Branched-chain keto-acid dehydrogenase kinase regulates vascular permeability and angiogenesis to facilitate tumor metastasis in renal cell carcinoma.

Branched-chain keto-acid dehydrogenase kinase (BCKDK) is the rate-limiting enzyme of branched-chain amino acid (BCAA) metabolism. In the last six years, BCKDK has been used as a kinase to promote tumor proliferation and metastasis. Renal cell carcinoma (RCC) is a highly vascularized tumor. A high degree of vascularization promotes tumor metastasis. Our objective is to explore the relationship between BCKDK and RCC metastasis and its specific mechanism. In our study, BCKDK is highly expressed in renal clear cell carcinoma and promotes the migration of clear cell renal cell carcinoma (ccRCC). Exosomes from ccRCC cells can promote vascular permeability and angiogenesis, especially when BCKDK is overexpressed in ccRCC cells. BCKDK can also augment the miR-125a-5p expression in ccRCC cells and derived exosomes, thereby decreasing the downstream target protein VE-cadherin level, weakening adhesion junction expression, increasing vascular permeability, and promoting angiogenesis in HUVECs. The novel BCKDK/Exosome-miR-125a-5p/VE-cadherin axis regulates intercellular communication between ccRCC cells and HUVECs. BCKDK plays a critical role in renal cancer metastasis, may be used as a molecular marker of metastatic ccRCC, and even may become a potential target of clinical anti-vascular therapy for ccRCC.

Prognostic and Immunological Role of STK38 across Cancers: Friend or Foe?

Although STK38 (serine-threonine kinase 38) has been proven to play an important role in cancer initiation and progression based on a series of cell and animal experiments, no systemic assessment of STK38 across human cancers is available. We firstly performed a pan-cancer analysis of STK38 in this study. The expression level of STK38 was significantly different between tumor and normal tissues in 15 types of cancers. Meanwhile, a prognosis analysis showed that a distinct relationship existed between STK38 expression and the clinical prognosis of cancer patients. Furthermore, the expression of STK38 was related to the infiltration of immune cells, such as NK cells, memory CD4+ T cells, mast cells and cancer-associated fibroblasts in a few cancers. There were three immune-associated signaling pathways involved in KEGG analysis of STK38. In general, STK38 shows a significant prognostic value in different cancers and is closely associated with cancer immunity.

Discovery of a small-molecule NDR1 agonist for prostate cancer therapy.

Prostatic cancer (PCa) is a common malignant neoplasm in men worldwide. Most patients develop castration-resistant prostate cancer (CRPC) after treatment with androgen deprivation therapy (ADT), usually resulting in death. Therefore, investigating new therapeutic targets and drugs for PCa patients is urgently needed. Nuclear Dbf2-related kinase 1 (NDR1), also known as STK38, is a serine/threonine kinase in the NDR/LATS kinase family that plays a critical role in cellular processes, including immunity, inflammation, metastasis, and tumorigenesis. It was reported that NDR1 inhibited the metastasis of prostate cancer cells by suppressing epithelial-mesenchymal transition (EMT), and decreased NDR1 expression might lead to a poorer prognosis, suggesting the enormous potential of NDR1 in antitumorigenesis. In this study, we characterized a small-molecule agonist named aNDR1, which specifically bound to NDR1 and potently promoted NDR1 expression, enzymatic activity and phosphorylation. aNDR1 exhibited drug-like properties, such as favorable stability, plasma protein binding capacity, cell membrane permeability, and PCa cell-specific inhibition, while having no obvious effect on normal prostate cells. Meanwhile, aNDR1 exhibited good antitumor activity both in vitro and in vivo. aNDR1 inhibited proliferation and migration of PCa cells and promoted apoptosis of PCa cells in vitro. We further found that aNDR1 inhibited subcutaneous tumors and lung metastatic nodules in vivo, with no obvious toxicity to the body. In summary, our study presents a potential small-molecule lead compound that targets NDR1 for clinical therapy of PCa patients.

BCKDK regulates breast cancer cell adhesion and tumor metastasis by inhibiting TRIM21 ubiquitinate talin1.

