GRP78 blockade overcomes acquired resistance to EGFR-tyrosine kinase inhibitors in non-small cell lung cancer.

AIMS: While significant upregulation of GRP78 has been documented in lung cancer patients, its association with resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) remains underexamined. Our study aimed to elucidate the functional importance of GRP78 in acquired resistance to EGFR-TKIs in non-small cell lung cancer (NSCLC) and to evaluate its potential as a therapeutic target. MAIN METHODS: Immunoblot analysis or flow cytometry was employed to assess several markers for endoplasmic reticulum (ER) stress and apoptosis. Ru(II) complex I and HA15, two known GRP78 inhibitors, were used to evaluate the functional role of GRP78. A Xenograft assay was performed to evaluate the in vivo anti-cancer effects of the GRP78 inhibitors. KEY FINDINGS: We validated a significant increase in GRP78 protein levels in HCC827-GR, H1993-GR, and H1993-ER cells. The EGFR-TKI-resistant cells overexpressing GRP78 exhibited significantly higher cell proliferation rates than did their parental counterparts. Notably, GRP78 inhibition resulted in a more profound anti-proliferative and apoptotic response via heightened ER stress and subsequent reactive oxygen species (ROS) production in EGFR-TKI-resistant cell lines compared with their parental cells. In xenograft models implanted with HCC827-GR, both Ru(II) complex I and HA15 significantly suppressed tumor growth and reduced tumor weight. Additionally, we confirmed that GRP78 plays a critical role in the proliferation of H1975, an EGFR-TKI-resistant T790M-mutant cell line, relative to other NSCLC cell lines. SIGNIFICANCE: Our findings strongly support targeting of GRP78 as a promising therapeutic strategy for NSCLC patients with acquired resistance to EGFR-TKIs.

Therapeutic strategy using novel RET/YES1 dual-target inhibitor in lung cancer.

Lung cancer represents a significant global health concern and stands as the leading cause of cancer-related mortality worldwide. The identification of specific genomic alterations such as EGFR and KRAS in lung cancer has paved the way for the development of targeted therapies. While targeted therapies for lung cancer exhibiting EGFR, MET and ALK mutations have been well-established, the options for RET mutations remain limited. Importantly, RET mutations have been found to be mutually exclusive from other genomic mutations and to be related with high incidences of brain metastasis. Given these facts, it is imperative to explore the development of RET-targeting therapies and to elucidate the mechanisms underlying metastasis in RET-expressing lung cancer cells. In this study, we investigated PLM-101, a novel dual-target inhibitor of RET/YES1, which exhibits notable anti-cancer activities against CCDC6-RET-positive cancer cells and anti-metastatic effects against YES1-positive cancer cells. Our findings shed light on the significance of the YES1-Cortactin-actin remodeling pathway in the metastasis of lung cancer cells, establishing YES1 as a promising target for suppression of metastasis. This paper unveils a novel inhibitor that effectively targets both RET and YES1, thereby demonstrating its potential to impede the growth and metastasis of RET rearrangement lung cancer.

Discovery of benzimidazole-indazole derivatives as potent FLT3-tyrosine kinase domain mutant kinase inhibitors for acute myeloid leukemia.

The FMS-like tyrosine kinase 3 (FLT3) gene encodes a class III receptor tyrosine kinase that is expressed in hematopoietic stem cells. The mutations of FLT3 gene found in 30% of acute myeloid leukemia (AML), leads to an abnormal constitutive activation of FLT3 kinase of the receptor and results in immature myeloblast cell proliferation. Although small molecule drugs targeting the FLT3 kinase have been approved, new FLT3 inhibitors are needed owing to the side effects and drug resistances arising from kinase domain mutations, such as D835Y and F691L. In this study, we have developed benzimidazole-indazole based novel inhibitors targeting mutant FLT3 kinases through the optimization of diverse chemical moieties substituted around the core skeleton. The most optimized compound 22f exhibited potent inhibitory activities against FLT3 and FLT3/D835Y, with IC50 values of 0.941 and 0.199 nM, respectively. Furthermore, 22f exhibited strong antiproliferative activity against an AML cell line, MV4-11 cells with a GI50 of 0.26 nM. More importantly, 22f showed single-digit nanomolar GI50 values in the mutant FLT kinase expressed Ba/F3 cell lines including FLT-D835Y (GI50 = 0.29 nM) and FLT3-F691L (GI50 = 2.87 nM). Molecular docking studies indicated that the compound exhibits a well-fitted binding mode as a type 1 inhibitor in the homology model of active conformation of FLT3 kinase.

