In situ expression of transforming growth factor beta is associated with melanoma progression and correlates with Ki67, HLA-DR and beta 3 integrin expression

Latent-Transforming Growth Factor β-Binding Protein 1/Transforming Growth Factor β1 Complex Drives Antitumoral Effects upon ERK5 Targeting in Melanoma

Melanoma is the deadliest skin cancer, with a poor prognosis in advanced stages. Available treatments have improved survival, although long-term benefits still are unsatisfactory. The mitogen-activated protein kinase extracellular signal-regulated kinase 5 (ERK5) promotes melanoma growth, and ERK5 inhibition determines cellular senescence and the senescence-associated secretory phenotype. Here, latent-transforming growth factor β-binding protein 1 (LTBP1) mRNA was found to be up-regulated in A375 and SK-Mel-5 BRAFV600E melanoma cells after ERK5 inhibition. In keeping with a key role of LTBP1 in regulating transforming growth factor β (TGF-β), TGF-β1 protein levels were increased in lysates and conditioned media of ERK5-knockdown (KD) cells, and were reduced upon LTBP1 KD. Both LTBP1 and TGF-β1 proteins were increased in melanoma xenografts in mice treated with the ERK5 inhibitor XMD8-92. Moreover, treatment with conditioned media from ERK5-KD melanoma cells reduced cell proliferation and invasiveness, and TGF-β1-neutralizing antibodies impaired these effects. In silico data sets revealed that higher expression levels of both LTBP1 and TGFB1 mRNA are associated with better overall survival of melanoma patients, and that increased LTBP1 or TGF-β1 expression proved a beneficial role in patients treated with anti-PD1 immunotherapy, making a possible immunosuppressive role of LTBP1/TGF-β1 unlikely upon ERK5 inhibition. This study, therefore, identifies additional desirable effects of ERK5 targeting, providing evidence of an ERK5-dependent tumor-suppressive role of TGF-β in melanoma.

Establishment of SLC7A11-knockout mouse and its preliminary investigation in melanoma

Solute carrier family 7 member 11 (SLC7A11)/xCT is an amino acid transporter that mediates the cystine uptake and glutamate export, participates in several malignant tumors' progression. However, the role of SLC7A11 on the occurrence and development of melanoma still remains unclear. Here, the transcribed mRNA encoding for Cas9 and sgRNA targeting SLC7A11 in vitro were microinjected into zygotes, to establish the SLC7A11 knockout (KO) mice (SLC7A11-/-). Further, we conducted melanoma-bearing mice using the metastatic melanoma cell line (B16-F10) to observe the melanoma development. There was no off-target in KO mice detected by T7E1 cleavage assay. The results showed that the tumor volume of KO mice was significantly lower than that of SLC7A11+/+ (WT) mice at 8d, 10d, 12d, 14d, and 16d (P < 0.05). The tumors of WT appeared to more disorganized morphology, more unbalanced nuclear-cytoplasmic ratio, less defined boundary, and increased tumor necrosis. And after SLC7A11 deletion, the expression of CXCL9 and TLR6 were significantly up-regulated, and that of NOS2 and CCL8 were significantly down-regulated (P < 0.01). Additionally, Ki67 immunostaining revealed lower proliferating cells in the tumors of SLC7A11 KO mice compared to WT mice. In summary, the deletion of SLC7A11 significantly inhibited the development of melanoma. Our results provide direct evidence to identify SLC7A11 as a novel target for molecular therapy and prognosis judgment of melanoma.

HYDIN mutation status as a potential predictor of immune checkpoint inhibitor efficacy in melanoma

BACKGROUND

The advent of immune checkpoint inhibitors (ICIs) has altered the outlook for cancer treatment. The estimation of predictive biomarkers could contribute to maximizing the benefits from ICIs treatment. Here, we explored the association between HYDIN mutations (HYDIN-MUT) in melanoma and ICIs efficacy.

METHODS

Clinical data and sequencing data from published studies were utilized to assess the association between HYDIN-MUT and the efficacy of ICIs treatment in melanoma patients.

RESULTS

Compared to other tumor types, HYDIN (36.14%) has the highest mutation rate in melanoma patients. In the anti-PD-1 treated cohort (n = 254), the HYDIN-MUT patients had a longer OS after ICIs treatment than the HYDIN wild-type (HYDIN-WT) patients (HR = 0.590 [95% CI, 0.410-0.847], P = 0.004); the objective response rate (ORR) and durable clinical benefit (DCB) were increased in patients with HYDIN-MUT (ORR = 46.25, DCB = 56.00%) compared to patients with HYDIN-WT (ORR = 30.99%, DCB = 42.76%) (ORR: P = 0.019; DCB: P = 0.060). In the anti-CTLA4 treated cohort (n = 174), HYDIN-MUT patients achieved significantly longer OS than HYDIN-WT patients (HR = 0.549 [95% CI, 0.366-0.823], P = 0.003); the proportion of ORR and DCB in HYDIN-MUT patients was significantly higher than that in HYDIN-WT patients (ORR 40.54% vs. 14.42%, P = 0.031; DCB 45.76% vs. 22.22%, P = 0.002). Further gene set enrichment analysis demonstrated that DNA repair and anti-tumor immunity were significantly enhanced in HYDIN-MUT patients.

CONCLUSIONS

HYDIN mutations are a potential predictive biomarker of ICIs efficacy in melanoma patients.

Genetic dominance of transforming growth factor-β1 polymorphisms in chronic liver disease

Chronic liver disease (CLD) is an extremely common clinical condition accompanied by sustained inflammatory response leading to tissue damage. Transforming growth factor-β1 (TGF-β1) is known as a master immune regulator in CLDs, but the association between TGF-β1 polymorphisms and CLD risk is controversial and inconclusive, and the genetic dominance of CLDs remains unknown. In this study, the relationship between TGF-β1 polymorphisms and CLD susceptibility is systematically analyzed based on 35 eligible studies. Individuals with the TGF-β1-509 allele (TT or CT) or codon 10 allele (Pro/Pro) show an increased risk of CLDs. Subgroup analyses indicate TGF-β1-509C/T has a significant correlation with cirrhosis and chronic hepatitis C, codon 10 is associated with chronic hepatitis B occurrence, and codon 25 exhibits a relationship with autoimmune hepatitis risk. Missense mutations in G29E, A105S, D191N, and F321L of TGF-β1 are the genetic factors of HCC susceptibility. Furthermore, the TGF-β1 gene expression is significantly elevated in CLD patients, and the TGF-β1 codon 263 is located close to the region where the TGF-β1 dimerization interacts, indicating the TGF-β1 codon 263 variant may affect the secretion of TGF-β1 by altering its dimerization. Together, our findings provide new insights into the immune regulator gene TGF-β1 polymorphisms as susceptibility factors for CLD occurrence and regulators for TGF-β1 expression, which have implications for the regulation of immune factors during CLD development.

