Molecular Cancer Research最新文献

Malignant neoplasms arise within a region of chronic inflammation, which is a key factor in all aspects of tumorigenesis including initiation, proliferation, invasion, angiogenesis, and metastasis. IL-1 plays critical functions in tumor development by influencing the tumor microenvironment and promoting cancer progression. However, the mechanism of continuous activation of the IL-1-mediated inflammatory pathway in tumors has not been fully elucidated. This study provides a novel mechanism of the autocrine activation of IL-1 signaling in squamous cell carcinoma (SCC) through a novel oncoprotein, TSC-22 homologous gene-1 (THG-1, also known as TSC22D4). The RNA sequencing analysis revealed that THG-1 overexpression enhances the transcription of NF-κB targets including IL1A, IL1B, TNFA, and IL8. Furthermore, THG-1 knockdown reduced the responsiveness to IL-1 through the suppression of NF-κB nuclear translocation. To elucidate the mechanism, we focused on a THG-1 interacting protein, NRBP1. We found that NRBP1 facilitates the degradation of TNF receptor-associated factor 6 (TRAF6) through its E3 ubiquitin ligase activity. THG-1 bound to NRBP1 and suppressed the degradation of TRAF6. Furthermore, THG-1 knockdown reduced TRAF6 abundance and NF-κB activity in SCC cells. Public database analyses of head and neck SCC revealed that high expression of THG-1 is associated with the activation of the IL-1 and TNF pathways, which share TRAF6 in the signal transductions. Finally, THG-1 abundance in laryngeal SCC specimens is elevated in patients with recurrence. These results indicated that THG-1 drives the self-sufficiency of IL-1-mediated inflammatory pathway, which could contribute to the future diagnosis and immunotherapy of SCCs. Implications: An oncoprotein, THG-1/TSC22D4 activates the IL-1-mediated inflammatory pathway through the suppression of TRAF6 degradation, which mediates the continuous inflammation in tumors.

Few treatment options are available for patients with metastatic uveal melanoma. Although the bispecific tebentafusp is FDA approved, immunotherapy has largely failed, likely given the poorly immunogenic nature of uveal melanoma. Treatment options that improve the recognition of uveal melanoma by the immune system may be key to reducing disease burden. We investigated whether uveal melanoma has the ability to undergo pyroptosis, a form of immunogenic cell death. Publicly available patient data and cell line analysis showed that uveal melanoma expressed the machinery needed for pyroptosis, including gasdermins D and E (GSDMD and E), caspases 1, 3, 4, and 8, and ninjurin-1. We induced cleavage of GSDMs in uveal melanoma cell lines treated with metabolic inhibitors. In particular, the carnitine palmitoyltransferase 1 (CPT1) inhibitor, etomoxir, induced propidium iodide uptake, caspase 3 cleavage, and the release of HMGB1 and IL-1β, indicating that the observed cleavage of GSDMs led to pyroptosis. Importantly, a gene signature reflecting CPT1A activity correlated with poor prognosis in patients with uveal melanoma and knockdown of CPT1A also induced pyroptosis. Etomoxir-induced pyroptosis was dependent on GSDME but not on GSDMD, and a pyroptosis gene signature correlated with immune infiltration and improved response to immune checkpoint blockade in a set of patients with uveal melanoma. Together, these data show that metabolic inhibitors can induce pyroptosis in uveal melanoma cell lines, potentially offering an approach to enhance inflammation-mediated immune targeting in patients with metastatic uveal melanoma. Implications: Induction of pyroptosis by metabolic inhibition may alter the tumor immune microenvironment and improve the efficacy of immunotherapy in uveal melanoma.

Elevated blood levels of estrogens have been associated with poor prognosis in estrogen receptor-positive (ER+) breast cancers, but the relationship between circulating hormone levels in the blood and intracellular hormone concentrations is not well characterized. We observed that MCF-7 cells treated acutely with 17β-estradiol (E2) retain a substantial amount of the hormone even upon the removal of the hormone from the culture medium. Moreover, global patterns of E2-dependent gene expression are sustained for hours after acute E2 treatment and hormone removal. Although circulating E2 is sequestered by sex hormone binding globulin, the potential mechanisms of intracellular E2 retention are poorly understood. We found that mislocalization of a steroid-binding GRAM domain-containing protein, ASTER-B, to the nucleus, which is observed in a subset of patients with breast cancer, is associated with higher cellular E2 retention. Accumulation and retention of E2 are related to the steroidal properties of E2 and require nuclear localization and steroid binding by ASTER-B, as shown using a panel of mutant ASTER-B proteins. Finally, we observed that nuclear ASTER-B-mediated E2 retention is required for sustained hormone-induced ERα chromatin occupancy at enhancers and gene expression, as well as subsequent cell growth responses. Our results add intracellular hormone retention as a mechanism controlling E2-dependent gene expression and downstream biological outcomes. Implications: Mislocalized nuclear ASTER-B, which binds estradiol to support the functions of ER, can provide an alternate means of enhancing the biological effects of E2 in breast cancers and may be a potential therapeutic target that addresses multiple aspects of estrogen bioavailability.

