Earliest Metabolic Changes Associated with the Initiation of Pancreatic Cancer.

Pancreatic cancer is usually detected at a late stage, when tumors have already metastasized; therefore, it has a poor prognosis with a 5-year survival rate of 11% to 12%. A key to targeting this high mortality is to develop methods for detecting the disease at a stage in which it is still local to the pancreas. However, this needs a better understanding of the events that govern pancreatic cancer oncogenesis. In this issue of Cancer Research, Neuß and colleagues report metabolic changes associated with acinar-to-ductal metaplasia (ADM), an initiating event that leads to the formation of precursor lesions for pancreatic ductal adenocarcinoma (PDAC). Their findings reveal a switch to aerobic glycolysis, increased c-MYC signaling, and increased serine metabolism as driving factors for the ADM process. These findings are important as they demonstrate that metabolic changes that drive the proliferation and metastasis of full-blown PDAC begin in the earliest lesions. The data not only provide insights into how PDAC develops but also a potential explanation for previously described findings, such as circulating lesion cells can be detected even when no carcinoma in situ is present. In summary, this article is highly relevant for furthering our understanding of how metabolic reprogramming drives the earliest events leading to PDAC development and could lay the groundwork for developing methods for early detection or intervention. See related article by Neuß et al., p. 2297.

CDC7 inhibition impairs neuroendocrine transformation in lung and prostate tumors through MYC degradation.

Neuroendocrine (NE) transformation is a mechanism of resistance to targeted therapy in lung and prostate adenocarcinomas leading to poor prognosis. Up to date, even if patients at high risk of transformation can be identified by the occurrence of Tumor Protein P53 (TP53) and Retinoblastoma Transcriptional Corepressor 1 (RB1) mutations in their tumors, no therapeutic strategies are available to prevent or delay histological transformation. Upregulation of the cell cycle kinase Cell Division Cycle 7 (CDC7) occurred in tumors during the initial steps of NE transformation, already after TP53/RB1 co-inactivation, leading to induced sensitivity to the CDC7 inhibitor simurosertib. CDC7 inhibition suppressed NE transdifferentiation and extended response to targeted therapy in in vivo models of NE transformation by inducing the proteasome-mediated degradation of the MYC Proto-Oncogen (MYC), implicated in stemness and histological transformation. Ectopic overexpression of a degradation-resistant MYC isoform reestablished the NE transformation phenotype observed on targeted therapy, even in the presence of simurosertib. CDC7 inhibition also markedly extended response to standard cytotoxics (cisplatin, irinotecan) in lung and prostate small cell carcinoma models. These results nominate CDC7 inhibition as a therapeutic strategy to constrain lineage plasticity, as well as to effectively treat NE tumors de novo or after transformation. As simurosertib clinical efficacy trials are ongoing, this concept could be readily translated for patients at risk of transformation.

MGA deletion leads to Richter's transformation by modulating mitochondrial OXPHOS.

Richter's transformation (RT) is a progression of chronic lymphocytic leukemia (CLL) to aggressive lymphoma. MGA (Max gene associated), a functional MYC suppressor, is mutated at 3% in CLL and 36% in RT. However, genetic models and molecular mechanisms of MGA deletion that drive CLL to RT remain elusive. We established an RT mouse model by knockout of Mga in the Sf3b1/Mdr CLL model using CRISPR-Cas9 to determine the role of Mga in RT. Murine RT cells exhibited mitochondrial aberrations with elevated oxidative phosphorylation (OXPHOS). Through RNA sequencing and functional characterization, we identified Nme1 (nucleoside diphosphate kinase) as an Mga target, which drives RT by modulating OXPHOS. Given that NME1 is also a known MYC target without targetable compounds, we found that concurrent inhibition of MYC and electron transport chain complex II substantially prolongs the survival of RT mice in vivo. Our results suggest that the Mga-Nme1 axis drives murine CLL-to-RT transition via modulating OXPHOS, highlighting a potential therapeutic avenue for RT.