Integration of miRNA:mRNA Co-Expression Revealed Crucial Mechanisms Modulated in Immunogenic Cancer Cell Death

Immunogenic cell death (ICD) in cancer represents a functionally unique therapeutic response that can induce tumor-targeting immune responses. ICD is characterized by the exposure and release of numerous damage-associated molecular patterns (DAMPs), which confer adjuvanticity to dying cancer cells. The spatiotemporally defined emission of DAMPs during ICD has been well described, whereas the epigenetic mechanisms that regulate ICD hallmarks have not yet been deeply elucidated. Here, we aimed to examine the involvement of miRNAs and their putative targets using well-established in vitro models of ICD. To this end, B cell lymphoma (Mino) and breast cancer (MDA-MB-231) cell lines were exposed to two different ICD inducers, the combination of retinoic acid (RA) and interferon-alpha (IFN-α) and doxorubicin, and to non ICD inducers such as gamma irradiation. Then, miRNA and mRNA profiles were studied by next generation sequencing. Co-expression analysis identified 16 miRNAs differentially modulated in cells undergoing ICD. Integrated miRNA-mRNA functional analysis revealed candidate miRNAs, mRNAs, and modulated pathways associated with Immune System Process (GO Term). Specifically, ICD induced a distinctive transcriptional signature hallmarked by regulation of antigen presentation, a crucial step for proper activation of immune system antitumor response. Interestingly, the major histocompatibility complex class I (MHC-I) pathway was upregulated whereas class II (MHC-II) was downregulated. Analysis of MHC-II associated transcripts and HLA-DR surface expression confirmed inhibition of this pathway by ICD on lymphoma cells. miR-4284 and miR-212-3p were the strongest miRNAs upregulated by ICD associated with this event and miR-212-3p overexpression was able to downregulate surface expression of HLA-DR. It is well known that MHC-II expression on tumor cells facilitates the recruitment of CD4+ T cells. However, the interaction between tumor MHC-II and inhibitory coreceptors on tumor-associated lymphocytes could provide an immunosuppressive signal that directly represses effector cytotoxic activity. In this context, MHC-II downregulation by ICD could enhance antitumor immunity. Overall, we found that the miRNA profile was significantly altered during ICD. Several miRNAs are predicted to be involved in the regulation of MHC-I and II pathways, whose implication in ICD is demonstrated herein for the first time, which could eventually modulate tumor recognition and attack by the immune system.

Comprehensive Analysis of Regulatory Network for LINC00472 in Clear Cell Renal Cell Carcinoma

Renal cell carcinoma (RCC) accounts for about 2% to 3% of adult malignancies, and clear cell renal cell carcinoma (ccRCC) is the most common and aggressive type of kidney cancer. It accounts for 75% of all kidney tumors. Although new targeted drugs continue to appear, they are still not suitable for all patients. Therefore, an in-depth study of the molecular mechanism of the development of ccRCC and exploration of new targets for the treatment of ccRCC will help to achieve precise treatment for ccRCC. With the development of molecular research, the study of long noncoding RNA (LncRNA) has given us a new understanding of tumors. Although LncRNA does not encode proteins, it directly interacts with proteins in various signaling pathways and affects cell functions. Therefore, it is of great significance to study the mechanism of LncRNA in ccRCC. The expression level of Linc00472 in ccRCC tissues is significantly lower than adjacent normal tissues, and its low expression is closely related to Furman's high grade. The low expression of Linc00472 is associated with poor prognosis in patients with ccRCC. The results of protein interaction and functional enrichment analysis indicate that genes upregulated in renal clear cell carcinoma may play a major role. Analysis of target gene prediction results showed that Linc00472 may be used as ceRNA in the miR-24-3p-HLA-DPB1 pathway, miR-24-3p-CXCL9 pathway, miR-221-3p-C3aR1-VEGFR2 pathway, miR-17-5p-HLA-DQA1/HLA-DQB1 pathway, and miR-17-5p-C3aR1/C5aR1-VEGFR2 pathway which play important functions. In addition, the regulatory relationship between miR-24-3p and TNFR2 (TNFRSF1B), CD36, and COL4A1 should also be noted. The value of Linc00472 in the diagnosis and treatment of ccRCC is worthy of further study.

Expression levels of HLA-DR in acute myeloid leukemia: implications for antigenicity and clinical outcome

Low human leukocyte antigen (HLA)-DR expression might compromise CD4⁺ T-cell-mediated anti-tumor immunity. Its immunological and clinical significance however remain undefined in non-promyelocytic acute myeloid leukemia (AML). Taking advantage of mass spectrometry-based immunopeptidome analysis of primary AML samples (n = 31), we studied the implications of low HLA-DR expression for antigen presentation and analyzed its association with disease characteristics and survival within a cohort of 399 AML patients. Remarkably, overall HLA-DR/DQ immunopeptidome diversity was preserved in AML with low HLA-DR expression (HLA-DR^low AML) and was associated with a shift in HLA-DR/DQ allotype abundances (HLA-DQ to HLA-DR/DQ ligand ratio 0.36 vs 0.19 in HLA-DR^low and HLA-DR^high patients, respectively). Consistent with unimpaired antigenicity, survival was similar in HLA-DR^low and HLA-DR^high patients. Demonstrating for the first time that overall HLA-DR/DQ antigen presentation is preserved in HLA-DR^low AML, our findings provide a rationale for the non-inferior outcome observed in HLA-DR^low AML patients.

Role of Human Leukocyte Antigen System as A Predictive Biomarker for Checkpoint-Based Immunotherapy in Cancer Patients

Recent advances in cancer immunotherapy have clearly shown that checkpoint-based immunotherapy is effective in a small subgroup of cancer patients. However, no effective predictive biomarker has been identified so far. The major histocompatibility complex, better known in humans as human leukocyte antigen (HLA), is a very polymorphic gene complex consisting of more than 200 genes. It has a crucial role in activating an appropriate host immune response against pathogens and tumor cells by discriminating self and non-self peptides. Several lines of evidence have shown that down-regulation of expression of HLA class I antigen derived peptide complexes by cancer cells is a mechanism of tumor immune escape and is often associated to poor prognosis in cancer patients. In addition, it has also been shown that HLA class I and II antigen expression, as well as defects in the antigen processing machinery complex, may predict tumor responses in cancer immunotherapy. Nevertheless, the role of HLA in predicting tumor responses to checkpoint-based immunotherapy is still debated. In this review, firstly, we will describe the structure and function of the HLA system. Secondly, we will summarize the HLA defects and their clinical significance in cancer patients. Thirdly, we will review the potential role of the HLA as a predictive biomarker for checkpoint-based immunotherapy in cancer patients. Lastly, we will discuss the potential strategies that may restore HLA function to implement novel therapeutic strategies in cancer patients.

Immunosuppression and Immunotargeted Therapy in Acute Myeloid Leukemia - The Potential Use of Checkpoint Inhibitors in Combination with Other Treatments

INTRODUCTION

Immunotherapy by using checkpoint inhibitors is now tried in the treatment of several malignancies, including Acute Myeloid Leukemia (AML). The treatment is tried both as monotherapy and as a part of combined therapy.

METHODS

Relevant publications were identified through literature searches in the PubMed database. We searched for (i) original articles describing the results from clinical studies of checkpoint inhibition; (ii) published articles describing the immunocompromised status of AML patients; and (iii) published studies of antileukemic immune reactivity and immunotherapy in AML.

RESULTS

Studies of monotherapy suggest that checkpoint inhibition has a modest antileukemic effect and complete hematological remissions are uncommon, whereas combination with conventional chemotherapy increases the antileukemic efficiency with acceptable toxicity. The experience with a combination of different checkpoint inhibitors is limited. Thalidomide derivatives are referred to as immunomodulatory drugs and seem to reverse leukemia-induced immunosuppression, but in addition, they have direct inhibitory effects on the AML cells. The combination of checkpoint targeting and thalidomide derivatives thus represents a strategy for dual immunotargeting together with a direct antileukemic effect.

CONCLUSION

Checkpoint inhibitors are now tried in AML. Experimental studies suggest that these inhibitors should be combined with immunomodulatory agents (i.e. thalidomide derivatives) and/or new targeted or conventional antileukemic treatment. Such combinations would allow dual immunotargeting (checkpoint inhibitor, immunomodulatory agents) together with a double/triple direct targeting of the leukemic cells.

Expressions of HLA Class II Genes in Cutaneous Melanoma Were Associated with Clinical Outcome: Bioinformatics Approaches and Systematic Analysis of Public Microarray and RNA-Seq Datasets

Major histocompatibility complex (MHC) class II molecules, encoded by human leukocyte antigen (HLA) class II genes, play important roles in antigen presentation and initiation of immune responses. However, the correlation between HLA class II gene expression level and patient survival and disease progression in cutaneous melanoma is still under investigation. In the present study, we analyzed microarray and RNA-Seq data of cutaneous melanoma from The Cancer Genome Atlas (TCGA) using different bioinformatics tools. Survival analysis revealed higher expression level of HLA class II genes in cutaneous melanoma, especially HLA-DP and -DR, was significantly associated with better overall survival. Furthermore, the expressions of HLA class II genes were most closely associated with survival in cutaneous melanoma as compared with other cancer types. The expression of HLA class II co-expressed genes, which were found to associate with antigen processing, immune response, and inflammatory response, was also positively associated with overall survival in cutaneous melanoma. Therefore, the results indicated that increased HLA class II expression may contribute to enhanced anti-tumor immunity and related inflammatory response via presenting tumor antigens to the immune system. The expression pattern of HLA class II genes may serve as a prognostic biomarker and therapeutic targets in cutaneous melanoma.

