β-carotene is present in carrots, pumpkins, and sweet potatoes. It suppresses many types of cancers by regulating cellular proliferation and apoptosis through a variety of mechanisms. However, the effects of β -carotene on oral cancer cells have not been clearly established. The main goal of this study was to investigate the effects of β-carotene on cell growth and apoptosis in oral cancer cells. Our results demonstrate that treatment with β-carotene induced inhibition of cell growth, and that the effect was dependent on β-carotene treatment time and concentration in KB cells. Furthermore, treatment with β-carotene induced nuclear condensation and fragmentation in KB cells. β-carotene promoted proteolytic cleavage of procaspase-3, -7, -8 and –9 with associated increases in the concentration of cleaved caspase-3, -7, -8 and –9. In addition, the level of cleaved PARP was increased by β-carotene treatment in KB cells. These results suggest that β-carotene can suppress cell growth and induce apoptosis in KB human oral cancer cells, and that it may have potential usefulness in anti-cancer drug discovery efforts.

Introduction
 Materials and Methods
  Materials
  Cell line and cell cultures
  Cell proliferation assay
  Nuclear staining with DAPI
  DNA fragmentation analysis
  Immunoblotting
  Data analysis
 Results
  Cytotoxic effect of β-carotene in KB cells
  Changes in the nuclear morphology by β-carotene
  DNA fragmentation
  Activation of caspases by β-carotene
 Discussion
 References

• Sung-Su Yang(Oral Biology Research Institute, School of Dentistry, Chosun University, Gwangju 61452, Republic of Korea)
• Su-Gwan Kim(Oral Biology Research Institute, School of Dentistry, Chosun University, Gwangju 61452, Republic of Korea)
• Byung-Sun Park(Oral Biology Research Institute, School of Dentistry, Chosun University, Gwangju 61452, Republic of Korea)
• Dae-San Go(Oral Biology Research Institute, School of Dentistry, Chosun University, Gwangju 61452, Republic of Korea)
• Sun-Kyoung Yu(Oral Biology Research Institute, School of Dentistry, Chosun University, Gwangju 61452, Republic of Korea)
• Chun Sung Kim(Oral Biology Research Institute, School of Dentistry, Chosun University, Gwangju 61452, Republic of Korea)
• Jeongsun Kim(Department of Dental Hygiene, Gwangju Health University, Gwangju 62287, Republic of Korea)
• Do Kyung Kim(Oral Biology Research Institute, School of Dentistry, Chosun University, Gwangju 61452, Republic of Korea) Corresponding Author