BRAF mutations in colorectal cancer comprise three functional classes: class 1 (V600E) with strong constitutive activation, class 2 with pathogenic kinase activity lower than that of class 1, and class 3 which paradoxically lacks kinase activity. Non-class 1 mutations associate with better prognosis, microsatellite stability, distal tumor location, and better anti-EGFR response. An analysis of 13 colorectal cancer cohorts (n = 6,605 tumors) compared class 1 (n = 709, 10.7% of colorectal cancers), class 2 (n = 31, 0.47%), and class 3 (n = 81, 1.22%) mutations. Class 2-mutant and class 3-mutant colorectal cancers frequently co-occurred with additional Ras pathway mutations (29.0% and 45.7%, respectively, vs. 2.40% in class 1; P < 0.001), often at atypical sites (KRAS noncodon 12/13/61, NRAS, or NF1). Ras pathway activation was highest in class 1 and lowest in class 3, with a greater distal expression of EGFR ligands (amphiregulin/epiregulin) supporting weaker BRAF driver mutations. Unlike class 1 mutants, class 3 tumors resembled chromosomally unstable colorectal cancers in mutation burdens, signatures, driver mutations, and transcriptional subtypes, whereas class 2 mutants displayed intermediate characteristics. Atypical BRAF mutations were associated with longer overall survival than class 1 mutations (HR = 0.25; P = 0.011) but lost this advantage in cancers with additional Ras mutations (HR = 0.94; P = 0.86). This study supports the suggestion that class 3 BRAF mutations amplify existing Ras signaling in a two-mutation model and that the enhancement of weak/atypical Ras mutations may suffice for tumorigenesis, with potentially clinically important heterogeneity in the class 2/3 subgroup. Implications: The heterogeneous nature of BRAF-mutant colorectal cancers, particularly among class 2/3 mutations which frequently harbor additional Ras mutations, highlights the necessity of comprehensive molecular profiling.

WD repeat domain 77 protein (WDR77), a WD-40 domain-containing protein, is a crucial regulator of cellular pathways in cancer progression. Although much of the past research on WDR77 has focused on its interaction with protein arginine methyltransferase 5 (PRMT5) in histone methylation, WDR77's regulatory functions extend beyond this pathway, influencing diverse mechanisms such as mRNA translation, chromatin assembly, cell-cycle regulation, and apoptosis. WDR77 is a key regulator of cell-cycle progression, regulating the transition from the G1 phase. WDR77 regulates many signaling pathways such as TGFβ in which its role in these cellular pathways underscores its broad oncogenic potential. WDR77 also assists and promotes certain transcription factors such as E2F. Furthermore, in certain cancers, WDR77 enhances steroid hormone receptor activity, uniquely linking it to hormone-driven malignancies. WDR77 often translocates between the nucleus and the cytoplasm, with its location dictating its role in the cell. WDR77 has the ability to adapt its function depending on its location that emphasizes its dynamic role in both promoting and inhibiting tumor growth, depending on cellular context. This dual function makes WDR77 an attractive therapeutic target, as disrupting its interactions with critical signaling pathways or modulating its translocation could yield novel strategies for cancer treatment. Given WDR77's role in oncogenic pathways independent of PRMT5, further exploration of WDR77 and its non-PRMT5-related activities may reveal additional therapeutic opportunities in an array of cancers.

