Advances in the chemoprevention of non-melanoma skin cancer in high-risk organ transplant recipients

Radix et Rhizoma Ginseng chemoprevents both initiation and promotion of cutaneous carcinoma by enhancing cell-mediated immunity and maintaining redox homeostasis

Background

Radix et Rhizoma Ginseng (thereafter called ginseng) has been used as a medicinal herb for thousands of years to maintain people's physical vitality and is also a non–organ-specific cancer preventive and therapeutic traditional medicine in several epidemiologic and preclinical studies. Owing to few toxic side effects and strong enhancement on body immunity, ginseng has admirable application potential and value in cancer chemoprevention. The study aims at investigating the chemopreventive effects of ginseng on cutaneous carcinoma and the underlying mechanisms.

Methods

The mouse skin cancer model was induced by 7,12-dimethylbenz[a]anthracene/12-O-tetradecanoylphorbol-13-acetate. Ultraperformance liquid chromatography/mass spectrometry was used for identifying various ginsenosides, the main active ingredients of ginseng. Comprehensive approaches (including network pharmacology, bioinformatics, and experimental verification) were used to explore the potential targets of ginseng.

Results

Ginseng treatment inhibited cutaneous carcinoma in terms of initiation and promotion. The content of Rb1, Rb2, Rc, and Rd ginsenosides was the highest in both mouse blood and skin tissues. Ginseng and its active components well maintained the redox homeostasis and modulated the immune response in the model. Specifically, ginseng treatment inhibited the initiation of skin cancer by enhancing T-cell–mediated immune response through upregulating HSP27 expression and inhibited the promotion of skin cancer by maintaining cellular redox homeostasis through promoting nuclear translocation of Nrf2.

Conclusion

According to the study results, ginseng can be potentially used for cutaneous carcinoma as a chemopreventive agent by enhancing cell-mediated immunity and maintaining redox homeostasis with multiple components, targets, and links.

A pediatric case of squamous cell cancer in situ in the setting of sclerodermatous graft-versus-host disease and voriconazole treatment

Sclerodermatous graft-versus-host disease is a subtype of cutaneous chronic graft-versus-host disease that is characterized by sclerosis of the skin and subcutaneous tissue, resulting in debilitating contractures, among other life-threatening complications. Children with sclerodermatous graft-versus-host disease are at high risk of developing nonmelanoma skin cancer because of several risk factors, including young age at transplantation, prolonged immunosuppression, and exposure to photosensitizing antimicrobial prophylaxis such as voriconazole. The immunosuppression required to treat sclerodermatous graft-versus-host disease makes effectively treating nonmelanoma skin cancer and sclerodermatous graft-versus-host disease in the same patient challenging. We describe a challenging case of a 6-year-old boy with a history of sclerodermatous graft-versus-host disease and voriconazole exposure presenting with squamous cell carcinoma in situ on the left temple and actinic keratoses on the scalp treated with topical chemotherapy agents.

Paradoxical oncogenesis--the long-term effects of BRAF inhibition in melanoma

The clinical benefits of BRAF inhibition in patients with advanced-stage BRAF-mutant melanoma are now well established. Although the emergence of cutaneous squamous-cell carcinomas (SCCs) and secondary melanomas in patients on BRAF-inhibitor therapy have been well described, reports are emerging of additional secondary premalignant and malignant events, including RAS-mutant leukaemia, the metastatic recurrence of RAS-mutant colorectal cancer and the development of gastric and colonic polyps. In most cases, paradoxical MAPK activation--resulting from the BRAF-inhibitor-mediated homodimerization and heterodimerization of nonmutant RAF isoforms--seems to underlie the development of these secondary tumours. Although evidence supports that therapy with the simultaneous administration of BRAF and MEK inhibitors abrogates the onset of treatment-induced SCCs, whether combination treatment will limit the emergence of all BRAF-inhibitor-driven pathologies is unclear. In this Review, we describe the clinical and mechanistic manifestations of secondary cancers that have thus far been observed to arise as a consequence of BRAF inhibition. We discuss the concept of pre-existing populations of partly transformed cells with malignant potential that might be present in various organ systems, and the rationale for novel therapeutic strategies for the management of BRAF-inhibitor-induced neoplasia.

Advanced basal cell carcinoma

Basal cell carcinoma (BCC) is the most common skin malignancy worldwide. Ultraviolet light exposure is the best known exogenous factor in BCC development. This is also the target for primary prevention. Advanced BCC include locally advanced tumors and metastatic tumors. Prognosis is worse compared to stage I and II BCCs. Mohs or micrographically controlled surgery is the gold standard of treatment. In patients with tumors that cannot be completely removed radiotherapy was the only alternative in the past. More recently new drugs for targeted therapy of signaling pathways like sonic hedgehog or epidermal growth factor receptor became available. More small molecules are under investigation. Since the complete response rates are limited, future research has to evaluate their combination with surgery.

Hedgehog signaling pathway and its targets for treatment in basal cell carcinoma

Basal cell carcinoma (BCC) of the skin is the most common type of cancer and accounts for up to 40% of all cancers in the US, with a growing incidence rate over recent decades in all developed countries. Surgery is curative for most patients, although it leaves unaesthetic scars, but those that develop locally advanced or metastatic BCC require different therapeutic approaches. Furthermore, patients with BCC present a high risk of developing additional tumors. The increasing economic burden and the morbidity of BCC render primary interest in the development of targeted treatments for this disease. Among the molecular signals involved in the development of BCC, the critical role of the morphogenetic Hedgehog (Hh) pathway has become evident. This pathway is found altered and activated in almost all BCCs, both sporadic and inherited. Given the centrality of the Hh pathway in the pathophysiology of BCC, the primary efforts to identify molecular targets for the topical or systemic treatment of this cancer have focused on the Hh components. Several Hh inhibitors have been so far identified - from the first identified natural cyclopamine to the recently Food and Drug Administration-approved synthetic vismodegib - most of which target the Hh receptor Smoothened (either its function or its translocation to the primary cilium). Other molecules await further characterization (bisamide compounds), while drugs currently approved for other diseases such as itraconazole (an antimicotic agent) and vitamin D3 have been tested on BCC with encouraging results. The outcomes of the numerous ongoing clinical trials are expected to expand the field in the very near future. Further research is needed to obtain drugs targeting downstream components of the Hh pathway (eg, Gli) or to exploit combinatorial therapies (eg, with phosphatidylinositol 3-kinase inhibitors or retinoids) in order to overcome potential drug resistance.