Nonmelanoma skin cancer chemoprevention

Reducing non-melanoma skin cancer risk in renal transplant recipients

With an increasing number of renal transplant recipients (RTRs) and improving patient survival, a higher incidence of non-melanoma skin cancer (NMSC) has been observed. NMSC in RTRs are often more numerous and biologically more aggressive than the general population, thus contributing towards an increase in morbidity and to a lesser degree, mortality. The resultant cumulative health and financial burden is a recognized concern. Proposed strategies in mitigating risks of developing NMSC and early therapeutic options thereof include tailored modification of immunosuppressants in conjunction with sun protection in all transplant patients. This review highlights the clinical and financial burden of transplant-associated skin cancers, carcinogenic mechanisms in association with immunosuppression, importance of skin cancer awareness campaign and integrated transplant skin clinic, and the potential role of chemoprotective agents. A scheme is proposed for primary and secondary prevention of NMSC based on the available evidence.

Demethoxycurcumin: A naturally occurring curcumin analogue with antitumor properties

The eradication of cancer in a patient remains an elusive challenge despite advances in early detection and diagnosis, chemo- and immunotherapy, pinpoint radiation treatments, and expert surgical intervention. Although significant gains have been made in our understanding of cancer cell biology, a definite cure for most cancers does not exist at present. Thus, it is not surprising that the research and medical communities continue to explore the importance and therapeutic potential of natural products in their multimodality cancer treatment approach. Curcuminoids found in turmeric are one such class of natural products that have been extensively investigated for their potential to halt the progression of cancer cell proliferation and, more important, to stop metastasis from occurring. In this review, we examine one curcuminoid (demethoxycurcumin [DMC]) largely because of its increased stability and better aqueous solubility at physiological pH, unlike the more well-known curcuminoid (curcumin), which is largely unabsorbed after oral ingestion. The present review will focus on the signaling pathways that DMC utilizes to modulate the growth, invasion, and metastasis of cancer cells in an effort to provide enhanced mechanistic insight into DMC's action as it pertains to brain, ovarian, breast, lung, skin, and prostate cancer. Additionally, this review will attempt to provide an overview of DMC's mechanism of action by modulating apoptosis, cell cycle, angiogenesis, metastasis, and chemosensitivity. Lastly, it is hoped that increased understanding will be gained concerning DMC's interactive role with microRNA-551a, 5' adenosine monophosphate-activated protein kinase, nuclear factor-κB, Wnt inhibitory factor-1, and heat shock protein 70 to affect the progression of cancer.

Neoplastic Multifocal Skin Lesions: Biology, Etiology, and Targeted Therapies for Nonmelanoma Skin Cancers

Neoplastic skin lesions are multifocal, diffuse skin infiltrations of particular relevance in the differential diagnosis of ulcerative, nodular, or crusting skin lesions. Nonmelanoma skin cancers (NMSCs), namely, basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and also actinic keratosis (AK), are the most common malignant tumors in humans. BCCs do not proliferate rapidly and most of the times do not metastasize, while SCCs are more infiltrative, metastatic, and destructive. AKs are precursor lesions of cutaneous SCCs. The classical therapy of NMSCs makes use of photodynamic therapy associated with chemotherapeutics. With improved understanding of the pathological mechanisms of tumor initiation, progression, and differentiation, a case is made towards the use of targeted chemotherapy with the intent to reduce the cytotoxicity of classical treatments. The present review aims to describe the current state of the art on the knowledge of NMSC, including its risks factors, oncogenes, and skin carcinogenesis, discussing the classical therapy against new therapeutic options.

Cancer therapies in HIV cure research

PURPOSE OF REVIEW

This article provides an overview of anticancer therapies in various stages of clinical development as potential interventions to target HIV persistence.

RECENT FINDINGS

Epigenetic drugs developed for cancer have been investigated in vitro, ex vivo and in clinical trials as interventions aimed at reversing HIV latency and depleting the amount of virus that persists on antiretroviral therapy. Treatment with histone deacetylase inhibitors induced HIV expression in patients on antiretroviral therapy but did not reduce the frequency of infected cells. Other interventions that may accelerate the decay of latently infected cells, in the presence or absence of latency-reversing therapy, are now being explored. These include apoptosis-promoting agents, nonhistone deacetylase inhibitor compounds to reverse HIV latency and immunotherapy interventions to enhance antiviral immunity such as immune checkpoint inhibitors and Toll-like receptor agonists.

