Multimodality animal rotation imaging system (Mars) for in vivo detection of intraperitoneal tumors

Adipose microenvironment promotes hypersialylation of ovarian cancer cells

Sialylation, the addition of negatively charged sialic acid sugars to terminal ends of glycans, is upregulated in most cancers. Hypersialylation supports multiple pro-tumor mechanisms such as enhanced migration and invasion, resistance to apoptosis and immune evasion. A current gap in knowledge is the lack of understanding on how the tumor microenvironment regulates cancer cell sialylation. The adipose niche is a main component of most peritoneal cancers' microenvironment. This includes ovarian cancer (OC), which causes most deaths from all gynecologic cancers. In this report, we demonstrate that the adipose microenvironment is a critical regulator of OC cell sialylation. In vitro adipose conditioning led to an increase in both ⍺2,3- and ⍺2,6-linked cell surface sialic acids in both human and mouse models of OC. Adipose-induced sialylation reprogramming was also observed in vivo from intra-peritoneal OC tumors seeded in the adipose-rich omentum. Mechanistically, we observed upregulation of at least three sialyltransferases, ST3GAL1, ST6GAL1 and ST3GALNAC3. Hypersialylated OC cells consistently formed intra-peritoneal tumors in both immune-competent mice and immune-compromised athymic nude mice. In contrast, hyposiaylated OC cells persistently formed tumors only in athymic nude mice demonstrating that sialylation impacts OC tumor formation in an immune dependent manner. To our knowledge, this is the first demonstration of the effect of adipose microenvironment on OC tumor sialylation. Our results set the stage for translational applications targeting sialic acid pathways in OC and other peritoneal cancers.

Lassa-VSV chimeric virus targets and destroys human and mouse ovarian cancer by direct oncolytic action and by initiating an anti-tumor response

Ovarian cancer is the third most common female cancer, with poor survival in later stages of metastatic spread. We test a chimeric virus consisting of genes from Lassa and vesicular stomatitis viruses, LASV-VSV; the native VSV glycoprotein is replaced by the Lassa glycoprotein, greatly reducing neurotropism. Human ovarian cancer cells in immunocompromised nude mice were lethal in controls. Chemotherapeutic paclitaxel and cisplatin showed modest cancer inhibition and survival extension. In contrast, a single intraperitoneal injection of LASV-VSV selectively infected and killed ovarian cancer cells, generating long-term survival. Mice with human ovarian cancer cells in brain showed rapid deterioration; LASV-VSV microinjection into brain blocked cancer growth, and generated long-term survival. Treatment of immunocompetent mice with infected mouse ovarian cancer cells blocked growth of non-infected ovarian cancer cells peritoneally and in brain. These results suggest LASV-VSV is a viable candidate for further study and may be of use in the treatment of ovarian cancer.

CBX7 binds the E-box to inhibit TWIST-1 function and inhibit tumorigenicity and metastatic potential

Deaths from ovarian cancer usually occur when patients succumb to overwhelmingly numerous and widespread micrometastasis. Whereas epithelial-mesenchymal transition is required for epithelial ovarian cancer cells to acquire metastatic potential, the cellular phenotype at secondary sites and the mechanisms required for the establishment of metastatic tumors are not fully determined. Using in vitro and in vivo models we show that secondary epithelial ovarian cancer cells (sEOC) do not fully reacquire the molecular signature of the primary epithelial ovarian cancer cells from which they are derived. Despite displaying an epithelial morphology, sEOC maintains a high expression of the mesenchymal effector, TWIST-1. TWIST-1 is however transcriptionally nonfunctional in these cells as it is precluded from binding its E-box by the PcG protein, CBX7. Deletion of CBX7 in sEOC was sufficient to reactivate TWIST-1-induced transcription, prompt mesenchymal transformation, and enhanced tumorigenicity in vivo. This regulation allows secondary tumors to achieve an epithelial morphology while conferring the advantage of prompt reversal to a mesenchymal phenotype upon perturbation of CBX7. We also describe a subclassification of ovarian tumors based on CBX7 and TWIST-1 expression, which predicts clinical outcomes and patient prognosis.