Gene Expression Indicates Altered Immune Modulation and Signaling Pathway Activation in Ovarian Cancer Patients Resistant to Topotecan

Epithelial ovarian cancer (EOC) is one of the deadliest gynecological malignancies. Topotecan remains an essential tool in second-line therapy; even so, most patients develop resistance within a short period of time. We aimed to identify biomarkers of topotecan resistance by using gene expression signatures derived from patient specimens at surgery and available subsequent responses to therapy. Gene expression was collected for 1436 patients and 10,103 genes. Based on disease progression, patients were categorized as responders/nonresponders depending on their progression free survival (PFS) state at 9, 12, 15 and 18 months after surgery. For each gene, the median expression was compared between responders and nonresponders for two treatment regimens (chemotherapy including/excluding topotecan) with Mann–Whitney U test at each of the four different PFS cutoffs. Statistical significance was accepted in the case of p < 0.05 with a fold change (FC) ≥ 1.44. Four genes (EPB41L2, HLA-DQB1, LTF and SFRP1) were consistently overexpressed across multiple PFS cutoff times in initial tumor samples of patients with disease progression following topotecan treatment. A common theme linked to topotecan resistance was altered immune modulation. Genes associated with disease progression after systemic chemotherapy emphasize the role of the initial organization of the tumor microenvironment in therapy resistance. Our results uncover biomarkers with potential utility for patient stratification.

CD74 regulates complexity of tumor cell HLA class II peptidome in brain metastasis and is a positive prognostic marker for patient survival

Despite multidisciplinary local and systemic therapeutic approaches, the prognosis for most patients with brain metastases is still dismal. The role of adaptive and innate anti-tumor response including the Human Leukocyte Antigen (HLA) machinery of antigen presentation is still unclear. We present data on the HLA class II-chaperone molecule CD74 in brain metastases and its impact on the HLA peptidome complexity.We analyzed CD74 and HLA class II expression on tumor cells in a subset of 236 human brain metastases, primary tumors and peripheral metastases of different entities in association with clinical data including overall survival. Additionally, we assessed whole DNA methylome profiles including CD74 promoter methylation and differential methylation in 21 brain metastases. We analyzed the effects of a siRNA mediated CD74 knockdown on HLA-expression and HLA peptidome composition in a brain metastatic melanoma cell line.We observed that CD74 expression on tumor cells is a strong positive prognostic marker in brain metastasis patients and positively associated with tumor-infiltrating T-lymphocytes (TILs). Whole DNA methylome analysis suggested that CD74 tumor cell expression might be regulated epigenetically via CD74 promoter methylation. CD74high and TILhigh tumors displayed a differential DNA methylation pattern with highest enrichment scores for antigen processing and presentation. Furthermore, CD74 knockdown in vitro lead to a reduction of HLA class II peptidome complexity, while HLA class I peptidome remained unaffected.In summary, our results demonstrate that a functional HLA class II processing machinery in brain metastatic tumor cells, reflected by a high expression of CD74 and a complex tumor cell HLA peptidome, seems to be crucial for better patient prognosis.

Pro-tumor activities of macrophages in the progression of melanoma

Macrophages are located in essentially all tissues due to their “janitor” function. Macrophages can exert either anti- or pro-tumor activities depending upon the specific tumor microenvironment they inhabit. Substantial evidence indicates that macrophages, owing to their plasticity, can be reeducated to adopt a protumoral phenotype within a tumor microenvironment through the help of growth factors in the microenvironment and intercellular interactions. As the lethality of malignant melanoma is due to its aggressive capacity for metastasis and resistance to therapy, considerable effort has gone toward treatment of metastatic melanoma. In the present review, we focus on the pro-tumor activities of macrophages in melanoma. Based upon the information presented in this review it is anticipated that new therapies will soon be developed that target pro-tumor activities of macrophages for use in the treatment of melanoma.

HLA class II antigen-processing pathway in tumors: Molecular defects and clinical relevance

The human leukocyte antigen (HLA) class II antigen-processing machinery (APM) presents to cognate CD4⁺ T-cells antigenic peptides mainly generated from exogeneous proteins in the endocytic compartment. These CD4⁺ T cells exert helper function, but may also act as effector cells, thereby recognizing HLA class II antigen-expressing tumor cells. Thus, HLA class II antigen expression by tumor cells influences the tumor antigen (TA)-specific immune responses and, depending on the cancer type, the clinical course of the disease. Many types of human cancers express HLA class II antigens, although with marked differences in their frequency. Some types of cancer lack HLA class II antigen expression, which could be due to structural defects or deregulation affecting different components of the complex HLA class II APM and/or from lack of cytokine(s) in the tumor microenvironment. In this review, we have summarized the information about HLA class II antigen distribution in normal tissues, the structural organization of the HLA class II APM, their expression and regulation in malignant cells, the defects, which have been identified in malignant cells, and their functional and clinical relevance.

Frequent HLA class I alterations in human prostate cancer: molecular mechanisms and clinical relevance

Reduced expression of HLA class I is an important immune escape mechanism from cytotoxic T cells described in various types of malignancy. It often correlates with poor prognosis and resistance to therapy. However, current knowledge about the frequency, underlying molecular mechanisms, and prognostic value of HLA class I and II alterations in prostate cancer (PC) is limited. Immunohistochemical analysis demonstrated that 88 % of the 42 studied cryopreserved prostate tumors have at least one type of HLA alteration as compared to adjacent normal prostate epithelium or benign hyperplasia. Total loss of HLA-I expression found in 50 % of tumors showed an association with increased incidence of tumor relapse, perineural invasion, and high D'Amico risk. The remaining HLA-I-positive tumors demonstrated locus and allelic losses detected in 26 and 12 % of samples, respectively. Loss of heterozygosity at chromosome 6 was detected in 32 % of the studied tumors. Molecular analysis revealed a reduced expression of B2M, TAP2, tapasin and NLRC5 mRNA in microdissected HLA-I-negative tumors. Analysis of twelve previously unreported cell lines derived from neoplastic and normal epithelium of cancerous prostate revealed different types of HLA-I aberration, ranging from locus and/or allelic downregulation to a total absence of HLA-I expression. The high incidence of HLA-I loss observed in PC, caused by both regulatory and structural defects, is associated with more aggressive disease development and may pose a real threat to patient health by increasing cancer progression and resistance to T-cell-based immunotherapy.

PD-L1 and HLA Class I Antigen Expression and Clinical Course of the Disease in Intrahepatic Cholangiocarcinoma

PURPOSE

More effective therapy is needed for intrahepatic cholangiocarcinoma (ICC). The encouraging clinical results obtained with checkpoint molecule-specific monoclonal antibodies (mAb) have prompted us to investigate whether this type of immunotherapy may be applicable to ICC. The aims of this study were to determine whether (i) patients mount a T-cell immune response to their ICC, (ii) checkpoint molecules are expressed on both T cells and tumor cells, and (iii) tumor cells are susceptible to recognition by cognate T cells.

EXPERIMENTAL DESIGN

Twenty-seven ICC tumors were analyzed for (i) lymphocyte infiltrate, (ii) HLA class I and HLA class II expression, and (iii) PD-1 and PD-L1 expression by T cells and ICC cells, respectively. The results of this analysis were correlated with the clinicopathologic characteristics of the patients investigated.

RESULTS

Lymphocyte infiltrates were identified in all tumors. PD-L1 expression and HLA class I antigen expression by ICC cells was observed in 8 and 11, respectively, of the 27 tumors analyzed. HLA class I antigen expression correlated with CD8(+) T-cell infiltrate. Furthermore, positive HLA class I antigen expression in combination with negative/rare PD-L1 expression was associated with favorable clinical course of the disease.

