Oncology
Abstract
Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Its pathogenesis is frequently linked to liver inflammation. Gain-of-function mutations in the gene encoding β-catenin are frequent genetic modifications found in human HCCs. Thus, we investigated whether inflammation was a component of β-catenin–induced tumorigenesis using genetically modified mouse models that recapitulated the stages of initiation and progression of this tumoral process. Oncogenic β-catenin signaling was found to induce an inflammatory program in hepatocytes that involved direct transcriptional control by β-catenin and activation of the NF-κB pathway. This led to a specific inflammatory response, the intensity of which determined the degree of tumor aggressiveness. The chemokine-like chemotactic factor leukocyte cell–derived chemotaxin 2 (LECT2) and invariant NKT (iNKT) cells were identified as key interconnected effectors of liver β-catenin–induced inflammation. In genetic deletion models lacking the gene encoding LECT2 or iNKT cells, hepatic β-catenin signaling triggered the formation of highly malignant HCCs with lung metastasis. Thus, our results identify inflammation as a key player in β-catenin–induced liver tumorigenesis. We provide strong evidence that, by activating pro- and antiinflammatory mediators, β-catenin signaling produces an inflammatory microenvironment that has an impact on tumoral development. Our data are consistent with the fact that most β-catenin–activated HCCs are of better prognosis.
Authors
Marie Anson, Anne-Marie Crain-Denoyelle, Véronique Baud, Fanny Chereau, Angélique Gougelet, Benoit Terris, Satoshi Yamagoe, Sabine Colnot, Mireille Viguier, Christine Perret, Jean-Pierre Couty
Abstract
Pancreatic cancer is almost invariably associated with mutations in the KRAS gene, most commonly KRASG12D, that result in a dominant-active form of the KRAS GTPase. However, how KRAS mutations promote pancreatic carcinogenesis is not fully understood, and whether oncogenic KRAS is required for the maintenance of pancreatic cancer has not been established. To address these questions, we generated two mouse models of pancreatic tumorigenesis: mice transgenic for inducible KrasG12D, which allows for inducible, pancreas-specific, and reversible expression of the oncogenic KrasG12D, with or without inactivation of one allele of the tumor suppressor gene p53. Here, we report that, early in tumorigenesis, induction of oncogenic KrasG12D reversibly altered normal epithelial differentiation following tissue damage, leading to precancerous lesions. Inactivation of KrasG12D in established precursor lesions and during progression to cancer led to regression of the lesions, indicating that KrasG12D was required for tumor cell survival. Strikingly, during all stages of carcinogenesis, KrasG12D upregulated Hedgehog signaling, inflammatory pathways, and several pathways known to mediate paracrine interactions between epithelial cells and their surrounding microenvironment, thus promoting formation and maintenance of the fibroinflammatory stroma that plays a pivotal role in pancreatic cancer. Our data establish that epithelial KrasG12D influences multiple cell types to drive pancreatic tumorigenesis and is essential for tumor maintenance. They also strongly support the notion that inhibiting KrasG12D, or its downstream effectors, could provide a new approach for the treatment of pancreatic cancer.
Authors
Meredith A. Collins, Filip Bednar, Yaqing Zhang, Jean-Christophe Brisset, Stefanie Galbán, Craig J. Galbán, Sabita Rakshit, Karen S. Flannagan, N. Volkan Adsay, Marina Pasca di Magliano
Abstract
The CBX7 gene encodes a polycomb group protein that is known to be downregulated in many types of human cancers, although the role of this protein in carcinogenesis remains unclear. To shed light on this issue, we generated mice null for Cbx7. Mouse embryonic fibroblasts derived from these mice had a higher growth rate and reduced susceptibility to senescence compared with their WT counterparts. This was associated with upregulated expression of multiple cell cycle components, including cyclin E, which is known to play a key role in lung carcinogenesis in humans. Adult Cbx7-KO mice developed liver and lung adenomas and carcinomas. In in vivo and in vitro experiments, we demonstrated that CBX7 bound to the CCNE1 promoter in a complex that included HDAC2 and negatively regulated CCNE1 expression. Finally, we found that the lack of CBX7 protein expression in human lung carcinomas correlated with CCNE1 overexpression. These data suggest that CBX7 is a tumor suppressor and that its loss plays a key role in the pathogenesis of cancer.
