Cadherin-6 promotes EMT and cancer metastasis by restraining autophagy.

The transdifferentiation of epithelial cells toward a mesenchymal condition (EMT) is a complex process that allows tumor cells to migrate to ectopic sites. Cadherins are not just structural proteins, but they act as sensors of the surrounding microenvironment and as signaling centers for cellular pathways. However, the molecular mechanisms underlying these signaling functions remain poorly characterized. Cadherin-6 (CDH6) is a type 2 cadherin, which drives EMT during embryonic development and it is aberrantly re-activated in cancer. We recently showed that CDH6 is a TGFß target and an EMT marker in thyroid cancer, suggesting a role for this protein in the progression of this type of tumor. Papillary thyroid carcinomas (PTCs) are usually indolent lesions. However, metastatic spreading occurs in about 5% of the cases. The identification of molecular markers that could early predict the metastatic potential of these lesions would be strategic to design more tailored approaches and reduce patients overtreatment. In this work, we assessed the role of CDH6 in the metastatic progression of thyroid cancer. We showed that loss of CDH6 expression profoundly changes cellular architecture, alters the inter-cellular interaction modalities and attenuates EMT features in thyroid cancer cells. Using a yeast two-hybrid screening approach, based on a thyroid cancer patients library, we showed that CDH6 directly interacts with GABARAP, BNIP3 and BNIP3L, and that through these interactions CDH6 restrains autophagy and promotes re-organization of mitochondrial network through a DRP1-mediated mechanism. Analysis of the LIR domains suggests that the interaction with the autophagic machinery may be a common feature of many cadherin family members. Finally, the analysis of CDH6 expression in a unique cohort of human PTCs showed that CDH6 expression marks specifically EMT cells. and it is strongly associated with metastatic behavior and worse outcome of PTCs.

Molecular markers for the characterization of Brazilian Cercospora caricis isolates.

Cercospora caricis is of interest as a potential mycoherbicide for control of purple nutsedge, Cyperus rotundus, which is considered to be the world's worst weed. The genetic variation of a collection of Brazilian Ce. caricis isolated from Cy. rotundus was analyzed by using RAPD, RFLP with a telomeric probe, [TTAGGG]18 and sequencing of the ITS1-5.8S-ITS2 regions of the ribosomal RNA gene. The Brazilian isolates were also compared with a Ce. caricis isolate from Florida, USA and with some other Cercospora species. A cluster of isolates from the Brazilian cerrado region was identified showing high genetic similarity. In contrast, isolates originating in other geographic regions of Brazil were less than 50% and 25% related to the former group according to similarity estimates produced from RAPD and telomeric RFLP analyses respectively. ITS sequence analysis did not support taxonomic division of the Brazilian strains, but did confirm the distant relatedness of these strains to the Ce. caricis isolate from Florida. The data indicate a need for an extensive molecular survey of Cercospora species associated with the Cyperaceae.

Beauveria bassiana (Hyphomycetes) as a possible agent for biological control of Chagas disease vectors.

Beauveria bassiana (Balsamo) Vuillemin (isolate CG306) was tested on 3rd instars of 9 Triatoma spp., 4 Rhodnius spp., 2 Panstrongylus spp. and Dipetalogaster maxima (Uhler) at 25 degrees C and 50% RH. Quantitative sporulation of the fungus on cadavers was studied at 25 degrees C and 97% RH. Mortality, estimates of survival time, and conidial production on cadavers differed significantly among the genera and species tested. Panstrongylus herreri Wygodzinsky, Dipetalogaster maxima, Triatoma picturata Usinger, Rhodnius robustus Larrousse, Rhodnius prolixus Stål, Triatoma infestans (Klug), and Triatoma brasiliensis Neiva were most susceptible to fungal infection. Most conidia per cadaver were produced on Triatoma williami Galvão, Souza & Lima and Triatoma lecticularia (Stål). Results indicate that B. bassiana (CG306) might be a candidate for control of important or potential vectors of Trypanosoma cruzi using the fungus as a bioinsecticide.

Selection of Beauveria bassiana and Metarhizium anisopliae isolates to control Triatoma infestans.

Twenty three isolates of Beauveria bassiana and 13 isolates of Metarhizium anisopliae were tested on third instar nymphs of Triatoma infestans, a serious vector of Chagas disease. Pathogenicity tests at saturated humidity showed that this insect is very susceptible to fungal infection. At lower relative humidity (50%), conditions expected in the vector microhabitat, virulence was significantly different among isolates. Cumulative mortality 15 days after treatment varied from 17.5 to 97.5%, and estimates of 50% survival time varied from 6 to 11 days. Maintaining lower relative humidity, four B. bassiana and two M. anisopliae isolates were selected for analysis of virulence at different conidial concentrations and temperatures. Lethal concentrations sufficient to kill 50% of insects (LC50) varied from 7.1 x 10(5) to 4.3 x 10(6) conidia/ml, for a B. bassiana isolate (CG 14) and a M. anisopliae isolate (CG 491) respectively. Most isolates, particularly B. bassiana isolates CG 24 and CG 306, proved to be more virulent at 25 and 30 degrees C, compared to 15 and 20 degrees C. The differential virulence at 50% humidity observed among some B. bassiana isolates was not correlated to phenetic groups in cluster analysis of RAPD markers. In fact, the B. bassiana isolates analyzed presented a high homogeneity (> 73% similarity).