Disease Models & Mechanisms

KNTC1 introduces segmental heterogeneity to mitochondria

ABSTRACT Mitochondria contribute to cellular metabolism by providing a specialised milieu for energising cells by incorporating and processing the metabolites. However, heterogeneity between mitochondria has only partially been elucidated. Mitochondria dynamically alter their morphology and function during the life of an animal, when cells proliferate and grow. We here show that Kntc1, a highly evolutionarily conserved protein, translocates from the Golgi apparatus to linear mitochondrial segments (LMSs) upon glutamine deprivation and plays an essential role in maintaining LMSs. The LMSs to which Kntc1 localised exhibited an increase in the mitochondrial membrane potential, suggesting the role of Kntc1 in functioning as a reservoir for the energy-generating potential. Suppression of Kntc1 led to glutamine consumption and lactate production, thus impacting cellular metabolism, eventually leading to anchorage-independent growth of cells. Indeed, a KNTC1 variant was identified in a patient with ovarian cancer, suggesting that segmental regulation of the mitochondrial function is essential for maintaining tissue integrity.

Extended passaging of the SKOV3 ovarian cancer cell line leads to two phenotypically different strains

ABSTRACT Continuous passaging of cancer cell lines can drive phenotypic and genotypic divergence, potentially compromising the reliability of such models. In this study, we show that two late-passage strains (S1 and S2) of ovarian cancer cell line SKOV3, although authenticated via short tandem repeat (STR) profiling as identical, exhibit substantial differences in morphology, transcriptomic signatures, ability to form 3D cultures and chemotherapeutic responses. Notably, S1 formed compact 3D spheroids and exhibited enhanced epithelial-mesenchymal transition (EMT) pathway activity, whereas S2 displayed a more proliferative, MYC-driven phenotype with larger spheroid structures requiring higher seeding densities. Transcriptomic analysis revealed pathways associated with hypoxia, EMT and angiogenesis in 3D culture, highlighting the complexity introduced by dimensionality in tumour modelling. Critically, S1 showed higher sensitivity to doxorubicin than S2 (IC50 of 0.12 µM versus 1.28 µM, P=0.0001), indicating how clonal evolution can confound drug-response assays. Ultimately, our findings suggest that although STR profiling remains essential for cell line authentication, functionally distinct subpopulations can arise and coexist within the same culture, and their isolation may reveal divergent phenotypes that compromise reproducibility in preclinical cancer research.

Cells expressing PAX8 are the main source of homeostatic regeneration of adult mouse endometrial epithelium and give rise to serous endometrial carcinoma

ABSTRACT Humans and mice have cyclical regeneration of the endometrial epithelium. It is expected that such regeneration is ensured by tissue stem cells, but their location and hierarchy remain debatable. A number of recent studies have suggested the presence of stem cells in the mouse endometrial epithelium. At the same time, it has been reported that this tissue can be regenerated by stem cells of stromal/mesenchymal or bone marrow cell origin. Here, we describe a single-cell transcriptomic atlas of the main cell types of the mouse uterus and epithelial subset transcriptome and evaluate the contribution of epithelial cells expressing the transcription factor PAX8 to the homeostatic regeneration and malignant transformation of adult endometrial epithelium. According to lineage tracing, PAX8+ epithelial cells are responsible for long-term maintenance of both luminal and glandular epithelium. Furthermore, multicolor tracing shows that individual glands and contiguous areas of luminal epithelium are formed by clonal cell expansion. Inactivation of the tumor suppressor genes Trp53 and Rb1 in PAX8+ cells, but not in FOXJ1+ cells, leads to the formation of neoplasms with features of serous endometrial carcinoma, one of the most aggressive types of human endometrial malignancies. Taken together, our results show that the progeny of single PAX8+ cells represents the main source of regeneration of the adult endometrial epithelium. They also provide direct experimental genetic evidence for the key roles of the P53 and RB pathways in the pathogenesis of serous endometrial carcinoma and suggest that PAX8+ cells represent the cell of origin of this neoplasm.

