Polyploid Giant Cells Research Articles

Single-cell morphological and transcriptome analysis unveil inhibitors of polyploid giant breast cancer cells in vitro

Considerable evidence suggests that breast cancer therapeutic resistance and relapse can be driven by polyploid giant cancer cells (PGCCs). The number of PGCCs increases with the stages of disease and therapeutic stress. Given the importance of PGCCs, it remains challenging to eradicate them. To discover effective anti-PGCC compounds, there is an unmet need to rapidly distinguish compounds that kill non-PGCCs, PGCCs, or both. Here, we establish a single-cell morphological analysis pipeline with a high throughput and great precision to characterize dynamics of individual cells. In this manner, we screen a library to identify promising compounds that inhibit all cancer cells or only PGCCs (e.g., regulators of HDAC, proteasome, and ferroptosis). Additionally, we perform scRNA-Seq to reveal altered cell cycle, metabolism, and ferroptosis sensitivity in breast PGCCs. The combination of single-cell morphological and molecular investigation reveals promising anti-PGCC strategies for breast cancer treatment and other malignancies.

Polyploid cell dynamics and death before and after PEG-treatment of a NIH/3T3 derived culture: vinblastine effects on the regulation of cell subpopulations heterogeneity

BackgroundNeoplastic subpopulations can include polyploid cells that can be involved in tumor evolution and recurrence. Their origin can be traced back to the tumor microenvironment or chemotherapeutic treatment, which can alter cell division or favor cell fusion, generating multinucleated cells. Their progeny, frequently genetically unstable, can result in new aggressive and more resistant to chemotherapy subpopulations. In our work, we used NIHs cells, previously derived from the NIH/3T3 line after serum deprivation, that induced a polyploidization increase with the appearance of cells with DNA content ranging from 4 to 24c. This study aimed to analyze the cellular dynamics of NIHs culture subpopulations before and after treatment with the fusogenic agent polyethylene glycol (PEG), which allowed us to obtain new giant polyploid cells. Successively, PEG-untreated and PEG-treated cultures were incubated with the antimicrotubular poison vinblastine. The dynamics of appearance, decrease and loss of cell subpopulations were evaluated by correlating cell DNA content to mono-multinuclearity resulting from cell fusion and division process alteration and to the peculiarities of cell death events.ResultsDNA microfluorimetry and morphological techniques (phase contrast, fluorescence and TEM microscopies) indicated that PEG treatment induced a 4–24c cell increase and the appearance of new giant elements (64–140c DNA content). Ultrastructural analysis and autophagosomal–lysosomal compartment fluorochromization, which allowed us to correlate cytoplasmic changes to death events, indicated that cell depletion occurred through distinct mechanisms: apoptotic death involved 2c, 4c and 8c cells, while autophagic-like death involved intermediate 12–24c cells, showing nuclear (lobulation/micronucleation) and autophagic cytoplasm alterations. Death, spontaneously occurring, especially in intermediate-sized cells, was increased after vinblastine treatment. No evident cell loss by death events was detected in the 64–140c range.ConclusionsPEG-treated NIHs cultures can represent a model of heterogeneous subpopulations originating from cell fusion and division process anomalies. Altogether, our results suggest that the different cell dynamics of NIHs subpopulations can affect the variability of responses to stimuli able to induce cell degeneration and death. Apoptptic, autophagic or hybrid forms of cell death can also depend on the DNA content and ability to progress through the cell cycle, which may influence the persistence and fate of polyploid cell descendants, also concerning chemotherapeutic agent action.

On the role of polyploid giant cells in oncogenesis and tumorigenesis

On the role of polyploid giant cells in oncogenesis and tumorigenesis

Myc promotes polyploidy in murine trophoblast cells and suppresses senescence.

The placenta is essential for reproductive success. The murine placenta includes polyploid giant cells that are crucial for its function. Polyploidy occurs broadly in nature but its regulators and significance in the placenta are unknown. We have discovered that many murine placental cell types are polyploid and have identified factors that license polyploidy using single-cell RNA sequencing. Myc is a key regulator of polyploidy and placental development, and is required for multiple rounds of DNA replication, likely via endocycles, in trophoblast giant cells. Furthermore, MYC supports the expression of DNA replication and nucleotide biosynthesis genes along with ribosomal RNA. Increased DNA damage and senescence occur in trophoblast giant cells without Myc, accompanied by senescence in the neighboring maternal decidua. These data reveal Myc is essential for polyploidy to support normal placental development, thereby preventing premature senescence. Our study, combined with available literature, suggests that Myc is an evolutionarily conserved regulator of polyploidy.