SUMMARY

A curative strategy in HIV will likely need to both reduce the amount of virus that persists on antiretroviral therapy and improve anti-HIV immune surveillance. Although we continue to explore advances in the field of oncology including cancer immunotherapy, there are major differences in the risk-benefit assessment between HIV-infected individuals and patients with malignancies. Drug development specifically targeting HIV persistence will be the key to developing effective interventions with an appropriate safety profile.

Effects of demethoxycurcumin on the viability and apoptosis of skin cancer cells

The present study investigated the effects and mechanisms of demethoxycurcumin (DMC) on a human skin squamous cell carcinoma cell line, A431, and a human keratinocyte cell line, HaCaT. A431 and HaCaT cells were cultured in vitro. The effects of DMC treatment on cell viability were analyzed using the Cell Counting kit‑8 (CCK‑8) assay; cell cycle distribution was analyzed by flow cytometry; apoptosis was assessed by flow cytometry and Hoechst 33258 staining; and the protein expression levels of cytochrome c, B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated X protein (BAX), caspase‑9 and caspase‑3 were evaluated by western blotting. CCK‑8 assay results demonstrated that DMC treatment significantly inhibited viability of A431 and HaCaT cells in a dose‑dependent manner. Flow cytometric analysis confirmed that DMC treatment induced apoptosis in a dose‑dependent manner, and significantly increased the proportion of cells in G2/M phase. Western blot analysis indicated that the protein expression levels of Bcl‑2 were decreased, whereas the expression levels of BAX, caspase‑9, caspase‑3 and cytochrome c were increased following DMC treatment compared with in untreated cells. In conclusion, DMC treatment significantly inhibited viability of A431 and HaCaT cells, and induced cell cycle arrest in G2/M phase. The present study indicated that DMC may induce apoptosis of skin cancer cells through a caspase‑dependent pathway.

Chemopreventive opportunities to control basal cell carcinoma: Current perspectives

Basal cell carcinoma (BCC) is a major health problem with approximately 2.8 million new cases diagnosed each year in the United States. BCC incidences have continued to rise due to lack of effective chemopreventive options. One of the key molecular characteristics of BCC is the sustained activation of hedgehog signaling through inactivating mutations in the tumor suppressor gene patch (Ptch) or activating mutations in Smoothened. In the past, several studies have addressed targeting the activated hedgehog pathway for the treatment and prevention of BCC, although with toxic effects. Other studies have attempted BCC chemoprevention through targeting the promotional phase of the disease especially the inflammatory component. The compounds that have been utilized in pre-clinical and/or clinical studies include green and black tea, difluoromethylornithine, thymidine dinucleotide, retinoids, non-steroidal anti-inflammatory drugs, vitamin D3, and silibinin. In this review, we have discussed genetic and epigenetic modifications that occur during BCC development as well as the current state of BCC pre-clinical and clinical chemoprevention studies.

Nonsteroidal anti-inflammatory drugs and the risk of nonmelanoma skin cancer

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been assigned a promising role in the chemoprevention of various malignancies. However, epidemiological data on the association between NSAID use and nonmelanoma skin cancer (NMSC) are limited. To explore whether patients regularly exposed to systemic NSAIDs are at a reduced risk of basal cell carcinoma (BCC) or squamous cell carcinoma (SCC), we conducted a population-based case-control analysis using the Clinical Practice Research Datalink, a United Kingdom primary care database. We identified 65,398 patients with incident BCC and 7,864 patients with incident SCC diagnosed between 1995 and 2013 and matched 1 and 4 NMSC-free controls to each BCC and SCC case, respectively, on age, sex, general practice, calendar time and years of history in the database. We compared prior NSAID exposure between cases and controls using multivariate conditional logistic regression analyses controlling for several potential confounders. Overall, we found no association between NSAID use and BCC, but when looking exclusively at users of single NSAID substances there was a suggestion of a reduced BCC risk in regular users of aspirin and ibuprofen (adjusted odds ratio [adj. OR]: 0.92, 95% confidence interval [CI]: 0.85-0.99 and adj. OR: 0.61, 95% CI: 0.48-0.78, respectively). The risk of SCC was slightly decreased in regular users of any NSAIDs (adj. OR: 0.89, 95% CI: 0.82-0.97), with the strongest risk reduction observed in current users of coxibs (adj. OR: 0.77, 95% CI: 0.62-0.95). These findings provide evidence that patients predisposed to NMSC might benefit from chemoprevention with NSAIDs.

