Integration of an LPAR1 Antagonist into Liposomes Enhances Their Internalization and Tumor Accumulation in an Animal Model of Human Metastatic Breast Cancer

Promoted Translocation of Perfluorooctanoic Acid across the Blood-Retinal Barrier due to its Inhibition of Tight Junction Assembly by Antagonizing LPAR1

Eye health is becoming a significant public health concern, and a recent epidemiological investigation suggested that perfluorooctanoic acid (PFOA), a so-called forever chemical, was correlated with decreased human visual acuity; however, it remains unknown whether PFOA can pass through the blood-retinal barrier (BRB) to cause visual toxicity. In this study, the mice received a 28-day subchronic oral exposure to PFOA. The results of spatial mass spectrometry imaging indicated that the eye-enriched PFOA dispersed into the subretina primarily through the outer BRB (oBRB), which subsequently resulted in significantly increased apoptosis and decreased thickness of multiple oBRB-associated layers. BRB integrity and function were compromised due to decreased expression of the tight junction (TJ). Mechanistically, PFOA outcompeted lysophosphatidic acid to bind strongly with lysophosphatidic acid receptor 1 (LPAR1) in its antagonism, abolishing its ability to stimulate the TJ assembly-related signaling pathway. This subsequently attenuated phosphorylation of the myosin light chain, rendering insufficient contraction of the actomyosin cytoskeleton, leading to decreased TJ assembly and BRB leakage. This, in turn, facilitated PFOA translocation across the BRB and accumulation within the subretinal space. Our findings suggest that oBRB is particularly vulnerable to PFOA, which targets directly LPAR1 to disable its function of maintaining TJ assembly cascades, leading to adverse visual effects.

Effects of Lipid Headgroups on the Mechanical Properties and In Vitro Cellular Internalization of Liposomes

We performed all-atom and coarse-grained simulations of lipid bilayer mixtures of the unsaturated lipid DOPC, with saturated lipids having the same 18-carbon acyl tails and different headgroups, to understand their mechanical properties. The secondary lipids were DSPG, DSPA, DSPS, DSPC, and DSPE. The DOPC:DSPG system with 65:35 molar ratio was the softest, with area compressibility modulus KA ∼ 22% smaller than the pure DOPC value. Raising the mole % of DOPC leads to increases in KA, yet at any given composition the KA trend is DSPG < DSPA < DSPS < DSPC < DSPE. Lipid-lipid interactions are weaker in DOPC:DSPG mixtures and stronger in DSPE systems. The head and phosphate groups of the secondary lipids DSPG, DSPA, and DSPS interact strongly with salt ions. Adding secondary lipids leads to DOPC having more ordered acyl tails relative to pure DOPC systems. No evidence of phase separation or inhomogeneities was observed in our simulations. We synthesized three liposomal formulations, L-DOPC (pure DOPC) and L-DOPC/DSPG and L-DOPC/DSPA, both with 15 mol % of secondary lipid. L-DOPC/DSPA had approximately 3- and 2-times higher in vitro internalization by normal epithelial (EpH4-Ev) and metastatic breast cancer (4T1) cells, compared with L-DOPC. The uptake of L-DOPC/DSPG by EpH4-Ev cells was almost 2-fold compared to L-DOPC, but both liposomes had similar uptakes by cancer cells. As L-DOPC/DSPG and L-DOPC/DSPA have similar KA values, we presumed that the mechanical properties, possibly in combination with the higher negative surface charges in L-DOPC/DSPA and differences in effective liposome diameters and diffusivities, contributed to these observations.

The immunological landscape and silico analysis of key paraptosis regulator LPAR1 in gastric cancer patients

