Radiation-induced Release of Transforming Growth Factor α Activates the Epidermal Growth Factor Receptor and Mitogen-activated Protein Kinase Pathway in Carcinoma Cells, Leading to Increased Proliferation and Protection from Radiation-induced Cell Death

Exposure of A431 squamous and MDA-MB-231 mammary carcinoma cells to ionizing radiation has been associated with short transient increases in epidermal growth factor receptor (EGFR) tyrosine phosphorylation and activation of the mitogen-activated protein kinase (MAPK) and c-Jun NH2-terminal kinase (JNK) pathways. Irradiation (2 Gy) of A431 and MDA-MB-231 cells caused immediate primary activations (0–10 min) of the EGFR and the MAPK and JNK pathways, which were surprisingly followed by later prolonged secondary activations (90–240 min). Primary and secondary activation of the EGFR was abolished by molecular inhibition of EGFR function. The primary and secondary activation of the MAPK pathway was abolished by molecular inhibition of either EGFR or Ras function. In contrast, molecular inhibition of EGFR function abolished the secondary but not the primary activation of the JNK pathway. Inhibition of tumor necrosis factor α receptor function by use of neutralizing monoclonal antibodies blunted primary activation of the JNK pathway. Addition of a neutralizing monoclonal antibody versus transforming growth factor α (TGFα) had no effect on the primary activation of either the EGFR or the MAPK and JNK pathways after irradiation but abolished the secondary activation of EGFR, MAPK, and JNK. Irradiation of cells increased pro-TGFα cleavage 120–180 min after exposure. In agreement with radiation-induced release of a soluble factor, activation of the EGFR and the MAPK and JNK pathways could be induced in nonirradiated cells by the transfer of media from irradiated cells 120 min after irradiation. The ability of the transferred media to cause MAPK and JNK activation was blocked when media were incubated with a neutralizing antibody to TGFα. Thus radiation causes primary and secondary activation of the EGFR and the MAPK and JNK pathways in autocrine-regulated carcinoma cells. Secondary activation of the EGFR and the MAPK and JNK pathways is dependent on radiation-induced cleavage and autocrine action of TGFα. Neutralization of TGFα function by an anti-TGFα antibody or inhibition of MAPK function by MEK1/2 inhibitors (PD98059 and U0126) radiosensitized A431 and MDA-MB-231 cells after irradiation in apoptosis, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), and clonogenic assays. These data demonstrate that disruption of the TGFα–EGFR–MAPK signaling module represents a strategy to decrease carcinoma cell growth and survival after irradiation.

Telomerase activity in the regenerative basal layer of the epidermis inhuman skin and in immortal and carcinoma-derived skin keratinocytes.

Cellular senescence is defined by the limited proliferative capacity of normal cultured cells. Immortal cells overcome this regulation and proliferate indefinitively. One step in the immortalization process may be reactivation of telomerase activity, a ribonucleoprotein complex, which, by de novo synthesized telomeric TTAGGG repeats, can prevent shortening of the telomeres. Here we show that immortal human skin keratinocytes, irrespective of whether they were immortalized by simian virus 40, human papillomavirus 16, or spontaneously, as well as cell lines established from human skin squamous cell carcinomas exhibit telomerase activity. Unexpectedly, four of nine samples of intact human skin also were telomerase positive. By dissecting the skin we could show that the dermis and cultured dermal fibroblasts were telomerase negative. The epidermis and cultured skin keratinocytes, however, reproducibly exhibited enzyme activity. By separating different cell layers of the epidermis this telomerase activity could be assigned to the proliferative basal cells. Thus, in addition to hematopoietic cells, the epidermis, another example of a permanently regenerating human tissue, provides a further exception of the hypothesis that all normal human somatic tissues are telomerase deficient. Instead, these data suggest that in addition to contributing to the permanent proliferation capacity of immortal and tumor-derived keratinocytes, telomerase activity may also play a similar role in the lifetime regenerative capacity of normal epidermis in vivo.

