Phosphorylation at Ser-181 of oncogenic KRAS is required for tumor growth

KRAS phosphorylation has been reported recently to modulate the activity of mutant KRAS protein in vitro. In this study, we defined S181 as a specific phosphorylation site required to license the oncogenic function of mutant KRAS in vivo. The phosphomutant S181A failed to induce tumors in mice, whereas the phosphomimetic mutant S181D exhibited an enhanced tumor formation capacity, compared with the wild-type KRAS protein. Reduced growth of tumors composed of cells expressing the nonphosphorylatable KRAS S181A mutant was correlated with increased apoptosis. Conversely, increased growth of tumors composed of cells expressing the phosphomimetic KRAS S181D mutant was correlated with increased activation of AKT and ERK, two major downstream effectors of KRAS. Pharmacologic treatment with PKC inhibitors impaired tumor growth associated with reduced levels of phosphorylated KRAS and reduced effector activation. In a panel of human tumor cell lines expressing various KRAS isoforms, we showed that KRAS phosphorylation was essential for survival and tumorigenic activity. Furthermore, we identified phosphorylated KRAS in a panel of primary human pancreatic tumors. Taken together, our findings establish that KRAS requires S181 phosphorylation to manifest its oncogenic properties, implying that its inhibition represents a relevant target to attack KRAS-driven tumors.

Orthotopic PC-3 Tumor Xenografts in Studies on Prostate Cancer Growth and Metastasis

Prostate cancer is generally a slowly developing disease. However, some cancers develop into an aggressive, metastasic and consequently life-threatening state. The mechanisms of prostate cancer spread are still mainly unidentified but hormones and growth factors are known to been involved. The forming of new blood vessels i.e. angiogenesis is crucial for tumor growth. Blood vessels and lymphatic vessels are also prominent routes for metastasis. Both angiogenic and lymphangiogenic factors are overexpressed in prostate cancer. We established an in vivo model to study the factors effecting human prostate cancer growth and metastasis. Tumors were produced by the orthotopic inoculation of PC-3 prostate cancer cells into the prostates of immunodeficient mice. Like human prostate tumors, these tumors metastasized to prostate-draining lymph nodes. Treatment of the mice with the bisphosphonate alendronate known to decrease prostate cancer cell invasion in vitro inhibited metastasis and decreased tumor growth. Decreased tumor growth was associated with decreased angiogenesis and increased apoptosis of tumor cells. To elucidate the role of angiogenesis in prostate cancer progression, we studied the growth of orthotopic PC-3 tumors overexpressing fibroblast growth factor b (FGF8b) known to be expressed in human prostate cancer. FGF8b increased tumor growth and angiogenesis, which were both associated with a characteristic gene expression pattern. To study the role of lymphangiogenesis, we produced orthotopic PC-3 tumors overexpressing vascular endothelial growth factor C (VEGF-C). Blocking of VEGF-C receptor (VEGFR3) completely inhibited lymph node metastasis whereas overexpression of VEGF-C increased tumor growth and angiogenesis. VEGF-C also increased lung metastases but, surprisingly, decreased spread to lymph nodes. This suggests that the expanded vascular network was primarily used as a route for tumor spreading. Finally, the functionality of the capillary network in subcutaneous FGF8b-overexpressing PC-3 tumors was compared to that of tumors overexpressing VEGF. Both tumors showed angiogenic morphology and grew faster than control tumors. However, FGF8b tumors were hypoxic and their perfusion and oxygenation was poor compared with VEGF tumors. This suggests that the growth advantage of FGF8b tumors is more likely due to stimulated proliferation than effective angiogenesis. In conclusion, these results show that orthotopic prostate tumors provide a useful model to explore the mechanisms of prostate cancer growth and metastasis.