The Role of Mitotic Slippage in Creating a "Female Pregnancy-like System" in a Single Polyploid Giant Cancer Cell.

In our recent work, we observed that triple-negative breast cancer MDA-MB-231 cells respond to doxorubicin (DOX) via "mitotic slippage" (MS), discarding cytosolic damaged DNA during the process that provides their resistance to this genotoxic treatment. We also noted two populations of polyploid giant cells: those budding surviving offspring, versus those reaching huge ploidy by repeated MS and persisting for several weeks. Their separate roles in the recovery from treatment remained unclear. The current study was devoted to characterising the origin and relationship of these two sub-populations in the context of MS. MS was hallmarked by the emergence of nuclear YAP1/OCT4A/MOS/EMI2-positivity featuring a soma-germ transition to the meiotic-metaphase-arrested "maternal germ cell". In silico, the link between modules identified in the inflammatory innate immune response to cytosolic DNA and the reproductive module of female pregnancy (upregulating placenta developmental genes) was observed in polyploid giant cells. Asymmetry of the two subnuclei types, one repairing DNA and releasing buds enriched by CDC42/ACTIN/TUBULIN and the other persisting and degrading DNA in a polyploid giant cell, was revealed. We propose that when arrested in MS, a "maternal cancer germ cell" may be parthenogenetically stimulated by the placental proto-oncogene parathyroid-hormone-like-hormone, increasing calcium, thus creating a "female pregnancy-like" system within a single polyploid giant cancer cell.

CCR3 blockage elicits polyploidization associated with the signatures of epithelial-mesenchymal transition in carcinoma cell lines.

Malignant features such as the acquisition of metastatic ability, stemness of cells, and therapeutic resistance of cancer cells are associated with epithelial-mesenchymal transition (EMT) accompanied by changes in motility and morphology. Recent reports implicated that the formation of polyploid giant cancer cells (PGCCs) in human malignancy correlated with the EMT processes. Chemokines are often involved in the regulation of cancer cell migration into tissues, and various types of human cancers exhibit enhanced expression of chemokine receptors, which could augment intrinsic potentials such as invasive activity, proliferating ability, and survival capacity in cancer cells. Nevertheless, the contribution of CCR3 in malignant cancer cells is controversial because it is a well-known primal receptor for the migration of eosinophils, one of the cells of the innate immune system. Here, we explored the blockage of chemokine receptor CCR3 in carcinoma cell lines and found that inhibition of CCR3 induced the formation of polyploid giant cells and stabilization of β-catenin via the PI3K/Akt/GSK-3β signaling pathway, which are processes associated with EMT. As a result of CCR3 inhibition, converted cells acquired enhanced mobile and proliferation abilities. In summary, these data indicate that modulation of the CCR3/PI3K/Akt/GSK-3β signaling pathway regulates polyploidization associated with the EMT processes.

The effect of neoadjuvant chemotherapy on the structural and functional state of tumor cells in the secondary edematous form of breast cancer