Resistência de células de carcinoma epidermóide bucal à terapia fotodinâmica mediada pelo ácido 5-aminolevulínico

O carcinoma epidermóide bucal (CEC) é uma neoplasia maligna com alta morbidade e mortalidade e de difícil tratamento. O tratamento convencional para o CEC inclui cirurgia e radioterapia, seguida ou não de quimioterapia. Apesar de serem amplamente difundidos, esses tratamentos podem ser ineficazes para alguns CECs resistentes. A terapia fotodinâmica (PDT) oncológica tem sido utilizada para o tratamento adjuvante do CEC bucal, principalmente nos casos menos invasivos e que necessitam de redução do tumor para a ressecção cirúrgica. Contudo, semelhantemente aos tratamentos convencionais, a PDT pode também induzir o aparecimento de populações celulares resistentes, fato já descrito para carcinoma cutâneo, adenocarcinoma de cólon e adenocarcinoma mamário. A hipótese de que células de CEC bucal possam desenvolver resistência à PDT ainda não foi testada. Portanto, o objetivo deste trabalho foi verificar se células de CEC bucal (SCC9) desenvolvem resistência a ciclos repetidos de PDT mediada pelo ácido 5- aminolevulínico (5-ALA-PDT) e avaliar se nesse processo ocorre modificação da expressão de marcadores relacionados a sobrevivência celular (NF?B, Bcl-2, iNOS, mTOR e Akt). Foi utilizada linhagem de células de CEC bucal (SCC9), submetida às seguintes condições: 1) Controle - células cultivadas sem nenhum tratamento; 2) ALA - células incubadas com 5-ALA (1mM durante 4 horas); 3) LED - tratadas com iluminação LED (630nm, 5,86J/cm2, 22,5J, 150mW, 150s); 4) PDT - tratadas com 5- ALA-PDT, com os protocolos do grupo ALA e LED combinados, gerando dose letal de 90%. Inicialmente foi realizado somente um ciclo de PDT, sendo avaliada a viabilidade celular em todos os grupos após 24, 48, 72 e 120h da irradiação. Também foi realizado ensaio de detecção da fragmentação de DNA (TUNEL) e análise por imunofluorescência da expressão das proteínas NF?B, Bcl-2, iNOS, pmTOR e pAkt nas células viáveis. Como resultado desse primeiro tratamento com 5-ALA-PDT, observou-se que as células sobreviventes ao tratamento apresentaram intensa marcação para pmTOR e exibiram potencial de crescimento durante o período analisado. Após esses ensaios, as células que sobreviveram a essa primeira sessão foram coletadas, replaqueadas e novamente cultivadas, sendo então submetidas a novo ciclo de 5-ALA-PDT. Esse processo foi realizado 5 vezes, variando-se a intensidade de irradiação à medida que se observava aumento na viabilidade celular. As populações celulares que exibiram viabilidade 1,5 vezes maior do que a detectada no primeiro ciclo PDT foram consideradas resistentes ao tratamento. Os mesmos marcadores analisados no primeiro ciclo de PDT foram novamente avaliados nas populações resistentes. Foram obtidas quatro populações celulares resistentes, com viabilidade de até 4,6 vezes maior do que a do primeiro ciclo de PDT e irradiação com LED que variou de 5,86 a 9,38J/cm2. A população mais resistente apresentou ainda menor intensidade de protoporfirina IX, maior capacidade de migração e modificação na morfologia nuclear. As populações resistentes testadas exibiram aumento na expressão de pNF?B, iNOS, pmTOR e pAkt, mas não da proteína anti-apoptótica Bcl- 2. Ensaio in vivo foi também conduzido em ratos, nos quais CEC bucal foi quimicamente induzido e tratado ou não com 5-ALA-PDT. Houve intensa expressão imuno-histoquímica das proteínas pNF?B, Bcl-2, iNOS, pmTOR e pAkt em relação ao controle não tratado, nas células adjacentes à área de necrose provocada pela PDT. Concluiu-se que as células de CEC bucal tratadas com 5-ALA-PDT a uma dose de 90% de letalidade desenvolveram viabilidade crescente após ciclos repetidos do tratamento, bem como exibiram superexpressão de proteínas relacionadas à sobrevivência celular, tanto in vitro quanto in vivo. Esses fatos, aliados à maior capacidade de migração, sugerem a aquisição de fenótipo de resistência à 5-ALAPDT. Esse aspecto deve ser cuidadosamente considerado no momento da instituição dessa terapia para os CECs bucais.

