Lipoxygenase metabolism : roles in tumor progression and survival

The metabolism of arachidonic acid through lipoxygenase pathways leads to the generation of various biologically active eicosanoids. The expression of these enzymes vary throughout the progression of various cancers, and thereby they have been shown to regulate aspects of tumor development. Substantial evidence supports a functional role for lipoxygenase-catalyzed arachidonic and linoleic acid metabolism in cancer development. Pharmacologic and natural inhibitors of lipoxygenases have been shown to suppress carcinogenesis and tumor growth in a number of experimental models. Signaling of hydro[peroxy]fatty acids following arachidonic or linoleic acid metabolism potentially effect diverse biological phenomenon regulating processes such as cell growth, cell survival, angiogenesis, cell invasion, metastatic potential and immunomodulation. However, the effects of distinct LOX isoforms differ considerably with respect to their effects on both the individual mechanisms described and the tumor being examined. 5-LOX and platelet type 12-LOX are generally considered pro-carcinogenic, with the role of 15-LOX-1 remaining controversial, while 15-LOX-2 suppresses carcinogenesis. In this review, we focus on the molecular mechanisms regulated by LOX metabolism in some of the major cancers. We discuss the effects of LOXs on tumor cell proliferation, their roles in cell cycle control and cell death induction, effects on angiogenesis, migration and the immune response, as well as the signal transduction pathways involved in these processes. Understanding the molecular mechanisms underlying the anti-tumor effect of specific, or general, LOX inhibitors may lead to the design of biologically and pharmacologically targeted therapeutic strategies inhibiting LOX isoforms and/or their biologically active metabolites, that may ultimately prove useful in the treatment of cancer, either alone or in combination with conventional therapies. © 2007 Springer Science+Business Media, LLC.

Prognostic value of TP53, KRAS and EGFR mutations in nonsmall cell lung cancer : the EUELC cohort

Nonsmall cell lung cancer samples from the European Early Lung Cancer biobank were analysed to assess the prognostic significance of mutations in the TP53, KRAS and EGFR genes. The series included 11 never-smokers, 86 former smokers, 152 current smokers and one patient without informed smoking status. There were 110 squamous cell carcinomas (SCCs), 133 adenocarcinomas (ADCs) and seven large cell carcinomas or mixed histologies. Expression of p53 was analysed by immunohistochemistry. DNA was extracted from frozen tumour tissues. TP53 mutations were detected in 48.8% of cases and were more frequent among SCCs than ADCs (p<0.0001). TP53 mutation status was not associated with prognosis. G to T transversions, known to be associated with smoking, were marginally more common among patients who developed a second primary lung cancer or recurrence/metastasis (progressive disease). EGFR mutations were almost exclusively found in never-smoking females (p=0.0067). KRAS mutations were detected in 18.5% of cases, mainly ADC (p<0.0001), and showed a tendency toward association with progressive disease status. These results suggest that mutations are good markers of different aetiologies and histopathological forms of lung cancers but have little prognostic value, with the exception of KRAS mutation, which may have a prognostic value in ADC. Copyright©ERS 2012.

Crizotinib versus chemotherapy in advanced ALK-positive lung cancer

BACKGROUND: In single-group studies, chromosomal rearrangements of the anaplastic lymphoma kinase gene (ALK ) have been associated with marked clinical responses to crizotinib, an oral tyrosine kinase inhibitor targeting ALK. Whether crizotinib is superior to standard chemotherapy with respect to efficacy is unknown. METHODS: We conducted a phase 3, open-label trial comparing crizotinib with chemotherapy in 347 patients with locally advanced or metastatic ALK-positive lung cancer who had received one prior platinum-based regimen. Patients were randomly assigned to receive oral treatment with crizotinib (250 mg) twice daily or intravenous chemotherapy with either pemetrexed (500 mg per square meter of body-surface area) or docetaxel (75 mg per square meter) every 3 weeks. Patients in the chemotherapy group who had disease progression were permitted to cross over to crizotinib as part of a separate study. The primary end point was progression-free survival. RESULTS: The median progression-free survival was 7.7 months in the crizotinib group and 3.0 months in the chemotherapy group (hazard ratio for progression or death with crizotinib, 0.49; 95% confidence interval [CI], 0.37 to 0.64; P<0.001). The response rates were 65% (95% CI, 58 to 72) with crizotinib, as compared with 20% (95% CI, 14 to 26) with chemotherapy (P<0.001). An interim analysis of overall survival showed no significant improvement with crizotinib as compared with chemotherapy (hazard ratio for death in the crizotinib group, 1.02; 95% CI, 0.68 to 1.54; P=0.54). Common adverse events associated with crizotinib were visual disorder, gastrointestinal side effects, and elevated liver aminotransferase levels, whereas common adverse events with chemotherapy were fatigue, alopecia, and dyspnea. Patients reported greater reductions in symptoms of lung cancer and greater improvement in global quality of life with crizotinib than with chemotherapy. CONCLUSIONS: Crizotinib is superior to standard chemotherapy in patients with previously treated, advanced non-small-cell lung cancer with ALK rearrangement. (Funded by Pfizer; ClinicalTrials.gov number, NCT00932893.) Copyright © 2013 Massachusetts Medical Society.