TYRO3 blockade enhances anti-PD-1 therapy response by modulating expression of CCN1 in tumor microenvironment.

BACKGROUND: Immunological contexture differs across malignancies, and understanding it in the tumor microenvironment (TME) is essential for development of new anticancer agents in order to achieve synergistic effects with anti-programmed cell death protein-1 (PD-1) therapy. TYRO3, AXL, and MERTK receptors are bi-expressed in both cancer and immune cells, and thus emerge as promising targets for therapeutic intervention. Whereas AXL and MERTK have been extensively studied, the role of TYRO3, in the TME, is still undetermined. METHODS: Here, we screened the TYRO3-focused chemical library consisting of 208 compounds and presented a potent and highly selective TYRO3 inhibitor, KRCT87. We explored the role of TYRO3 using mouse engrafting MC38 or 4T1 tumors. We validated the results using flow cytometry, RNA sequencing analysis, gene knockdown or overexpression, ex vivo immune cells isolation from mouse models, immunoblotting and quantitative PCR. Flow cytometry was used for the quantification of cell populations and immunophenotyping of macrophages and T cells. Co-cultures of macrophages and T cells were performed to verify the role of CCN1 in the tumors. RESULTS: TYRO3 blockade boosts antitumor immune responses in both the tumor-draining lymph nodes and tumors in MC38-syngeneic mice models. Moreover, the combination of KRCT87 and anti-PD-1 therapy exerts significant synergistic antitumor effects in anti-PD-1-non-responsive 4T1-syngeneic model. Mechanistically, we demonstrated that inhibition of TYRO3-driven CCN1 secretion fosters macrophages into M1-skewing phenotypes, thereby triggering antitumor T-cell responses. CCN1 overexpression in MC38 tumors diminishes responsiveness to anti-PD-1 therapy. CONCLUSIONS: The activated TYRO3-CCN1 axis in cancer could dampen anti-PD-1 therapy responses. These findings highlight the potential of TYRO3 blockade to improve the clinical outcomes of anti-PD-1 therapy.

Mitoregulin controls mitochondrial function and stress-adaptation response during early phase of endoplasmic reticulum stress in breast cancer cells.

The proper regulation of mitochondrial function is important for cellular homeostasis. Especially, in cancer cells, dysregulation of mitochondria is associated with diverse cellular events such as metabolism, redox status, and stress responses. Mitoregulin (MTLN), a micro protein encoded by LINC00116, recently has been reported to control mitochondrial functions in skeletal muscle cells and adipocytes. However, the role of MTLN in cancer cells remains unclear. In the present study, we found that MTLN regulates membrane potential and reactive oxygen species (ROS) generation of mitochondria in breast cancer cells. Moreover, MTLN deficiency resulted in abnormal mitochondria-associated ER membranes (MAMs) formation, which is crucial for stress adaptation. Indeed, the MTLN-deficient breast cancer cells failed to successfully resolve ER (endoplasmic reticulum) stress, and cell vulnerability to ER-stress inducers was significantly enhanced by the downregulation of MTLN. In conclusion, MTLN controls stress-adaptation responses in breast cancer cells as a key regulator of mitochondria-ER harmonization, and thereby its expression level may serve as an indicator of the responsiveness of cancer cells to proteasome inhibitors.