed in Medline (PubMed) and Embase from inception up to and including February 2018. Studies were screened for eligibility by two independent reviewers. A total of 65 full-text articles were included in the final analysis. A total of 48 CTA have been studied in melanoma. Various CTA show different expression rates in primary and metastatic tumours. Of the 48 CTA, the most studied were MAGE-A3, MAGE-A1, NY-ESO-1, MAGE-A4, SSX2, MAGE-A2, MAGE-C1/CT7, SSX1, MAGE-C2/CT10 and MAGE-A12. On average, MAGE-A3 mRNA is present in 36% of primary tumours, whereas metastatic tumours have an expression rate of 55-81%. The same applies to the protein expression rate of MAGE-A3 in primary tumours, which is reported to be at 15-37%, whereas metastatic tumours have a higher expression rate of 25-70%. This trend of increased expression in metastases compared with primary tumours is observed with MAGE-A1, MAGE-A2, MAGE-A4, MAGE-A12 and NY-ESO-1. Many CTA are expressed on melanoma. This review provides an overview of the expression frequency of CTAs in melanoma and may aid in identifying CTA as the therapeutic target for immunotherapy.

Histologic and immunohistochemical predictors of clinical behavior for feline diffuse iris melanoma

OBJECTIVE

To determine histologic and immunohistochemical predictors of metastasis of feline diffuse iris melanoma (FDIM).

ANIMALS

Globes from 47 client-owned cats enucleated for FDIM between January 1985 and December 2013.

PROCEDURES

Hematoxylin and eosin-stained sections were evaluated for neoplastic invasiveness and cell morphology, necrosis within the neoplasm, inflammation, and glaucoma. Sections were immunolabeled with antibodies against melan-A, PNL2, E-cadherin, or B-Raf, and label intensity, percentage of labeled cells, and label homogeneity were semi-quantitatively graded. Medical records were evaluated, and referring veterinarians and clients were contacted to determine whether cats developed metastasis following enucleation. The log-rank test or Cox proportional hazards model was used to determine associations between histologic or immunohistochemical parameters and metastasis.

RESULTS

Metastasis was suspected or confirmed in 9/47 (19%) cats. Extrascleral extension, necrosis within the neoplasm, a mitotic index of >7 mitoses in 10 high-power (×400) fields, choroidal invasion, and increased E-cadherin and melan-A label intensity were each associated with increased rate of metastasis. PNL2 label homogeneity was associated with decreased rate of metastasis. Decreased PNL2 label intensity and an increasing percentage of neoplastic cells labeled for melan-A each approached significance for increased rate of metastasis.

CONCLUSIONS

We report four histologic and three immunohistochemical parameters helpful in determining cats at risk of metastasis of FDIM. Further studies should determine if B-Raf mutations identified in human malignant melanomas are found in cats with FDIM and assess benefits of adjunctive therapy following enucleation of eyes with FDIM bearing poor prognostic indicators.

MelanA-negative spindle-cell associated melanoma, a distinct inflammatory phenotype correlated with dense infiltration of CD163 macrophages and loss of E-cadherin

MelanA is a known melanocyte marker and is important in melanoma diagnostics. Some tumours, however, show loss of MelanA expression and may therefore be difficult to distinguish from tumours of mesenchymal origin. Pure spindle-cell melanoma is a rare event, and little is known about its biological background and prognosis. However, morphological changes towards a more mesenchymal shape and cellular dedifferentiation may correlate with reactivation of important developmental programmes (epithelial-to-mesenchymal transition) and disseminative tumour cell properties. Inflammation and CD163+ macrophages have been shown to be important inducers of E-cadherin and cell-to-cell adhesion loss, a pivotal and final event of epithelial-to-mesenchymal transition. In a cohort of 385 patients with melanoma, we located nine tumours with a clonal MelanA expression, defined as a tumour section with a distinct MelanA-negative clone next to a MelanA-positive clone. Interestingly, MelanA-negative clones correlated significantly with an augmented inflammatory response of tumour-infiltrating macrophages (CD163+), complete loss of E-cadherin and a spindle-shaped morphology, irrespective of ulcerated status. These cases show the inflammatory heterogeneity of melanoma, which may have important diagnostic, prognostic and therapeutic implications for the patients. We show that melanomas harbour cell clones that bear strong resemblance to tumour-associated macrophages, a pivotal player in a tumour-supporting microenvironment. Interestingly, this distinct inflammatory phenotype is associated with loss of MelanA expression, the presence of spindle-shape morphology and complete loss of E-cadherin, considered as possible markers of poorly differentiated and more invasive tumour cells.

