Molecular Cancer Research最新文献

The most widely used cell line for studying ductal carcinoma in situ (DCIS) premalignancy is the transformed breast epithelial cell line, MCF10DCIS.com. During its original clonal isolation and selection, MCF10DCIS.com acquired a heterozygous M452I mutation in the proprotein convertase PCSK5, which has never been reported in any human cancer. The mutation is noteworthy because PCSK5 matures GDF11, a TGFβ-superfamily ligand that suppresses progression of triple-negative breast cancer. We asked here whether PCSK5M452I and its activity toward GDF11 might contribute to the unique properties of MCF10DCIS.com. Using an optimized in-cell GDF11 maturation assay, we found that overexpressed PCSK5M452I was measurably active but at a fraction of the wildtype enzyme. In a PCSK5-/- clone of MCF10DCIS.com reconstituted with different PCSK5 alleles, PCSK5M452I was mildly defective in anterograde transport. However, the multicellular organization of PCSK5M452I addback cells in 3D matrigel cultures was significantly less circumscribed than wildtype and indistinguishable from a PCSK5T288P null allele. Growth of intraductal MCF10DCIS.com xenografts was similarly impaired along with the frequency of comedo necrosis and stromal activation. In no setting did PCSK5M452I exhibit gain-of-function activity, leading us to conclude that it is hypomorphic and thus compensated by the remaining wildtype allele in MCF10DCIS.com. Implications: This work reassures that an exotic PCSK5 mutation is not responsible for the salient characteristics of the MCF10DCIS.com cell line.

Castration-resistant prostate cancer (CRPC), an advanced stage of prostate cancer (PCa), often leads to fatal bone metastasis. The vast majority of PCa patients who present with bone metastases suffer from bone lesions and other complications. Androgen receptor (AR) inhibitors, while improved, lack curative efficacy, necessitating an urgent demand for the development of innovative therapeutic strategies. TRIM28, also known as KAP1, is a transcription factor regulated by site-specific phosphorylation. Our recent study demonstrated that RSK1 is the protein kinase that directly phosphorylates TRIM28 at S473; as such, pS473-TRIM28 promotes the transcriptional activation of its gene targets. In this study, we reveal that TRIM28 S473 phosphorylation is readily detected in CRPC bone metastases, which is consistent with the previous report that RSK kinase is activated in PCa bone metastases. Using bioinformatic and genomic analysis, we uncovered that lactate dehydrogenase A (LDHA) is a novel TRIM28-induced gene in bone metastatic PCa. TRIM28 promotes the transcriptional activation of LDHA in a pS473-TRIM28 dependent manner. As such, TRIM28 is involved in LDH-related activities including lactate production and glycolysis. We also demonstrate that the TRIM28-LDHA axis is required for prostate tumor progression using an orthotopic bone injection model. Lastly, the application of an LDH inhibitor mitigates PCa development in bone. In summary, our study reveals an important role of the TRIM28-LDHA axis in PCa progression in bone, which may be targeted to mitigate the disease in the metastasis stage. Implications: TRIM28 upregulates LDHA and glycolysis, propelling prostate tumors in bone; pharmacologic LDH blockade mitigates disease.

A high therapeutic index, defined as potent inhibition of oncogenic signaling in tumor cells with minimal effects on normal cells, is critical for effective cancer therapies. Recent advances have introduced diverse RAS-targeting inhibitors, including mutant-specific inhibitors such as KRAS G12C and KRAS G12D, as well as paralog- and state-selective inhibitors. Non-mutant-specific RAS inhibition can be achieved by: (1) guanine nucleotide exchange-OFF inhibitors that indirectly inactivate RAS by targeting SHP2 or SOS1, (2) KRAS-OFF inhibitors that spare NRAS and HRAS, and (3) active-state RAS(ON) inhibitors that directly block binding of effector RAF. However, the signaling inhibition index (SII)-the differential suppression of oncogenic signaling between RAS-mutant and normal cells-remains poorly defined for these approaches. We evaluated the SII for state- and paralog-selective RAS inhibitors across diverse RAS-mutant and RAS-wild-type models. Guanine nucleotide exchange-OFF inhibitors exhibited neutral or negative values, with reduced MAPK suppression in KRAS G12X cells compared to wild-type cells. KRAS G13D models, especially with NF1 loss, showed low sensitivity. SHP2 plus MEK inhibition resulted in low selectivity, and RAS Q61X models were resistant due to MEK inhibitor-induced NRAS reactivation and altered SHP2 conformations. KRAS-OFF inhibitors demonstrated higher selectivity, while active-state RAS(ON) inhibitors showed broader activity but narrow selectivity. Sensitivity to mutant-specific inhibitors largely overlapped with sensitivity to state-selective agents, suggesting that most RAS-mutant tumors will respond poorly to any currently available RAS inhibitor. Implications: Determining the signaling inhibition index (SII) can inform the design and clinical application of RAS-targeted therapies to improve tumor selectivity and therapeutic outcomes.