This study aims to identify key regulators of paraptosis in gastric cancer (GC) and explore their potential in guiding therapeutic strategies, especially in stomach adenocarcinoma (STAD). Genes associated with paraptosis were identified from the references and subjected to Cox regression analysis in the TCGA-STAD cohort. Using machine learning models, LPAR1 consistently ranked highest in feature importance. Multiple sequencing data showed that LPAR1 was significantly overexpressed in cancer-associated fibroblasts (CAFs). LPAR1 expression was significantly higher in normal tissues, and ROC analysis demonstrated its discriminative ability. Copy number alterations and microsatellite instability were significantly associated with LPAR1 expression. High LPAR1 expression correlated with advanced tumor grades and specific cancer immune subtypes, and multivariate analysis confirmed LPAR1 as an independent predictor of poor prognosis. LPAR1 expression was associated with different immune response metrics, including immune effector activation and upregulated chemokine secretion. High LPAR1 expression also correlated with increased sensitivity to compounds, such as BET bromodomain inhibitors I-BET151 and RITA, suggesting LPAR1 as a biomarker for predicting drug activity. FOXP2 showed a strong positive correlation with LPAR1 transcriptional regulation, while increased methylation of LPAR1 promoter regions was negatively correlated with gene expression. Knockdown of LPAR1 affected cell growth in most tumor cell lines, and in vitro experiments demonstrated that LPAR1 influenced extracellular matrix (ECM) contraction and cell viability in the paraptosis of CAFs. These findings suggest that LPAR1 is a critical regulator of paraptosis in GC and a potential biomarker for drug sensitivity and immunotherapy response. This underscores the role of CAFs in mediating tumorigenic effects and suggests that targeting LPAR1 could be a promising strategy for precision medicine in GC.

The Emerging Role of LPA as an Oncometabolite

Lysophosphatidic acid (LPA) is a phospholipid that displays potent signalling activities that are regulated in both an autocrine and paracrine manner. It can be found both extra- and intracellularly, where it interacts with different receptors to activate signalling pathways that regulate a plethora of cellular processes, including mitosis, proliferation and migration. LPA metabolism is complex, and its biosynthesis and catabolism are under tight control to ensure proper LPA levels in the body. In cancer patient specimens, LPA levels are frequently higher compared to those of healthy individuals and often correlate with poor responses and more aggressive disease. Accordingly, LPA, through promoting cancer cell migration and invasion, enhances the metastasis and dissemination of tumour cells. In this review, we summarise the role of LPA in the regulation of critical aspects of tumour biology and further discuss the available pre-clinical and clinical evidence regarding the feasibility and efficacy of targeting LPA metabolism for effective anticancer therapy.

Association of ESR1 germline variants with TP53 somatic variants in breast tumors in a genome-wide study

Background

In breast tumors, somatic mutation frequencies in TP53 and PIK3CA vary by tumor subtype and ancestry. HER2 positive and triple negative breast cancers (TNBC) have a higher frequency of TP53 somatic mutations than other subtypes. PIK3CA mutations are more frequently observed in hormone receptor positive tumors. Emerging data suggest tumor mutation status is associated with germline variants and genetic ancestry. We aimed to identify germline variants that are associated with somatic TP53 or PIK3CA mutation status in breast tumors.

Methods

A genome-wide association study was conducted using breast cancer mutation status of TP53 and PIK3CA and functional mutation categories including TP53 gain of function (GOF) and loss of function mutations and PIK3CA activating/hotspot mutations. The discovery analysis consisted of 2850 European ancestry women from three datasets. Germline variants showing evidence of association with somatic mutations were selected for validation analyses based on predicted function, allele frequency, and proximity to known cancer genes or risk loci. Candidate variants were assessed for association with mutation status in a multi-ancestry validation study, a Malaysian study, and a study of African American/Black women with TNBC.

Results

The discovery Germline x Mutation (GxM) association study found five variants associated with one or more TP53 phenotypes with P values <1×10-6, 33 variants associated with one or more TP53 phenotypes with P values <1×10-5, and 44 variants associated with one or more PIK3CA phenotypes with P values <1×10-5. In the multi-ancestry and Malaysian validation studies, germline ESR1 locus variant, rs9383938, was associated with the presence of TP53 mutations overall (P values 6.8×10-5 and 9.8×10-8, respectively) and TP53 GOF mutations (P value 8.4×10-6). Multiple variants showed suggestive evidence of association with PIK3CA mutation status in the validation studies, but none were significant after correction for multiple comparisons.

Conclusions

We found evidence that germline variants were associated with TP53 and PIK3CA mutation status in breast cancers. Variants near the estrogen receptor alpha gene, ESR1, were significantly associated with overall TP53 mutations and GOF mutations. Larger multi-ancestry studies are needed to confirm these findings and determine if these variants contribute to ancestry-specific differences in mutation frequency.