Breast cancer is the most commonly occurring cancer and second leading cause of mortality in women. Metformin is a widely prescribed anti-hyperglycemic drug, which is emerging as a potential cancer preventative and treatment agent. However, the mechanisms underlying the suppressive effects of metformin on cancer cell growth and the induction of cancer cell apoptosis are not fully elucidated. The present study aimed to identify the pathways regulated by metformin in two breast cancer cell lines, MDA‑MB‑231 and MDA‑MB‑435. Cells were treated with various concentrations of metformin and then evaluated with respect to viability, proliferation, adenosine triphosphate (ATP) and reactive oxygen species (ROS) levels, mitochondrial membrane potential (∆ψm), and the expression of anti‑ and pro‑apoptotic proteins. Metformin caused apoptosis in a concentration‑ and time‑dependent manner, and decreased cell viability and ATP production. Furthermore, metformin induced the generation of ROS and decreased the ∆ψm. Moreover, metformin downregulated the expression of the anti‑apoptotic proteins B‑cell lymphoma 2 (BCL‑2) and myeloid cell leukemia‑1, and upregulated the expression of the pro‑apoptotic BCL‑2‑associated X protein in MDA‑MB‑231 cells. These results demonstrate that the apoptotic and cytotoxic effects of metformin on breast cancer cells are mediated by the intrinsic mitochondria-mediated apoptosis pathway.

In non-small cell lung cancer (NSCLC), the heterogeneity promotes drug resistance, and the restricted expression of programmed death-ligand 1 (PD-L1) limits the immunotherapy benefits. Based on the mechanisms related to translation regulation and the association with PD-L1 of methyltransferase-like 3 (METTL3), the novel small-molecule inhibitor STM2457 is assumed to be useful for the treatment of NSCLC. We evaluated the efficacy of STM2457 in vivo and in vitro and confirmed the effects of its inhibition on disease progression. Next, we explored the effect of STM2457 on METTL3 and revealed its effects on the inhibition of catalytic activity and upregulation of METTL3 protein expression. Importantly, we described the genome-wide characteristics of multiple omics data acquired from RNA sequencing, ribosome profiling, and methylated RNA immunoprecipitation sequencing data under STM2457 treatment or METTL3 knockout. We also constructed a model for the regulation of the translation of METTL3 and PD-L1. Finally, we found PD-L1 upregulation by STM2457 in vivo and in vitro. In conclusion, STM2457 is a potential novel suppressor based on its inhibitory effect on tumor progression and may be able to overcome the heterogeneity based on its impact on the translatome. Furthermore, it can improve the immunotherapy outcomes based on PD-L1 upregulation in NSCLC.

Objective: Robust biomarker predicting efficacy of immunotherapy is limited. Circulating tumor DNA (ctDNA) sought to effectively monitor therapeutic response as well as disease progression. This study aims to investigate predictive role of ctDNA short-term dynamic change (6 weeks postimmunotherapy) in a single-arm, phase 2 trial of sintilimab plus docetaxel for previously treated advanced non-small cell lung cancer (NSCLC) patients. Methods: A total of 33 patients with advanced NSCLC with disease progression during or after any first-line treatment were prospectively enrolled between 2019 and 2020. Patients received sintilimab (200 mg, day 1, every 3 weeks) plus docetaxel (75 mg/m², day 3, every 3 weeks) for 4–6 cycles, followed by maintenance therapy with sintilimab (200 mg, day 1, every 3 weeks) until disease progression or unacceptable toxic effects. Blood samples were prospectively collected at baseline, and after 2 cycles of treatment (6 weeks post-treatment). All samples were subjected to targeted next-generation sequencing with a panel of 448 cancer-related genes. The landscape of high-frequency genomic profile of baseline and 6th week was described. Major molecular characteristics in preselected genes of interest associated with response to second-line chemoimmunotherapy were analyzed. The curative effects and prognosis of patients were evaluated. Results: Patients with ctDNA clearance at 6th week had decreased tumor volume, while most patients with positive ctDNA at 6th-week experienced an increase in tumor volume. Positive 6th-week ctDNA was associated with significantly shorter progression-free survival (PFS) (91 vs NR days; p<0.0001) and overall survival (47 vs 467 days; p =0.0039). Clearance of clonal mutations and none new clonal formation at 6th week were associated with longer PFS (mPFS 89 vs 266 days, p =0.003). ctDNA clearance at 6th week was an independent risk factor for progression or death (HR=100 (95% CI 4.10 to 2503.00), p=0.005). Conclusion: ctDNA status and ctDNA mutation clearance putatively serve as predictive biomarkers for sintilimab combined with docetaxel chemotherapy in pretreated advanced NSCLC patients.

Aberrant translation, a characteristic feature of cancer, is regulated by the complex and sophisticated RNA binding proteins (RBPs) in the canonical translation machinery. N6-methyladenosine (m⁶A) modifications are the most abundant internal modifications in mRNAs mediated by methyltransferase-like 3 (METTL3). METTL3 is commonly aberrantly expressed in different tumors and affects the mRNA translation of many oncogenes or dysregulated tumor suppressor genes in a variety of ways. In this review, we discuss the critical roles of METTL3 in translation regulation and how METTL3 and m⁶A reader proteins in collaboration with RBPs within the canonical translation machinery promote aberrant translation in tumorigenesis, providing an overview of recent efforts aiming to ‘translate’ these results to the clinic.

Heat shock protein B8 (HspB8) is a chaperone protein that is highly and constitutively expressed in the brain, cardiac tissue and many other organs. Recently, it has been shown that HspB8 can enhance cardiac function and render cardioprotection. However, the potential benefits of HspB8 action on ischemic stroke and the underlying mechanism(s) are largely unknown. To investigate whether HspB8 exerts protective effects on in vitro ischemia/ reperfusion (I/R) injury, mouse neuroblastoma cells were subjected to oxygen-glucose deprivation and reoxygenation (OGD/R). At first, we investigated and described the HspB8 expression and distribution in N2A cells exposed to OGD/R. Expressions of HspB8 were upregulated in mouse N2A cells after OGD/R, both at mRNA and protein levels. The level of HspB8 began increased after the OGD/R and peaked at 12 hour (12h) after the reperfusion, then declined at 24-hour time points, however, the level of HspB8 was still significantly increased compared to controls. Immunofluorescence analysis revealed that the expressed HspB8 was constitutively localized in the cytoplasm and at the periphery of the nucleus. Nuclear HspB8 levels increased after OGD/R compared with levels in the control, beginning as early as 4h reperfusion, the most conspicuous nuclear HspB8 staining was observed after 24h of reperfusion. Furthermore, overexpression of HspB8 reduced OGD/R -induced apoptosis by reducing the release of cytochrome c from mitochondria to cytosol. In conclusion, our data demonstrated that increased HspB8 expression and its nuclear shift in mouse N2A neuroblastoma cells protected against I/R injury, resulting in reduced apoptosis with the decrease of the release of cytochrome c from mitochondria to cytosol. Therefore, HspB8 might play a fundamental role in opposing and alleviating I/R injury in primary myocardial cells, and it may constitute a new therapeutic target for cerebral ischemic diseases.