Arginine magic: Arginine kills tumor cells when presented in saline

There has been no anti‐cancer formulation so far, which is sufficiently effective for the treatment of cancer using an endogenous molecule. Various scientists have attempted to describe the complex role of arginine in cancer biology and treatment. Nobody has yet looked at the non‐substrate actions of arginine, to act as a Biological Response Modifier through its chemical structure. Arginine containing peptides have been used as delivery vectors to carry payloads of drugs. The results indicate that guanidinium group is critical for the translocation process. Based on the above, we hypothesized that pharmacological doses of L‐arginine (LA) when delivered in saline could interact with tumour cells more efficiently. Various tumor cell lines derived from mouse and human when incubated with LA, D‐arginine (DA) in pharmacological doses in PBS, caused the death of tumor cells, as assessed by the membrane integrity test, trypan dye exclusion test and MTT assay. There was complete destruction of cell structure (Fig.1). DA had better anticancer ability as it could inhibit the tumor growth at lower concentration. The anticancer property of LA is not accompanied by any toxicity to the red blood cells or NIH 3T3 cells. L‐lysine and agmatine did not offer any antitumor activity. Arginine administered in PBS could also cure the mice of the tumor transplanted into the peritoneum (Fig. 2). These findings provide a previously unrecognized beneficial effect of guanidinium group containing compounds in killing the tumor cells and thus provide new potential approaches for therapeutic development of arginine in tumor therapy.