Molecular Cancer Research最新文献

Tumor-associated macrophages (TAMs) are a transcriptionally heterogeneous population, and their abundance and function in prostate cancer is poorly defined. We integrated parallel datasets from single-cell RNA-sequencing, spatial transcriptomics and multiplex immunofluorescence to reveal the dynamics of TAMs in primary and metastatic prostate cancer. Four TAM subpopulations were identified. Notably, one of these TAM subsets was defined by the co-expression of SPP1+ and TREM2+ and was significantly enriched in metastatic tumors. The SPP1+/TREM2+ TAMs were enriched in the metastatic tumor microenvironment in both human patient samples and murine models of prostate cancer. The abundance of these SPP1+/TREM2+ macrophages was associated with patient progression free survival. Spatially, TAMs within prostate cancer bone metastases were highly enriched within the tumor region, consistent with their pro-tumorigenic role. Blocking SPP1 in RM1 prostate cancer mouse model led to improved efficacy of anti-PD-1 treatment, and increased CD8 T cell infiltration in tumor. These findings suggest that targeting SPP1+ TAMs may offer a promising therapeutic strategy and potentially enhance the effects of immune checkpoint inhibition (ICI) in advanced prostate cancer. Implications: This study expands our understanding of the diverse roles of macrophage populations in prostate cancer metastases and highlights new therapeutic targets.

Renal cell carcinoma (RCC), a prevalent urinary system malignancy, often metastasizes at an early stage. Characterized by a complex pathogenesis and high mortality rate, RCC poses a significant clinical challenge. We evaluated the expression level of EMX2 in RCC patients and revealed a significant reduction of EMX2 expression, correlating with poor RCC patient prognosis. EMX2 functions as a tumor suppressor and inhibits RCC cell proliferation and migration, accompanied by programmed cell death. Implantation of EMX2-transduced RCC cells beneath the mouse kidney capsule or subcutaneous injection of transduced RCC cells results in a reduction in tumor growth and size. Through RNA-seq and chromatin immunoprecipitation sequencing analyses, we have identified Cell Adhesion Molecule 1 (CADM1) as a direct transcriptional target of EMX2's suppressive effects. CADM1 induction by EMX2 triggers PARP1-mediated parthanatos, a specific type of cell death due to mitochondrial oxidation reduction, in migrating RCC cells. Concurrently, EMX2-CADM1 upregulation instigates Caspase-3-dependent apoptosis in attached RCC cells. Furthermore, EMX2-CADM1 transcriptional axis also inhibits the PI3K-AKT pathway to impair RCC cell growth. Hence, the orchestrated effects mediated by EMX2-CADM1 axis promote RCC cell death and suppresse its growth and invasion, providing potential intervention strategies for combating RCC. Implications: The EMX2-CADM1 transcriptional axis offers a promising therapeutic target for inducing cell death and inhibiting growth and invasion in renal cell carcinoma, which could lead to more effective treatment strategies for this aggressive malignancy.

Small-cell lung carcinoma (SCLC) tumors are heterogeneous, with a subpopulation of cells primed for tumor initiation. Here, we show that Kinase Suppressor of Ras 2 (KSR2) promotes the self-renewal and clonogenicity of SCLC cells. KSR2 is a molecular scaffold that promotes Raf/MEK/ERK signaling. KSR2 is preferentially expressed in the ASCL1 subtype of SCLC (SCLC-A) tumors and is expressed in pulmonary neuroendocrine cells, one of the identified cells of origin for SCLC-A tumors. The expression of KSR2 in SCLC and pulmonary neuroendocrine cells (PNECs) was previously unrecognized and serves as a novel model for understanding the role of KSR2-dependent signaling in normal and malignant tissues. Disruption of KSR2 in SCLC-A cell lines inhibits the colony forming ability of tumor propagating cells (TPCs) in vitro and their tumor initiating capacity in vivo. The effect of KSR2 depletion on self-renewal and clonogenicity is dependent on the interaction of KSR2 with ERK. These data indicate that the expression of KSR2 is an essential driver of SCLC-A tumor propagating cell function, and therefore may play a role in SCLC tumor initiation. These findings shed light on a novel effector promoting initiation of ASCL1-subtype SCLC tumors, and a potential subtype-specific therapeutic target. Implications: Manipulation of the molecular scaffold KSR2 in ASCL1-subtype small-cell lung cancer cells reveals its contribution to self-renewal, clonogenicity, and tumor initiation.

