Atypical plasma lipid profiles in leukemia

Lipid profile as a novel prognostic predictor for patients with acute myeloid leukemia

Purpose

This study investigated the relationship between serum lipid levels and clinical outcomes in acute myeloid leukemia (AML) by establishing a predictive risk classification model.

Method

A total of 214 AML patients who were pathologically diagnosed and treated with standard induction chemotherapy at Sun Yat-Sen University Cancer Center were included. The patients were randomly divided into the training (n = 107) and validation (n=107) cohorts. Univariate and multivariate Cox analyses were used to assess the value of triglyceride (TG), Apolipoprotein B (Apo B), Apo Apolipoprotein A-I (Apo A-I), cholesterol (CHO), and high-density lipoprotein (HDL) as prognostic factors for AML.

Results

After a series of data analyses, a five-factor model was established to divide the patients into high- and low-risk groups. Kaplan-Meier survival analysis showed that the high-risk group had a poor prognosis (P<0.05). The area under the curve of the novel model for five-year OS was 0.737. A nomogram was constructed to integrate the model with age and the 2017 ELN cytogenetic classification, with the merged model showing improved accuracy with an area under the curve of 0.987 for five-year OS.

Conclusion

A novel model was constructed using a combination of the serum lipid profile and clinical characteristics of AML patients to enhance the predictive accuracy of clinical outcomes. The nomogram used the lipid profile which is routinely tested in clinical blood biochemistry and showed both specific prognostic and therapeutic potential.

Is low cholesterol a risk factor for cancer mortality?

Although a large number of studies have shown the associations of high plasma lipid profile levels with cancer, few studies demonstrate the association between low serum cholesterol (<160 mg/dl) and risk for cancer mortality. The aim of this study was to determine the association of low serum cholesterol level as a risk factor for mortality in cancer. The prospective cohort studies were conducted on 19 of 52 cohort studies including 30 179 male and 26 005 female participants who were followed up for 9 years. Cox proportion hazard model was applied to analyze these data. The associations are presented as hazard ratios (HRs) with 95% confidence intervals (CI). The statistical package for the social sciences software was used for analysis. The multivariate analysis results showed risk associations with low serum cholesterol for the first decile among male participants (cancer: HR=1.52, 95% CI: 1.06-2.18; noncancer liver dysfunction: HR=10.73, 95% CI: 3.74-30.18) and female participants (cancer: HR=1.03, 95% CI: 0.52-2.05; noncancer liver dysfunction: HR=25.8, 95% CI: 3.09-217.70). Furthermore, in the second decile, this association among male patients (noncancer liver dysfunction: HR=3.73, 95% CI: 1.16-11.95) had a statistically significant result. For the remaining deciles in both sexes, cancer and noncancer liver dysfunction has some risk or protective association, although not significant. Findings of this study indicated an inverse association between low serum cholesterol and cancer and noncancer liver dysfunction mortality.

Leukemia cells display lower levels of intracellular cholesterol irrespective of the exogenous cholesterol availability

BACKGROUND

Different types of cancer cells are previously shown to accumulate intracellular cholesterol. However, the data on intracellular cholesterol levels in leukemia cells provide contradictory evidence. Various previous works indicate either increase, decrease or no difference in total cholesterol levels between leukemia cells and healthy peripheral blood mononuclear cells (PBMCs).

METHODS

We studied the intracellular cholesterol levels in acute myeloid leukemia (AML) and acute lymphocytic leukemia (ALL) cells and compared with that in PBMCs from the healthy subjects.

RESULTS

We observed that the PBMCs from AML (n=7) and ALL (n=7) patients displayed significantly lower intracellular levels of total cholesterol in comparison to PBMCs from the healthy subjects (n=26). Consistent with the patient data the ALL (CCRF-CEM and MOLT-3) and AML (KG-1 and THP-1) cell lines also displayed significantly lower intracellular levels of total cholesterol. We confirmed this observation using multiple methodological approaches. Both ALL and AML cell lines also displayed significantly lower levels of free cholesterol and cholesteryl ester contents in comparison to normal hematopoietic cells. We observed that >90% of the total cholesterol in leukemia cells as well as in normal PBMCs was present in the form of cholesteryl esters. It was also observed that the lower levels of cholesterol in leukemia cells are not affected by exogenous cholesterol availability.

CONCLUSIONS

Present study provides convincing evidence to prove that the cellular free cholesterol and cholesteryl ester content is significantly reduced in leukemia cells in comparison to normal hematopoietic cells in circulation. Moreover, it was shown that the lower levels of cholesterol in leukemia cells are not affected by exogenous cholesterol availability.