Analysis of Marker-Defined HNSCC Subpopulations Reveals a Dynamic Regulation of Tumor Initiating Properties

Head and neck squamous carcinoma (HNSCC) tumors carry dismal long-term prognosis and the role of tumor initiating cells (TICs) in this cancer is unclear. We investigated in HNSCC xenografts whether specific tumor subpopulations contributed to tumor growth. We used a CFSE-based label retentions assay, CD49f (α6-integrin) surface levels and aldehyde dehydrogenase (ALDH) activity to profile HNSCC subpopulations. The tumorigenic potential of marker-positive and -negative subpopulations was tested in nude (Balb/c nu/nu) and NSG (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ) mice and chicken embryo chorioallantoic membrane (CAM) assays. Here we identified in HEp3, SQ20b and FaDu HNSCC xenografts a subpopulation of G0/G1-arrested slow-cycling CD49fhigh/ALDH1A1high/H3K4/K27me3low subpopulation (CD49f+) of tumor cells. A strikingly similar CD49fhigh/H3K27me3low subpopulation is also present in primary human HNSCC tumors and metastases. While only sorted CD49fhigh/ALDHhigh, label retaining cells (LRC) proliferated immediately in vivo, with time the CD49flow/ALDHlow, non-LRC (NLRC) tumor cell subpopulations were also able to regain tumorigenic capacity; this was linked to restoration of CD49fhigh/ALDHhigh, label retaining cells. In addition, CD49f is required for HEp3 cell tumorigenicity and to maintain low levels of H3K4/K27me3. CD49f+ cells also displayed reduced expression of the histone-lysine N-methyltransferase EZH2 and ERK1/2phosphorylation. This suggests that although transiently quiescent, their unique chromatin structure is poised for rapid transcriptional activation. CD49f− cells can “reprogram” and also achieve this state eventually. We propose that in HNSCC tumors, epigenetic mechanisms likely driven by CD49f signaling dynamically regulate HNSCC xenograft phenotypic heterogeneity. This allows multiple tumor cell subpopulations to drive tumor growth suggesting that their dynamic nature renders them a “moving target” and their eradication might require more persistent strategies

O processo qualitativo de pesquisa mediando a transformação da realidade: uma contribuição para o trabalho de equipe em educação em saúde The qualitative process of research mediating the transformation of reality: a contribution to team work in health education

Este artigo apresenta a experiência da aplicação de um método qualitativo de pesquisa que, além da compreensão das práticas de educação em saúde desenvolvidas por uma equipe de saúde de um ambulatório-escola, proporcionou um processo educativo com base na reflexão crítica dos resultados do estudo, com os próprios sujeitos da pesquisa. Essa experiência foi desenvolvida com dezenove profissionais de saúde do Serviço de Assistência Integrada à Saúde de Tubarão, Santa Catarina. O processo de pesquisa ocorreu em quatro momentos. Momento 1: caracterizado como momento inicial de interação com os sujeitos do estudo - escuta e diálogo - para a primeira fase de levantamento dos dados. Momento 2: momento particular reflexivo-criativo do pesquisador, representando a primeira fase do processo de análise-reflexão-síntese dos dados. Momento 3: momento coletivo de interação e diálogo reflexivo com a equipe de saúde para discussão da realidade encontrada e descoberta de temas emergentes. Momento 4: momento particular do pesquisador para análise-reflexão-síntese da totalidade dos dados. Dessa prática educativa com a equipe de saúde emergiu o tema "A necessidade e a vontade de transcender para o contexto do cliente e as (im)possibilidades de romper com os atuais padrões das práticas em saúde", cuja síntese final gerou estratégias de mudanças naquele Serviço.<br>This paper presents the experience of applying a qualitative survey method that offers an understanding of the educational healthcare practices developed by a healthcare group working at a teaching out-patient clinic. This method also led the survey subjects through an educational process based on critical thinking about the findings of the survey. This experiment was conducted with nineteen healthcare practitioners at the Tubarão Integrated HealthCare Unit in Santa Catarina State. The survey was carried out in four phases. Phase 1: initial interaction with the participants in the study (listening and dialog) for the first data collection phase. Phase 2: private time for the researcher to think creatively as a first step in the process of analyzing, considering, and summarizing the data. Phase 3: collective interaction and reflective dialog with the healthcare group, discussing the situations encountered and exploring emerging topics. Phase 4: private time for the researcher to analyze, consider and summarize all data. This educational practice with the healthcare group resulted in the appearance of the topic: "The need and the will to transcend to the client's context and the (im)possibilities of breaking away from current patterns of healthcare practices", prompting suggestions for strategic changes in the Unit