Expressão dos receptores Toll-like em carcinoma espinocelular de orofaringe

Nos últimos anos, notou-se aumento da incidência de carcinoma espinocelular de orofaringe (CECOF) associado ao HPV. Sabe-se que CECOF associado ao HPV apresenta melhor prognóstico do que CECOF não infectado por HPV. Inúmeros estudos em carcinoma cervical demonstram alterações de TLRs, isto provavelmente devido às associações das oncoproteínas E6 e E7 com estes receptores. Em humanos, existem 10 TLRs identificados, os quais colaboram na resposta imune contra bactérias, fungos e vírus, bem como colaboram na promoção ou regressão do tumor. Esta influência do TLR na carcinogênese tem sido alvo de inúmeros estudos devido à ligação entre inflamação e o câncer. O presente trabalho teve como objetivo verificar diferenças na expressão e função de receptores Toll-like em carcinoma espinocelular de orofaringe (CECOF). Para tal, foram utilizados trinta e sete espécimes diagnosticados como CECOF e a expressão imuno-histoquímica das proteínas p16 e TLR4 analisadas. Duas linhagens de CECOF HPV16 + e duas CECOF HPV-. foram utilizadas para análise da expressão de TLR1-10, IL-6 e IL-8, por qPCR. A detecção dos principais TLRs (TLR1, TLR2, TLR6 e TLR4) foi feita por citometria de fluxo. Para ativação da via de sinalização de TLR2, e posterior análise da expressão de IL6 e IL8, as células foram estimuladas com peptidoglicano. Para verificar a expressão e função de TLR4, as células foram estimuladas com LPS e LPS UP para posterior análise de IL-6 e IL-8, por ELISA. Os resultados demonstraram diferenças na expressão gênica de TLR1 e TLR6 entre as linhagens HPV- e o grupo HPV+ e diferenças na expressão proteica de TLR9. TLR2 apresentou aumento da expressão proteica em todas as linhagens e demonstra desencadeamento da resposta imune, com secreção de IL6 e IL8 nas linhagens HPV- (SCC72 e SCC89) e em uma das linhagens HPV+ (SCC2). Interessantemente, TLR4 não apresentou diferenças significativas na expressão gênica e proteica. Entretanto, as linhagens HPV+ não demonstraram resposta pró-inflamatória mesmo quando estimuladas com LPS e LPS ultra puro, agonista específico de TLR4. Assim, este trabalho contribui para estabelecer o perfil da expressão dos receptores Toll-like em linhagens celulares de CECOF HPV- e HPV+, e aponta para alterações ocorridas na via de sinalização mediada por TLR4. Além disso, nossos resultados abrem portas para futuros estudos na avaliação de alterações causadas no sistema imune inato pelo HPV, em carcinomas espinocelulares de orofaringe.

