Peter G. Parsons

Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomised controlled trial

BACKGROUND The use of sunscreens on the skin can prevent sunburn but whether long-term use can prevent skin cancer is not known. Also, there is evidence that oral betacarotene supplementation lowers skin-cancer rates in animals, but there is limited evidence of its effect in human beings. METHODS In a community-based randomised trial with a 2 by 2 factorial design, individuals were assigned to four treatment groups: daily application of a sun protection factor 15-plus sunscreen to the head, neck, arms, and hands, and betacarotene supplementation (30 mg per day); sunscreen plus placebo tablets; betacarotene only; or placebo only. Participants were 1621 residents of Nambour in southeast Queensland, Australia. The endpoints after 4.5 years of follow-up were the incidence of basal-cell and squamous-cell carcinomas both in terms of people treated for newly diagnosed disease and in terms of the numbers of tumours that occurred. Analysis of the effect of sunscreen was based only on skin cancers that developed on sites of daily application. All analyses were by intention to treat. FINDINGS 1383 participants underwent full skin examination by a dermatologist in the follow-up period. 250 of them developed 758 new skin cancers during the follow-up period. There were no significant differences in the incidence of first new skin cancers between groups randomly assigned daily sunscreen and no daily sunscreen (basal-cell carcinoma 2588 vs 2509 per 100,000; rate ratio 1.03 [95% CI 0.73-1.46]; squamous-cell carcinoma 876 vs 996 per 100,000; rate ratio 0.88 [0.50-1.56]). Similarly, there was no significant difference between the betacarotene and placebo groups in incidence of either cancer (basal-cell carcinoma 3954 vs 3806 per 100,000; 1.04 [0.73-1.27]; squamous-cell carcinoma 1508 vs 1146 per 100,000; 1.35 [0.84-2.19]). In terms of the number of tumours, there was no effect on incidence of basal-cell carcinoma by sunscreen use or by betacarotene but the incidence of squamous-cell carcinoma was significantly lower in the sunscreen group than in the no daily sunscreen group (1115 vs 1832 per 100,000; 0.61 [0.46-0.81]). INTERPRETATION There was no harmful effect of daily use of sunscreen in this medium-term study. Cutaneous squamous-cell carcinoma, but not basal-cell carcinoma seems to be amenable to prevention through the routine use of sunscreen by adults for 4.5 years. There was no beneficial or harmful effect on the rates of either type of skin cancer, as a result of betacarotene supplementation.

Antitumor Activity of 3-Ingenyl Angelate: Plasma Membrane and Mitochondrial Disruption and Necrotic Cell Death

Options for skin cancer treatment currently include surgery, radiotherapy, topical chemotherapy, cryosurgery, curettage, and electrodessication. Although effective, surgery is costly and unsuitable for certain patients. Radiotherapy can leave a poor cosmetic effect, and current chemotherapy is limited by low cure rates and extended treatment schedules. Here, we describe the preclinical activity of a novel topical chemotherapeutic agent for the treatment of skin cancer, 3-ingenyl angelate (PEP005), a hydrophobic diterpene ester isolated from the plant Euphorbia peplus. Three daily topical applications of 42 nmol (18 micro g) of PEP005 cured a series of s.c. mouse tumors (B16 melanoma, LK2 UV-induced squamous cell carcinoma, and Lewis lung carcinoma; n = >14 tumors/group) and human tumors (DO4 melanoma, HeLa cervical carcinoma, and PC3 and DU145 prostate carcinoma; n = >4 tumors/group) previously established (5-10 mm(3)) on C57BL/6 or Foxn1(nu) mice. The treatment produced a mild, short-term erythema and eschar formation but, ultimately, resulted in excellent skin cosmesis. The LD(90) for PEP005 for a panel of tumor cell lines was 180-220 micro M. Electron microscopy showed that treatment with PEP005 both in vitro (230 micro M) and in vivo (42 nmol) rapidly caused swelling of mitochondria and cell death by primary necrosis. (51)Cr release, uptake of propidium iodide, and staining with the mitochondria dye JC1, revealed that PEP005 (230 micro M) treatment of tumor cells in vitro resulted in a rapid plasma membrane perturbation and loss of mitochondrial membrane potential. PEP005 thus emerges as a new topical anti-skin cancer agent that has a novel mode of action involving plasma membrane and mitochondrial disruption and primary necrosis, ultimately resulting in an excellent cosmetic outcome.