Chemical modifications of a natural xanthone and antimicrobial activity against multidrug resistant Staphylococcus aureus and cytotoxicity against human tumor cell lines

A series of 15 ω-aminoalkoxylxanthones containing methyl, ethyl, propyl, tert-butylamino and piperidinyl moieties were synthesized from a natural xanthone isolated from a lichen species. These compounds were tested for their in vitro antibacterial properties against Gram-positive and Gram-negative bacteria and cytotoxicity against a number of human tumor cell lines was too evaluated. The newly synthesized derivatives revealed selective activity against Staphylococcus aureus (Gram-positive), and the most promising results are for a multidrug resistant strain, for which six of these compounds showed good activity (MICs 4 µg/mL). Many derivatives inhibited tumor cells growth and most compounds were active on multiple lines.

Tumor do saco vitelino primário em retroperitônio

A case of primary extragonadal yolk sac tumor in the retroperitoneum of a young adult male is reported. The symptoms were melena and weakness for two months. Radiologic studies suggested a retroperitoneal tumor infiltrating the duodenum, artery aorta and vein cava, was found. Partial resection was performed, remaining tumor around the vessels. Microscopic examination disclosed a yolk sac tumor infiltrating the duodenum. The patient was managed unsuccessfully with radiotherapy, but good results were actived with chemotherapy. Few cases like that were reported in the literature.

Cisto multilocular renal

O cisto multilocular renal é uma tumoração rara, de etiopatogenia discutida, que apresenta um aspecto macroscópico característico (parecendo favos de mel) mas histologia variável, o que ocasionou uma vasta sinonímia para esta afecção. Com os modernos métodos de diagnóstico por imagem, estes tumores podem ser suspeitados no pré-operatório, mas antes eram rotulados como provável nefroblastoma (Tumor de Wilms). Os autores descrevem as características de cinco casos observados nos Serviços de Cirurgia Pediátrica dos Hospitais Getúlio Vargas e da Lagoa, do Rio de Janeiro, e no Hospital Universitário de João Pessoa (Paraíba). Em todos, o sintoma predominante era uma massa abdominal, mas em um havia também hipertensão arterial. Todos os pacientes foram submetidos a nefrectomia e tiveram boa evolução pós-operatória. Apesar de pouco freqüente, o cisto multilocular renal deve ser lembrado no diagnóstico de qualquer massa renal em crianças, especialmente naquelas com menos de dois anos de idade, devido ao prognóstico favorável em comparação com o do tumor de Wilms. No adulto, o diagnóstico diferencial é feito principalmente com o adenocarcinoma cístico.

Metástase cervical de carcinoma epidermóide com tumor primário desconhecido

Revisamos nossa experiência com carcinoma epidermóide metastático (CEM) para o pescoço com tumor primário desconhecido com a intenção de evidenciar quando o tratamento radioterápico exclusivo ou o tratamento cirúrgico seguido de radioterapia teriam impacto positivo sobre a sobrevida. Este é um estudo retrospectivo de 54 pacientes com CEM tratados na Seção de Cirurgia de Cabeça e Pescoço do Hospital do Câncer/INCa entre 1986 e 1992. Quarenta e oito pacientes (89%) eram do sexo masculino, a idade média foi de 54 anos. Quarenta pacientes tinham metástase para linfonodos cervicais da cadeia jugular interna alta (nível 2). Utilizamos a classificação TNM da UICC de 1992 para estagiar os pacientes, onde oito pacientes foram classificados como N1, vinte como N2, 22 como N3, sendo que quatro pacientes permaneceram não classificados. Todos foram submetidos a endoscopia do trato aerodigestivo superior e raio X de tórax. Trinta e cinco pacientes foram submetidos a biópsia de aspiração com agulha fina. Trinta e oito pacientes tiveram tratamento com intenção curativa e 1.6 tiveram tratamento paliativo com radioterapia. Dos pacientes tratados com intenção curativa, dez foram submetidos a esvaziamento cervical e 28 tiveram tratamento exclusivo com radioterapia. Os 16 pacientes tratados com intenção paliativa foram excluídos dos cálculos de sobrevida e análise das recidivas. As recidivas cervicais foram analisadas usando o método do qui-quadrado, e as curvas de sobrevida foram comparadas usando-se o teste de Wilcoxon. A biópsia aspirativa com agulha fina alcançou o diagnóstico em 85% dos casos. Oito pacientes (15%) apresentaram metástase à distância. O tumor primário foi identificado subseqüentemente em 9% dos pacientes. Dezoito pacientes (64%) tratados com radioterapia exclusiva tiveram recidivas no pescoço, e três pacientes (33%) tratados com cirurgia + radioterapia tiveram recidivas no pescoço. (p=0,05) Os pacientes classificados como N2/N3 tratados com cirurgia + radioterapia tiveram melhores resultados do que os tratados com radioterapia exclusiva (respectivamente p=0,05 e p=0,09). Os pacientes Nl tiveram melhor sobrevida livre de doença do que os pacientes N2/N3 (respectivamente p=0,007 e p=0,OO7). A sobrevida livre de doença em cinco anos foi de 69% para os pacientes Nl, 11 % para os pacientes N2 e 15% para os pacientes N3. A sobrevida livre de doença para todos os estágios foi de 28%. A biópsia aspirativa com agulha fina é um bom meio para diagnóstico e deve ser usada rotineiramente.