Avaliação do potencial antiproliferativo do Dendrímero de Poliglicerol associado ao celecoxibe em linhagens celulares de carcinoma epidermoide de cabeça e pescoço

Diversos mecanismos celulares estão associados à patogênese do Carcinoma Epidermoide de Cabeça e Pescoço (CECP). Algumas dessas alterações envolvem proteínas pertencentes à via de sinalização do Akt, e o fator de transcrição NF-kB, o qual têm importante papel na fisiologia normal e no câncer. A proteína COX-2, descrita em processos inflamatórios, também participa da carcinogênese e está associada com a via de sinalização do Akt e com o NF-kB. Dendrímeros são uma forma única de nanotecnologia, surgindo como nanotransportadores com a capacidade de penetrar na célula tumoral liberando drogas quimioterápicas em seu interior. Os benefícios desta tecnologia são o aumento da eficicácia do princípio ativo utilizado e a redução dos seus efeitos secundários tóxicos. O Celecoxibe, antiinflamatório não esteroidal, inibidor seletivo da COX-2, tem se mostrado um importante agente anticarcinogênico, no entanto seu mecanismo de ação no CECP não é totalmente compreendido. Neste trabalho, um Dendrímero de Poliglicerol associado ao Celecoxibe (PGLD-celecoxibe) foi sintetizado e caracterizado por técnicas de espectroscopia ¹H-RMN, ¹³C-RMN, Maldi-Tof, TLC e DSC. Além disso, o conjugado foi testado in vitro em três linhagens celulares de CECP. O PGLD-Celecoxibe foi sintetizado com sucesso e promoveu a redução da dose capaz de inibir a proliferação celular, reduzindo o IC 50 do Celecoxibe de forma significativa em todas as linhagens celulares, se aproximando da dose sérica alcançada por este medicamento, resultado corroborado pelo Ensaio de Migração Celular. O mecanismo de morte celular observado foi a apoptose, associada a diminuição significativa da expressão de COX-2 ou por uma via alternativa independente. Alguns dos grupos tratados apresentaram alteração na expressão das proteínas pAkt e NF-kB.

Detecção dos herpesvirus humanos na mucosa oral de pacientes irradiados para tratamento de carcinoma epidermoide em região de cabeça e pescoço

A radioterapia para tratamento das neoplasias malignas em região de cabeça e pescoço é acompanhada de diversas complicações, decorrentes do comprometimento dos tecidos radiossensíveis localizados próximos ao tumor. Entre essas complicações a mucosite é a que merece maior destaque. A mucosite é uma reação tóxica inflamatória da mucosa oral causada pelo tratamento citorredutivo induzido pela radioterapia (RT) ou pela quimioterapia (QT). Ela manifesta-se com sinais de edema, eritema, úlcera e formação pseudomembrana, resultando em sintomas de ardência, que pode progredir para dor intensa e consequente prejuízo na alimentação e comunicação verbal. Infecções bacterianas, fúngicas ou virais podem acometer a mucosa bucal irradiada e exacerbar a manifestação da mucosite oral por meio da ativação de fatores de transcrição da resposta inflamatória. Existem poucos dados na literatura sobre a participação dos herpesvirus humanos na mucosite oral induzida pela radioterapia. A proposta desse trabalho foi avaliar a excreção oral dos herpesvirus humanos (HSV-1, HSV-2, EBV, CMV, VZV, HHV6, HHV7 e HHV8) e sua possível associação com o desenvolvimento e agravamento da mucosite oral, em pacientes diagnosticados com carcinoma epidermoide (CEC) de boca e orofaringe, submetidos à radioterapia associado à quimioterapia. Nesse estudo foram analisadas 158 amostras de lavado bucal, de 20 pacientes, submetidos à radioterapia para CEC em região de cabeça e pescoço, coletadas semanalmente, durante todo o tratamento. Foi realizada a extração do DNA dessas amostras e em seguida sua amplificação através da PCR utilizando dois conjuntos de primers: HSVP1/P2 para os subtipos HSV-1, HSV-2, EBV, CMV e HHV-8 e o VZVP1/P2 para os subtipos VZV, HHV-6 e HHV-7. As amostras positivas foram submetidas à digestão enzimática com enzimas de restrição BamHI e BstUI para determinação específica de cada um dos oito herpesvirus. Foi também avaliada clinicamente, a mucosite oral, em cada uma das coletas, seguindo os critérios da OMS e NCIC. As análises da amostra mostraram a excreção do EBV, HHV-6 e HHV-7, em todas as semanas de tratamento radioterápico, enquanto que a excreção do HSV1 não pode ser observada no momento da triagem. Considerando-se todos os períodos em conjunto (Triagem, semanas de radioterapia e Controle), a maior frequência foi de pacientes que excretaram EBV (55,0%), seguida daqueles que excretaram HHV-7 (20,5%). A frequência de excreção de EBV foi significativamente maior do que a dos demais vírus (Teste ?2, p<0.001 para todos os cruzamentos). A frequência de excreção de HHV-7 foi significativamente maior do que a de HSV-1 (5,9%) e HHV-6 (5,5%) (Teste ?2, p=0.001 para ambos os cruzamentos). Não houve diferenças estatísticas significantes entre as frequências de HSV-1 e HHV-6. Como conclusão, verificou-se uma correlação positiva entre a excreção oral do EBV e a presença de mucosite induzida pela associação de radioterapia e quimioterapia com graus >=2, sobretudo se considerarmos as três últimas semanas de radioterapia, período este em que a severidade da mucosite foi estatisticamente maior. Esses achados nos possibilitam inferir que o ambiente inflamatório local de mucosites com grau >=2 seja mais favorável para excreção oral do EBV.

