Rapid and Sensitive Detection of Cancer Cells with Activatable Fluorescent Probes for Enzyme Activity.

Fluorescence (FL)-guided detection of cancer is one of the most promising approaches to achieve intraoperative assessment of surgical margins. Enzymes, such as aminopeptidase, carboxypeptidase, and glycosidase, whose activities are increased in cancer, have attracted great interest as imaging targets for rapid and sensitive visualization of cancerous tissues with fluorescent probes. Activatable probes, which are initially nonfluorescent but become strongly fluorescent upon rapid one-step cleavage of their substrate moiety by the target enzyme, are especially promising for practical clinical application during surgical or endoscopic procedures due to the highly amplified FL change generated by enzyme-catalyzed turnover at lesion sites. Here, we describe robust protocols for using activatable fluorescent probes targeting cancer-associated enzyme activities to visualize cultured cancer cells, metastatic cancer in a mouse model, and cancerous lesions in surgical specimens from patients.

Targeting eukaryotic elongation factor-2 kinase suppresses the growth and peritoneal metastasis of ovarian cancer.

Ovarian cancer (OC) is the deadliest gynecological cancer and is currently incurable with standard treatment regimens. Early invasion, intraperitoneal metastasis, and an aggressive course are the hallmarks of OC. The major reason for poor prognosis is a lack of molecular targets and highly effective targeted therapies. Therefore, identification of novel molecular targets and therapeutic strategies is urgently needed to improve OC survival. Herein we report that eukaryotic elongation factor-2 kinase (EF2K) is highly upregulated in primary and drug-resistant OC cells and its expresssion associated with progression free survival TCGA database) and promotes cell proliferation, survival, and invasion. Downregulation of EF2K reduced expression of integrin ß1 and cyclin D1 and the activity of the Src, phosphoinositide 3-kinase/AKT, and nuclear factor-κB signaling pathways. Also, in vivo, therapeutic targeting of EF2K by using single-lipid nanoparticles containing siRNA led to substantial inhibition of ovarian tumor growth and peritoneal metastasis in nude mouse models. Furthermore, EF2K inhibition led to robust apoptosis and markedly reduced intratumoral proliferation in vivo in ovarian tumor xenografts and intraperitoneal metastatic models. Collectively, our data suggest for the first time that EF2K plays an important role in OC growth, metastasis, and progression and may serve as a novel therapeutic target in OCs.

Prevalence of Lynch syndrome in women with mismatch repair-deficient ovarian cancer.

BACKGROUND: There are limited data on the prevalence of Lynch syndrome (LS) in women with primary ovarian cancer with mismatch repair deficiency (MMR-D) by immunohistochemistry (IHC). MATERIALS AND METHODS: Three hundred and eight cases of primary ovarian, fallopian, and peritoneal cancer between January 2012 and December 2019 were evaluated for MMR-D by IHC. The incidence of LS in this cohort was evaluated. RESULTS: MMR-D by IHC was identified in 16 of 308 (5.2%) (95% CI: 3.2%-8.3%) primary ovarian-related cancers. Most cases with MMR-D were endometrioid (n = 11, 68.7%); (95% CI: 44.2%-86.1%). MSH2/MSH6 protein loss was detected in eight cases (50.0%); (95% CI: 28.0%-72.0%) and MLH1/PMS2 protein loss was detected in four cases (25.0%); (95% CI: 9.7%-50.0%). MSH6 protein loss was detected in two cases (12.5%); (95% CI: 2.2%-37.3%) and PMS2 protein loss was detected in two cases (12.5%); (95% CI: 2.2%-37.3%). All four cases with MLH1/PMS2 protein loss had MLH1 promotor hypermethylation. All 12 women with ovarian cancer suggestive of LS underwent germline testing and 8 (66.6%); (95% CI: 38.8%-86.5%) were confirmed to have LS. CONCLUSIONS: Most ovarian cancers with somatic MMR-D were confirmed to have LS in this cohort. Germline testing for LS in addition to BRCA1/2 for all women with an epithelial ovarian cancer would be efficient and would approach 100% sensitivity for identifying Lynch syndrome. Utilization of a multigene panel should also be considered, given the additional non-Lynch germline mutation identified in this cohort.

MILO/ENGOT-ov11: Binimetinib Versus Physician's Choice Chemotherapy in Recurrent or Persistent Low-Grade Serous Carcinomas of the Ovary, Fallopian Tube, or Primary Peritoneum.