Adipocyte microenvironment promotes Bclxl expression and confers chemoresistance in ovarian cancer cells

Resistance to mitochondria-initiated apoptosis is a hallmark of chemoresistant cancer stem cells including CD44+/MyD88+ epithelial ovarian cancer (EOC) stem cells. This is controlled by members of the Bcl₂ family of proteins, which function as rheostats of mitochondrial stability. We observed a differential expression profile of Bcl₂ family members comparing the chemoresistant EOC stem cells and the chemosensitive CD44-/MyD88- EOC cells. Chemoresistant EOC stem cells surprisingly express higher levels of the pro-apoptotic members Bak and Bax compared to the chemosensitive EOC cells. In addition, whereas chemosensitive EOC cells preferentially express Bcl₂, chemoresistant EOC stem cells preferentially express Bcl_xl. In the EOC stem cells, 40% knock-down of Bcl_xl expression was sufficient to induce the full activation of caspases and this can be reversed by concurrent knock-down of Puma. More importantly, we demonstrate that Bcl_xl expression levels in EOC cells is dynamic and can be regulated by microenvironments that are enriched with the pro-inflammatory cytokine IL-6 such as the cancer stem cell and adipocyte niches. Adipocyte-induced upregulation of Bcl_xl correlated with acquisition of chemoresistance and thus demonstrates how a specific microenvironment can regulate the expression of apoptotic proteins and confer chemoresistance.

Characterization of "γ-Eye": a Low-Cost Benchtop Mouse-Sized Gamma Camera for Dynamic and Static Imaging Studies

PURPOSE

Several preclinical imaging systems are commercially available, but their purchase and maintenance costs make them unaffordable for the majority of small- and medium-sized groups. Taking into account the needs of average users, we developed "γ-eye", a mouse-sized, benchtop γ-camera suitable for in vivo scintigraphic imaging.

PROCEDURES

The γ-eye is based on two position-sensitive photomultiplier tubes, coupled to a CsI(Na) pixelated scintillator and a low-energy lead collimator with parallel hexagonal holes.

RESULTS

The spatial resolution of the system is 2 mm at 0 mm. The energy resolution is 26 % at 140 keV and the maximum recorded sensitivity 210 cps/MBq. The system was evaluated in a proof-of-concept animal study, using three different clinical Tc-99m-labeled radiopharmaceuticals. Phantom and animal studies demonstrate its ability to provide semiquantitative results even for short scans.

CONCLUSIONS

Systems' performance, dimensions, and cost make γ-eye a unique solution for efficient whole-body mouse nuclear imaging.

MicroRNA-222-3p/GNAI2/AKT axis inhibits epithelial ovarian cancer cell growth and associates with good overall survival

Ovarian carcinoma is the most lethal gynecologic tumor worldwide. Despite having developed molecular diagnostic tools and targeted therapies over the past few decades, patient survival is still quite poor. Numerous studies suggest that microRNAs are key regulators of many fundamental biological processes, including neoplasia and tumor progression. miR-222 is one of those miRNAs that has attracted much attention for its multiple roles in human diseases, especially cancer. The potential role of microRNAs in ovarian cancer has attracted much attention in recent years. Some of these microRNAs have been suggested as potential therapeutic targets for EOC patients. In this study, we sought to investigate the biologic functions of miR-222-3p in EOC carcinogenesis. Herein, we examined the expression of miR-222-3p in EOC patients, mouse models and cell lines, and found that higher expression of miR-222-3p was associated with better overall survival in EOC patients, and its level was negatively correlated with tumor growth in vivo. Furthermore, in-vitro experiments indicated that miR-222-3p inhibited EOC cell proliferation and migration, and decreased the phosphorylation of AKT. We identified GNAI2 as a target of miR-222-3p. We also found that GNAI2 promoted EOC cell proliferation, and is an activator of the PI3K/AKT pathway. We describe the characterization of a novel regulatory axis in ovarian cancer cells, miR-222-3p/GNAI2/AKT and its potential application as a therapeutic target for EOC patients.

Exploring brusatol as a new anti-pancreatic cancer adjuvant: biological evaluation and mechanistic studies

Pancreatic cancer is highly resistant to chemotherapeutic agents and is known to have a poor prognosis. The development of new therapeutic entities is badly needed for this deadly malignancy. In this study, we demonstrated for the first time that brusatol, a natural quassinoid isolated from a Chinese herbal medicine named Bruceae Fructus, possessed potent cytotoxic effect against different pancreatic adenocarcinoma cell lines. Its anti-pancreatic cancer effect was comparable to that of the first-line chemotherapeutic agents such as gemcitabine and 5-fluorouracil, with a more favorable safety profile. In addition, brusatol showed a synergistic anti-proliferative effect toward PANC-1 and Capan-2 cell lines when combined with gemcitabine or 5-fluorouracil. The results of flow cytometry suggested that brusatol combination treatment with gemcitabine or 5-fluorouracil was able to cause cell cycle arrest at G2/M phase, and accentuate apoptosis in PANC-1 cells. Moreover, brusatol deactivated gemcitabine/5-fluorouracil-induced NF-κB activation. Western blot analysis and qRT-PCR results showed that brusatol significantly down-regulated the expression of vimentin and Twist, and markedly stimulated the expression of E-cadherin, the key regulatory factors of the epithelial-mesenchymal transition process. Furthermore, treatment with combination of brusatol and gemcitabine or 5-fluorouracil significantly reduced in vivo tumor growth when compared with treatment of either brusatol or gemcitabine/5-fluorouracil alone. Taken together, these results have amply demonstrated that brusatol is a potent anti-pancreatic cancer natural compound, and the synergistic anti-pancreatic cancer effects of brusatol and gemcitabine/5-fluorouracil observed both in vitro and in vivo are associated with the suppression of epithelial-mesenchymal transition process, indicating that brusatol is a promising adjunct to the current chemotherapeutic regimen.