Head and neck cancer: past, present and future

Head and neck cancer consists of a diverse group of cancers that ranges from cutaneous, lip, salivary glands, sinuses, oral cavity, pharynx and larynx. Each group dictates different management. In this review, the primary focus is on head and neck squamous cell carcinoma (HNSCC) arising from the mucosal lining of the oral cavity and pharynx, excluding nasopharyngeal cancer. Presently, HNSCC is the sixth most prevalent neoplasm in the world, with approximately 900,000 cases diagnosed worldwide. Prognosis has improved little in the past 30 years. In those who have survived, pain, disfigurement and physical disability from treatment have had an enormous psychosocial impact on their lives. Management of these patients remains a challenge, especially in developing countries where this disease is most common. Of all human cancers, HNSCC is the most distressing since the head and neck is the site of the most complex functional anatomy in the human body. Its areas of responsibility include breathing, the CNS, vision, hearing, balance, olfaction, taste, swallowing, voice, endocrine and cosmesis. Cancers that occur in this area impact on these important human functions. Consequently, in treating cancers of the head and neck, the effects of the treatment on the functional outcome of the patient need the most serious consideration. In assessing the success of HNSCC treatment, consideration of both the survival and functional deficits that the patient may suffer as a consequence of their treatment are of paramount importance. For this reason, the modern-day management of head and neck patients should be carried out in a multidisciplinary head and neck clinic.

Characterization of the Melanoma miRNAome by Deep Sequencing.

Background MicroRNAs (miRNAs) are 18–23 nucleotide non-coding RNAs that regulate gene expression in a sequence specific manner. Little is known about the repertoire and function of miRNAs in melanoma or the melanocytic lineage. We therefore undertook a comprehensive analysis of the miRNAome in a diverse range of pigment cells including: melanoblasts, melanocytes, congenital nevocytes, acral, mucosal, cutaneous and uveal melanoma cells. Methodology/Principal Findings We sequenced 12 small RNA libraries using Illuminas Genome Analyzer II platform. This massively parallel sequencing approach of a diverse set of melanoma and pigment cell libraries revealed a total of 539 known mature and mature-star sequences, along with the prediction of 279 novel miRNA candidates, of which 109 were common to 2 or more libraries and 3 were present in all libraries. Conclusions/Significance Some of the novel candidate miRNAs may be specific to the melanocytic lineage and as such could be used as biomarkers to assist in the early detection of distant metastases by measuring the circulating levels in blood. Follow up studies of the functional roles of these pigment cell miRNAs and the identification of the targets should shed further light on the development and progression of melanoma.

Neutrophils are a key component of the antitumor efficacy of topical chemotherapy with ingenol-3-angelate.

