Mediation of Ferroptosis Suppressor Protein 1 Expression via 4-Hydroxy-2-Nonenal Accumulation Contributes to Acquisition of Resistance to Apoptosis and Ferroptosis in Diffuse Large B-Cell Lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma. New therapeutic strategies are needed for the treatment of refractory DLBCL. 4-Hydroxy-2-nonenal (4-HNE) is a cytotoxic lipid peroxidation marker, which alters intracellular signaling and induces genetic mutations. Lipid peroxidation is associated with nonapoptotic cell death, called ferroptosis. However, the relationship between 4-HNE accumulation and feroptotic regulators in DLBCL has not been fully evaluated. Here, we aimed to evaluate the accumulation of lipid peroxide and the expression of ferroptosis suppressor protein 1 (FSP1) in DLBCL using immunohistochemistry. We found a significant increase in the expression of FSP1 in cases with nuclear 4-HNE accumulation (P = .021). Both nuclear and cytoplasmic 4-HNE accumulation and FSP1 positivity were independent predictors of worse prognosis. In vitro exposure to 4-HNE resulted in its concentration- and time-dependent intracellular accumulation and increased expression of FSP1. Furthermore, short-term (0.25 and 1.0 µM) or long-term (0.25 µM) exposure to 4-HNE induced resistance to not only apoptosis but also ferroptosis. Taken together, regulation of FSP1 through 4-HNE accumulation may attenuate resistance to cell death in treatment-resistant DLBCL and might help develop novel therapeutic strategies for refractory DLBCL.

Gene expression profiling of pancreatic neuroendocrine carcinoma and mixed neuroendocrine-non-neuroendocrine neoplasm.

Pancreatic neuroendocrine carcinoma (NEC) and mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) are rare pancreatic malignant tumors, and comprehensive gene analyses are scarce. In this study, six NECs and six MiNENs were collected, immunohistochemistry for synaptophysin, chromogranin A, INSM1, Ki-67, and Rb was conducted, and KRAS mutational status was examined. Among these cases, comprehensive gene expression analysis of oncogene pathways using nCounter® were performed with six NECs and four MiNENs, and those data were compared with that of three pancreatic ductal adenocarcinomas (PDACs), with that of three normal pancreatic ducts, and with each other. By dividing NEC and MiNEN cases into KRAS-mutated group and KRAS-wild group, the difference of clinicopathological data and gene expression profiling data were examined between the two groups. Compared to the data of normal pancreatic epithelium, all 13 cancer-related pathways were upregulated in PDAC, MiNEN, and NEC group with more upregulation in this order. Compared to the data of PDAC, genes of DNA Damage repair pathway was most upregulated both in NECs and MiNENs. Regarding the difference between KRAS-mutated and KRAS-wild groups, several genes were differentially expressed between the two, where MMP7 was the upregulated gene with highest p-value and NKD1 was the downregulated gene with highest p-value in KRAS-mutated group. From the extent of upregulation of 13 pathways, MiNEN was considered more progressed stage than PDAC, and NEC was considered more progressed than MiNEN. From the comparison of KRAS-mutated and KRAS-wild NECs and MiNENs, several differentially expressed genes were identified in this study.

Regulation of 4-HNE via SMARCA4 Is Associated with Worse Clinical Outcomes in Hepatocellular Carcinoma.

Accumulation of 4-hydroxynonenal (4-HNE), a marker of lipid peroxidation, has various favorable and unfavorable effects on cancer cells; however, the clinicopathological significance of its accumulation in hepatocellular carcinoma (HCC) and its metabolic pathway remain unknown. This study analyzed 4-HNE accumulation and its clinicopathological significance in HCC. Of the 221 cases, 160 showed relatively low accumulation of 4-HNE in HCC tissues, which was an independent prognostic predictor. No correlation was found between 4-HNE accumulation and the expression of the antioxidant enzymes glutathione peroxidase 4, ferroptosis suppressor protein 1, and guanosine triphosphate cyclohydrolase 1. Therefore, we hypothesized that 4-HNE metabolism is up-regulated in HCC. A database search was focused on the transcriptional regulation of aldo-keto reductases, alcohol dehydrogenases, and glutathione-S-transferases, which are the metabolic enzymes of 4-HNE, and seven candidate transcription factor genes were selected. Among the candidate genes, the knockdown of SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a, member 4 (SMARCA4) increased 4-HNE accumulation. Immunohistochemical analysis revealed an inverse correlation between 4-HNE accumulation and SMARCA4 expression. These results suggest that SMARCA4 regulates 4-HNE metabolism in HCC. Therefore, targeting SMARCA4 provides a basis for a new therapeutic strategy for HCC via 4-HNE accumulation and increased cytotoxicity.

