In-vitro rescue and recovery studies of human melanoma (BLM) cell growth, adhesion and migration functions after treatment with progesterone.

Treatment of human melanoma (BLM) cells for 48 hrs with progesterone resulted in a significant inhibition of cell growth. The mechanism of growth inhibition was due to autophagy and this action of progesterone was not mediated through progesterone receptor. As cells were floating during treatment, adhesion assay was performed, which showed complete loss of adhesion. When cells were allowed to recover after treatment by culturing in growth medium without progesterone, there was recovery in cell growth. Preliminary experiments on adhesion and recovery cell growth prompted us to suppress autophagic lysosomal degradation with 3-methyladenine (3-MA), which resulted in partial rescue of cell growth, adhesion and migration functions. The above experimental design gave rise to two experimental groups viz., progesterone treated and 3-MA rescued. Since, recovery studies also showed improvement in cell growth, progesterone treated and 3-MA rescued groups were allowed to recover on their own for first 48 hrs and then a second 48 hrs. Comparison of in-vitro cell growth, adhesion and migration functions of progesterone treated, 3-MA rescued and recovered human melanoma cells revealed that the recovery of 3-MA rescued cells was better than the recovery of progesterone treated cells in terms of cell growth and adhesion functions. These in-vitro experiments not only provided the scientific basis for epidemiological findings that menstruating females were better protected in melanoma, but also showed the potential of progesterone to act as an anti-cancer agent for melanoma treatment.