MAGE-A3: an immunogenic target used in clinical practice

Melanoma antigen family A, 3 (MAGE-A3) is a cancer-testis antigen whose expression has been demonstrated in a wide array of malignancies including melanoma, brain, breast, lung and ovarian cancer. In addition, its ability to elicit spontaneous humoral and cellular immune responses has been shown in cancer patients. As antigen-specific immune responses can be stimulated by immunization with MAGE-A3, several clinical trials have used MAGE-A3 vaccines to observe clinical responses. The frequent expressions of this antigen in various tumors and its immunogenicity in cancer patients have led to application of this antigen in cancer immunotherapy. However, the results of recent clinical trials indicate that there is a need for research in the vaccine design, adjuvant selection as well as patient selection criteria.

HER2 as a promising target for cytotoxicity T cells in human melanoma therapy

Anti-HER2/neu antibody therapy has been reported to mediate tumor regression of HER2/ neu(+) tumors. Here we demonstrated the expression of HER2 in a wide range of human melanoma cells including a primary culture and seven cell lines, and we further investigated whether HER2 could be served as a target for T cell mediated immunotherapy of human melanoma. Specific cytolytic activity of activated T cells (ATC) armed with anti-CD3 x anti-HER2 bispecific antibody (HER2Bi-Ab) against Malme-3M-luc cells was evaluated by bioluminescent signal generated by luciferase reporter which did not alter HER2 expression or proliferation ability of Malme-3M cells. Contrast with unarmed ATC, increased cytotoxic activity of HER2Bi-armed ATC against Malme-3M-luc cells was observed at effector/target (E/T) ratios of 1:1, 5:1, and 20:1. Moreover, HER2Bi-armed ATC expressed higher level of activation marker CD69 and secreted significantly higher level of IFN-γ than unarmed ATC counterpart at the E/T ratio of 20:1. In addition, compared with anti-HER2 mAb (Herceptin®) or unarmed ATC, HER2Bi-armed ATC showed remarkable suppression effect on Malme-3M-luc tumor cells. Furthermore, in melanoma tumor cell xenograft mice, infusion of HER2Bi-armed ATC successfully inhibited the growth of melanoma tumors. The anti-tumor effect of HER2Bi-armed ATC may provide a promising immunotherapy for melanoma in the future.

Cytotoxic T lymphocyte responses against melanocytes and melanoma

Background

Vitiligo is a common toxicity associated with immunotherapy for melanoma. Cytotoxic T lymphocytes (CTLs) against melanoma commonly target melanoma-associated antigens (MAAs) which are also expressed by melanocytes. To uncouple vitiligo from melanoma destruction, it is important to understand if CTLs can respond against melanoma and melanocytes at different levels.

Methods

To understand the dichotomous role of MAA-specific CTL, we characterized the functional reactivities of established CTL clones directed to MAAs against melanoma and melanocyte cell lines.

Results

CTL clones generated from melanoma patients were capable of eliciting MHC-restricted, MAA-specific lysis against melanocyte cell lines as well as melanoma cells. Among the tested HLA-A*0201-restricted CTL clones, melanocytes evoked equal to slightly higher degranulation and cytolytic responses as compared to melanoma cells. Moreover, MAA-specific T cells from vaccinated patients responded directly ex vivo to melanoma and melanocytes. Melanoma cells express slightly higher levels of MART-1 and gp100 than melanocytes as measured by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and immunohistochemistry.

Conclusions

Our data suggest that CTLs respond to melanoma and melanocytes equally in vitro and directly ex vivo.

Crystal structures of HLA-A*0201 complexed with Melan-A/MART-1(26(27L)-35) peptidomimetics reveal conformational heterogeneity and highlight degeneracy of T cell recognition

There is growing interest in using tumor associated antigens presented by class I major histocompatibility complex (MHC-I) proteins as cancer vaccines. As native peptides are poorly stable in biological fluids, researchers have sought to engineer synthetic peptidomimetics with greater biostability. Here, we demonstrate that antigenic peptidomimetics of the Melan-A/MART-1(26(27L)-35) melanoma antigen adopt strikingly different conformations when bound to MHC-I, highlighting the degeneracy of T cell recognition and revealing the challenges associated with mimicking native peptide conformation.