Use of oesophagogastroscopy to assess the response of oesophageal carcinoma to neoadjuvant therapy

Background: Approximately 25 per cent of patients with oesophageal cancer who undergo neoadjuvant chemoradiotherapy have no evidence of tumour in the resected specimen (complete pathological response). Those who do not respond have a poor 5-year survival compared with complete responders, regardless of whether or not they undergo surgery. Selecting for surgery only those who have a response to neoadjuvant therapy has the potential to improve overall survival as well as to rationalize the management of non-responders. This study assessed the accuracy of oesophagogastroscopy in this setting. Methods: A prospective database of 804 patients undergoing oesophageal resection for carcinoma was reviewed. Endoscopic assessment of the response to neoadjuvant therapy in 100 consecutive patients was compared with the pathological assessment of response. The survival for each level of response was compared. Results: At endoscopy 30 patients were considered to have had a complete response. This was confirmed pathologically in 15 patients. Survival was improved in those with a pathologically confirmed complete response (3-year survival rate 62.4 (s.e. 12.9) per cent) compared with non-responders (16.3 (s.e. 6.6) per cent). Those with microscopic residual disease also had an improved 3-year survival rate (46.3 (s.e. 12.2) per cent); however, oesophagogastroscopy failed to identify this subset. Conclusion: Oesophagogastroscopy may be useful in the assessment of tumour response to neoadjuvant therapy. However, owing to its poor accuracy patients should not be excluded from further therapeutic intervention on the basis of this assessment alone.

E2F6: a member of the E2F family that does not modulate squamous differentiation

The inhibition of E2F has been demonstrated to be important in the initiation of squamous differentiation by two independent manners: promotion of growth arrest and the relief of the differentiation-suppressive properties of E2Fs. E2F6 is reported to behave as a transcriptional repressor of the E2F family. In this study, we examined the ability of E2F6 to act as the molecular switch required for E2F inhibition in order for keratinocytes to enter a terminal differentiation programme. Results demonstrated that whilst E2F6 was able to suppress E2F activity in proliferating keratinocytes, it did not modulate squamous differentiation in a differentiated keratinocyte. Furthermore, inhibition of E2F, by overexpressing E2F6, was not sufficient to sensitise either proliferating keratinocytes or the squamous cell carcinoma cell line, KJD-1/SV40, to differentiation-inducing agents. Significantly, although E2F6 could suppress E2F activity in proliferating cells, it could not inhibit proliferation of KJD-1/SV40 cells. These results demonstrate that E2F6 does not contain the domains required for modulation of squamous differentiation and imply isoform-specific functions for individual E2F family members. (C) 2004 Elsevier Inc. All rights reserved.