Characterisation of a human skin equivalent model to study the effects of ultraviolet B radiation on keratinocytes

The incidences of skin cancers resulting from chronic ultraviolet radiation (UVR) exposure are on the incline both in Australia and globally. Hence, the cellular and molecular pathways associated with UVR-induced photocarcinogenesis urgently need to be elucidated, in order to develop more robust preventative and treatment strategies against skin cancers. In vitro investigations into the effects of UVR (in particular the highly-mutagenic UVB wavelength) have, to date, mainly involved the use of cell culture and animal models. However, these models possess biological disparities to native skin, which to some extent have limited their relevance to the in vivo situation. To address this, we characterised a 3-dimensional, tissue-engineered human skin equivalent (HSE) model (consisting of primary human keratinocytes cultured on a dermal-derived scaffold) as a representation of a more physiologically-relevant platform to study keratinocyte responses to UVB. Significantly, we demonstrate that this model retains several important epidermal properties of native skin. Moreover, UVB-irradiation of the HSE constructs was shown to induce key markers of photodamage in the HSE keratinocytes, including the formation of cyclobutane pyrimidine dimers, the activation of apoptotic pathways, the accumulation of p53 and the secretion of inflammatory cytokines. Importantly, we also demonstrate that the UVB-exposed HSE constructs retain the capacity for epidermal repair and regeneration following photodamage. Together, our results demonstrate the potential of this skin equivalent model as a tool to study various aspects of the acute responses of human keratinocytes to UVB radiation damage.

A qualitative exploration of sun safety beliefs among Australian adults

Informed broadly by the theory of planned behaviour, this study used qualitative methodology to understand Australian adults' sun-protective decisions. Forty-two adults participated in focus groups where they discussed behavioural (advantages and disadvantages), normative (important referents), and control (barriers and facilitators) beliefs, as well as potential social influences and images of tanned and non-tanned people. Responses were analysed using the consensual qualitative research approach to determine the dominant themes. Themes of fashion and comfort were prominent, the important role of friends and family in sun safe decision-making was highlighted, as was the availability of sun-protective measures (e.g., in an accessible place or in the environment). Additional themes included the need to model sound sun-protective behaviours to (current and future) children, the emphasis on personal choice and personal responsibility to be sun safe, and the influence of Australian identity and culture on tanning and socially acceptable forms of sun protection. These beliefs can be used to inform interventions and public health campaigns targeting sun safety among Australians, a population with the highest skin cancer incidence in the world.

BRAF inhibitor therapy for melanoma, thyroid and colorectal cancers : development of resistance and future prospects

BRAF is a major oncoprotein and oncogenic mutations in BRAF are found in a significant number of cancers, including melanoma, thyroid cancer, colorectal cancer and others. Consequently, BRAF inhibitors have been developed as treatment options for cancers with BRAF mutations which have shown some success in improving patient outcomes in clinical trials. Development of resistance to BRAF kinase inhibitors is common, however, and overcoming this resistance is an area of significant concern for clinicians, patients and researchers alike. In this review, we identify the mechanisms of BRAF kinase inhibitor resistance and discuss the implications for strategies to overcome this resistance in the context of new approaches such as multi-kinase targeted therapies and emerging RNA interference based technologies.

B-Raf mutation : a key player in molecular biology of cancer

B-Raf is one of the more commonly mutated proto-oncogenes implicated in the development of cancers. In this review, we consider the mechanisms and clinical impacts of B-Raf mutations in cancer and discuss the implications for the patient in melanoma, thyroid cancer and colorectal cancer, where B-Raf mutations are particularly common.

Second skin : fashion design education to enhance sun safety awareness toolkit

A toolkit designed to facilitate greater understanding of the role of fashion design in society and the value of design thinking skills in solving wicked challenges. The program uses fashion as a catalyst to provide a framework for young people to address a systemic health issue (skin cancer), and in doing so, obtain a more acute awareness of the sun safety message (alternative to a scare campaign.