Harnessing neutrophils for the eradication of cancer cells remains an attractive but still controversial notion. In this study, we provide evidence that neutrophils are required to prevent relapse of skin tumors following topical treatment with a new anticancer agent, ingenol-3-angelate (PEP005). Topical PEP005 treatment induces primary necrosis of tumor cells, potently activates protein kinase C, and was associated with an acute T cell-independent inflammatory response characterized by a pronounced neutrophil infiltrate. In Foxn1nu mice depleted of neutrophils and in CD18-deficient mice (in which neutrophil extravasation is severely impaired) PEP005 treatment was associated with a >70% increase in tumor relapse rates. NK cell or monocyte/macrophage deficiency had no effect on relapse rates. Both in vitro and in mice, PEP005 induced MIP-2/IL-8, TNF-α, and IL-1β, all mediators of neutrophil recruitment and activation. In vitro, PEP005 activated human endothelial cells resulting in neutrophil adhesion and also induced human neutrophils to generate tumoricidal-reactive oxygen intermediates. Treatment of tumors with PEP005 significantly elevated the level of anticancer Abs, which were able to promote neutrophil-mediated Ab-dependent cellular cytotoxicity (ADCC) in vitro. PEP005 treatment of tumors grown in SCID mice was also associated with >70% increase in tumor relapse rates. Taken together, these data suggest a central role for neutrophil-mediated ADCC in preventing relapse. PEP005-mediated cure of tumors therefore appears to involve initial chemoablation followed by a neutrophil-dependent ADCC-mediated eradication of residual disease, illustrating that neutrophils can be induced to mediate important anticancer activity with specific chemotherapeutic agents.

p53 expression and risk factors for cutaneous melanoma: A case‐control study

Epidemiological data strongly implicate sunlight as the principal environmental cause of melanoma; however, critical molecular targets for ultraviolet (UV)‐induced melanoma remain to be identified. The p53 tumor suppressor gene is one possible target, being abnormally expressed in 20–40% of primary melanomas. We undertook a population‐based molecular epidemiological study with the aim of determining the environmental and phenotypic factors associated with p53‐positive and p53‐negative melanomas. One hundred fifty cases of melanoma were randomly ascertained from the Queensland Cancer Registry and matched to 150 electoral roll controls. Data on environmental and phenotypic exposures were collected through interviews and physical examination of all participants. Sections of tumor tissue were obtained from 134 (89%) cases and stained with the anti‐p53 DO‐7 monoclonal antibody (MAb) following microwave antigen retrieval. Of 121 useable sections, 22 tumors (18%) had more than 1% cells with positive staining consistent with abnormalities in p53 expression. Strongest predictors of p53‐positive melanoma were inability to tan [odds ratio (OR) 6.8], history of non‐melanoma skin cancer (OR 3.2) and site of melanoma: head/neck (OR 2.2) and lower limbs (OR 2.3). In contrast, factors such as nevus density and freckling propensity were strongly associated only with p53‐immunonegative melanoma (OR 8.6 for >25 moles; OR 3.0 for heavy facial freckling). Overall, the determinants of p53‐positive and p53‐negative melanomas were independent and complementary, the former being associated with features of sun‐sensitivity and chronic sun exposure, the latter with phenotypic markers of melanocytic proliferation. Our findings are consistent with at least 2 independent pathways in the pathogenesis of melanoma, characterized by environmental induction and p53 overexpression on the one hand and pigment cell instability on the other. Int. J. Cancer 77:843–848, 1998.© 1998 Wiley‐Liss, Inc.

Anti-malarial effect of histone deacetylation inhibitors and mammalian tumour cytodifferentiating agents.

The histones of Plasmodium falciparum represent a potential new target for anti-malarial compounds. A naturally occurring compound, apicidin, has recently been shown to inhibit the in vitro growth of P. falciparum. Apicidin was shown to hyperacetylate histones, suggesting that its mode of action is through histone deacetylase inhibition. We have tested the ability of known histone deacetylase inhibitors, mammalian tumour suppressor compounds, and cytodifferentiating agents to inhibit the in vitro growth of a drug sensitive and resistant strain of P. falciparum. Seven of the tested compounds had microM IC50 values, and trichostatin A, a histone deacetylation inhibitor and cytodifferentiating agent, was active at low nM concentrations. One compound, suberic acid bisdimethylamide, which selectively arrests tumour cells as opposed to normal mammalian cells, had an in vivo cytostatic effect against the acute murine malaria Plasmodium berghei, and one round of treatment with the compound failed to select for resistant mutations. These results suggest a promising role for histone deacetylase inhibitors and cytodifferentiating agents as antimalarial drug candidates.

Anti-tumour activity in vitro and in vivo of selective differentiating agents containing hydroxamate.

