Design of cancer-selective and nuclei-targeting cell-penetrating peptides and their characterization

Nowadays, cancer still remains one of the leading causes of death in the world. Therefore, cancer research is a present and central topic. Current drawbacks in cancer therapeutics are the lack of tumor specificity and the inefficient drug accumulation in cancer cells, resulting in non-specific agents that also affect healthy cells and thus their application provokes many side effects. Many possibilities for cancer cell-selective targeting of drugs are currently in focus. One includes the use of cell-penetrating peptides (CPPs), which are able to overcome the plasma membrane barrier and to transport various cargoes inside cells. Recently, it was shown for some CPPs, that they can specifically target cancer cells and therefore be used to promote the effective transport of anticancer drugs into various neoplastic cells. Furthermore, a certain intracellular targeting feature to various organelles was presented in the last years, which is important for the successful delivery of certain drugs to their point of action. This makes these amino acid sequences a promising research field in cancer treatment. In this study, the focus was set to the development and characterization of specific cancer-selective peptides that accumulate in the cell nuclei and can moreover be used to deliver various cargoes to cancer cells. The design of the CPPs was based on the C-terminal domain of the cationic antimicrobial peptide CAP18 (sC18), which was modified in various ways. For instance, it could be demonstrated that dimerization of the sequence and the N-terminally introduction of nuclear targeting sequences led to higher uptake rates of the CPP. Furthermore, the branched variant (sC18)2 exhibited a certain cancer cell-selectivity and was able to disrupt the neoplastic plasma membranes resulting in higher cytotoxicity. Next to this, the combination of sC18 with N50 and NrTP - two sequences that specifically target the cell nuclei - are approving the intracellular trafficking into the cell nucleus in cancer cells. Furthermore, an application as drug delivery system in breast cancer cells was elucidated

Event-Based Modelling of Ecological Systems With Asynchronous Cellular Automata

In this article, we give an example for the modelling of ecological systems with cellular automata based on the description of cell's behaviour by Petri nets. Petri nets offer a formal modelling technique with event--based, concurrent, asynchronous state changes where graphical symbols are used for the description of states resp. state changes. This allows the formal description of cellular automata with asynchronous cells' behaviour within one synchronous time phase of the automaton; i. e., within one time phase of the whole automaton, many asynchronous `mini-steps' of cells can appear. This can be used e. g. to model moving individuals that cross an arbitrary number of cells within one time phase. By this attempt, a large class of individual--oriented models can be defined in a more abstract and formal manner than it can be done by computer simulation programs. Since Petri nets allow a graphical representation of the modelled cells' behaviour, interactions, dependencies or cause--eff..

Design and biological characterization of novel cell-penetrating peptides preferentially targeting cell nuclei and subnuclear regions

Within this study, we report about the design and biological characterization of novel cell-penetrating peptides (CPPs) with selective suborganelle-targeting properties. The nuclear localization sequence N50, as well as the nucleoli-targeting sequence NrTP, respectively, were fused to a shortened version of the cell-penetrating peptide sC18. We examined cellular uptake, subcellular fate and cytotoxicity of these novel peptides, N50-sC18* and NrTP-sC18*, and found that they are nontoxic up to a concentration of 50 or 100 µM depending on the cell lines used. Moreover, detailed cellular uptake studies revealed that both peptides enter cells via energy-independent uptake, although endocytotic processes cannot completely excluded. However, initial drug delivery studies demonstrated the high versatility of these new peptides as efficient transport vectors targeting specifically nuclei and nucleoli. In future, they could be further explored as parts of newly created peptide–drug conjugates

Characterization of a Cell-Penetrating Peptide with Potential Anticancer Activity

Cell-penetrating peptides (CPPs) are still an interesting and viable alternative for drug delivery applications. CPPs contain considerably high amounts of positively charged amino acids, imparting them with cationic character. Tumor cells are characterized by an enhanced anionic nature of their membrane surface, a property that could be used by CPPs to target these cells. We recently identified a branched CPP that displays a high internalization capacity while exhibiting selectivity for certain tumor cell types. In this study we elucidated this observation in greater detail by investigating the underlying mechanism behind the cellular uptake of this peptide. An additional cytotoxicity screen against several cancer cell lines indeed demonstrates high cytotoxic activity against cancer cells over normal fibroblasts. Furthermore, we show that this feature can be used for delivering the anticancer drug actinomycinD with high efficiency in the MCF-7 cancer cell line

Impact of a preceding radiotherapy on the outcome of immune checkpoint inhibition in metastatic melanoma: a multicenter retrospective cohort study of the DeCOG

Background Immune checkpoint inhibition (ICI) is an essential treatment option in melanoma. Its outcome may be improved by a preceding radiation of metastases. This study aimed to investigate the impact of a preceding radiotherapy on the clinical outcome of ICI treatment. Methods This multicenter retrospective cohort study included patients who received anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) or anti-programmed cell death protein 1 (PD-1) ICI with or without preceding radiotherapy for unresectable metastatic melanoma. ICI therapy outcome was measured as best overall response (BOR), progression-free (PFS) and overall survival (OS). Response and survival analyses were adjusted for confounders identified by directed acyclic graphs. Adjusted survival curves were calculated using inverse probability treatment weighting. Results 835 patients who received ICI (anti-CTLA-4, n=596; anti-PD-1, n=239) at 16 centers were analyzed, whereof 235 received a preceding radiotherapy of metastatic lesions in stage IV disease. The most frequent organ sites irradiated prior to ICI therapy were brain (51.1%), lymph nodes (17.9%) and bone (17.9%). After multivariable adjustment for confounders, no relevant differences in ICI therapy outcome were observed between cohorts with and without preceding radiotherapy. BOR was 8.7% vs 13.0% for anti-CTLA-4 (adjusted relative risk (RR)=1.47; 95% CI=0.81 to 2.65; p=0.20), and 16.5% vs 25.3% for anti-PD-1 (RR=0.93; 95% CI=0.49 to 1.77; p=0.82). Survival probabilities were similar for cohorts with and without preceding radiotherapy, for anti-CTLA-4 (PFS, adjusted HR=1.02, 95% CI=0.86 to 1.25, p=0.74; OS, HR=1.08, 95% CI=0.81 to 1.44, p=0.61) and for anti-PD-1 (PFS, HR=0.84, 95% CI=0.57 to 1.26, p=0.41; OS, HR=0.73, 95% CI=0.43 to 1.25, p=0.26). Patients who received radiation last before ICI (n=137) revealed no better survival than those who had one or more treatment lines between radiation and start of ICI (n=86). In 223 patients with brain metastases, we found no relevant survival differences on ICI with and without preceding radiotherapy. Conclusions This study detected no evidence for a relevant favorable impact of a preceding radiotherapy on anti-CTLA-4 or anti-PD-1 ICI treatment outcome in metastatic melanoma