Molecular Cancer Research最新文献

TRAP1, the mitochondrial isoform of HSP90, has emerged as a key regulator of cancer cell metabolism, yet the mechanisms by which it rewires nutrient utilization remain poorly understood. We previously reported that TRAP1 loss increases glutamine (Gln) dependency of mitochondrial respiration following glucose (Glc) withdrawal. In this study, we investigate how TRAP1 deletion impacts Glc metabolism and the mechanisms enabling Gln retention to support mitochondrial respiration via reductive carboxylation and the oxidative TCA cycle. TRAP1 knockout (KO) in bladder and prostate cancer cells recapitulates the carbon source-specific metabolic rewiring previously observed. Stable isotope tracing reveals that although Glc oxidation remains functional, TRAP1 KO reduces overall Glc uptake and its contribution to glycolysis and the pentose phosphate pathway. This effect is consistent across multiple cell lines. Concurrently, TRAP1-deficient cells exhibit increased Gln retention and reliance, potentially due to downregulation of the cystine/glutamate antiporter SLC7A11/xCT. Supporting this, xCT overexpression reduces Gln-dependent respiration in TRAP1 KO cells. qPCR and proteasome inhibition assays suggest that xCT is regulated posttranslationally via protein stability. Notably, xCT suppression does not trigger ferroptosis, indicating a selective adaptation rather than induction of cell death. Together, our findings suggest that TRAP1 loss decreases Glc uptake while preserving its metabolic fate, promoting Gln conservation through xCT downregulation to maintain mitochondrial respiration without inducing ferroptosis.

Implications: These results reveal a TRAP1-dependent mechanism of metabolic rewiring in cancer cells and identify xCT-mediated Gln conservation as a key adaptive response, underscoring TRAP1 as a potential metabolic vulnerability and therapeutic target in tumors with altered nutrient utilization.

Cutaneous T-cell lymphoma (CTCL) is a multistage disease characterized by rapid dissemination of malignant T lymphocytes from skin lesions to visceral organs and bone marrow. The cytokine IL-9 and its receptor (IL-9R) are aberrantly overexpressed in CTCL lesions and function to enhance tumor cell survival. In this study, we uncovered a critical new role for IL-9 as a potent inducer of migration of malignant T cells. Stimulation of IL-9R-expressing T-cell lymphoma cells with IL-9 induced a pseudohypoxic cellular state by elevating downstream levels of the promigratory and oxygen-sensing transcription factor hypoxia-inducible factor (HIF)-1α. High-throughput quantitative proteomic analyses of pseudohypoxic malignant T cells identified the actin-modulating protein cofilin-1 (CFL-1) as a promigratory CTCL-intrinsic target downstream of IL-9-HIF-1α signaling. Consistently, multicolor immunofluorescence staining revealed marked coexpression of CFL-1 with HIF-1α in both IL-9-treated human lymphoma cell lines and in patient CTCL skin biopsies compared with normal controls. Genetic knockdown of IL9R or HIF1A in human T-cell lymphoma lines by RNAi significantly reduced both HIF-1α and CFL-1 coexpression and reversed IL-9-induced migration. Finally, pharmacologic antagonism of HIF-1α activity using the FDA-designated orphan drug echinomycin significantly abrogated IL-9-triggered migration of both malignant T-cell lines and patient-derived T-cell lymphoma cells from CTCL biospecimens.

Implications: Our results uncover a CTCL-intrinsic IL-9-HIF-1α-CFL-1 axis as a critical promoter of malignant T-cell migration. They further identify HIF-1α and CFL-1 as promising therapeutic targets to mitigate IL-9-induced CTCL dissemination.

Bone metastasis continues to be the greatest challenge in treating patients with prostate cancer despite ongoing research. In bone, prostate cancer tumors hijack normal bone remodeling processes to drive cancer progression. However, it is unclear how these interactions drive bone-metastatic prostate cancer growth in the bone environment. To understand the mechanisms associated with bone-metastatic prostate cancer regulation of mesenchymal stem cells (MSC), we previously identified that bone-metastatic prostate cancer induces MSC expression of the pro-inflammatory chemokine CXCL8 and its mouse functional homologue Cxcl1. To date, there has been little to no information about the role of CXCL1/8 in MSC biology and its impact in the tumor-bone environment. Using genetic deletion of Cxcl1, we discovered a novel role for Cxcl1/8 in regulating MSC osteoblast differentiation, such that targeted deletion of Cxcl1 enhanced MSC osteoblastogenesis. Despite the osteogenic nature of prostate cancer, co-injection of Cxcl1 knockout (KO) MSCs with bone-metastatic prostate cancer in bone significantly suppressed tumor growth compared with co-injection with scrambled control (non-targeting) MSCs, even in the presence of three times more prostate cancer to MSCs. Furthermore, bulk RNA sequencing revealed immune response pathways, both in Cxcl1-KO MSCs and bone-metastatic prostate cancer tumors containing Cxcl1-KO MSCs. In support of this, Cxcl1-KO MSCs reduced immature neutrophils in the bone environment, while increasing monocytes. These findings demonstrate the importance of MSC-derived Cxcl1 in the bone microenvironment and highlight the importance of Cxcl1 in bone-metastatic prostate cancer progression.