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy, associated with early metastasis, drug resistance and poor outcomes. We previously demonstrated a putative tumor suppressive role for concentrative nucleoside transporter 1 (CNT1) in PDAC. Here we demonstrate the regulator of G protein signaling (RGS) 11 as a key target of CNT1, with potent tumor suppressive properties in PDAC. Compared to normal human pancreas, RGS11 expression is diminished in human PDAC tissues which correspond with the reduced patient survival times. In addition, quasi-mesenchymal pancreatic tumor cell lines with accelerated growth, metastatic propensity, and innate resistance to nucleoside analogs showed relatively lower RGS11 expression than the epithelial counterparts. Interestingly, RGS11 levels reversibly modulated the epithelial-mesenchymal transition (EMT) of human PDAC cell lines influencing the chemotherapeutic sensitivities of anti-PDAC drugs. Additionally, stable lentiviral-mediated RGS11 expression reduced the cellular proliferation and colony establishment, increased the apoptotic index, and decreased the migratory and invasive abilities in quasi-mesenchymal tumor cell lines, whereas RGS11 depletion in epithelial tumor cell lines showed opposite effects. Global transcriptomic analysis revealed RGS11 replenishment in PDAC cells to suppress CD44-directed stemness features with significant reprogramming of the PDAC oncogenic landscape. Furthermore, RGS11 reduced the primary tumor burden and metastatic occurrence in a mouse model of PDAC. Together, these findings uncover RGS11 as a key target of CNT1 that exhibits therapeutic potential for intervention of aggressive PDAC. Implications: RGS11 identified as a downstream target of a gemcitabine transporter CNT1 exerts potent anti-tumorigenic features in pancreatic ductal adenocarcinoma with therapeutic and prognostic values.

Prostate cancer ranges from indolent to rapidly progressive. An elevated cell proliferation index portends poor outcomes, yet the molecular alterations essential for increased cell proliferation remain ill-defined. Gain of MYC combined with biallelic PTEN loss predicts prostate cancer mortality. Prior studies have shown that combined MYC overexpression and Pten loss, driven by the Hoxb13 locus, results in prostatic intraepithelial neoplastic (PIN) lesions that progress to metastatic disease (BMPC mice). Yet, single gene alterations in these mice result only in PIN. Herein, we performed transcriptomic profiling of PIN lesions from each of the 3 genotypes. While MYC alone resulted in increases in genes related to cell cycle regulation/cell division, combined MYC and Pten loss led to a further and more consistent increase, and a synergistic cell cycle progression. Increased ribosome biogenesis/translation are required for cell proliferation. While MYC alone increased 45S rRNA, and most components of the translation machinery, these were more strongly induced in BMPC mice. Surprisingly, Pten loss alone resulted in a downregulation of translation machinery genes, which could explain the absence of biallelic PTEN loss in human PIN and early carcinomas. Some MYC targets were increased only after Pten loss, indicating Pten loss increases MYC activity. Implications: These findings are that increased cell cycle and translational machinery gene induction may explain the synergy between MYC and PTEN loss for increasing prostate cancer cell proliferation and disease aggressiveness. Finally, these results provide further support for the therapeutic targeting of translation in prostate cancer.

Human glioblastoma (GBM) is a remarkable example of a highly aggressive and untreatable tumor. A formidable challenge in treating GBM is its extensive intratumor heterogeneity, which traditional bulk tissue analysis fails to capture. Fluorescence-guided multiple sampling, utilizing 5-aminolevulinic acid for tumor visualization, offers objective tumor tissue identification and enhanced spatial resolution. In this study, we present a perspective on a novel "spatial-in-spatial" approach that enables comprehensive analysis of tumor areas and their microenvironment-at macroscopic and microscopic levels-by combining fluorescence-guided multiple sampling with spatial-omics technologies. This perspective discusses how this integrated methodology has the potential to advance our understanding of GBM biology through the high-resolution, multidimensional characterization of tumor heterogeneity and identification of novel, area-specific therapeutic targets.

Histone citrullination is catalyzed by peptidyl-arginine deiminases (PAD) that play a role in gene regulation, and several specific inhibitors have been developed. However, the clinical significance, molecular mechanisms of histone citrullination and PADs, and effects of PAD inhibitors in pancreatic ductal adenocarcinoma (PDAC) remain unclear. This study aimed to investigate the role and potential molecular mechanisms of PADs in PDAC. Histone citrullination was upregulated and strongly associated with the nuclear expression of PAD2, one of the PAD family, in human PDAC tissues, correlating with aggressiveness and poor prognosis. PAD2 overexpression increased PDAC cell proliferation, whereas its knockdown had the opposite effect in vitro. PAD2 was recruited to the promoter regions of PRUNE1 and E2F1, resulting in the activation of their mRNA expression via increased histone citrullination and chromatin accessibility. PAD2 overexpression enhanced tumorigenicity and increased PRUNE1 expression and M2 tumor-associated macrophage (M2 TAM) infiltration in vivo. PAD2 inhibitor suppressed the growth and tumorigenicity of PAD2-expressing PDAC mouse models by reducing PRUNE1 expression and M2 macrophage infiltration. Pad2 knockdown and PAD inhibitor treatment showed similar effects in syngeneic mouse models. The triple-high expression of nuclear PAD2, PRUNE1, and the M2 TAM marker CD206 may serve as independent adverse prognostic factors for human PDAC. Conclusively, PAD2-mediated histone citrullination drives PDAC progression by epigenetically regulating downstream target genes and influencing the tumor microenvironment. The PAD2-PRUNE1-M2 TAM axis presents a promising therapeutic target and prognostic indicator for PDAC.