CONCLUSIONS

ICC patients are likely to mount a T-cell immune response against their own tumors. Defects in HLA class I antigen expression in combination with PD-L1 expression by ICC cells provide them with an immune escape mechanism. This mechanism justifies the implementation of immunotherapy with checkpoint molecule-specific mAbs in patients bearing ICC tumors without defects in HLA class I antigen expression.

HLA class II antigen expression in colorectal carcinoma tumors as a favorable prognostic marker

The goal of this study was to determine the frequency of HLA class II antigen expression in colorectal carcinoma (CRC) tumors, its association with the clinical course of the disease, and the underlying mechanism(s). Two tissue microarrays constructed with 220 and 778 CRC tumors were stained with HLA-DR, DQ, and DP antigen-specific monoclonal antibody LGII-612.14, using the immunoperoxidase staining technique. The immunohistochemical staining results were correlated with the clinical course of the disease. The functional role of HLA class II antigens expressed on CRC cells was analyzed by investigating their in vitro interactions with immune cells. HLA class II antigens were expressed in about 25% of the 220 and 21% of the 778 tumors analyzed with an overall frequency of 23%. HLA class II antigens were detected in 19% of colorectal adenomas. Importantly, the percentage of stained cells and the staining intensity were significantly lower than those detected in CRC tumors. However, HLA class II antigen staining was weakly detected only in 5.4% of 37 normal mucosa tissues. HLA class II antigen expression was associated with a favorable clinical course of the disease. In vitro stimulation with interferon gamma (IFNγ) induced HLA class II antigen expression on two of the four CRC cell lines tested. HLA class II antigen expression on CRC cells triggered interleukin-1β (IL-1β) production by resting monocytes. HLA class II antigen expression in CRC tumors is a favorable prognostic marker. This association may reflect stimulation of IL-1β production by monocytes.

Halofuginone inhibits the establishment and progression of melanoma bone metastases

TGF-β derived from bone fuels melanoma bone metastases by inducing tumor secretion of prometastatic factors that act on bone cells to change the skeletal microenvironment. Halofuginone is a plant alkaloid derivative that blocks TGF-β signaling with antiangiogenic and antiproliferative properties. Here, we show for the first time that halofuginone therapy decreases development and progression of bone metastasis caused by melanoma cells through the inhibition of TGF-β signaling. Halofuginone treatment of human melanoma cells inhibited cell proliferation, phosphorylation of SMAD proteins in response to TGF-β, and TGF-β-induced SMAD-driven transcription. In addition, halofuginone reduced expression of TGF-β target genes that enhance bone metastases, including PTHrP, CTGF, CXCR4, and IL11. Also, cell apoptosis was increased in response to halofuginone. In nude mice inoculated with 1205 Lu melanoma cells, a preventive protocol with halofuginone inhibited bone metastasis. The beneficial effects of halofuginone treatment were comparable with those observed with other anti-TGF-β strategies, including systemic administration of SD208, a small-molecule inhibitor of TGF-β receptor I kinase, or forced overexpression of Smad7, a negative regulator of TGF-β signaling. Furthermore, mice with established bone metastases treated with halofuginone had significantly less osteolysis than mice receiving placebo assessed by radiography. Thus, halofuginone is also effective in reducing the progression of melanoma bone metastases. Moreover, halofuginone treatment reduced melanoma metastasis to the brain, showing the potential of this novel treatment against cancer metastasis.

Induction of monocyte chemoattractant protein-1 and interleukin-10 by TGFbeta1 in melanoma enhances tumor infiltration and immunosuppression

Melanoma progression is associated with the expression of different growth factors, cytokines, and chemokines. Because TGFβ1 is a pleiotropic cytokine involved not only in physiologic processes but also in cancer development, we analyzed in A375 human melanoma cells, the effect of TGFβ1 on monocyte chemoattractant protein-1 (MCP-1) and interleukin-10 (IL-10) expression, two known factors responsible for melanoma progression. TGFβ1 increased the expression of MCP-1 and IL-10 in A375 cells, an effect mediated by the cross-talk between Smad, PI3K (phosphoinositide 3-kinase)/AKT, and BRAF-MAPK (mitogen activated protein kinase) signaling pathways. Supernatants from TGFβ1-treated A375 cells enhanced MCP-1-dependent migration of monocytes, which, in turn, expressed high levels of TGF,β1, bFGF, and VEGF mRNA. Moreover, these supernatants also inhibited functional properties of dendritic cells through IL-10-dependent mechanisms. When using in vitro, the TGFβ1-blocking peptide P144, TGFβ1-dependent Smad3 phosphorylation, and expression of MCP-1 and IL-10 were inhibited. In vivo, treatment of A375 tumor-bearing athymic mice with P144 significantly reduced tumor growth, associated with a lower macrophage infiltrate and decreased intratumor MCP-1 and VEGF levels, as well as angiogenesis. Finally, in C57BL/6 mice with B16-OVA melanoma tumors, when administered with immunotherapy, P144 decreased tumor growth and intratumor IL-10 levels, linked to enhanced activation of dendritic cells and natural killer cells, as well as anti-OVA T-cell responses. These results show new effects of TGFβ1 on melanoma cells, which promote tumor progression and immunosuppression, strongly reinforcing the relevance of this cytokine as a molecular target in melanoma.

Biomarkers: the useful and the not so useful--an assessment of molecular prognostic markers for cutaneous melanoma

Among individuals with localized (Stage I-II) melanoma, stratifying patients by a number of phenotypic variables (e.g., depth of invasion, ulceration) yields a wide range of 10-year melanoma-specific survival rates. With the possible exception of Ki-67, no molecular assessment is routinely used. However, there have been a tremendous number of studies assessing protein expression by immunohistochemistry toward the goal of better prediction of recurrence. In a previous systematic review, which required publication of multivariable prognostic models as a strict inclusion criterion, we identified 37 manuscripts that collectively reported on 62 proteins. Data for 324 proteins extracted from 418 manuscripts did not meet our inclusion criteria for that study, but are revisited here, emphasizing trends of protein expression across either melanocytic lesion progression or gradations of tumor thickness. These identified 101 additional proteins that stratify melanoma, organized according to the Hanahan and Weinberg functional capabilities of cancer.

JWA regulates melanoma metastasis by integrin alphaVbeta3 signaling

JWA, a newly identified novel microtubule-associated protein (MAP), was recently demonstrated to be indispensable for the rearrangement of actin cytoskeleton and activation of MAPK cascades induced by arsenic trioxide (As(2)O(3)) and phorbol ester (PMA). JWA depletion blocked the inhibitory effect of As(2)O(3) on HeLa cell migration, but enhanced cell migration after PMA treatment. As cancer cell migration is a hallmark of tumor metastasis and the functional role of JWA in cancer metastasis is not understood, here we show that JWA has an important role in melanoma metastasis. Our data demonstrated that JWA knockdown increased the adhesion and invasion abilities of melanoma cells. Furthermore, JWA knockdown in B16-F10 and A375 melanoma cells significantly promoted the formation and growth of metastatic colonies in vivo. Moreover, in the tumor biopsies from human melanoma patients, JWA expression was significantly decreased in malignant melanoma compared with normal nevi. In addition, we found that JWA knockdown could intensify tumor integrin alpha(V)beta(3) signaling by regulating nuclear factor Sp1. These findings suggest that JWA suppresses melanoma metastasis and may serve a potential therapeutic target for human melanoma.

HLA class II antigen expression in conjunctival precancerous lesions and squamous cell carcinomas

PURPOSE

The expression of human leukocyte antigen (HLA) class II molecules on the cell surface is necessary for the presentation of peptide antigens to helper CD4 T lymphocytes of the immune system. We studied the immunoexpression of HLA class II antigen in conjunctival precursor lesions and conjunctival squamous cell carcinomas.

