Oncogenesis最新文献

Desmoplastic small round cell tumor (DSRCT) is an aggressive pediatric cancer caused by the EWSR1-WT1 fusion oncoprotein. The tumor is refractory to treatment with a 5-year survival rate of only 15-25%, necessitating the development of novel therapeutics, especially those able to target chemoresistant subpopulations. Novel in vitro cancer stem cell-like (CSC-like) culture conditions increase the expression of stemness markers (SOX2, NANOG) and reduce DSRCT cell line susceptibility to chemotherapy while maintaining the ability of DSRCT cells to form xenografts. To gain insights into this chemoresistant model, RNA-seq was performed to elucidate transcriptional alterations between DSRCT cells grown in CSC-like spheres and normal 2-dimensional adherent state. Commonly upregulated and downregulated genes were identified and utilized in pathway analysis revealing upregulation of pathways related to chromatin assembly and disassembly and downregulation of pathways including cell junction assembly and extracellular matrix organization. Alterations in chromatin assembly suggest a role for epigenetics in the DSRCT CSC-like state, which was further investigated with ATAC-seq, identifying over 10,000 differentially accessible peaks, including 4444 sphere accessible peaks and 6,120 adherent accessible peaks. Accessible regions were associated with higher gene expression, including increased accessibility of the CSC marker SOX2 in CSC-like culture conditions. These analyses were further utilized to identify potential CSC therapeutic targets, leading to the identification of B-lymphocyte kinase (BLK) as a CSC-enriched, EWSR1-WT1-regulated, druggable target. BLK inhibition and knockdown reduced CSC-like properties, including abrogation of tumorsphere formation and stemness marker expression. Importantly, BLK knockdown reduced DSRCT CSC-like cell chemoresistance, making its inhibition a promising target for future combination therapy.

Throughout an individual's life, somatic cells acquire cancer-associated mutations. A fraction of these mutations trigger tumour formation, a phenomenon partly driven by the interplay of mutant and wild-type cell clones competing for dominance; conversely, other mutations function against tumour initiation. This mechanism of 'cell competition', can shift clone dynamics by evaluating the relative status of clonal populations, promoting 'winners' and eliminating 'losers'. This review examines the role of cell competition in the context of tumorigenesis, tumour progression and therapeutic intervention.

We previously described a nucleolar protein RSL1D1 but distributed throughout the nucleus in HCT116 colorectal cancer (CRC) cells to facilitate G1/S transition by inhibiting p53 signaling. Here, we found another nucleolar protein, programmed cell death 11 (PDCD11), also with an “Extra-nucleolar” localization in CRC cells but to regulate G2/M checkpoint. This protein directly interacts with p53 and HDM2 in the nucleoplasm, thereby recruiting p53 to HDM2 for ubiquitination and degradation. The ensuing downregulation of p53 increases the CDK1 level to help the cells pass G2/M checkpoint. Upon DNA damage stress, PDCD11 gains the power to upregulate CDK1 independently of p53. Beyond these, PDCD11 also upregulates CDC25C in a p53-independent manner to dephosphorylate CDK1 to facilitate G2/M transition. Downregulation of PDCD11 greatly reduced cancer cell growth in vitro and in vivo, additionally sensitized cells to DNA damage signals, highlighting that PDCD11 is a crucial driving factor of CRC and a potential target for cancer treatment.