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.

Isolation, establishment, and characterization of ex vivo equine melanoma cell cultures

Gray horses spontaneously develop metastatic melanomas that resemble human disease, and this is often accompanied with metastasis to other organs. Unlike in other species, the establishment of primary equine melanoma cultures that could be used to develop new therapeutic approaches has remained a major challenge. The purpose of the study was to develop a protocol for routine isolation and cultivation of primary equine melanocytes. Melanoma tissues were excised from 13 horses under local anesthesia, mainly from the perianal area. The melanoma cells were isolated from the melanoma tissue by serial enzymatic digestion using dispase and collagenase. Out of the 13 excised melanomas, cell cultures from eight melanomas were established, which corresponded to a success rate 62%. These cells showed different degrees of melanin pigmentation. Characterization of these cells using confocal microscopy, FACs analysis and western blotting showed that they expressed melanoma-associated antigens; Melan-A, MAGE-1, and MAGE-3, and PCNA expression was higher in fast-proliferating isolates. The protocol we developed and established proved successful for routine isolation and cultivation of primary equine melanoma cells. This method provided a large number of primary equine melanoma cells that could be used to study new therapeutic approaches for treatment of equine melanomas.

Cell Technologies in Immunotherapy of Cancer

Tumor growth is accompanied by active immune reactions even on the early stages. Vaccine therapy implies the use of single antigen or combination of antigens, either with or without adjuvants, for the modulation of immune response. N.N. Petrov Institute of Oncology joined the field of antitumor vaccine therapy and related cellular technologies in 1998. The following activities are held: (1) Optimization of the preparation of autologous and allogeneic antitumor vaccines and development of tumor cell culture bank for the experiments on allogeneic vaccination. (2) Clinical evaluation of autologous vaccine therapy by (a) bone marrow precursors of dendritic cells (DCs), which are loaded with tumor lysates; (b) genetically modified tumor cells; (c) intact tumor cells used in combination with various adjuvants (BCG, IL-1beta, and IL-1beta combined with low doses of cyclophosphamide) in patients with disseminated melanoma, metastatic kidney cancer, and colorectal cancer. Total 117 patients have received non-modified vaccine (48 patients: 2-6 intracutaneous BCG injections; 54 patients: 4-6 intracutaneous IL-1beta injections; 15 patients: up to 6 injections of IL-1beta in combination with low doses of cyclophosphamide). Clinical trial of genetically modified vaccine included 59 patients (clinical results: I PR (partial response) / 8 SD (disease stabilization)--melanoma, 2 PR/ 2 MR (minimal response) / 3 SD--renal cancer). Vaccine prepared from tumor cell-activated DC bone marrow precursors was administered to 18 patients (clinical results: 2 MR and 6 SD).

Expression of melanoma-associated antigens in melanoma cell cultures

The efficiency of melanoma immunotherapy appears to depend on both melanoma- and immune system-specific factors. Melanoma-specific factors include melanoma-associated antigen (MAA) expression as well as HLA class I molecule expression. We investigated the expression of five MAA - Melan-A/MART-1, tyrosinase, gp100, MAGE-1 and MAGE-3 - by means of FACS analysis in 50 melanoma cell cultures and compared them to the cultures of human foreskin-derived melanocytes and melanoma cell line UKRV-Mel2. Melan-A, tyrosinase and gp100 expression was frequently reduced in melanoma cell cultures, compared to that in foreskin melanocytes, whereas MAGE-1 and MAGE-3 expression showed variable degree of upregulation, compared to that in foreskin melanocytes. The expression of all tested MAA demonstrated high interindividual variability. We further show that cell cultures derived from the same tissue sample are oligoclonal in nature, by demonstrating the presence of up to three cell populations bearing distinct MAA profile. Analysing samples derived from the same patient but each at a different time point, we show that MAA expression profile changes over time either in positive (increase) or in negative (decrease) direction. Finally, we demonstrate that brain metastasis-derived cell cultures significantly overexpress Melan-A and MAGE-3, compared to primary tumours and other metastatic sites (P-value range: 0.05-0.001). Elucidation of the MAA expression patterns and the kinetics within the same patient as well as during the course of the disease may help improve current and develop new immunotherapeutic strategies.