Diatoms are an important class of unicellular algae that produce bioactive polyunsaturated aldehydes (PUAs) that induce abortions or malformations in the offspring of invertebrates exposed to them during gestation. Here we compare the effects of the PUAs 2-trans,4-trans-decadienal (DD), 2-trans,4-trans-octadienal (OD) and 2-trans,4-trans-heptadienal (HD) on the adenocarcinoma cell lines lung A549 and colon COLO 205, and the normal lung/brunch epithelial BEAS-2B cell line. Using the viability MTT/Trypan blue assays, we show that PUAs have a toxic effect on both A549 and COLO 205 tumor cells but not BEAS-2B normal cells. DD was the strongest of the three PUAs tested, at all time-intervals considered, but HD was as strong as DD after 48 h. OD was the least active of the three PUAs. The effect of the three PUAs was somewhat stronger for A549 cells. We therefore studied the death signaling pathway activated in A549 showing that cells treated with DD activated Tumor Necrosis Factor Receptor 1 (TNFR1) and Fas Associated Death Domain (FADD) leading to necroptosis via caspase-3 without activating the survival pathway Receptor-Interacting Protein (RIP). The TNFR1/FADD/caspase pathway was also observed with OD, but only after 48 h. This was the only PUA that activated RIP, consistent with the finding that OD causes less damage to the cell compared to DD and HD. In contrast, cells treated with HD activated the Fas/FADD/caspase pathway. This is the first report that PUAs activate an extrinsic apoptotic machinery in contrast to other anticancer drugs that promote an intrinsic death pathway, without affecting the viability of normal cells from the same tissue type. These findings have interesting implications also from the ecological viewpoint considering that HD is one of the most common PUAs produced by diatoms.

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Abstract. Survivin (SVV) is a protein that belongs to the inhibitor of apoptosis proteins (IAP) family and is involved in the G2/M phase progression of the cell cycle as a spindle-associated molecule. The biological features of this protein are well documented and its activity appears to be involved in mitochondria-dependent and -independent antiapoptotic pathways. Overexpression of SVV at the transcriptional and translational level has been associated with cancer, a multifactorial disorder in which the occurrence of a -31G to C polymorphism in the promoter region may significantly contribute to the development of this pathology. To verify this hypothesis, the occurrence of a single nucleotide polymorphism (SNP) in cis-acting cell cycle-dependent elements (CDEs) and in cell cycle homology regions (CHRs) of the survivin TATA-less promoter was investigated. A total of 23 oral squamous cell carcinoma (OSCC) cell lines and normal epithelium-derived normal human epidermal keratinocyte (NHEK) cell lines were analyzed by RFLP and direct DNA sequencing of their promoter region. Furthermore, survivin expression at the transcriptional and translational levels was evaluated in these cells by RT-PCR and Western blotting, respectively. The findings indicate that the presence of a G or C allele is not directly correlated to survivin expression, at the mRNA or at the protein level, at least in the OSCC lines analyzed in this study. IntroductionSurvivin was discovered by Altieri's group in 1997 (1). The gene coding for survivin was also identified by the same group during a search for the unknown receptor (effector cell protease receptor, epr-1) of blood coagulation factor Xa (2).Survivin is an essential protein that acts as a passenger protein involved in cell division, and belongs to the inhibitor of apoptosis proteins (IAP) family (1-3). Its antiapoptotic zinc-binding domain, baculoviral IAP repeat (BIR), was identified for the first time in a baculoviral protein (4). The human locus is indicated as BIR-containing 5 (BIRC5) and lies on the long arm of chromosome 17 in the telomeric region 25 (17q25) (5). This locus is the source of numerous variant transcripts (survivin, survivin-1α, survivin-2α, survivin-2β, 3β and Δ3), where survivin is the most abundantly transcribed and translated variant in a 142 amino acid-long polypeptide, whereas the minor variants are poorly expressed and investigated (6-9). Furthermore, the occurrence of a natural survivin antisense strand, defined as a distinct gene, codifying for a hypothetical receptor of Xa coagulation factor, epr-1, is well documented (2-10). All of the splicing isoforms share a common promoter belonging to the housekeeping family promoter that is known to be TATA-less and CpG-rich (11).The survivin promoter region was investigated and the minimal promoter region, detected within the proximal -220 nt of the human survivin gene, was found to contain numerous Sp1 sites, three cell cycle-dependent elements (CDEs) and one cell cycle homology region (CHR) implicated in G1 transcrip...