Background. Secondary edematous form of breast cancer (SЕF BC) is the most aggressive type of BC that is characterized by rapid progression, high levels of metastasis, significant resistance to chemotherapy and radiotherapy. SЕF BC is not just a combination of cancer and local inflammation, but is a rare phenomenon in which the development of the tumor is primary. The processes of edema and inflammation occur because of lymph flow blockage by the formation of emboli from tumor cells (TC), which have elevated levels of E-cadherin, properties of polyploid cells and show signs of stem cells. Trimodal therapy methods are used for the treatment of SЕF BC, the main components of which are neoadjuvant systemic chemotherapy, surgery and adjuvant radiation therapy. However, the results of treatment remain insufficient, possibly due to the fact that the features of SЕF, the role of stem cells and inflammatory factors are not taken into account. Therefore, further research is needed in various fields of oncology, molecular biology, immunology, genetics, morphology, including electron microscopy, which is an important area for establishing the characteristics of both tumor cells and their environment. Purpose. Study of the neoadjuvant polychemotherapy influence on the structural and functional state of tumor cells of different molecular subtypes in the secondary edematous form of breast cancer.
 Materials and methods. Tumors of 29 patients with normal breast cancer and 32 patients with SЕF BC were studied. Receptors to estrogen (ER), progesterone (PR) and epidermal human growth factor 2 (HER2) were immunohistochemically determined before systemic neoadjuvant polychemotherapy (PCT). According to the receptor status, tumors were divided into 4 groups: 1 – triple negative («3-neg») tumors, 2 – HER2-positive («HER2») tumors, 3 – hormonally receptor («HP») tumors, 4 – tumorswith co-expression of hormonal receptors and HER2 («HR + HER2»). For polychemotherapy (PCT) the regimen (AСx4–Рx4) was used.The ultrastructure of the tumor cells (TC) was examined using standard electron microscopy methods. In all study groups, the frequency of cases with pronounced therapeutic pathomorphosis (PTPM) was determined, as well as the frequency of tumors with luminal and non-luminal symptoms after treatment. The obtained data were calculated using non-parametric methods with the software package for PC «Biostat» application and using a non-parametric criterion of the most plausible assessment of reliability for small selections (Pmp).
 Results. It was found that PCT in patients with conventional BC causes a pronounced therapeutic pathomorphosis (РТPM) of most tumors of the receptor groups «3-neg», «HER2» and «HR+HER2», compared with the group «HR», where no case of РTPM was observed. At SЕF BC the frequency of tumors with the pronounced pathomorphosis in groups with nonluminal subtypes and co-expression of receptors decreases, that for group «3-neg» is reliable. This indicates increased chemoresistance of triple negative tumors. In the group of hormone receptor tumors at SEF, this index increases significantly. Analysis of the ultrastructure of tumors of different molecular subtypes showed that most of the processes of damage and accompanying reactions to the action of PCT are identical for both forms of BC. Thus, in response to chemotherapy, different types of cell death: necrotic, dark cell, apoptotic; processes of cell nucleus damage: presence of dinuclear PCs, cells with micronuclei; disturbance of the microvessels structure: edema and condensation of the endothelial cells cytoplasm and their exfoliation; activation of phagocytosis and immune processes are observed. Only SЕF is characterized by the presence of TCs and emboli in capillaries, as well as a significantly increased frequency of giant polyploid tumor cells. It was also found that after PCT in patients with normal BC preserved tumor cells show mainly luminal signs (72.7–100%). However, in SЕF BC such reaction occurs only for hormone-receptor subtypes and the group with co-expression of receptors, whereas for tumors of three negative and HER2-positive subtypes the frequency of luminal signs is lower than in conventional BC and is 33.3%, p ≤ 0.05 and 66.7%, respectively.
 Conclusions. Peculiarities of SЕF BC in contrast to the usual form of BC are significantly reduced sensitivity of 3-negative cancer to chemotherapy and the tendency to chemoresistance of molecular subtypes with the presence of HER2; significant survival after PCT tumors with non-luminal cells characteristic in the group of 3-negative cancer, while in other receptor subtypes most tumors have luminal features; probably increased after chemotherapy the number of tumors with giant polyploid cells. It is possible that the features of SЕF BC are associated with the presence of polyploid TCs resistant to chemotherapy, and both inflammation and chemotherapy may play a role in stimulating their formation.

Mutation in SF3B1 gene promotes formation of polyploid giant cells in Leukemia cells

Giant cells with polyploidy, termed polyploid giant cells, have been observed during normal growth, development, and pathologic states, such as solid cancer progression and resistance to therapy. Functional studies of polyploidal giant cancer cells (PGCC) provided evidence that they arise when normal diploid cells are stressed, show stem cell-like properties, and give rise to tumors. In the present study, we report in K562 leukemia cell line that introduction of the hotspot K700E mutation in the gene SF3B1 using CRISPR/Cas9 method results in an increased frequency of multinucleated polyploid giant cells resistant to chemotherapeutic agent and serum starvation stress. These giant cells with higher ploidy are distinct from multinucleated megakaryocytes, are proliferative, and are characterized by increased accumulation of mitochondria. PGCC have been previously documented in solid tumors. This is the first report describing PGCCs in a cell line derived from a liquid cancer where increased frequency of PGCCs is linked to a specific genetic event. Since SF3B1 mutations are predominantly seen in MDS and other hematologic malignancies, our current findings will have significant clinical implications.

