TRPML1 triggers ferroptosis defense and is a potential therapeutic target in AKT-hyperactivated cancer.

Targeting ferroptosis for cancer therapy has slowed because of an incomplete understanding of ferroptosis mechanisms under specific pathological contexts such as tumorigenesis and cancer treatment. Here, we identify TRPML1-mediated lysosomal exocytosis as a potential anti-ferroptotic process through genome-wide CRISPR-Cas9 activation and kinase inhibitor library screening. AKT directly phosphorylated TRPML1 at Ser343 and inhibited K552 ubiquitination and proteasome degradation of TRPML1, thereby promoting TRPML1 binding to ARL8B to trigger lysosomal exocytosis. This boosted ferroptosis defense of AKT-hyperactivated cancer cells by reducing intracellular ferrous iron and enhancing membrane repair. Correlation analysis and functional analysis revealed that TRPML1-mediated ferroptosis resistance is a previously unrecognized feature of AKT-hyperactivated cancers and is necessary for AKT-driven tumorigenesis and cancer therapeutic resistance. TRPML1 inactivation or blockade of the interaction between TRPML1 and ARL8B inhibited AKT-driven tumorigenesis and cancer therapeutic resistance in vitro and in vivo by promoting ferroptosis. A synthetic peptide targeting TRPML1 inhibited AKT-driven tumorigenesis and enhanced the sensitivity of AKT-hyperactivated tumors to ferroptosis inducers, radiotherapy, and immunotherapy by boosting ferroptosis in vivo. Together, our findings identified TRPML1 as a therapeutic target in AKT-hyperactivated cancer.

Suppressive stroma-immune prognostic signature impedes immunotherapy in ovarian cancer and can be reversed by PDGFRB inhibitors.

BACKGROUND: As the most lethal gynecologic cancer, ovarian cancer (OV) holds the potential of being immunotherapy-responsive. However, only modest therapeutic effects have been achieved by immunotherapies such as immune checkpoint blockade. This study aims to propose a generalized stroma-immune prognostic signature (SIPS) to identify OV patients who may benefit from immunotherapy. METHODS: The 2097 OV patients included in the study were significant with high-grade serous ovarian cancer in the III/IV stage. The 470 immune-related signatures were collected and analyzed by the Cox regression and Lasso algorithm to generalize a credible SIPS. Correlations between the SIPS signature and tumor microenvironment were further analyzed. The critical immunosuppressive role of stroma indicated by the SIPS was further validated by targeting the major suppressive stroma component (CAFs, Cancer-associated fibroblasts) in vitro and in vivo. With four machine-learning methods predicting tumor immune subtypes, the stroma-immune signature was upgraded to a 23-gene signature. RESULTS: The SIPS effectively discriminated the high-risk individuals in the training and validating cohorts, where the high SIPS succeeded in predicting worse survival in several immunotherapy cohorts. The SIPS signature was positively correlated with stroma components, especially CAFs and immunosuppressive cells in the tumor microenvironment, indicating the critical suppressive stroma-immune network. The combination of CAFs' marker PDGFRB inhibitors and frontline PARP inhibitors substantially inhibited tumor growth and promoted the survival of OV-bearing mice. The stroma-immune signature was upgraded to a 23-gene signature to improve clinical utility. Several drug types that suppress stroma-immune signatures, such as EGFR inhibitors, could be candidates for potential immunotherapeutic combinations in ovarian cancer. CONCLUSIONS: The stroma-immune signature could efficiently predict the immunotherapeutic sensitivity of OV patients. Immunotherapy and auxiliary drugs targeting stroma could enhance immunotherapeutic efficacy in ovarian cancer.

Tubastatin A potently inhibits GPX4 activity to potentiate cancer radiotherapy through boosting ferroptosis.