The effect of skin examination surveys on the incidence of basal cell carcinoma in a Queensland community sample: A 10-year longitudinal study

Skin cancers pose a significant public health problem in high-risk populations. We have prospectively monitored basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) incidence in a Queensland community over a 10-y period by recording newly treated lesions, supplemented by skin examination surveys. Age-standardized incidence rates of people with new histologically confirmed BCC were 2787 per 100,000 person-years at risk (pyar) among men and 1567 per 100,000 pyar among women, and corresponding tumor rates were 5821 per 100,000 pyar and 2733 per 100,000 pyar, respectively. Incidence rates for men with new SCC were 944 per 100,000 pyar and for women 675 per 100,000 pyar; tumor rates were 1754 per 100,000 pyar and 846 per 100,000 pyar, respectively. Incidence rates of BCC tumors but not SCC tumors varied noticeably according to method of surveillance, with BCC incidence rates based on skin examination surveys around three times higher than background treatment rates. This was mostly due to an increase in diagnosis of new BCC on sites other than the head and neck, arms, and hands associated with skin examination surveys and little to do with advancing the time of diagnosis of BCC on these sites as seen by a return to background rates following the examination surveys. We conclude that BCC that might otherwise go unreported are detected during skin examination surveys and thus that such skin cancer screening can influence the apparent burden of skin cancer.

Role of dietary factors in the development of basal cell cancer and squamous cell cancer of the skin

The role of dietary factors in the development of skin cancer has been investigated for many years; however, the results of epidemiologic studies have not been systematically reviewed. This article reviews human studies of basal cell cancer (BCC) and squamous cell cancer (SCC) and includes all studies identified in the published scientific literature investigating dietary exposure to fats, retinol, carotenoids, vitamin E, vitamin Q and selenium. A total of 26 studies were critically reviewed according to study design and quality of the epidemiologic evidence. Overall, the evidence suggests a positive relationship between fat intake and BCC and SCC, an inconsistent association for retinol, and little relation between beta-carotene and BCC or SCC development. There is insufficient evidence on which to make a judgment about an association of other carotenoids with skin cancer. The evidence for associations between vitamin E, vitamin C, and selenium and both BCC and SCC is weak. Many of the existing studies contain limitations, however, and further well-designed and implemented studies are required to clarify the role of diet in skin cancer. Additionally, the role of other dietary factors, such as flavonoids and other polyphenols, which have been implicated in skin cancer development in animal models, needs to be investigated.

Specific morphological features predictive for the basal phenotype in grade 3 invasive ductal carcinoma of breast

Aims: Cytokeratin (CK) 14, a myoepithelial marker, is also expressed in a proportion of breast carcinomas. There is evidence that these tumours show a differing metastatic pattern and clinical outcome from other invasive ductal carcinomas (IDCs) and may need different management. Currently, they are not identified in routine practice and no morphological guidelines exist to aid their identification. The aim of this study was to analyse the histological features of CK14+ IDC. Methods and results: A detailed histological review of 453 grade 3 IDCs revealed 88 (19.4%) that expressed CK14. Assessment was made independently by two pathologists using a standardized 'tick-box' proforma covering grade, architectural and cytological features. The results were analysed using logistic regression to identify features that predicted for basal phenotype. Concordance between the two pathologists was fair to good for most parameters (kappa 0.4-0.6). On multiple logistic regression, the basal phenotype was highly significantly associated with the presence of a central scar (P = 0.005), tumour necrosis (P < 0.0001), presence of spindle cells (P = 0.006) or squamous metaplasia (P < 0.0001), high total mitotic count (> 40 per 10 high-power field) (P = 0.0002) and high nuclear-cytoplasmic ratio (P = 0.0002). Conclusions: Specific morphological features are strongly associated with basal-like breast carcinoma. These could be used in routine diagnostic practice to identify this important subset of tumours.