Authors
Floriana Forzati, Antonella Federico, Pierlorenzo Pallante, Adele Abbate, Francesco Esposito, Umberto Malapelle, Romina Sepe, Giuseppe Palma, Giancarlo Troncone, Marzia Scarfò, Claudio Arra, Monica Fedele, Alfredo Fusco
Abstract
Mutations in the gene encoding the p110α subunit of PI3K (PIK3CA) that result in enhanced PI3K activity are frequently observed in human cancers. To better understand the role of mutant PIK3CA in the initiation or progression of tumorigenesis, we generated mice in which a PIK3CA mutation commonly detected in human cancers (the H1047R mutation) could be conditionally knocked into the endogenous Pik3ca locus. Activation of this mutation in the mouse ovary revealed that alone, Pik3caH1047R induced premalignant hyperplasia of the ovarian surface epithelium but no tumors. Concomitantly, we analyzed several human ovarian cancers and found PIK3CA mutations coexistent with KRAS and/or PTEN mutations, raising the possibility that a secondary defect in a co-regulator of PI3K activity may be required for mutant PIK3CA to promote transformation. Consistent with this notion, we found that Pik3caH1047R mutation plus Pten deletion in the mouse ovary led to the development of ovarian serous adenocarcinomas and granulosa cell tumors. Both mutational events were required for early, robust Akt activation. Pharmacological inhibition of PI3K/mTOR in these mice delayed tumor growth and prolonged survival. These results demonstrate that the Pik3caH1047R mutation with loss of Pten is enough to promote ovarian cell transformation and that we have developed a model system for studying possible therapies.
Authors
Kathryn M. Kinross, Karen G. Montgomery, Margarete Kleinschmidt, Paul Waring, Ivan Ivetac, Anjali Tikoo, Mirette Saad, Lauren Hare, Vincent Roh, Theo Mantamadiotis, Karen E. Sheppard, Georgina L. Ryland, Ian G. Campbell, Kylie L. Gorringe, James G. Christensen, Carleen Cullinane, Rodney J. Hicks, Richard B. Pearson, Ricky W. Johnstone, Grant A. McArthur, Wayne A. Phillips
Abstract
Increased expression of the regulatory subunit of HIFs (HIF-1α or HIF-2α) is associated with metabolic adaptation, angiogenesis, and tumor progression. Understanding how HIFs are regulated is of intense interest. Intriguingly, the molecular mechanisms that link mitochondrial function with the HIF-regulated response to hypoxia remain to be unraveled. Here we describe what we believe to be novel functions of the human gene CHCHD4 in this context. We found that CHCHD4 encodes 2 alternatively spliced, differentially expressed isoforms (CHCHD4.1 and CHCHD4.2). CHCHD4.1 is identical to MIA40, the homolog of yeast Mia40, a key component of the mitochondrial disulfide relay system that regulates electron transfer to cytochrome c. Further analysis revealed that CHCHD4 proteins contain an evolutionarily conserved coiled-coil-helix-coiled-coil-helix (CHCH) domain important for mitochondrial localization. Modulation of CHCHD4 protein expression in tumor cells regulated cellular oxygen consumption rate and metabolism. Targeting CHCHD4 expression blocked HIF-1α induction and function in hypoxia and resulted in inhibition of tumor growth and angiogenesis in vivo. Overexpression of CHCHD4 proteins in tumor cells enhanced HIF-1α protein stabilization in hypoxic conditions, an effect insensitive to antioxidant treatment. In human cancers, increased CHCHD4 expression was found to correlate with the hypoxia gene expression signature, increasing tumor grade, and reduced patient survival. Thus, our study identifies a mitochondrial mechanism that is critical for regulating the hypoxic response in tumors.
