Human Recombinant Arginase I [HuArgI(Co)-PEG5000]-Induced Arginine Depletion Inhibits Pancreatic Cancer Cell Migration and Invasion Through Autophagy.

OBJECTIVES: Pancreatic cancer is one of the most aggressive solid cancers and the fourth leading cause of cancer death in men and women. We previously showed that arginine depletion, using arginase I [HuArgI(Co)-PEG5000], selectively triggers cell death by autophagy in PANC-1 pancreatic cancer cells. The mechanism of action of [HuArgI(Co)-PEG5000], however, has remained poorly understood. In this study, we investigated the effects of arginine depletion on PANC-1 cell migration, adhesion, and invasion and determined the main molecular targets, which mediate PANC-1 cell response to treatment with HuArgI(Co)-PEG5000. METHODS: This was done through examining 2-dimensional (2D) cell motility assays (wound healing and time lapse), cell adhesion, and cell invasion assays, as well as immunostaining for focal adhesions and invadopodia in cells without or with the treatment with arginase. RESULTS: We demonstrate that arginine depletion decreases PANC-1 2D cell migration, adhesion, and 3D invasion. Moreover, our data suggest that these effects are mediated by autophagy and subsequent decrease in the activation of members of Ras homolog gene family (Rho) GTPase family. CONCLUSIONS: Altogether, these findings uncover the mechanism of action of [HuArgI(Co)-PEG5000] and highlight the promising and selective anticancer potential for arginine depletion in the treatment of pancreatic cancer cells.

Human recombinant arginase I [HuArgI (Co)-PEG5000]-induced arginine depletion inhibits ovarian cancer cell adhesion and migration through autophagy-mediated inhibition of RhoA.

Ovarian carcinoma is the second most common malignancy of the female reproductive system and the leading cause of death from female reproductive system malignancies. Cancer cells have increased proliferation rate and thus require high amounts of amino acids, including arginine. L-arginine is a non-essential amino acid synthesized from L-citrulline by the Arginosuccinate synthetase (ASS1) enzyme. We have previously shown that the ovarian cancer cells, SKOV3, are auxotrophic to arginine, and that arginine deprivation by treatment with the genetically engineered human arginase I (HuArgI (Co)-PEG5000) triggers the death of SKOV3 cells by autophagy. In this study we examine the effect of HuArgI (Co)-PEG5000 on ovarian cancer cell migration and we dissect the mechanism involved. Wound healing assays, 2D random cell migration assays and cell adhesion analysis indicate that arginine deprivation decreases SKOV3 cell migration and adhesion. This effect was mimicked when autophagy was induced through rapamycin and reversed with the autophagy inhibitor chloroquine when autophagy was inhibited. This proved that arginine deprivation leads to the inhibition of cancer cell migration through autophagy, in addition to cell death. In addition, we were able to establish through pull-down assays and reversal experiments, that arginine deprivation-mediated autophagy inhibits cell migration through a direct inhibition of RhoA, member of the Rho family of GTPases. In conclusion, here we identify, for the first time, an autophagy-mediated inhibition of RhoA that plays an important role in regulating ovarian cancer cells motility and adhesion in response to arginine depletion.

Arginine deprivation: a potential therapeutic for cancer cell metastasis? A review.

Arginine is a semi essential amino acid that is used in protein biosynthesis. It can be obtained from daily food intake or synthesized in the body through the urea cycle using l-citrulline as a substrate. Arginine has a versatile role in the body because it helps in cell division, wound healing, ammonia disposal, immune system, and hormone biosynthesis. It is noteworthy that l-arginine is the precursor for the biosynthesis of nitric oxide (NO) and polyamines. In the case of cancer cells, arginine de novo synthesis is not enough to compensate for their high nutritional needs, forcing them to rely on extracellular supply of arginine. In this review, we will go through the importance of arginine deprivation as a novel targeting therapy by discussing the different arginine deprivation agents and their mechanism of action. We will also focus on the factors that affect cell migration and on the influence of arginine on metastases through polyamine and NO.