Molecular Cancer Research最新文献

WD repeat domain 77 protein (WDR77), a WD-40 domain-containing protein, is a crucial regulator of cellular pathways in cancer progression. While much of the past research on WDR77 has focused on its interaction with 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 where 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 which 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.

Epidermal growth factor receptor (EGFR) is a highly expressed driver of many cancers, yet the utility of EGFR inhibitors is limited to cancers that harbor sensitizing mutations in the EGFR gene due to dose limiting toxicities. Rather than conventionally blocking the kinase activity of EGFR, we sought to reduce its transcription as an alternative approach to broaden the therapeutic window for EGFR inhibitors targeting wildtype or mutant EGFR. We found that YES1 is highly expressed in triple negative breast cancer (TNBC) and drives cell growth by elevating EGFR levels. Mechanistically, YES1 stimulates EGFR expression by signaling to JNK and stabilizing the AP-1 transcription factor, c-Jun. This effect extends beyond TNBC as YES1 also sustains EGFR expression in non-small cell lung cancer (NSCLC) cells, including those that harbor the EGFR gatekeeper mutation, T790M. The novel ability of YES1 to regulate the expression of wildtype and mutant EGFR mRNA and protein provides a potential therapeutic opportunity of utilizing YES1 blockade to broadly increase the efficacy of EGFR inhibitors. Indeed, we found synergy within in vitro and in vivo models of TNBC and NSCLC, even in the absence of EGFR activating mutations. Together, these data provide a rationale for blocking YES1 activity as an approach for improving the efficacy of EGFR-targeting drugs in cancers that have generally been refractory to such inhibitors. Implications: YES1 sustains EGFR expression, revealing a therapeutic vulnerability for increasing the efficacy of EGFR inhibitors by lowering the threshold for efficacy in tumors driven by wildtype or mutant receptor.

Breast cancers of the IntClust-2 type, characterized by amplification of a small portion of chromosome 11, have a median survival of only five years. Several cancer-relevant genes occupy this portion of chromosome 11, and it is thought that overexpression of a combination of driver genes in this region is responsible for the poor outcome of women in this group. In this study we used a gene editing method to knock out, one by one, each of 198 genes that are located within the amplified region of chromosome 11 and determined how much each of these genes contributed to the survival of breast cancer cells. In addition to well-known drivers such as CCND1 and PAK1, we identified two different genes (SERPINH1 and P4HA3), that encode proteins involved in collagen synthesis and organization. Using both in vitro and in vivo functional analyses, we determined that P4HA3 and/or SERPINH1 provide a critical driver function on IntClust-2 basic processes, such as viability, proliferation, and migration. Inhibiting these enzymes via genetic or pharmacologic means reduced collagen synthesis and impeded oncogenic signaling transduction in cell culture models, and a small-molecule inhibitor of P4HA3 was effective in treating 11q13 tumor growth in an animal model. As collagen has a well-known association with tissue stiffness and aggressive forms of breast cancer, we believe that the two genes we identified provide an opportunity for a new therapeutic strategy in IntClust-2 breast cancers. Implications: Breast cancers with 11q13/14 chromosomal amplifications may be vulnerable to inhibitors of collagen synthesis.

Elevated blood levels of estrogens are associated with poor prognosis in estrogen receptor-positive (ER+) breast cancers, but the relationship between circulating blood hormone levels and intracellular hormone concentrations are not well characterized. We observed that MCF-7 cells treated acutely with 17β-estradiol (E2) retain a substantial amount of the hormone even upon 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. While circulating E2 is sequestered by sex hormone binding globulin (SHBG), the potential mechanisms of intracellular E2 retention are poorly understood. We found that a mislocalization of a steroid-binding GRAM-domain containing protein, ASTER-B, to the nucleus, which is observed in a subset of breast cancer patients, 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 ERalpha 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.

Prostate cancer (PCa) 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 PCa patient-derived xenograft (PDX) 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 PCa patients 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 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 PCa 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.

Although early prostate cancer depends on the androgen receptor signaling pathway, which is predominant in luminal cells, there is much to be understood about the contribution of epithelial basal cells in cancer progression. Herein, we observe cell type-specific differences in the importance of the metabolic enzyme phosphatidylinositol 5-phosphate 4-kinase alpha (PI5P4Kα; gene name PIP4K2A) in the prostate epithelium. We report the development of a basal cell-specific genetically engineered mouse model targeting Pip4k2a alone or in combination with the tumor suppressor phosphatase and tensin homolog (Pten). PI5P4Kα is enriched in basal cells, and no major histopathologic changes were detectable following gene deletion. Notably, the combined loss of Pip4k2a slowed the development of Pten mutant mouse prostatic intraepithelial neoplasia. Through the inclusion of a lineage tracing reporter, we utilize single-cell RNA sequencing to evaluate changes resulting from in vivo downregulation of Pip4k2a and characterize cell populations influenced in the established Probasin-Cre- and cytokeratin 5-Cre-driven genetically engineered mouse model. Transcriptomic pathway analysis points toward the disruption of lipid metabolism as a mechanism for reduced tumor progression. This was functionally supported by shifts of carnitine lipids in LNCaP prostate cancer cells treated with siPIP4K2A. Overall, these data nominate PI5P4Kα as a target for PTEN mutant prostate cancer. Implications: PI5P4Kα is enriched in prostate basal cells, and its targeted loss slows the progression of a model of advanced prostate cancer.