METHODS

HLA class II antigen expression was analyzed in 8 conjunctival dysplasias, 6 carcinomas in situ and in 7 conjunctival squamous cell carcinomas, by immunoperoxidase staining with monoclonal antibody to HLA class II antigen on the archival clinical samples. Immunoanalysis was done by a semi quantitative method based on the intensity of staining and the percentage of stained cells.

RESULTS

HLA class II antigen immunoexpression was heterogeneous in 8 conjunctival dysplasias and in 6 carcinoma in situ and negative in 7 conjunctival squamous cell carcinomas.

CONCLUSIONS

Human leukocyte class II antigen immunoexpression is decreased in conjunctival precancerous and squamous cell carcinomas.

Transforming growth factor-beta activation promotes genetic context-dependent invasion of immortalized melanocytes

Accumulation of distinct sets of genetic/epigenetic alterations is thought to contribute to stepwise progression of human cutaneous melanomas. We found evidence of frequent tumor cell autonomous transforming growth factor-beta (TGF-beta) signal activation in both premalignant and malignant stages of human cutaneous melanoma histogenesis and investigated its potential causative roles using human organotypic skin cultures. PTEN deficiency and Braf activation, two common coincident genetic alterations found in primary cutaneous melanomas, were first introduced into human melanocytes previously immortalized by the SV40 large T antigen and telomerase. These changes individually supported anchorage-independent growth and conferred benign, hyperplastic growth in a skin-like environment. In addition, PTEN deficiency combined with Braf activation together induced a melanoma in situ-like phenotype without dermal invasion. Further addition of cell autonomous TGF-beta activation in the context of PTEN deficiency and Braf activation promoted dermal invasion in skin cultures without significantly promoting proliferation in vitro and in vivo. This proinvasive phenotype of cell autonomous TGF-beta activation is genetic context-dependent, as hyperactivating the TGF-beta type I receptor without PTEN deficiency and Braf activation failed to induce an invasive behavior. Evidence of genetic interactions among PTEN deficiency, Braf activation, and cell autonomous TGF-beta activation shows that distinct stages of human melanoma are genetically tractable in the proper tissue architecture.

The molecular basis of melanomagenesis and the metastatic phenotype

The last two decades have seen spectacular advances in our understanding of the biology of melanoma and, in particular, have elucidated the mechanisms operative in disease initiation and progression. With respect to the former, the genetics of melanoma and in particular the impact of genetic defects on dysregulation of the cell cycle are key issues in malignant transformation and are a major focus of this review. With respect to the latter, consideration also is given to the acquisition of growth factor autonomy and the capacity for invasion and metastasis from the standpoint of cell adhesion, motility, and matrix digestion. These events have specific morphologic correlates that will be briefly addressed. Where relevant, we will address certain of the modern pharmacogenetic strategies that flow from these novel observations concerning melanoma biology.

Circulating serum levels of angiogenic factors and vascular endothelial growth factor receptors 1 and 2 in melanoma patients

Angiogenesis is essential for tumor progression and metastasis; however, the angiogenesis regulators that are biologically relevant for melanoma are still unknown. In this study, we analyzed the circulating serum levels of potent angiogenic factors, including vascular endothelial growth factor (VEGF), angiogenin, transforming growth factor-beta1 and VEGF receptors, VEGFR1 and VEGFR2, in human melanoma patients. One hundred and fourteen patients with histopathologically verified cutaneous melanoma at different stages and 30 healthy controls were investigated. Serum levels of angiogenic factors and VEGF receptors were quantitatively analyzed by solid-phase enzyme-linked immunosorbent assay. The age of the patients (61 men and 53 women) ranged from 18 to 80 years; median age was 51 years. Serum transforming growth factor-beta1 (P < 0.001), VEGF (P = 0.006) and VEGFR1 (P = 0.007) levels were significantly higher in patients with melanoma than in the control group. No significant differences, however, exist in the serum angiogenin and VEGFR2 levels between melanoma patients and the controls. The positive correlations of elevated serum levels of transforming growth factor-beta1, VEGF and VEGFR1 with advanced stages of disease were found. Significant relationship was found only between serum levels of VEGF and VEGFR2. Elevated serum transforming growth factor-beta1 (P < 0.001) and VEGF levels (P = 0.0012) were found to be poor prognostic factors. Serum level of angiogenin and VEGF receptors, however, had no effect on survival. Our data suggest that the angiogenic serum factors, including VEGF, transforming growth factor-beta1 and VEGFR1, but not angiogenin and VEGFR2 were increased in melanoma patients, especially associated with advanced disease stages. The mechanism of VEGF regulation of angiogenesis may in part be due to enhanced proliferation of VEGFRs, especially VEGFR1.

T Cell Tolerance to Tumors and Cancer Immunotherapy

It is widely recognized that the immune system plays a role in cancer progression and that some tumors are inherently immunogenic. The identification of tumor-associated antigens (TAAs) has stimulated research focused on immunotherapies to mediate the regression of established tumors. Cancer-specific immunity has traditionally been aimed at activating CD8+ cytotoxic T lymphocytes (CTLs) directed against major histocompatibility complex (MHC) class I-binding peptide epitopes. Other approaches utilize T cell adoptive therapy where autologous, tumor-specific T cells propagated in vitro are transferred back into recipients. However, these strategies have met with limited success in part due to the regulatory mechanisms of T cell tolerance, which poses a considerable challenge to cancer immunotherapy. Our laboratory utilizes the TRansgenic Adenocarcinoma of the Mouse Prostate (TRAMP) model, a murine model of prostate cancer, to study mechanisms of T cell tolerization to tumor antigens. We previously demonstrated that upon encounter with their cognate antigen in the tumor microenvironment, naive T cell become tolerized. Our ongoing studies are testing whether provision of CD4+ T cells can enhance tumor immunity by preventing CD8+ T cell tolerance. A greater understanding of the interaction between various tumor-specific T cell subsets will facilitate the design of novel approaches to stimulate a more potent antitumor immune response.

TIM-3 is expressed in melanoma cells and is upregulated in TGF-beta stimulated mast cells

Many studies detect elevated numbers of mast cells in tumors, but it is still controversial whether they are beneficial or detrimental for tumor cells. Furthermore, many tumors, such as melanomas, produce large quantities of transforming growth factor (TGF)-beta and during tumorigenesis the apoptotic and growth-inhibitory effects of TGF-betas are lost. Based on these data we investigated the gene expression changes in TGF-betaI-treated human mast cells with DNA microarray and detected 45 differentially regulated genes, among them T-cell immunoglobulin and mucin domain-containing protein 3 (TIM-3). As the major sources of TIM-3 ligand galectin-9 are not tumor cells, but rather mast cells, this raises the possibility of an autocrine mechanism resulting in local immunosuppression through the elevated TIM-3 expression by TGF-betaI. Interestingly, not only melanoma tissue sections contained TIM-3-positive mast cells, but we detected this protein also in melanoma cells. Furthermore, TIM-3 was expressed in both WM35 and HT168-M1 melanoma cell lines at a higher level than in isolated epidermal melanocytes, which can contribute to the lower adhering capacity of tumor cells. In conclusion, the immunoregulatory molecule TIM-3 in TGF-beta-stimulated mast cells and melanoma cells may support the survival of this tumor type.

Metastatic potential of melanomas defined by specific gene expression profiles with no BRAF signature

The molecular biology of metastatic potential in melanoma has been studied many times previously and changes in the expression of many genes have been linked to metastatic behaviour. What is lacking is a systematic characterization of the regulatory relationships between genes whose expression is related to metastatic potential. Such a characterization would produce a molecular taxonomy for melanoma which could feasibly be used to identify epigenetic mechanisms behind changes in metastatic behaviour. To achieve this we carried out three separate DNA microarray analyses on a total of 86 cultures of melanoma. Significantly, multiple testing correction revealed that previous reports describing correlations of gene expression with activating mutations in BRAF or NRAS were incorrect and that no gene expression patterns correlate with the mutation status of these MAPK pathway components. Instead, we identified three different sample cohorts (A, B and C) and found that these cohorts represent melanoma groups of differing metastatic potential. Cohorts A and B were susceptible to transforming growth factor-beta (TGFbeta)-mediated inhibition of proliferation and had low motility. Cohort C was resistant to TGFbeta and demonstrated high motility. Meta-analysis of the data against previous studies linking gene expression and phenotype confirmed that cohorts A and C represent transcription signatures of weakly and strongly metastatic melanomas, respectively. Gene expression co-regulation suggested that signalling via TGFbeta-type and Wnt/beta-catenin pathways underwent considerable change between cohorts. These results suggest a model for the transition from weakly to strongly metastatic melanomas in which TGFbeta-type signalling upregulates genes expressing vasculogenic/extracellular matrix remodelling factors and Wnt signal inhibitors, coinciding with a downregulation of genes downstream of Wnt signalling.

