秋山 秀彦

近年,大規模言語モデル(large language models;LLM)が世界的に様々な分野で注目を集めている。LLMとは,非常に巨大なデータセットとディープラーニング技術を用いて構築された言語モデルである。LLMは,人間に近い流暢な会話が可能であら,自然言語を用いたさまざまな処理を高精度で行えることから,世界中で注目を集めている。本研究では,LLMであるOpenAI社が開発したChatGPTの異なる2つのモデル(GPT-3.5,GPT-4)にて,過去3年間の臨床検査技師国家試験におけるChatGPTの正答率について評価を行った。GPT-3.5による正答率の平均は51.4%であった。一方,GPT-4では79.8%の正答率結果が得られた。本結果より,ChatGPTはこの先医療現場における有効なアドバイザーとして進化する可能性をもつことが示唆された。しかし,今回不正解となった20%の中には,患者を診断する際に誤診につながりかねない回答が含まれており,今後のChatGPTの精度向上は必須と考えられる。今回の検証は,LLMにおけるChatGPTの臨床検査領域での多様な応用の進展に寄与すると考えられ,この先の発展に期待したい。(著者抄録)

OBJECTIVES: Agaritine (AGT) is a hydrazine-containing compound derived from the mushroom Agaricus blazei Murill. We previously reported the antitumor effect of AGT on hematological tumor cell lines and suggested that AGT induces apoptosis in U937 cells via caspase activation. However, the antitumor mechanism of AGT has not been fully understood. METHODS: Four hematological tumor cell lines (K562, HL60, THP-1, H929) were used in this study. The cells were incubated in the presence of 50 μM AGT for 24 h and analyzed for cell viability, annexin V positivity, caspase-3/7 activity, mitochondrial membrane depolarization, cell cycle, DNA fragmentation, and the expression of mitochondrial membrane-associated proteins (Bax and cytochrome c). RESULTS: In HL60, K562, and H929 cells, AGT reduced cell viability and increased annexin V- and dead cell-positive rates; however, it did not affect THP-1 cells. In K562 and HL60 cells, caspase-3/7 activity, mitochondrial membrane depolarization, and expression of mitochondrial membrane proteins, Bax and cytochrome c, were all increased by AGT. Cell cycle analysis showed that only K562 exhibited an increase in the proportion of cells in G2/M phase after the addition of AGT. DNA fragmentation was also observed after the addition of AGT. CONCLUSIONS: These results indicate that AGT induces apoptosis in K562 and HL60 cells, like U937 reported previously, but showed no effect on THP-1 cells. It was suggested that AGT-induced apoptosis involves the expression of Bax and cytochrome c via mitochondrial membrane depolarization.

Background: Andrographolide (Andro) is a diterpenoid component of the plant Andrographis paniculata that is known for its anti-tumor activity against a variety of cancer cells.   Methods: We studied the effects of Andro on the viability of the human leukemia monocytic cell line THP-1 and the human multiple myeloma cell line H929. Andro was compared with cytosine arabinoside (Ara-C) and vincristine (VCR), which are well-established therapeutics against hematopoietic tumors. The importance of reactive oxygen species (ROS) production for the toxicity of each agent was investigated by using an inhibitor of ROS production, N-acetyl-L-cysteine (NAC).    Results:  Andro reduced the viability of THP-1 and H929 in a dose-dependent manner. H929 viability was highly susceptible to Andro, although only slightly susceptible to Ara-C. The agents Andro, Ara-C, and VCR each induced apoptosis, as shown by cellular shrinkage, DNA fragmentation, and increases in annexin V-binding, caspase-3/7 activity, ROS production, and mitochondrial membrane depolarization. Whereas Ara-C and VCR increased the percentages of cells in the G0/G1 and G2/M phases, respectively, Andro showed little or no detectable effect on cell cycle progression. The apoptotic activities of Andro were largely suppressed by NAC, an inhibitor of ROS production, whereas NAC hardly affected the apoptotic activities of Ara-C and VCR.  Conclusions: Andro induces ROS-dependent apoptosis in monocytic leukemia THP-1 and multiple myeloma H929 cells, underlining its potential as a therapeutic agent for treating hematopoietic tumors. The high toxicity for (thus forming: The high toxicity for H929 cells, by a mechanism that is different from that of Ara-C and VCR, is encouraging for further studies on the use of Andro against multiple myeloma.) H929 cells, by a mechanism that is different from that of Ara-C and VCR, is encouraging for further studies on the use of Andro against multiple myeloma.