Blood Lipid Concentrations and Colorectal Adenomas: A Systematic Review and Meta-Analysis of Colonoscopy Studies in Asia, 2000-2014

Association of Helicobacter pylori infection with colorectal polyps/adenomas: A single-center cross-sectional study

BACKGROUND

Helicobacter pylori (H. pylori) infection may be associated with colorectal polyps/adenomas, but the current evidence remains controversial.

METHODS

We retrospectively screened the medical records of 655 participants who underwent both colonoscopy and H. pylori test from June 15, 2020 to April 30, 2023. The number, size, location, and pathological type of colorectal polyps/adenomas were compared between H. pylori positive and negative groups. Adjusting for age, gender, smoking, drinking, hypertension, diabetes, fatty liver, body mass index, and inflammatory and metabolic indicators, multivariate logistic regression analyses were performed to evaluate the association of H. pylori infection with the number, size, location, and pathological type of colorectal polyps/adenomas, where no polyp/adenoma was used as reference.

RESULTS

Overall, 508 participants were included, of whom 154 and 354 were divided into H. pylori positive and negative groups, respectively. H. pylori positive group had significantly higher colorectal polyps/adenomas (74.7 % vs. 65.8 %, P=0.048), low-grade adenomas (55.7 % vs. 47.6 %, P=0.026), advanced adenomas (22.6 % vs. 13.3 %, P=0.008), and colorectal polyps/adenomas with sizes of ≥6 mm (61.7 % vs. 48.5 %, P=0.002) and ≥10 mm (25.2 % vs. 14.6 %, P=0.004) than H. pylori negative group. In multivariate logistic regression analyses, H. pylori infection was independently associated with low-grade adenomas (OR=2.677, 95 %CI=1.283-5.587, P=0.009), advanced adenomas (OR=3.017, 95 %CI=1.007-9.036, P=0.049), right-side colon polyps/adenomas (OR=5.553, 95 %CI=1.679-18.360, P=0.005), and colorectal polyps/adenomas with sizes of ≥10 mm (OR=4.436, 95 %CI=1.478-13.310, P=0.008), but not number of colorectal polyps/adenomas.

CONCLUSION

H. pylori infection is associated with increased risk of colorectal polyps/adenomas, especially low-grade adenomas, advanced adenomas, right-side colon polyps/adenomas, and large colorectal polyps/adenomas.

The role of BMI, serum lipid profile molecules and their derivative indexes in colorectal polyps

Objectives

To investigate the role of body mass index (BMI), serum lipid profile molecules and their derivative indexes in colorectal polyps.

Methods

A total of 352 individuals who underwent colonoscopy at our center were included in this retrospective analysis. Of these, 247 patients without evident abnormalities (control group), while 105 patients diagnosed with colorectal polyps (patient group). Serum lipid profile molecules and their derivative indexes were then compared between the two groups.

Results

The patient group exhibited significantly higher levels of total cholesterol (TC) and apolipoprotein B (ApoB) compared to the control group (p<0.05). In males, the patient group displayed elevated levels of ApoB and ApoB/ApoA1 ratio compared to the control group (p<0.05). Additionally, the triglycerides (TG) and TG/high-density lipoprotein-cholesterol (HDL-C) ratios were significantly higher in the multiple polyps group than in the single polyp group (p<0.05). Furthermore, the HDL-C and HDL-C/ApoA1 ratio levels were higher in the adenomatous polyp group when compared to the non-adenomatous polyp group (p<0.05). Multiple logistic regression analysis indicated that total cholesterol (TC), TG, low-density lipoprotein-cholesterol (LDL-C), TC/HDL-C ratio, TG/HDL-C ratio and LDL-C/HDL-C ratio were risk factors for the occurrence of colorectal polyps (p<0.05). ROC curve analyses revealed that TC, ApoB, and ApoB/ApoA1 ratio were associated with colorectal polyps. No significant difference in BMI between the two groups (p>0.05).

Conclusions

The incidence and progression of colorectal polyps are linked to serum lipid molecules and their derivative indexes. Dyslipidemia may increase the risk of colorectal polyps, potentially leading to colorectal cancer (CRC).

El papel del IMC, las moléculas del perfil lipídico sérico y sus índices derivados en los pólipos colorrectales

Objetivos

Investigar el papel del IMC, las moléculas del perfil lipídico en suero y los cocientes lipoproteicos en los pólipos colorrectales.

Métodos

En un análisis retrospectivo, se incluyó a 352 sujetos sometidos a una colonoscopia en nuestro centro, de los cuales 247 no mostraron ninguna alteración evidente (grupo control), mientras que 105 recibieron un diagnóstico de uno o múltiples pólipos (grupo de pacientes). Se compararon las moléculas del perfil lipídico sérico y los cocientes lipoproteicos de los dos grupos.