Mechanisms of the self/non-self-survey in the defense against cancer: Potential for chemoprevention?

When compared to a reference population, several large epidemiological studies with long-term follow-up have reported a three- to five-fold increased risk of neoplasia amongst patients who have received organ transplants, with an incidence curve that rises in a linear fashion with time. The relationship between the immune system and cancer is complex. The ability to discriminate "self" from "non-self" is one of the central roles of the immune system. Since tumors arise from transformation of host cells, it is not surprising that some aspects of tumor immunity resemble autoimmunity. The immune response to tumors shares aspects of both self- and non-self-immune recognition. What accounts for the apparent failure of immunity? In this review article, we address the role of the self/non-self-survey in the immune response to tumors, we describe mechanisms of immune surveillance against tumor cells, and we discuss models of ignorance, tolerance and tumor evasion of the immune response. The overall aim of the article is to demonstrate the scope for prevention of cancer in individuals at increased risk of developing malignancy due to immune compromise. Interventional strategies may involve the use of pro-differentiation agents such as retinoids, modifiers of polyamine biosynthesis or inhibitors of cyclooxygenase isozymes.

Transforming growth factor-beta and malignant melanoma: molecular mechanisms

Transforming growth factor family members (TGF-beta) are secretory polypeptides that have dual tumor-suppressor and oncogenic effects. They signal through kinase receptor complexes on the cell surface, which phosphorylate cytoplasmic mediators (SMADs). Upon phosphorylation, SMADs march to the nucleus and interact with coactivators or corepressors to mediate the transcriptional regulation of several genes resulting in diverse effects. In tumorigenesis, malignant cells escape from the tumor-suppressive effects of TGF-beta by mutational inactivation or dysregulated expression of the molecular components in TGF-beta signaling pathway. Although melanoma cells are resistant to the tumor-suppressive effects of TGF-beta, there are no detectable defects at the receptor/SMAD level. Therefore, in these lesions, it is possible that TGF-beta effects occur independently of TGF-beta receptor/SMAD pathway. This review seeks to examine the present knowledge about TGF-beta receptor/SMAD signaling pathway and its related genes (SMADs, SKI, Filamin, endoglin, Follistatin, and other molecules) in melanomas.

Comparative Histopathology of Grey-Horse-Melanoma and Human Malignant Melanoma

Equine melanoma shows striking features particularly with regard to clinical development in grey horses: in contrast to malignant melanoma in humans and in solid coloured horses that are characterized by early onset of metastasis, pigment cell tumours display almost benign clinical features in ageing grey horses. Through evolution, grey horses appear to be in a favourable position in regard to the biological behaviour of melanomas. Yet unknown factors inhibiting or retarding early melanoma metastasis may be responsible for this phenomenon. In this study, immunostaining profiles and histopathologic patterns of equine vs. human melanotic tumours were compared. In addition, the expression of melanoma markers currently used in human melanoma detection and characterization were evaluated for their applicability in equine melanoma diagnosis. Immunohistopathologic investigations revealed that benign grey horse melanomas share common features with human blue nevi and with human malignant desmoplastic melanomas, whereas their resemblance to other types of human cutaneous malignant melanomas is less pronounced. Our data equally underline that S-100, proliferating cell nuclear antigen (PCNA), HMB-45, Ki-67, T-311 and CD44 can serve as reliable markers for horse melanomas. Further investigations aiming at identifying factors retarding metastasis in affected grey horses are needed, as they may contribute to the development of novel treatment strategies for human malignant melanoma.

Evaluation of inflammatory infiltrate and fibrogenic cytokines in pseudopelade of Brocq suggests the involvement of T-helper 2 and 3 cytokines

BACKGROUND

Pseudopelade of Brocq (PB) is an acquired progressive cicatricial alopecia which is characterized by some distinctive clinical features. It may represent either a distinct entity, i.e. an idiopathic primary scarring alopecia, or the end stage of various forms of scarring alopecia such as discoid lupus erythematosus (DLE) or lichen planopilaris (LPP).

OBJECTIVES

The aim of the study was to evaluate a set of patients with a clinically defined PB, to ascertain whether their PB was idiopathic or secondary, and then to study the phenotype of the inflammatory infiltrate and the presence of any fibrogenic and antifibrogenic cytokines to identify idiopathic or secondary forms in more detail.

METHODS

Twelve female patients with PB were studied by means of histology, direct immunofluorescence (DIF) and immunohistochemistry, by using monoclonal antibodies to cell markers (lymphocyte subtypes, Langerhans cells, macrophages, fibroblasts, mastocytes and activation markers) and fibrogenic and antifibrogenic cytokines.

RESULTS

Using histology and DIF, we diagnosed two cases as DLE and three cases as LPP. Seven cases had nonspecific histology or DIF appearances and were classified as noncharacterized pseudopelade (NCPB). Two major phenotypic patterns of dermal infiltrate were identified by immunohistochemistry. These were: (i) a conspicuous infiltrate of CD3+ cells with a high CD4+/CD8+ ratio, variable numbers of macrophages, mast cells and fibroblasts always fewer than lymphocytes; (ii) an infiltrate of CD3+ cells with variable CD4+/CD8+ ratio and conspicuous amounts of macrophages, mast cells and fibroblasts, more numerous than infiltrating lymphocytes. The first pattern was typical of DLE and LPP, the second one was typical of NCPB. Fibrogenic cytokines were observed in all cases, but basic fibroblastic growth factor (bFGF) and transforming growth factor (TGF)-beta were more strongly expressed in NCPB. Interferon (IFN)-gamma was found in LPP.

CONCLUSIONS

In our PB patients we identified five of 12 secondary PB and seven of 12 idiopathic PB by means of histology and DIF. The phenotypic pattern of infiltration allowed us to further differentiate secondary (richer in lymphocytes) from idiopathic PB (richer in resident cells). The pattern of cytokine expression showed the presence of fibrogenic molecules (interleukins 4 and 6, bFGF and TGF-beta) in all cases, suggesting the involvement of mechanisms mediated by T-helper 2 and 3 cytokines in PB.

Major histocompatibility antigens and antigen-processing molecules in retinoblastoma

BACKGROUND

Malignant transformation of cells is frequently associated with abnormalities in human leukocyte antigen (HLA) expression. These abnormalities may play a role in the clinical course of the disease, because HLAs mediate interactions of tumor cells with cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. Retinoblastoma is the most common intraocular malignant tumor in childhood and is characterized by direct spread to the optic nerve and orbit as well as hematogeneous and lymphatic spread. Little is known about the role of HLA expression in the progression of this malignant disease.

METHODS

HLA Class I antigen, beta2-microglobulin (beta2-m), HLA Class II antigens, and the antigen-processing molecules (APMs) of the HLA Class I pathway, including proteasomal subunits (low-molecular mass polypeptide 2 [LMP-2] and LMP-10), the transporter-associated protein (TAP-1) subunit, the binding protein tapasin, and the chaperone molecule calnexin, were studied in 30 archival retinoblastoma specimens by immunohistochemistry. Immunoanalysis was performed based on the International Histocompatibility Working Group Project Description.

RESULTS

HLA Class I antigen, beta2-m, HLA Class II antigen, and APMs were positive in 12 tumors with no invasion and were decreased in 13 tumors with choroidal and optic nerve invasion. The difference in HLA and APM expression between the 2 groups was statistically significant (P < 0.001).