Implications: MSC-derived Cxcl1 regulates prostate cancer progression in bone.

SFTA1P is a pseudogene-derived long noncoding RNA and has become a master regulator in tumor carcinogenesis and progression processes. SFTA1P has been reported as a potential diagnostic and prognostic biomarker in non-small cell lung cancer (NSCLC). The downregulation of SFTA1P in tumor tissue has been associated with poor prognosis; however, the detailed molecular mechanism and biological functions still need to be investigated. We demonstrated that SFTA1P inhibited the growth and metastasis of NSCLC in vitro and in vivo. SFTA1P had dual functions in the cytoplasm and nucleus: In the cytoplasm, SFTA1P can serve as a "sponge" for miR-665 to increase the expression level of TGFBR2; in the nucleus, SFTA1P can bind the positive transcription elongation factor b and subsequently inhibit the transcriptase activity of RNA polymerase II. The regulation of TGFBR2 and positive transcription elongation factor b via SFTA1P depends on its subcellular localization, which was affected by the status of the N6-methyladenosine RNA modification of SFTA1P. Our research demonstrated that the candidate tumor-suppressor SFTA1P is extensively involved in NSCLC, which may offer novel insights into NSCLC oncogenesis.

Implications: SFTA1P is downregulated in NSCLC and had dual functions in the cytoplasm and nucleus.

The small G-protein Rac1 is a central player in cancer progression and metastatic dissemination. Rac1 has been established as a bona fide effector of receptor tyrosine kinases, acting as a signaling node for motility, invasiveness, mitogenesis, and gene expression. Previous studies demonstrated that Rac1 is hyperactivated in aggressive cellular models of prostate cancer. In this study, we demonstrate that CRISPR/Cas9-mediated knockout of Rac1 results in impaired proliferation and migration of prostate cancer cells. Rac1-null cells display profound alterations in transcriptional programs, particularly those associated with cell adhesion and extracellular matrix regulation. Combined expression profiling and unbiased RNAi screening of Rac1 guanine nucleotide exchange factors identified VAV2 as the foremost mediator EGF-induced GTP loading onto Rac1 in prostate cancer cells. Depletion of VAV2 from prostate cancer cells significantly reduced their proliferative and migratory capacities without affecting the expression of Rac1-regulated genes, suggesting that VAV2 controls a discrete subset of Rac1-dependent cellular responses. IHC assessment in human prostate biopsies showed significant VAV2 overexpression in tumor areas. Bioinformatic analysis revealed a strong correlation between VAV2 expression and poor clinical prognosis. In addition to uncovering a prominent role for VAV2-Rac1 as an effector pathway mediating EGFR-driven proliferative and migratory responses in prostate cancer cells, our findings underscore the potential prognostic value of VAV2 in human prostate cancer progression.

Implications: This study highlights the central role of VAV2 in prostate cancer cell proliferation and migration, as well as its potential prognostic value in disease progression.

Cancer remains one of the leading causes of morbidity and mortality worldwide, necessitating the development of diverse treatment options to improve patient outcomes. The tumor microenvironment (TME) plays a critical role in determining the efficacy of these different therapies, yet the reciprocal impact of treatment on the TME, particularly the tumor immune microenvironment (TIME), remains incompletely understood. This review investigates the different effects of cancer therapies-chemotherapy, targeted therapy, immunotherapy, and radiotherapy-on immune cells within the TIME and associated extracellular vesicles (EV). The broader impact on the TME belies a complex and nuanced tumor response. These treatments have been shown to have an impact on the function of various immune cells, influencing their activity to either promote or block tumor growth. Importantly, this review also considers how these therapies play an indirect role in modulating the TIME by influencing the release and contents of EVs, highlighting the significant role that EVs play in intercellular communication within the TIME. By analyzing recent findings, this review aims to provide a comprehensive understanding of how different cancer therapies reshape the TIME. Understanding these dynamic relationships can help pave the way for optimizing existing treatments, developing new therapies, and enhancing patient outcomes.

Germline CDH1 loss-of-function mutations are causally linked to an increased lifetime risk of diffuse gastric cancer (DGC). Early, multifocal signet ring cell (SRC) lesions are ubiquitous among CDH1 variant carriers, yet only a subset of patients will develop advanced DGC. A multiomic analysis was performed to establish the molecular phenotype of early SRC lesions and how they differ from advanced DGC using 20 samples from human total gastrectomy specimens of germline CDH1 variant carriers. Spatial transcriptomic analysis demonstrated reduced CDH1 gene expression and increased expression of extracellular matrix remodeling in SRC lesions compared with unaffected adjacent gastric epithelium. Single-cell RNA sequencing revealed an SRC-enriched signature with markers REG1A, VIM, AQP5, PRR4, MUC6, and AGR2. Importantly, SRC lesions lacked alterations in known drivers of gastric cancer (TP53, ARID1A, and KRAS) and activation of associated signal transduction pathways. Advanced DGC demonstrated E-cadherin reexpression, somatic TP53 and ERBB3 mutations, and upregulated CTNNA1, MYC, and MET expression when compared with SRC lesions.

