Scale-down studies for assessing the impact of different stress parameters on growth and product quality during animal cell culture

Two series of reproducible fed-batch bench scale cultures have been undertaken, one series simulating the impact of spatial variations in pH and nutrients as found at commercial scale on performance, the other, the impact of fluid dynamic stresses associated with agitation. The first was unsuccessful because, somewhat surprisingly, the use of a peristaltic pump to circulate cells and medium through different spatial environments always led to a similar reduction in culture time and resulting product titre compared to uncirculated controls. This fall was sufficient to essentially mask other effects. In the second, even at maximum specific energy dissipation rates up to ~160 times > with laminar extensional flow and ~25 times > with turbulent flow compared to typical commercial conditions, no significant effects were observed on cell growth and viability. Most importantly, in all of the cases studied, product quality was unaffected compared to controls. In addition, it is suggested that because of the possibility of cell line specific behaviour and the relationship between damage to entities and the Kolmogorov scale of turbulence, sensitivity to fluid dynamic stresses is best studied in turbulent bench scale bioreactors. © 2013 The Institution of Chemical Engineers

Local Structural Preferences of Calpastatin, the Intrinsically Unstructured Protein Inhibitor of Calpain

Calpain, the calcium-activated intracellular cysteine protease, is under the tight control of its intrinsically unstructured inhibitor, calpastatin. Understanding how potent inhibition by calpastatin can be reconciled with its unstructured nature provides deeper insight into calpain function and a more general understanding of how proteins devoid of a well-defined structure carry out their function. To this end, we performed a full NMR assignment of hCSD1 to characterize it in its solution state. Secondary chemical shift values and NMR relaxation data, R1, R2, and hetero-NOE, as well as spectral density function analysis have shown that conserved regions of calpastatin, subdomains A and C, which are responsible for calcium-dependent anchoring of the inhibitor to the enzyme, preferentially sample partially helical backbone conformations of a reduced flexibility. Moreover, the linker regions between subdomains are more flexible with no structural preference. The primary determinant of calpain inhibition, subdomain B, also has a non-fully random conformational preference, resembling a β-turn structure also ascertained by prior studies of a 27-residue peptide encompassing the inhibitory region. This local structural preference is also confirmed by a deviation in chemical shift values between full-length calpastatin domain 1 and a truncated construct cut in the middle of subdomain B. At the C-terminal end of the molecule, a nascent helical region was found, which in contrast to the overall structural properties of the molecule may indicate a previously unknown functional region. Overall, these observations provide further evidence that supports previous suggestions that intrinsically unstructured proteins use preformed structural elements in efficient partner recognition

Evaluation of the Antiproliferative Activity of Diterpene Isonitriles from the Sponge <i>Pseudoaxinella flava</i> in Apoptosis-Sensitive and Apoptosis-Resistant Cancer Cell Lines

One new (1) and three known (2–4) isonitrile diterpenes, isolated from the Caribbean sponge Pseudoaxinella flava, were assayed in human cancer cell lines in vitro using an MTT colorimetric assay and quantitative videomicroscopy. Compounds 1–4 displayed activity for human PC3 prostate apoptosis-sensitive cancer cell lines. Compounds 3 and 4 demonstrated similar growth inhibitory effects for three apoptosis-sensitive and three apoptosis-resistant cancer cell lines. Quantitative videomicroscopy analysis revealed that compounds 1 and 2 exerted their activity through cytotoxic effects, and compounds 3 and 4 through cytostatic effects. These results identify marine diterpene isonitriles as potential lead compounds for anticancer drug discovery

Synthesis and Cytotoxicity on Sensitive and Doxorubicin-Resistant Cell Lines of New Pyrrolo[2,1-<i>c</i>][1,4]benzodiazepines Related to Anthramycin

A new 7,8-methylenedioxy analogue (4) of (+)-porothramycin B (2) and its water-soluble sodium bisulfite derivative (15) have been synthesized in high yields and have been shown to exhibit high cytotoxic activities against several tumor cell lines. The new pyrrolo[2,1-c][1,4]benzodiazepine 4 was as effective against the resistant cell lines as against the doxorubicin-sensitive cell lines tested

Cardenolides from <i>Pergularia tomentosa</i> Display Cytotoxic Activity Resulting from Their Potent Inhibition of Na⁺/K⁺-ATPase

Two new cardenolide glycosides (1 and 2), along with six known cardenolide glycosides (3−8), have been isolated from the roots of Pergularia tomentosa. In order to investigate their potential anticancer activity, these compounds were tested in an in vitro growth inhibitory assay (a MTT colorimetric assay), including six different human cancer cell lines, and for their ability to inhibit Na+/K+-ATPase activity, in addition to the morphologic changes induced in human cancer cell lines (using computer-assisted phase-contrast microscopy). The data revealed that these cardenolides displayed marked cytotoxic activity. The results obtained suggest that structural characteristics of the cardenolides studied, with the A/B rings of the steroidal skeleton trans fused and containing a single sugar in a unique “dioxanoid” attachment, confer on them specific cytotoxic properties that are distinct from those displayed by classic cardenolides such as digoxin