Multiple lines of correlative evidence support a role for ANGEL2, a novel cancer-relevant RNA-binding protein, in the modulation of chemoresistance and cancer patient survival. However, to date, no study has determined a mechanism by which ANGEL2 modulates cancer progression, nor its role in chemoresistance. Herein, we demonstrate that loss of ANGEL2 leads to a substantial decrease of the key tumor suppressor protein TP53. We show that ANGEL2 directly interacts with EIF4E, the rate limiting protein in cap-dependent translation. This interaction abrogates the ability for the TP53 translation repressor RBM38 to interact with EIF4E thereby enhancing TP53 translation. Loss of ANGEL2 in cancer cell lines resulted in increased 2D and 3D spheroid cell growth, and resistance to doxorubicin and etoposide. With therapeutic potential, treatment with Pep7, a seven amino-acid peptide derived from ANGEL2, rescued wildtype TP53 expression and sensitized cancer cells to doxorubicin. Together, we conclude that ANGEL2 modulates the EIF4E-RBM38 complex to enhance wildtype TP53 translation, and further, the Pep7 peptide may be explored as a therapeutic strategy for cancers which harbor wildtype TP53 expression. Implications: Loss of ANGEL2 contributes to decreased wildtype TP53 translation promoting doxorubicin resistance which can be rescued via an ANGEL2-derived peptide.

Protein homeostasis is critical to the survival of multiple myeloma (MM) cells. While this is targeted with proteasome inhibitors, mRNA translation inhibition has not entered trials. Recent work illustrates broad sensitivity MM cells to the translation inhibitor omacetaxine. We hypothesized that understanding how MM becomes resistant will lead to the development of drug combinations to prevent or delay relapse. We generated omacetaxine resistance in H929 and MM1S MM cell lines and compared them to parental lines. Resistant lines displayed decreased sensitivity to omacetaxine, with EC50 > 100 nM, compared to parental sensitivity of 24-54 nM. Since omacetaxine inhibits protein synthesis, we performed both RNA-sequencing and ribosome profiling (Ribo-seq) to identify shared and unique regulatory strategies of resistance. Transcripts encoding translation factors and containing Terminal OligoPyrimidine (TOP) sequence in their 5' UTR were translationally upregulated in both resistant cell lines. The mTOR pathway promotes the translation of TOP 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 MM cell lines, and a combination effect was observed in vivo. Primary MM cells from patient samples were also sensitive to the combination. These results provide a rational approach for omacetaxine-based combination in patients with multiple myeloma, which have historically shown better responses to multi-agent 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.

Patients with triple negative breast cancer (TNBC) and comorbid Type 2 Diabetes (T2D), characterized by insulin resistance of adipose tissue, have higher risk of metastasis and shorter survival. Adipocytes are the main non-malignant cells of the breast tumor microenvironment (TME). However, adipocyte metabolism is usually ignored in oncology and mechanisms that couple T2D to TNBC outcomes are poorly understood. Here we hypothesized that exosomes, small vesicles secreted by TME breast adipocytes, drive epithelial-to-mesenchymal transition (EMT) and metastasis in TNBC via miRNAs. Exosomes were purified from conditioned media of 3T3-L1 mature adipocytes, either insulin-sensitive (IS) or insulin-resistant (IR). Murine 4T1 cells, a TNBC model, were treated with exosomes in vitro (72h). EMT, proliferation and angiogenesis were elevated in IR vs. control and IS. Brain metastases showed more mesenchymal morphology and EMT enrichment in the IR group. MiR- 145a-3p is highly differentially expressed between IS and IR, and potentially regulates metastasis. Implications: IR adipocyte exosomes modify the TME, enhance EMT, and promote brain metastasis-likely via miRNA pathways-suggesting that metabolic diseases like T2D foster a pro-metastatic TME, reducing survival, warranting close monitoring and potential metabolic interventions in TNBC patients with T2D.

Methyltransferase-like 3 (METTL3) is a primary RNA methyltransferase that catalyzes N6-methyladenosine (m6A) modification. The current study aims to further delineate the effect and mechanism of METTL3 in hepatocellular carcinoma (HCC). By using a murine model of hepatocellular cancer development induced via hydrodynamic tail vein injection, we showed that METTL3 enhanced HCC development. In cultured human HCC cell lines (Huh7 and PLC/PRF/5), we observed that stable knockdown of METTL3 by short hairpin RNA significantly decreased tumor cell proliferation, colony formation, and invasion, in vitro. When Huh7 and PLC/PRF/5 cells with short hairpin RNA knockdown of METTL3 were inoculated into the livers of SCID mice, we found that METTL3 knockdown significantly inhibited the growth of HCC xenograft tumors. These findings establish METTL3 as an important oncogene in HCC. Through m6A sequencing, RNA sequencing, and subsequent validation studies, we identified BMI1 and RNF2, two key components of the polycomb repressive complex 1, as direct downstream targets of METTL3-mediated m6A modification in HCC cells. Our data indicated that METTL3 catalyzed m6A modification of BMI1 and RNF2 mRNAs which led to increased mRNA stability via the m6A reader proteins IGF2BP1/2/3. Furthermore, we showed that the METTL3 inhibitor, STM2457, significantly inhibited HCC cell growth in vitro and in mice. Collectively, this study provides novel evidence that METTL3 promotes HCC development and progression through m6A modification of BMI1 and RNF2. Our findings suggest that the METTL3-m6A-BMI1/RNF2 signaling axis may represent a new therapeutic target for the treatment of HCC. Implications: The METTL3-m6A-BMI1/RNF2 signaling axis promotes HCC development and progression.