Murine cell lines with defined mutations model different histological subtypes of epithelial ovarian cancer

ABSTRACT Preclinical modeling of epithelial ovarian cancer in immune-competent mice progressing to orthotopic, spontaneous tumors is challenging, requiring multiple genetic modifications in the host. Transplantable models using cell lines are easier to implement than spontaneous animal models, given that they reproduce the key disease characteristics. To create new in vivo ovarian tumor models, we generated 28 murine ovarian cancer cell lines with distinct genetic traits, such as deletion of Trp53, activation of KrasG12D, or deletion of Pten or KrasG12D/Pten−/− combination. Two distinct Trp53 null cell lines recapitulate high-grade serous histology when orthotopically injected into immune-competent, syngeneic hosts. Cells with Pten deletion trigger high-grade endometrioid tumors, and cells with dual KrasG12D activation and Pten deletion model carcinosarcoma. The cells express different tumor antigens, secrete varying levels of cytokines and chemokines, and trigger tumors with diverse inflammation profiles and various intratumoral T- and B-lymphocyte infiltration patterns. RNA-sequencing data from 16 cell lines reveal the gene expression profile across distinct models with different histotypes. This versatile collection of murine cell lines supports translationally relevant studies in ovarian cancer.

TP53 loss initiates chromosomal instability in fallopian tube epithelial cells

ABSTRACT High-grade serous ovarian cancer (HGSOC) originates in the fallopian tube epithelium and is characterized by ubiquitous TP53 mutation and extensive chromosomal instability (CIN). However, direct causes of CIN, such as mutations in DNA replication and mitosis genes, are rare in HGSOC. We therefore asked whether oncogenic mutations that are common in HGSOC can indirectly drive CIN in non-transformed human fallopian tube epithelial cells. To model homologous recombination deficient HGSOC, we sequentially mutated TP53 and BRCA1 then overexpressed MYC. Loss of p53 function alone was sufficient to drive the emergence of subclonal karyotype alterations. TP53 mutation also led to global gene expression changes, influencing modules involved in cell cycle commitment, DNA replication, G2/M checkpoint control and mitotic spindle function. Both transcriptional deregulation and karyotype diversity were exacerbated by loss of BRCA1 function, with whole-genome doubling events observed in independent p53/BRCA1-deficient lineages. Thus, our observations indicate that loss of the key tumour suppressor TP53 is sufficient to deregulate multiple cell cycle control networks and thereby initiate CIN in pre-malignant fallopian tube epithelial cells. This article has an associated First Person interview with the first author of the paper.

Biomimetic device and foreign body reaction cooperate for efficient tumour cell capture in murine advanced ovarian cancer

ABSTRACT Metastasis is facilitated by the formation of pre-metastatic niches through the remodelling of the extracellular matrix (ECM) promoted by haematopoietic and stromal cells. The impact of these primed sites is pronounced for intraperitoneal metastases, where the cavity-exposed ECM supports the attachment of the disseminating tumour cells. Likewise, implantation of biomaterial scaffolds influences metastatic progression systemically through a foreign body reaction (FBR). In this study, we integrated the concept of creating an artificial niche to capture tumour cells actively disseminating in the peritoneal cavity with a therapeutic strategy modulating the interactions of metastatic cells with the ECM. The aim was to transform a disseminated disease into a focal disease. For this, we designed and developed a ‘biomimetic’ ECM composed of a nonresorbable three-dimensional scaffold with collagen coating and characterized the FBR to the implanted biomaterial. We also analysed the safety of the implanted devices and their ability to capture tumour cells in different murine preclinical models of advanced ovarian cancer. Implantation of the biomimetic devices resulted in an initial inflammatory reaction that transformed progressively into a fibrous connective tissue response. The adhesive capabilities of the scaffold were improved with the ancillary effect of the FBR and showed clinical utility in terms of the efficacy of capture of tumour cells, disease focalization and survival benefit. These results demonstrated the performance and safety of this ‘biomimetic’ ECM in preclinical models of advanced ovarian cancer. Translated into the clinical setting, this new therapeutic strategy represents the possibility for control of peritoneal carcinomatosis upon primary ovarian debulking surgery and to expand the percentage of patients who are candidates for second rescue surgeries at the time of relapse.

Gestational trophoblastic disease: understanding the molecular mechanisms of placental tumours

ABSTRACT Gestational trophoblastic disease (GTD) describes a group of rare benign and cancerous lesions originating from the trophoblast cells of the placenta. These neoplasms are unconventional entities, being one of the few instances in which cancer develops from the cells of another organism, the foetus. Although this condition was first described over 100 years ago, the specific genetic and non-genetic drivers of this disease remain unknown to this day. However, recent findings have provided valuable insights into the potential mechanisms underlying this rare condition. Unlike previous reviews focused primarily on the clinical and diagnostic aspects of disease development, this Review consolidates the latest research concerning the role of genetics, epigenetics and microRNAs in the initiation and progression of GTD. By examining GTD from a molecular perspective, this Review provides a unique framework for understanding the pathogenesis and progression of this rare disease.