Photodynamic therapy vs. imiquimod 5% cream as skin cancer preventive strategies in patients with field changes: a randomized intraindividual comparison study

BACKGROUND

Actinic damage is responsible for the development of multiple, recurrent non-melanoma skin cancers (NMSCs), including actinic keratoses (AKs). Photodynamic therapy (PDT) and imiquimod cream (IMIQ) 5% are recommended as field-directed treatment options.

OBJECTIVES

To compare efficacy and safety of methyl aminolevulinate (MAL)-PDT vs. IMIQ 5% in the prevention of new NMSCs development patients with field changes.

METHODS

Patients with field cancerization of the face or scalp were randomized to receive MAL-PDT on one side, and IMIQ 5% on the mirror field. The primary endpoint was the number of new lesions on the treated fields during a 12-month follow-up period. Secondary assessments included adverse events and patient preference.

RESULTS

Forty-four patients completed the study. MAL-PDT and IMIQ did not differ concerning the primary endpoint, as there was no statistically significant difference in terms of development of new NMSCs at any point of follow-up. Both treatment regimens were safe and well tolerated. Patients' preference based on the procedure, response rates and future choice favoured MAL-PDT.

CONCLUSIONS

MAL-PDT and IMIQ 5% are safe and well-tolerated treatments that equally prevent development of new AKs in patients suffering from field changes. MAL-PDT treatment appears to be superior in terms of patients' preference.

Perillyl Alcohol (Monoterpene Alcohol), Limonene

Natural products have a long history of use in traditional medicines and their activities against different diseases have been the focus of many basic and clinical researches in past few decades. The essential oils, volatile liquid containing aroma compound from plants, are known as active ingredients in the herbal medicine. Perillyl alcohol (POH) is usually available through dietary sources and is being explored for its cancer chemoprevention, tumor growth suppression, and regression. Citrus peels are the waste product of juice manufacturing industries and have been considered as a critical problem for environmental green ecology policies for years. One of the most well-known approaches to overcome this problem is transformation of these monoterpene by the use of specific strains of bacteria or yeasts. Limonene (1-methyl-4-isopropyl-cyclohexene) is a monoterpene, as other monoterpenes consists of two isoprene units, that comprises more than 90% of citrus essential oil and it exists in many fruits and vegetables. Although, the anticancer activity of d-limonene has identified nearly two decades ago, it has recently attracted much more attention in translational medicine. In this chapter, we will overview the anticancer effects of POH and d-limonene. Later, we will address the pharmacokinetics of these compounds, highlight the signaling pathways which are targeted by these proteins, review the clinical trials which have been done for these compounds in different cancer models, and finally discuss the future directions of the research in this field that might be more applicable in future cancer therapy strategies.