Breast cancer is the most common malignant cancer in women worldwide. Cancer metastasis is the major cause of cancer-related deaths. BCKDK is associated with various diseases, including proliferation, migration, and invasion in multiple types of human cancers. However, the relevance of BCKDK to the development and progression of breast cancers and its function is unclear. This study found that BCKDK was overexpressed in breast cancer, associated with poor prognosis, and implicated in tumor metastasis. The downregulation of BCKDK expression inhibited the migration of human breast cancer cells in vitro and diminished lung metastasis in vivo. BCKDK perturbed the cadherin-catenin complex at the adherens junctions (AJs) and assembled focal adhesions (FAs) onto the extracellular matrix, thereby promoting the directed migration of breast cancer cells. We observed that BCKDK acted as a conserved regulator of the ubiquitination of cytoskeletal protein talin1 and the activation of the FAK/MAPK pathway. Further studies revealed that BCKDK inhibited the binding of talin1 to E3 ubiquitin ligase-TRIM21, leading to the decreased ubiquitination/degradation of talin1. In conclusion, identifying BCKDK as a biomarker for breast cancer metastasis facilitated further research on diagnostic biomarkers. Elucidating the mechanism by which BCKDK exerted its biological effect could provide a new theoretical basis for developing new markers for breast cancer metastasis and contribute to developing new therapies for the clinical treatment of breast cancer patients.

TOPK mediates immune evasion of renal cell carcinoma via upregulating the expression of PD-L1.

Although anti-PD-L1 therapy has been used in the clinical treatment of renal cell carcinoma (RCC), a proportion of patients are not sensitive to it, which may be attributed to the heterogeneity of PD-L1 expression. Here, we demonstrated that high TOPK (T-LAK cell-originated Protein Kinase) expression in RCC promoted PD-L1 expression by activating ERK2 and TGF-ß/Smad pathways. TOPK was positively correlated with PD-L1 expression levels in RCC. Meanwhile, TOPK significantly inhibited the infiltration and function of CD8+ T cells and promoted the immune escape of RCC. Moreover, inhibition of TOPK significantly enhanced CD8+ T cell infiltration, promoted CD8+ T cell activation, enhanced anti-PD-L1 therapeutic efficacy, and synergistically enhanced anti-RCC immune response. In conclusion, this study proposes a new PD-L1 regulatory mechanism that is expected to improve the effectiveness of immunotherapy for RCC.

The Crucial Role of AR-V7 in Enzalutamide-Resistance of Castration-Resistant Prostate Cancer.

Prostate cancer (PCa) has the second highest incidence of malignancies occurring in men worldwide. The first-line therapy of PCa is androgen deprivation therapy (ADT). Nonetheless, most patients progress to castration-resistant prostate cancer (CRPC) after being treated by ADT. As a second-generation androgen receptor (AR) antagonist, enzalutamide (ENZ) is the current mainstay of new endocrine therapies for CRPC in clinical use. However, almost all patients develop resistance during AR antagonist therapy due to various mechanisms. At present, ENZ resistance (ENZR) has become challenging in the clinical treatment of CRPC. AR splice variant 7 (AR-V7) refers to a ligand-independent and constitutively active variant of the AR and is considered a key driver of ENZR in CRPC. In this review, we summarize the mechanisms and biological behaviors of AR-V7 in ENZR of CRPC to contribute novel insights for CRPC therapy.

NEDD9 promotes invasion and migration of colorectal cancer cell line HCT116 via JNK/EMT.

Neural precursor cell-expressed, developmentally-downregulated 9 (NEDD9) is a multi-domain skeleton protein that serves an important role in the cell signaling process via modulating invasion, metastasis, proliferation and apoptosis of tumor cells. The present study identified that the expression levels of NEDD9 in colorectal cancer were elevated. Therefore, the effect of downregulating the expression of NEDD9 in terms of invasion and migration of colorectal cancer cells was investigated and the role of the JNK pathway in these processes was also investigated. The data revealed that downregulation of NEDD9 and JNK inhibitors suppressed invasion and migration, decreased expression levels of phosphorylated JNK, increased the expression levels of E-cadherin and decreased the expression levels of vimentin. In summary, NEDD9 promotes invasion and migration of colorectal cancer cells via the JNK pathway.