Mast Cells Have Prognostic Value in Merkel Cell Carcinoma

Diffuse endocrine system, neuroendocrine tumors and immunity: what's new?

During the last two decades, research into the modulation of immunity by the neuroendocrine system has flourished, unravelling significant effects of several neuropeptides, including somatostatin (SRIH), and especially cortistatin (CST), on immune cells. Scientists have learnt that the diffuse neuroendocrine system can regulate the immune system at all its levels: innate immunity, adaptive immunity, and maintenance of immune tolerance. Compelling studies with animal models have demonstrated that some neuropeptides may be effective in treating inflammatory disorders, such as sepsis, and T helper 1-driven autoimmune diseases, like Crohn's disease and rheumatoid arthritis. Here, the latest findings concerning the neuroendocrine control of the immune system are discussed, with emphasis on SRIH and CST. The second part of the review deals with the immune response to neuroendocrine tumors (NETs). The anti-NET immune response has been described in the last years and it is still being characterized, similarly to what is happening for several other types of cancer. In parallel with investigations addressing the mechanisms by which the immune system contrasts NET growth and spreading, ground-breaking clinical trials of dendritic cell vaccination as immunotherapy for metastatic NETs have shown in principle that the immune reaction to NETs can be exploited for treatment.

Higher intratumoral expression of CD1a, tryptase, and CD68 in a follicular variant of papillary thyroid carcinoma compared to adenomas: correlation with clinical and pathological parameters

BACKGROUND

In a number of human malignancies, the presence of lymphocytic infiltration in or around tumor tissue is commonly considered to be part of the host tumor immune response. An association between thyroid carcinoma and chronic inflammation has been described. This relationship is not fully understood, so we performed a systematic study on a follicular variant of papillary thyroid carcinoma (FVPTC), to evaluate the type and distribution of certain immunological cells and their relationship with prognostic factors.

METHODS

We selected 91 consecutive cases of FVPTC, in which we evaluated the presence of three different immunological cells: dendritic cells (DC), immature CD1a+ and mature DC-Lamp+; mast cells (MC), tryptase+; and macrophages (M), CD68+, in the intratumoral, peritumoral, and extratumoral areas. As a control we analyzed 44 cases of thyroid adenomas (A).

RESULTS

In the intratumoral and peritumoral areas, the expression of CD1a, tryptase, and CD68 was significantly higher in FVPTC than in adenomas. Expression of CD1a and tryptase was comparable in the extratumoral compartment, whereas CD68 expression in the extratumoral area was significantly higher in FVPTC than in adenoma (p=0.0015). DC-Lamp expression was not significantly different among the intra-tumor, peri-tumor, and extra-tumor areas of FVPTC or adenoma. It was also very interesting that nonencapsulated FVPTC were more positive to tryptase.

CONCLUSION

We highlight a higher presence of immunological cells in carcinomas than in adenomas. On this basis, it is possible to speculate that these inflammatory elements could be involved in tumor progression and invasion, as appears to be the case for MC and M.

Mast cells in tumor microenvironment promotes the in vivo growth of pancreatic ductal adenocarcinoma

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer death. No effective therapy is currently available for PDAC because of the lack of understanding of the mechanisms leading to its growth and development. Inflammatory cells, particularly mast cells, have been shown to play key roles in some cancers. We carried out this study to test the hypothesis that mast cells in the tumor microenvironment are essential for PDAC tumorigenesis.

EXPERIMENTAL DESIGN

The presence of inflammatory cells at various stages of PDAC development was determined in a spontaneous mouse model of PDAC (K-ras(G12V)). The importance of mast cells was determined using orthotopically implanted PDAC cells in mast cell-deficient Kit(w-sh/w-sh) mice and further confirmed by reconstitution of wild-type bone marrow-derived mast cells. Clinical relevance was assessed by correlating the presence of mast cells with clinical outcome in patients with PDAC.

RESULTS

In the spontaneous mouse model of PDAC (K-ras(G12V)), there was an early influx of mast cells to the tumor microenvironment. PDAC tumor growth was suppressed in mast cell-deficient Kit(w-sh/w-sh) mice, but aggressive PDAC growth was restored when PDAC cells were injected into mast cell-deficient mice reconstituted with wild-type bone marrow-derived mast cells. Mast cell infiltration into the tumor microenvironment was predictive of poor prognosis in patients with PDAC.

CONCLUSIONS

Mast cells play an important role in PDAC growth and development in mouse models and are indicative of poor prognosis in humans, which makes them a potential novel therapeutic target.