Biomarkers of epithelial-mesenchymal transition: E-cadherin and beta-catenin in malignant transformation of oral lesions.

Objective: Detecting oral lesions at high risk of becoming cancer may enable early interventions to prevent oral cancer. The diagnosis of dysplasia in an oral lesion is used to predict this risk but is subject to interobserver and intraobserver variability. Studying biomarkers or molecular markers that reflect underlying molecular alterations can serve as an additional and objective method of risk assessment. E-cadherin and beta-catenin, molecular markers of epithelial-mesenchymal transition (EMT), potentially contribute to early malignant progression in oral tissue. This narrative review provides an overview of EMT, its relation to oral cancer, and the interaction among E-cadherin, beta-catenin, and the Wnt pathway in malignant progression of oral tissue. Methods: Full-text literature on EMT, E-cadherin, beta-catenin, oral epithelial dysplasia, and oral cancer was retrieved from PubMed and Google Scholar. Results: Sixty original research articles, reviews, and consensus statements were selected for review. Discussion: EMT, a biological mechanism characterized by epithelial and mesenchymal changes, can contribute to cancer development. Molecular markers of EMT including TWIST, vimentin, and N-cadherin may serve as prognostic markers of oral cancer. Dependent on Wnt pathway activity and the loss of membranous E-cadherin, E-cadherin and beta-catenin can play various roles along the spectrum of malignant progression, including tumour inhibition, early tumour progression, and late-stage tumour progression. Cross-sectional immunohistochemical research has found changes in expression patterns of E-cadherin and beta-catenin from normal oral tissue, oral epithelial dysplasia, to oral squamous cell carcinoma. Conclusion: Future research should explore the longitudinal role of EMT markers in predicting malignant progression in oral tissue.

Objectif: La détection de lésions buccales présentant un risque élevé d'évoluer en cancer peut permettre des interventions précoces pour prévenir le cancer de la bouche. Le diagnostic de dysplasie dans le cas de lésions buccales sert à prédire ce risque, mais il est soumis à une variabilité d'un observateur à l'autre et avec le même observateur. L'étude de marqueurs biologiques ou de marqueurs moléculaires correspondant à des altérations moléculaires sous-jacentes peut constituer une méthode objective supplémentaire d'évaluation des risques. L'E-cadhérine et la bêta-caténine, des marqueurs moléculaires de la transition épithélio-mésenchymateuse (TEM), pourraient contribuer aux premières étapes de l'évolution maligne du tissu buccal. Cette revue narrative donne un aperçu de la TEM, de ses liens avec le cancer de la bouche et de l'interaction entre l'E-cadhérine, la bêta-caténine et la voie de signalisation Wnt dans l'évolution maligne du tissu buccal. Méthodes: On a obtenu le texte intégral d'études portant sur la TEM, l'E-cadhérine, la bêta-caténine, la dysplasie épithéliale buccale et le cancer de la bouche sur PubMed et Google Scholar. Résultats: Soixante articles sur des études originales, des revues et des déclarations de consensus ont été sélectionnés aux fins d'examen. Discussion: La TEM, un mécanisme biologique caractérisé par des changements épithéliaux et mésenchymateux, peut contribuer à l'apparition d'un cancer. Les marqueurs moléculaires de la TEM, notamment TWIST, la vimentine et la N-cadhérine, peuvent servir de marqueurs pronostiques du cancer de la bouche. En fonction de l'activité de la voie de signalisation Wnt et de la perte de l'E-cadhérine membraneuse, l'E-cadhérine et la bêta-caténine peuvent jouer divers rôles dans le spectre de l'évolution maligne, notamment l'inhibition tumorale, la progression tumorale précoce et l'évolution tumorale avancée. Des études transversales d'immunohistochimie ont révélé des changements dans les modèles d'expression de l'E-cadhérine et de la bêta-caténine avec le passage du tissu buccal normal, de la dysplasie épithéliale buccale au carcinome squameux de la bouche. Conclusion: À l'avenir, des études devraient explorer le rôle longitudinal des marqueurs de la TEM dans la prévision de l'évolution maligne dans les tissus buccaux.

