The title of this article is taken from a 1971 publication by Yoshio Masui and Clement Markert in which they describe the discoveries of the meiotic regulatory activities maturation promoting factor ...and cytostatic factor. Here we review the experiments that led to these discoveries and discuss their relation to our current knowledge of the biochemistry of oocyte maturation.
Abstract
Mitogen activated protein kinase kinase 1/2 (MEK1/2) inhibitors have failed to demonstrate a sustained clinical benefit for the treatment of melanoma or other MEK1/2 dependent cancers. We ...hypothesize combined treatment with inhibitors of MEK1/2 plus another cancer pathway would provide a more durable tumor response for MEK1/2 driven cancers. To test this we examined in vitro synergy between MEK1/2 inhibitor PD0325901 and inhibitors to eleven common cancer pathways using MEK1/2-driven melanoma cell lines and canine hemangiosarcoma cell isolates. Combination indices (CI) were calculated following the methods of Chou and Talalay (Chou and Talalay, 1984). Of the combinations tested, tyrosine kinase receptor inhibitors sorafenib and dasatinib, and the dual PI3 kinase and mTOR inhibitor rapamycin showed synergy (CI<0.7) with PD0325901. To validate these results we subsequently tested synergy for PD0325901 plus sorafenib in vivo using mouse xenograft models for melanoma and canine angiosarcoma. We conclude dual inhibition of MEK1/2 and receptor tyrosine kinases or mTOR signaling are useful strategies to treat MEK1/2 dependent cancers.
Citation Format: Nicholas John Andersen, Elissa Boguslawski, Roe Froman, Nicholas Duesbery. Improved response of mitogen activated protein kinase kinase 1/2-dependent tumors using combination drug therapy. abstract. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3270. doi:10.1158/1538-7445.AM2013-3270
Anthrax is caused by the gram-positive bacterium Bacillus anthracis. The pathogenesis of this disease is dependent on the presence of two binary toxins, edema toxin (EdTx) and lethal toxin (LeTx). ...LeTx, the major virulence factor contributing to anthrax, contains the effector moiety lethal factor (LF), a zinc-dependent metalloprotease specific for targeting mitogen-activated protein kinase kinases. This review will focus on the protease-specific activity and function of LF, and will include a discussion on the implications and consequences of this activity, both in terms of anthrax disease, and how this activity can be exploited to gain insight into other pathologic conditions.
Abstract
Angiosarcoma is a rare endothelial derived soft-tissue tumor with an estimated incidence of 0.2/100,000 persons/year. Current treatment regimes include surgical resection followed by ...chemotherapy. Even after treatment, reoccurrence is likely and usually fatal. The canine equivalent of angiosarcoma, hemangiosarcoma (HSA), is a relatively common canine endothelial neoplasm with an overall incidence of 24/100,000. In addition, canine HSA is more prevalent in specific breeds suggesting a genetic component. Similar to human angiosarcoma, HSA present as two basic forms: visceral (spleen or cardiac) and dermal. Furthermore, canine HSA occur spontaneously making canine HSA a relevant model system to study human angiosarcoma. Interestingly, MEK/MAPK signaling cascade is activated in Kaposi's Sarcoma, another human endothelial derived cancer. We hypothesize that the MEK/MAPK signaling cascade is vital for HSA and angiosarcoma growth and survival. We performed expression analysis supplemented by small molecule inhibitor studies utilizing canine primary cell isolates derived from visceral and dermal HSA. MAPK pathway expression signatures are elevated in HSA primary isolates compared to proliferating endothelial cells. Consistent with mRNA expression studies, ERK2 is constitutively phosphorylated in serum starved conditions. In addition, HSA cell viability is reduced by the MEK1/2 inhibitor CI-1040 compared to isolated canine endothelial cells. Other inhibitors targeting tyrosine kinase receptors (Sorafenib, EGFR Inhibitor, and SU11652) also decrease HSA cell viability. We conclude a network of tyrosine kinase receptors constitutively activate the MEK/MAPK signaling pathway in HSA. This work provides insights in the etiology and therapeutic potential for targeting both canine HSA and angiosarcoma.
