Lipid nanoparticles (LNPs) have proven themselves as transformative actors in chimeric antigen receptor (CAR) T cell therapy, surpassing traditional methods and addressing challenges like immunogenicity, reduced toxicity, and improved safety. Promising preclinical results signal a shift toward safer and more effective CAR T cell treatments. Ongoing research aims to validate these findings in clinical trials, marking a new era guided by LNPs utility in CAR therapy. Herein, we explore the preference for LNPs over traditional methods, highlighting the versatility of LNPs and their effective delivery of nucleic acids. Additionally, we address key challenges in clinical considerations, heralding a new era in CAR T cell therapy. Graphical Abstract

Resistance to endocrine therapy represents a major concern for patients with estrogen receptor α–positive (ERα+) breast cancer. Endocrine therapy resistance is commonly mediated by activated E2F signaling. A better understanding of the mechanisms governing E2F1 activity in resistant cells could reveal strategies for overcoming resistance. Here, we identified the long noncoding RNA (lncRNA) actin gamma 1 pseudogene 25 (AGPG) as a regulator of E2F1 activity in endocrine-resistant breast cancer. Expression of AGPG was increased in endocrine-resistant breast cancer cells, which was driven by epigenomic activation of an enhancer. AGPG was also abnormally upregulated in patient breast tumors, especially in the luminal B subtype, and high AGPG expression was associated with poor survival of patients with ERα+ breast cancer receiving endocrine therapy. The upregulation of AGPG mediated resistance to endocrine therapy and cyclin-dependent kinase 4/6 inhibition in breast cancer cells. Mechanistically, AGPG physically interacted with PURα, thus releasing E2F1 from PURα and leading to E2F1 signaling activation in ERα+ breast cancer cells. In patients with breast cancer, E2F1 target genes were positively and negatively correlated with expression of AGPG and PURα, respectively. Coadministration of chemically modified AGPG siRNA and tamoxifen strongly suppressed tumor growth in endocrine-resistant cell line–derived xenografts. Together, these results demonstrate that AGPG can drive endocrine therapy resistance and indicate that it is a promising biomarker and potential therapeutic target in breast cancer. Significance: Blockade of formation of the PURα/E2F1 complex by lncRNA AGPG activates E2F1 and promotes endocrine resistance, providing potential strategies for combatting endocrine-resistant breast cancer.

Proteolysis Targeting Chimera (PROTAC) is a heterobifunctional molecule comprising three core components: a target protein ligand (typically a small-molecule inhibitor), a linker, and an E3 ubiquitin ligase ligand. By harnessing the specificity of the endogenous ubiquitin-proteasome system (UPS), PROTACs induce ubiquitination and subsequent degradation of target proteins. This technology constitutes an advanced therapeutic strategy for selective protein degradation, thereby expanding the horizons of drug design. Its significant therapeutic potential extends to treating cancers, viral infections (e.g., HIV and SARS-CoV-2), and chronic diseases. Recent clinical studies on compounds such as ARV-471 have yielded encouraging results, validating the efficacy of this approach. Over the past decade, PROTAC technology has garnered widespread attention in biomedicine for its promise in developing novel targeted therapies. This review will elucidate the broad therapeutic prospects and future challenges of PROTACs by detailing their mechanism of action, recent advances, progress in targeted therapy research, and current clinical trial landscape.

The combination of CDK4/6 inhibitors (CDK4/6i) and endocrine therapy is the first-line therapy for ER+/Her2-breast cancer; however, the development of drug resistance limited the efficacy of the agents. Although activation of the IFN signaling pathway has been identified as a critical driver of intrinsic and acquired CDK4/6i resistance, it remains unknown how the IFN signaling pathway was activated in resistant cells. Here, we report that NSRP1, a regulator of alternative mRNA splicing is downregulated in CDK4/6i resistant breast cancer cells and contributes to CDK4/6i resistance by mediating alternative splicing of NSD2 mRNA and activation of the IFN signaling pathway. Knockdown of NSRP1 reduces CDK4/6i (palbociclib) sensitivity of MCF7 cells while overexpression of NSRP1 sensitizes MCF7-PalR cells towards palbociclib treatment. Mechanistically, RNA sequencing suggests that NSRP1 knockdown strongly activates the IFN signaling pathway in MCF7 cells and elevates the expression of most of the "IFN-related palbociclib-resistance Signature" (IRPS) genes. NSRP1 also regulates numerous alternative splicing (AS) events in breast cancer cells, several of which are key regulators of the IFN signaling pathway. Among them, the inclusion of NSD2 exon 2 is elevated upon NSRP1 knockdown. Our data further show that the inclusion of NSD2 exon 2 is increased in breast cancer and associated with the poor prognosis of patients. In addition, including NSD2 exon 2 elevates NSD2 protein expression to activate the IFN signaling pathway. This study unveils the critical role of NSRP1 in regulating the IFN signaling pathway and the CDK4/6i resistance, which could be a promising biomarker for predicting therapy response.

Alternative splicing generates cancer‐specific transcripts and is now recognized as a hallmark of cancer. However, the critical oncogenic spliceosome‐related proteins involved in triple‐negative breast cancer (TNBC) remain elusive. Here, we explored the expression pattern of spliceosome‐related proteins in TNBC, non‐TNBC, and normal breast tissues from The Cancer Genome Atlas breast cancer (TCGA‐BRCA) cohort, revealing higher expression of nearly half of spliceosome‐related proteins in TNBC than their counterparts. Among these TNBC‐specific spliceosome‐related proteins, the expression of SNRPB2 was associated with poor prognosis in patients with TNBC. In TNBC cells, the knockdown of SNRPB2 strongly suppressed cell proliferation and invasion and induced cell cycle arrest. Mechanistically, transcriptome data showed that SNRPB2 knockdown inactivated E2F1 signaling, which regulated the cell cycle. We further validated the downregulation of several cell cycle genes in SNRPB2 knockdown cells. Moreover, the analysis showed that SNRPB2 knockdown triggered the alteration of many alternative splicing events, most of which were skipping of exon. In TNBC cells, it was found that SNRPB2 knockdown led to the skipping of exon 6 in MDM4 pre‐mRNA, generating MDM4‐S transcript and downregulating MDM4 protein expression. More importantly, downregulation of MDM4 decreased retinoblastoma 1 (Rb1) protein expression, which is a target of MDM4 and a regulator of E2F1 signaling. In summary, the current study revealed an SNRPB2/MDM4/Rb axis in promoting the progression of TNBC, providing novel insights and novel targets for combating TNBC.