Implications: The marked differences in the genomic and transcriptomic profiles of SRC lesions and advanced DGC support the consideration of SRC lesions as precancers in patients with germline CDH1 mutations.

As a vital form of posttranscriptional modification, RNA N6-methyladenosine (m6A) methylation dysregulation is usually associated with the pathogenesis of a range of diseases, including cancer, but the function and underlying mechanisms of m6A in regulating gastric cancer initiation and progression are still poorly understood. In this study, we have found that methyltransferase-like 3 (METTL3) and the level of RNA m6A modification were significantly upregulated in gastric cancerous tissues relative to their normal counterparts. In addition, higher METTL3 expression always predicted poorer outcomes for patients with gastric cancer. Methylated RNA sequencing revealed that METTL3 deposited m6A modification on farnesyltransferase, subunit alpha (FNTA) mRNA and accelerated its translation relying on YTH N6-methyladenosine RNA-binding protein 1 recognition. When METTL3 or FNTA expression was silenced in gastric cancer cells, the FNTA-mediated KRAS plasma membrane distribution was disrupted, resulting in downstream MEK/ERK signaling inactivation, which finally contributed to gastric cancer suppression in vitro and in vivo. In summary, our studies revealed a cross-talk between METTL3-mediated RNA methylation and FNTA-mediated protein modification, which synergized to drive gastric cancer progression through orchestrating KRAS/ERK signaling activity.

Implications: Targeting the METTL3/FNTA pathway will provide an alternative to overcome the resistance of gastric cancer to canonical KRAS inhibitors.

Protein homeostasis is critical to the survival of multiple myeloma cells. Although this is targeted with proteasome inhibitors, mRNA translation inhibition has not entered trials. Recent work illustrates broad sensitivity of multiple myeloma cells to the translation inhibitor omacetaxine. We hypothesized that understanding how multiple myeloma becomes resistant will lead to the development of drug combinations to prevent or delay relapse. We generated omacetaxine resistance in H929 and MM1S multiple myeloma cell lines and compared them with parental lines. Resistant lines displayed decreased sensitivity to omacetaxine, with EC50 > 100 nmol/L, compared with parental sensitivity of 24 to 54 nmol/L. As omacetaxine inhibits protein synthesis, we performed both RNA sequencing and ribosome profiling to identify shared and unique regulatory strategies of resistance. Transcripts encoding translation factors and containing a terminal oligopyrimidine sequence in their 5' untranslated region were translationally upregulated in both resistant cell lines. The mTOR pathway promotes the translation of terminal oligopyrimidine motif-containing mRNAs. Indeed, mTOR inhibition with Torin 1 restored partial sensitivity to omacetaxine in both resistant cell lines. The combination was synergistic in omacetaxine-naïve multiple myeloma cell lines, and a combination effect was observed in vivo. Primary multiple myeloma cells from patient samples were also sensitive to the combination. These results provide a rational approach for omacetaxine-based combination therapy in patients with multiple myeloma, which have historically shown better responses to multiagent regimens.

Implications: Through the use of ribosome profiling, our findings indicate mTOR inhibition as a novel combination therapy for partnering with the translation inhibitor omacetaxine in the treatment of multiple myeloma.

New agents are needed that selectively kill cancer cells without harming normal tissues. The TRAIL ligand and its receptors, DR5 and DR4, exhibit cancer-selective toxicity. TRAIL analogs or agonistic antibodies targeting these receptors are available but have not yet received FDA approval for cancer therapy. Small molecules for activating DR5 or DR4 independently of protein ligands may activate TRAIL receptors as a monotherapy or potentiate the efficacy of TRAIL analogs and agonistic antibodies. Previously described disulfide bond-disrupting agents activate DR5 by altering its disulfide bonding through inhibition of protein disulfide isomerases ERp44, AGR2, and PDIA1. Work presented in this article extends these findings by showing that disruption of single DR5 disulfide bonds causes high-level DR5 expression, disulfide-mediated clustering, and activation of caspase 8/caspase 3-mediated proapoptotic signaling. Recognition of the extracellular domain of DR5 by various antibodies is strongly influenced by the pattern of DR5 disulfide bonding, which has important implications for the use of agonistic DR5 antibodies for cancer therapy and as research tools. Importantly, other endoplasmic reticulum (ER) stressors, including thapsigargin and tunicamycin, also alter DR5 disulfide bonding in various cancer cell lines, and in some instances, DR5 mis-disulfide bonding is potentiated by overriding the integrated stress response (ISR) with inhibitors of the PERK kinase or the ISR inhibitor ISRIB. These observations indicate that the pattern of DR5 disulfide bonding functions as a sensor of ER stress and serves as an effector of proteotoxic stress by driving extrinsic apoptosis independently of extracellular ligands.

Implications: Extreme ER stress triggers triage of transmembrane receptor production, whereby mitogenic receptors are downregulated and death receptors are simultaneously elevated.