Authors
Jun Yang, Oliver Staples, Luke W. Thomas, Thomas Briston, Mathew Robson, Evon Poon, Maria L. Simões, Ethaar El-Emir, Francesca M. Buffa, Afshan Ahmed, Nicholas P. Annear, Deepa Shukla, Barbara Pedley, Patrick H. Maxwell, Adrian L. Harris, Margaret Ashcroft
Abstract
Insulin like growth factor–1 (IGF-1) stimulates increased proliferation and survival of mammary epithelial cells and also promotes mammary tumorigenesis. To study the effects of IGF-1 on the mammary gland in vivo, we used BK5.IGF-1 transgenic (Tg) mice. In these mice, IGF-1 overexpression is controlled by the bovine keratin 5 promoter and recapitulates the paracrine exposure of breast epithelium to stromal IGF-1 that is seen in women. Studies have shown that BK5.IGF-1 Tg mice are more susceptible to mammary tumorigenesis than wild-type littermates. Investigation of the mechanisms underlying increased mammary cancer risk, reported here, revealed that IGF-1 preferentially activated the PI3K/Akt pathway in glands from prepubertal Tg mice, resulting in increased cyclin D1 expression and hyperplasia. However, in glands from postpubertal Tg mice, a pathway switch occurred and activation of the Ras/Raf/MAPK pathway predominated, without increased cyclin D1 expression or proliferation. We further showed that in prepubertal Tg glands, signaling was mediated by formation of an ERα/IRS-1 complex, which activated IRS-1 and directed signaling via the PI3K/Akt pathway. Conversely, in postpubertal Tg glands, reduced ERα expression failed to stimulate formation of the ERα/IRS-1 complex, allowing signaling to proceed via the alternate Ras/Raf/MAPK pathway. These in vivo data demonstrate that changes in ERα expression at different stages of development direct IGF-1 signaling and the resulting tissue responses. As ERα levels are elevated during the prepubertal and postmenopausal stages, these may represent windows of susceptibility during which increased IGF-1 exposure maximally enhances breast cancer risk.
Authors
Jie Tian, Thomas R. Berton, Stephanie H. Shirley, Isabel Lambertz, Irma B. Gimenez-Conti, John DiGiovanni, Kenneth S. Korach, Claudio J. Conti, Robin Fuchs-Young
Abstract
Rhabdomyosarcoma (RMS) is a malignancy of muscle myoblasts, which fail to exit the cell cycle, resist terminal differentiation, and are blocked from fusing into syncytial skeletal muscle. In some patients, RMS is caused by a translocation that generates the fusion oncoprotein PAX-FOXO1, but the underlying RMS pathogenetic mechanisms that impede differentiation and promote neoplastic transformation remain unclear. Using a Drosophila model of PAX-FOXO1–mediated transformation, we show here that mutation in the myoblast fusion gene rolling pebbles (rols) dominantly suppresses PAX-FOXO1 lethality. Further analysis indicated that PAX-FOXO1 expression caused upregulation of rols, which suggests that Rols acts downstream of PAX-FOXO1. In mammalian myoblasts, gene silencing of Tanc1, an ortholog of rols, revealed that it is essential for myoblast fusion, but is dispensable for terminal differentiation. Misexpression of PAX-FOXO1 in myoblasts upregulated Tanc1 and blocked differentiation, whereas subsequent reduction of Tanc1 expression to native levels by RNAi restored both fusion and differentiation. Furthermore, decreasing human TANC1 gene expression caused RMS cancer cells to lose their neoplastic state, undergo fusion, and form differentiated syncytial muscle. Taken together, these findings identify misregulated myoblast fusion caused by ectopic TANC1 expression as a RMS neoplasia mechanism and suggest fusion molecules as candidates for targeted RMS therapy.
Authors
Usha Avirneni-Vadlamudi, Kathleen A. Galindo, Tiana R. Endicott, Vera Paulson, Scott Cameron, Rene L. Galindo
Abstract
Glioblastoma multiforme (GBM) is the most common and lethal of all gliomas. The current standard of care includes surgery followed by concomitant radiation and chemotherapy with the DNA alkylating agent temozolomide (TMZ). O6-methylguanine–DNA methyltransferase (MGMT) repairs the most cytotoxic of lesions generated by TMZ, O6-methylguanine. Methylation of the MGMT promoter in GBM correlates with increased therapeutic sensitivity to alkylating agent therapy. However, several aspects of TMZ sensitivity are not explained by MGMT promoter methylation. Here, we investigated our hypothesis that the base excision repair enzyme alkylpurine–DNA–N-glycosylase (APNG), which repairs the cytotoxic lesions N3-methyladenine and N7-methylguanine, may contribute to TMZ resistance. Silencing of APNG in established and primary TMZ-resistant GBM cell lines endogenously expressing MGMT and APNG attenuated repair of TMZ-induced DNA damage and enhanced apoptosis. Reintroducing expression of APNG in TMZ-sensitive GBM lines conferred resistance to TMZ in vitro and in orthotopic xenograft mouse models. In addition, resistance was enhanced with coexpression of MGMT. Evaluation of APNG protein levels in several clinical datasets demonstrated that in patients, high nuclear APNG expression correlated with poorer overall survival compared with patients lacking APNG expression. Loss of APNG expression in a subset of patients was also associated with increased APNG promoter methylation. Collectively, our data demonstrate that APNG contributes to TMZ resistance in GBM and may be useful in the diagnosis and treatment of the disease.
