Humic acid enhances the cytotoxic effects of arsenic trioxide on human cervical cancer cells

Leukemia-associated gene MLAA-34 reduces arsenic trioxide-induced apoptosis in HeLa cells via activation of the Wnt/β-catenin signaling pathway

Our laboratory previously used the SEREX method in U937 cells and identified a novel leukemia-associated gene MLAA-34, a novel splice variant of CAB39L associated with acute monocytic leukemia, that exhibited anti-apoptotic activities in U937 cells. Whether MLAA-34 has an anti-apoptotic role in other tumor cells has not yet been reported. We explored whether MLAA-34 exhibited anti-apoptotic effects in HeLa cervical cancer cells and the possible mechanism of action. We generated a HeLa cell line stably expressing MLAA-34 and found that MLAA-34 overexpression had no effect on the growth, apoptosis and cell cycle of HeLa cells. However, upon treatment with arsenic trioxide (ATO) to induce apoptosis, the cell viability and colony formation ability of ATO-treated MLAA-34 stable HeLa cells were significantly higher than that of ATO-treated controls, and the apoptosis rate and proportion of G2/M cells also decreased. We found that ATO treatment of HeLa cells resulted in significant decreases in the expression of β-catenin mRNA and protein and the downstream target factors c-Myc, cyclin B1, and cyclin D1 in the Wnt signaling pathway. Notably, ATO-treated MLAA-34 stable HeLa cells showed a significant reduction in the ATO-mediated downregulation of these factors. In addition, MLAA-34 overexpression significantly increased the expression of nuclear β-catenin protein in ATO-treated cells compared with HeLa cells treated only with ATO. Thus, here we have found that the Wnt/β-catenin signaling pathway is involved in ATO-induced apoptosis in HeLa cells. MLAA-34 reduces ATO-induced apoptosis and G2/M arrest, and the anti-apoptotic effect may be achieved by activating the Wnt/β-catenin signaling pathway in HeLa cells.

Possible role of nanocarriers in drug delivery against cervical cancer

Introduction: Cervical cancer is the second most common cancer and the largest cancer killer among women in most developing countries including India. Although, various drugs have been developed for cervical cancer, treatment with these drugs often results in a number of undesirable side effects, toxicity and multidrug resistance (MDR). Also, the outcomes for cervical cancer patients remain poor after surgery and chemo radiation. Methods: A literature search (for drugs and delivery systems against cervical cancer) was performed on PubMed and through Google. The present review discuss about various methods including its current conventional treatment with special reference to recent advances in delivery systems encapsulating various anticancer drugs and natural plant products for targeting towards cervical cancer. The role of photothermal therapy, gene therapy and radiation therapy against cervical cancer is also discussed. Results: Systemic/targeted drug delivery systems including liposomes, nanoparticles, hydrogels, dendrimers etc. and localized drug delivery systems like cervical patches, films, rings etc. are safer than the conventional chemotherapy which has further been proved by the several drug delivery systems undergoing clinical trials. Conclusion: Novel approaches for the aggressive treatment of cervical cancer will optimistically result in decreased side effects as well as toxicity, frequency of administration of existing drugs, to overcome MDR and to increase the survival rates.

Environmentally relevant concentration of arsenic trioxide and humic acid promoted tumor progression of human cervical cancer cells: In vivo and in vitro studies

In a previous study, treatment at higher concentrations of arsenic trioxide or co-exposure to arsenic trioxide and humic acid was found to be inhibited cell growth of cervical cancer cells (SiHa cells) by reactive oxygen species generation. However, treatment at lower concentrations slightly increased cell viability. Here, we investigate the enhancement of progression effects of environmentally relevant concentration of humic acid and arsenic trioxide in SiHa cell lines in vitro and in vivo by measuring cell proliferation, migration, invasion, and the carcinogenesis-related protein (MMP-2, MMP-9, and VEGF-A) expressions. SiHa cells treated with low concentrations of humic acid and arsenic trioxide alone or in co-exposure significantly increased reactive oxygen species, glutathione levels, cell proliferation, scratch wound-healing activities, migration abilities, and MMP-2 expression as compared to the untreated control. In vivo the tumor volume of either single drug (humic acid or arsenic trioxide) or combined drug-treated group was significantly larger than that of the control for an additional 45 days after tumor cell injection on the back of NOD/SCID mice. Levels of MMP-2, MMP-9, and VEGF-A, also significantly increased compared to the control. Histopathologic effects of all tumor cells appeared round in cell shape with high mitosis, focal hyperkeratosis and epidermal hyperplasia in the skin, and some tumor growth in the muscle were observed. Our results may indicate that exposure to low concentrations of arsenic trioxide and humic acid is associated with the progression of cervical cancer. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1121-1132, 2016.