Ferroptosis, an iron-dependent lipid peroxidation-driven programmed cell death, is closely related to cancer therapy. The development of druggable ferroptosis inducers and their rational application in cancer therapy are critical. Here, we identified Tubastatin A, an HDAC6 inhibitor as a novel druggable ferroptosis inducer through large-scale drug screening. Tubastatin A directly bonded to GPX4 and inhibited GPX4 enzymatic activity through biotin-linked Tubastatin A putdown and LC/MS analysis, which is independent of its inhibition of HDAC6. In addition, our results showed that radiotherapy not only activated Nrf2-mediated GPX4 transcription but also inhibited lysosome-mediated GPX4 degradation, subsequently inducing ferroptosis tolerance and radioresistance in cancer cells. Tubastatin A overcame ferroptosis resistance and radioresistance of cancer cells by inhibiting GPX4 enzymatic activity. More importantly, Tubastatin A has excellent bioavailability, as demonstrated by its ability to significantly promote radiotherapy-induced lipid peroxidation and tumour suppression in a mouse xenograft model. Our findings identify a novel druggable ferroptosis inducer, Tubastatin A, which enhances radiotherapy-mediated antitumor effects. This work provides a compelling rationale for the clinical evaluation of Tubastatin A, especially in combination with radiotherapy.

Multi-slice spiral CT findings of tubulovillous adenoma of the duodenum.

OBJECTIVES: To analyze the appearance of duodenal tubulovillous adenoma on multi-slice spiral CT images to facilitate early diagnosis and treatment to potentially improve prognosis. METHODS: We retrospectively analyzed clinical data and CT imaging findings of 11 cases of duodenal tubulovillous adenomas, all confirmed by pathology. The location, size, shape, CT density, relationship with surrounding structures, accompanying bile duct obstruction, and enhancement pattern of each lesion were documented. RESULTS: All 11 lesions occurred in the descending part of the duodenum. Ten cases occurred in the duodenal papilla area. Nine cases had a low-density ring sign or semicircle sign between the lesion and the adjacent normal intestinal wall on axial images. Eight cases had differing degrees of bile duct dilatation, five of which had concomitant pancreatic duct dilatation. Noncontrast images revealed uniform soft tissue density; contrast enhanced images showed moderate, mostly uniform enhancement, with the most enhancement in the venous phase. In the arterial phase, two lesions showed linear enhancing vessels. CONCLUSIONS: On multi-slice spiral CT imaging, duodenal tubulovillous adenomas have certain characteristics that could be used for clinical diagnosis and treatment. PRECIS: On multi-slice spiral CT imaging of duodenal tubulovillous adenoma, findings of nodular or cauliflower-like shape, uniform density, uniform moderate enhancement, and a peripheral low-density ring sign could improve diagnostic accuracy.

MiR-22 is frequently downregulated in medulloblastomas and inhibits cell proliferation via the novel target PAPST1.

Medulloblastoma is the most frequent malignant central nervous system tumor in children. MicroRNAs (miRs) are small, non-coding RNAs that target protein-coding and non-coding RNAs, and play roles in a variety of cellular processes through regulation of multiple targets. In the present study, we analyzed miR-22 expression and its effect in cell proliferation and apoptosis in medulloblastomas. Quantitative reverse transcription PCR (RT-PCR) revealed significantly lower expression of miR-22 in 19 out of 27 (70%) medulloblastomas, D341, DAOY, ONS-76 medulloblastoma cell lines, compared with normal cerebellum. Forced expression of miR-22 by lentiviral vector transfection reduced cell proliferation and induced apoptosis, while knockdown of miR-22 increased proliferative activity in DAOY and ONS-76 cells. DAOY cells with miR-22 overexpression in nude mice yielded tumors smaller than those originated from control DAOY cells. Microarray analysis in DAOY cells with forced miR-22 expression showed significant changes in expression profiles, PAPST1 being the most significantly (10 folds) downregulated gene. Quantitative RT-PCR revealed PAPST1 mRNA upregulation in 18 out of 27 (67%) medulloblastomas. In addition, a luciferase reporter assay in ONS-76 and DAOY cells suggested that miR-22 directly targets the PAPST1 gene, and lentivirus-mediated knockdown of PAPST1 suppressed proliferation of DAOY and ONS-76 medulloblastoma cells. These results suggest that frequently downregulated miR-22 expression is associated with cell proliferation in medulloblastomas, and this may be at least in part via PAPST1, which is a novel target of miR-22.