Cholesterol reprograms glucose and lipid metabolism to promote proliferation in colon cancer cells

Expression of the cholesterol transporter SR-B1 in melanoma cells facilitates inflammatory signaling leading to reduced cholesterol synthesis

Scavenger receptor class B type 1 (SR-B1) is a cholesterol transporter, abundantly expressed in human melanoma, yet its precise role for melanoma progression is not fully understood. This study investigates the involvement of SR-B1 in cholesterol homeostasis of tumor cells and its implications for potential therapy. We found that SR-B1 depletion in melanoma cells does not alter total cholesterol levels, but induces cholesterol biosynthesis. This effect was characterized by an increased expression of HMG-CoA reductase (HMGCR), a rate limiting enzyme of cholesterol biosynthesis. Notably, further analyses indicated that this regulation occurs at the post-translational level, mediated via the hypoxia-inducible factor (HIF) signaling pathway. Importantly, we identified SR-B1 as a transporter of the lipid hormone sphingosine-1-phosphate (S1P) and we found that S1P exposure leads to HIF1A up-regulation. Finally, we used a pluripotent stem cell-derived skin organoid model to show that targeting SR-B1 in combination with targeted melanoma therapy can lead to increased apoptosis and suppressed proliferation of transplanted tumor cells. Our study shows that functional SR-B1 is linked to inflammatory signaling, which reduces cholesterol synthesis, while enabling melanoma cell survival during chemotherapy treatment.

Research progress on cholesterol metabolism and tumor therapy

Cholesterol and its metabolic derivatives have important biological functions and are crucial in tumor initiation, progression, and treatment. Cholesterol maintains the physical properties of cellular membranes and is pivotal in cell signal transduction. Cholesterol metabolism includes both de novo synthesis and uptake from extracellular sources such as low-density lipoprotein (LDL) and high-density lipoprotein (HDL). This review explores both aspects to provide a comprehensive understanding of their roles in cancer. Cholesterol metabolism is involved in bile acid production and steroid hormone biosynthesis and is closely linked to the reprogramming of endogenous and exogenous cellular signals within the tumor microenvironment. These signals are intricately associated with key biological processes such as tumor cell proliferation, survival, invasion, and metastasis. Evidence suggests that regulating cholesterol metabolism may offer therapeutic benefits by inhibiting tumor growth, remodeling the immune microenvironment, and enhancing antitumor immune responses. This review summarizes the role of cholesterol metabolism in tumor biology and discusses the application of statins and other cholesterol metabolism inhibitors in cancer therapy, aiming to provide novel insights for the development of antitumor drugs targeting cholesterol metabolism and for advances in cancer diagnosis and treatment.

Low-Density Lipoprotein (LDL) is Associated with Earlier Progression in Synchronous Metastatic Colorectal Cancer Treated without Curative Intent

BACKGROUND

Low-density lipoprotein cholesterol (LDL) is associated with the occurrence of colorectal cancer (CRC). This study aims to investigate its prognostic role and associated clinicopathological factors in the metastatic setting.

METHODS

Patients with newly diagnosed synchronous metastatic CRC were included. Patients were grouped according to the serum LDL levels at the diagnosis (≤ 130 mg/dL: Normal-LDL, > 130 mg/dL: High-LDL). LDL-associated clinicopathological factors, progression-free survival (PFS), and overall survival (OS) were assessed.

RESULTS

A total of 90 patients were included. 44.4% (n = 40) was in the normal-LDL and 56.6% (n = 50) in the high-LDL group. Colonic localization of the primary tumor was more frequent in the high-LDL group (90% vs. 67.5%, p = 0.009). The high-LDL group more frequently had local treatments [metastasectomy (26% vs. 2.5%, p = 0.002) and embolization-ablation (38% vs. 17.5%, p = 0.033)]. Despite higher curative intent with local treatments in the high-LDL group, PFS [10.03 months (95% Confidence Interval (CI):6.97-14.77) vs 9.63 mo. (95% CI: 7.93-14.00), p = 0.872] and OS [20.87 mo. (95% CI: 14.87-36.47) vs. 17.63 mo. (95% CI: 14.30-43.03), p = 0.925] did not differ from the normal-LDL. Among patients treated without any curative intent, high LDL was associated with significantly worse PFS [4.97 mo. (95% CI: 3.00-7.73) vs. 8.43 mo. (95% CI: 6.10-9.90), p = 0.048].

CONCLUSION

This study suggests that serum LDL is associated with colonic primary localization in synchronous metastatic CRC. Levels > 130 mg/dL at diagnosis may be associated with worse survival and may be further investigated as a biomarker. Larger, multicenter and prospective studies are needed.

