Rare actinobacteria isolated from the hypersaline Ojo de Liebre Lagoon as a source of novel bioactive compounds with biotechnological potential.

The Ojo de Liebre Lagoon is a Marine Protected Area that lies within a UNESCO World Heritage Site and is a critical habitat for important migratory species such as the grey whale and bird species. Unique hypersaline environments, such as the Ojo de Liebre Lagoon, are underexplored in terms of their bacterial and chemical diversity, representing a potential source for new bioactive compounds with pharmacological properties. Actinobacteria are one of the most diverse and prolific taxonomic bacterial groups in terms of marine bioactive compounds. This study aimed to identify the culturable actinobacterial community inhabiting the Lagoon, as well as to test their potential as new sources of anticancer compounds with pharmacological potential. A selective isolation approach focused on spore-forming bacteria from 40 sediment samples generated a culture collection of 64 strains. The 16S rRNA gene analyses identified three phyla in this study, the Actinobacteria, Firmicutes and Proteobacteria, where the phylum Actinobacteria dominated (57%) the microbial community profiles. Within the Actinobacteria, nine different genera were isolated including the Actinomadura, Micromonospora, Nocardiopsis, Plantactinospora and Streptomyces sp. We observed seasonal differences on actinobacteria recovery. For instance, Micromonospora strains were recovered during the four sampling seasons, while Arthrobacter and Pseudokineococcus were only isolated in February 2018, and Blastococcus, Rhodococcus and Streptomyces were uniquely isolated in June 2018. Ethyl acetate crude extracts derived from actinobacterial cultures were generated and screened for cytotoxic activity against six cancer cell lines. Strains showed promising low percentages of viability on lung (H1299), cervical (SiHa), colon (Caco-2) and liver (HepG2) cancer lines. Molecular networking results suggest many of the metabolites produced by these strains are unknown and they might harbour novel chemistry. Our results showed the Ojo de Liebre Lagoon is a novel source for isolating diverse marine actinobacteria which produce promising bioactive compounds for potential biotechnological use as anticancer agents.

Smart Nanoformulation Based on Stimuli-Responsive Nanogels and Curcumin: Promising Therapy against Colon Cancer.

Curcumin (CUR) has gained much attention for its widely reported anticancer effect; however, its clinical use is restricted due to its low water solubility and, consequently, its poor bioavailability. Here, we report on the use of a nanoformulation of CUR with cationic nanogels for colon cancer therapy. Cationic stimuli-sensitive nanogels were prepared using a scale-up polymerization methodology based on surfactant-free emulsion polymerization of N,N'-diethylaminoethyl methacrylate (DEAEM) and poly(ethyleneglycol) methacrylate (PEGMA). The obtained nanogels showed a homogeneous size distribution (from 51 to 162 nm, polydispersity index (PDI) < 0.138) and exhibited a spherical form and core-shell morphology as confirmed by dynamic light scattering and electron microscopy, respectively. Nanogels were responsive to and degradable by variations of pH, temperature, or the redox environment, depending on the cross-linker used in the synthesis. Nanogels cross-linked with bis(acryloyl)cystamine incubated in a buffer (pH 7.4) containing 3 mM glutathione degraded in 60 min, while nanogels cross-linked with a divinylacetal cross-linker degraded in 10 min (pH ≤ 6). Nanoformulations of nanogels with CUR were stable as tested up to 30 days at physiological conditions. In vitro studies of the human colon cancer cell line (HCT-116) showed a synergistic effect of CUR and the degradable nanogels. Further, in vivo acute cytotoxicity tests of empty nanogels in mice demonstrate their potential as CUR nanocarriers for colon-anticancer therapies.

Proapoptotic Index Evaluation of Two Synthetic Peptides Derived from the Coneshell Californiconus californicus in Lung Cancer Cell Line H1299.

Lung cancer is one of the most common types of cancer, accounting for approximately 15% of all cancer cases worldwide. Apoptosis is the dominant defense mechanism against tumor development. The balance between pro- and antiapoptotic members of the Bcl-2 protein family can determine cellular fate. The venom of predatory marine snails Conus is estimated to have 100-400 toxins called conotoxins. The family of α-conotoxins is known to consist of selective antagonists of nicotinic acetylcholine receptors (nAChRs). Lung cancer cells overexpress several subunits of nAChRs and are considered as an excellent target for new anticancer drugs. We compared the cytotoxic effect of two synthetic peptides derived from Californiconus californicus, Cal14.1a, and Cal14.1b, which only differ by one amino acid in their sequence, and compared their proapoptotic balance by Bax and Bcl-2 mRNA expression. We determined the caspase-3 and -7 activation to demonstrate apoptosis induction. Results showed that Cal14.1a induces a high Bax/Bcl-2 ratio in H1299 (lung cancer cells). Although Cal14.1b has a cytotoxic effect on H1299 cells, reducing cell viability by 30%, it does not increase the Bax/Bcl-2 ratio, which could be explained by the Glu in the 15th residue, which is crucial for the ability of Cal14.1a to induce apoptosis.

Apoptosis Activation in Human Lung Cancer Cell Lines by a Novel Synthetic Peptide Derived from Conus californicus Venom.

Lung cancer is one of the most common types of cancer in men and women and a leading cause of death worldwide resulting in more than one million deaths per year. The venom of marine snails Conus contains up to 200 pharmacologically active compounds that target several receptors in the cell membrane. Due to their diversity and specific binding properties, Conus toxins hold great potential as source of new drugs against cancer. We analyzed the cytotoxic effect of a 17-amino acid synthetic peptide (s-cal14.1a) that is based on a native toxin (cal14.1a) isolated from the sea snail Conus californicus. Cytotoxicity studies in four lung cancer cell lines were complemented with measurement of gene expression of apoptosis-related proteins Bcl-2, BAX and the pro-survival proteins NFκB-1 and COX-2, as well as quantification of caspase activity. Our results showed that H1299 and H1437 cell lines treated with s-call4.1a had decreased cell viability, activated caspases, and reduced expression of the pro-survival protein NFκB-1. To our knowledge, this is the first report describing activation of apoptosis in human lung cancer cell lines by s-cal14.1a and we offer insight into the possible mechanism of action.