Citation Format: {Authors}. {Abstract title} abstract. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2929. doi:10.1158/1538-7445.AM2011-2929
Purpose: In this study, we tested the hypothesis that inhibition of mitogen-activated protein kinase kinases (MKK) inhibits tumor growth by acting on angiogenic signaling and by extension may form ...the basis of an effective strategy for treatment of Kaposi's sarcoma. Experimental Design: Murine endothelial cells expressing the human herpes virus 8 G protein–coupled receptor (vGPCR-SVEC) were treated with anthrax lethal toxin (LeTx). LeTx is a binary toxin ordinarily secreted by Bacillus anthracis and is composed of two proteins: protective antigen (the binding moiety) and lethal factor (the active moiety). Lethal factor is a protease that cleaves and inactivates MKKs. Results: In vitro, treatment of vGPCR-SVEC with LeTx inhibited MKK signaling, moderately inhibited cell proliferation, and blocked the ability of these cells to form colonies in soft agar. Treatment with LeTx also blocked the ability of these cells to release several angioproliferative cytokines, notably vascular endothelial growth factor (VEGF). In contrast, inhibition of mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 with U0126 caused a substantial inhibition of proliferation but only modestly inhibited VEGF release. In xenograft models, i.v. injection of LeTx caused reduced tumor growth characterized immunohistochemically by inhibition of MKK signaling, decreased rates of proliferation, and reduced levels of VEGF and VEGF receptor 2, with a corresponding decrease in vascular density. Conclusions: These data support a role for MKK signaling in tumor growth and vascularization and are consistent with the hypothesis that inhibition of MKK signaling by LeTx or a similar agent may be an effective strategy for the treatment of Kaposi's sarcoma as well as other vascular tumors.
How Anthrax Kills Hanna, Philip; Duesbery, Nicholas; Woude, George Vande ...
Science (American Association for the Advancement of Science),
06/1998, Letnik:
280, Številka:
5370
Journal Article
Xenopus oocytes induced to mature by progesterone undergo a rapid influx followed by an efflux of Ca$\sp{2+},$ thus transiently increasing in the Ca$\sp{2+}$-content. Chelation of intracellular ...Ca$\sp{2+}$ inhibited progesterone-induced maturation. Ca$\sp{2+}$-Buffers with a mid-range Kd ($\sim$1.5 $\mu$M) were most effective in inhibiting maturation whereas buffers with a Kd above or below this value were less effective. These observations indicate that, intracellular Ca$\sp{2+},$ probably in the form of a localized release, is required for progesterone-induced oocyte maturation. However, Ca$\sp{2+}$-release alone was insufficient to induce maturation. Taxol-induced microtubule polymerization not only delayed progesterone-induced maturation but also completely inhibited it in combination with BAPTA-AM. Conversely, nocodazole-induced microtubule depolymerization in combination with ionophore A23187 not only accelerated progesterone-induced maturation, but also induced maturation in the absence of progesterone. The combined treatment of oocytes with nocodazole and Ca$\sp{2+}$-releasing agents induced their maturation in the absence of progesterone. In oocytes thus treated, the oocyte nucleus was displaced to the periphery of the oocyte and broke down. In contrast, when the GV was displaced to the cortex by a centrifugal force under conditions that would not cause microtubule depolymerization the oocyte nucleus did not break down when treated with Ca$\sp{2+}$-releasing agents. In vitro experiments indicated that microtubule polymerization decreased the sensitivity of oocyte microsomes to InsP$\sb3$-induced Ca$\sp{2+}$-release and that InsP$\sb3$-induced Ca$\sp{2+}$-release caused tyrosine phosphorylation of 42K MAP kinase, which was prevented by Ca$\sp{2+}$-chelation with BAPTA and by taxol, but not by nocodazole. In addition, it was observed that $\beta$-tubulin associated with ER-enriched membrane fractions at interphase but not at metaphase. This suggests that microtubules may regulate ER activity. Therefore, it is suggested that microtubule polymerization modifies InsP$\sb3$-induced Ca$\sp{2+}$-release, thereby inhibiting phosphorylation of MAP kinase and thus, Ca$\sp{2+}$-release and microtubule depolymerization synergistically promote maturation.
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