Publications by authors named "Joshua M Eichhorn"

Background: Pheochromocytoma is a neuroendocrine tumor, and its treatment is dependent on surgical resection. Due to the wide availability of cross-sectional imaging, pheochromocytomas are commonly seen as small tumors less than 10 cm in size and are mostly treated with minimally invasive surgery. Their concomitant presence with horseshoe kidney or other anatomical and vascular anomalies is rare.

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BH3 mimetic drugs may be useful to treat acute lymphoblastic leukemia (ALL) but the sensitivity of primary tumor cells has not been fully evaluated. Here, B-lineage ALL cell cultures derived from a set of primary tumors were studied with respect to sensitivity to the BH3 mimetics ABT-263 and ABT-199 and to Bcl-2 dependence and function. These ALL cells each expressed high levels of Bcl-2 and exhibited great sensitivity to ABT-263 and ABT-199, which induced rapid apoptotic cell death.

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Microtubule inhibitors are widely used in cancer chemotherapy. These drugs characteristically induce mitotic arrest and cell death but the mechanisms linking the two are not firmly established. One of the problems is that cancer cells vary widely in their sensitivity to these agents, and thus comparison of data from different systems is difficult.

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Article Synopsis
  • The Bcl-2 family proteins are key regulators of intrinsic apoptosis, with anti-apoptotic members like Mcl-1, Bcl-2, and Bcl-xL displaying functional redundancy, which was mainly studied through pharmacological inhibitors.
  • Using a combined knockdown and overexpression approach, researchers found that HeLa cells rely heavily on Mcl-1 for survival, and when this protein is absent, Bcl-xL can compensate by managing pro-apoptotic proteins Bak and Bim.
  • This study, which reveals the interconnectedness of these proteins and highlights a novel method for examining their roles, shows that loss of Mcl-1 can lead to cell death, which can be mitigated by silencing a specific pro-ap
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This study examined the molecular mechanism of action of anti-mitotic drugs. The hypothesis was tested that death in mitosis occurs through sustained mitotic arrest with robust Cdk1 signaling causing complete phosphorylation of Mcl-1 and Bcl-xL, and conversely, that mitotic slippage is associated with incomplete phosphorylation of Mcl-1/Bcl-xL. The results, obtained from studying six different cancer cell lines, strongly support the hypothesis and identify for the first time a unique molecular signature for mitotic death.

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The prevailing model suggests that cell fate after mitotic arrest depends on two independent and competing networks that control cyclin B1 degradation and the generation of death signals. However, recent evidence for Cdk1/cyclin B1-mediated phosphorylation and inactivation of antiapoptotic Bcl-2 proteins suggests the existence of significant cross-talk and interdependence between these pathways. Further, the nature of the mitotic death signals has remained elusive.

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