Although the transcriptional regulation of the programmed death ligand 1 (PD-L1) promoter has been extensively studied, the transcription factor residing in the PD-L1 super-enhancer has not been comprehensively explored. Through saturated CRISPR-Cas9 screening of the core region of the PD-L1 super-enhancer, we have identified a crucial genetic locus, referred to as locus 22, which is essential for PD-L1 expression. Locus 22 is a potential binding site for NFE2:MAF transcription factors. Although genetic silencing of NRF2 (NFE2L2) did not result in a reduction of PD-L1 expression, further analysis reveals that MAFG and NFE2L1 (NRF1) play a critical role in the expression of PD-L1. Importantly, lipopolysaccharides (LPS) as the major component of intratumoral bacteria could greatly induce PD-L1 expression, which is dependent on the PD-L1 super-enhancer, locus 22, and NFE2L1/MAFG. Mechanistically, genetic modification of locus 22 and silencing of MAFG greatly reduce BRD4 binding and loop formation but have minimal effects on H3K27Ac modification. Unlike control cells, cells with genetic modification of locus 22 and silencing of NFE2L1/MAFG failed to escape T cell-mediated killing. In breast cancer, the expression of MAFG is positively correlated with the expression of PD-L1. Taken together, our findings demonstrate the critical role of locus 22 and its associated transcription factor NFE2L1/MAFG in super-enhancer- and LPS-induced PD-L1 expression. Our findings provide new insight into understanding the regulation of PD-L1 transcription and intratumoral bacteria-mediated immune evasion.

Among follicular-derived thyroid cancers (TC), those with aggressive behavior and resistance to current treatments display poor prognosis. NF-κB signaling pathways are involved in tumor progression of various cancers. Here, we finely characterize the NF-κB pathways and their involvement in TC. By using immunoblot and gel shift assays, we demonstrated that both classical and alternative NF-κB pathways are activated in ten TC-derived cell lines, leading to activated RelA/p50 and RelB/p50 NF-κB dimers. By analyzing the RNAseq data of the large papillary thyroid carcinoma (PTC) cohort from The Cancer Genome Atlas (TCGA) project, we identified a tumor progression-related NF-κB signature in BRAF^V600E mutated-PTCs. That corroborated with the role of RelA and RelB in cell migration and invasion processes that we demonstrated specifically in BRAF^V600E mutated-cell lines, together with their role in the control of expression of genes implicated in invasiveness (MMP1, PLAU, LCN2 and LGALS3). We also identified NF-κB-inducing kinase (NIK) as a novel actor of the constitutive activation of the NF-κB pathways in TC-derived cell lines. Finally, its implication in invasiveness and its overexpression in PTC samples make NIK a potential therapeutic target for advanced TC treatment.

The mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway is frequently reported to be hyperactivated in hepatocellular carcinoma (HCC) and contributes to HCC recurrence. However, the underlying regulatory mechanisms of mTORC1 signaling in HCC are not fully understood. In the present study, we found that the expression of kinesin family member 18B (KIF18B) was positively correlated with mTORC1 signaling in HCC, and the upregulation of KIF18B and p-mTOR was associated with a poor prognosis and HCC recurrence. Utilizing in vitro and in vivo assays, we showed that KIF18B promoted HCC cell proliferation and migration through activating mTORC1 signaling. Mechanistically, we identified Actin gamma 1 (γ-Actin) as a binding partner of KIF18B. KIF18B and γ-Actin synergistically modulated lysosome positioning, promoted mTORC1 translocation to lysosome membrane, and prohibited p70 S6K from entering lysosomes for degradation, which finally led to the enhancement of mTORC1 signaling transduction. Moreover, we found that KIF18B was a direct target of Forkhead box M1, which explains the potential mechanism of KIF18B overexpression in HCC. Our study highlights the potential of KIF18B as a therapeutic target for the treatment of HCC.

There is a critical need to identify new therapeutic vulnerabilities in pancreatic ductal adenocarcinoma (PDAC). Transcriptional co-regulators C-terminal binding proteins (CtBP) 1 and 2 are highly overexpressed in human PDAC, and CRISPR-based homozygous deletion of Ctbp2 in a mouse PDAC cell line (CKP) dramatically decreased tumor growth, reduced metastasis, and prolonged survival in orthotopic mouse allografts. Transcriptomic profiling of tumors derived from CKP vs. Ctbp2-deleted CKP cells (CKP/KO) revealed significant downregulation of the EGFR-superfamily receptor Erbb3, the heterodimeric signaling partner for both EGFR and ErbB2. Compared with CKP cells, CKP/KO cells also demonstrated reduced Erbb2 expression and did not activate downstream Akt signaling after stimulation of Erbb3 by its ligand neuregulin-1. ErbB3 expression in human PDAC cell lines was similarly dependent on CtBP2 and depletion of ErbB3 in a human PDAC cell line severely attenuated growth, demonstrating the critical role of ErbB3 signaling in maintaining PDAC cell growth. Sensitivity to the ErbB2-targeted tyrosine kinase inhibitor lapatinib, but not the EGFR-targeted agent erlotinib, varied in proportion to the level of ErbB3 expression in mouse and human PDAC cells, suggesting that an ErBb2 inhibitor can effectively leverage CtBP2-driven transcriptional activation of physiologic ErbB2/3 expression and signaling in PDAC cells for therapeutic benefit.

