Higher genetically predicted low-density lipoprotein levels increase the renal cancer risk independent of triglycerides and high-density lipoprotein levels: A Mendelian randomization study

The causation between lipids and renal cancer remains inconclusive. Our purpose is to explore the causal relationships between the three primary lipid metabolism-related substances, namely triglycerides (TG), low-density lipoprotein (LDL) and high-density lipoprotein (HDL) with the risk of renal cancer using Mendelian randomization (MR) methods. Genetic instruments for lipids were acquired from the UK Biobank. Outcome data were from the FinnGen study (1397 renal cancer cases and 204 070). Single-variable MR (SVMR) and multi-variable MR (MVMR) analyses were conducted with TwoSampleMR package based on R 4.0.3. The random-effect inverse-variance weighted (IVW), MR-Egger, weighted-median method, and weighted mode were the four main computing methods. We found that per 1 SD elevated LDL level was causally associated with renal cancer occurrence based on SVMR (OR, 1.31, 95% CI: 1.05-1.64, P = .016). Similar significant associations were found in other methods. However, the results of SVMR did not support significant associations between TG, and HDL with renal cancer risk in all methods. The association between LDL and renal cancer was still significant in MVMR analysis (OR for IVW method: 1.22 per 1 SD higher trait (SD, 95% CI: 1.11-1.34, P < .001; OR for MR-Egger: 1.22 per 1 SD higher trait, 95% CI: 1.01-1.47, P = .042) when taking TG and HDL into consideration. Our study supported that elevated serum LDL levels is causally associated with an increased risk of renal cancer independent of TG and HDL.

Involvement of LDL and ox-LDL in Cancer Development and Its Therapeutical Potential

Lipid metabolism disorder is related to an increased risk of tumorigenesis and is involved in the rapid growth of cancer cells as well as the formation of metastatic lesions. Epidemiological studies have demonstrated that low-density lipoprotein (LDL) and oxidized low-density lipoprotein (ox-LDL) are closely associated with breast cancer, colorectal cancer, pancreatic cancer, and other malignancies, suggesting that LDL and ox-LDL play important roles during the occurrence and development of cancers. LDL can deliver cholesterol into cancer cells after binding to LDL receptor (LDLR). Activation of PI3K/Akt/mTOR signaling pathway induces transcription of the sterol regulatory element-binding proteins (SREBPs), which subsequently promotes cholesterol uptake and synthesis to meet the demand of cancer cells. Ox-LDL binds to the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and cluster of differentiation 36 (CD36) to induce mutations, resulting in inflammation, cell proliferation, and metastasis of cancer. Classic lipid-lowering drugs, statins, have been shown to reduce LDL levels in certain types of cancer. As LDL and ox-LDL play complicated roles in cancers, the potential therapeutic effect of targeting lipid metabolism in cancer therapy warrants more investigation.

Lipoproteins and cancer: The role of HDL-C, LDL-C, and cholesterol-lowering drugs

Cholesterol is an amphipathic sterol molecule that is vital for maintaining normal physiological homeostasis. It is a relatively complicated molecule with 27 carbons whose synthesis starts with 2-carbon units. This in itself signifies the importance of this molecule. Cholesterol serves as a precursor for vitamin D, bile acids, and hormones, including estrogens, androgens, progestogens, and corticosteroids. Although essential, high cholesterol levels are associated with cardiovascular and kidney diseases and cancer initiation, progression, and metastasis. Although there are some contrary reports, current literature suggests a positive association between serum cholesterol levels and the risk and extent of cancer development. In this review, we first present a brief overview of cholesterol biosynthesis and its transport, then elucidate the role of cholesterol in the progression of some cancers. Suggested mechanisms for cholesterol-mediated cancer progression are plentiful and include the activation of oncogenic signaling pathways and the induction of oxidative stress, among others. The specific roles of the lipoprotein molecules, high-density lipoprotein (HDL) and low-density lipoprotein (LDL), in this pathogenesis, are also reviewed. Finally, we hone on the potential role of some cholesterol-lowering medications in cancer.

Endocrine Disruptors and Prostate Cancer

The role of endocrine disruptors (EDs) in the human prostate gland is an overlooked issue even though the prostate is essential for male fertility. From experimental models, it is known that EDs can influence several molecular mechanisms involved in prostate homeostasis and diseases, including prostate cancer (PCa), one of the most common cancers in the male, whose onset and progression is characterized by the deregulation of several cellular pathways including androgen receptor (AR) signaling. The prostate gland essentiality relies on its function to produce and secrete the prostatic fluid, a component of the seminal fluid, needed to keep alive and functional sperms upon ejaculation. In physiological condition, in the prostate epithelium the more-active androgen, the 5α-dihydrotestosterone (DHT), formed from testosterone (T) by the 5α-reductase enzyme (SRD5A), binds to AR and, upon homodimerization and nuclear translocation, recognizes the promoter of target genes modulating them. In pathological conditions, AR mutations and/or less specific AR binding by ligands modulate differently targeted genes leading to an altered regulation of cell proliferation and triggering PCa onset and development. EDs acting on the AR-dependent signaling within the prostate gland can contribute to the PCa onset and to exacerbating its development.