SummaryA series of hydroxamates, which are not metalloprotease inhibitors, have been found to be selectively toxic to a range of transformed and human tumour cells without killing normal cells (fibroblasts, melanocytes) at the same concentrations. Within 24 h of treatment, drug action is characterized by morphological reversion of tumour cells to a more normal phenotype (dendritic morphology), and rapid and reversible acetylation of histone H4 in both tumour and normal cells. Two hydroxamates inhibited growth of xenografts of human melanoma cells in nude mice; resistance did not develop in vivo or in vitro. A third hydroxamate, trichostatin A, was active in vitro but became inactivated and had no anti-tumour activity in vivo. Development of dendritic morphology was found to be dependent upon phosphatase activity, RNA and protein synthesis. Proliferating hybrid clones of sensitive and resistant cells remained sensitive to ABHA, indicating a dominant-negative mechanism of sensitivity. Histone H4 hyperacetylation suggests that these agents act at the chromatin level. This work may lead to new drugs that are potent, and selective anti-tumour agents with low toxicity to normal cells.

Novel markers for poor prognosis in head and neck cancer.

Head and neck cancer (HNSCC) is one of the most distressing human cancers, causing pain and affecting the basic survival functions of breathing and swallowing. Mortality rates have not changed despite recent advances in radiotherapy and surgical treatment. We have compared the expression of over 13,000 unique genes in 7 cases of matched HNSCC and normal oral mucosa. Of the 1,260 genes that showed statistically significant differences in expression between normal and tumor tissue at the mRNA level, the three top ranking of the top 5% were selected for further analysis by immunohistochemistry on paraffin sections, along with the tumor suppressor genes p16 and p53, in a total of 62 patients including 55 for whom >4‐year clinical data was available. Using univariate and multivariate survival analysis, we identified SPARC/osteonectin as a powerful independent prognostic marker for short disease‐free interval (DFI) (p < 0.002) and poor overall survival (OS) (p = 0.018) of HNSCC patients. In combination with other ECM proteins found in our analysis, PAI‐1 and uPA, the association with DFI and OS became even more significant (p < 0.001). Our study represents the first instance of SPARC as an independent prognostic marker in HNSCC.

A case report: Immune responses and clinical course of the first human use of granulocyte/macrophage-colony-stimulating-factor-transduced autologous melanoma cells for immunotherapy

Abstract The first use of granulocyte/macrophage-colony-stimulating-factor-transduced, lethally irradiated, autologous melanoma cells as a therapeutic vaccine in a patient with rapidly progressive, widely disseminated malignant melanoma resulted in the generation of a novel antitumour immune response associated with partial, albeit temporary, clinical benefit. An initially negative reaction to non-transduced, autologous melanoma cells was converted to a delayed-type hypersensitivity (DTH) reaction of increasing magnitude following successive vaccinations. While intradermal vaccine sites showed prominent dendritic cell accrual, DTH sites revealed a striking influx of eosinophils in addition to activated/memory T lymphocytes and macrophages, recalling the histology of challenge tumour cell rejection in immune mice. Cytotoxic T lymphocytes (CTL) reactive with autologous melanoma cells were detectable at high frequency after vaccination, not only in limiting-dilution analysis, but also in bulk culture without added cytokines. Clonal analysis of CTL showed a conversion from a purely CD8+ response to a high proportion of CD4+ clones following vaccination. A prominent acute-phase response manifested by a five- to tenfold increase in C-reactive protein was observed, as was a systemic eosinophilia. Vaccination resulted in the regression of axillary lymphatic metastases, stabilisation of pulmonary metastases, and a dramatic, reversible increase in cerebral oedema associated with multiple central nervous system metastases; however, lesions in the adrenal glands, pancreas and spleen proved refractory. The antitumour effects and immune response were not detectable 2 months following the last vaccination. Irradiation of the extensive cerebral metastases resulted in rapid deterioration and death of the patient.