Etiology and pathogenesis of basal cell carcinoma

Basal cell carcinoma (BCC) is the most common cancer among Caucasians. It generally occurs on sun-exposed areas of the body, mostly on the head and neck (80%), trunk (15%), rarely on arms and legs. Basal cell carcinoma is a good example of a disease caused by a combination of genetic and environmental factors. Ultraviolet (UV) radiation plays a dual role in the development of BCC: it causes DNA damage and immunosuppression. UVA and UVB rays damage the DNA via various mechanisms. UVB radiation directly damages DNA within skin cells, causing cytosine → thymine mutations at dipyrimidine sites, whereas UVA radiation is 10.000 times less mutagenic, but it is significantly more present in the natural UV radiation. Also, UVA photons have lower energy than UVB photons and do not induce mutations. UV radiation exerts immune suppression by decreasing the antigen presenting cells ability and by producing immunosuppressive cytokines, such as interleukin-10 (IL-10) and tumor necrosis factor alpha (TNF-α). Mediators of UV-induced immunosuppression are DNA and cis-urocanic acid. Several studies showed a significant association between the development of BCC and sun-exposure during childhood and adolescence, and a strong relation with family history of skin cancer. Exposure to ionizing radiation increases the risk of nonmelanoma skin cancers by three times, while the risk is proportional to the radiation dose. Chemical carcinogens, such as arsenic, tar, psoralen, and pesticides, increase risks for nonmelanoma skin cancers, predominantly for squamous cell carcinoma (SCC). Regarding genetic predisposition, there is glutathione S-transferase (GST) as an important part of cellular defense against endogenous and exogenous chemicals. Several polymorphisms in GST family members have been associated with impaired detoxification, thus influencing the risk for some cancers, including nonmelanoma skin cancers. Cytochrome P450 enzymes are involved in detoxification of photosensitizing agents, and thus involved in BCC carcinogenesis. PTCH is a tumor suppressor gene first identified in patients with Gorlin syndrome. Abnormal activation of this gene and its pathways result in various types of tumorigenesis. BCC is associated with homozygous PTCH gene deletion. With regard to acquired genetic mutations, it was found that aggressive BCCs are significantly associated with increased p53 protein expression, probably representing the mutated form, although that assertion could not be established with certainty. Considering the apparently limited contribution of DNA damage and chromosome instability to the expression of BCC phenotype, the relevance of p53 mutations for BCC growth remains to be demonstrated. Data on the role of Bcl-2 gene family in the development of BCC are scarce. It is unclear whether Bcl-2 has a functional role in the development of BCC, or it only indicates the level of gene expression in tumor stem cells. Activation of Ras gene may play an important role during early stages in the development of nonmelanoma skin cancers, and it is often found on UV-exposed skin in BCC, actinic keratosis and SCC. Concerning immunologic factors, studies have shown that tumor necrosis factor-α (TNF-α) is the critical mast cell product involved in ultraviolet-induced immunosuppression: mast cells contain high quantities of TNF-α which is released after activation; the level of TNF-α is increased in the skin exposed to UV radiation disrupting the morphology and function of Langerhans cells, the principal antigen-presenting cells of the skin. An animal study suggests that the degree of susceptibility to ultraviolet-B-induced local immunosuppression depends on TNF-α level within the epidermis after UVB. It has been established that mast cell-derived histamine stimulates prostaglandin E2 (PGE2) production from keratinocytes. PGE2 alters the cytokine balance in favor of the immunosuppressive interleukin-10 (IL-10) against the immunostimulatory IL-12; histamine also increases suppressor T-cell function by binding to the H2 receptors, which in turn release higher levels of immune suppressive cytokines including IL-10 and induce apoptosis of antigen-presenting cells. All this results in a shift of the immune response from T helper 1 (Th1) cytokine profile to T helper 2 (Th2) cytokine profile, inhibiting antigen-presenting cells to induce antitumor activity.

The preventive role of breadfruit against inflammation-associated epithelial carcinogenesis in mice

Artocarpus communis has been identified as a rich source of flavonoids and has been gaining attention for its potential chemopreventive abilities. In this study, methanol extracts from the fruit of A. communis (MEFA) and leaf of A. communis (MELA) were prepared, and their effects on inflammation-associated skin tumorigenesis were assessed using mouse models, including 12-O-tetradecanoylphorbol-13-acetate (TPA) induced cutaneous inflammation as well as 7,12-dimethylbenz[α]anthracene (DMBA) initiated and TPA-promoted skin tumorigenesis. According to the results, both MEFA and MELA decreased the intensity of leukocyte infiltration in mouse dorsal skin and cutaneous edema induced by TPA, which appeared to be mediated by inhibition of proinflammatory genes (inducible nitric oxide synthase, cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), IL-1β, and IL-6) and proinflammatory mediators (TNF-α, IL-1β, and Prostaglandin E2 ). In addition, topical application with MEFA or MELA effectively attenuated tumor incidence, multiplicity, volume, malignancy as well as angiogenesis of TPA-stimulated skin tumor promotion in DMBA-initiated mice. Notably, immunohistochemical stain showed that MEFA and MELA attenuated COX-2 expression of both skin and tumor tissues in different animal tests, which may be closely related to the suppression of nuclear factor kappa B/activator protein signaling networks. These findings first demonstrate that flavonoid-rich A. communis may exert potent anti-inflammatory activity through modulation of COX-2 in TPA-activated skin and tumor tissues.

