The incidence of differentiated thyroid cancer has been increasing. Nevertheless, its molecular mechanisms are not well understood. In recent years, extracellular nucleotides and nucleosides have emerged as important modulators of tumor microenvironment. Extracellular ATP is mainly hydrolyzed by NTPDase1/CD39 and NTPDase2/CD39L1, generating AMP, which is hydrolyzed by ecto-5'-nucleotidase (CD73) to adenosine, a possible promoter of tumor growth and metastasis. There are no studies evaluating the expression and functionality of these ectonucleotidases on normal or tumor-derived thyroid cells. Thus, we investigated the ability of thyroid cancer cells to hydrolyze extracellular ATP generating adenosine, and the expression of ecto-enzymes, as compared to normal cells. We found that normal thyroid derived cells presented a higher ability to hydrolyze ATP and higher mRNA levels for ENTDP1-2, when compared to papillary thyroid carcinoma (PTC) derived cells, which had a higher ability to hydrolyze AMP and expressed CD73 mRNA and protein at higher levels. In addition, adenosine induced an increase in proliferation and migration in PTC derived cells, whose effect was blocked by APCP, a non-hydrolysable ADP analogue, which is an inhibitor of CD73. Taken together, these results showed that thyroid follicular cells have a functional purinergic signaling. The higher expression of CD73 in PTC derived cells might favor the accumulation of extracellular adenosine in the tumor microenvironment, which could promote tumor progression. Therefore, as already shown for other tumors, the purinergic signaling should be considered a potential target for thyroid cancer management and treatment.

No abstract

Carbapenems show recognized instability in aqueous solutions; therefore some care must be taken in their handling and preparation and their use in the hospital environment. The stability and degradation products of imipenem were investigated from conditions that simulate its clinical use. For this, a simple stability‐indicating method by HPLC‐DAD was validated with a focus on the quantitation of drug concentration remaining from infusion solutions (sodium chloride 0.9% and glucose 5%). The degradation products formed were identified by high‐resolution mass spectrometry (ESI‐Q‐TOF‐MS/MS), with detection of the [M + H]+ ions at m/z 318 (DP‐1), m/z 599 (DP‐2) and m/z 658 (DP‐3). The most probable elemental compositions were obtained with a high degree of confidence, where the error between the masses observed and calculated was 1.25 ppm for DP‐1, −0.33 ppm for DP‐2 and 1.82 ppm for DP‐3. The DP‐1 degradation product resulted from cleavage of the β‐lactam ring; DP‐2 corresponded to the drug dimer; and DP‐3 was generated from the interaction between imipenem and cilastatin. The proposed method provides a safe and reliable alternative for the quantitation of imipenem, and the stability data obtained by ESI‐Q‐TOF help in understanding the drug behavior under the conditions of clinical use.

Gostaria de agradecer a todas as pessoas que contribuíram para a concretização deste trabalho. Foram muitos amigos e que talvez nem imaginem a importância de cada um nas várias etapas deste trabalho. Àquelas pessoas que me foram fundamentais, deixo um agradecimento muito especial: Ao meu marido Ciro, pelo seu imenso amor, doação e paciência. Aos meus pais, Edmundo e Margarete, exemplos muito fortes de superação, já que tiveram a coragem de começar uma nova vida neste nosso Brasil. Ao meu orientador Prof. Renato Najjar, por acreditar em mim, pelas valiosas discussões, por estar sempre presente, me dando muita liberdade no planejamento dos meus experimentos e pelo exemplo de conduta profissional. Ao meu co-orientador Prof. Roberto F. de Souza, que vem me orientando desde os meus tempos de iniciação científica até os dias de hoje, com contribuições valiosas ao trabalho aqui apresentado e à minha formação científica. Ao Dr. Szulin Ber Zyngier, que tantas horas dedicou para me ensmar, com simplicidade, uma fração dos seus conhecimentos na área biológica, disposição para discussão dos resultados e disponibilidade do laboratório para os ensaios realizados neste trabalho. À minha filha Julia, que veio ao mundo para me ensinar a dar o devido valor a cada coisa e de me amar, incondicionalmente. À minha irmã Marilyn, que muito me ajuda, mesmo que às vezes eu não saiba transmitir o devido reconhecimento. Às minhas grandes amigas Rosane, Cláudia, V anusa e Mônica, de todas as horas (não caberia aqui tudo o que eu gostaria de falar). Às minhas amigas Simone Londero e Roseméri que tão carinhosamente me acolheram em suas casas e também junto à família.