PURPOSE: Low-grade serous ovarian carcinomas (LGSOCs) have historically low chemotherapy responses. Alterations affecting the MAPK pathway, most commonly KRAS/BRAF, are present in 30%-60% of LGSOCs. The purpose of this study was to evaluate binimetinib, a potent MEK1/2 inhibitor with demonstrated activity across multiple cancers, in LGSOC. METHODS: This was a 2:1 randomized study of binimetinib (45 mg twice daily) versus physician's choice chemotherapy (PCC). Eligible patients had recurrent measurable LGSOC after ≥ 1 prior platinum-based chemotherapy but ≤ 3 prior chemotherapy lines. The primary end point was progression-free survival (PFS) by blinded independent central review (BICR); additional assessments included overall survival (OS), overall response rate (ORR), duration of response (DOR), clinical-benefit rate, biomarkers, and safety. RESULTS: A total of 303 patients were randomly assigned to an arm of the study at the time of interim analysis (January 20, 2016). Median PFS by BICR was 9.1 months (95% CI, 7.3 to 11.3) for binimetinib and 10.6 months (95% CI, 9.2 to 14.5) for PCC (hazard ratio,1.21; 95%CI, 0.79 to 1.86), resulting in early study closure according to a prespecified futility boundary after 341 patients had enrolled. Secondary efficacy end points were similar in the two groups: ORR 16% (complete response [CR]/partial responses[PRs], 32) versus 13% (CR/PRs, 13); median DOR, 8.1 months (range, 0.03 to ≥ 12.0 months) versus 6.7 months (0.03 to ≥ 9.7 months); and median OS, 25.3 versus 20.8 months for binimetinib and PCC, respectively. Safety results were consistent with the known safety profile of binimetinib; the most common grade ≥ 3 event was increased blood creatine kinase level (26%). Post hoc analysis suggests a possible association between KRAS mutation and response to binimetinib. Results from an updated analysis (n = 341; January 2019) were consistent. CONCLUSION: Although the MEK Inhibitor in Low-Grade Serous Ovarian Cancer Study did not meet its primary end point, binimetinib showed activity in LGSOC across the efficacy end points evaluated. A higher response to chemotherapy than expected was observed and KRAS mutation might predict response to binimetinib.

Malignant mesothelioma in situ: morphologic features and clinical outcome.

The existence of an in situ phase of malignant mesothelioma has long been postulated but until recently has been impossible to prove. Here we describe ten patients with mesothelioma in situ, defined by a single layer of surface mesothelial cells showing loss of BAP1 nuclear immunostaining, no evidence of tumor by imaging and/or by direct examination of the pleura/peritoneum, and no invasive mesothelioma developing for at least 1 year. Nine cases were pleural and one peritoneal. Most patients were biopsied for repeated effusions of unknown etiology; in two patients mesothelioma in situ was found incidentally in lung cancer resections. In addition to surface mesothelium with BAP1 loss, one case had a surface papillary proliferation with BAP1 loss, and two cases had a small (few millimeter) nodule with BAP1 loss. CDKN2A was deleted by FISH in one of eight cases. Methylthioadenosine phosphorylase showed partial loss in the surface mesothelium by immunohistochemistry in three cases. Invasive malignant mesothelioma developed in seven patients with time between biopsy and invasive disease from 12 to 92 (median 60) months. Invasive mesothelioma has not developed in the other three patients at 12, 57, and 120 months, but the latter patient, who has pleural plaques, still has repeated pleural effusions, probably representing a so-called "benign asbestos effusion." We conclude that mesothelioma in situ, as diagnosed using the criteria outlined above, is associated with a high risk of developing invasive mesothelioma, but typically over a relatively protracted time, so that curable interventions maybe possible.

Role of matrix metalloproteinases in tumour invasion: immunohistochemistry of peritoneum from peritoneal carcinomatosis.