SOCS1 and SOCS3 as key checkpoint molecules in the immune responses associated to skin inflammation and malignant transformation.

SOCS are a family of negative inhibitors of the molecular cascades induced by cytokines, growth factors and hormones. At molecular level, SOCS proteins inhibit the kinase activity of specific sets of receptor-associated Janus Activated Kinases (JAKs), thereby suppressing the propagation of intracellular signals. Of the eight known members, SOCS1 and SOCS3 inhibit activity of JAKs mainly induced by cytokines and can play key roles in regulation of inflammatory and immune responses. SOCS1 and SOCS3 are the most well-characterized SOCS members in skin inflammatory diseases, where their inhibitory activity on cytokine activated JAKs and consequent anti-inflammatory action has been widely investigated in epidermal keratinocytes. Structurally, SOCS1 and SOCS3 share the presence of a N-terminal domain containing a kinase inhibitory region (KIR) motif able to act as a pseudo-substrate for JAK and to inhibit its activity. During the last decades, the design and employment of SOCS1 and SOCS3-derived peptides mimicking KIR domains in experimental models of dermatoses definitively established a strong anti-inflammatory and ameliorative impact of JAK inhibition on skin inflammatory responses. Herein, we discuss the importance of the findings collected in the past on SOCS1 and SOCS3 function in the inflammatory responses associated to skin immune-mediated diseases and malignancies, for the development of the JAK inhibitor drugs. Among them, different JAK inhibitors have been introduced in the clinical practice for treatment of atopic dermatitis and psoriasis, and others are being investigated for skin diseases like alopecia areata and vitiligo.

Caspase-3 promotes oncogene-induced malignant transformation via EndoG-dependent Src-STAT3 phosphorylation.

Accumulating evidence suggests that caspase-3 plays critical roles beyond apoptosis, serving pro-survival functions in malignant transformation and tumorigenesis. However, the mechanism of non-apoptotic action of caspase-3 in oncogenic transformation remains unclear. In the present study, we show that caspase-3 is consistently activated in malignant transformation induced by exogenous expression of oncogenic cocktail (c-Myc, p53DD, Oct-4, and H-Ras) in vitro as well as in the mouse mammary tumor virus-polyomavirus middle T antigen (MMTV-PyMT) mouse model of breast cancer. Genetic ablation of caspase-3 significantly attenuated oncogene-induced transformation of mammalian cells and delayed breast cancer progression in MMTV-PyMT transgenic mice. Mechanistically, active caspase-3 triggers the translocation of endonuclease G (EndoG) from mitochondria, which migrates to the nucleus, thereby induces phosphorylation of Src-STAT3 signaling pathway to facilitate oncogenic transformation. Taken together, our data suggest that caspase-3 plays pivotal role in facilitating rather than suppressing oncogene-induced malignant transformation of mammalian cells.

Atypical cell cycle regulation promotes mammary stem cell expansion during mammary development and tumourigenesis.