The complex composition and dynamic change of the tumor microenvironment (TME), mainly consisting of tumor cells, immune cells, stromal cells, and extracellular components, significantly impede the effector function of cytotoxic T lymphocytes (CTL), thus representing a major obstacle for tumor immunotherapies. In this review, we summarize and discuss the impacts and underlying mechanisms of major elements in the TME (different cell types, extracellular matrix, nutrients and metabolites, etc.) on the infiltration, survival, and effector functions of T cells, mainly CD8+ CTLs. Moreover, we also highlight recent advances that may potentiate endogenous antitumor immunity and improve the efficacy of T cell-based immunotherapies in patients with cancer by manipulating components inside/outside of the TME. A deeper understanding of the effects and action mechanisms of TME components on the tumor-eradicating ability of CTLs may pave the way for discovering new targets to augment endogenous antitumor immunity and for designing combinational therapeutic regimens to enhance the efficacy of tumor immunotherapies in the clinic.

Esophageal squamous cell carcinoma (ESCC) remains a global health challenge. Circadian clock and maternal embryonic leucine zipper kinase (MELK) play a key role in tumorigenesis. However, a link between circadian clock dysregulation and MELK function in the occurrence and development of ESCC remains elusive. Here, In the in vivo and in vitro systems, we found for the first time that MELK exhibits pronounced circadian rhythms expression in mice esophageal tissue, xenograft model, and human ESCC cells. The diurnal differences expression between peak (ZT0) and trough (ZT12) points in normal esophageal tissue is nearly 10-fold. Circadian expression of MELK in ESCC cells was regulated by Bmal1 through binding to the MELK promoter. Supporting this, the levels of MELK were increased significantly in patients with ESCC and were accompanied by altered expression of core clock genes, especially, since Bmal1 is prominently upregulated. Most importantly, Bmal1-deleted eliminated the rhythmic expression of MELK, whereas the knockdown of other core genes had no effect on MELK expression. Furthermore, in nude mice with transplanted tumors, the anticancer effect of OTS167 at ZT0 administration is twice that of ZT12. Implications: Our findings suggest that MELK represents a therapeutic target, and can as a regulator of circadian control ESCC growth, with these findings advance our understanding of the clinical potential of chronotherapy and the importance of time-based MELK inhibition in cancer treatment.

Prostate cancer is mainly managed with androgen deprivation therapy (ADT), but this often leads to a dormant state and subsequent relapse as lethal castration-resistant prostate cancer (CRPC). Using our unique prostate cancer patient-derived xenograft dormancy models, we investigated this critical dormant phase and discovered a selective increase in B7-H4 expression during the dormancy period following mouse host castration. This finding is supported by observations in clinical specimens of patients with prostate cancer treated with ADT. Differential expression analyses revealed the enrichment of extracellular matrix (ECM)-cell interaction pathways in B7-H4-positive cells. Functional assays demonstrated a crucial role of B7-H4 in maintaining dormancy within the ECM niche. Specifically, B7-H4 expression in LNCaP cells reduced proliferation within the dormant ECM in vitro and significantly delayed relapse in castrated hosts in vivo. These results shed light on the dynamic regulation of B7-H4 during prostate cancer dormancy and underscore its potential as a therapeutic target for preventing CRPC relapse. Implications: Our study identified membranous B7-H4 expression during ADT-induced dormancy, highlighting its potential as a therapeutic target for managing dormant prostate cancer and preventing fatal CRPC relapse.

Communication between intracellular organelles including lysosomes and mitochondria has recently been shown to regulate cellular proliferation and fitness. The way lysosomes and mitochondria communicate with each other [lysosomal-mitochondrial interaction (LMI)] is emerging as a major determinant of tumor proliferation and growth. About 30% of squamous carcinomas [including squamous cell carcinoma of the head and neck (SCCHN)] overexpress transmembrane member 16A (TMEM16A), a calcium-activated chloride channel, which promotes cellular growth and negatively correlates with patient survival. We have recently shown that TMEM16A drives lysosomal biogenesis; however, its impact on mitochondrial function has not been explored. In this study, we show that in the context of high-TMEM16A SCCHN, (i) patients display increased mitochondrial content, specifically complex I; (ii) in vitro and in vivo models uniquely depend on mitochondrial complex I activity for growth and survival; (iii) NRF2 signaling is a critical linchpin that drives mitochondrial function, and (iv) mitochondrial complex I and lysosomal function are codependent for proliferation. Taken together, our data demonstrate that coordinated lysosomal and mitochondrial activity and biogenesis via LMI drive tumor proliferation and facilitate a functional interaction between lysosomal and mitochondrial networks. Therefore, inhibition of LMI instauration may serve as a therapeutic strategy for patients with SCCHN. Implications: Intervention of LMI may serve as a therapeutic approach for patients with high TMEM16A-expressing SCCHN.