Colorectal cancer is one of the most common forms of cancer. Spread of tumour to the peritoneal cavity may lead to seeding of cancer cells that adhere to and invade the peritoneal membrane causing peritoneal carcinomatosis. Matrix metalloproteinases (MMPs) play an essential role in cancer cell invasion and dissemination. The aim of this study was to evaluate the morphology and presence of matrix metalloproteinases in peritoneal carcinomatosis. Biopsy samples of the parietal peritoneum were taken from patients undergoing cytoreductive surgery for peritoneal carcinomatosis. The samples were fixed in formalin, dehydrated and embedded in paraffin prior to cutting into 4-µm slices. Staining with haematoxylin/eosin was used for morphology studies, and MMP-1, MMP-2 and TIMP-1 levels were evaluated using immunohistochemistry and light microscopy. The microscopically tumour-free areas of the peritoneal membrane were thin compared to the peripheral invasion zone and the areas invaded by tumour. Peritoneum invaded by tumour was richly vascularised and contained inflammatory cells. MMP-1 was expressed in tumour-free peritoneum and in the invasion zone between tumour and peritoneal tissue, but not in tumour-invaded areas. MMP-2 and TIMP-1 were mostly expressed in the proximity of blood vessels and inflammatory cells in tumour-invaded areas, but was not seen in tumour-free areas. MMPs play an important role in the process of cancer cell invasion of the peritoneum in peritoneal carcinomatosis. The peripheral zone of the tumour appears to be of importance for tumour invasion.

G9A promotes gastric cancer metastasis by upregulating ITGB3 in a SET domain-independent manner.

Tumor metastasis is the leading cause of death in patients with advanced gastric cancer (GC). Limited therapeutic regimens are available for this condition, which is associated with a poor prognosis, and the mechanisms underlying tumor metastasis remain unclear. In the present study, increased histone methyltransferase G9A expression in GC tissues correlated with advanced stage and shorter overall survival, and in vitro and in vivo experiments revealed that G9A promoted tumor invasion and metastasis. Moreover, we observed that Reg IV induced G9A via the p-ERK/p-SP1 pathway. SP1 directly binds the G9A promoter and enhances G9A expression, and upregulated G9A then forms a transcriptional activator complex with P300 and GR, thereby promoting ITGB3 expression induced by dexamethasone (DEX) and contributing to GC metastasis. However, the G9A-mediated increase in ITGB3 expression was not dependent on the SET domain and methyltransferase activity of G9A. This study demonstrates that G9A is an independent prognostic marker and promotes metastasis in GC, thus suggesting that it may be a tumor biomarker and potential therapeutic target in GC.

ASPP2 suppresses invasion and TGF-ß1-induced epithelial-mesenchymal transition by inhibiting Smad7 degradation mediated by E3 ubiquitin ligase ITCH in gastric cancer.

ASPP2 regulates cell polarity and cell-cell adhesion by binding to, and co-localizing with PAR3 at tight junctions. Here we show a novel role of ASPP2 in suppressing gastric cancer (GC) invasiveness. Immunoprecipitation and immunofluorescence analyses showed that ASPP2 promoted the recruitment of PAR3 to cell-cell junctions in GC cells. Diminished expression of ASPP2 and loss of junctional PAR3 localization were significantly associated with diffuse-type histology, deeper invasion depth, positive peritoneal dissemination and worse prognosis in primary GC. ASPP2 suppressed migration and invasion of GC cells in vitro and peritoneal dissemination of GC cells in vivo in a mouse model. ASPP2 suppressed epithelial-mesenchymal transition (EMT) induced by TGF-ß1-Smad2/3 signaling in GC cells through suppression of the degradation of Smad7, a negative regulator of TGF-ß1-Smad2/3 signaling, by interacting with the E3 ubiquitin ligase ITCH. In conclusion, ASPP2 suppresses invasion, peritoneal dissemination and TGF-ß1-induced EMT by inhibiting Smad7 degradation mediated by ITCH.

Carbonic anhydrase II: a novel biomarker for pseudomyxoma peritonei.

Altered expression of carbonic anhydrase (CA) II is associated with human carcinogenesis. We analysed CA II protein expression in 89 patients with pseudomyxoma peritonei (PMP) and correlated its association against survival. We determined the expression of CA II by immunohistochemistry and then scored the staining results. The correlations of CA II expression with Peritoneal Cancer Index (PCI) and tumour grade were examined. The effect of CA II and tumour grade on survival was investigated. Positive CA II expression was found in 58 patients (65%) and absent in 31 patients (35%). High-grade (HG) morphology was associated with a loss of CA II expression (p = 0.048). The mean CA II immunostaining intensity score was 1.00 ± 1.1 (median 1, range 0-3) for HG morphology and 1.54 ± 1.1 (median 2, range 0-3) for low-grade (LG) morphology. The 5-year overall survival (OS) for those patients with CA II expression was 80% and 59% for those without (p < 0.001). The 5-year OS rates for those patients with HG morphology and positive CA II expression was 72% and 31% for those with negative CA II expression (p = 0.044). This study suggests that the expression of CA II acts as independent prognostic biomarker for survival in PMP.