Oxidised low-density lipoprotein, a possible distinguishing lipid profile biomolecule between prostate cancer and benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) and prostate cancer (PCa) share common conditions such as lower urinary tract symptoms (LUTS) and dyslipidaemia. Whether an extensive lipid profile analysis could discriminate between BPH and PCa was the objective. Thirty-six (36) BPH and twenty (20) PCa outpatients of a urology clinic plus forty (40) controls without LUTS, but normal PSA, were recruited. Body mass index (BMI), lipid profile (total cholesterol [CHOL], triglycerides [TG], high-density lipoprotein [HDL], very-low-density lipoprotein [VLDL], low-density lipoprotein [LDL] and Castelli's risk index I [CR I] [TC/HDL]), oxidised LDL, apolipoprotein E, ceramide and PSA were determined. Mean ages for BPH, PCa and control were 69 ± 13, 67 ± 10 and 53 ± 7 years respectively. Most parameters apart from BMI and HDL were significantly different compared to the control group. oxLDL for BPH versus control, PCa versus control and BPH versus PCa was significant (p < 0.001, p = 0.02 and p < 0.001 respectively). Ceramide showed significant group differences. Between BPH and PCa, total cholesterol, LDL and Apo E were significantly different (p = 0.00, p = 0.01 and p = 0.03 respectively). Apo E could potentially be a discriminating biomarker. Receiver operating characteristic curves for TPSA, Apo E and oxLDL demonstrated sensitivity of 69.44 and specificity of 88.24 for oxLDL, hence more discriminatory.

BMI and serum lipid parameters predict increasing risk and aggressive prostate cancer in Chinese people

OBJECTIVES

To determine if obesity and serum lipid parameters are associated with increased risk and more aggressive prostate cancer in Chinese population.

MATERIALS AND METHODS

We conducted a retrospective cohort analysis including 3102 patients. Kruskal-Wallis test for continuous variables and the chi-squared tests for categorical variables were used for univariate comparison of the differences in patient characteristics across BMI categories between different groups. Odds ratios (OR) and 95% confidence intervals (CI) were estimated for the association between prostate cancer and the various patient characteristics. Multivariable Cox proportional hazards regression was performed to assess the risk of prostate cancer recurrence.

RESULTS

974 consecutive men were diagnosed as prostate cancer and 700 patients subsequently received radical prostatectomy immediately, and 1031 patients were pathologically diagnosed as biopsy negative. The level of low-density-lipoprotein cholesterol (LDL-c) and total cholesterol was significantly higher and the high-density-lipoprotein cholesterol (HDL-c) level is much lower in prostate cancer patients. Patients with low level of HDL-c, who subsequently received radical prostatectomy, had increased risk of high risk disease. In addition, patients with normal weight were less likely to develop a biochemical recurrence. Combined analysis revealed that obese patients had significantly higher rates of PSA recurrence over time than nonobese patients.

CONCLUSIONS

In our study, lipid parameters are supposed to be associated with prostate cancer risk and aggressiveness. Obese men are at increased risk of PSA recurrence after radical prostatectomy.

Investigating the Incidence of Prostate Cancer in Iran 2005 -2008 using Bayesian Spatial Ecological Regression Models

BACKGROUND

Prostate cancer is the most commonly diagnosed form of cancer and the sixth leading cause of cancer-related deaths among men in the entire world. Reported standardized incidence rates are 12.6, 61.7, 11.9 and 27.9 in Iran, developed countries, developing countries and the entire world, respectively. The present study investigated the relative risk of PC in Iran at the province level and also explored the impact of some factors by the use of Bayesian models.

MATERIALS AND METHODS

Our study population was all men with PC in Iran from 2005 to 2008. Considered risk factors were smoking, fruit and vegetable intake, physical activity, obesity and human development index. We used empirical and full Bayesian models to study the relative risk in Iran at province level to estimate the risk of PC more accurately.

RESULTS

In Iran from 2005 to 2008 the total number of known PC cases was 10,361 with most cases found in Fars and Tehran and the least in Ilam. In all models just human development index was found to be significantly related to PC risk Conclusions: In the unadjusted model, Fars, Semnam, Isfahan and Tehran provinces have the highest and Sistan-and-Baluchestan has the least risk of PC. In general, central provinces have high risk. After adjusting for covariates, Fars and Zanjan provinces have the highest relative risk and Kerman, Northern Khorasan, Kohgiluyeh Boyer Ahmad, Ghazvin and Kermanshah have the lowest relative risk. According to the results, the incidence of PC in provinces with higher human development index is higher.

Conditional PTEN-deficient mice as a prostate cancer chemoprevention model

BACKGROUND

We generated a mouse model of prostate cancer based on the adult-prostate-specific inactivation of phosphatase and tensin homolog (PTEN) using the Cre-loxP system. The potential of our mice as a useful animal model was examined by evaluating the chemopreventive efficacy of the anti-androgen, chlormadinone acetate (CMA).

MATERIALS AND METHODS

Six-week-old mice were treated subcutaneously with 50 μg/g of CMA three times a week for 9 or 14 weeks and sacrificed at weeks 15 and 20. Macroscopic change of the entire genitourinary tract (GUT) and histologically evident prostate gland tumor development were evaluated. Proliferation and apoptosis status in the prostate were examined by immunohistochemistry.

RESULTS

CMA triggered significant shrinkage of not only the GUT but also prostate glands at 15 weeks compared to the control (p=0.017 and p=0.010, respectively), and the trend became more marked after a further five-weeks of treatment. The onset of prostate adenocarcinoma was not prevented but the proliferation of cancer cells was inhibited by CMA, which suggested the androgen axis is critical for cancer growth in these mice.

CONCLUSIONS

Conditional PTEN-deficient mice are useful as a preclinical model for chemoprevention studies and serve as a valuable tool for the future screening of potential chemopreventive agents.