Molecular Cancer Research最新文献

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 multi-omics 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 ECM remodeling in SRC lesions compared to 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, KRAS) and activation of associated signal transduction pathways. Advanced DGC demonstrated E-cadherin re-expression, somatic TP53 and ERBB3 mutations, and upregulated CTNNA1, MYC, and MET expression when compared to SRC lesions. Implications: The marked differences in genomic and transcriptomic profile of SRC lesions and advanced DGC support the consideration of SRC lesions as precancers in patients with germline CDH1 mutations.

The malignant progression of human cancer is dictated by specific regulatory hubs coordinating multiple signaling modules. Identifying key oncogenic hubs of human cancers may lay the groundwork for developing breakthrough therapeutic strategies. Actin-like 6A (ACTL6A; BAF53A) was originally identified as a chromatin remodeling factor involved in the transcriptional regulation of genes, especially in stem and progenitor cells. The preponderance of evidence revealed the overexpression of ACTL6A in most cancers and its crucial role in various malignant phenotypes, including cell cycle progression, cancer stemness, epithelial-to-mesenchymal transition, redox and glucose metabolism, and DNA replication and repair. Interestingly, emerging data suggest that the oncogenic function of ACTL6A is mediated through diverse mechanisms beyond its canonical function in transcriptional regulation, including notably the stabilization of oncoproteins and stemness factors, such as YAP, VPS72, and MYC. Here, we describe the isoforms and the putative functional domains of ACTL6A. We summarize the expression pattern and prognostic significance of ACTL6A in human cancers and the upstream regulatory mechanisms of its expression. We summarize recent progress in understanding the diverse pro-oncogenic functions of ACTL6A and emphasize its pleiotropic mechanisms of action as a regulatory hub of cancer stemness and progression. The review highlights the importance and the potential utilities of characterizing ACTL6A, which may imply molecularly informed diagnostics and therapeutics to improve the outcome of cancer patients.

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. Here, we show that CRISPR/Cas9-based knockout of Rac1 leads to impaired prostate cancer cell proliferation and migration. Rac1-null cells display profound alterations in transcriptional programs, particularly those associated with cell adhesion and extracellular matrix (ECM) regulation. Combined expression profiling and unbiased RNAi screening of Rac1 Guanine nucleotide Exchange Factors (Rac-GEFs) identified VAV2 as the foremost mediator of epidermal growth factor (EGF)-induced GTP loading onto Rac1 in prostate cancer cells. VAV2 depletion 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. Immunohistochemical 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 VAV2's central role in prostate cancer cell proliferation and migration and its potential prognostic value in disease progression.

SFTA1P is a pseudogene-derived lncRNA 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 down-regulation 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 played 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 P-TEFb and subsequently inhibit the transcriptase activity of RNA polymerase II. The regulation of TGFBR2 and P-TEFb via SFTA1P depends on its subcellular localization, which was affected by the status of the N6-methyladenosine (m6A) RNA modification of SFTA1P. Our research demonstrated that the candidate tumor suppressor SFTA1P is extensively involved in NSCLC, which may offer novel insight into NSCLC oncogenesis. Implications: SFTA1P is down regulated in non-small cell lung cancer and played dual functions in the cytoplasm and nucleus.

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.