Metástase cervical de tumor primário oculto: estudo de 107 casos

Foram avaliados retrospectivamente 107 pacientes com metástases cervicais de tumor primário oculto, atendidos entre 1977 e 1995 no Hospital Heliópolis. Considerou-se a influência de fatores epidemiológicos e características clínicas na recorrência da doença e sobrevida. O carcinoma epidermóide foi o tipo histológico mais freqüente, acometendo predominantemente as cadeias júgulo-carotídeas alta e média (níveis II e III). Noventa e três por cento dos pacientes apresentavam doença avançada (estadiamento N2 ou N3). A sobrevida livre de doença (SLD) aos 5 anos foi de 24%, sendo 40% para os pacientes com 55 anos ou menos e 8% para aqueles com mais de 55 anos (p = 0,01). Todos os pacientes com doença na cadeia júgulo-carotídea baixa (nível IV) apresentaram recidiva nos primeiros 12 meses após o tratamento. Os tumores indiferenciados apresentaram recidiva mais precocemente. Na análise multivariada os fatores idade, tipo de tratamento e estadiamento foram significativos (p<0,05).

Linfangioma cístico do mesentério: uma rara apresentação de abdômen agudo

Mesenteric cyst is a rare intra abdominal pathology. The incidence ranges from 1/100,000 to 1/250,000 hospital admissions. The authors present a case of a female patient, 20 years old, with abdominal pain for four months which three days had an acute onset of abdominal pain, and ultrasound revealed a cyst of mesentery within a dense fluid. The patient had been submitted to a laparotomy, and resection of the cyst. We emphasized the clinical symptoms, diagnostic evaluation and the therapeutic of this condition.

Linfangioma cístico do pâncreas

Lymphangiomas are benign neoplasias of lymphatic tissue, extremely rare in the pancreas. Three lymphangioma types exist: capillary, cavernous and cystic. The authors report a case of cystic lymphangioma of the pancreas, with incidental diagnosis to the abdominal ultrasonography on investigation of urinary symptoms in male patient. To the laparotomy upper cystic mass was identified in the pancreas, that was totally resected. The histological examination demonstrated a cystic lymphangioma of the pancreas. The cystic lymphangioma of the pancreas was discovered accidentally, being assintomatic in most of the cases. Treatment of choice is complete resection, otherwise recidive is higher than 50%.

Tumor estromal gastrointestinal de intestino delgado

Stromal tumors of the gastrointestinal tract (gists) represent relatively rare lesions that arise from connective tissue elements located along the entire length of the gut. They were initially identified by immunohistochemical investigation, proving their origin from nondifferentiated mesenchymal cells. Only a minority of this lesions, mainly those confined to the esophagus and rectum, have been shown to correspond to mature, well-differentiated types of neoplasms such as leiomyoma or leiomyosarcoma. The majority of gists corresponds to a heterogeneous group of lesions that have as their common denominator an immature proliferation of epithelioid or spindle cells arising from its muscle layers, or between them, showing partial or incomplete myoide, neural, ganglionic, or mixed features of differentiation. This case report intends to show a gist of small bowel in a male, 46 years old, with a two-year of evolution.

