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Resumo: A drenagem linfática profunda desempenha um papel importante no pulmão, uma vez que remove materiais estranhos depositados sobre a superfície das vias respiratórias, tais como microrganismos patogénicos. Esta drenagem está igualmente associada às vias de disseminação tumoral. Liposomas com uma membrana especificamente desenhada foram usados para simular partículas estranhas a ser removidas pelos linfáticos pulmonares. Pretendem obter-se imagens dos linfáticos profundos em babuínos usando liposomas que encapsulam 99mTc-HMPAO sob a forma de aerossol. Observaram-se gânglios linfáticos axilares 30 min pós-inalação, que se tornaram mais evidentes 1 hora após, quando os gânglios abdominais e aórticos também se tornaram visíveis. Imagens tardias não acrescentaram informação relevante. Foram desenhadas ROI's (regiões de interesse), bem como as correspondentes curvas de actividade-tempo para obter informação acerca da biocinética. Em conclusão, pode dizer-se que a técnica proposta torna possível a visualização da rede linfática profunda do pulmão e os gânglios linfáticos. Esta metodologia poderá vir a ser importante na libertação pulmonar controlada de fármacos citotóxicos. Abstract: Deep lymphatic drainage plays an important role in the lung, as it removes foreign materials laying on the airways surface, such as pathogenic microorganisms. This drainage is also associated with lung tumour dissemination route. Liposomes with a specially tailored membrane were used as foreign particles to be removed by the lung lymphatics. We aim to obtain images of deep lung lymphatics in baboons using liposomes encapsulating 99mTc-HMPAO, as aerosols. Axillary lymph nodes were visualized 30 min post-inhalation, becoming more evident 1 hour after, when abdominal aortic and inguinal lymph nodes were also observed. Late images added no additional information. ROI's and their time-activity curves were drawn to obtain biokinetic information. In conclusion, we can say that the proposed technique enables visualization of the deep lymphatic lung network and lymph nodes. This methodology may be an important tool for targeted lung delivery of cytotoxic drugs. Palavras-chave: Liposomas, Drenagem linfática, Cintigrafia, Libertação pulmonar controlada, Estudos in vivo, Keywords: Liposomes, Lymphatic drainage, Scintigraphy, Pulmonary delivery, In vivo studies

Small cell lung cancer (SCLC) is an aggressive disease, representing 15% of all cases of lung cancer, has high metastatic potential and low prognosis that urgently demands the development of novel therapeutic approaches. One of the proposed approaches has been the down-regulation of BCL2, with poorly clarified and controversial therapeutic value regarding SCLC. The use of anti-BCL2 small interfering RNA (siRNA) in SCLC has never been reported. The aim of the present study was to select and test the in vitro efficacy of anti-BCL2 siRNA sequences against the protein and mRNA levels of SCLC cells, and their effects on cytotoxicity and chemosensitization. Two anti-BCL2 siRNAs and the anti-BCL2 G3139 oligodeoxynucleotide (ODN) were evaluated in SCLC cells by the simultaneous determination of Bcl-2 and viability using a flow cytometry method recently developed by us in addition to Western blot, real-time reverse-transcription PCR, and cell growth after single and combined treatment with cisplatin. In contrast to previous reports about the use of ODN, a heterogeneous and up to 80% sequence-specific Bcl-2 protein knockdown was observed in the SW2, H2171 and H69 SCLC cell lines, although without significant sequence-specific reduction of cell viability, cell growth, or sensitization to cisplatin. Our results question previous data generated with antisense ODN and supporting the present concept of the therapeutic interest in BCL2 silencing per se in SCLC, and support the growing notion of the necessity of a multitargeting molecular approach for the treatment of cancer.

The aim of the present study was to characterize the interactions of antagonist G (H-Arg-D-Trp-NmePhe-D-Trp-Leu-Met-NH 2)-targeted sterically stabilized liposomes with the human variant small cell lung cancer (SCLC) H82 cell line and to evaluate the antiproliferative activity of encapsulated doxorubicin against this cell line. Variant SCLC tumors are known to be more resistant to chemotherapy than classic SCLC tumors. The cellular association of antagonist G-targeted (radiolabeled) liposomes was 20-30-fold higher than that of non-targeted liposomes. Our data suggest that a maximum of 12,000 antagonist G-targeted liposomes were internalized/cell during 1-h incubation at 37ºC. Confocal microscopy experiments using pyranine-containing liposomes further confirmed that receptor-mediated endocytosis occurred, specifically in the case of targeted liposomes. In any of the previously mentioned experiments, the binding and endocytosis of non-targeted liposomes have revealed to be negligible. The improved cellular association of antagonist G-targeted liposomes, relative to non-targeted liposomes, resulted in an enhanced nuclear delivery (evaluated by fluorimetry) and cytotoxicity of encapsulated doxorubicin for incubation periods as short as 2 h. For an incubation of 2 h, we report IC50 values for targeted and non-targeted liposomes containing doxorubicin of 5.7 ± 3.7 and higher than 200 µM doxorubicin, respectively. Based on the present data, we may infer that receptors for antagonist G were present in H82 tumor cells and could mediate the internalization of antagonist G-targeted liposomes and the intracellular delivery of their content. Antagonist G covalently coupled to liposomal drugs may be promising for the treatment of this aggressive and highly heterogeneous disease.