Implications: Elevated PAD2 expression promotes PDAC progression by epigenetically activating PRUNE1 and enhancing M2 macrophage polarization.

Integrin α5β1 and αv cross-talk in chemotaxis, and clonogenic survival of prostate cancer cells is abrogated by a bispecific α5β1/αv antibody (BsAbα5β1/αv), which uniquely induces internalization and lysosomal degradation of target integrins. We hypothesized that the BsAbα5β1/αv inactivates pathologic mechanosignaling pathways that correlate with integrin expression from patient samples. Mechanistic studies indicate that the BsAbα5β1/αv uniquely reverses Yes-associated protein, β-catenin, and focal adhesion kinase nuclear localization compared with monospecific integrin α5β1 and αv antibody controls in basal-type androgen receptor-negative prostate cancer cells. Dual integrin αv and α5 knockdown alone phenocopied the BsAbα5β1/αv effect. Following BsAbα5β1/αv treatment, Assay for Transposase-Accessible Chromatin using sequencing studies indicated the chromatin accessibility to TEAD and AP-1 family members was markedly reduced. In vitro and in vivo RNA sequencing indicated downregulation of Myc/E2F, TGF-β, and epithelial-mesenchymal transition and upregulation of type I and II IFN transcriptomic pathways. The BsAbα5β1/αv induced CXCL10 and CCL5 cytokine secretion, immune-infiltration of tumors, and NK cell-mediated elimination of the basal-type prostate cancer xenografts in nude mice. αv integrin was highly expressed and principally correlated with the Myc signaling pathway in rapid autopsy tissue microarrays, consistent with correlative data from the SU2C metastatic castration-resistant prostate cancer and Deutsches Krebsforschungszentrum early-onset prostate cancer cohorts. These studies connect integrin signaling with the central biology of basal-type and castration-resistant prostate cancers and define a novel therapeutic strategy that controls critical immunosuppressive pathways.

Implications: Dual integrin α5β1/αv targeting with a bispecific antibody represents a novel therapeutic strategy that reprograms the epigenetic and transcriptomic signatures of basal-type prostate cancer with induction of immunologic tumor control.

We identified a long noncoding RNA, LINC01235, with significant enrichment in luminal progenitor (LP)-like cells in triple-negative breast cancer (TNBC) organoids and cell lines. Antisense-mediated knockdown or genetic knockout of LINC01235 in TNBC cell lines led to a decline in cell proliferation and adversely affected the ability to form organoids. A comprehensive co-expression analysis, leveraging The Cancer Genome Atlas data, revealed a distinct correlation between LINC01235 expression and the expression of NFIB, a neighboring gene encoding a transcription factor. Subsequent CRISPR knockout or antisense oligonucleotide-mediated knockdown studies demonstrated an upstream regulatory role of LINC01235 over NFIB. Moreover, our investigations demonstrated that LINC01235 regulates the Notch pathway through NFIB, and chromatin isolation by RNA purification followed by qPCR results indicated the direct binding of LINC01235 to the NFIB promoter. Our findings demonstrate that LINC01235 positively regulates NFIB transcription, which in turn modulates the Notch pathway, influencing LP-like cell proliferation in breast cancer progression. This study highlights a pivotal role of LINC01235 in TNBC and its potential as a therapeutic target.

Implications: This study demonstrates the central role of LINC01235 as an upstream positive regulator of NFIB and the Notch signaling pathway to induce the production of LP-like cells in TNBC.

Myeloid-derived suppressor cells (MDSCs) are characterized by abnormal phenotypes, high heterogeneity, and immunosuppressive function. MDSCs are critical components in the tumor immune microenvironment, contributing to cancer progression by inhibiting T cells, B cells, NK cells, and dendritic cells while promoting regulatory T cells, tumor-associated macrophages, and Th17 cells. Beyond immunosuppression, MDSCs facilitate tumor angiogenesis, tumor cell stemness, epithelial-mesenchymal transition, and premetastatic niche formation. Current therapeutic strategies targeting MDSCs include depletion, functional inhibition, induction of differentiation, and disruption of MDSC recruitment and activation. Various therapeutic agents-including chemotherapeutics, mAbs, small-molecule inhibitors, and natural compounds-have shown efficacy in modulating MDSC activity. Combining MDSC-targeted therapy with existing immunotherapies, such as immune checkpoint inhibitors, may further improve antitumor responses.