Dietary exposure to aflatoxin B1 (AFB1) is a risk factor for the development of hepatocellular carcinomas. Following metabolic activation, AFB1 reacts with guanines to form covalent DNA adducts, which induce high-frequency G > T transversions. The molecular signature associated with these mutational events aligns with the single-base substitution signature 24 (SBS24) in the Catalog of Somatic Mutations in Cancer database. Deficiencies in either base excision repair due to the absence of Nei-like DNA glycosylase 1 (NEIL1) or nucleotide excision repair due to the absence of xeroderma complementation group A protein (XPA) contribute to hepatocellular carcinomas in murine models. In the current study, ultra-low error duplex sequencing was used to characterize mutational profiles in liver DNAs of NEIL1-deficient, XPA-deficient, and DNA repair-proficient mice following neonatal injection of 1 mg/kg AFB1. Analyses of AFB1-induced mutations showed high cosine similarity to SBS24 regardless of repair proficiency status. The absence of NEIL1 resulted in an approximately 30% increase in the frequency of mutations, with the distribution suggesting preferential NEIL1-dependent repair of AFB1 lesions in open chromatin regions. A trend of increased mutagenesis was also observed in the absence of XPA. Consistent with the role of XPA in transcription-coupled repair, mutational profiles in XPA-deficient mice showed disruption of the transcriptional bias in mutations associated with SBS24. Implications: Our findings define the roles of DNA repair pathways in AFB1-induced mutagenesis and carcinogenesis in murine models, with these findings having implications in human health for those with base excision repair and nucleotide excision repair deficiencies.

Prostate cancer is a heterogeneous disease with a spectrum of pathology and outcomes ranging from indolent to lethal. Although there have been recent advancements in prognostic tissue biomarkers, limitations still exist. We leveraged matrix-assisted laser desorption/ionization imaging of formalin-fixed, paraffin embedded prostate cancer specimens to determine if N-linked glycans expressed in the extracellular matrix of lethal neuroendocrine prostate cancer were also expressed in conventional prostate adenocarcinomas that were associated with poor outcomes. We found that N-glycan fucosylation was abundant in neuroendocrine prostate cancer as well as adenocarcinomas at the time of prostatectomy that eventually developed recurrent metastatic disease. Analysis of patient-derived xenografts revealed that this fucosylation signature was enriched differently across metastatic disease organ sites, with the highest abundance in liver metastases. These data suggest that N-linked fucosylated glycans could be an early tissue biomarker for poor prostate cancer outcomes. Implications: These studies identify that hyper-fucosylated N-linked glycans are enriched in neuroendocrine prostate cancer and conventional prostate adenocarcinomas that progress to metastatic disease, thus advancing biomarker discovery and providing insights into mechanisms underlying metastatic disease.

Gram-negative (G-) microflora dysbiosis occurs in multiple digestive tumors and is found to be the dominant microflora in the esophageal squamous cell carcinoma (ESCC) microenvironment. The continuous stimulation of G- bacterium metabolites may cause tumorigenesis and reshape the microimmune environment in ESCC. However, the mechanism of G- bacilli causing immune evasion in ESCC remains underexplored. We identified CC chemokine receptor 1 (CCR1) as a tumor-indicating gene in ESCC. Interestingly, expression levels of CCR1 and PD-L1 were mutually upregulated after G- bacilli metabolite lipopolysaccharide stimulation. First, we found that CCR1 high expression levels were associated with poor overall survival in ESCC. Importantly, we found that high levels of CCR1 expression upregulated PD-L1 expression by activating MAPK phosphorylation in ESCC and induced tumor malignant behavior. Finally, we found that T-cell exhaustion and cytotoxicity suppression were associated with CCR1 expression in ESCC, which were decreased after CCR1 inhibiting. Our work identifies CCR1 as a potential immune check point regulator of PD-L1 and may cause T-cell exhaustion and cytotoxicity suppression in ESCC microenvironment and highlights the potential value of CCR1 as a therapeutic target of immunotherapy. Implications: The esophageal microbial environment and its metabolites significantly affect the outcome of immunotherapy for ESCC.

Aberrant mitosis can result in aneuploidy and cancer. The small GTPase, Ras-related nuclear protein (Ran), is a key regulator of mitosis. B-type plexins regulate Ran activity by acting as RanGTPase-activating proteins and have been implicated in cancer progression. However, whether B-type plexins have a role in mitosis has not so far been investigated. We show here that Plexin B1 functions in the control of mitosis. Depletion of Plexin B1 affects mitotic spindle assembly, significantly delaying anaphase. This leads to mitotic catastrophe in some cells and prolonged application of the spindle assembly checkpoint. Plexin B1 depletion also promoted acentrosomal microtubule nucleation and defects in spindle pole refocusing and increased the number of cells with multipolar or aberrant mitotic spindles. An increase in lagging chromosomes or chromosomal bridges at anaphase was also found upon Plexin B1 depletion. Plexin B1 localizes to the mitotic spindle in dividing cells. The mitotic defects observed upon Plexin B1 depletion were rescued by an RCC1 inhibitor, indicating that Plexin B1 signals, via Ran, to affect mitosis. These errors in mitosis generated multinucleate cells and nuclei of altered morphology and abnormal karyotype. Furthermore, semaphorin 4D treatment increased the percentage of cells with micronuclei, precursors of chromothripsis. Implications: Defects in B-type plexins may contribute to the well-established role of plexins in cancer progression by inducing chromosomal instability.