Abstract-In atherosclerosis, circulating platelets interact with endothelial cells and monocytes, leading to cell activation and enhanced recruitment of leukocytes into the vascular wall. The invasion of monocytes is accompanied by overexpression of matrix metalloproteinases (MMPs), which are thought to promote atherosclerosis and trigger plaque rupture. Following interaction with itself, the extracellular matrix metalloproteinase inducer (EMMPRIN) induces MMP synthesis via a little-known intracellular pathway. Recently, we showed upregulation of EMMPRIN on monocytes during acute myocardial infarction. EMMPRIN also stimulates secretion of MMP-9 by monocytes and of MMP-2 by smooth muscle cells, indicating that it may be an important regulator of MMP activity. Expression of EMMPRIN on platelets has not been described until now. Here, we demonstrate that resting platelets show low surface expression of EMMPRIN, which is upregulated by various platelet stimulators (flow cytometry). EMMPRIN is located in the open canalicular system and in ␣ granules of platelets (according to electron microscopy and sucrose gradient ultracentrifugation). Platelet stimulation with recombinant EMMPRIN-Fc induced surface expression of CD40L and P-selectin (according to flow cytometry), suggesting that EMMPRIN-EMMPRIN interaction activates platelets. Coincubation of platelets with monocytes induced EMMPRIN-mediated nuclear factor B activation (according to Western blot) in monocytes with increased MMP-9 (zymography), interleukin-6, and tumor necrosis factor-␣ secretion (according to ELISA) by monocytes. In conclusion, EMMPRIN displays a new platelet receptor that is upregulated on activated platelets. Binding of EMMPRIN to platelets fosters platelet degranulation. Platelet-monocyte interactions via EMMPRIN stimulate nuclear factor B-driven inflammatory pathways in monocytes, such as MMP and cytokine induction. Thus, EMMPRIN may represent a novel target to diminish the burden of protease activity and inflammation in atherosclerosis. (Circ Res. 2008;102:302-309.)

Purpose: In gastrointestinal stromal tumor (GIST), there is no biomarker available that indicates success or failure of therapy. We hypothesized that tumor-specific v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (CKIT)- or platelet-derived growth factor receptor-α (PDGFRA)–mutant DNA fragments can be detected and quantified in plasma samples of patients with GIST. Experimental Design: We prospectively collected 291 plasma samples from 38 subjects with GIST harboring activating mutations of CKIT or PDGFRA detected in tumor tissue, irrespective of current disease status or treatment. We used allele-specific ligation PCR to detect mutant free circulating DNA (fcDNA). Results: We were able to detect fcDNA harboring the tumor mutation in 15 of 38 patients. Patients with active disease displayed significantly higher amounts of mutant fcDNA compared with patients in complete remission (CR). The amount of mutant fcDNA correlated with disease course. We observed repeated positive test results or an increase of mutant fcDNA in five patients with progressive disease or relapse. A decline of tumor fcDNA or conversion from positive to negative was seen in five patients responding to treatment. A negative to positive conversion was seen in two patients with relapse and one patient with progression. In two cases, we aimed to identify additional mutations and found four additional exchanges, including mutations not known from sequentially conducted tumor biopsies. Conclusions: Our results indicate that fcDNA harboring tumor-specific mutations in the plasma of patients with GIST can be used as tumor-specific biomarker. The detection of resistance mutations in plasma samples might allow earlier treatment changes and obviates the need for repeated tumor biopsies. Clin Cancer Res; 19(17); 4854–67. ©2013 AACR.

Apoptosis is a form of regulated cell death (RCD) that involves proteases of the caspase family. Pharmacological and genetic strategies that experimentally inhibit or delay apoptosis in mammalian systems have elucidated the key contribution of this process not only to (post-)embryonic development and adult tissue homeostasis, but also to the etiology of multiple human disorders. Consistent with this notion, while defects in the molecular machinery for apoptotic cell death impair organismal development and promote oncogenesis, the unwarranted activation of apoptosis promotes cell loss and tissue damage in the context of various neurological, cardiovascular, renal, hepatic, infectious, neoplastic and inflammatory conditions. Here, the Nomenclature Committee on Cell Death (NCCD) gathered to critically summarize an abundant pre-clinical literature mechanistically linking the core apoptotic apparatus to organismal homeostasis in the context of disease.

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Ferroptosis is a recently defined form of regulated cell death, which is biochemically and morphologically distinct from traditional forms of programmed cell death such as apoptosis or necrosis. It is driven by iron, reactive oxygen species, and phospholipids that are oxidatively damaged, ultimately resulting in mitochondrial damage and breakdown of membrane integrity. Numerous cellular signaling pathways and molecules are involved in the regulation of ferroptosis, including enzymes that control the cellular redox status. Alterations in the ferroptosis-regulating network can contribute to the development of various diseases, including cancer. Evidence suggests that ferroptosis is commonly suppressed in cancer cells, allowing them to survive and progress. However, cancer cells which are resistant to common chemotherapeutic drugs seem to be highly susceptible to ferroptosis inducers, highlighting the great potential of pharmacologic modulation of ferroptosis for cancer treatment. Non-coding RNAs (ncRNAs) are considered master regulators of various cellular processes, particularly in cancer where they have been implicated in all hallmarks of cancer. Recent work also demonstrated their involvement in the molecular control of ferroptosis. Hence, ncRNA-based therapeutics represent an exciting alternative to modulate ferroptosis for cancer therapy. This review summarizes the ncRNAs implicated in the regulation of ferroptosis in cancer and highlights their underlying molecular mechanisms in the light of potential therapeutic applications.