Topical interferon alfa-2b for the treatment of recalcitrant ocular surface squamous neoplasia

center dot PURPOSE: To evaluate topical interferon alfa-2b (IFN-alpha 2b) for the treatment of recalcitrant ocular surface squamous neoplasia (OSSN). center dot DESIGN: Prospective, noncomparative, interventional consecutive case series. center dot METHODS: Ten patients with recalcitrant OSSN were treated with topical IFN-alpha 2b (1 million IU/ml) four times a day until clinical resolution of the lesion or until the lesion appeared nonresponsive-that is, treatment failure. Progress was assessed by clinical examination and photographic records, with a minimum follow,up of six months. center dot RESULTS: Eight of 10 patients achieved clinical resolution from topical IFN-alpha 2b treatment. One patient developed invasive squamous cell carcinoma and underwent exenteration. The other patient required further mitomycin C therapy to achieve clinical resolution. The mean duration to clinical resolution for the eight patients treated with IFN-alpha 2b was 21.9 weeks (range six to 59 weeks). There have been no recurrences for any of the nine patients during follow-up (mean 55.0 weeks; range 26 to 84 weeks). center dot CONCLUSIONS: Topical IFN-alpha 2b is an important treatment modality for recalcitrant OSSN; it avoids the risks of further limbal stem cell destruction from other agents and surgical excision. If invasive disease is diagnosed at any stage, topical therapy is contraindicated, necessitating surgical excision. (Am J Ophthalmol 2006; 142:568-571. (c) 2006 by Elsevier Inc. All rights reserved.)

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 shin 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 shin 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.

Análise comparativa da imunoexpressão do IMP-3 e Ki-67 em queilites actínicas e carcinoma epidermóide de lábio inferior

Epithelial changes observed in actinic cheilitis (AC) and squamous cell carcinoma of the lower lip (LLSCC) are mainly caused by chronic exposure to ultraviolet rays (UV) and are studied using different immunohistochemical markers trying to evaluate the process of carcinogenesis. The objective of this study was to comparatively evaluate the expression of Ki-67 proteins and IMP-3 in AC and LLSCC to contribute with additional information on carcinogenesis in lower lip. A total of 33 cases of AC and 33 cases of LLSCC were studied, analyzed the clinical and pathological features and immunostaining of Ki-67 and IMP-3. Immunohistochemical analysis of Ki-67 was made through the determination of the proliferation index (PI) and subsequent classification of the cases according to the scores: 0 (0% positive cells) +1 (≤30%) + 2 (> 30% and ≤60%) and +3 (> 60%). For statistical tests cases were classified as unmarked (score 0), low expression (score +1) and high expression (scores +2 and +3). For the expression of IMP-3, the percentage of immunostained epithelial cells was established, and assigned scores: 0 (corresponding to 0%), +1 (up to 30% of positive cells); +2 (From 30% to 60% of immunostained cells) and +3 (over 60% of positive cells). Statistical tests chi-square test, Mann-Whitney and Wilcoxon were used. The significance level was 5%. Most AC chaos was male (78.8%) with mean age of 50 years and cases of LLSCC also were male (69.89%) with an average of 62 years. The Ki-67 was expressed in all cases of AC and in cases of LLSCC, predominantly in the two injuries the score 2, corresponding to 81.8% of cases in ACs and 54.5% in the CELI. The expression of IMP-3 in ACs occurred in 72.7% of cases, predominantly in 36.3% of LLSCC cases score 1. Already in the IMP-3 was expressed in 60.6% of cases, especially in 27.3% of the score of the cases 3. These results allow us to conclude that the expression of IMP3 and proliferative activity are early events in carcinogenesis independently lower lip state of change.