ATF4 renders human T-cell acute lymphoblastic leukemia cell resistance to FGFR1 inhibitors through amino acid metabolic reprogramming

Abnormalities of FGFR1 have been reported in multiple malignancies, suggesting FGFR1 as a potential target for precision treatment, but drug resistance remains a formidable obstacle. In this study, we explored whether FGFR1 acted a therapeutic target in human T-cell acute lymphoblastic leukemia (T-ALL) and the molecular mechanisms underlying T-ALL cell resistance to FGFR1 inhibitors. We showed that FGFR1 was significantly upregulated in human T-ALL and inversely correlated with the prognosis of patients. Knockdown of FGFR1 suppressed T-ALL growth and progression both in vitro and in vivo. However, the T-ALL cells were resistant to FGFR1 inhibitors AZD4547 and PD-166866 even though FGFR1 signaling was specifically inhibited in the early stage. Mechanistically, we found that FGFR1 inhibitors markedly increased the expression of ATF4, which was a major initiator for T-ALL resistance to FGFR1 inhibitors. We further revealed that FGFR1 inhibitors induced expression of ATF4 through enhancing chromatin accessibility combined with translational activation via the GCN2-eIF2α pathway. Subsequently, ATF4 remodeled the amino acid metabolism by stimulating the expression of multiple metabolic genes ASNS, ASS1, PHGDH and SLC1A5, maintaining the activation of mTORC1, which contributed to the drug resistance in T-ALL cells. Targeting FGFR1 and mTOR exhibited synergistically anti-leukemic efficacy. These results reveal that FGFR1 is a potential therapeutic target in human T-ALL, and ATF4-mediated amino acid metabolic reprogramming contributes to the FGFR1 inhibitor resistance. Synergistically inhibiting FGFR1 and mTOR can overcome this obstacle in T-ALL therapy.

[Analysis of diagnosis, treatment and risk classification of blunt thoracic aortic injury]

Objective: Propose a new risk classification system for blunt thoracic aortic injury and explore its treatment strategies. Methods: After the retrospective analysis of clinical data from 68 patients with blunt thoracic aortic injury in the First Affiliated Hospital of Zhengzhou University from November 2016 to October 2020, there were 56 males and 12 females, among these patients, the median age was 45(21-69). According to the degree of aortic injury and the combined injury, the patients were scored for aortic injury, and the risk of the patients were graded into following three types: low-risk group (score ≤ 2 points) 12 cases, intermediate-risk group (3 points ≤ score ≤ 5 points) 41 cases, high-risk group (score ≥ 6 points) 15 cases. Analyzing the effects of treatments received by patients in different grades on the prognosis. Patients were followed up through hospitalization or outpatient clinics at 1, 3, 6, 12 months after surgery and every year thereafter. Results: Of the 68 patients, 21 received non-surgical treatment and 47 received surgical repair, including 6 open surgery and 41 thoracic aortic endovascular repair. There were 16 cases of emergency operation and 31 cases of delayed operation. Twelve low-risk patients were treated with non-surgical treatment, and only 1 patient died of lung infection, with a mortality rate of 8.3% (1/12). There were 8 deaths in 41 moderate-risk patients, with a mortality rate of 19.5% (8/41), and the aortic-related mortality rate was 9.8% (4/41), and the operative mortality rate was 10.8% (4/37). The total mortality of 15 high-risk patients was 40% (6/15), and the aortic-related mortality rate was 30.0% (5/15), and the mortality rate of surgical patients was 10% (1/10). During the follow-up period of 5 to 52 months, no deaths occurred outside the hospital. According to the risk grading, there were significant differences in the aortic-related mortality of each grade (χ²=7.840, P=0.020). During the follow-up of 5-52 months, 1 case had type Ⅰ endoleak, 1 case of cerebral infarction, and 1 case of acute renal failure. Conclusion: According to the patient's degree of aortic injury and combined injury, the risk classification helps to choose the appropriate treatment.