Mathematical Modelling Based on In Vivo Imaging Suggests CD137-Stimulated Cytotoxic T Lymphocytes Exert Superior Tumour Control Due to an Enhanced Antimitotic Effect on Tumour Cells

Several immunotherapeutic strategies for the treatment of cancer are under development. Two prominent strategies are adoptive cell transfer (ACT) of CTLs and modulation of CTL function with immune checkpoint inhibitors or with costimulatory antibodies. Despite some success with these approaches, there remains a lack of detailed and quantitative descriptions of the events following CTL transfer and the impact of immunomodulation. Here, we have applied ordinary differential equation models to two photon imaging data derived from a B16F10 murine melanoma. Models were parameterised with data from two different treatment conditions: either ACT-only, or ACT with intratumoural costimulation using a CD137 targeted antibody. Model dynamics and best fitting parameters were compared, in order to assess the mode of action of the CTLs and examine how the CD137 antibody influenced their activities. We found that the cytolytic activity of the transferred CTLs was minimal without CD137 costimulation, and that the CD137 targeted antibody did not enhance the per-capita killing ability of the transferred CTLs. Instead, the results of our modelling study suggest that an antiproliferative effect of CTLs exerted upon the tumour likely accounted for the majority of the reduction in tumour growth after CTL transfer. Moreover, we found that CD137 most likely improved tumour control via enhancement of this antiproliferative effect, as well as prolonging the period in which CTLs were inside the tumour, leading to a sustained duration of their antitumour effects following CD137 stimulation.

New Series of Double-Modified Colchicine Derivatives: Synthesis, Cytotoxic Effect and Molecular Docking

Colchicine is a well-known anticancer compound showing antimitotic effect on cells. Its high cytotoxic activity against different cancer cell lines has been demonstrated many times. In this paper we report the syntheses and spectroscopic analyses of novel colchicine derivatives obtained by structural modifications at C7 (carbon-nitrogen single bond) and C10 (methylamino group) positions. All the obtained compounds have been tested in vitro to determine their cytotoxicity toward A549, MCF-7, LoVo, LoVo/DX, and BALB/3T3 cell lines. The majority of obtained derivatives exhibited higher cytotoxicity than colchicine, doxorubicin and cisplatin against the tested cancerous cell lines. Additionally, most of the presented derivatives were able to overcome the resistance of LoVo/DX cells. Additionally, their mode of binding to β-tubulin was evaluated in silico. Molecular docking studies showed that apart from the initial amides 1 and 2, compound 14, which had the best antiproliferative activity (IC50 = 0.1–1.6 nM), stood out also in terms of its predicted binding energy and probably binds best into the active site of βI-tubulin isotype.

SAT-312 Beta-Arrestin 2 Is Required for Dopamine Receptor Type 2 Inhibitory Effects on Akt Phosphorylation and Cell Proliferation in Pituitary Tumors

Dopamine receptor type 2 (DRD2) agonists are the first-choice treatment for PRL-secreting pituitary tumors but are poorly effective in non-functioning pituitary neuroendocrine tumors (NF-PitNETs). DRD2 reduces AKT phosphorylation in lactotrophs, but no data are available in NF-PitNETs. DRD2 effects on AKT are mediated by a β-arrestin 2-dependent mechanism in mouse striatum. The aim of this study was to investigate DRD2 effects on AKT phosphorylation and cell proliferation in human primary cultured NF-PitNET cells and in rat tumoral lactotroph cells MMQ, and to test β-arrestin 2 involvement. We found that DRD2 agonist BIM53097 induced a reduction of p- AKT /total-AKT ratio in MMQ (-32.8±17.6%, p<0.001 vs basal) and in a subset (n=15/41,36.6%) of NF-PitNETs (subgroup 1). In the remaining NF-PitNETs (subgroup 2), BIM53097 induced an increase of p- AKT. The ability of BIM53097 to reduce p-AKT correlated to its antimitotic effect, since the majority of subgroup 1 NF-PitNETs was responsive to BIM53097 and nearly all subgroup 2 NF-PitNETs were resistant. β-arrestin2 was expressed in MMQ and in 80% of subgroup 1 NF-PitNETs, whereas it was undetectable in 77% of subgroup 2 NF-PitNETs. In MMQ, β-arrestin 2 silencing prevented DRD2 inhibitory effects on p-AKT and cell proliferation. Accordingly, β-arrestin 2 transfection in subgroup 2 NF-PitNETs conferred to BIM53097 the ability to inhibit both p-AKT and cell growth. In conclusion, we demonstrated that β-arrestin 2 is required for DRD2 inhibitory effects on AKT phosphorylation and cell proliferation in MMQ and NF-PitNETs, paving the way for a potential role of β-arrestin 2 as a biomarker predicting NF-PitNETs responsiveness to treatment with dopamine agonists.

OBTENCIÓN DE UNA FRACCIÓN ANTIMITÓTICA DEL EXTRACTO ETANÓLICO DE LA MACROALGA DIGENIA SIMPLEX

Marine algae have been widely studied by natural products chemists in the search of antitumor agents and the development of new therapeutic agents against cancer. Extracts of the red alga Digenia simplex display a powerful antimitotic effect in cancer cell lines. Therefore, it is of extreme importance to determine what substances are responsible of this activity. In order to achieve this objective, the ethanol extract of Digenia simplex was subject to chromatographic fractionation guided by evaluation of antimitotic activity on the Jurkat cell line (human myeloid lymphoma). Additionally, the most active fraction obtained was tested for cytotoxicity. Normal phase column chromatography and preparatory thin layer chromatography were used for extract fractionation. Cytotoxicity was assessed by cellular viability methods, determining cellular viability by the exclusion of the vital dye trypan blue. A cytotoxic and antimitotic fraction of polar nature was obtained. This fraction behaved in a similar way to the antineoplasic drug Colcemid.

Interactions of laulimalide, peloruside, and their derivatives with the isoforms of β-tubulin

The investigational anticancer agents laulimalide and peloruside are known to exert an antimitotic effect on cells by binding to β-tubulin. The binding affinities of derivatives of laulimalide and peloruside to all known isoforms of human β-tubulin were calculated using molecular mechanical, molecular dynamical, and quantum mechanical methods. Several of the derivatives are predicted to have improved β-tubulin binding affinities compared to the parent structures. These results can form the starting point for developing laulimalide or peloruside derivatives with greater specificity for the particular β-tubulin isoforms, which are overexpressed in certain tumours.