한국인 위암세포에 미치는 Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)의 세포사멸 효과 및 분자기전 연구 = Cytotoxic Effects of Tumor Necrosis Factor-related Apoptosis-inducing Ligand (TRAIL) and its Molecular Mechanism in Human Gastric Cancer Cells

다국어 초록 (Multilingual Abstract)

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in some cancer cells such as breast, prostate, lung, and colon cancer cells, but not normal cells. However, because the effects of TRAIL in gastric cancer cells is unclear, we undertook this study to clarify the effects of TRAIL and its mechanism.
To assess the cytotoxicity of TRAIL, two human gastric cancer cell lines, SNU-484 and SNU601, were treated with
TRAIL (0-200 ng/mL) in the presence or absence of cycloheximide (1 μg/mL) for 24 h. Both SNU-484 and SNU-601
were sensitive to TRAIL-induced cell death in a dose-dependent manner. The combination of TRAIL (100 ng/mL) and
cycloheximide (1 μg/mL) for 24 h enhanced cell death and PARP cleavage by promoting activations of caspase-8,
caspase-9, and caspase-3, relative to that of TRAIL alone. We further examined the expressions of death eceptor 4(DR4), death receptor 5 (DR5), and FLICE inhibitory protein (FLIP). Although DR4 and DR5 were expressed in both cell lines, the expression of long form (FLIPL) and short form (FLIPS) of FLIP were detected at the low levels.
Overexpression of FLIPL or FLIPS in both cell lines rendered the cells resistant to TRAIL. Taken together, our results suggest that FLIP promotes human gastric cancer cell survival against TRAIL-induced apoptosis and is important modulator for TRAIL-induced cell death in human gastric cancer cells.

다국어 초록 (Multilingual Abstract)

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)는 유방암, 전립선암, 폐암, 대장암 등 여러 암세포에서 세포사멸을 유발하지만 정상세포에는 영향을 미치지 않는 것으로 알려져 있다. 그러나 TRAIL이 위암세포에 미치는 효과에 대해서는 연구가 미약하다. 따라서 본 연구에서는 한국인 위암세포에서 TRAIL의 세포사멸 효과와 기전을 알아보고자 하였다. 한국인 위암세포주, SNU-484 세포와 SNU-601 세포에 TRAIL (0~200 ng/mL)과 단백 합성 제해제인 cycloheximide (1 μg/mL)를 24시간 동안 단독 또는 병용 투여하여 세포독성을 관찰하였다. SNU-484 세포와 SNU-601 세포는 모두 TRAIL에 대해 용량의존적으로 세포독성을 보였다.
TRAIL과 cycloheximide를 병용투여 하였을 때에는 세포사멸이 TRAIL 단독투여군에 비하여 상승적으로 증가하였다. 또한 TRAIL (100 ng/mL) 투여 후 24시간에 caspase-8, caspase-9과 caspase-3의 활성 및 poly (ADP-ribose) polymerase (PARP)의 절편이 모두 관찰되었으며 이러한 효과는 cycloheximide (1 μg/mL)와 병용하였을 때 더욱 증가하였다. 나아가 TRAIL 수용체들의 발현을 관찰한 결과 TRAIL의 세포사멸 유도 수용체인 death receptor 4(DR4)와 death receptor 5 (DR5)가 SNU-484와 SNU-601 세포 모두에서 발현되었다. 반면 caspase-8의 활성을 저해하는 FLICE-like inhibitory protein (FLIP)의 발현은 SNU-484와 SNU-601 세포에서 모두 낮게 나타났으며 이들 세포에 FLIP 유전자를 과발현시켰을 때에는 TRAIL에 의한 세포사멸 효과가 억제되는 것으로 나타났다. 이러한 결과는 SNU-484와 SNU-601 세포에서 TRAIL이 수용체를 통하여 caspase들을 활성화시킴으로써 세포사멸을 유도하고 FLIP 유전자의 발현이 이러한 세포사멸 효과를 억제하는데 있어서 중요한 역할을 하는 것으로 사료된다.

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