Fas death pathway in sarcomas correlates with epidermal growth factor transcription

Hepatocyte apoptosis is triggered by hepatic inflammation in common carp acutely exposed to microcystin-LR or chronically exposed to Microcystis

Cyanobacterial blooms pose a serious threat to the survival of fish because of the hepatotoxicity of microcystins produced by toxic cyanobacteria such as Microcystis. Many studies have investigated the hepatotoxicity of microcystins in common carp, a freshwater fish distributed worldwide, but the hepatotoxicity mechanism has not been fully clarified. The present study aimed to investigate the mechanism underlying the hepatic inflammatory response and hepatocyte apoptosis induced by acute microcystin-LR exposure via intraperitoneal injection (71 μg/kg and 119 μg/kg) or gavage (357.08 μg/kg) and chronic exposure to toxic Microcystis blooms. The results of acute exposure revealed that microcystin-LR caused an increase in serum transaminase activity and increased the levels of inflammatory factors and inflammatory mediators, inducing a significant inflammatory response in the liver of common carp. Moreover, biochemical detection revealed that hepatocyte apoptosis occurred in the fish. Moreover, chronic toxic Microcystis exposure also caused hepatic inflammation and subsequent apoptosis mediated by the tumour necrosis factor-α (TNF-α) pathway and the mitochondrial pathway similar to acute exposure. Therefore, our study suggests that the inflammatory response induced by microcystin-LR exacerbates apoptosis, likely mediated by TNF-α. In summary, both acute microcystin-LR exposure and chronic toxic Microcystis exposure can cause inflammation in the liver of common carp, which subsequently triggers hepatocyte apoptosis mediated by the TNF-α pathway and the mitochondrial pathway. This study helps elucidate the mechanism of liver damage induced by cyanobacterial blooms in natural water.

Obesity Does Not Exacerbate the Protumorigenic Systemic Environment in Sarcoma Subjects

Sarcomas are a rare but fatal tumor type that accounts for <1% of adult solid malignancies and ~15% of childhood malignancies. Although the use of immunotherapy is being actively investigated for other solid tumors, advances in immunotherapy for sarcoma patients are lacking. To better understand the systemic immune environment in sarcoma patients, we performed a detailed multiplex analysis of serum cytokines, chemokines, and protumorigenic factors from treatment-naive subjects with localized, high-grade sarcoma. Because obesity is a major healthcare issue in the United States, we additionally examined the effects of obesity on serum protein profiles in our sarcoma subject cohort. We found that the systemic host environment is profoundly altered to favor tumor progression, with epidermal growth factor, angiopoietin-2, vascular endothelial growth factor A, IL-6, IL-8, and MIP-1β all increased relative to tumor-free controls (all p < 0.05). Surprisingly, we found that obesity did not exacerbate this protumorigenic profile, as epidermal growth factor and IL-8 decreased with increasing subject body mass index (both p < 0.05 versus normal or overweight subjects). The Th2-related cytokines IL-4, IL-5, and IL-13 were also decreased in the presence of obesity. Thus, although the systemic environment in sarcoma subjects favors tumor progression, obesity does not further aggravate the production of protumorigenic factors.

Potential for modulation of the fas apoptotic pathway by epidermal growth factor in sarcomas

One important mechanism by which cancer cells parasitize their host is by escaping apoptosis. Thus, selectively facilitating apoptosis is a therapeutic mechanism by which oncotherapy may prove highly advantageous. One major apoptotic pathway is mediated by Fas ligand (FasL). The death-inducing signaling Ccmplex (DISC) and subsequent death-domain aggregations are created when FasL is bound by its receptor thereby enabling programmed cell death. Conceptually, if a better understanding of the Fas pathway can be garnered, an oncoselective prodeath therapeutic approach can be tailored. Herein, we propose that EGF and CTGF play essential roles in the regulation of the Fas apoptotic pathway in sarcomas. Tumor and in vitro data suggest viable cells counter the prodeath signal induced by FasL by activating EGF, which in turn induces prosurvival CTGF. The prosurvival attributes of CTGF ultimately predominate over the death-inducing FasL. Cells destined for elimination inhibit this prosurvival response via a presently undefined pathway. This scenario represents a novel role for EGF and CTGF as regulators of the Fas pathway in sarcomas.

Desmoid cell motility is induced in vitro by rhEGF

Desmoid tumors are benign but locally invasive myofibroblastic lesions that arise predominantly in the abdominal wall or shoulder and are prone to aggressive local recurrences. A perceived association between desmoid activity and the expression of growth factors during pregnancy or following trauma suggests a cause-and-effect relationship between growth factor stimulation and desmoid invasiveness. We used Boyden Chambers to quantify cell motility in order to determine the effect of growth factor stimulation on desmoid cell migration. Desmoid cell cultures were treated under serum-free conditions with epidermal growth factor (rhEGF) or transforming growth factor alpha (rhTGFalpha). Additional cell cultures were pretreated under serum-free conditions with the EGF receptor (EGFR) inhibitor AG1478, alone or in combination with the TGFbeta1 receptor inhibitor SB431542, and then stimulated with growth factor prior to being assayed for cell motility. The experiments demonstrated a direct dose-dependent relationship between rhEGF stimulation and desmoid motility. In contrast, rhTGFalpha was less effective at inducing cell migration. rhEGF-induced cell migration could be diminished, but not reduced to control levels, by inhibiting EGFR. When EGF and TGFbeta1 receptors were inhibited simultaneously, the level of rhEGF-induced cell migration was reduced significantly beyond the level of cell migration generated by inhibition of EGFR alone.