Ogilvie's syndrome-is there a cutoff diameter to proceed with upfront surgery?

PURPOSE: Although Ogilvie's syndrome was first described about 70 years ago, its etiology and pathogenesis are still not fully understood. But more importantly, it is also not clear when to approach which therapeutic strategy. METHODS: Patients who were diagnosed with Ogilvie's syndrome at our institution in a 17-year time period (2002-2019) were included and retrospectively evaluated regarding different therapeutical strategies: conservative, endoscopic, or surgical. RESULTS: The study included 71 patients with 21 patients undergoing conservative therapy, 25 patients undergoing endoscopic therapy, and 25 patients undergoing surgery. However, 38% of patients (n = 8) who were primarily addressed for conservative management failed and had to undergo endoscopy or even surgery. Similarly, 8 patients (32%) with primarily endoscopic treatment had to proceed for surgery. In logistic regression analysis, only a colon diameter ≥ 11 cm (p = 0.01) could predict a lack of therapeutic success by endoscopic treatment. Ninety-day mortality and overall survival were comparable between the groups. CONCLUSION: As conservative and endoscopic management fail in about one-third of patients, a cutoff diameter ≥ 11 cm may be an adequate parameter to evaluate surgical therapy.

Role of mammalian target of rapamycin complex 2 in primary and secondary liver cancer.

The mammalian target of rapamycin (mTOR) acts in two structurally and functionally distinct protein complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). Upon deregulation, activated mTOR signaling is associated with multiple processes involved in tumor growth and metastasis. Compared with mTORC1, much less is known about mTORC2 in cancer, mainly because of the unavailability of a selective inhibitor. However, existing data suggest that mTORC2 with its two distinct subunits Rictor and mSin1 might play a more important role than assumed so far. It is one of the key effectors of the PI3K/AKT/mTOR pathway and stimulates cell growth, cell survival, metabolism, and cytoskeletal organization. It is not only implicated in tumor progression, metastasis, and the tumor microenvironment but also in resistance to therapy. Rictor, the central subunit of mTORC2, was found to be upregulated in different kinds of cancers and is associated with advanced tumor stages and a bad prognosis. Moreover, AKT, the main downstream regulator of mTORC2/Rictor, is one of the most highly activated proteins in cancer. Primary and secondary liver cancer are major problems for current cancer therapy due to the lack of specific medical treatment, emphasizing the need for further therapeutic options. This review, therefore, summarizes the role of mTORC2/Rictor in cancer, with special focus on primary liver cancer but also on liver metastases.

Dual Inhibition of mTORC1/2 Reduces Migration of Cholangiocarcinoma Cells by Regulation of Matrixmetalloproteinases.

Cholangiocarcinoma (CCA) is a rare but highly aggressive tumor entity for which systemic therapies only showed limited efficacy so far. As OSI-027-a dual kinase inhibitor targeting both mTOR complexes, mTORC1 and mTORC2 - showed improved anti-cancer effects, we sought to evaluate its impact on the migratory and metastatic capacity of CCA cells in vitro. We found that treatment with OSI-027 leads to reduced cell mobility and migration as well as a reduced surviving fraction in colony-forming ability. While neither cell viability nor proliferation rate was affected, OSI-027 decreased the expression of MMP2 and MMP9. Moreover, survival as well as anti-apoptotic signaling was impaired upon the use of OSI-027 as determined by AKT and MAPK blotting. Dual targeting of mTORC1/2 might therefore be a viable option for anti-neoplastic therapy in CCA.

Pharmacological Inhibition of mTORC2 Reduces Migration and Metastasis in Melanoma.

Despite recent advances in therapy, liver metastasis from melanoma is still associated with poor prognosis. Although targeting the mTOR signaling pathway exerts potent anti-tumor activity, little is known about specific mTORC2 inhibition regarding liver metastasis. Using the novel mTORC2 specific inhibitor JR-AB2-011, we show significantly reduced migration and invasion capacity by impaired activation of MMP2 in melanoma cells. In addition, blockade of mTORC2 induces cell death by non-apoptotic pathways and reduces tumor cell proliferation rate dose-dependently. Furthermore, a significant reduction of liver metastasis was detected in a syngeneic murine metastasis model upon therapy with JR-AB2-011 as determined by in vivo imaging and necropsy. Hence, our study for the first time highlights the impact of the pharmacological blockade of mTORC2 as a potent novel anti-cancer approach for liver metastasis from melanoma.