Polyploid giant cancer cells and their role in the formation of resistance to therapeutic treatment

The review considers the properties of polyploid giant tumor cells a new target for the development of cancer therapy. Various number of polyploid giant tumor cells are detected in almost all human solid tumors. Their number increases under the influence of hypoxia, radiation, and after chemotherapy. Previously, these cells were not considered to be worth studying as they do not proliferate and eventually die as a result of one of the cell death mechanisms action. Recent data have demonstrated that polyploid giant cells can give rise to daughter cells that possess tumorigenicity and are characterized as stem tumor cells. Giant tumor cells and daughter cells are involved in the processes of metastasis, recurrence, drug resistance formation and radio-resistance of tumors. The search is under way for molecular targets that could prevent the appearance or contribute to the elimination of previously formed polyploid giant tumor cells. The combination of traditional therapy that causes the death of proliferating tumor cells and allows their elimination, with the use of tools that could prevent the appearance of resistant polyploid giant cells and their daughter cells, can be the key to the effective treatment of malignancies.

IL33 Is a Key Driver of Treatment Resistance of Cancer.

Recurrence and treatment resistance are major causes of cancer-associated death. There has been a growing interest in better understanding epithelial-mesenchymal transition, stemness of cancer cells, and exhaustion and dysfunction of the immune system for which numerous genomic, proteomic, microenvironmental, and immunologic mechanisms have been demonstrated. However, practical treatments for such patients have not yet been established. Here we identified IL33 as a key driver of polyploidy, followed by rapid proliferation after treatment. IL33 induction transformed tumor cells into polyploid giant cells, showing abnormal cell cycle without cell division accompanied by Snail deregulation and p53 inactivation; small progeny cells were generated in response to treatment stress. Simultaneously, soluble IL33 was released from tumor cells, leading to expansion of receptor ST2-expressing cells including IL17RB+GATA3+ cells, which promoted tumor progression and metastasis directly and indirectly via induction of immune exhaustion and dysfunction. Blocking IL33 with a specific mAb in murine IL33+ metastatic tumor models abrogated negative consequences and successfully elicited antitumor efficacy induced by other combined treatments. Ex vivo assays using tumor tissues and peripheral blood mononuclear cells of patients with cancer validated the clinical relevancy of these findings. Together, these data suggest that targeting the IL33-ST2 axis is a promising strategy for diagnosis and treatment of patients likely to be resistant to treatments in the clinical settings. SIGNIFICANCE: These findings indicate that the functional role of IL33 in cancer polyploidy contributes to intrinsic and extrinsic mechanisms underlying treatment failure.

Senescence in polyploid giant cancer cells: A road that leads to chemoresistance

Cellular senescence has been associated with age-related diseases, wound healing, fibrosis, diabetes and cancer. Senescent cells lack the capacity to proliferate, but are known to aggravate tumorigenesis. The polyploid giant cells arise from the cancer cell population mainly due to genotoxic stress caused by chemotherapy and/or radiotherapy. They exhibit features of senescence and have been reported to secrete an array of cytokines, chemokines and growth factors. These small molecules can bind to their receptors located on the surface of neighboring cells and activate/deactivate relevant signaling pathways, thereby modulating the tumor microenvironment. Some of these signaling cascade(s) might play a role in imparting therapy resistance to the cancer cells. This review throws light on the incidence of senescence and how the senescent polyploid giant cells affect the tumor microenvironment. Their role in giving rise to chemoresistant cancer cell population as well as acquired chemoresistance in the neighboring cancer cells along with various potential and established therapeutic avenues have also been discussed.