Triple negative breast cancer (TNBC) is defined as lacking the expressions of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). TNBC patients exhibit relatively poor clinical outcomes due to lack of molecular markers for targeted therapies. As such chemotherapy often remains the only systemic treatment option for these patients. While chemotherapy can initially help shrink TNBC tumor size, patients eventually develop resistance to drug, leading to tumor recurrence. We report a combined in vitro/in vivo genome-wide CRISPR synthetic lethality screening approach in a relevant TNBC cell line model to identify several targets responsible for the chemotherapy drug, paclitaxel resistance. Computational analysis integrating in vitro and in vivo data identified a set of genes, for which specific loss-of-function deletion enhanced paclitaxel resistance in TNBC. We found that several of these genes (ATP8B3, FOXR2, FRG2, HIST1H4A) act as cancer stemness negative regulators. Finally, using in vivo orthotopic transplantation TNBC models we showed that FRG2 gene deletion reduced paclitaxel efficacy and promoted tumor metastasis, while increasing FRG2 expression by means of CRISPR activation efficiently sensitized TNBC tumors to paclitaxel treatment and inhibited their metastatic abilities. In summary, the combined in vitro/in vivo genome-wide CRISPR screening approach proved effective as a tool to identify novel regulators of paclitaxel resistance/sensitivity and highlight the FRG2 gene as a potential therapeutical target overcoming paclitaxel resistance in TNBC.

Although many studies have compared tumor fibroblasts (T-Fbs) and nontumor fibroblasts (N-Fbs), less is understood about the stromal contribution of metastatic lymph node fibroblasts (LN-Fbs) to the evolving microenvironment. Here, we explored the characteristics of LN-Fbs in esophageal squamous cell carcinoma (ESCC) and the interactions between fibroblasts and ESCC tumor cells in metastatic lymph nodes. Fibroblasts were isolated from tumor, nontumor and metastatic lymph node tissues from different patients with ESCC. Transcriptome sequencing was performed on the fibroblasts. Tumor growth and drug-resistance assays were carried out, and characteristics of T-Fbs, N-Fbs and LN-Fbs were determined. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to assay the culture medium of fibroblasts. The results demonstrated that fibroblasts derived from different tissues had different characteristics. Coculture with LN-Fbs conditioned medium inhibited ESCC tumor cell growth and induced chemoresistance in ESCC cells. LN-Fbs induced chemoresistance to cisplatin in ESCC cells by secreting PI16. Coculture with LN-Fbs conditioned medium decreased cisplatin-induced apoptosis in ESCC cells by regulating the p38 and JNK cell signaling pathways. Survival analyses showed that patients with high PI16 expression in Fbs of lymph nodes exhibited worse overall survival. We also examined PI16 expression in interstitial tissues in ESCC tumor samples of patients receiving platinum-based therapy postsurgery and found that high PI16 expression in tumor interstitial tissues was an independent prognostic factor for ESCC patients. In addition, an in vivo assay demonstrated that PI16 knockdown increased the sensitivity of ESCC cells to cisplatin. Our results suggest that fibroblasts in metastatic lymph nodes decrease apoptosis of ESCC cells via PI16, thereby providing a cisplatin-resistance niche and supporting ESCC tumor cells to survive in metastatic lymph nodes. PI16 is also a potential target for effectively blocking the chemoresistance niche signaling circuit in response to cisplatin.