BACKGROUND: The cell cycle of mammary stem cells must be tightly regulated to ensure normal homeostasis of the mammary gland to prevent abnormal proliferation and susceptibility to tumorigenesis. The atypical cell cycle regulator, Spy1 can override cell cycle checkpoints, including those activated by the tumour suppressor p53 which mediates mammary stem cell homeostasis. Spy1 has also been shown to promote expansion of select stem cell populations in other developmental systems. Spy1 protein is elevated during proliferative stages of mammary gland development, is found at higher levels in human breast cancers, and promotes susceptibility to mammary tumourigenesis when combined with loss of p53. We hypothesized that Spy1 cooperates with loss of p53 to increase susceptibility to tumour initiation due to changes in susceptible mammary stem cell populations during development and drives the formation of more aggressive stem like tumours. METHODS: Using a transgenic mouse model driving expression of Spy1 within the mammary gland, mammary development and stemness were assessed. These mice were intercrossed with p53 null mice to study the tumourigenic properties of Spy1 driven p53 null tumours, as well as global changes in signaling via RNA sequencing analysis. RESULTS: We show that elevated levels of Spy1 leads to expansion of mammary stem cells, even in the presence of p53, and an increase in mammary tumour formation. Spy1-driven tumours have an increased cancer stem cell population, decreased checkpoint signaling, and demonstrate an increase in therapy resistance. Loss of Spy1 decreases tumor onset and reduces the cancer stem cell population. CONCLUSIONS: This data demonstrates the potential of Spy1 to expand mammary stem cell populations and contribute to the initiation and progression of aggressive, breast cancers with increased cancer stem cell populations.

Enhancer engagement sustains oncogenic transformation and progression of B-cell precursor acute lymphoblastic leukemia.

BACKGROUND: Enhancer reprogramming plays a significant role in the heterogeneity of cancer. However, we have limited knowledge about the impact of chromatin remodeling in B-Cell Precursor Acute Lymphoblastic Leukemia (BCP-ALL) patients, and how it affects tumorigenesis and drug response. Our research focuses on investigating the role of enhancers in sustaining oncogenic transformation in children with BCP-ALL. METHODS: We used ATAC-seq to study the accessibility of chromatin in pediatric BCP-ALL at three different stages-onset, remission, and relapse. Using a combination of computational and experimental methods, we were able to analyze the accessibility landscape and focus on the most significant cis-regulatory sites. These sites were then functionally validated through the use of Promoter capture Hi-C in a primary cell line model called LAL-B, followed by RNA-seq and genomic deletion of target sites using CRISPR-Cas9 editing. RESULTS: We found that enhancer activity changes during cancer progression and is mediated by the production of enhancer RNAs (eRNAs). CRISPR-Cas9-mediated validation of previously unknown eRNA productive enhancers demonstrated their capability to control the oncogenic activities of the MYB and DCTD genes. CONCLUSIONS: Our findings directly support the notion that productive enhancer engagement is a crucial determinant of the BCP-ALL and highlight the potential of enhancers as therapeutic targets in pediatric BCP-ALL.

Mitochondria-targeted catalase induced cell malignant transformation by the downregulation of p53 protein stability via USP28/miR-200b/PP2A-Cα axis.

Antioxidants exert a paradoxical influence on cancer prevention. The latest explanation for this paradox is the different target sites of antioxidants. However, it remains unclear how mitochondria-targeted antioxidants trigger specific p53-dependent pathways in malignant transformation models. Our study revealed that overexpression of mitochondria-targeted catalase (mCAT) instigated such malignant transformation via mouse double minute 2 homolog (MDM2) -mediated p53 degradation. In mouse epithelial JB6 Cl41 cells, the stable expression of mCAT resulted in MDM2-mediated p53 degradation, unlike in catalase-overexpressed Cl41 cells. Further, we demonstrated that mCAT overexpression upregulated ubiquitin-specific protease 28 (USP28) expression, which in turn stabilized c-Jun protein levels. This alteration initiated the activation of the miR-200b promoter transcription activity and a subsequent increase in miR-200b expression. Furthermore, elevated miR-200b levels then promoted its binding to the 3'-untranslated region of protein phosphatase 2A catalytic subunit (PP2A-C) α-isoform mRNA, consequently resulting in PP2A-C protein downregulation. This cascade of events ultimately contributed to increased MDM2 phosphorylation and p53 protein degradation. Thus, the mCAT overexpression triggers MDM2/p53-dependent malignant transformation through USP28/miR-200b/PP2A-Cα pathway, which may provide a new information for understanding mitochondria-targeted antioxidants facilitate the progression to the tumorigenic state.