TRX-E-002-1 Induces c-Jun-Dependent Apoptosis in Ovarian Cancer Stem Cells and Prevents Recurrence In Vivo

Chemoresistance is a major hurdle in the management of patients with epithelial ovarian cancer and is responsible for its high mortality. Studies have shown that chemoresistance is due to the presence of a subgroup of cancer cells with stemness properties and a high capacity for tumor repair. We have developed a library of super-benzopyran analogues to generate potent compounds that can induce cell death in chemoresistant cancer stem cells. TRX-E-002-1 is identified as the most potent analogue and can induce cell death in all chemoresistant CD44(+)/MyD88(+) ovarian cancer stem cells tested (IC50 = 50 nmol/L). TRX-E-002-1 is also potent against spheroid cultures formed from cancer stem cells, chemosensitive CD44(-)/MyD88(-) ovarian cancer cells, and heterogeneous cultures of ovarian cancer cells. Cell death was associated with the phosphorylation and increased levels of c-Jun and induction of caspases. In vivo, TRX-E-002-1 given as daily intraperitoneal monotherapy at 100 mg/kg significantly decreased intraperitoneal tumor burden compared with vehicle control. When given in combination with cisplatin, animals receiving the combination of cisplatin and TRX-E-002-1 showed decreased tumor burden compared with each monotherapy. Finally, TRX-E-002-1 given as maintenance treatment after paclitaxel significantly delayed disease recurrence. Our results suggest that TRX-E-002-1 may fill the current need for better therapeutic options in the control and management of recurrent ovarian cancer and may help improve patient survival. Mol Cancer Ther; 15(6); 1279-90. ©2016 AACR.

Multiple blocks in the engagement of oxidative phosphorylation in putative ovarian cancer stem cells: implication for maintenance therapy with glycolysis inhibitors

Survival rate in ovarian cancer has not improved since chemotherapy was introduced a few decades ago. The dismal prognosis is mostly due to disease recurrence where majority of the patients succumb to the disease. The demonstration that tumors are comprised of subfractions of cancer cells displaying heterogeneity in stemness potential, chemoresistance, and tumor repair capacity suggests that recurrence may be driven by the chemoresistant cancer stem cells. Thus to improve patient survival, novel therapies should eradicate this cancer cell population. We show that in contrast to the more differentiated ovarian cancer cells, the putative CD44+/MyD88+ ovarian cancer stem cells express lower levels of pyruvate dehydrogenase, Cox–I, Cox-II, and Cox–IV, and higher levels of UCP2. Together, this molecular phenotype establishes a bioenergetic profile that prefers the use of glycolysis over oxidative phosphorylation to generate ATP. This bioenergetic profile is conserved in vivo and therefore a maintenance regimen of 2-deoxyglucose administered after Paclitaxel treatment is able to delay the progression of recurrent tumors and decrease tumor burden in mice. Our findings strongly suggest the value of maintenance with glycolysis inhibitors with the goal of improving survival in ovarian cancer patients.

Photodynamic diagnosis for detection of peritoneal carcinomatosis

BACKGROUND

Peritoneal carcinomatosis is the dissemination of cancer in the peritoneal cavity secondary to abdominal or extra-abdominal malignancies. Accurate assessment of the disease's burden is a challenge because of the complexity of the peritoneal cavity and the small size of the metastatic nodules. Photodynamic diagnosis (PDD) is an emerging technology in tumor diagnosis. A photosensitizer is administered, which is preferentially taken up by cancer cells. The photosensitizer emits fluorescence when exposed to a light of a specific wavelength. This helps distinguish cancer from normal tissues.

METHODS

We systematically reviewed the evidence for using PDD in detecting peritoneal carcinomatosis in both animal and human literature. Both Medline and EMBASE databases were searched (November 2014). The titles and the abstracts of all retrieved citations were inspected, and the full articles of the relevant articles were obtained.