Therapeutic Cell-Cycle-Decoy Efficacy of a Telomerase-Dependent Adenovirus in an Orthotopic Model of Chemotherapy-Resistant Human Stomach Carcinomatosis Peritonitis Visualized With FUCCI Imaging.

We have established an orthotopic nude-mouse model of gastric cancer carcinomatosis peritonitis, a recalcitrant disease in human patients. Human MKN45 poorly-differentiated human gastric cancer cells developed carcinomatosis peritonitis upon orthotopic transplantation in nude mice. The MKN45 cells expressed the fluorescent ubiquitination-based cell cycle indicator (FUCCI) that color codes the phases of the cell cycle. The intra-peritoneal tumors and ascites contained mostly quiescent G1 /Go cancer cells visualized as red by FUCCI imaging. Cisplatinum (CDDP) treatment did not reduce bloody ascites, and larger tumors formed in the peritoneal cavity after CDDP treatment in an early-stage carcinomatosis peritonitis orthotopic mouse model. Paclitaxel-treated mice had reduced ascites, but also had large tumor masses in the peritonium after treatment with cancer cells mostly in G0 /G1 , visualized by FUCCI red. In contrast, OBP-301 telomerase-dependent adenovirus-treated mice had no ascites and only small tumor nodules consisting of cancer cells mostly in S/G2 phases in the early-stage carcinomatosis peritonitis model, visualized by FUCCI green. Furthermore, OBP-301 significantly reduced the size of tumors (P < 0.01) and ascites even in a late-stage carcinomatosis peritonitis model. These results suggest that quiescent peritoneally-disseminated gastric cancer cells are resistant to conventional chemotherapy, but OBP-301 significantly reduced the weight of the tumors and increased survival, suggesting clinical potential. J. Cell. Biochem. 118: 3635-3642, 2017. © 2016 Wiley Periodicals, Inc.

MiRNA-3978 regulates peritoneal gastric cancer metastasis by targeting legumain.

Gastric cancer incidence and mortality are among the highest in China, with majority of the mortality related to peritoneal metastasis of gastric cancer. Treatment is limited to radical resection, which is impeded by incidence of metastasis at time of initial diagnosis, thus making it imperative to identify diagnostic and prognostic biomarkers. Legumain, a lysosomal cysteine endopeptidase of the asparaginyl endopeptidase family, has been shown to be overexpressed in patients with metastatic gastric cancer disease and its expression was positively correlated to both disease progression and outcome. However, the mechanism of legumain expression is currently unknown. Legumain overexpression was found to occur at the level of post transcriptional gene regulation. In situ prediction algorithms identified legumain as a putative target of miR-3978. MiR-3978 was significantly decreased in peritoneal metastatic tissue specimens and in MKN45 cells that mimic peritoneal metastasis features. Reporter assays using LGMN (encoding legumain) 3' untranslated region (UTR) showed that miR-3978 interacted with the wild-type but not miR-3978-seed mutant. Ectopic expression of miR-3978 mimic in the MKN45 cell line significantly decreased proliferation and suppressed in vitro migration and invasion. The miR-3978 mimic inhibited gastric carcinoma and metastatic progression in a mice model by regulating legumain protein expression. Inverse correlation of LGMN mRNA and miR-3978 levels in 20 gastric patients at different stages of metastatic disease confirmed the same. Cumulatively, our results indicate that loss of miR-3978 leads to increased expression of legumain, which indicates that miR-3978might be a biomarker for peritoneal metastasis in patients with gastric cancer.

Host sphingosine kinase 1 worsens pancreatic cancer peritoneal carcinomatosis.