Abstract 4636: Oncogenic Notch triggers neoplastic-tumorigenesis in a transition-zone like tissue microenvironment

Abstract The “seed and soil” hypothesis proposed by Stephen Paget (1889) highlights the importance of tissue microenvironment for secondary tumor formation. The microenvironment that promotes primary tumor origination, however, remains largely unclear. Transition zones, where two types of epithelial tissue meet, have been characterized as high-risk sites for tumorigenesis. Here we show that the Drosophila salivary gland (SG) imaginal ring (ImR) can be used as a model to study tumorigenesis in transition zones. We found that constitutive activation of Notch signaling during the third larval instar drives overproliferation and tumor formation in the SG ImR. Interestingly, tumorigenesis always occurs at the posterior end of the ImR, which is a transitional area between the polyploid giant cells and diploid ImR cells. These Notch-induced tumors display disrupted epithelial organization, grow continuously and can metastasize once transplanted into the abdomen of adult flies, suggesting that they have the characteristics of malignant neoplasms. Further analyses revealed that the SG ImR transition zone possesses endogenously high levels of Janus kinase/signal transducers and activators of transcription (JAK-STAT) and c-Jun amino-terminal kinases (JNK), both of which are necessary for tumor growth. In this region, JNK signaling induces the expression of matrix metalloproteinase 1 (MMP1), which is also required for tumor formation in this model system. Furthermore, we found that ectopic MMP1 expression can transform the anterior end of the SG ImR, which is normally refractory to oncogenic Notch-induced tumorigenesis, into a tumor hotspot. Together, these studies reveal that local endogenous activation of JNK and JAK-STAT signaling creates a niche-like tissue microenvironment that is susceptible to oncogene-induced neoplastic tumor formation. Citation Format: Wu-Min Deng, Sheng-An Yang. Oncogenic Notch triggers neoplastic-tumorigenesis in a transition-zone like tissue microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4636.

Abstract 4676: Cancer stem cell induces chemoresistance in breast cancer via macrophage migration inhibitory factor mediated activation of AKT pathway

Abstract Chemoresistance is one of the significant problems of cancer management. Cellular crosstalk in tumor microenvironment plays a vital role in regulating the chemoresistance in cancer. Cancer stem cell (CSC) is one of the key players in the regulation of chemoresistance in cancer, and they modulate the tumor microenvironment to enhance the resistance to anti-cancer therapy. However, the exact mechanism by which CSC can influence the cellular crosstalk in the tumor microenvironment is mostly unknown. Macrophage migration inhibitory factor (MIF) is attributed to inducing therapeutic resistance in several cancers. We previously found a close relation of MIF secretion with a group of polyploid giant cells in chemoresistant breast cancer. MIF secretion was increased in the media of the mammosphere of MDA MB 231 cell (231) as well as Doxorubicin (Dox) and 5-Fluorouracil (5FU) resistant 231 cells. MIF secretion also increased upon treating 231 with Dox and 5FU in a time-dependent manner. Addition of recombinant MIF in culture medium increased the resistance of 231 to chemotherapeutic agents, and a similar phenomenon was also observed upon treatment with conditioned medium from CSC. Chemoresistant breast cancer is enriched with the CSC population, and hence we hypothesized that the MIF was secreted from CSC populations and had a significant role in the regulation of chemoresistance in breast cancer. MIF expression was also increased in Chemoresistant breast cancer tissues compare to non-resistant ones. MIF also induced anti-apoptotic protein Bcl2 and Bcl-xl by downregulating Bax and Bad as well as contributed to the chemoresistant phenotype. Conditioned media from CSC and exogenous MIF were unable to induce chemoresistance in parental 231 cell line in the presence of 4-IPP, a MIF inhibitor. The anti-apoptotic effect of exogenous MIF was also reversed by the inhibitor. Thus we confirmed that MIF played a significant role in the regulation of resistant phenotype in breast cancer microenvironment. Upon further analysis of molecular pathways, we found phosphorylation of AKT corresponded with the MIF secretion in CSC as well as chemoresistant 231 cell lines. MIF was able to increase the level of phosphorylated AKT in 231 cell line in a dose-dependent manner. When chemoresistant 231 cells were treated with MIF inhibitor, the AKT phosphorylation was inhibited. Silencing the AKT pathway via siRNA reversed the sensitization of exogenous MIF and reduced the resistance of both parental 231 as well as resistant 231 cells. So, overall we conclude that MIF plays a crucial role in inducing chemoresistance in breast cancer by upregulating anti-apoptotic protein Bcl2 and Bcl-xl & downregulating Bax and Bad through AKT phosphorylation. The MIF is mainly secreted by CSC population during self-renewal or stress caused by chemotherapy which activates anti-apoptotic pathways in tumor microenvironment. Citation Format: Subhayan Das, Moumita Kundu, Aditya Parekh, Deblina Bharadwaj, Mahitosh Mandal. Cancer stem cell induces chemoresistance in breast cancer via macrophage migration inhibitory factor mediated activation of AKT pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4676.

