D-1553: A novel KRASG12C inhibitor with potent and selective cellular and in vivo antitumor activity.

D-1553 is a small molecule inhibitor selectively targeting KRASG12C and currently in phase II clinical trials. Here, we report the preclinical data demonstrating antitumor activity of D-1553. Potency and specificity of D-1553 in inhibiting GDP-bound KRASG12C mutation were determined by thermal shift assay and KRASG12C -coupled nucleotide exchange assay. In vitro and in vivo antitumor activity of D-1553 alone or in combination with other therapies were evaluated in KRASG12C mutated cancer cells and xenograft models. D-1553 showed selective and potent activity against mutated GDP-bound KRASG12C protein. D-1553 selectively inhibited ERK phosphorylation in NCI-H358 cells harboring KRASG12C mutation. Compared to the KRAS WT and KRASG12D cell lines, D-1553 selectively inhibited cell viability in multiple KRASG12C cell lines, and the potency was slightly superior to sotorasib and adagrasib. In a panel of xenograft tumor models, D-1553, given orally, showed partial or complete tumor regression. The combination of D-1553 with chemotherapy, MEK inhibitor, or SHP2 inhibitor showed stronger potency on tumor growth inhibition or regression compared to D-1553 alone. These findings support the clinical evaluation of D-1553 as an efficacious drug candidate, both as a single agent or in combination, for patients with solid tumors harboring KRASG12C mutation.

Luminescent quantum dots: a very attractive and promising tool in biomedicine.

Luminescent semiconductor nanocrystals, also known as quantum dots (QDs), are generally composed of II-VI and III-V elements. Due to their quantum confinement of charge carriers in tiny spaces, QDs show some unique and fascinating optical properties, and are characterized as sharp and symmetrical emission spectra, high quantum yields, broad absorption spectra, good chemical and photo-stability and size dependent emission wavelength tunability. Recently, QDs have been successfully used as new fluorescent tags in many biological and biomedical fields, and will become a new promising tool in biomedical studies, clinical diagnostics, drug delivery and photodynamic therapy. In this review, firstly, the methodology of QDs preparation was introduced, which included organic synthesis, aqueous synthesis and microwave assisted aqueous synthesis. Secondly, some procedures for the QDs bio-conjugation with biomarkers were described. And then, some key applications of QDs were summarized, which mainly covered biomedical imaging, immunoassay, DNA hybridization, and photodynamic therapy. Finally, future prospects were discussed.

Characterization of quantum dot bioconjugates by capillary electrophoresis with laser-induced fluorescent detection.

In this paper, we present a universal, highly efficient and sensitive method for the characterization of quantum dot (QD) bioconjugates based on capillary electrophoresis with laser-induced fluorescent (LIF) detection. We first prepared CdTe QDs in aqueous phase by a chemical route with mercaptopropionic acid as a ligand, and then were coupled to certain proteins using bifunctional linkage reagent or electrostatic attraction. The QD bioconjugates were characterized by capillary electrophoresis with LIF detection. We found that QD bioconjugates were efficiently separated with free QDs by the optimization of buffer pH. Furthermore, we found that ultrafiltration was an effective and simple approach to purify QD conjugates with bovine serum albumin (BSA). Due to their broad absorption spectra and size dependent emission wavelength tunability, QDs can be excited to emit different colour fluorescence using a single wavelength laser source, and therefore, we believe that CE with LIF detection will become a universal and efficient tool for the characterization of QD bioconjugates.

[Proliferation inhibition of human lung adenocarcinoma cell line A549 transfected by RASSF1A gene].

OBJECTIVE: To determine the effects of exogenous RASSF1A gene on the proliferation and expression of P65 and subunit of NF-kappaB, in lung adenocarcinoma cell line A549. METHODS: pcDNA3.0-RASSF1A and pcDNA3. 0 were introduced into A549 cell line by lipofectin transfection, and the A549 cells stably expressing RASSF1A gene were established by G418 selection. The expression of RASSF1A was detected by Western blotting. The cytobiologic characterizations of the positive clone were analyzed by methythiazoletertraolium (MTT) assay and cytometry. The expressing of P65 was analyzed by RT-PCR and Western blotting. RESULTS: A549 cells stably expressing RASSF1A protein were established by lipofection mediated transfection and selected for further study. Compared with the nontransfected and vector transfected cells, the positive clone cells grew more slowly. Flow cytometric data showed that more positive clone cells went into phase G0/G1 and fewer cells went into phase S. The expression of P65 in nuclear protein in positive clone cells was lower than that of the control group while there was no obvious difference between the expression of p65 mRNA and P65 protein in total protein among the 3 groups. CONCLUSION: RASSF1A gene might suppress the proliferation of A549 cells through blocking the activity of P65 protein.

Highly luminescent CdTe quantum dots prepared in aqueous phase as an alternative fluorescent probe for cell imaging.

In this paper, our main aim is to explore the feasibility for application of luminescent CdTe quantum dots prepared in aqueous phase to live and fixed cell imaging. The highly luminescent CdTe quantum dots (QDs) were first prepared in aqueous phase using 3-mercaptopropionic acid (MPA) as a ligand, and then were covalently coupled to a plant lectin (UEA-1) and antibody anti-von Willebrand factors (anti-vWF) as fluorescent probes. Two probes QD-UEA-1 and QD-anti-vWF) were able to specifically bind the corresponding cell membrane receptor and cytoplasm immunogen, respectively. The good cell images were obtained in live cells and fixed cells using laser confocal scanning microscopy. Our preliminary results illustrated that CdTe QDs prepared in water phase were highly luminescent, water-soluble, stable, and easily conjugated with biomolecules since their surface were coated with MPA containing free carboxyl group. We predict that QDs prepared in water phase will probably become an attractive alternative probe in cellular imaging and bio-labeling.