Inositol Hexaphosphate and Paclitaxel: Symbiotic Treatment of Oral Cavity Squamous Cell Carcinoma

New options of cancer treatment employing InsP6

Many mechanistic studies have been performed to analyze the cellular functions of the highly phosphorylated molecule inositol hexakisphosphate (InsP₆) in health and disease. While the physiological intracellular functions are well described, the mechanism of potential pharmacological effects on cancer cell proliferation is still controversial. There are numerous studies demonstrating that a high InsP₆ concentration (≥75 µM) inhibits growth of cancer cells in vitro and in vivo. Thus, there is no doubt that InsP₆ exhibits anticancer activity but the mechanism underlying the cellular effects of extracellular InsP₆ on cancer cells is far from being understood. In addition, studies on the inhibitory effect of InsP₆ on cancer progression in animal models ignore aspects of its bioavailability. Here, we review and critically discuss the uptake mechanism and the intracellular involvement in signaling pathways of InsP₆ in cancer cells. We take into account the controversial findings on InsP₆ plasma concentration, which is a critical aspect of pharmacological accessibility of InsP₆ for cancer treatment. Further, we discuss novel findings with respect to the effect of InsP₆ on normal and immune cells as well as on platelet aggregate size. Our goal is to stimulate further mechanistic studies into novel directions considering previously disregarded aspects of InsP₆. Only when we fully understand the mechanism underlying the anticancer activity of InsP₆ novel and more efficient treatment options can be developed.

Apoptotic effect of cisplatin and cordycepin on OC3 human oral cancer cells

OBJECTIVE

To evaluate apoptotic effects of cisplatin and cordycepin as single agent or in combination with cytotoxicity in oral cancer cells.

METHODS

The influences of cisplatin (2.5 μg/mL) and/or cordycepin treatment (10 or 100 μmol/L) to human OC3 oral cancer cell line were investigated by morphological observation for cell death appearance, methylthiazoletetrazolium (MTT) assay for cell viability, flow cytometry assay for cell apoptosis, and Western blotting for apoptotic protein expressions.

RESULTS

Data demonstrated that co-administration of cisplatin (2.5 μg/mL) and cordycepin (10 or 100 μmol/L) resulted in the enhancement of OC3 cell apoptosis compared to cisplatin or cordycepin alone treatment (24 h), respectively (P <0.05). In flow cytometry assay, percentage of cells arrested at subG1 phase with co-treatment of cordycepin and cisplatin (30%) was significantly higher than cisplatin (5%) or cordycepin (12%) alone group (P <0.05), confirming a synergistically apoptotic effect of cordycepin and cisplatin. In cellular mechanism study, co-treatment of cordycepin and cisplatin induced more stress-activated protein kinase/Jun terminal kinase (JNK), the expressions of caspase-7, and the cleavage of poly ADP-ribose polymerase (PARP) as compared to cisplatin or cordycepin alone treatment (P <0.05).

CONCLUSION

Cisplatin and cordycepin possess synergistically apoptotic effect through the activation of JNK/caspase-7/PARP pathway in human OC3 oral cancer cell line.

Effect of phytic acid on suicidal erythrocyte death

Phytic acid, an anticarcinogenic food component, stimulates apoptosis of tumor cells. Similar to apoptosis, human erythrocytes may undergo suicidal death or eryptosis, characterized by cell membrane scrambling and cell shrinkage. Triggers of eryptosis include energy depletion. Phytate intake could cause anemia, an effect attributed to iron complexation. The present experiments explored whether phytic acid influences eryptosis. Supernatant hemoglobin concentration was determined to reveal hemolysis, annexin V-binding in FACS analysis was utilized to identify erythrocytes with scrambled cell membrane, forward scatter in FACS analysis was taken as a measure of cell volume, and a luciferin-luciferase assay was employed to determine erythrocyte ATP content. As a result, phytic acid (>or=1 mM) did not lead to significant hemolysis, but significantly increased the percentage of annexin V-binding erythrocytes, significantly decreased forward scatter, and significantly decreased cellular ATP content. In conclusion, phytic acid stimulates suicidal human erythrocyte death, an effect paralleling its proapoptotic effect on nucleated cells.