Alterations of The Stem-Like Properties in The Breast Cancer Cell Line MDA-MB-231 Induced by Single Pulsed Doxorubicin Treatment

Abstract Development of chemoresistance remains a significant limitation for the treatment of cancer and contributes to recurrence of the disease. Both intrinsic and acquired mechanisms of chemoresistance are characteristics of cancer stem cells (CSCs) or stem-like cells (SLCs). The aim of the study was to assess the stem-like properties in the breast cancer cell line MDA-MB-231 during and after pulsed treatment with doxorubicin (DOX) in comparison to the untreated controls.The experimental cultures were exposed to therapeutic concentration of DOX for 48 hours (treatment cultures), and subcultured to post-treatment cultures 24 hours after the removal of DOX. Stem-like properties of the cellular populations in the treatment and post--treatment cultures were assessed by the expression of the stem-cell marker genes (CD24, CD44, ITGA6, ITGB1, POU5F1, NANOG, ALDH1A1), colony-formation efficiency, growth rates, and sensitivity to DOX, 5-fluorouracil (5FU), cisplatin (CIS), and vinblastine (VBL). Exposure to DOX induced formation of giant polyploid cells that persisted in the post-treatment culture. The recovery period was characterised by a decrease in the proliferation rate, viability, and cellular adherence. The post-treatment cultures displayed decreased sensitivity to DOX and increased sensitivities to 5FU, CIS, and VBL. Cells treated with DOX displayed increased expression levels of CD24, CD44, and ALDH1A, while their expression levels at least partially normalised in the post-treatment culture. The post-treatment cultures demonstrated significantly increased colony-formation ability. During treatment with sub-lethal levels of doxorubicin and during the acute recovery period, the survival mechanisms in the breast cancer cell line MDA-MB-231 may be mediated by formation of the cellular population with stem-like properties.

A Microbore Tubing Based Spiral for Multistep Cell Fractionation.

Cells were separated with the aid of a multistep spiral fractionation device, utilizing hydrodynamic forces in a spiral tubing. The spiral was fabricated using "off-the-shelf" microbore tubing, allowing for cheap and fast prototyping to achieve optimal cell separation. As a first step, a model system with 20 and 40 μm beads was used to demonstrate the effectiveness of the multistep separation device. With an initial purity of 5%, a separation purity of 83% was achieved after a two-step separation with the addition of 0.1% polyethylene glycol (PEG)-8000. Next, doxorubicin-resistant polyploid giant breast cancer cells (MDA-MB-231) were separated from doxorubicin-sensitive monoploid small breast cancer cells in the same fashion as the beads, resulting in a purity of around 40%, while maintaining a cell viability of more than 90%. Combined with basic cell analytical methods, the hydrodynamic separation principle of the device could be envisaged to be useful for a variety of cell fractionation needs in cell biology and in clinical applications.

Abstract 2631: Cancer associated macrophage-like (CAMLs) cells in blood predict progression and survival for all stages of solid tumors