Stratification of lung squamous cell carcinoma based on ferroptosis regulators: Potential for new therapeutic strategies involving ferroptosis induction.

OBJECTIVES: Lung squamous cell carcinoma (LSCC) exhibits poor response to treatment compared with other lung cancer subtypes, resulting in worse prognosis. Therefore, new therapeutic strategies are required for advanced LSCC. Ferroptosis is a recently discovered nonapoptotic cell death caused by intracellular lipid peroxidation that can bring about effective cell death in cancer cells resistant to apoptosis. Hence, ferroptosis is a potential therapeutic strategy for refractory cancer. MATERIALS AND METHODS: In this study, we performed clinicopathological and molecular analyses on tumor specimens from 270 patients with squamous cell lung cancer, focusing on the expression of glutathione peroxidase 4 (GPX4) and ferroptosis suppressor protein 1 (FSP1), which are known to be key regulators of ferroptosis, and the accumulation of 4-hydroxynoneral (4-HNE), a lipid peroxidation marker. RESULTS: Immunohistochemistry revealed that patients with low 4-HNE accumulation and low levels of GPX4 or FSP1 had significantly worse prognoses than other patients (P = 0.001). This stratification was an independent prognostic predictor (P = 0.003). A dramatic cell death synergistic effect was observed on LSCC-derived LK-2 and EBC1 cells treated with GPX4 and FSP1 inhibitors. This effect was completely inhibited by treatment with the ferroptosis inhibitor. Notably, this was not the case in LK-2 cells treated with the apoptosis inhibitor, and in these cells, ferroptosis was induced. CONCLUSION: Ferroptosis regulators GPX4 and FSP1 are associated with lung squamous cell cancer cancer's prognosis. We present the clinicopathological and molecular basis of novel therapeutic strategies for refractory LSCC.

HADHB, a fatty acid beta-oxidation enzyme, is a potential prognostic predictor in malignant lymphoma.

In haematological malignancies, such as malignant lymphoma, reprogramming of fatty acid metabolism favours tumour cell survival and drug resistance. Hydroxyacyl-CoA dehydrogenase trifunctional multienzyme complex subunit alpha (HADHA), an enzyme involved in fatty acid beta-oxidation (FAO), is overexpressed in high-grade lymphoma and is a predictor of poor prognosis in diffuse large B-cell lymphoma (DLBCL). HADHB forms a heterodimer with HADHA and functions as an FAO enzyme together with HADHA; however, the relevance of its expression in malignant lymphoma is unknown. In this study, we investigated the roles and antitumour effects of HADHB expression in malignant lymphoma. Immunohistochemical analysis showed that HADHB was frequently overexpressed in the high-grade lymphoma subtype. HADHB overexpression was observed in 68% (87/128) of DLBCL cases and was an independent predictor of poor prognosis (p=0.001). In vitro analysis demonstrated that HADHB knockdown suppressed cell proliferation in LCL-K and MD901 cells (p<0.05). Additionally, treatment with the FAO inhibitor, ranolazine, increased cell death in control cells compared with that in HADHB knockdown LCL-K and MD901 cells (p<0.01). Cell death was also suppressed by the ferroptosis inhibitor, ferrosatin-1, in LCL-K and MD901 cells (p<0.05). Collectively, these findings provide basic evidence for the development of new cell death-based therapies for refractory malignant lymphoma. We plan to perform prospective studies and preclinical studies using animal models to confirm these results.