Chemoresponse of de novo Acute Myeloid Leukemia to "7+3" Induction can Be Predicted by c-Myc-facilitated Cytogenetics.

Background: Identifying patients with de novo acute myeloid leukemia (AML) who will probably respond to the "7 + 3" induction regimen remains an unsolved clinical challenge. This study aimed to identify whether c-Myc could facilitate cytogenetics to predict a "7 + 3" induction chemoresponse in de novo AML. Methods: We stratified 75 untreated patients (24 and 51 from prospective and retrospective cohorts, respectively) with de novo AML who completed "7 + 3" induction into groups with and without complete remission (CR). We then compared Myc-associated molecular signatures between the groups in the prospective cohort after gene set enrichment analysis. The expression of c-Myc protein was assessed by immunohistochemical staining. We defined high c-Myc-immunopositivity as > 40% of bone marrow myeloblasts being c-Myc (+). Results: Significantly more Myc gene expression was found in patients who did not achieve CR by "7 + 3" induction than those who did (2439.92 ± 1868.94 vs. 951.60 ± 780.68; p = 0.047). Expression of the Myc gene and c-Myc protein were positively correlated (r = 0.495; p = 0.014). Although the non-CR group did not express more c-Myc protein than the CR group (37.81 ± 25.13% vs. 29.04 ± 19.75%; p = 0.151), c-Myc-immunopositivity could be a surrogate to predict the "7 + 3" induction chemoresponse (specificity: 81.63%). More importantly, c-Myc-immunopositivity facilitated cytogenetics to predict a "7 + 3" induction chemoresponse by increasing specificity from 91.30 to 95.92%. Conclusion: The "7 + 3" induction remains the standard of care for de novo AML patients, especially for those without a high c-Myc-immunopositivity and high-risk cytogenetics. However, different regimens might be considered for patients with high c-Myc-immunopositivity or high-risk cytogenetics.

Integrating resistance functions to predict response to induction chemotherapy in de novo acute myeloid leukemia.

OBJECTIVES: This study explored resistance functions and their interactions in de novo AML treated with the "7 + 3" induction regimen. METHODS: We analyzed RNA-sequencing profiles of whole bone marrow samples from 52 de novo AML patients who completed the "7 + 3" regimen and stratified patients into CR (n = 35) and non-CR (n = 17) groups. RESULTS: A systematic gene set analysis revealed significant associations between chemoresistance and mTOR (P < .001), myc (P < .001), mitochondrial oxidative phosphorylation (P < .001), and stemness (P = .002). These functions were independent with regard to gene contents and activity scores. An integration of these four functions showed a prediction of chemoresistance (area under the receiver operating characteristic curve = 0.815) superior to that of each function alone. Moreover, our proposed seven-gene scoring system significantly correlated with the four-function model (r = .97; P < .001) to predict chemoresistance to the "7 + 3" regimen. On multivariate analysis, a seven-gene score of ≥-0.027 (hazard ratio: 11.18; 95% confidence interval: 2.06-60.65; P = .005) was an independent risk factor for induction failure. CONCLUSIONS: Myc, OXPHOS, mTOR, and stemness were responsive for chemoresistance in AML. Treatments other than the "7 + 3" regimen need to be considered for de novo AML patients predicted to be refractory to the "7 + 3" regimen.

Mechanistic aspects of lauryl gallate-induced differentiation and apoptosis in human acute myeloid leukemia cells.

Lauryl gallate (LG) is a gallic acid derivative that has been widely used as an antioxidant food additive. In this study, we examined the anticancer effects of LG on the human acute myeloid leukemia (AML) HL60 and KG-1 cells. Our results showed that LG inhibited cell proliferation in a concentration- and time-dependent manner in both HL60 and KG-1 cells. The IC50s of LG in HL60 and KG-1 cells were 3.5 and 8.0 µM, respectively. Treatment with LG increased the proportions of annexin V-stained and sub-G1-phase HL60 and KG-1 cells. Moreover, activation of both extrinsic and intrinsic apoptotic pathways was involved in LG-induced AML cell apoptosis, accompanied by dissipation of mitochondrial membrane potential, downregulation of anti-apoptotic proteins (Bcl-2, Mcl-1, and Bcl-xL), upregulation of pro-apoptotic proteins (Bak, PUMA, DR4, and DR5), and increased caspase-2, -3, -8, and -9 activation. Our results also indicated that LG could induce monocytic differentiation in both HL60 and KG-1 cells, confirmed by morphological changes, nitroblue tetrazolium reduction assays, nonspecific esterase assays, and increased CD14 expression. After blocking LG-induced ERK and Sp1 expression using the ERK-specific inhibitor PD98059, monocytic differentiation in both HL60 and KG-1 cells decreased, suggesting that LG-induced differentiation proceeded through an ERK/Sp1 signaling axis.

Effector mechanisms of sunitinib-induced G1 cell cycle arrest, differentiation, and apoptosis in human acute myeloid leukaemia HL60 and KG-1 cells.

Acute myeloid leukaemia (AML) is a heterogeneous disease with dismal outcome. Sunitinib is an orally active inhibitor of multiple tyrosine kinase receptors approved for renal cell carcinoma and gastrointestinal stromal tumour that has also been studied for AML in several clinical trials. However, the precise mechanism of sunitinib action against AML remains unclear and requires further investigation. For this purpose, this study was conducted using human AML cell lines (HL60 and KG-1) and AML patients' mononucleated cells. Sunitinib induced G1 phase arrest associated with decreased cyclin D1, cyclin D3, and cyclin-dependent kinase (Cdk)2 and increased p27(Kip1), pRb1, and p130/Rb2 expression and phosphorylated activation of protein kinase C alpha and beta (PKCα/ß). Selective PKCα/ß inhibitor treatment abolished sunitinib-elicited AML differentiation, suggesting that PKCα/ß may underlie sunitinib-induced monocytic differentiation. Furthermore, sunitinib increased pro-apoptotic molecule expression (Bax, Bak, PUMA, Fas, FasL, DR4, and DR5) and decreased anti-apoptotic molecule expression (Bcl-2 and Mcl-1), resulting in caspase-2, caspase-3, caspase-8, and caspase-9 activation and both death receptor and mitochondria-dependent apoptosis. Taken together, these findings provide evidence that sunitinib targets AML cells through both differentiation and apoptosis pathways. More clinical studies are urgently needed to demonstrate its optimal clinical applications in AML.