BACKGROUND: There are no effective treatments for pancreatic cancer peritoneal carcinomatosis (PC) or cancer dissemination in abdominal cavity. Sphingosine-1-phosphate (S1P), a bioactive lipid mediator produced by sphingosine kinases (SphK1 and SphK2), plays critical roles in cancer progression. We reported that SphK1, but not SphK2, is responsible for S1P export from breast cancer cells and recently discovered that S1P is linked to inflammation and cancer in colitis-associated cancer progression. Given the fact that inflammation is known to be essential for the establishment and progression of PC, we hypothesized that SphK1 in the host animals is involved in progression of pancreatic cancer PC. METHODS: Murine pancreatic adenocarcinoma panc02-luc cells were intraperitoneally injected into wildtype or SphK1 knockout (KO) mice to generate a syngeneic PC model. Cell proliferation and apoptosis were determined by Ki67 and TUNEL staining, respectively. RESULTS: All the animals developed panc02-luc PC. SphK1 KO mice developed significantly less tumor burden, less total tumor weight, and fewer number of PC nodules at 14 d after implantation. Histologically, less inflammatory cell infiltration and less cancer cell proliferation were observed in the tumors. There was no difference in apoptosis. CONCLUSIONS: Our results raise an intriguing possibility that S1P generated by SphK1 in the host promotes pancreatic cancer PC progression by stimulation of proliferation of cancer cells.

Integrated Molecular Profiling of Human Gastric Cancer Identifies DDR2 as a Potential Regulator of Peritoneal Dissemination.

Peritoneal dissemination is the most frequent, incurable metastasis occurring in patients with advanced gastric cancer (GC). However, molecular mechanisms driving peritoneal dissemination still remain poorly understood. Here, we aimed to provide novel insights into the molecular mechanisms that drive the peritoneal dissemination of GC. We performed combined expression analysis with in vivo-selected metastatic cell lines and samples from 200 GC patients to identify driver genes of peritoneal dissemination. The driver-gene functions associated with GC dissemination were examined using a mouse xenograft model. We identified a peritoneal dissemination-associated expression signature, whose profile correlated with those of genes related to development, focal adhesion, and the extracellular matrix. Among the genes comprising the expression signature, we identified that discoidin-domain receptor 2 (DDR2) as a potential regulator of peritoneal dissemination. The DDR2 was upregulated by the loss of DNA methylation and that DDR2 knockdown reduced peritoneal metastasis in a xenograft model. Dasatinib, an inhibitor of the DDR2 signaling pathway, effectively suppressed peritoneal dissemination. DDR2 was identified as a driver gene for GC dissemination from the combined expression signature and can potentially serve as a novel therapeutic target for inhibiting GC peritoneal dissemination.

Transketolase is upregulated in metastatic peritoneal implants and promotes ovarian cancer cell proliferation.

Ovarian cancer, the most lethal gynaecological cancer, is characterised by the shedding of epithelial cells from the ovarian surface, followed by metastasis and implantation onto the peritoneal surfaces of abdominal organs. Our proteomic studies investigating the interactions between peritoneal (LP-9) and ovarian cancer (OVCAR-5) cells found transketolase (TKT) to be regulated in the co-culture system. This study characterized TKT expression in advanced stage (III/IV) serous ovarian cancers (n = 125 primary and n = 54 peritoneal metastases), normal ovaries (n = 6) and benign serous cystadenomas (n = 10) by immunohistochemistry. In addition, we also evaluated the function of TKT in ovarian cancer cells in vitro. Nuclear TKT was present in all primary serous ovarian cancer tissues examined (median 82.0 %, range 16.5-100 %) and was significantly increased in peritoneal metastases compared with matching primary cancers (P = 0.01, Wilcoxon Rank test). Kaplan-Meier survival and Cox regression analyses showed that high nuclear TKT positivity in peritoneal metastases (>94 %) was significantly associated with reduced overall survival (P = 0.006) and a 2.8 fold increased risk of ovarian cancer death (95 % CI 1.29-5.90, P = 0.009). Knockdown of TKT by siRNAs significantly reduced SKOV-3 cell proliferation but had no effect on their motility or invasion. Oxythiamine, an inhibitor of TKT activity, significantly inhibited the proliferation of four ovarian cancer cell lines (OV-90, SKOV-3, OVCAR-3 and OVCAR-5) and primary serous ovarian cancer cells isolated from patient ascites. In conclusion, these findings indicate that TKT plays an important role in the proliferation of metastatic ovarian cancer cells and could be used as novel therapeutic target for advanced disease.

Decreased peritoneal ovarian cancer growth in mice lacking expression of lipid phosphate phosphohydrolase 1.