NUP98-BPTF promotes oncogenic transformation through PIM1 upregulation.

INTRODUCTION: Nucleoporin 98 (NUP98) fusion proteins are recurrently found in leukemia and are associated with unfavorable clinical outcomes. They are distributed to the nucleus and contribute to leukemogenesis via aberrant transcriptional regulation. We previously identified NUP98-BPTF (NB) fusion in patients with T-cell acute lymphoblastic leukemia (T-ALL) using next-generation sequencing. The FG-repeat of NUP98 and the PHD finger and bromodomain of bromodomain PHD finger transcription factor (BPTF) are retained in the fusion. Like other NUP98 fusion proteins, NB is considered to regulate genes that are essential for leukemogenesis. However, its target genes or pathways remain unknown. MATERIALS AND METHODS: To investigate the potential oncogenic properties of the NB fusion protein, we lentivirally transduced a doxycycline-inducible NB expression vector into mouse NIH3T3 fibroblasts and human Jurkat T-ALL cells. RESULTS: NB promoted the transformation of mouse NIH3T3 fibroblasts by upregulating the proto-oncogene Pim1, which encodes a serine/threonine kinase. NB transcriptionally regulated Pim1 expression by binding to its promoter and activated MYC and mTORC1 signaling. PIM1 knockdown or pharmacological inhibition of mTORC1 signaling suppressed NB-induced NIH3T3 cell transformation. Furthermore, NB enhanced the survival of human Jurkat T-ALL cells by inactivating the pro-apoptotic protein BCL2-associated agonist of cell death (BAD). CONCLUSION: We demonstrated the pivotal role of NB in cell transformation and survival and identified PIM1as a key downstream target of NB. These findings propose a promising therapeutic strategy for patients with NB fusion-positive leukemia.

Melatonin Inhibits Chemical Carcinogen-mediated Malignant Transformation of Urothelial Cells: In Vitro Evidence.

BACKGROUND/AIM: The efficacy of melatonin and its biological significance in human bladder cancer remain poorly understood. This study aimed to investigate the functional role of melatonin in urothelial carcinogenesis. MATERIALS AND METHODS: In human normal urothelial SVHUC cells with exposure to the chemical carcinogen 3-methylcholanthrene, we assessed the effects of melatonin on the neoplastic/malignant transformation. RESULTS: In the in vitro system with carcinogen challenge, melatonin significantly prevented the neoplastic transformation of SV-HUC-1 cells. In addition, melatonin treatment resulted in increased expression of SIRT1, Rb1, and E-cadherin, and decreased expression of N-cadherin and FGFR3 in SV-HUC-1 cells. Furthermore, publicly available datasets from GSE3167 revealed that the expression of melatonin receptor 1 and melatonin receptor 2 was significantly down-regulated in bladder urothelial carcinoma tissues, compared with adjacent normal urothelial tissues. CONCLUSION: These findings indicate that melatonin serves as a suppressor for urothelial tumorigenesis. To the best of our knowledge, this is the first preclinical study demonstrating the impact of melatonin on the development of urothelial cancer.

Alpha-6 integrin deletion delays the formation of Brca1/p53-deficient basal-like breast tumors by restricting luminal progenitor cell expansion.