RESULTS

A total of 12 human and 18 animal studies were included. Clinical studies have shown PDD to be a safe modality with no significant adverse effects. It increases the detection of malignant peritoneal nodules by 21%-34% in comparison with white light alone. The sensitivity and specificity of PDD were reported at 83%-100% and 95%-100%, respectively. These findings were supported by multiple animal studies, which have shown an increase in the sensitivity of tumor detection when using PDD (72%-91%) in comparison with white light alone (39%).

CONCLUSIONS

PDD is a promising modality, which improves the detection of peritoneal carcinomatosis lesions. Further research, however, should investigate the impact of PDD on the patients' therapeutic management and final outcomes.

Murine model for non-invasive imaging to detect and monitor ovarian cancer recurrence

Epithelial ovarian cancer is the most lethal gynecologic malignancy in the United States. Although patients initially respond to the current standard of care consisting of surgical debulking and combination chemotherapy consisting of platinum and taxane compounds, almost 90% of patients recur within a few years. In these patients the development of chemoresistant disease limits the efficacy of currently available chemotherapy agents and therefore contributes to the high mortality. To discover novel therapy options that can target recurrent disease, appropriate animal models that closely mimic the clinical profile of patients with recurrent ovarian cancer are required. The challenge in monitoring intra-peritoneal (i.p.) disease limits the use of i.p. models and thus most xenografts are established subcutaneously. We have developed a sensitive optical imaging platform that allows the detection and anatomical location of i.p. tumor mass. The platform includes the use of optical reporters that extend from the visible light range to near infrared, which in combination with 2-dimensional X-ray co-registration can provide anatomical location of molecular signals. Detection is significantly improved by the use of a rotation system that drives the animal to multiple angular positions for 360 degree imaging, allowing the identification of tumors that are not visible in single orientation. This platform provides a unique model to non-invasively monitor tumor growth and evaluate the efficacy of new therapies for the prevention or treatment of recurrent ovarian cancer.

In vivo optical imaging of brain tumors and arthritis using fluorescent SapC-DOPS nanovesicles

We describe a multi-angle rotational optical imaging (MAROI) system for in vivo monitoring of physiopathological processes labeled with a fluorescent marker. Mouse models (brain tumor and arthritis) were used to evaluate the usefulness of this method. Saposin C (SapC)-dioleoylphosphatidylserine (DOPS) nanovesicles tagged with CellVue Maroon (CVM) fluorophore were administered intravenously. Animals were then placed in the rotational holder (MARS) of the in vivo imaging system. Images were acquired in 10° steps over 380°. A rectangular region of interest (ROI) was placed across the full image width at the model disease site. Within the ROI, and for every image, mean fluorescence intensity was computed after background subtraction. In the mouse models studied, the labeled nanovesicles were taken up in both the orthotopic and transgenic brain tumors, and in the arthritic sites (toes and ankles). Curve analysis of the multi angle image ROIs determined the angle with the highest signal. Thus, the optimal angle for imaging each disease site was characterized. The MAROI method applied to imaging of fluorescent compounds is a noninvasive, economical, and precise tool for in vivo quantitative analysis of the disease states in the described mouse models.

Phenotypic modifications in ovarian cancer stem cells following Paclitaxel treatment

Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy. Despite initial responsiveness, 80% of EOC patients recur and present with chemoresistant and a more aggressive disease. This suggests an underlying biology that results in a modified recurrent disease, which is distinct from the primary tumor. Unfortunately, the management of recurrent EOC is similar to primary disease and does not parallel the molecular changes that may have occurred during the process of rebuilding the tumor. We describe the characterization of unique in vitro and in vivo ovarian cancer models to study the process of recurrence. The in vitro model consists of GFP+/CD44+/MyD88+ EOC stem cells and mCherry+/CD44-/MyD88- EOC cells. The in vivo model consists of mCherry+/CD44+/MyD88+ EOC cells injected intraperitoneally. Animals received four doses of Paclitaxel and response to treatment was monitored by in vivo imaging. Phenotype of primary and recurrent disease was characterized by quantitative polymerase chain reaction (qPCR) and Western blot analysis. Using the in vivo and in vitro models, we confirmed that chemotherapy enriched for CD44+/MyD88+ EOC stem cells. However, we observed that the surviving CD44+/MyD88+ EOC stem cells acquire a more aggressive phenotype characterized by chemoresistance and migratory potential. Our results highlight the mechanisms that may explain the phenotypic heterogeneity of recurrent EOC and emphasize the significant plasticity of ovarian cancer stem cells. The significance of our findings is the possibility of developing new venues to target the surviving CD44+/MyD88+ EOC stem cells as part of maintenance therapy and therefore preventing recurrence and metastasis, which are the main causes of mortality in patients with ovarian cancer.