CONCLUSIONS

Decreased expression of HLA was observed in aggressive tumors and in poorly differentiated tumors. The current findings support a role for both CTLs and NK cell-mediated control of tumor growth in the clinical course of retinoblastoma.

Transforming growth factor-beta1 inhibits tumor growth in a mouse melanoma model by down-regulating the plasminogen activation system

The degradation of basement membranes by tumor cells involves secretion and activation of proteinases, such as matrix metalloproteinases (MMPs) and the plasminogen activation system (uPA, tPA, PAI-1), and results from an imbalance between their inhibitors and activators, controlled by various growth factors or cytokines. Among them, the TGF-beta family is one of the most intriguing because it has been reported either to decrease or promote cancer progression. In the present paper, we studied the effect of TGF-beta1 in a mouse melanoma model. In vivo, TGF-beta1 inhibited tumor growth after subcutaneous injection of B16F1 cells in syngenic mice. In vitro, TGF-beta1 did not alter B16F1 cell proliferation, but strongly decreased their migration through Matrigel-coated membranes. The protease production was analyzed by zymography, Western blot, or RT-PCR. MMP-2 and TIMP-2 expression were not altered by TGF-beta1. In contrast, TGF-beta1 triggered a large decrease of uPA and tPA, as well as a decrease of uPA and uPAR mRNAs. By Western blot and RT-PCR analyses, TGF-beta1 was shown to induce a strong increase of PAI-1 synthesis. Collectively, these results suggest that TGF-beta1 may inhibit melanoma tumor growth by specifically decreasing plasmin activity of tumor cells and play a protective role during the earliest stages of tumor progression.

Does the immune system see tumors as foreign or self?

Given the vast number of genetic and epigenetic changes associated with carcinogenesis, it is clear that tumors express many neoantigens. A central question in cancer immunology is whether recognition of tumor antigens by the immune system leads to activation (i.e., surveillance) or tolerance. Paradoxically, while strong evidence exists that specific immune surveillance systems operate at early stages of tumorigenesis, established tumors primarily induce immune tolerance. A unifying hypothesis posits that the fundamental processes of cancer progression, namely tissue invasion and metastasis, are inherently proinflammatory and thus activating for innate and adaptive antitumor immunity. To elude immune surveillance, tumors must develop mechanisms that block the elaboration and sensing of proinflammatory danger signals, thereby shifting the balance from activation to tolerance induction. Elucidation of these mechanisms provides new strategies for cancer immunotherapy.

HLA class II antigen expression in uveal melanoma: correlation with clinicopathological features

The authors examined the immunoexpression of human leukocyte (HLA) class II antigen in uveal melanomas and correlated with the cell types, largest tumour dimension and extrascleral invasion. HLA class II antigen expression was analysed in 45 primary uveal melanoma lesions by immunoperoxidase staining with monoclonal antibody. Immunoanalysis was done by a semi-quantitative method according to the International Histocompatibility Working Group, Project description. The results were correlated clinicopathologically. Among the 45-uveal melanomas, 17 were spindle cell types, 16 were mixed cell types and 12 were epithelioid cell types. Among the 35 tumours with no extrascleral extension, HLA class II antigen was decreased in (100%) 35/35 tumours. Among the 10 tumours with extrascleral extension, HLA class II antigen was positive in the 60% (6/10) tumours with liver metastasis and decreased in 40% (4/10) tumours with no liver metastasis. HLA class II antigen was negative in 94% (16/17) spindle cell melanomas. Decreased HLA class II immunoreactivity in tumours with no extrascleral extension was significant (P<0.001). Negative HLA class II immunoreactivity in the spindle cell melanoma was significant (P<0.001). There was no correlation with largest tumour diameter and immunoreactivity. HLA class II antigen is an independent prognostic marker in uveal melanoma. Thus, HLA class II antigen expression in uveal melanoma in relation to prognosis and cell types are similar to HLA class I antigen expression, where downregulation and presence of spindle cell melanoma correlates with favourable outcome. This may have important implications with respect to proposed T cell based immunotherapy.

Tumor-associated antigen profiling in breast and ovarian cancer: mRNA, protein or T cell recognition?

PURPOSE

The absence of tumor-associated antigens (TAA) which might elicit an immune response is one reason for the disappointing results of therapeutical vaccines in cancer patients. Moreover, impaired expression of MHC class-I and components involved in antigen processing, such as TAP-1, -2, LMP-2, -7, and MECL-1, may lead to tumor escape from immune recognition. Expression profiling of TAA is one approach towards the design of well-defined and individualized anti-tumor vaccines.

METHODS

Quantitative polymerase chain reaction (qRT-PCR) is the method of choice to characterize immunologically relevant properties of individual tumors. However, the application of qRT-PCR as a surrogate parameter for the expression of TAAs depends upon the assumption that the level of an mRNA species correlates with the cellular level of the protein it encodes. Therefore, we additionally analyzed TAA expression by immunofluorescence and T cell recognition.

RESULTS

In the present study we were unable to confirm that impaired TAP-1 or -2 (transporter associated with antigen processing) expression characterized at the mRNA level is an appropriate surrogate parameter for down-regulated MHC class-I expression in breast cancer. In addition, we analyzed the expression pattern of TAAs in breast and ovarian cancer cell lines. Besides the well-known over-expression of HER-2/neu, CEA, and MUC-1, multiple antigens of the MAGE-family were frequently co-expressed. We investigated whether detection of TAAs by qRT-PCR correlates with monoclonal antibody staining, and which method could predict T cell recognition. We demonstrated a correlation between tumor cell lysis by HLA-A*0201-restricted, MUC-1-specific CTL and threshold levels of MUC-1-specific mRNA.

CONCLUSION

MUC-1 is an example that TAA profiling by RT-PCR and flow cytometry can fail to correlate with each other and are of limited value in the prediction of T cell recognition.

HLA-DR antigen-negative acute myeloid leukemia

Human leukocyte antigen (HLA) Class II antigens are variably expressed on acute myeloid leukemia (AML) blasts. The biological and clinical significance of HLA Class II antigen expression by AML cells is not known. Therefore, we sought to characterize cases of AML without detectable HLA-DR expression. Samples from 248 consecutive adult AML patients were immunophenotyped by multiparameter flow cytometry at diagnosis. HLA-DR antigens were not detected on AML cells from 43 patients, including 20 with acute promyelocytic leukemia (APL), and 23 with other subtypes of AML. All APL cases had t(15;17), but there were no characteristic chromosome abnormalities in non-APL cases. No direct expression of other antigens was identified in HLA-DR-negative APL and non-APL cases. Interestingly, cells from three HLA-DR-negative non-APL patients had similar morphology to that of the hypogranular variant of APL. This morphology, however, was not present in any HLA-DR-positive AML cases. Treatment response was similar in the 23 HLA-DR-negative non-APL and the 205 HLA-DR-positive patients. Finally, relapse was infrequently associated with changes in HLA-DR antigen expression, as the HLA-DR antigen was lost at relapse in only 4% of HLA-DR-positive cases, and was gained at relapse in only 17% of HLA-DR-negative cases. We conclude that HLA-DR-negative AML includes approximately equal numbers of APL and non-APL cases, and that the morphology of HLA-DR-negative non-APL cases can mimic the hypogranular variant of APL. The diagnosis of APL cannot be based on morphology and lack of HLA-DR antigen expression; rather, it requires cytogenetic or molecular confirmation.

The tumor microenvironment: a potential arbitrator of the tumor suppressive and promoting actions of TGFbeta

Transforming growth factor beta (TGFbeta) members are secreted in biologically inactive complexes that must be activated in order to enable binding to their cell surface receptors. Interestingly, many of the proteins that can activate TGFbeta have been implicated in either suppressing or promoting tumorigenesis. Included among these are matrix proteins (thrombospondin-1), receptors (integrins alphanubeta6 and alphanubeta8) and proteases (matrix metalloproteases and plasmin). These proteins cannot only activate TGFbeta, but can also modulate cell responsiveness to TGFbeta. In this section, we review data highlighting the complexity and bidirectionality of TGFbeta matrix interactions within the tumor microenvironment, and propose that these dynamic interactions are a critical spatial and temporal determinant of the effects of TGFbeta on tumorigenesis.