BACKGROUND: The aberrant amplification of mammary luminal progenitors is at the origin of basal-like breast cancers associated with BRCA1 mutations. Integrins mediate cell-matrix adhesion and transmit mechanical and chemical signals that drive epithelial stem cell functions and regulate tumor progression, metastatic reactivation, and resistance to targeted therapies. Consistently, we have recently shown that laminin-binding integrins are essential for the expansion and differentiation of mammary luminal progenitors in physiological conditions. As over-expression of the laminin-binding α6 integrin (Itgα6) is associated with poor prognosis and reduced survival in breast cancer, we here investigate the role of Itgα6 in mammary tumorigenesis. METHODS: We used Blg-Cre; Brca1F/F; Trp53F/F mice, a model that phenocopies human basal-like breast cancer with BRCA1 mutations. We generated mutant mice proficient or deficient in Itgα6 expression and followed tumor formation. Mammary tumors and pretumoral tissues were characterized by immunohistochemistry, flow cytometry, RT-qPCR, Western blotting and organoid cultures. Clonogenicity of luminal progenitors from preneoplastic glands was studied in 3D Matrigel cultures. RESULTS: We show that Itga6 deletion favors activation of p16 cell cycle inhibitor in the preneoplastic tissue. Subsequently, the amplification of luminal progenitors, the cell of origin of Brca1-deficient tumors, is restrained in Itgα6-deficient gland. In addition, the partial EMT program operating in Brca1/p53-deficient epithelium is attenuated in the absence of Itgα6. As a consequence of these events, mammary tumor formation is delayed in Itgα6-deficient mice. After tumor formation, the lack of Itgα6 does not affect tumor growth but rather alters their differentiation, resulting in reduced expression of basal cell markers. CONCLUSIONS: Our data indicate that Itgα6 has a pro-tumorigenic role in Blg-Cre; Brca1F/F; Trp53F/F mice developing basal-like mammary tumors. In particular, we reveal that Itgα6 is required for the luminal progenitor expansion and the aberrant partial EMT program that precedes the formation of BRCA1 deficient tumors.

Epithelial-mesenchymal transition associated markers in sarcomatoid transformation of clear cell renal cell carcinoma.

Epithelial-mesenchymal transition (EMT) plays a pivotal role in the development and progression of many cancers. Partial EMT (pEMT) could represent a critical step in tumor migration and dissemination. Sarcomatoid renal cell carcinoma (sRCC) is an aggressive form of renal cell carcinoma (RCC) composed of a carcinomatous (sRCC-Ca) and sarcomatous (sRCC-Sa) component. The role of (p)EMT in the progression of RCC to sRCC remains unclear. The aim of this study was to investigate the involvement of (p)EMT in RCC and sRCC. Tissue samples from 10 patients with clear cell RCC (ccRCC) and 10 patients with sRCC were selected. The expression of main EMT markers (miR-200 family, miR-205, SNAI1/2, TWIST1/2, ZEB1/2, CDH1/2, VIM) was analyzed by qPCR in ccRCC, sRCC-Ca, and sRCC-Sa and compared to non-neoplastic tissue and between both groups. Expression of E-cadherin, N-cadherin, vimentin and ZEB2 was analyzed using immunohistochemistry. miR-200c was downregulated in sRCC-Ca compared to ccRCC, while miR-200a was downregulated in sRCC-Sa compared to ccRCC. CDH1 was downregulated in sRCC-Sa when compared to any other group. ZEB2 was downregulated in ccRCC and sRCC compared to corresponding non-neoplastic kidney. A positive correlation was observed between CDH1 expression and miR-200a/b/c. Our results suggest that full EMT is not present in sRCC. Instead, discreet molecular differences exist between ccRCC, sRCC-Ca, and sRCC-Sa, possibly representing distinct intermediary states undergoing pEMT.

Assessment of TP53 and CDKN2A status as predictive markers of malignant transformation of sinonasal inverted papilloma.