Cytopathological Heterogeneity of Circulating Tumor Cells in Non-metastatic Esophageal Adenocarcinoma.

BACKGROUND/AIM: The presence of circulating tumor cells (CTC) has been reported to have an impact on prognosis in different tumor entities. Little is known about CTC morphology and heterogeneity. PATIENTS AND METHODS: In a multicenter setting, pre-therapeutic peripheral blood specimens were drawn from patients with non-metastatic esophageal adenocarcinoma (EAC). CTCs were captured by size-based filtration (ScreenCell®), subsequently Giemsa-stained and evaluated by two trained readers. The isolated cells were categorized in groups based on morphologic criteria. RESULTS: Small and large single CTCs, as well as CTC-clusters, were observed in 69.2% (n=81) of the 117 specimens; small CTCs were observed most frequently (59%; n=69), followed by large CTCs (40%; n=47) and circulating cancer-associated macrophage-like cells (CAMLs; 34.2%, n=40). Clusters were rather rare (12%; n=14). CTC/CAML were heterogeneous in the cohort, but also within one specimen. Neither the presence of the CTC subtypes/CAMLs nor the exact cell count were associated with the primary clinical TNM stage. CONCLUSION: Morphologically heterogenic CTCs and CAMLs are present in patients with non-metastatic, non-pretreated EAC.

Metabolic Adaptation during nab-Paclitaxel Resistance in Pancreatic Cancer Cell Lines.

Pancreatic ductal adenocarcinoma (PDAC) correlates with high mortality and is about to become one of the major reasons for cancer-related mortality in the next decades. One reason for that high mortality is the limited availability of effective chemotherapy as well as the intrinsic or acquired resistance against it. Here, we report the impact of nab-paclitaxel on the cellular metabolome of PDAC cell lines. After establishment of nab-paclitaxel resistant cell lines, comparison of parental and resistant PDAC cell lines by metabolomics and biochemical assessments revealed altered metabolism, enhanced viability and reduced apoptosis. The results unveiled that acute nab-paclitaxel treatment affected primary metabolism to a minor extent. However, acquisition of resistance led to altered metabolites in both cell lines tested. Specifically, aspartic acid and carbamoyl-aspartic acid were differentially abundant, which might indicate an increased de novo pyrimidine synthesis. This pathway has already shown a similar behavior in other cancerous entities and thus might serve in the future as vulnerable target fighting resistance acquisition occurring in common malignancies.

Cyclooxygenase (COX) Inhibition by Acetyl Salicylic Acid (ASA) Enhances Antitumor Effects of Nitric Oxide in Glioblastoma In Vitro.

Glioblastoma multiforme (GBM) is the most aggressive brain tumor with a high recurrence rate and a median survival of about 16 months even with multimodal therapy. Novel experimental strategies against malignant gliomas include cyclooxygenase (COX) inhibition and nitric oxide (NO)-based therapies. Therapeutic doses of NO can be delivered to tumor cells by NO donors such as JS-K (O2-(2,4-dinitrophenyl)1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate) which releases NO upon enzymatic activation by glutathione S-transferase. COX-2 is frequently overexpressed in tumors and increases tumor invasiveness and angiogenesis. In this study, we show that pretreatment with acetyl salicylic acid (ASA) enhanced the cytotoxic antitumor effect of NO in vitro. Combination of low doses of JS-K and ASA revealed a dose-dependent synergistic increase of necrotic cell death under circumvention of classical apoptosis and alteration of the metabolic calcium level. These findings provide an opportunity to improve currently used therapeutic strategies in the treatment of gliomas with a well-established remedy.