Multiple primary cancers associated with Merkel cell carcinoma in Queensland, Australia, 1982-2011

The relatively high incidence of Merkel cell carcinoma (MCC) in Queensland provides a valuable opportunity to examine links with other cancers. A retrospective cohort study was performed using data from the Queensland Cancer Registry. Standardized incidence ratios (SIRs) were used to approximate the relative risk of being diagnosed with another primary cancer either following or prior to MCC. Patients with an eligible first primary MCC (n=787) had more than double the expected number of subsequent primary cancers (SIR=2.19, 95% confidence interval (CI)=1.84–2.60; P<0.001). Conversely, people who were initially diagnosed with cancers other than MCC were about two and a half times more likely to have a subsequent primary MCC (n=244) compared with the general population (SIR=2.69, 95% CI=2.36–3.05; P<0.001). Significantly increased bi-directional relative risks were found for melanoma, lip cancer, head and neck cancer, lung cancer, myelodysplastic diseases, and cancer with unknown primary site. In addition, risks were elevated for female breast cancer and kidney cancer following a first primary MCC, and for subsequent MCCs following first primary colorectal cancer, prostate cancer, non-Hodgkin lymphoma, or lymphoid leukemia. These results suggest that several shared pathways are likely for MCC and other cancers, including immunosuppression, UV radiation, and genetics.

Evaluation of a skin self examination attitude scale using an item response theory model approach

Introduction The Skin Self-Examination Attitude Scale (SSEAS) is a brief measure that allows for the assessment of attitudes in relation to skin self-examination. This study evaluated the psychometric properties of the SSEAS using Item Response Theory (IRT) methods in a large sample of men ≥ 50 years in Queensland, Australia. Methods A sample of 831 men (420 intervention and 411 control) completed a telephone assessment at the 13-month follow-up of a randomized-controlled trial of a video-based intervention to improve skin self-examination (SSE) behaviour. Descriptive statistics (mean, standard deviation, item–total correlations, and Cronbach’s alpha) were compiled and difficulty parameters were computed with Winsteps using the polytomous Rasch Rating Scale Model (RRSM). An item person (Wright) map of the SSEAS was examined for content coverage and item targeting. Results The SSEAS have good psychometric properties including good internal consistency (Cronbach’s alpha = 0.80), fit with the model and no evidence for differential item functioning (DIF) due to experimental trial grouping was detected. Conclusions The present study confirms the SSEA scale as a brief, useful and reliable tool for assessing attitudes towards skin self-examination in a population of men 50 years or older in Queensland, Australia. The 8-item scale shows unidimensionality, allowing levels of SSE attitude, and the item difficulties, to be ranked on a single continuous scale. In terms of clinical practice, it is very important to assess skin cancer self-examination attitude to identify people who may need a more extensive intervention to allow early detection of skin cancer.

Cancer survivors at work : Work-related problems and factors associated with their employment, work ability and social support from the work community

Due to the improved prognosis of many forms of cancer, an increasing number of cancer survivors are willing to return to work after their treatment. It is generally believed, however, that people with cancer are either unemployed, stay at home, or retire more often than people without cancer. This study investigated the problems that cancer survivors experience on the labour market, as well as the disease-related, sociodemographic and psychosocial factors at work that are associated with the employment and work ability of cancer survivors. The impact of cancer on employment was studied combining the data of Finnish Cancer Registry and census data of the years 1985, 1990, 1995 or 1997 of Statistics Finland. There were two data sets containing 46 312 and 12 542 people with cancer. The results showed that cancer survivors were slightly less often employed than their referents. Two to three years after the diagnosis the employment rate of the cancer survivors was 9% lower than that of their referents (64% vs. 73%), whereas the employment rate was the same before the diagnosis (78%). The employment rate varied greatly according to the cancer type and education. The probability of being employed was greater in the lower than in the higher educational groups. People with cancer were less often employed than people without cancer mainly because of their higher retirement rate (34% vs. 27%). As well as employment, retirement varied by cancer type. The risk of retirement was twofold for people having cancer of the nervous system or people with leukaemia compared to their referents, whereas people with skin cancer, for example, did not have an increased risk of retirement. The aim of the questionnaire study was to investigate whether the work ability of cancer survivors differs from that of people without cancer and whether cancer had impaired their work ability. There were 591 cancer survivors and 757 referents in the data. Even though current work ability of cancer survivors did not differ between the survivors and their referents, 26% of cancer survivors reported that their physical work ability, and 19% that their mental work ability had deteriorated due to cancer. The survivors who had other diseases or had had chemotherapy, most often reported impaired work ability, whereas survivors with a strong commitment to their work organization, or a good social climate at work, reported impairment less frequently. The aim of the other questionnaire study containing 640 people with the history of cancer was to examine extent of social support that cancer survivors needed, and had received from their work community. The cancer survivors had received most support from their co-workers, and they hoped for more support especially from the occupational health care personnel (39% of women and 29% of men). More support was especially needed by men who had lymphoma, had received chemotherapy or had a low education level. The results of this study show that the majority of the survivors are able to return to work. There is, however, a group of cancer survivors who leave work life early, have impaired work ability due to their illness, and suffer from lack of support from their work place and the occupational health services. Treatment-related, as well as sociodemographic factors play an important role in survivors' work-related problems, and presumably their possibilities to continue working.

