Dysregulation of the PI3Kinase/AKT pathway is involved in the pathogenesis of many human malignancies. In acute leukemia, the AKT pathway is frequently activated, however mutations in the PI3K/AKT pathway are uncommon. In some cases, constitutive AKT activation can be linked to gain-of-function tyrosine kinase (TK) mutations upstream of the PI3K/AKT pathway. Inhibitors of the PI3K/AKT pathway are attractive candidates for cancer drug development, but so far clinical efficacy of PI3K inhibitors against various neoplasms has been moderate. Furthermore, specific MTORC1 inhibitors, acting downstream of AKT, have the disadvantage of activating AKT via feed-back mechanisms. We now evaluated the antitumor efficacy of NVP-BGT226, a novel dual pan-PI3K and MTORC1/2 inhibitor, in acute leukemia. Native leukemia blasts were stained to analyze for AKT phosphorylation levels on a flow cytometer. Efficacy of NVP-BGT226 in comparison to a second dual inhibitor, NVP-BEZ235, was determined with regard to cellular proliferation, autophagy, cell cycle regulation and induction of apoptosis in in vitro and ex vivo cellular assays as well as on the protein level. An isogenic AKT-autoactivated Ba/F3 model, different human leukemia cell lines as well as native leukemia patient blasts were studied. Isobologram analyses were set up to calculate for (super) additive or antagonistic effects of two agents. We show, that phosphorylation of AKT is frequently augmented in acute leukemia. NVP-BGT226 as well as NVP-BEZ235 profoundly and globally suppress AKT signaling pathways, which translates into potent antiproliferative effects. Furthermore, NVP-BGT226 has potent proapoptotic effects in vitro as well as in ex vivo native blasts. Surprisingly and in contrast, NVP-BEZ235 leads to a profound G1/G0 arrest preventing significant induction of apoptosis. Combination with TK inhibitors, which are currently been tested in the treatment of acute leukemia subtypes, overcomes cell cycle arrest and results in (super)additive proapoptotic effects for NVP-BGT226 – but also for NVP-BEZ235. Importantly, mononuclear donor cells show lower phospho-AKT expression levels and consequently, relative insensitivity towards dual PI3K-MTORC1/2 inhibition. Our data suggest a favorable antileukemic profile for NVP-BGT226 compared to NVP-BEZ235 – which provides a strong rationale for clinical evaluation of the dual PI3K-MTORC1/2 inhibitor NVP-BGT226 in acute leukemia.

It has been previously demonstrated in several cancer models, that Dronabinol (THC) may have anti-tumor activity – however, controversial data exists for acute leukemia. We have anecdotal evidence that THC may have contributed to disease control in a patient with acute undifferentiated leukemia. To test this hypothesis, we evaluated the antileukemic efficacy of THC in several leukemia cell lines and native leukemia blasts cultured ex vivo. Expression analysis for the CB1/2 receptors was performed by Western immunoblotting and flow cytometry. CB-receptor antagonists as well as a CRISPR double nickase knockdown approach were used to evaluate for receptor specificity of the observed proapoptotic effects. Meaningful antiproliferative as well as proapoptotic effects were demonstrated in a subset of cases – with a preference of leukemia cells from the lymphatic lineage or acute myeloid leukemia cells expressing lymphatic markers. Induction of apoptosis was mediated via CB1 as well as CB2, and expression of CB receptors was a prerequisite for therapy response in our models. Importantly, we demonstrate that antileukemic concentrations are achievable in vivo. Our study provides rigorous data to support clinical evaluation of THC as a low-toxic therapy option in a well defined subset of acute leukemia patients.

The micro- and nanostructures, chemical composition, and wettability of titanium surfaces are essential for dental implants’ osseointegration. Combining hydrophilicity and nanostructure has been shown to improve the cell response and to shorten the healing time. This study aimed to investigate the biological response to different wettability levels and nanotopographical modifications in aged and non-aged titanium surfaces. By plasma etching titanium surfaces with the fluorine gas 2,3,3,3-tetrafluoropropene (R1234yF), additional nanostructures were created on the sample surfaces. Furthermore, this treatment resulted in sustained superhydrophilicity and fluoride accumulation. We examined the effect of various nanostructuring processes and aging using scanning electron microscopy, roughness analyses, and wettability measurement. In addition, all the surface modifications were tested for their effects on fibroblast adhesion, proliferation, and viability as well as osteoblast differentiation. Our study indicates that the plasma etching, with 2,3,3,3-tetrafluoropropene, of the machined and SLA surface neither favored nor had an adverse effect on the biological response of the SAOS-2 osteoblast cell line. Although the fluorine-plasma-etched surfaces demonstrated improved fibroblast cell viability, they did not lead to improved early osseointegration. It is still unclear which surface properties mainly influence fibroblast and osteoblast adhesion. Further physiochemical aspects, such as electrostatic interaction and surface tension, are crucial to be analyzed along with wettability and roughness.

Various surface modification strategies are being developed to endow dental titanium implant surfaces with micro- and nano-structures to improve their biocompatibility, and first of all their osseointegration. These modifications have the potential to address clinical concerns by stimulating different biological processes. This study aims to evaluate the biological responses of ananatase-modified blasted/etched titanium (SLA-anatase) surfaces compared to blasted/acid etched (SLA) and machined titanium surfaces. Using unipolar pulsed direct current (DC) sputtering, a nanocrystalline anatase layer was fabricated. In vitro experiments have shown that SLA-anatase discs can effectively promote osteoblast adhesion and proliferation, which are regarded as important features of a successful dental implant with bone contact. Furthermore, anatase surface modification has been shown to partially enhance osteoblast mineralization in vitro, while not significantly affecting bacterial colonization. Consequently, the recently created anatase coating holds significant potential as a promising candidate for future advancements in dental implant surface modification for improving the initial stages of osseointegration.

Physicochemical modification of titanium implants aims to enhance early osseointegration by improving bioactivity. This study deposited and evaluated an anatase TiO₂ film on clinically relevant sandblasted, acid-etched titanium (Ti-SLA) to enhance in vitro bioactivity and osteogenic responses. An ~8 µm TiO₂-anatase coating was deposited on Ti-SLA by reactive pulsed DC magnetron sputtering. Surface characterization included FE-SEM, helium ion microscopy, and XRD. Wettability and surface free energy (SFE) were evaluated by contact angle analysis. In vitro bioactivity was assessed by hydroxyapatite (HA) formation in twofold-concentrated simulated body fluid (2× SBF). Osteoblast responses were evaluated through cell adhesion, viability, alkaline phosphatase activity, gene expression, and mineralization. The coating produced hierarchical multi-globular microstructures decorated with faceted anatase nanocrystals. Ti-SLA’s initial hydrophobicity converted to a superhydrophilic, high-energy surface with increased polar SFE. Homogeneous HA crystallites deposited exclusively on SLA-anatase in 2× SBF. SAOS-2 cells showed enhanced metabolic activity, ALP activity, osteogenic gene upregulation, and improved mineralized matrix, while primary human osteoblasts exhibited increased metabolic activity and calcium deposition. The anatase coating produced a superhydrophilic, high-energy micro-nano surface that accelerates HA formation and enhances osteoblast function in vitro, warranting in vivo validation for early osseointegration.