An epidermal growth factor inhibitor, Gefitinib, induces apoptosis through a p53-dependent upregulation of pro-apoptotic molecules and downregulation of anti-apoptotic molecules in human lung adenocarcinoma A549 cells.

A selective epidermal growth factor receptor inhibitor, Gefitinib, has been clinically demonstrated to be effective for certain cancer cell types including lung cancer. Our previous study indicated that Gefitinib induced Fas/caspase-dependent apoptosis in human lung adenocarcinoma A549 cells. However, the pathway relaying the signals of Gefitinib-induced cell death has not been fully elucidated. Loss of normal function of p53 facilitates the development of neoplastic lesions and possibly contributes to the development of resistance to chemotherapy. Thus, the current study was designed to examine the role of p53 in Gefitinib-induced apoptosis. Incubation of human lung adenocarcinoma A549 cells with 25 microM Gefitinib resulted in phosphorylation and activation of p53 such as enhanced DNA binding activity, which was accompanied by the upregulation of PUMA (p53 upregulated modulator of apoptosis) and Fas, and downregulation of survivin and XIAP (X-linked inhibitor of apoptosis protein). The Gefitinib-mediated Fas, PUMA, survivin, XIAP regulation and subsequent apoptosis were significantly inhibited in stable p53-shRNA transfectants. Similarly, H1299/p53 cells were more sensitive to Gefitinib compared to H1299 cells in clonogenic survival assay. This event was accompanied by p53 phosphorylation, as well as Fas, PUMA, survivin, and XIAP modulation. Collectively, the results support an important role of p53 in Gefitinib-induced apoptosis in human lung cancer cells. p53 may induce apoptosis through the regulation of apoptotic (Fas and PUMA) and anti-apoptotic (XIAP and survivin) genes. Our studies not only pave a way to the understanding of pharmacological mechanisms of Gefitinib, but also implicate for the necessity to prescreen p53 expression level before clinical application of Gefitinib in human cancer therapy.

Extracellular signal-regulated kinase activation and Bcl-2 downregulation mediate apoptosis after gemcitabine treatment partly via a p53-independent pathway.

Gemcitabine is a promising compound for the treatment of human lung cancer. Although apoptosis has been shown to play a role in certain cell types with gemcitabine, the steps leading to cell death after the drug-target interaction are not well understood. We studied the molecular mechanisms of gemcitabine-induced apoptosis and determined the role of p53 function on the cytotoxic effects of gemcitabine in human nonsmall cell lung cancer (NSCLC) H1299 and H1299/p53 cells. Here, we found that gemcitabine induced an apoptotic cell death via a Bcl-2-dependent caspase-9 activation pathway. Moreover, phosphorylated activation of extracellular signal-regulated kinase (ERK) was observed upon gemcitabine treatment. Genetical or pharmacological inhibition of ERK activation markedly blocked gemcitabine-induced cell death. Furthermore, inactivation of Akt was also involved in this event. Taken together, our observations indicate that ERK activation and Akt inactivation mediated gemcitabine-induced apoptosis independently of p53 in human NSCLC H1299 cells.

Molecular mechanisms of ZD1839-induced G1-cell cycle arrest and apoptosis in human lung adenocarcinoma A549 cells.

Epithelial growth factor receptor (EGFR) has been proposed as a target for anticancer therapy. ZD1839 (Iressa) is a quinazoline derivative that selectively inhibits the EGFR tyrosine kinase activity and is under clinical use in cancer patients. However, the molecular mechanisms involved in ZD1839-mediated anticancer effects remain largely uncharacterized. In this study, exposure of human lung adenocarcinoma A549 cells to ZD1839 caused G1 arrest, and subsequently induced apoptosis. Moreover, ZD1839 increased the protein levels of p27(KIP1) and retinoblastoma-related Rb2/p130 while decreased the expression of cyclin-dependent kinase-2 (CDK2), CDK4, CDK6 and cyclin-D1, cyclin-D3. In vitro kinase assay showed that ZD1839 decreased these CDKs expression in A549 cells, leading to significantly reduce their kinase activities. In addition, ZD1839-induced death of A549 cells with characteristics of apoptosis including apoptotic morphological changes, DNA fragmentation and enhancement of TUNEL-positive cell. These events were accompanied by a marked increase of Fas protein expression, and activation of caspase-2, -3, -8. Co-treatment of cells with Fas antagonist antibody significantly blocked ZD1839-induced apoptosis. Caspase-8 and caspase-3 inhibitors, but not a caspase-9 inhibitor, were also capable of restoring cell viability. Our results indicate that downregulation of the expression and function of CDK2, CDK4, CDK6, cyclin-D1 and cyclin-D3, as well as upregulation of p27(KIP1) and pRb2/p130, are strong candidates for the cell cycle regulator that arrests ZD1839-treated A549 cells at G1 phase. Furthermore, upregulation of Fas appears to play a major role in the initiation of ZD1839-induced apoptosis, activation of caspase-8/caspase-3 cascade is involved in the execution phase of this death program.