Mineral pitch induces apoptosis and inhibits proliferation via modulating reactive oxygen species in hepatic cancer cells

Background

Mineral Pitch (MP) is a dark brown coloured humic matter originating from high altitude rocks. It is an Ayurvedic medicinal food, commonly used by the people of the Himalayan regions of Nepal and India for various body ailments.

Methods

The Huh-7 cells were treated with different concentrations of MP for 24 h, and both apoptosis and proliferation was determined by the TUNEL and MTT assays respectively. The formation of ROS and nitric oxide was analysed by DCFH-DA and Griess reagent respectively. The expression of miRNA-21 and miRNA-22 were checked by the real time PCR. Effect of miRNA-22 on proliferation and c-myc was studied by over-expressing miRNA-22 premiRs in Huh-7 cells.

Results

We found that MP enhanced anti-cancer effects by inducing apoptosis and inhibiting proliferation. MP induced both ROS and NO, upon neutralizing them, there was a partial recovery of apoptosis and proliferation. MP also induced miRNA-22 expression, while miRNA-21 expression was inhibited. Over-expression of miRNA-22 resulted in a significant inhibition of proliferation. miRNA-22 directly targeted c-myc gene, thereby inhibited proliferation. These results clearly show that MP induces its anti-cancer activity by more than one pathway.

Conclusion

The data clearly indicate that MP induced apoptosis via the production of ROS, and inhibited proliferation by inducing miRNA-22 and inhibiting miRNA-21 in Huh-7 cells.

Mechanism of the toxicity induced by natural humic acid on human vascular endothelial cells

Humic acid (HA), a group of high-molecular weight organic compounds characterized by an ability to bind heavy metals, is normally found in natural water. Although the impairment of vascular endothelial cells in the presence of humic substances has been reported to be involved in some diseases, the mechanisms responsible for this involvement remain unclear. In this study, we examined the cytotoxicity of HA obtained from peatland in Central Kalimantan, Indonesia, to human vascular endothelial cells, as well as the mechanisms behind these effects. It was found that 50 mg/L HA showed cytotoxicity, which we considered to be mediated by apoptosis through the mitochondrial pathway because of an increase in the expression of caspases 6 and 9 in response to HA administration. In addition, this cytotoxicity was enhanced when cells in this experimental system were exposed to oxidative stress, while it was decreased by the addition of vitamin C. Thus, we conclude that the apoptosis induced by HA depends upon oxidative stress. Furthermore, an iron chelator, DFO, showed a tendency to decrease HA-induced cytotoxicity, suggesting that iron may potentially mediate HA-induced oxidative stress. In conclusion, long-term consumption of HA-rich water obtained from our study area may cause damage to endothelial cells and subsequent chronic health problems.

Chitosan, the marine functional food, is a potent adsorbent of humic acid

Chitosan is prepared by the deacetylation of chitin, the second-most abundant biopolymer in nature, and has applicability in the removal of dyes, heavy metals and radioactive waste for pollution control. In weight-reduction remedies, chitosan is used to form hydrogels with lipids and to depress the intestinal absorption of lipids. In this study, an experimental method was implemented to simulate the effect of chitosan on the adsorption of humic acid in the gastrointestinal tract. The adsorption capacity of chitosan was measured by its adsorption isotherm and analyzed using the Langmuir equation. The results showed that 3.3 grams of humic acid was absorbed by 1 gram of chitosan. The adsorption capacity of chitosan was much greater than that of chitin, diethylaminoethyl-cellulose or activated charcoal. Cellulose and carboxymethyl-cellulose, a cellulose derivative with a negative charge, could not adsorb humic acid in the gastrointestinal tract. This result suggests that chitosan entraps humic acid because of its positive charge.