The mechanism and predictive biomarkers of sinonasal inverted papilloma (IP) transformation into squamous cell carcinoma (SCC) are still unclear. We investigated the genetic mutations involved and the predictive biomarkers. Fourteen patients with SCC arising from IP and six patients with IPs without malignant transformation (sIP) were included. DNA was extracted separately from areas of normal tissue, IP, dysplasia, and SCC. Whole exome sequencing and immunohistochemistry was performed. Major oncogenic mutations were observed in the progression from IP to SCC. The most frequently mutated genes were TP53 (39%) and CDKN2A (27%). Mutations in TP53 and/or CDKN2A were observed in three of six IPs with malignant transformation (cIP); none were observed in sIPs. Tumor mutational burden (TMB) increased from IP to SCC (0.64/Mb, 1.11/Mb, and 1.25 for IP, dysplasia, and SCC, respectively). TMB was higher in the cIPs than in the sIPs (0.64/Mb vs 0.3/Mb). Three cIPs showed a diffuse strong or null pattern in p53, and one showed a total loss of p16, a distinct pattern from sIPs. Our result suggests that TP53 and CDKN2A status can be predictive markers of malignant transformation of IP. Furthermore, immunohistochemistry of p53 and p16 expression can be surrogate markers for TP53 and CDKN2A status.

Identification of Ppy-lineage cells as a novel origin of pancreatic ductal adenocarcinoma.

The Ppy gene encodes pancreatic polypeptide (PP) secreted by PP- or γ-cells, which are a subtype of endocrine cells localised mainly in the islet periphery. For a detailed characterisation of PP cells, we aimed to establish PP cell lines. To this end, we generated a mouse model harbouring the SV40 large T antigen (TAg) in the Rosa26 locus, which is expressed upon Ppy-promoter-mediated Cre-loxP recombination. Whereas Insulin1-CreERT-mediated TAg expression in beta cells resulted in insulinoma, surprisingly, Ppy-Cre-mediated TAg expression resulted in the malignant transformation of Ppy-lineage cells. These mice showed distorted islet structural integrity at 5 days of age compared with normal islets. CK19+ duct-like lesions contiguous with the islets were observed at 2 weeks of age, and mice developed aggressive pancreatic ductal adenocarcinoma (PDAC) at 4 weeks of age, suggesting that PDAC can originate from the islet/endocrine pancreas. This was unexpected as PDAC is believed to originate from the exocrine pancreas. RNA-sequencing analysis of Ppy-lineage islet cells from 7-day-old TAg+ mice showed a downregulation and an upregulation of endocrine and exocrine genes, respectively, in addition to the upregulation of genes and pathways associated with PDAC. These results suggest that the expression of an oncogene in Ppy-lineage cells induces a switch from endocrine cell fate to PDAC. Our findings demonstrate that Ppy-lineage cells may be an origin of PDAC and may provide novel insights into the pathogenesis of pancreatic cancer, as well as possible therapeutic strategies. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

The E3 ubiquitin ligase TRIP12 is required for pancreatic acinar cell plasticity and pancreatic carcinogenesis.

The E3 ubiquitin ligase thyroid hormone receptor interacting protein 12 (TRIP12) has been implicated in pancreatic adenocarcinoma (PDAC) through its role in mediating the degradation of pancreas transcription factor 1a (PTF1a). PTF1a is a transcription factor essential for the acinar differentiation state that is notably diminished during the early steps of pancreatic carcinogenesis. Despite these findings, the direct involvement of TRIP12 in the onset of pancreatic cancer has yet to be established. In this study, we demonstrated that TRIP12 protein was significantly upregulated in human pancreatic preneoplastic lesions. Furthermore, we observed that TRIP12 overexpression varied within PDAC samples and PDAC-derived cell lines. We further demonstrated that TRIP12 was required for PDAC-derived cell growth and for the expression of E2F-targeted genes. Acinar-to-ductal cell metaplasia (ADM) is a reversible process that reflects the high plasticity of acinar cells. ADM becomes irreversible in the presence of oncogenic Kras mutations and leads to the formation of preneoplastic lesions. Using two genetically modified mouse models, we showed that a loss of TRIP12 prevented acini from developing ADM in response to pancreatic injury. With two additional mouse models, we further discovered that a depletion of TRIP12 prevented the formation of KrasG12D-induced preneoplastic lesions and impaired metastasis formation in the presence of mutated KrasG12D and Trp53R172H genes. In summary our study identified an overexpression of TRIP12 from the early stages of pancreatic carcinogenesis and proposed this E3 ubiquitin ligase as a novel regulator of acinar plasticity with an important dual role in initiation and metastatic steps of PDAC. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Tumor initiation and early tumorigenesis: molecular mechanisms and interventional targets.