The significant role of mast cells in cancer

Mast cells (MC) are a bone marrow-derived, long-lived, heterogeneous cellular population that function both as positive and negative regulators of immune responses. They are arguably the most productive chemical factory in the body and influence other cells through both soluble mediators and cell-to-cell interaction. MC are commonly seen in various tumors and have been attributed alternatively with tumor rejection or tumor promotion. Tumor-infiltrating MC are derived both from sentinel and recruited progenitor cells. MC can directly influence tumor cell proliferation and invasion but also help tumors indirectly by organizing its microenvironment and modulating immune responses to tumor cells. Best known for orchestrating inflammation and angiogenesis, the role of MC in shaping adaptive immune responses has become a focus of recent investigations. MC mobilize T cells and antigen-presenting dendritic cells. They function as intermediaries in regulatory T cells (Treg)-induced tolerance but can also modify or reverse Treg-suppressive properties. The central role of MC in the control of innate and adaptive immunity endows them with the ability to tune the nature of host responses to cancer and ultimately influence the outcome of disease and fate of the cancer patient.

New insights into merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare aggressive cutaneous malignancy of the elderly and immunocompromised populations. The clinical presentation of MCC is nonspecific, with the majority of cases presenting as localized skin involvement. Histologically and immunophenotypically, MCC is defined by both neuroendocrine and epithelial differentiation. Recently, the Merkel cell polyomavirus has been implicated in the pathogenesis of MCC. In addition, there have been numerous studies evaluating the histologic and immunohistochemical characteristics of MCC as they relate to diagnosis and prognosis. The purpose of this paper is to review the most salient and clinically relevant updates in the pathogenesis and histologic features of MCC. Specific attention is given to the clinical and histologic predictors of prognosis, staging, and the controversies concerning sentinel lymph node biopsy and therapy.

Crosstalk between mast cells and pancreatic cancer cells contributes to pancreatic tumor progression

PURPOSE

To assess the clinical and pathologic significance of mast cell infiltration in human pancreatic cancer and evaluate crosstalk between mast cells and cancer cells in vitro.

EXPERIMENTAL DESIGN

Immunohistochemistry for tryptase was done on 53 pancreatic cancer specimens. Mast cell counts were correlated with clinical variables and survival. Serum tryptase activity from patients with cancer was compared with patients with benign pancreatic disease. In vitro, the effect of pancreatic cancer-conditioned medium on mast cell migration was assessed. The effect of conditioned medium from the human mast cell line, LAD-2, on cancer and normal ductal cell proliferation was assessed by thymidine incorporation. Matrigel invasion assays were used to evaluate the effect of mast cell-conditioned medium on cancer cell invasion in the presence and absence of a matrix metalloproteinase inhibitor, GM6001.

RESULTS

Mast cell infiltration was significantly increased in pancreatic cancer compared with normal pancreatic tissue (11.4 +/- 6.7 versus 2.0 +/- 1.4, P < 0.001). Increased infiltrating mast cells correlated with higher grade tumors (P < 0.0001) and worse survival. Patients with pancreatic cancer had elevated serum tryptase activity (P < 0.05). In vitro, AsPC1 and PANC-1 cells induced mast cell migration. Mast cell-conditioned medium induced pancreatic cancer cell migration, proliferation, and invasion but had no effect on normal ductal cells. Furthermore, the effect of mast cells on cancer cell invasion was, in large part, matrix metalloproteinase-dependent.

CONCLUSIONS

Tumor-infiltrating mast cells are associated with worse prognosis in pancreatic cancer. In vitro, the interaction between mast cells and pancreatic cancer cells promotes tumor growth and invasion.

CD117 is not a useful marker for diagnosing atypical fibroxanthoma

Atypical fibroxanthoma (AFX) is a rare skin tumor that generally pursues an indolent course despite its alarming histological appearances. It is important for the pathologist to distinguish this neoplasm from more aggressive lesions that may show very similar histological features. Recently, it has been suggested that demonstration of CD117 is of value in identifying AFX. To test this hypothesis, 50 cases of AFX were stained immunohistochemically for CD117 to determine the diagnostic value of this antibody. Cases were also stained for tryptase to identify mast cells, which are CD117 positive. In addition, S100 and CD1a stains were performed to assess any possible contribution of melanocytes or Langerhans cells to CD117 staining. Only 1 of 50 AFXs (2%) showed CD117 positivity in the neoplastic cells, but all tumors demonstrated included CD117- and tryptase-positive mast cells in similar distribution. CD117 is only rarely stainable in the neoplastic cells of AFX and is therefore not useful in identifying these tumors. Mast cells are also CD117 positive, frequently present in AFX, and can lead to misinterpretation. Using immunohistochemistry for mast cell tryptase may be of value where there is doubt as to the nature of CD117-positive cells in neoplasms.