Association analysis of gut microbiota with LDL-C metabolism and microbial pathogenicity in colorectal cancer patients

BACKGROUND

Colorectal cancer (CRC) is the most common gastrointestinal malignancy worldwide, with obesity-induced lipid metabolism disorders playing a crucial role in its progression. A complex connection exists between gut microbiota and the development of intestinal tumors through the microbiota metabolite pathway. Metabolic disorders frequently alter the gut microbiome, impairing immune and cellular functions and hastening cancer progression.

METHODS

This study thoroughly examined the gut microbiota through 16S rRNA sequencing of fecal samples from 181 CRC patients, integrating preoperative Low-density lipoprotein cholesterol (LDL-C) levels and RNA sequencing data. The study includes a comparison of microbial diversity, differential microbiological analysis, exploration of the associations between microbiota, tumor microenvironment immune cells, and immune genes, enrichment analysis of potential biological functions of microbe-related host genes, and the prediction of LDL-C status through microorganisms.

RESULTS

The analysis revealed that differences in α and β diversity indices of intestinal microbiota in CRC patients were not statistically significant across different LDL-C metabolic states. Patients exhibited varying LDL-C metabolic conditions, leading to a bifurcation of their gut microbiota into two distinct clusters. Patients with LDL-C metabolic irregularities had higher concentrations of twelve gut microbiota, which were linked to various immune cells and immune-related genes, influencing tumor immunity. Under normal LDL-C metabolic conditions, the protective microorganism Anaerostipes_caccae was significantly negatively correlated with the GO Biological Process pathway involved in the negative regulation of the unfolded protein response in the endoplasmic reticulum. Both XGBoost and MLP models, developed using differential gut microbiota, could forecast LDL-C levels in CRC patients biologically.

CONCLUSIONS

The intestinal microbiota in CRC patients influences the LDL-C metabolic status. With elevated LDL-C levels, gut microbiota can regulate the function of immune cells and gene expression within the tumor microenvironment, affecting cancer-related pathways and promoting CRC progression. LDL-C and its associated gut microbiota could provide non-invasive markers for clinical evaluation and treatment of CRC patients.

The role of cholesterol metabolism in lung cancer

Elevated serum cholesterol metabolism is associated with a reduced risk of lung cancer. Disrupted cholesterol metabolism is evident in both lung cancer patients and tumor cells. Inhibiting tumor cell cholesterol uptake or biosynthesis pathways, through the modulation of receptors and enzymes such as liver X receptor and sterol-regulatory element binding protein 2, effectively restrains lung tumor growth. Similarly, promoting cholesterol excretion yields comparable effects. Cholesterol metabolites, including oxysterols and isoprenoids, play a crucial role in regulating cholesterol metabolism within tumor cells, consequently impacting cancer progression. In lung cancer patients, both the cholesterol levels in the tumor microenvironment and within tumor cells significantly influence cell growth, proliferation, and metastasis. The effects of cholesterol metabolism are further mediated by the reprogramming of immune cells such as T cells, B cells, macrophages, myeloid-derived suppressor cells, among others. Ongoing research is investigating drugs targeting cholesterol metabolism for clinical treatments. Statins, targeting the cholesterol biosynthesis pathway, are widely employed in lung cancer treatment, either as standalone agents or in combination with other drugs. Additionally, drugs focusing on cholesterol transportation have shown promise as effective therapies for lung cancer. In this review, we summarized current research regarding the rule of cholesterol metabolism and therapeutic advances in lung cancer.

The combined characteristics of cholesterol metabolism and the immune microenvironment may serve as valuable biomarkers for both the prognosis and treatment of hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) being a complex disease, commonly exhibits multifaceted presentations, rendering its treatment challenging and necessitating specific approaches. The tumor immune microenvironment is crucial in cancer treatment, and cholesterol metabolism is a key component that helps cells grow and produce vital metabolites. However, the reprogramming of cholesterol metabolism in the tumor microenvironment (TME) can promote HCC development, and cancer classifiers relating to cholesterol metabolism are currently limited. Despite significant progress, further research is needed to improve early detection, liver function, and treatment options to improve patient outcomes.

Methods

To evaluate the expression abundance of tumor immune microenvironment (TIME) and cholesterol metabolism in 8 types of liver cancer cells, we comprehensively evaluated the immune cell composition, extracellular matrix alterations, and activity of relevant signaling pathways in the TIME through nine liver cancer patients, stromal scoring, immune scoring, tumor purity scoring, immune infiltration analysis, and pathway enrichment. Subsequently, we utilized machine learning techniques to construct prognostic models for both cholesterol metabolism and the tumor immune microenvironment, further exploring the tumor mutation burden, immune infiltration levels, and drug sensitivity in different subtypes of HCC patients.

Results

Our study constructed three cancer screening models to identify HCC patients with high cholesterol metabolism and low TIME, who have a poorer prognosis. On the contrary, patients with low cholesterol metabolism and high TIME often have better prognosis. Furthermore, we identified chemical compounds, such as BPD-00008900, ML323, Doramapimod, and AZD2014, which display better chemotherapy results for high-risk patients in specific sub-groups.