Tumorigenesis is a multistep process, with oncogenic mutations in a normal cell conferring clonal advantage as the initial event. However, despite pervasive somatic mutations and clonal expansion in normal tissues, their transformation into cancer remains a rare event, indicating the presence of additional driver events for progression to an irreversible, highly heterogeneous, and invasive lesion. Recently, researchers are emphasizing the mechanisms of environmental tumor risk factors and epigenetic alterations that are profoundly influencing early clonal expansion and malignant evolution, independently of inducing mutations. Additionally, clonal evolution in tumorigenesis reflects a multifaceted interplay between cell-intrinsic identities and various cell-extrinsic factors that exert selective pressures to either restrain uncontrolled proliferation or allow specific clones to progress into tumors. However, the mechanisms by which driver events induce both intrinsic cellular competency and remodel environmental stress to facilitate malignant transformation are not fully understood. In this review, we summarize the genetic, epigenetic, and external driver events, and their effects on the co-evolution of the transformed cells and their ecosystem during tumor initiation and early malignant evolution. A deeper understanding of the earliest molecular events holds promise for translational applications, predicting individuals at high-risk of tumor and developing strategies to intercept malignant transformation.

Molecular Prospective on Malignant Transformation of Mesenchymal Stem Cells: An Issue in Cell Therapy.

Mesenchymal stem cell (MSCs) therapy, as a rapidly developing area of medicine, holds great promise for the treatment of a variety of medical conditions. MSCs are multipotent stem cells that can be isolated from various tissues and could self-renew and differentiate. They secrete cytokines and trophic factors that create a regenerative microenvironment and have immunomodulatory properties. Although clinical trials have been conducted with MSCs in various diseases, concerns regarding the possibility of malignant transformation of these cells have been raised. The studies showed a higher rate of hematological malignancy and carcinogenesis in experimental models after MSC transplantation. The mechanisms underlying malignant transformation of MSCs are complex and not fully understood, but they are believed to involve the presence of special signaling molecules and alterations in cell behavior regulation pathways. Possible pathways that lead to MSCs' oncogenic transformation occur through two mechanisms: spontaneous and stimulated malignant transformation, including cell fusion, fusion proteins, and the tumor microenvironment. MSC-based therapies have the potential to revolutionize medicine, and addressing the issue of malignancy is crucial to ensure their safety and efficacy. Therefore, the purpose of the present review is to summarize the potential mechanisms of the malignant transformation of MSCs. [Figure: see text].

p53/MDM2 signaling pathway in aging, senescence and tumorigenesis.

A wealth of evidence has emerged that there is an association between aging, senescence and tumorigenesis. Senescence, a biological process by which cells cease to divide and enter a status of permanent cell cycle arrest, contributes to aging and aging-related diseases, including cancer. Aging populations have the higher incidence of cancer due to a lifetime of exposure to cancer-causing agents, reduction of repairing DNA damage, accumulated genetic mutations, and decreased immune system efficiency. Cancer patients undergoing cytotoxic therapies, such as chemotherapy and radiotherapy, accelerate aging. There is growing evidence that p53/MDM2 (murine double minute 2) axis is critically involved in regulation of aging, senescence and oncogenesis. Therefore, in this review, we describe the functions and mechanisms of p53/MDM2-mediated senescence, aging and carcinogenesis. Moreover, we highlight the small molecular inhibitors, natural compounds and PROTACs (proteolysis targeting chimeras) that target p53/MDM2 pathway to influence aging and cancer. Modification of p53/MDM2 could be a potential strategy for treatment of aging, senescence and tumorigenesis.