Mammographic mass-screening and future breast cancer burden in Finland

A population-based early detection program for breast cancer has been in progress in Finland since 1987. According to regulations during the study period 1987-2001, free of charge mammography screening was offered every second year to women aged 50-59 years. Recently, the screening service was decided to be extended to age group 50-69. However, the scope of the program is still frequently discussed in public and information about potential impacts of mass-screening practice changes on future breast cancer burden is required. The aim of this doctoral thesis is to present methodologies for taking into account the mass-screening invitation information in breast cancer burden predictions, and to present alternative breast cancer incidence and mortality predictions up to 2012 based on scenarios of the future screening policy. The focus of this work is not on assessing the absolute efficacy but the effectiveness of mass-screening, and, by utilizing the data on invitations, on showing the estimated impacts of changes in an existing screening program on the short-term predictions. The breast cancer mortality predictions are calculated using a model that combines incidence, cause-specific and other cause survival on individual level. The screening invitation data are incorporated into modeling of breast cancer incidence and survival by dividing the program into separate components (first and subsequent rounds and years within them, breaks, and post screening period) and defining a variable that gives the component of the screening program. The incidence is modeled using a Poisson regression approach and the breast cancer survival by applying a parametric mixture cure model, where the patient population is allowed to be a combination of cured and uncured patients. The patients risk to die from other causes than breast cancer is allowed to differ from that of a corresponding general population group and to depend on age and follow-up time. As a result, the effects of separate components of the screening program on incidence, proportion of cured and the survival of the uncured are quantified. According to the predictions, the impacts of policy changes, like extending the program from age group 50-59 to 50-69, are clearly visible on incidence while the effects on mortality in age group 40-74 are minor. Extending the screening service would increase the incidence of localized breast cancers but decrease the rates of non-localized breast cancer. There were no major differences between mortality predictions yielded by alternative future scenarios of the screening policy: Any policy change would have at the most a 3.0% reduction on overall breast cancer mortality compared to continuing the current practice in the near future.

Molecular basis of colorectal cancer predisposition

Colorectal cancer (CRC) is one of the most frequent malignancies in Western countries. Inherited factors have been suggested to be involved in 35% of CRCs. The hereditary CRC syndromes explain only ~6% of all CRCs, indicating that a large proportion of the inherited susceptibility is still unexplained. Much of the remaining genetic predisposition for CRC is probably due to undiscovered low-penetrance variations. This study was conducted to identify germline and somatic changes that contribute to CRC predisposition and tumorigenesis. MLH1 and MSH2, that underlie Hereditary non-polyposis colorectal cancer (HNPCC) are considered to be tumor suppressor genes; the first hit is inherited in the germline and somatic inactivation of the wild type allele is required for tumor initiation. In a recent study, frequent loss of the mutant allele in HNPCC tumors was detected and a new model, arguing against the two-hit hypothesis, was proposed for somatic HNPCC tumorigenesis. We tested this hypothesis by conducting LOH analysis on 25 colorectal HNPCC tumors with a known germline mutation in the MLH1 or MSH2 genes. LOH was detected in 56% of the tumors. All the losses targeted the wild type allele supporting the classical two-hit model for HNPCC tumorigenesis. The variants 3020insC, R702W and G908R in NOD2 predispose to Crohn s disease. Contribution of NOD2 to CRC predisposition has been examined in several case-control series, with conflicting results. We have previously shown that 3020insC does not predispose to CRC in Finnish CRC patients. To expand our previous study the variants R702W and G908R were genotyped in a population-based series of 1042 Finnish CRC patients and 508 healthy controls. Association analyses did not show significant evidence for association of the variants with CRC. Single nucleotide polymorphism (SNP) rs6983267 at chromosome 8q24 was the first CRC susceptibility variant identified through genome-wide association studies. To characterize the role of rs6983267 in CRC predisposition in the Finnish population, we genotyped the SNP in the case-control material of 1042 cases and 1012 controls and showed that G allele of rs6983267 is associated with the increased risk of CRC (OR 1.22; P=0.0018). Examination of allelic imbalance in the tumors heterozygous for rs6983267 revealed that copy number increase affected 22% of the tumors and interestingly, it favored the G allele. By utilizing a computer algorithm, Enhancer Element Locator (EEL), an evolutionary conserved regulatory motif containing rs6983267 was identified. The SNP affected the binding site of TCF4, a transcription factor that mediates Wnt signaling in cells, and has proven to be crucial in colorectal neoplasia. The preferential binding of TCF4 to the risk allele G was showed in vitro and in vivo. The element drove lacZ marker gene expression in mouse embryos in a pattern that is consistent with genes regulated by the Wnt signaling pathway. These results suggest that rs6983267 at 8q24 exerts its effect in CRC predisposition by regulating gene expression. The most obvious target gene for the enhancer element is MYC, residing ~335 kb downstream, however further studies are required to establish the transcriptional target(s) of the predicted enhancer element.