Topical treatment with diclofenac, calcipotriol (vitamin-D3 analog) and difluoromethylornithine (DFMO) does not prevent nonmelanoma skin cancer in mice

Nonmelanoma skin cancer is a common cancer type with increasing incidence. The purpose of this study was to evaluate topical application of diclofenac, calcipotriol, and difluoromethylornithine as chemoprevention in a mouse model of ultraviolet light-induced skin tumors, since these agents have been reported to have tumor inhibiting properties. One hundred twenty eight mice were treated with UVB radiation followed by chemoprevention or placebo. There were no significant effects of the treatments with respect to presence of skin tumors, number of tumors, tumor size, or survival. The investigated drugs were ineffective as chemoprevention in the dose regimens used in this study.

Fibroblast senescence and squamous cell carcinoma: how wounding therapies could be protective

BACKGROUND

Squamous cell carcinoma (SCC), which has one of the highest incidences of all cancers in the United States, is an age-dependent disease, with the majority of these cancers diagnosed in people age 70 and older. Recent findings have led to a new hypothesis on the pathogenesis of SCC.

OBJECTIVES

To evaluate the potential of preventive therapies to reduce the incidence of SCC in at-risk geriatric patients.

MATERIALS AND METHODS

Survey of current literature on wounding therapies to prevent SCCs.

RESULTS

This new hypothesis of SCC photocarcinogenesis states that senescent fibroblasts accumulate in the dermis, resulting in a reduction in dermal insulin-like growth factor-1 (IGF-1) expression. This lack of IGF-1 expression sensitizes epidermal keratinocytes to fail to suppress ultraviolet light B (UVB)-induced mutations, leading to increased proclivity to photocarcinogenesis. Recent evidence suggests that dermal wounding therapies, specifically dermabrasion and fractionated laser resurfacing, can decrease the proportion of senescent dermal fibroblasts, increase dermal IGF-1 expression, and correct the inappropriate UVB response found in geriatric skin, protecting geriatric keratinocytes from UVB-induced SCC initiation.

CONCLUSIONS

In this review, we will discuss the translation of pioneering basic science results implicating commonly used dermal fibroblast rejuvenation procedures as preventative treatments for SCC.

Nonmelanoma skin cancer of the head and neck: prevention

The importance and effectiveness of prevention efforts and strategies for skin cancers are reviewed. Topical sunscreens and their proper use are presented. Topical and ingested forms of natural, synthetic, or biologic chemical agents that are potentially efficacious for chemoprevention are listtdldted and discussed.

Basal Cell Carcinoma: A Frequent Challenge / Bazocelularni karcinom: čest izazov

Basal cell carcinoma is a slow-growing, malignant epidermal tumor predominantly affecting sun exposed areas in Caucasians, accounting for up to 80% of all diagnosed skin cancers, with a rising incidence. Chronic UV radiation, in association with constitutional factors, plays the main role in its etiology. Inappropriate activation of the hedgehog signaling pathway seems to be a key pathogenesis mechanism. Basal cell carcinoma metastases are extremely rare, but it is a locally invasive tumor that can cause significant destruction of the surrounding tissues, with their functional and esthetic impairment. There are four main clinical types of basal cell carcinoma, although clinical classification is of poor prognostic significance. Preselection of suspicious lesions and treatment planning include noninvasive diagnostic techniques: dermoscopy, confocal microscopy and ultrasoud imaging, yet histopathology remains the “gold standard” of basal cell carcinoma diagnosis. In terms of the histological growth pattern, which is essential for the prognosis, basal cell carcinoma may be divided into circumscribed or diffuse types. Surgical excision is considered to be a first line treatment option, but there are numerous less invasive treatment modalities for low-risk basal cell carcinoma. Prevention strategies are focused on behavioral modifications, regular follow up and use of chemopreventive agents in high-risk patients.