Intratumoral mast cell number is negatively correlated with tumor size and mitosis in dermatofibrosarcoma protuberans

Keloid pathophysiology: fibroblast or inflammatory disorders?

Background

Keloids are defined as a benign dermal fibroproliferative disorder with no malignant potential. They tend to occur following trivial trauma or any form of trauma in genetically predisposed individuals. Keloids are known to grow beyond the margins of the wound and are common in certain body parts. The pathophysiology of keloid remains unclear, and fibroblasts have been presumed to be the main cells involved in keloid formation. Understanding the mechanism(s) of keloid formation could be critical in the identification of novel therapeutic regimen for the treatment of the keloids.

Objective

To review the pertinent literature and provide updated information on keloid pathophysiology.

Data Source

A Medline PubMed literature search was performed for relevant publications.

Results

A total of 66 publications were retrieved, with relevant publications on the etiology and pathogenesis as well as experimental studies on keloids. All articles were critically analyzed, and all the findings were edited and summarized.

Conclusion

There is still no consensus as on what is the main driving cell to keloid formation. One may, however, hypothesize that keloid formation could be a result of an abnormal response to tissue injury, hence resulting in an exaggerated inflammatory state characterized by entry of excessive inflammatory cells into the wound, including macrophages, lymphocytes, and mast cells. These cells seem to release cytokines including transforming growth factor β1 that stimulate fibroblasts to synthesize excess collagen, which is a hallmark of keloid disease.

Dermatofibrosarcoma Protruberans of the Breast Skin Simulating Mammary Carcinoma

Dermatofibrosarcoma protuberans is a rare soft tissue sarcoma that arises from the dermis and invades deeper tissues. Usually, it behaves as an intermediate grade malignancy but in rare instances, it can metastasize. Frequent occurrences have been observed in trunk and extremities but involvement of the breast has rarely been reported. Therefore, dermatofibrosarcoma protuberans (DFSP) breast often masquerades primary breast malignancy on clinical and radiological grounds. Histomorphology and immunohistochemistry are helpful in making a definitive diagnosis. In the present case, monomorphic spindle cells were seen arranged in classical storiform pattern with large areas of myxoid change. Many times, such myxoid areas pose a diagnostic challenge and necessitate differentiation from other myxoid neoplasms. Herein, immunohistochemistry offers an advantage where tumor cells show strong reactivity for CD34 antibody. Wide surgical excision remains the treatment of choice. The salient clinical features, histogenesis, histomorphology, and immunohistochemical findings have been described with strong emphasis on the diagnostic and therapeutic management of this rare entity.

Mast Cell-Targeted Strategies in Cancer Therapy

Mast cells (MCs) are cells that originate in the bone marrow from pluripotent CD34+ hematopoietic stem cells. Precursors of MCs migrate through the circulation to their target tissues, completing their maturation process into granulated cells under the influence of several microenvironment growth factors. The most important of these factors is the ligand for the c-Kit receptor (c-Kit-R) namely stem cell factor (SCF), secreted mainly by fibroblasts and endothelial cells (ECs). SCF also regulates development, survival and de novo proliferation of MCs. It has already been demonstrated that gain-of-function mutations of gene c-Kit encoding c-Kit-R result in the development of some tumors. Furthermore, MCs are able also to modulate both innate and adaptive immune response and to express the high-affinity IgE receptor following IgE activation. Among the other IgE-independent MC activation mechanisms, a wide variety of other surface receptors for cytokines, chemokines, immunoglobulins, and complement are also described. Interestingly, MCs can stimulate angiogenesis by releasing of several pro-angiogenic cytokines stored in their cytoplasm. Studies published in the last year suggest that angiogenesis stimulated by MCs may play an important role in tumor growth and progression. Here, we aim to focus several biological features of MCs and to summarize new anti-cancer MC-targeted strategies with potential translation in human clinical trials.

Mammalian SIRT2 inhibits keratin 19 expression and is a tumor suppressor in skin

SIRT2 is a member of the mammalian sirtuin family (SIRT1-7). As compared with other sirtuins, SIRT2 is found primarily in the cytoplasm. It regulates multiple physiological processes. However, the precise role of SIRT2 in skin cancer remains unclear. Here, we show that SIRT2 is downregulated in human skin cancer as compared with normal skin. SIRT2 deletion increases tumor growth in mice. SIRT2 knockdown upregulates the stem cell marker Keratin 19 (K19) in keratinocytes. In mice, SIRT2 deletion up-regulates K19 and K15 while it down-regulates the differentiation marker Loricrin in both normal skin and tumors. In skin tumors but not normal skin, SIRT2 deletion up-regulates the stem cell marker CD34 and increases the number of Ki67-positive cells. These findings indicate that SIRT2 is a tumor suppressor in the skin. Our findings add new insights into the role of SIRT2 in the molecular pathogenesis of skin cancer.