XS-2, a novel potent dual PI3K/mTOR inhibitor, exhibits high in vitro and in vivo anti-breast cancer activity and low toxicity with the potential to inhibit the invasion and migration of triple-negative breast cancer.

Breast cancer has become the most commonly diagnosed cancer, surpassing lung cancer, with 2.26 million new breast cancers worldwide in 2020. Hence, there is an urgent need to develop effective molecularly targeted therapeutic drugs to treat breast cancer. In this paper, we designed, synthesized and screened a novel thiophene-triazine derivative, XS-2, as a potent dual PI3K/mTOR inhibitor for the treatment of breast cancer. Also, XS-2 was found to be potentially effective against triple-negative breast cancer (TNBC) in vitro during the investigation. We evaluated the in vitro inhibitory effect of XS-2 on 10 cancer cell lines by MTT and 6 kinases to investigated its in vivo antitumor activity in MCF-7 xenograft tumor-bearing BALB/c nude mice. In addition, the in vitro/in vivo toxicity to mice was also assessed by hemolytic toxicity, H&E staining and blood biochemical analysis. In order to investigate the antitumor mechanism of XS-2, a series of experiments were carried out in vitro/in vivo animal model and molecular biological levels such as the cell cycle and the apoptosis assay, real-time PCR, western blot, docking and molecular simulations analysis, etc. What's more, wound healing assay, Transwell and Western Blot were applied to explore the ability of XS-2 to inhibit the cell invasion and migration. The results showed that XS-2 exhibited strong antitumor activity both in vitro and in vivo. The inhibitory activities of XS-2 on ten cancer cell lines were ranging from 1.07 ± 0.11 to 0.002 ± 0.001 µM, which were 1565 times better than that of the lead compound GDC-0941, inhibitory activities against PI3Kα and mTOR kinases were 291.0 and 60.8 nM, respectively. Notably, XS-2 not only showed significant in vivo antitumor activity and low toxicity, with the tumor inhibition rate of 57.0 %, but also exhibited strong inhibitory in the expression of related proteins of PI3K pathway in tumor tissues. In addition, XS-2 significantly inhibited breast cancer MCF-7 and MDA-MB-231 cells in a concentration- and time-dependent manner, and inhibited the migration and invasion ability of MDA-MB-231 and MCF-7 cells. More than that, XS-2 could inhibit the increase of the expression levels of N-cadherin and vimentin upregulated by EGF and reversed the E-cadherin expression down regulated by EGF, resulting in inhibiting EMT in MCF-7 and MDA-MB-231 cells. The results showed that XS-2 was expected to be successfully developed as a high-efficiency and low-toxicity breast cancer therapeutic drug with the potential to inhibit the invasion and migration of TNBC. This provides a new research idea for the treatment of TNBC, which is of great significance.

Recent advances of molecular mechanisms of regulating PD-L1 expression in melanoma.

Melanoma is a highly invasive malignant tumor, metastasis can occur in the early stage of the tumor, and the prognosis of patients in the late stage is extremely poor. Programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) immune checkpoint inhibitors have made a major breakthrough in cancer treatment, which makes the treatment of melanoma enter a new period. The expression of PD-L1 in melanoma is an important biomarker to predict the inhibitory response to the immune checkpoint and is considered to be an independent prognostic indicator of melanoma. Although the related immune checkpoint inhibitors have achieved some good results, the regulation of PD-L1 expression in melanoma is complex and contains multiple types, and few detailed summaries have been done on all types of regulation, so it is very important to explore the complicated regulation mechanism of PD-L1 in melanoma. In this review, we systematically summarize the latest progress on the mechanism of PD-L1 expression regulation in melanoma. The regulatory factors positively related to PD-L1 include internal factors, external induction, signal pathway, transcription factors, epigenetics (Hypomethylation, HDAC6), translation and post-translation levels, while factors negatively related to PD-L1 include microRNA and epigenetics (HDAC8). In addition, the regulation of PD-L1 on the exosome surface is mediated by IFN-γ and there is a positive correlation between them. We hope this review will lay a foundation for the development of more effective and less toxic drugs for immunotherapy of melanoma.

2-Methoxy-5((3,4,5-trimethosyphenyl)seleninyl) phenol (SQ) inhibits cancer cell metastasis behavior of TNBC via suppressing EMT and VEGF.

Triple-negative breast cancer (TNBC) is highly metastatic and lacks effective therapeutic targets among several subtypes of breast cancer. Cancer metastasis promotes the malignancy of TNBC and is closely related to the poor prognosis of the TNBC patients. We aim to explore novel agents that effectively inhibit cancer metastasis to treat TNBC. In our study, 2-Methoxy-5((3,4,5-trimethosyphenyl)seleninyl) phenol (SQ), a CA-4 analogue, could inhibit cell motility and invasion in MDA-MB-231 cells, and the mechanism is closely associated to the inhibition of epithelial-to-mesenchymal transition (EMT). Meanwhile, SQ significantly inhibited the expression and secretion of vascular endothelial growth factor (VEGF) in MDA-MB-231 cells. Moreover, the conditioned medium from SQ-treated MDA-MB-231 cells significantly inhibited the motility and invasion of human umbilical vein endothelial cells (HUVECs), which was correlated with the inhibition of EMT process in HUVECs. In addition, exogenous application of VEGF reversed the occurrence of EMT in HUVECs which stimulated by conditioned medium from SQ-treated cells. Furthermore, SQ inhibited vasculogenic mimicry (VM) formation in MDA-MB-231 cells, which was associated with VE-cadherin and EphA2 down-regulation. This study indicates that SQ inhibits MDA-MB-231 cell metastasis through suppressing EMT and VEGF, thereby implicating this compound might be a potential therapeutic agent against metastatic TNBC.

Design, synthesis, and docking studies of quinazoline analogues bearing aryl semicarbazone scaffolds as potent EGFR inhibitors.

Two series of quinazoline derivatives bearing aryl semicarbazone scaffolds (9a-o and 10a-o) were designed, synthesized and evaluated for the IC50 values against four cancer cell lines (A549, HepG2, MCF-7 and PC-3). The selected compound 9o was further evaluated for the inhibitory activity against EGFR kinases. Four of the compounds showed excellent cytotoxicity activity and selectivity with the IC50 values in single-digit µM to nanomole range. Two of them are equal to more active than positive control afatinib against one or more cell lines. The most promising compound 9o showed the best activity against A549, HepG2, MCF-7 and PC-3 cancer cell lines and EGFR kinase, with the IC50 values of 1.32±0.38µM, 0.07±0.01µM, 0.91±0.29µM and 4.89±0.69µM, which were equal to more active than afatinib (1.40±0.83µM, 1.33±1.28µM, 2.63±1.06µM and 3.96±0.59µM), respectively. Activity of the most promising compound 9o (IC50 56nM) against EGFR kinase was slightly lower to the positive compound afatinib (IC50 1.6nM) but more active than reference staurosporine (IC50 238nM). The result of flow cytometry, with the dose of compound 9o increasing, which indicated the compound 9o could induce remarkable apoptosis of A549 and cells in a dose dependent manner. Structure-activity relationships (SARs) and docking studies indicated that replacement of the cinnamamide group by aryl semicarbazone scaffolds slightly decreased the anti-tumor activity. The results suggested that hydroxy substitution at C-4 had a significant impact on the activity and replacement of the tetrahydrofuran group by methyl moiety was not beneficial for the activity.