Pro-apoptotic NOXA is implicated in atmospheric-pressure plasma-induced melanoma cell death

Atmospheric-pressure plasma (APP) has been successfully used to treat several types of cancers in vivo and in vitro, with the effect being primarily attributed to the generation of reactive oxygen species (ROS). However, the mechanisms by which APP induces apoptosis in cancer cells require further elucidation. In this study, the effects of APP on the expression of 500 genes in melanoma Mel007 cancer cells were examined. Pro-apoptotic phorbol-12-myristate-13-acetate-induced protein (PMAIP1), also known as NOXA, was highly expressed as a result of APP treatment in a dose-dependent manner. Blocking of ROS using scavenger NAC or silencing of NOXA gene by RNA interference inhibited the APP-induced NOXA genes upregulation and impaired caspases 3/7 mediated apoptosis, confirming the important role plasma-generated ROS species and pro-apoptotic NOXA play in APP-induced cancer cell death.

Molecular Alterations in Asbestos-Related Lung Cancer

Background: Asbestos is a well known cancer-causing mineral fibre, which has a synergistic effect on lung cancer risk in combination with tobacco smoking. Several in vitro and in vivo experiments have demonstrated that asbestos can evoke chromosomal damage and cause alterations as well as gene expression changes. Lung tumours, in general, have very complex karyotypes with several recurrently gained and lost chromosomal regions and this has made it difficult to identify specific molecular changes related primarily to asbestos exposure. The main aim of these studies has been to characterize asbestos-related lung cancer at a molecular level. Methods: Samples from asbestos-exposed and non-exposed lung cancer patients were studied using array comparative genomic hybridization (aCGH) and fluorescent in situ hybridization (FISH) to detect copy number alterations (CNA) as well as microsatellite analysis to detect allelic imbalance (AI). In addition, asbestos-exposed cell lines were studied using gene expression microarrays. Results: Eighteen chromosomal regions showing differential copy number in the lung tumours of asbestos-exposed patients compared to those of non-exposed patients were identified. The most significant differences were detected at 2p21-p16.3, 5q35.3, 9q33.3-q34.11, 9q34.13-q34.3, 11p15.5, 14q11.2 and 19p13.1-p13.3 (p<0.005). The alterations at 2p and 9q were validated and characterized in detail using AI and FISH analysis in a larger study population. Furthermore, in vitro studies were performed to examine the early gene expression changes induced by asbestos in three different lung cell lines. The results revealed specific asbestos-associated gene expression profiles and biological processes as well as chromosomal regions enriched with genes believed to contribute to the common asbestos-related responses in the cell lines. Interestingly, the most significant region enriched with asbestos-response genes was identified at 2p22, close to the previously identified region showing asbestos-related CNA in lung tumours. Additionally, in this thesis, the dysregulated biological processes (Gene Ontology terms) detected in the cell line experiment were compared to dysregulated processes identified in patient samples in a later study (Ruosaari et al., 2008a). Commonly affected processes such as those related to protein ubiquitination, ion transport and surprisingly sensory perception of smell were identified. Conclusions: The identification of specific CNA and dysregulated biological processes shed some light on the underlying genes acting as mediators in asbestos-related lung carcinogenesis. It is postulated that the combination of several asbestos-specific molecular alterations could be used to develop a diagnostic method for the identification of asbestos-related lung cancer.