HLA expression in uveal melanoma: there is no rule without some exception

A decrease in the expression of HLA antigens is considered a characteristic of tumor progression and is considered an important tumor-escape mechanism. In general, HLA Class I expression is even further decreased on metastases. Tumor cells that loose their HLA Class I antigens become less susceptible to lysis by specific T cells, but may become more sensitive to Natural Killer cells. Loss of HLA Class I can be observed at different levels, i.e. total loss of Class I, loss of expression of one locus or one haplotype, or even one specific allele. We studied HLA expression on human uveal melanoma and observed that loss of expression of a locus or one or more alleles is a common phenomenon. However, in contrast with the commonly accepted paradigm, loss of HLA Class I expression on the uveal melanoma was not associated with tumor cell escape and a worse survival, but with a better survival of the patients involved. We hypothesize that this is due to the route of metastases formation: in uveal melanoma, spreading of metastases is purely hematogeneous, and it is quite possible that NK-cell mediated surveillance of tumor cells in the blood is the underlying mechanism. This is supported by our finding that metastases of uveal melanoma have a high HLA Class I expression, leading to our conclusion that uveal melanoma is an exception to the general rule regarding HLA Class I expression in tumor immunology.

Circulating immunoglobulin-bound transforming growth factor beta at a late tumour-bearing stage impairs antigen-specific responses of CD4+ T cells

In order to elucidate the mechanisms by which tumour-specific CD4+ T-cell responses are impaired during tumour development, an attempt was made to identify factors which impair CD4+ T-cell responses at a late tumour-bearing stage. Plasma from mice bearing B16 melanoma for 30 days (plasma d30) showed a more profound immunosuppressive effect on the in vitro proliferation of unrelated antigen-specific CD4+ T cells in the presence of both antigen and antigen-presenting cells (APC) than plasma from naïve mice. The level of plasma transforming growth factor (TGF)- was elevated in mice bearing B16 melanoma for 30 days compared with naïve mice, and the suppressive effect of plasma d30 was partially diminished by the neutralization of TGF-. Interestingly, immunoglobulin (IgG)-bound TGF-, but not IgG-unbound TGF-, in plasma d30 was suggested to be responsible for the immunosuppressive activity. In addition, no suppressive effect of plasma d30 was observed when antigen was added as a class II peptide, thus suggesting that the impaired proliferation of CD4+ T cells in the presence of plasma d30 was due to a dysfunction of antigen uptake/processing by APC. Furthermore, dissociation between IgG and TGF- resulted in a loss of the suppressive activity of plasma d30. Taken together, these results suggest that circulating IgG-bound TGF- is, at least in part, responsible for the impaired responses of CD4+ T cells at the late tumour-bearing stage by suppressing antigen uptake/ processing by APC.

Enhanced VEGF production and decreased immunogenicity induced by TGF-beta 1 promote liver metastasis of pancreatic cancer

TGF-betas are multifunctional polypeptides that regulate cell growth and differentiation, extracellular matrix deposition, cellular adhesion properties, angiogenesis and immune functions. In this study, we investigated the effect of TGF-beta1 on liver metastasis and its mechanism by using human pancreatic cancer cell lines Panc-1, Capan-2, and SW1990. Capan-2 and SW1990 cells demonstrated enhanced liver metastatic potential by in vivo splenic injection with TGF-beta1. Consequently, we examined the role of TGF-beta1 on in vitro angiogenesis and received cytotoxicity by peripheral blood mononuclear leukocytes (PBMLs). While TGF-beta1 slightly decreased cell proliferation, it also upregulated VEGF production in all cancer cells examined. The binding of PBMLs to cancer cells and cancer cell cytotoxicity during co-culture with PBMLs were remarkably decreased by treatment with TGF-beta1. Panc-1 cells revealed no liver metastasis despite their high immunogenetic and angiogenetic abilities, which was attributed to a lack of expression of the cell surface carbohydrates that induce attachment to endothelial cells. We concluded that the presence of TGF-beta1 in the microenvironment of tumour site might play an important role in enhancing liver metastasis of pancreatic cancer by modulating the capacity of angiogenesis and immunogenicity.

Expression of integrins, degradative enzymes and their inhibitors in uveal melanoma: differences between in vitro and in vivo expression

Posterior uveal melanoma is the most common intraocular malignancy in adults. Metastasis occurs in approximately 40% of all cases and spread is primarily to the liver. Once secondary hepatic disease has developed the prognosis is poor. Metastasis involves a series of adhesion and de-adhesion events, coupled with regulated tissue degradation to facilitate tumour cell invasion and spread to both local and distant sites. These processes are assisted by the expression of integrins and degradative enzymes by both tumour and host cells. Using a series of 10 uveal melanomas, we investigated the expression of a panel of integrins, degradative enzymes and their inhibitors that have been shown to be associated with metastasis. In addition, we undertook to establish if there might be differential expression in response to growth under artificial conditions. All the tumours expressed matrix metalloproteinases (MMP)-2 and-9, tissue inhibitor of metalloproteases (TIMP)-2, urokinase plasminogen activator (u-PA), plasminogen activator inhibitor (PAI)-1 and PAI-2. Differences in the expression of the integrins alpha1beta1, alpha2beta1 and alpha6beta1 were observed; in particular, these differences appeared to relate to expression as a consequence of growth in culture. In summary, uveal melanoma cells express both degradative enzymes and their respective inhibitors, which are important in metastasis. It would appear that differential expression of integrins is present, probably as a response to in vitro stimulation.

T-cell-directed cancer vaccines: mechanisms of immune escape and immune tolerance

Recent clinical trials using vaccines directed toward tumour-associated antigens (TA) have shown the increasing capacity of vaccines to cause immunologic responses. In fact, strongly reactive TA-specific cytolytic T-lymphocytes and tumour-infiltrating lymphocytes (TIL) can be identified and expanded ex vivo from patients with metastatic melanoma vaccinated with melanoma-associated antigens. Paradoxically, this strong immunological response does not correlate with clinical tumour regression. Proposed mechanisms responsible for this glaring inconsistency are numerous and varied; systemic immunosuppressive as well as local mechanistic factors are implicated. In this review we will critically evaluate the possible mechanisms that allow tumours to escape immune destruction and be tolerated by the immune system. In addition, strategies that may allow further insight into the biology of tumour rejection are discussed, in the hope of deepening the understanding of this phenomenon and enhancing its therapeutic potential.

TGF-beta in uveal melanoma

Uveal melanoma is the most common primary ocular cancer among adults and patients with distant metastases seldom survive longer than a year. Melanomas of the eye have the advantage of growing in the special environment of an immune privileged site and it has long been shown, that the special immunosuppressive properties of the intraocular microenvironment are strongly mediated by cytokines, especially transforming growth factor-beta (TGF-beta). Here, we sought to investigate the presence of TGF-beta in surgically removed uveal melanoma specimens using immunohistochemical methods to verify possible autocrine mechanisms. Immunocytochemistry for pan-TGF-beta and TGF-beta(2) was performed on 13 melanoma specimens using an alkaline phosphatase labeling procedure. Melanocytic origin of the tumors was confirmed by HMB-45 staining. All tissue samples exhibited positive staining using either pan-TGF-beta or TGF-beta(2) antibody regardless of cell-type, size of the tumor, or tumor location. The intensity of staining did not vary significantly within a given tumor. All tumors stained positive against the HMB-45 antibody. Many cytokines have been found to act on melanoma tumors. The presence of the TGF-beta(2) isoform in all specimens points to progressive tumor-growth as has been shown for melanomas of the skin. Based on our immunohistochemical findings and the immunosuppressive properties of TGF-beta, we suppose that ocular melanomas should be able to create their own immunosuppressive environment even in the uvea, which might be a non-privileged site.