Translation in solid cancer: are size-based response criteria an anachronism?

The purpose of translation is the development of effective medicinal products based on validated science. A parallel objective is to obtain marketing authorization for the translated product. Unfortunately, in solid cancer, these two objectives are not mutually consistent as evidenced by the contrast between major advances in science and the continuing dismal record of pharmaceutical productivity. If the problem is unrelated to science, then the process of translation may require a closer examination, namely, the criteria for regulatory approval. This realization is important because, in this context, the objective of translation is regulatory approval, and science does not passively translate into useful medicinal products. Today, in solid cancer, response criteria related to tumor size are less useful than during the earlier cytotoxic drugs era; advanced imaging and biomarkers now allow for tracking of the natural history of the disease in the laboratory and the clinic. Also, it is difficult to infer clinical benefit from tumor shrinkage since it is rarely sustained. Accordingly, size-based response criteria may represent an anachronism relative to translation in solid cancer and it may be appropriate to align preclinical and clinical effort and shift the focus to local invasion and metastasis. The shift from a cancer cellcentric model to a stroma centric model offers novel opportunities not only to interupt the natural history of the disease, but also to rethink the relevance of outdated criteria of clinical response. Current evidence favors the opinion that, in solid cancer, a different, broader, and contextual approach may lead to interventions that could delay local invasion and metastasis. All elements supporting this shift, especially advanced imaging, are in place(AU)

No disponible

Translation in solid cancer: are size-based response criteria an anachronism?

The purpose of translation is the development of effective medicinal products based on validated science. A parallel objective is to obtain marketing authorization for the translated product. Unfortunately, in solid cancer, these two objectives are not mutually consistent as evidenced by the contrast between major advances in science and the continuing dismal record of pharmaceutical productivity. If the problem is unrelated to science, then the process of translation may require a closer examination, namely, the criteria for regulatory approval. This realization is important because, in this context, the objective of translation is regulatory approval, and science does not passively translate into useful medicinal products. Today, in solid cancer, response criteria related to tumor size are less useful than during the earlier cytotoxic drugs era; advanced imaging and biomarkers now allow for tracking of the natural history of the disease in the laboratory and the clinic. Also, it is difficult to infer clinical benefit from tumor shrinkage since it is rarely sustained. Accordingly, size-based response criteria may represent an anachronism relative to translation in solid cancer and it may be appropriate to align preclinical and clinical effort and shift the focus to local invasion and metastasis. The shift from a cancer cell-centric model to a stroma centric model offers novel opportunities not only to interupt the natural history of the disease, but also to rethink the relevance of outdated criteria of clinical response. Current evidence favors the opinion that, in solid cancer, a different, broader, and contextual approach may lead to interventions that could delay local invasion and metastasis. All elements supporting this shift, especially advanced imaging, are in place.

Dynamics and morphology of focal adhesions in complex 3D environment.

Focal adhesions are specific types of cellular adhesion structures through which both mechanical force and regulatory signals are transmitted. Recently, the existence of focal adhesions in 3D environment has been questioned. Using a unique life-like model of dermis-based matrix we analysed the presence of focal adhesions in a complex 3D environment. Although the dermis-based matrix constitutes a 3D environment, the interface of cell-to-matrix contacts on thick bundled fibres within this matrix resembles 2D conditions. We call this a quasi-2D situation. We suggest that the quasi-2D interface of cell-to-matrix contacts constituted in the dermis-based matrix is much closer to in tissue conditions than the meshed structure of mostly uniform thin fibres in the gel-based matrices. In agreement with our assumption, we found that the cell adhesion structures are formed by cells that invade the dermis-based matrix and that these structures are of similar size as focal adhesions formed on fibronectin-coated coverslips (2D). In both 2D situation and the dermis-based matrix, we observed comparable vinculin dynamics in focal adhesions and comparable enlargement of the focal adhesions in response to a MEK inhibitor. We conclude that focal adhesions that are formed in the 3D environment are similar in size and dynamics as those seen in the 2D setting.

Proteins implicated in the increase of adhesivity induced by suberoylanilide hydroxamic acid in leukemic cells.

We have previously shown that suberoylanilide hydroxamic acid (SAHA) treatment increases the adhesivity of leukemic cells to fibronectin at clinically relevant concentrations. Now, we present the results of the proteomic analysis of SAHA effects on leukemic cell lines using 2-DE and ProteomLab PF2D system. Histone acetylation at all studied acetylation sites reached the maximal level after 5 to 10 h of SAHA treatment. No difference in histone acetylation between subtoxic and toxic SAHA doses was observed. SAHA treatment induced cofilin phosphorylation at Ser3, an increase in vimentin and paxillin expression and a decrease in stathmin expression as confirmed by western-blotting and immunofluorescence microscopy. The interaction of cofilin with 14-3-3 epsilon was documented using both Duolink system and coimmunoprecipitation. However, this interaction was independent of cofilin Ser3 phosphorylation and the amount of 14-3-3-ε-bound cofilin did not rise following SAHA treatment. SAHA-induced increase in the cell adhesivity was associated with an increase in PAK phosphorylation in CML-T1 cells and was abrogated by simultaneous treatment with IPA-3, a PAK inhibitor. The effects of SAHA on JURL-MK1 cells were similar to those of other histone deacetylase inhibitors, tubastatin A and sodium butyrate. The proteome analysis also revealed several potential non-histone targets of histone deacetylases.

The molecular mechanisms of transition between mesenchymal and amoeboid invasiveness in tumor cells.

Tumor cells exhibit at least two distinct modes of migration when invading the 3D environment. A single tumor cell's invasive strategy follows either mesenchymal or amoeboid patterns. Certain cell types can use both modes of invasiveness and undergo transitions between them. This work outlines the signaling pathways involved in mesenchymal and amoeboid types of tumor cell motility and summarizes the molecular mechanisms that are involved in transitions between them. The focus is on the signaling of the Rho family of small GTPases that regulate the cytoskeleton-dependent processes taking place during the cell migration. The multiple interactions among the Rho family of proteins, their regulators and effectors are thought to be the key determinants of the particular type of invasiveness. Mesenchymal and amoeboid invasive strategies display different adhesive and proteolytical interactions with the surrounding matrix and the alterations influencing these interactions can also lead to the transitions.

Fibronectin-replating experiment: procedure and analysis.

In this review protocols are described for studying protein tyrosine kinase signalling upon integrin-mediated cell adhesion. We have outlined detailed procedures for fibronectin-replating experiment, biochemical examination of the phosphotyrosine content of cellular proteins by immunoblotting using phosphorylation-specific antibodies or immunoprecipitation and analysis with general phosphotyrosine antibodies. Despite great advances that were made toward optimizing the described procedures, all these methods still remain in many respects an art, given the plentiful of variables and the extent to which the optimum conditions vary from one experimental condition to the other. Examples of performed experiments using the described procedures thus also include notes regarding variability of approaches based on experimental conditions.

Molecular characterization of a calmodulin-like dictyostelium protein CalB.

A gene named calB was cloned and characterized in Dictyostelium. A relationship to calmodulin (CaM) is suggested by sequence identity (50%), similar exon-intron structure and cross-reactivity with anti-CaM sera. The level of calB mRNA is developmentally regulated with maxima during aggregation and in spores. CalB null cells grow normally, develop and produce viable spores. We demonstrated the capacity of tagged CalB to bind Ca(2+) using the (45)Ca(2+) overlay assay and showed that its mobility on SDS-PAGE is dependent on Ca(2+)/EGTA pretreatment.