Kumquat essential oil decreases proliferation and activates JNK signaling and apoptosis in HT-1080 fibrosarcoma cells.

Kumquats are small citrus fruits produced by the Fortunella japonica tree. In addition to its aroma, kumquat essential oil may have antiproliferative effects; however, research on the effects of kumquat essential oil on human cell lines is limited. This study investigated the effects of kumquat essential oil on the proliferation of three human cell lines (HT-1080 fibrosarcoma cells, HeLa cervical adenocarcinoma cells, and CUA-4 normal human fibroblasts). As the concentration of kumquat essential oil increased, cell proliferation and viability, as measured by MTT activity assays, decreased in all three cell lines. Compared to untreated cells, HT-1080 fibrosarcoma cells exposed to kumquat essential oil exhibited an increased presence of phosphorylated JNK. Apoptosis was also stimulated, as PARP cleavage of treated HT-1080 fibrosarcoma cells was detected. Use of a JNK inhibitor resulted in decreased PARP cleavage in HT-1080 cells following treatment with kumquat EO, suggesting that activity of JNK is implicated in the stress response. The kumquat essential oil constituents limonene and myrcene both independently led to decreased proliferation and apoptosis.