Tumor carcinóide do reto

The rectum is the second most common location of the carcinoid tumors of the gastrointestinal tract. It represents approximately one or two per cent of the rectal neoplasms. Metastases are less frequent and it presents a better prognosis than carcinoid tumors found in the digestive tract. Treatment is surgical and the technique to be used depends fundamentally on the size of the tumor and the degree of in the intestinal wall penetration. Lesions which are greater than one centimeter have been treated with local excision, while the ones greater than two centimeters have been submitted to a radical resection. This article presents a case of rectal carcinoid diagnosed and treated initially as adenocarcinoma by abdominal rectossigmoidectomy. There were no signs of recurrence after a period of five years and six months of post-surgical follow-up. Nowadays the validity of radical resection in the treatment of rectal carcinoids has been much questioned due to the fact that it has not shown a significant raise in survival rate when compared with patients who were submitted to a local resection.

Reatividade linfonodal com metástase cervical de tumor primário oculto: estudo de 24 pacientes

OBJETIVO: Avaliar a reatividade linfonodal em pacientes com metástase cervical de tumor primário oculto. MÉTODO: Foram avaliados retrospectivamente 24 pacientes submetidos a esvaziamento cervical entre 1983 e 1995 devido à metástase de tumor primário oculto. Os cortes histológicos dos 601 linfonodos resultantes foram corados pela hematoxilina-eosina e avaliados à microscopia óptica. A reatividade linfonodal considerou a presença de hiperplasia paracortical, hiperplasia de centro germinativo e hiperplasia sinusal. Foram avaliadas a relação da reatividade linfonodal, ruptura capsular, necrose e desmoplasia com a recidiva da doença. A análise estatística foi feita com Teste de Fisher com erro inferior a 5%. RESULTADOS: Setenta e sete por cento (77%) dos linfonodos se mostraram reativos. Cinqüenta e cinco por cento (55%) dos pacientes com hiperplasia paracortical ou mista e dezesseis por cento (16%) dos pacientes com hiperplasia de centro germinativo ou linfonodos não reativos estavam assintomáticos por ocasião do último retorno ambulatorial (p=0,11). A presença de necrose tumoral mostrou associação significativa com a presença de desmoplasia (p=0,02). CONCLUSÕES: A reatividade linfonodal é freqüente na maioria das metástases cervicais em tumor primário oculto e a necrose tumoral está diretamente ligada à presença de desmoplasia.

Tumor do apêndice vermiforme

Appendiceal tumors are rare and usually presented as acute appendicitis. They are incidentally discovered at an emergency surgery, in which case the decision-making is very difficult. The purpose of this report is discuss to the most appropriate management for appendiceal tumors. A retrospective analysis of one case treated at HU-UEL was undertaken and the literature was reviewed. The conclusion is that frozen section should be done whenever the appendiceal findings are atypical. For appendiceal carcinoids greater than 2 cm and adenocarcinomas, a right hemicolectomy is recommended. Appendectomy is apropriate for patients whose carcinoid tumors are 1 cm in diameter or less and for carcinoid tumors between 1 cm and 2 cm without extensive lymphatic permeation and mesenteric invasion. Every case should be searched for synchronous tumors.

Hamartoma cístico retrorretal

A 32-year-old woman was referred to our institution for a pelvic mass. She was asymptomatic and was found to have a mass on rectal examination. Magnetic resonance showed a large solid-cystic mass and the patient underwent complete surgical excision with pathologic findings suggesting retrorectal cyst-hamartoma. Tailgut cysts (or retrorectal cystic hamartomas) are rare congenital lesions settled in the retrorectal (presacral) space. They are made up of cysts lined by multiple types of epithelium, often predominantly mucin-secreting. The lesion requires complete surgical excision to prevent complications of recurrence, infection or carcinomatous degeneration.

Tumor estromal do trato gastrintestinal primário da papila duodenal

The majority gastrointestinal wall tumors previously considered leiomyomas or leiomyosarcomas were reclassified into Gastrointestinal Stromal Tumours because of typical imunohistochemic, genetic and biologic behaviors findings. We present a case report of Gastrointestinal Stromal Tumor primary of the duodenal papilla causing digestive haemorrage that was submitted to surgical treatment.