One of the deadliest types of cancer is pancreatic ductal adenocarcinoma (PDAC). Chronic stress and obesity are recognized as risk factors for PDAC. We hypothesized that the combination of stress and obesity strongly promotes pancreatic cancer development and growth. Here, we show that the stress mediator norepinephrine and the β-adrenergic receptor agonist isoproterenol rapidly stimulate cyclic adenosine monophosphate response element-binding protein (CREB) phosphorylation at Ser133 in human PDAC cells. Exposure to the nonselective β-adrenergic receptor antagonist propranolol or selective antagonists, including nebivolol, atenolol, or ICI118551, blocked CREB phosphorylation elicited by norepinephrine or isoproterenol in PDAC cells. Stimulation of PDAC cells with neurotensin, a neuropeptide implicated in obesity and PDAC, also stimulated CREB phosphorylation at Ser133. Mechanistically, norepinephrine induced CREB phosphorylation at Ser133 via PKA, whereas neurotensin promoted CREB phosphorylation predominantly through protein kinase D. Our results indicate that CREB is a point of signal convergence that mediates proliferation in PDAC cells and raised the possibility that stress and diet cooperate in promoting PDAC in vivo. To test this notion, mice expressing KrasG12D in all pancreatic lineages (KC mice) and fed an obesogenic high fat, calorie diet that promotes early PDAC development were subjected to social isolation stress. We show that social isolation stress induced a significant increase in the proportion of advanced PDAC precursor lesions (pancreatic intraepithelial neoplasia) in KC mice subjected to an obesogenic high fat, calorie diet. Implications: Our data imply that chronic (social isolation) stress cooperates with diet-induced obesity in accelerating the development of pancreatic cancer.

Recent evidence indicates that a high-fat diet can promote tumor development, especially colorectal cancer, by influencing the microbiota. Regulatory circular RNA (circRNA) plays an important role in modulating host-microbe interactions; however, the specific mechanisms by which circRNAs influence cancer progression by regulating these interactions remain unclear. Here, we report that consumption of a high-fat diet modulates the microbiota by specifically upregulating the expression of the noncoding RNA hsa_circ_0126925 (herein, referred to as circ_0126925) in colorectal cancer. Acting as a scaffold, circ_0126925 hinders the recruitment of the E3 ubiquitin ligase tripartite motif-containing protein 21 (TRIM21) to branched-chain amino acid transaminase 2 (BCAT2), leading to reduced degradation of BCAT2. This reduction in targeted degradation of BCAT2 can protect tumors from limited branched-chain amino acid (BCAA) interference by improving the metabolism of BCAAs in colorectal cancer. Taken together, these data demonstrate that circ_0126925 plays a critical role in promoting the progression of colorectal cancer by maintaining BCAA metabolism and provide insight into the functions and crosstalk of circ_0126925 in host-microbe interactions in colorectal cancer. Implications: This study preliminarily confirms that circRNAs do indeed respond to microbiota/microbial metabolites, providing further evidence for the potential development of circRNAs as diagnostic tools and/or therapeutic agents to alleviate microbiome-related pathology in humans.

Our research aims to understand the adaptive-ergo potentially metastatic-responses of prostate cancer to changing microenvironments. Emerging evidence implicates a role of the polyaneuploid cancer cell (PACC) state in metastasis, positing the PACC state as capable of conferring metastatic competency. Mounting in vitro evidence supports increased metastatic potential of cells in the PACC state. Additionally, our recent retrospective study revealed that PACC presence in patient prostate tumors at the time of radical prostatectomy was predictive of future metastasis. To test for a causative relationship between PACC state biology and metastasis in prostate cancer, we leveraged a novel method designed for flow cytometric detection of circulating tumor cells (CTC) and disseminated tumor cells (DTC) from animal models. This approach provides both quantitative and qualitative information about the number and PACC status of recovered CTCs and DTCs. Specifically, we applied this approach to the analysis of subcutaneous, caudal artery, and intracardiac murine models. Collating data from all models, we found that 74% of recovered CTCs and DTCs were in the PACC state. Furthermore, in vivo colonization assays proved that PACC populations can regain proliferative capacity at metastatic sites. Additional in vitro analyses revealed a PACC-specific partial epithelial-to-mesenchymal transition phenotype and a prometastatic secretory profile, together providing preliminary evidence of prometastatic mechanisms specific to the PACC state. Implications: Considering that many anticancer agents induce the PACC state, our data position the increased metastatic competency of PACC state cells as an important unforeseen ramification of neoadjuvant regimens, which may help explain clinical correlations between chemotherapy and metastatic progression.