title: Insights into the potential of picoplanktonic marine cyanobacteria strains for cancer therapies - Cytotoxic mechanisms against the RKO colon cancer cell line.
abstract: OBJECTIVE
  In this work, we analysed the potential of picoplanktonic marine cyanobacteria strains as a source of anticancer compounds by elucidating the cytotoxic mechanisms of an ethyl acetate fraction of Cyanobium sp. (LEGE06113) and the Synechocystis salina (LEGE06155) on the RKO colon adenocarcinoma cell line.
  
  
  METHODS
  Cytotoxicity was analysed by MTT. Effects on cells were evaluated by mRNA expression of cell cycle and apoptotic genes, flow cytometry (cell cycle), qualitative and quantitative fluorescence microscopy (apoptosis), and quantitative proteomics.
  
  
  RESULTS
  IC50 values were 27.01 and 8.03 μg/ml for Cyanobium sp., and 37.71 and 17.17 μg/ml for Synechocystis salina, after 24 h and 48 h, respectively. Exposure to the Cyanobium sp. fraction increased 2.5 fold BCL-2 mRNA expression (p < 0.05), and altered proteins (13, p < 0.05) belonged to apoptosis (PSMA5, PSMA7, TPT1, UBE2K), cell cycle (EIF4E, PCNA), cellular metabolism (AHSG, GLO1, ATP5H, HSP90AB1, NME1, HNRNPC) and cell structure (KRT10). Exposure to the Synechocystis salina fraction decreased 2fold CCNB1 mRNA expression (p < 0.05). Accordingly, flow cytometry demonstrated a decrease of cells in the G0/G1 and S phase (p < 0.05), indicating a cell cycle arrest at the G2/M transition. Fluorescence microscopy confirmed a higher level of apoptosis compared to the solvent control group (p < 0.01). Altered proteins (6, p < 0.05) belonged to apoptosis (HSPD1, UBE2K), protein metabolism (PKM, PDIA3) and cell structure (KRT10, KRT1).
  
  
  CONCLUSIONS
  Since induction of cytotoxicity is a very broad parameter, the study demonstrates the potential of picocyanobacteria to produce bioactive compounds that target cancer cells via different molecular mechanisms.
authors.affiliation: Interdisciplinary Center of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, 4050-123, Porto, Portugal. Electronic address: freitas.srf.09@gmail.com.
authors.forename: Sara
authors.initials: S
authors.lastname: Freitas
authors.affiliation: Interdisciplinary Center of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, 4050-123, Porto, Portugal; Health and Environmental Research Center (CISA), School of Allied Health Sciences of Porto, Polytechnic Porto, Rua Valente Perfeito 322, 4400-330, Vila Nova de Gaia, Portugal; Department of Biology Faculty of Sciences, University of Porto, Rua do Campo Alegre, Edifício FC4, 4169-007, Porto, Portugal; Institute for Molecular and Cell Biology (IBMC), University of Porto, Rua do Campo Alegre 823, 4150-180, Porto, Portugal. Electronic address: mrm@estsp.ipp.pt.
authors.forename: Rosário
authors.initials: R
authors.lastname: Martins
authors.affiliation: Interdisciplinary Center of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, 4050-123, Porto, Portugal. Electronic address: amoclclix@gmail.com.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Campos
authors.affiliation: Interdisciplinary Center of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, 4050-123, Porto, Portugal. Electronic address: joana_passo@hotmail.com.
authors.forename: Joana
authors.initials: J
authors.lastname: Azevedo
authors.affiliation: i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IPATIMUP-Institute of Molecular Pathology and Immunology of the University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal; Faculty of Medicine, University of Porto, Al. Prof. Hernâni Monteiro, 4200-319, Porto, Portugal. Electronic address: hosorio@ipatimup.pt.
authors.forename: Hugo
authors.initials: H
authors.lastname: Osório
authors.affiliation: Interdisciplinary Center of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, 4050-123, Porto, Portugal. Electronic address: costa.anamarg@gmail.com.
authors.forename: Margarida
authors.initials: M
authors.lastname: Costa
authors.affiliation: Health and Environmental Research Center (CISA), School of Allied Health Sciences of Porto, Polytechnic Porto, Rua Valente Perfeito 322, 4400-330, Vila Nova de Gaia, Portugal. Electronic address: pgb@estsp.ipp.pt.
authors.forename: Piedade
authors.initials: P
authors.lastname: Barros
authors.affiliation: Interdisciplinary Center of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, 4050-123, Porto, Portugal; Department of Biology Faculty of Sciences, University of Porto, Rua do Campo Alegre, Edifício FC4, 4169-007, Porto, Portugal. Electronic address: vmvascon@fc.up.pt.
authors.forename: Vitor
authors.initials: V
authors.lastname: Vasconcelos
authors.affiliation: Interdisciplinary Center of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, 4050-123, Porto, Portugal. Electronic address: rurbatzka@ciimar.up.pt.
authors.forename: Ralph
authors.initials: R
authors.lastname: Urbatzka
mesh_terms: D045744:Cell Line, Tumor; D000458:Cyanobacteria / Q000502:physiology*; D006801:Humans; D008386:Marine Biology; D010933:Plankton / Q000502:physiology*; D000090324:Tumor Protein, Translationally-Controlled 1
keywords: Anticancer potential; Apoptosis; Cell cycle; Picocyanobacteria; Proteomics