T-regulatory cells shift from a protective anti-inflammatory to a cancer-promoting proinflammatory phenotype in polyposis

T-regulatory (Treg) cells play a major role in cancer by suppressing protective antitumor immune responses. A series of observations (from a single laboratory) suggest that Treg cells are protective in cancer by virtue of their ability to control cancer-associated inflammation in an interleukin (IL)-10-dependent manner. Here, we report that the ability of Treg cells to produce IL-10 and control inflammation is lost in the course of progressive disease in a mouse model of hereditary colon cancer. Treg cells that expand in adenomatous polyps no longer produce IL-10 and instead switch to production of IL-17. Aberrant Treg cells from polyp-ridden mice promote rather than suppress focal mastocytosis, a critical tumor-promoting inflammatory response. The cells, however, maintain other Treg characteristics, including their inability to produce IL-2 and ability to suppress proliferation of stimulated CD4 T cells. By promoting inflammation and suppressing T-helper functions, these cells act as a double-edged knife propagating tumor growth.

Merkel cell carcinoma: review

Merkel cell carcinoma (MCC) is synonymous with primary cutaneous neuroendocrine carcinoma. It tends to affects elderly whites, but there is also an increased incidence among immunosuppressed patients. The recent identification of a novel polyomavirus associated with the tumor has stimulated renewed interest in its pathogenesis. MCC tends to show classic histologic features of a neuroendocrine carcinoma and is often positive for CK20, but nonclassic cytologic findings and unusual immunophenotypes may be observed and can lead to a diagnostic confusion. MCC needs to be distinguished from other primary cutaneous tumors with a small cell appearance and metastatic tumors. Surgical excision is the treatment of choice, but radiation therapy has also found to be effective. Sentinel lymph node biopsy has become an integral part of the staging of patients with MCC.

Vascular density has prognostic value in Merkel cell carcinoma

Merkel cell carcinomas are aggressive tumours for which histological prognostic factors need to be established. This study examines the prognostic role of vascular density, based on CD34 immunohistochemical staining in Merkel cell carcinoma. Thirty-six cases of Merkel cell carcinoma were immunohistochemically stained for the endothelial marker CD34. Vascular density was assessed in the tumor and stroma with a Chalkley eyepiece graticule. The scores of vascular density were correlated with other clinical and histological parameters to determine the prognostic significance of tumor vascularity. Increased vascular density was shown to be significantly associated with a worse prognosis (P = 0.005). A 1-unit increase in total vessel score was associated with a 3.9 times increase in the risk of death (95% hazard ratio confidence limits 1.50-10.32). Other factors associated with a worse outcome included tumor size (P = 0.05), the presence of lymphovascular invasion (P = 0.03), and tumor mast cell count (P < 0.002). Increased vascular density is associated with a worse prognosis in Merkel cell carcinomas. Assessment of vascular density may assist in predicting clinical behavior in these tumors and in evaluating the effects of adjuvant therapy.

AllergoOncology: the role of IgE-mediated allergy in cancer

Epidemiological studies have suggested inverse associations between allergic diseases and malignancies. As a proof of concept for the capability of immunoglobulin E (IgE) to destruct tumor cells, several experimental strategies have evolved to specifically target this antibody class towards relevant tumor antigens. It could be demonstrated that IgE antibodies specific to overexpressed tumor antigens have been superior to any other immunoglobulin class with respect to antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis (ADCP) reactions. In an alternative approach, IgE nonspecifically attached to tumor cells proved to be a powerful adjuvant establishing tumor-specific immune memory. Active Th2 immunity could also be achieved by applying an oral immunization regimen using mimotopes, i.e. epitope mimics of tumor antigens. The induced IgE antibodies could be cross-linked by live tumor cells leading to tumoricidic mediator release. Thus, IgE antibodies may not only act in natural tumor surveillance, but could possibly also be exploited for tumor control in active and passive immunotherapy settings. Thereby, eosinophils, mast cells and macrophages can be armed with the cytophilic IgE and become potent anti-tumor effectors, able to trace viable tumor cells in the tissues. It is strongly suggested that the evolving new field AllergoOncology will give new insights into the role of IgE-mediated allergy in malignancies, possibly opening new avenues for tumor therapy.