Sequestered Fulvinol-Related Polyacetylenes in <i>Peltodoris atromaculata</i>

The Mediterranean dorid nudibranch <i>Peltodoris atromaculata</i> that had been collected while feeding on <i>Haliclona fulva</i> was shown to sequester long-chain fulvinol-like polyacetylene metabolites (compounds <b>2</b>–<b>5</b>) from the prey. They were isolated along with previously reported bromorenierins from the diethyl ether extracts of both the mollusk and the sponge. Their structures were elucidated by NMR spectroscopy and tandem FABMS analysis. Compound <b>5</b> exhibited in vitro growth inhibitory effects against the SKMEL-28 melanoma cell line

Structure–Activity Relationship Analysis of Bufadienolide-Induced in Vitro Growth Inhibitory Effects on Mouse and Human Cancer Cells

The in vitro growth inhibitory effects of 27 bufadienolides and eight degradation products, with two cardenolides (ouabain and digoxin) chosen as reference compounds, were analyzed by means of an MTT colorimetric assay in six human and two mouse cancer cell lines. A structure–activity analysis was then performed to highlight the most important substituents relating to the in vitro growth inhibitory activity of bufadienolides in cancer cells. Thus, the current study revealed that various bufadienolides, including gamabufotalin rhamnoside (<b>1a</b>), bufotalin (<b>2a</b>), and hellebrin (<b>3a</b>), displayed higher growth inhibitory activities for various human cancer cell lines when compared to ouabain and digoxin. Gamabufotalin rhamnoside (<b>1a</b>) was the only compound that displayed growth inhibitory effects of <1 μM in mouse cancer cells that expressed mutated forms of the Na⁺,K⁺-ATPase α-1 subunit. In addition, all genins and degradation products displayed weaker (if any) in vitro growth inhibitory effects on cancer cells when compared to their respective glycosylated homologue, with the exception of hellebrigenin (<b>3b</b>), which was as active as hellebrin (<b>3a</b>)

Rapid Structural Identification of Cytotoxic Bufadienolide Sulfates in Toad Venom from <i>Bufo melanosticus</i> by LC-DAD-MS^<i>n</i> and LC-SPE-NMR

Toad venom, namely, “Chansu” in China, has been widely used for the treatment of heart failure, sores, pains, and various cancers. Upon LC-MS analysis of the venom from Bufo melanosticus collected in Indonesia, new bufadienolide sulfates were identified. For a complete characterization, the MeOH extract of the toad venom from B. melanosticus was fractionated by preparative HPLC, and the structures of five new buadienolide sulfates (1−5) along with one new bufogenin (6) were rapidly elucidated on the basis of LC-DAD-MSn and LC-SPE-NMR data. The in vitro growth inhibitory activity of these six compounds along with hellebrin (positive control) has been assayed by means of the MTT colorimetric assay in four human and two mouse cancer cell lines. Compound 3 and hellebrin displayed similar and marked in vitro cytotoxicity

Galectin-Inhibitory Thiodigalactoside Ester Derivatives Have Antimigratory Effects in Cultured Lung and Prostate Cancer Cells

Aromatic 3,3′-diesters of thiodigalactoside were synthesized in a rapid three-step sequence from commercially available thiodigalactoside and evaluated as inhibitors of cancer- and immunity-related galectins. For each of galectins-1, -3, -7, and -9N-terminal domain, aromatic 3,3′-diesters of thiodigalactoside were found to have affinities in the low micromolar range, which represents a 7−70 fold enhancement over thiodigalactoside itself. No significant improvement was found for galectin-8 N-terminal domain. Two of the compounds were selected for testing in cell culture and were shown to have potent antimigratory effects on human PC-3 prostate and human A549 nonsmall-cell lung cancer cells

New Approach for the Preparation of Efficient DNA Cleaving Agents: Ditopic Copper−Platinum Complexes Based on 3-Clip-Phen and Cisplatin

The design and synthesis of new heterodinuclear DNA-targeting agents are described. The abilities of cisplatin and Cu(3-Clip-Phen) [Cu(1-(1,10-phenanthrolin-3-yloxy)-3-(1,10-phenanthrolin-8-yloxy)propan-2-amine)Cl2], an artificial DNA-cleaving agent, have been combined through their “covalent coupling”. This strategy has led to bifunctional complexes that are able to cleave the DNA in a double-stranded fashion in contrast to Cu(3-Clip-Phen) alone and have promising cytotoxicities compared to cisplatin in several cell lines