Lysophosphatidic acid (LPA) is a bioactive lipid that enhances ovarian cancer cell proliferation, migration and invasion in vitro and stimulates peritoneal metastasis in vivo. LPA is generated through the action of autotaxin or phospholipases, and degradation begins with lipid phosphate phosphohydrolase (LPP)-dependent removal of the phosphate. While the effects of LPA on ovarian cancer progression are clear, the effects of LPA metabolism within the tumor microenvironment on peritoneal metastasis have not been reported. We examined the contribution of lipid phosphatase activity to ovarian cancer peritoneal metastasis using mice deficient in LPP1 expression. Homozygous deletion of LPP1 (LPP1 KO) results in elevated levels and decreased turnover of LPA in vivo. Within 2 weeks of intraperitoneal injection of syngeneic mouse ovarian cancer cells, we observed enhanced tumor seeding in the LPP1 KO mice compared to wild type. However, tumor growth plateaued in the LPP1 KO mice by 3 weeks while tumors continued to grow in wild type mice. The decreased tumor burden was accompanied by increased apoptosis and no change in proliferation or angiogenesis. Tumor growth was restored and apoptosis reversed with exogenous administration of LPA. Together, these observations demonstrate that the elevated levels of LPA per se in LPP1 KO mice do not inhibit tumor growth. Rather, the data support the notion that either elevated LPA concentration or altered LPA metabolism affects other growth-promoting contributions of the tumor microenvironment.

Cyclin-Dependent Kinase Activity Correlates with the Prognosis of Patients Who Have Gastrointestinal Stromal Tumors.

BACKGROUND: The estimation of recurrence risk remains a critical issue in relation to gastrointestinal stromal tumors (GISTs) treated with adjuvant therapy. The accuracy of the commonly used risk stratifications is not always adequate. METHODS: For this study, data were prospectively collected from 68 patients with GISTs who underwent R0 surgery between 2004 and 2009. The results from this analysis cohort were evaluated using the data obtained from an additional 40 patients in the validation cohort. Cyclin-dependent kinase 1 (CDK1)- and CDK2-specific activities were measured using a non-RI kinase assay system. RESULTS: The specific activities of CDK1 and CDK2, but not their expression, significantly correlated with recurrence. The specific activities of both CDK1 and CDK2 were independently correlated with mitosis and significantly correlated with recurrence-free survival (RFS). In the multivariate analysis, CDK2-specific activity (P = 0.0006), tumor size (P = 0.0347), and KIT deletion mutations (P = 0.0006) were significantly correlated with RFS in the analysis cohort. In the validation cohort, CDK2-specific activity (P = 0.0368) was identified as an independent prognostic factor for tumor recurrences with tumor location (P = 0.0442). CONCLUSION: The results suggest that the specific activities of CDK1 and CDK2 may reflect the proliferative activity of GISTs and that CDK2-specific activity is a good prognostic factor predicting recurrence after macroscopic complete resection of GISTs.

The C3G/Rap1 pathway promotes secretion of MMP-2 and MMP-9 and is involved in serous ovarian cancer metastasis.

Complete resection is pivotal to improve survival to epithelial ovarian cancer (EOC). Crk SH3-domain-binding guanine nucleotide-releasing factor (C3G) is involved in multiple signaling pathways and it has opposite roles in different cancers. The present study aimed to identify C3G expression in ovarian tissue samples from patients with EOC and to explore its association with tumor grade. Eighty-seven archival paraffin-embedded, formalin-fixed, ovarian cancer tissues with serous histology were stained for C3G by immunohistochemistry. To evaluate the contribution of C3G to Rap1 activity, 36 patients with serous ovarian cancer (SOC) were investigated. Additionally, C3G was knocked down in SKOV3 and HEY cells. C3G regulated Rap1 activity and high Rap1 activity was correlated with poor differentiation, advanced FIGO stage, and unsuccessful cytoreductive surgery of SOC. Knockdown of C3G suppressed cell invasion, intravasation and extravasation, and reduced Rap1 activity and secretion of matrix metalloproteinase (MMP)-2 and MMP-9. C3G-mediated activation of Rap1 could direct the tumor pattern of human SOC by promoting the secretion of MMP-2 and MMP-9. These results suggest that C3G is involved in the metastatic spread of EOC.

Rapamycin-enhanced mitomycin C-induced apoptotic death is mediated through the S6K1-Bad-Bak pathway in peritoneal carcinomatosis.