Authors
Sameer Agnihotri, Aaron S. Gajadhar, Christian Ternamian, Thierry Gorlia, Kristin L. Diefes, Paul S. Mischel, Joanna Kelly, Gail McGown, Mary Thorncroft, Brett L. Carlson, Jann N. Sarkaria, Geoffrey P. Margison, Kenneth Aldape, Cynthia Hawkins, Monika Hegi, Abhijit Guha
Abstract
Constitutive activation of NF-κB is a frequent event in human cancers, playing important roles in cancer development and progression. In nontransformed cells, NF-κB activation is tightly controlled by IκBs. IκBs bind NF-κB in the cytoplasm, preventing it from translocating to the nucleus to modulate gene expression. Stimuli that activate NF-κB signaling trigger IκB degradation, enabling nuclear translocation of NF-κB. Among the genes regulated by NF-κB are those encoding the IκBs, providing a negative feedback loop that limits NF-κB activity. How transformed cells override this NF-κB/IκB negative feedback loop remains unclear. Here, we report in human glioma cell lines that microRNA-30e* (miR-30e*) directly targets the IκBα 3ι-UTR and suppresses IκBα expression. Overexpression of miR-30e* in human glioma cell lines led to hyperactivation of NF-κB and enhanced expression of NF-κB–regulated genes, which promoted glioma cell invasiveness in in vitro assays and in an orthotopic xenotransplantation model. These effects of miR-30e* were shown to be clinically relevant, as miR-30e* was found to be upregulated in primary human glioma cells and correlated with malignant progression and poor survival. Hence, miR-30e* provides an epigenetic mechanism that disrupts the NF-κB/IκBα loop and may represent a new therapeutic target and prognostic marker.
Authors
Lili Jiang, Chuyong Lin, Libing Song, Jueheng Wu, Baixue Chen, Zhe Ying, Lishan Fang, Xiao Yan, Mian He, Jun Li, Mengfeng Li
Abstract
Advanced human thyroid cancers, particularly those that are refractory to treatment with radioiodine (RAI), have a high prevalence of BRAF (v-raf murine sarcoma viral oncogene homolog B1) mutations. However, the degree to which these cancers are dependent on BRAF expression is still unclear. To address this question, we generated mice expressing one of the most commonly detected BRAF mutations in human papillary thyroid carcinomas (BRAFV600E) in thyroid follicular cells in a doxycycline-inducible (dox-inducible) manner. Upon dox induction of BRAFV600E, the mice developed highly penetrant and poorly differentiated thyroid tumors. Discontinuation of dox extinguished BRAFV600E expression and reestablished thyroid follicular architecture and normal thyroid histology. Switching on BRAFV600E rapidly induced hypothyroidism and virtually abolished thyroid-specific gene expression and RAI incorporation, all of which were restored to near basal levels upon discontinuation of dox. Treatment of mice with these cancers with small molecule inhibitors of either MEK or mutant BRAF reduced their proliferative index and partially restored thyroid-specific gene expression. Strikingly, treatment with the MAPK pathway inhibitors rendered the tumor cells susceptible to a therapeutic dose of RAI. Our data show that thyroid tumors carrying BRAFV600E mutations are exquisitely dependent on the oncoprotein for viability and that genetic or pharmacological inhibition of its expression or activity is associated with tumor regression and restoration of RAI uptake in vivo in mice. These findings have potentially significant clinical ramifications.
Authors
Debyani Chakravarty, Elmer Santos, Mabel Ryder, Jeffrey A. Knauf, Xiao-Hui Liao, Brian L. West, Gideon Bollag, Richard Kolesnick, Tin Htwe Thin, Neal Rosen, Pat Zanzonico, Steven M. Larson, Samuel Refetoff, Ronald Ghossein, James A. Fagin
Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)