Acute myeloid leukemia (AML) is characterized by the accumulation of immature myeloid cells and a differentiation block, highlighting the urgent need for novel differentiation-inducing therapies. This study evaluated Adina rubella Hance (ARH) stem as a potent differentiation inducer by systematically screening 200 plant extracts. ARH stem promoted phenotypic differentiation in AML cells. In addition to its differentiation-inducing effects, ARH stem exhibited strong antileukemic activities, such as inhibiting cell proliferation, inducing cell death, and enhancing mitochondrial reactive oxygen species (mtROS) levels, the latter of which is critical for its differentiation-promoting activity. Comparative analysis with the extracts from other parts of the plant confirmed the superior efficacy of the stem extract because of its unique chemical composition. Ultra-high-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry analysis identified Picroside III as a major active compound within the stem extract, capable of recapitulating ARH stem-induced differentiation and demonstrating significant antileukemic properties. These findings underscore the therapeutic potential of ARH stem and its active component, Picroside III, as promising agents for differentiation-based treatment strategies in AML.

Overexpression of cancer upregulated gene (CUG) 2 induces cancer stem cell-like phenotypes, such as enhanced epithelial-mesenchymal transition, sphere formation, and doxorubicin resistance. However, the precise mechanism of CUG2-induced oncogenesis remains unknown. We evaluated the effects of overexpression of CUG2 on microRNA levels using a microRNA microarray. Levels of miR-3656 were decreased when CUG2 was overexpressed; on the basis of this result, we further examined the target proteins of this microRNA. We focused on Jumonji C domain-containing protein 5 (JMJD5), as it has not been previously reported to be targeted by miR-3656. When CUG2 was overexpressed, JMJD5 expression was upregulated compared to that in control cells. A 3′ untranslated region (UTR) assay revealed that an miR-3656 mimic targeted the JMJD5 3′UTR, but the miR-3656 mimic failed to target a mutant JMJD5 3′UTR, indicating that miR-3656 targets the JMJD5 transcript. Administration of the miR-3656 mimic decreased the protein levels of JMD5 according to Western blotting. Additionally, the miR-3656 mimic decreased CUG2-induced cell migration, evasion, and sphere formation and sensitized the cells to doxorubicin. Suppression of JMJD5, with its small interfering RNA, impeded CUG2-induced cancer stem cell-like phenotypes. Thus, overexpression of CUG2 decreases miR-3656 levels, leading to upregulation of JMJD5, eventually contributing to cancer stem cell-like phenotypes.

Aralia continentalis has been used in Korea as a folk remedy for arthralgia, rheumatism, and inflammation. However, its anti-lymphoma effect remains uncharacterized. Here, we demonstrate that A. continentalis extract and its three diterpenes efficiently kill B-lymphoma cells. Our in vitro and in vivo results suggest that the cytotoxic activities of continentalic acid, a major diterpene from A. continentalis extract, are specific towards cancer cells while leaving normal murine cells and tissues unharmed. Mechanistically, continentalic acid represses the expression of pro-survival Bcl-2 family members, such as Mcl-1 and Bcl-xL. It dissociates the mitochondrial membrane potential, leading to the stimulation of effector caspase 3/7 activities and, ultimately, cell death. Intriguingly, this agent therapeutically synergizes with roflumilast, a pan-PDE4 inhibitor that has been successfully repurposed for the treatment of aggressive B-cell malignancies in recent clinical tests. Our findings unveiled that A. continentalis extract and three of the plant’s diterpenes exhibit anti-cancer activities. We also demonstrate the synergistic inhibitory effect of continentalic acid on the survival of B-lymphoma cells when combined with roflumilast. Taken in conjunction, continentalic acid may hold significant potential for the treatment of B-cell lymphoma.

The proto-oncogene MYC is frequently dysregulated in patients with diffuse large B-cell lymphoma (DLBCL) and plays a critical role in disease progression. To improve the clinical outcomes of patients with DLBCL, the development of strategies to target MYC is crucial. The use of medicinal plants for developing anticancer drugs has garnered considerable attention owing to their diverse mechanisms of action. In this study, 100 plant extracts of flora from the Republic of Korea were screened to search for novel agents with anti-DLBCL effects. Among them, Ajania pacifica (Nakai) K. Bremer and Humphries extract (APKH) efficiently suppressed the survival of DLBCL cells, while showing minimal toxicity toward normal murine bone marrow cells. APKH suppressed the expression of anti-apoptotic BCL2 family members, causing an imbalance between the pro-apoptotic and anti-apoptotic BCL2 members. This disrupted mitochondrial membrane potential, cytochrome c release, and pro-caspase-3 activation and eventually led to DLBCL cell death. Importantly, MYC expression was markedly downregulated by APKH and ectopic expression of MYC in DLBCL cells abolished the pro-apoptotic effects of APKH. These results demonstrate that APKH exerts anti-DLBCL effects by inhibiting MYC expression. Moreover, when combined with doxorubicin, an essential component of the CHOP regimen (cyclophosphamide, doxorubicin, vincristine, and prednisone), APKH synergistically enhanced the therapeutic effect of doxorubicin. This indicates that APKH may overcome drug resistance, which is common in patients with refractory/relapsed DLBCL. To identify compounds with anti-DLBCL activities in APKH, the chemical profile analysis of APKH was performed using UPLC-QTOF/MS^e analysis and assessed for its anticancer activity. Based on the UPLC-QTOF/MS^e chemical profiling, it is conceivable that APKH may serve as a novel agent targeting MYC and sensitizing drug-resistant DLBCL cells to CHOP chemotherapy. Further studies to elucidate how the compounds in APKH exert tumor-suppressive role in DLBCL are warranted.

Acute myeloid leukemia (AML) is a type of hematological malignancy with a poor prognosis caused by diverse genetic mutations. One effective treatment approach is to induce the differentiation of AML cells, which may help curb their unrestrained proliferation. In search of novel differentiation-inducing drug candidates, a phenotypic screen of a chemical library was performed, and Azvudine, a new anti-HIV agent approved by the China FDA in 2021, was identified as the most effective agent. Azvudine efficiently drove differentiation in multiple human AML cell lines, which was strongly associated with G2/M cell cycle arrest and apoptosis in vitro. In vivo analyses using murine xenograft models showed that this drug efficiently stimulated the differentiation of AML cells, diminished the tumor burden and metastasis, and prolonged the survival of mice. Importantly, the anti-leukemic effects of Azvudine were recapitulated in AML patient samples with various mutations, including TP53, a genetic lesion associated with adverse risk. Mechanistic studies showed that the inhibitory activity of Azvudine was directed mainly against telomerase reverse transcriptase (TERT), causing telomerase dysfunction and telomere shortening. This was accompanied by a DNA damage response, culminating in p21 upregulation and subsequent cellular differentiation in AML. In addition, increased ROS levels in the mitochondria by Azvudine modulated the Bcl-2 family proteins and promoted apoptosis, acting as a further anti-AML mechanism. Considering that telomerase-targeted therapies are currently under active clinical investigation, these compelling preclinical data justify the repositioning of Azvudine as an AML differentiation-inducing therapy.