Peritoneal carcinomatosis (PC) is the most common secondary cancerous disease, and more effective novel regimens are needed. In this study, we identified a novel combination treatment for PC, chemotherapeutic agent mitomycin C in combination with mTOR (mammalian target of rapamycin) inhibitor rapamycin. We observed that the combination of mitomycin C and rapamycin induced synergistic cytotoxicity and apoptosis, which was mediated through an increase in caspase activation. The combination of mitomycin C and rapamycin inactivated p70 S6 ribosomal kinase (S6K1) and dephosphorylated Bad, leading to dissociation of Bcl-xL from Bak, which resulted in Bak oligomerization, mitochondria dysfunction and cytochrome c release. PF-4708671, a S6K1-specific inhibitor, enhanced the combination treatment-induced apoptosis, whereas S6K1 E389 DeltaCT-HA (S6K1 active form) dramatically decreased the induction of apoptosis. In addition, the combination treatment significantly inhibited LS174T intraperitoneal tumor growth in vivo. This study provides a preclinical rationale for apoptosis induction linked with the mTOR pathway through a combination of chemotherapeutic agents and mTOR inhibitor, and will support this combinatorial strategy to PC patients.

Phase II study of MLN8237 (alisertib), an investigational Aurora A kinase inhibitor, in patients with platinum-resistant or -refractory epithelial ovarian, fallopian tube, or primary peritoneal carcinoma.

OBJECTIVES: Aurora A kinase (AAK), a key mitotic regulator, is implicated in the pathogenesis of several tumors, including ovarian cancer. This single-arm phase II study assessed single-agent efficacy and safety of the investigational AAK inhibitor MLN8237 (alisertib), in patients with platinum-refractory or -resistant epithelial ovarian, fallopian tube, or primary peritoneal carcinoma. METHODS: Adult women with malignant, platinum-treated disease received MLN8237 50mg orally twice daily for 7 days plus 14 days' rest (21-day cycles). The primary endpoint was combined objective tumor response rate per Response Evaluation Criteria in Solid Tumors (RECIST) and/or CA-125 criteria. Secondary endpoints included response duration, clinical benefit rate, progression-free survival (PFS), time-to-progression (TTP), and safety. RESULTS: Thirty-one patients with epithelial ovarian (n=25), primary peritoneal (n=5), and fallopian tube carcinomas (n=1) were enrolled. Responses of 6.9-11.1 month duration were observed in 3 (10%) patients with platinum-resistant ovarian cancer. Sixteen (52%) patients achieved stable disease with a mean duration of response of 2.86 months and which was durable for ≥3 months in 6 (19%). Median PFS and TTP were 1.9 months. Most common drug-related grade≥3 adverse events were neutropenia (42%), leukopenia (23%), stomatitis, and thrombocytopenia (each 19%); 6% reported febrile neutropenia. CONCLUSIONS: These data suggest that MLN8237 has modest single-agent antitumor activity and may produce responses and durable disease control in some patients with platinum-resistant ovarian cancer. MLN8237 is currently undergoing evaluation in a phase I/II trial with paclitaxel in recurrent ovarian cancer.

Patients with peritoneal mesothelioma lack epidermal growth factor receptor tyrosine kinase mutations that would make them sensitive to tyrosine kinase inhibitors.

The epidermal growth factor receptor (EGFR) is a promising target for cancer therapy. The presence of certain somatic mutations in the tyrosine kinase (TK) domain of the EGFR gene is associated with clinical response to TK inhibitors (TKI) in patients with lung adenocarcinoma. In this study we evaluated the status of somatic mutations in the entire TK domain of the EGFR gene by direct sequencing using early passage peritoneal mesothelioma cells, established cell lines as well as 33 peritoneal mesothelioma tumor samples. No novel mutations were found in the cell lines. Sequence analysis of the EGFR TK domain revealed the presence of a silent polymorphism (c.2607G → A, Q787Q) at exon 20 of both peritoneal mesothelioma cell lines as well as tumor specimens. The frequency of genotypes AA and GA was 42.8 and 57.2% in the cell lines and 33.3 and 57.6% in tumor specimens, respectively. The TKI erlotinib showed an IC50 in the range of 10-50 µM in five out of the seven cell lines with a GA genotype while all five cell lines with the AA genotype had an IC50 >50 µM. Of the 33 peritoneal mesothelioma tumor samples analyzed none had an EGFR TKI sensitizing mutation and only one specimen showed an earlier reported somatic mutation at codon 850 in exon 21 of the EGFR gene. Our data show that patients with peritoneal mesothelioma do not harbor somatic mutations in the EGFR TK domain that would make them sensitive to EGFR TKI.