Abstract Background: We previously demonstrated that cancer associated macrophage-like cells (CAMLs) are cancer specific giant polyploid cells circulating in the blood of patients with solid tumors. Building on our initial discovery, others have shown that these hyperploidy cells are an innate immune response that is associated with decreased survival. However to date, no studies have been done to elucidate their clinical significance as in relation to the various stages of malignant disease. We established a 4 year prospective study of 315 patients from a variety of solid tumors (breast, prostate, lung, renal cell, pancreas, and esophageal) comparing the morphological properties of CAMLs in both early and late stage disease as they relate to progression free and overall survival (PFS/OS). These data suggest that CAML size appears have a strong negative correlation with progression and survival of cancer patients, irregardless of stage of disease, indicating their possible use as a non-invasive blood based biomarker in solid tumors. Methods: A prospective multi-institutional study used anonymized peripheral blood from 315 cancer patients [stage I (n=62), stage II (n=72), stage III (n=69) & stage IV (n=106)] from subjects with breast (n=59), esophageal (n=27), lung (n=59), renal cell carcinoma (n=37), prostate (n=74), pancreas cancers (n=59). CAMLs were isolated by the CellSieve™ microfiltration technique at 5 institutions and stained for cytokeratin 8, 18, & 19, CD14 and CD45. After imaging, a size based threshold ≥50µm was used to separate the patient cohorts, based on previously published assessments. Results: At least one CAML was found in 92% of cancer patients (n=289/315), with the lowest sensitivity in stage 1 (86%), followed by stage 2 (90%), stage 3 (97%) and stage 4 (95%). The property of CAML size was then evaluated. Overall, CAMLs of <50µm in size had superior PFS (HR: 3.8; 95% CI 2.8-5.3; p<0.001) and OS (HR=3.8; 95% CI 2.6-5.7;p<0.001) than those with ≥50 µm CAMLs. By each stage individually, stage 1 (PFS HR=7.5; 95% CI 3.2-17.7; p<0.001), stage II (PFS; HR=4.1; 95% CI 1.9-8.8; p<0.001), stage III (PFS HR=3.1; 95% CI 1.7-5.7; p=0.007), and stage IV (PFS HR=2.7; 95% CI 1.6-4.4; p<0.001). Conclusions: In this first large scale prospective study of the clinical utility of CAMLs, it appears that they are present in every stages of invasive solid tumor malignancies, with prevalence increasing with stage. Interestingly decreased CAML size was found to be associated with improved outcome and longer PFS. These data suggest that CAML detection and size assessment constitute a new real time predictor of progression, and survival in both early and late stage disease indicating the need for additional validation studies. Citation Format: Daniel L. Adams, Steven H. Lin, R. Katherine Alpaugh, Thai Ho, Jeffrey R. Marks, Stuart S. Martin, Susan Tsai, Saranya Chumsri, Cha-Mei Tang, Massimo Cristofanilli, Raymond Bergan. Cancer associated macrophage-like (CAMLs) cells in blood predict progression and survival for all stages of solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2631.

Roles of Polyploid/Multinucleated Giant Cancer Cells in Metastasis and Disease Relapse Following Anticancer Treatment.

Tumors and tumor-derived cell lines contain polyploid giant cells with significantly elevated genomic content, often with multiple nuclei. The frequency of giant cells can increase markedly following anticancer treatment. Although giant cells enter a dormant phase and therefore do not form macroscopic colonies (aggregates of ≥50 cells) in the conventional in vitro colony formation assay, they remain viable and metabolically active. The purpose of this commentary is to underscore the potential importance of polyploid/multinucleated giant cells in metastasis and cancer recurrence following exposure to anticancer agents. We also discuss the possibility that most preclinical (cell-based and animal model) drug discovery approaches might not account for delayed responses that are associated with dormant giant cells.

JNK and Yorkie drive tumor progression by generating polyploid giant cells in Drosophila.

Epithelial cancer tissues often possess polyploid giant cells, which are thought to be highly oncogenic. However, the mechanisms by which polyploid giant cells are generated in tumor tissues and how such cells contribute to tumor progression remain elusive. We previously noticed in Drosophila imaginal epithelium that cells mutant for the endocytic gene rab5 exhibit enlarged nuclei. Here we find that mutations in endocytic 'neoplastic tumor-suppressor' genes, such as rab5, vps25, erupted, or avalanche result in generation of polyploid giant cells. Genetic analyses on rab5-defective cells reveal that cooperative activation of JNK and Yorkie generates polyploid giant cells via endoreplication. Mechanistically, Yorkie-mediated upregulation of Diap1 cooperates with JNK to downregulate the G2/M cyclin CycB, thereby inducing endoreplication. Interestingly, malignant tumors induced by Ras activation and cell polarity defect also consist of polyploid giant cells, which are generated by JNK and Yorkie-mediated downregulation of CycB. Strikingly, elimination of polyploid giant cells from such malignant tumors by blocking endoreplication strongly suppressed tumor growth and metastatic behavior. Our observations suggest that JNK and Yorkie, two oncogenic proteins activated in many types of human cancers, cooperatively drive tumor progression by generating oncogenic polyploid giant cells.

