L-Ascorbic Acid Enhances Apoptosis in Human Gastric Carcinoma Cell Line AZ-521 Cells Infected with Mycoplasma hyorhinis

Abstract

ABSTRACT. Mycoplasma hyorhinis (M. hyorhinis) exerts multiple effects on cell metabolisms including apoptosis mediated by their endonucleases and nitric oxide production in vitro. Although AsA is preferable to health in general because of its reactive oxygen species scavenging activity, we found that in a human carcinoma cell line AZ-521 infected with M. hyorhinis, apoptosis was enhanced by addition of L-ascorbic acid (AsA) to the cell cultures. No significant differences were evident between the AZ-521 cells with and without AsA (AsA-) after 24 hr of incubation in the mitochondrial fluorescence. M. hyorhinis-infected AZ-521 cells treated with AsA (AsA +) have developed distinct DNA ladders as compared to the control cells AsA-after 24 hr of incubation. Marked cytopathic effects were rather apparent in AsA-treated cells than in control cells AsA-after 24 hr. Our data demonstrate that AsA addition to cell cultures enhances apoptosis induced by M. hyorhinis infection. We suggest that the presence of another external apoptotic pathway by M. hyorhinis infection. While most mycoplasmas are not primarily pathogenic to humans and animals, a few specific maycoplasma species are responsible for chronic and degenerative diseases [26]. Mycoplasma hyorhinis (M. hyorhinis) is causative of polyserositis [3], otitis media [16], arthritis [6], and mycoplasmal pneumonia [11] in piglets, and may lead the swine production to serious situation [30].M. hyorhinis is also a common contaminant in cell cultures [1]. Infection with M. hyorhinis leads the culture cells to apoptosis, which is mediated by their endonucleases [20,21]. We examined the effect of L-ascorbic acid (AsA) to the apoptosis in cultured cells infected by M. hyorhinis, since it has been known that AsA has reactive oxygen species (ROS) scavenging activity by protecting the membrane phospholipids against the peroxidative damage by ROS, and by suppressing ROS production [2,8]. However, dietary taken AsA exhibits a pro-oxidant, which attributes to DNA damage, in healthy humans so it is possible that AsA may play a role in diseases such as cancer, rheumatoid arthritis and atherosclerosis [24].In contrast to our initial assumption that AsA may prevent apoptosis of the cells infected with M. hyorhinis, in the process of the experiments, we found excess AsA addition enhanced apoptosis of the cells infected with M. hyorhinis rather than preventative.In the present study, we demonstrated that a human carcinoma cell line AZ-521 cells infected with M. hyorhinis lead to apoptosis enhanced by addition of AsA, revealed by fluorescence DNA staining and DNA ladder formation, but no significant differences in the mitochondrial fluorescence as compared to the controls. These suggest the presence of another external apoptotic pathway by M. hyorhinis infection. MATERIALS AND METHODS Cell cultures:Human gastric cancer cell line AZ-521 was obtained from the Health Science Research Resources Bank (Osaka). The cell culture was maintained as previously described [31]. To minimize the pH decreas...

Nitric Oxide Causes Anoikis through Attenuation of E-Cadherin and Activation of Caspase-3 in Human Gastric Carcinoma AZ-521 Cells Infected with Mycoplasma hyorhinis

“…Our preliminary examination suggested marked down-regulation of E-cadherin expression in AZ521 cells infected with M. hyorhinis based on a microarray analysis (unpublished data). Therefore, we hypothesized that excessive NO produced by M. hyorhinis infection leads to anoikis in AZ-521 cells.We previously reported that apoptosis in human carcinoma cell line AZ-521 infected with M. hyorhinis was enhanced by addition of L-ascorbic acid (AsA) to the cell cultures [21]. Since M. hyorhinis infection and/or AsA addition enhance iNOS activity [20], we proposed a hypothesis that M. hyorhinis infection results in the presence of another external apoptotic pathway including the NO pathway.…”

“…We previously reported that apoptosis in human carcinoma cell line AZ-521 infected with M. hyorhinis was enhanced by addition of L-ascorbic acid (AsA) to the cell cultures [21]. Since M. hyorhinis infection and/or AsA addition enhance iNOS activity [20], we proposed a hypothesis that M. hyorhinis infection results in the presence of another external apoptotic pathway including the NO pathway.…”

Clinical efficacy and safety of oral and intravenous vitamin C use in patients with malignant diseases

“…With regard to the effects of vitamin C in cancer cells, it is known that it acts as an antioxidant at physiological levels and it could be linked to pro-oxidant effects at pharmacological doses which promote the death of cancer cells (Chen et al 2005 , 2007 ). Various in vitro studies have already shown that high concentrations of vitamin C led to apoptosis of cancer cells (Chen et al 2005 ; Ha et al 2009 ; Harakeh et al 2007 ; Hong et al 2007 ; Kim et al 2012 ; Obara and Harasawa 2008 ). So far, several mechanisms have been described in vitro which give a more detailed insight into the molecular pathways which contribute to the induction of apoptosis (Irimie et al 2019 ).…”

Protective effect of vitamin C on biochemical alterations induced by subchronic co-administration of chlorpyrifos and lead in Wistar rats

“…CPF and lead have been shown to increase the production of free radical and decrease the availability of antioxidant molecules that mitigate the resultant damage. Vitamin C is a low-molecular weight antioxidant molecule that protects the cellular compartment from hydrophilic oxygen-nitrogen radicals; a property that makes it an efficacious antioxidant of the hydrophilic phase [23,24]. Earlier studies have shown the ability of vitamin C to mitigate toxicity induced by CPF [1,14,16,19,25] and lead [26][27][28][29].…”