Acquired resistance to BRAF inhibitors is mediated by BRAF splicing variants in BRAF V600E mutation-positive colorectal neuroendocrine carcinoma

The Targeted Degradation of BRAF V600E Reveals the Mechanisms of Resistance to BRAF-Targeted Treatments in Colorectal Cancer Cells

The BRAF V600E mutation is frequently found in cancer. It activates the MAPK pathway and promotes cancer cell proliferation, making BRAF an excellent target for anti-cancer therapy. While BRAF-targeted therapy is highly effective for melanoma, it is often ineffective against other cancers harboring the BRAF mutation. In this study, we evaluate the effectiveness of a proteolysis targeting chimera (PROTAC), SJF-0628, in directing the degradation of mutated BRAF across a diverse panel of cancer cells and determine how these cells respond to the degradation. SJF-0628 treatment results in the degradation of BRAF V600E and a decrease in Mek activation in all cell lines tested, but the effects of the treatment on cell signaling and cell proliferation are cell-line-specific. First, BRAF degradation killed DU-4475 and Colo-205 cells via apoptosis but only partially inhibited the proliferation of other cancer cell lines. Second, SJF-0628 treatment resulted in co-degradation of MEK in Colo-205 cells but did not have the same effect in other cell lines. Finally, cell lines partially inhibited by BRAF degradation also contain other oncogenic drivers, making them multi-driver cancer cells. These results demonstrate the utility of a PROTAC to direct BRAF degradation and reveal that multi-driver oncogenesis renders some colorectal cancer cells resistant to BRAF-targeted treatment.

SEM1 promotes tumor progression of glioblastoma via activating the akt signaling pathway

INTRODUCTION

SEM1, a 26 S proteasome complex subunit, is an essential regulator of tumor growth. However, the underlying mechanism of SEM1 mediated glioma progression remains to be elucidated.

METHODS

Data from bulk-tumor, single-cell, and spatial sequencing were analyzed to reveal correlations between SEM1 and clinical traits, cell types, and functional enrichment in gliomas. Immunohistochemistry was used to assess SEM1 expression. MTT, flow cytometry, apoptosis signature, epithelial-mesenchymal transition signature, Transwell, and organoid assays were used to study SEM1's effect on the malignant behavior of glioma (U251 and LN229) cells. Weighted gene co-expression network analysis (WGCNA) was conducted to construct an SEM1-mediated malignant regulatory network. Accordingly, survival analysis, therapeutic response, drug prediction, and molecular docking analyses were performed.

RESULTS

High SEM1 expression was observed in gliomas and correlated with worse clinical features and prognosis. Moreover, SEM1 is mainly localized in malignant cells (glioma cells). SEM1 knockout inhibited the proliferation, invasion, and migration of glioma cells and promoted their apoptosis. We also constructed an SEM1 malignant regulatory network that was bridged by the PI3K-Akt pathway. The network had a high prognostic value. Finally, drugs potentially targeting SEM1 were screened and docked to SEM1.

CONCLUSIONS

SEM1 is critically involved in the proliferation, apoptosis, invasion, and migration of glioma cells. The SEM1 malignant regulatory network shows high significance for the prognosis and treatment of gliomas.

Treatment of advanced non-small cell lung cancer with driver mutations: current applications and future directions

With the improved understanding of driver mutations in non-small cell lung cancer (NSCLC), expanding the targeted therapeutic options improved the survival and safety. However, responses to these agents are commonly temporary and incomplete. Moreover, even patients with the same oncogenic driver gene can respond diversely to the same agent. Furthermore, the therapeutic role of immune-checkpoint inhibitors (ICIs) in oncogene-driven NSCLC remains unclear. Therefore, this review aimed to classify the management of NSCLC with driver mutations based on the gene subtype, concomitant mutation, and dynamic alternation. Then, we provide an overview of the resistant mechanism of target therapy occurring in targeted alternations ("target-dependent resistance") and in the parallel and downstream pathways ("target-independent resistance"). Thirdly, we discuss the effectiveness of ICIs for NSCLC with driver mutations and the combined therapeutic approaches that might reverse the immunosuppressive tumor immune microenvironment. Finally, we listed the emerging treatment strategies for the new oncogenic alternations, and proposed the perspective of NSCLC with driver mutations. This review will guide clinicians to design tailored treatments for NSCLC with driver mutations.