Abstract 3074: Selective lethality of cisplatin in pancreatic cancer is dependent on mitotic functions of BRCA2

Abstract Pancreatic ductal adenocarcinoma (PDA) is an aggressive malignancy with a 5-year survival rate of just 8%. Mutations in BRCA2 are among the most common known germline alterations that predispose to PDA. While the sensitivity of BRCA2-mutant breast and ovarian tumors to platinum compounds has long been recognized, the recent approval a PARP inhibitor in BRCA2-mutant ovarian cancer confers hope that such tumors might be targeted with greatly reduced toxicity. To test whether PDA exhibits a similar genetic susceptibility to these agents, we carried out preclinical intervention studies in Kras/p53-mutant genetically engineered mouse models (KPC mice) with or without the additional mutation of BRCA2 (KPCB2 mice). Mice were enrolled based on 3D ultrasound imaging criteria to assure similar initial tumor burden, and tumor growth was monitored longitudinally by ultrasound. To our surprise, loss of Brca2 failed to sensitize pancreatic tumors to Parp inhibition and did not provide additional benefit in combination with cisplatin treatment. By contrast, cisplatin induced substantial regressions in most KPCB2 tumors, leading to a >3-fold increase in overall survival, while having no effect on the growth or survival of mice with wild-type BRCA2. More surprisingly, the efficacy of cisplatin was not shared with oxaliplatin, even at higher doses. While BRCA2 is primarily known for its role in homology-directed repair, a network biology analysis of the function of BRCA2 in human pancreatic cancer led us to investigate the role of BRCA2 in mitosis. Wild type BRCA2 protein localizes to the midbody- a structure formed during the final stages of telophase- and plays and poorly understood role in the final abscission of cytoplasm between two dividing cells. Timelapse video microscopy of KPCB2 tumor cells treated once weekly for 2 hours with cisplatin revealed the frequent induction of endoreduplication and eventual formation of polyploid giant cells subsequent death. Similar cells were found throughout KPCB2 tumors during regression in response to cisplatin treatment, but were largely absent from tumors in other treatment arms. Mechanism studies found that BRCA2 deficient PDA cells are susceptible to replicative stress following cisplatin treatment that selectively leads to the formation of radial chromosomes that cannot be resolved during mitosis. These studies argue for the consideration of cisplatin-based (rather than oxaliplatin-based) regimens for the treatment of BRCA2-mutant pancreatic tumors. Citation Format: Barbara Orelli, Hans C. Maurer, Carmine Palermo, Steven A. Sastra, Kenneth P. Olive. Selective lethality of cisplatin in pancreatic cancer is dependent on mitotic functions of BRCA2 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3074. doi:10.1158/1538-7445.AM2017-3074

The Cytolethal Distending Toxin Subunit CdtB of Helicobacter hepaticus Promotes Senescence and Endoreplication in Xenograft Mouse Models of Hepatic and Intestinal Cell Lines.

Cytolethal distending toxins (CDTs) are common among pathogenic bacteria of the human and animal microbiota. CDTs exert cytopathic effets, via their active CdtB subunit. No clear description of those cytopathic effects has been reported at the cellular level in the target organs in vivo. In the present study, xenograft mouse models of colon and liver cell lines were set up to study the effects of the CdtB subunit of Helicobacter hepaticus. Conditional transgenic cell lines were established, validated in vitro and then engrafted into immunodeficient mice. After successful engraftment, mice were treated with doxycyclin to induce the expression of transgenes (red fluorescent protein, CdtB, and mutated CdtB). For both engrafted cell lines, results revealed a delayed tumor growth and a reduced tumor weight in CdtB-expressing tumors compared to controls. CdtB-derived tumors showed γ-H2AX foci formation, an increase in apoptosis, senescence, p21 and Ki-67 nuclear antigen expression. No difference in proliferating cells undergoing mitosis (phospho-histone H3) was observed. CdtB intoxication was also associated with an overexpression of cytokeratins in cells at the invasive front of the tumor as well as an increase in ploidy. All these features are hallmarks of endoreplication, as well as aggressiveness in cancer. These effects were dependent on the histidine residue at position 265 of the CdtB, underlying the importance of this residue in CdtB catalytic activity. Taken together, these data indicate that the CdtB triggers senescence and cell endoreplication leading to giant polyploid cells in these xenograft mouse models.