Inhibition of mTORC2/RICTOR Impairs Melanoma Hepatic Metastasis.

Mammalian target of rapamycin complex 2 (mTORC2) with its pivotal component rapamycin-insensitive companion of mTOR (RICTOR) is the major regulator of AKT phosphorylation and is increasingly implicated in tumor growth and progression. In cutaneous melanoma, an extremely aggressive and highly metastatic disease, RICTOR overexpression is involved in tumor development and invasiveness. Therefore, we investigated the impact of RICTOR inhibition in melanoma cells in vitro and in vivo with special emphasis on hepatic metastasis. Moreover, our study focused on the interaction of tumor cells and hepatic stellate cells (HSC) which play a crucial role in the hepatic microenvironment. In silico analysis revealed increased RICTOR expression in melanoma cells and tissues and indicated higher expression in advanced melanoma stages and metastases. In vitro, transient RICTOR knock-down via siRNA caused a significant reduction of tumor cell motility. Using a syngeneic murine splenic injection model, a significant decrease in liver metastasis burden was detected in vivo. Moreover, stimulation of melanoma cells with conditioned medium (CM) from activated HSC or hepatocyte growth factor (HGF) led to a significant induction of AKT phosphorylation and tumor cell motility. Blocking of RICTOR expression in cancer cells diminished constitutive and HGF-induced AKT phosphorylation as well as cell motility. Interestingly, RICTOR blockade also led to an abrogation of CM-induced effects on AKT phosphorylation and motility in melanoma cells. In conclusion, these results provide first evidence for a critical role of mTORC2/RICTOR in melanoma liver metastasis via cancer cell/HSC interactions.

The nitric oxide donor JS-K sensitizes U87 glioma cells to repetitive irradiation.

As a potent radiosensitizer nitric oxide (NO) may be a putative adjuvant in the treatment of malignant gliomas which are known for their radio- and chemoresistance. The NO donor prodrug JS-K (O2-(2.4-dinitrophenyl) 1-[(4-ethoxycarbonyl) piperazin-1-yl] diazen-1-ium-1,2-diolate) allows cell-type specific intracellular NO release via enzymatic activation by glutathione-S-transferases overexpressed in glioblastoma multiforme. The cytotoxic and radiosensitizing efficacy of JS-K was assessed in U87 glioma cells in vitro focusing on cell proliferation, induction of DNA damage, and cell death. In vivo efficacy of JS-K and repetitive irradiation were investigated in an orthotopic U87 xenograft model in mice. For the first time, we could show that JS-K acts as a potent cytotoxic and radiosensitizing agent in U87 cells in vitro. This dose- and time-dependent effect is due to an enhanced induction of DNA double-strand breaks leading to mitotic catastrophe as the dominant form of cell death. However, this potent cytotoxic and radiosensitizing effect could not be confirmed in an intracranial U87 xenograft model, possibly due to insufficient delivery into the brain. Although NO donor treatment was well tolerated, neither a retardation of tumor growth nor an extended survival could be observed after JS-K and/or radiotherapy.

ATF3 reduces migration capacity by regulation of matrix metalloproteinases via NFκB and STAT3 inhibition in glioblastoma.

Glioblastoma is associated with poor survival and a high recurrence rate in patients due to inevitable uncontrolled infiltrative tumor growth. The elucidation of the molecular mechanisms may offer opportunities to prevent relapses. In this study we investigated the role of the activating transcription factor 3 (ATF3) in migration of GBM cells in vitro. RNA microarray revealed that gene expression of ATF3 is induced by a variety of chemotherapeutics and experimental agents such as the nitric oxide donor JS-K (O2-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate). We found NFκB and STAT3 to be downstream targets inhibited by overexpression of ATF3. We demonstrate that ATF3 is directly involved in the regulation of matrix metalloproteinase expression and activation. Overexpression of ATF3 therefore leads to a significantly reduced migration capacity and induction of tissue inhibitors of matrix metalloproteinases. Our study for the first time identifies ATF3 as a potential novel therapeutic target in glioblastoma.