THE REGULATION OF ROTAVIRUS–INFECTED HT29.F8 AND MA104 CELLS TREATED WITH ARACHIDIN 1 OR ARACHIDIN 3

Rotavirus (RV) infections cause severe life threatening diarrhea in young children and immunocompromised individuals. Several effective vaccines have been developed for young children but are not protective against all strains of RV, and there are no anti-RV therapeutics. Our laboratory has discovered a decrease in the number of infectious simian RV particles (SA114f) in human intestinal cell line, HT29.f8 cells with the addition of either of two stilbenoids, arachidin-1 (A1) or arachidin-3 (A3). This suggests effects on the host cell and RV replication. We examined the cellular effects of human RV strain (Wa) on a human intestinal cell line (HT29.f8) and an African green monkey kidney cell line (MA104) treated with/without either arachidin. Both cell lines demonstrated apoptotic characteristics that were modulated with the addition of either A1 or A3, and the size and population of the released virus particles were significantly altered. Likewise, the number of infectious virus particles released from the arachidin treated cells were significantly reduced. This data supports the RV therapeutic potential of A1 and A3

The Addition of Arachidin 1 or Arachidin 3 to Human Rotavirus-infected Cells Inhibits Viral Replication and Alters the Apoptotic Cell Death Pathway

Rotavirus (RV) infections are a leading cause of severe gastroenteritis in infants and children under the age of five. There are two vaccines available in the United States and one in India that can be administered early in childhood, however they only protect against specific strains1. From our previous work, both arachidin-1 (A1) and arachidin-3 (A3) from peanut (Arachis hypogaea) hairy root cultures significantly inhibit simian RV replication2,3,4. The purpose of this study was to determine if a human intestinal cell line, HT29.f8, infected with a human RV, Wa, was affected by A1 and A3. Cell viability assays were utilized to determine if A1 and A3 affect the HT29.f8 cells with/without RV infections. At eighteen hours post infection (hpi), supernatants from the RV-infected HT29.f8 cells with/without the arachidins were used in plaque forming assays to quantify and compare the amount of infectious RV particles that are produced during an infection. Transmission electron microscopy (TEM) was used to visualize cell ultrastructure and individual RV particles. Additionally, tunable resistive pulse sensing technology (TRPS) using the qNano system by IZON was employed to quantify and measure virus particle sizes, and display the size distribution of RV particles. Likewise, quantitative real time polymerase chain reactions (qRT-PCR) were performed to determine if A1 and A3 regulated cell death pathways in the HT29.f8 cell line. This data will guide our future studies to determine the antiviral mechanism(s) of action of A1 and A3

Propranolol Sensitizes Vascular Sarcoma Cells to Doxorubicin by Altering Lysosomal Drug Sequestration and Drug Efflux

Angiosarcoma is a rare cancer of blood vessel–forming cells with a high patient mortality and few treatment options. Although chemotherapy often produces initial clinical responses, outcomes remain poor, largely due to the development of drug resistance. We previously identified a subset of doxorubicin-resistant cells in human angiosarcoma and canine hemangiosarcoma cell lines that exhibit high lysosomal accumulation of doxorubicin. Hydrophobic, weak base chemotherapeutics, like doxorubicin, are known to sequester within lysosomes, promoting resistance by limiting drug accessibility to cellular targets. Drug synergy between the beta adrenergic receptor (β-AR) antagonist, propranolol, and multiple chemotherapeutics has been documented in vitro, and clinical data have corroborated the increased therapeutic potential of propranolol with chemotherapy in angiosarcoma patients. Because propranolol is also a weak base and accumulates in lysosomes, we sought to determine whether propranolol enhanced doxorubicin cytotoxicity via antagonism of β-ARs or by preventing the lysosomal accumulation of doxorubicin. β-AR-like immunoreactivities were confirmed in primary tumor tissues and cell lines; receptor function was verified by monitoring downstream signaling pathways of β-ARs in response to receptor agonists and antagonists. Mechanistically, propranolol increased cytoplasmic doxorubicin concentrations in sarcoma cells by decreasing the lysosomal accumulation and cellular efflux of this chemotherapeutic agent. Equivalent concentrations of the receptor-active S-(−) and -inactive R-(+) enantiomers of propranolol produced similar effects, supporting a β-AR-independent mechanism. Long-term exposure of hemangiosarcoma cells to propranolol expanded both lysosomal size and number, yet cells remained sensitive to doxorubicin in the presence of propranolol. In contrast, removal of propranolol increased cellular resistance to doxorubicin, underscoring lysosomal doxorubicin sequestration as a key mechanism of resistance. Our results support the repurposing of the R-(+) enantiomer of propranolol with weak base chemotherapeutics to increase cytotoxicity and reduce the development of drug-resistant cell populations without the cardiovascular and other side effects associated with antagonism of β-ARs

Arachidin-1 and Arachidin-3 Modulation of Rotavirus-infected MA104 Cells

Rotavirus (RV) causes severe life-threatening diarrhea in young children and immunocompromised individuals. There are several licensed attenuated vaccines for young children, but there are no vaccines or antiviral therapeutics for immunocompromised patients of any age. Previously, our laboratory demonstrated that arachidin 1 (A1) and arachidin 3 (A3) decreases the number of infectious simian RV particles and RV non-structural protein 4 (NSP4) in a human intestinal cell line which suggests effects on RV replication. This study examined the effects of the arachidins on the human RV (Wa)-infected African green monkey kidney cell line, MA104. The addition of either A1 or A3 did not decrease the viability of MA104 cells, however plaque forming assays measured significant decreases in the number of infectious RV particles with the addition of the arachidins. Correspondingly, western blot analyses revealed a change in the presence of VP6 and NSP4 (structural and nonstructural RV proteins, respectively). This implies that like the simian RV, Wa replication is also affected by both A1 and A3. Additionally, tunable resistive pulse sensing technology (TRPS) measured changes in the population distribution of released nanoparticles between 60-140 nanometers. Additionally, TEM morphometric analyses showed ultrastructural changed in RV-infected cells treated with A1 or A3. This included nucleus to cytoplasm ratios that were determined by TEM and whole cell fluorescent assays that disclosed significant nuclear size alterations with the addition of RV which implied modifications of the apoptosis and autophagy pathways. Moreover, the increased presence of autophagic vesicles seen with RV+A1 reinforced the model of a switch from the apoptosis to the autophagy pathway. In addition, immunoblot assays reveal the presence of cannabinoid 1 and 2 receptors on MA104 cells. These receptors bind A1 and A3 and are important in signaling in the endocannabinoid system. This implies a role for Witcher et al.: Arachidin-1 and Arachidin-3 Modulation of Rotavirus-infected MA10 2 A1 and A3 in modulating cannabinoid receptor cell signaling in RV-infected cells which indicates a mechanism of action of A1 and A3 with potential RV therapeutic activity

A Time Course Study of Rotavirus-Infected Intestinal Cells Treated with Stilbenoids and the Regulation of Apoptosis

This is a time course study of virus –host interactions that are modified with the addition of two small natural products. They appear to effect virus replication and the host response to the infection