Resultados

El grupo de pacientes mostró niveles significativamente mayores de colesterol total (CT) y apolipoproteína B (ApoB) que el grupo de control (p<0,05). Entre los hombres, el grupo de pacientes mostró niveles de ApoB y una relación ApoB/ApoA1 superiores a los del grupo de control (p<0,05). Así mismo, los niveles de triglicéridos (TG) y la relación TG/C-HDL (colesterol de lipoproteínas de alta densidad) fueron significativamente más elevados en el grupo de pólipos múltiples que en el de un solo pólipo (p<0,05). Además, los niveles de C-HDL y la relación C-HDL/ApoA1 fueron más altos en el grupo con pólipos adenomatosos que en el de no adenomatosos (p<0,05). El análisis de regresión logística múltiple identificó al CT, TG, LDL-C y a los cocientes CT/C-HDL, TG/C-HDL y C-LDL/C-HDL como factores de riesgo para el desarrollo de pólipos colorrectales (p<0,05). Los análisis de la curva ROC revelaron una asociación entre el CT, la ApoB, y la relación ApoB/ApoA1 y los pólipos colorrectales. Por otro lado, no se observaron diferencias estadísticamente significativas en el IMC entre los dos grupos (p>0,05).

Conclusiones

La incidencia y evolución de los pólipos colorrectales están relacionados con las moléculas del perfil lipídico en suero y los cocientes lipoproteicos de las mismas. La dislipidemia podría incrementar el riesgo de desarrollar pólipos colorrectales, pudiendo derivar posteriormente en el desarrollo de cáncer colorrectal (CRC).

Association between blood lipid levels and the risk of liver cancer: a systematic review and meta-analysis

PURPOSE

The association between blood lipid levels and the risk of developing liver cancer remains a subject of ongoing debate. To elucidate this association, we conducted a meta-analysis by systematically incorporating data from all relevant prospective cohort studies.

METHODS

We conducted a systematic search of the PubMed, Embase, Web of Science, and Cochrane Library databases covering studies published from database inception through July 2023. This study included prospective cohort studies related to lipid profiles (e.g., total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) levels) that reported hazard ratios (HRs) or relative risks (RRs) with corresponding 95% confidence intervals (95% CIs) to investigate their association with the risk of liver cancer. During the analysis process, we used fixed-effects or random-effects models based on the level of heterogeneity among the studies and obtained pooled risk ratios using these models. To ensure the robustness and reliability of the study findings, we also conducted sensitivity analyses and publication bias analyses.

RESULTS

After conducting a systematic search, 12 studies were identified from a total of 11,904 articles and were included in the meta-analysis. These studies included a combined population of 10,765,221 participants, among whom 31,055 cases of liver cancer were reported. The analysis revealed that the pooled HR for the serum TC concentration (highest versus lowest) was 0.45 (95% CI = 0.35-0.58, I2 = 78%). For TGs, the HR was 0.67 (95% CI = 0.46-0.96, I2 = 86%), while for HDL-C, the HR was 0.72 (95% CI = 0.58-0.90, I2 = 65%). The HR for LDL-C was 0.51 (95% CI = 0.23-1.13, I2 = 93%).

CONCLUSION

The findings of this study indicate that serum TC, TG, and HDL-C levels are negatively associated with liver cancer risk, suggesting that higher concentrations of these lipids are associated with a reduced risk of liver cancer. However, no significant association has been found between LDL-C levels and liver cancer risk.

The Relationship Between Serum Lipids and the Formation of Colorectal Polyps

BACKGROUND AND AIMS

Obesity, metabolic syndrome, and hyperlipidemia are known as risk factors for colorectal tumors. Colorectal polyps are accepted as potential precursors of colorectal cancer (CRC). This study was designed to clarify the association between the levels of serum lipids and the presence of colorectal polyps.

METHODS

This study was conducted at Basaksehir Cam and Sakura City Hospital, Gastroenterological Surgery Clinic, Istanbul, Turkey. We retrospectively analyzed patients who underwent colonoscopy with serum lipid profile within one month for a one-year period. Groups were analyzed in terms of the correlation between hyperlipidemia and the formation of polyps. The study group was also evaluated in terms of the polyp type, localization, and number.

RESULTS

Among 453 patients, females were 248 and males were 211, with a mean age of 56.7. The study and control groups involved 259 and 194 patients, respectively. The age and serum levels of low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), and triglyceride (TG) were found to be statistically significant in terms of polyp presence and number (p < 0.05).

CONCLUSION

Colorectal polyps are well-known precursors of CRC. We found that the combination of elevated serum levels of low-density lipoprotein cholesterol, total cholesterol, and triglycerides may be a risk predictor for the presence of colorectal polyps, which can be advantageous in cancer screening.

The Association of Metabolic Risk Factors with Advanced Adenomas in Hispanic Patients

BACKGROUND

Obesity and metabolic syndrome (MetS) have been implicated as rising risk factors for the development of colorectal cancers. A rapid increase in the prevalence of obesity and severe obesity among Hispanic patients in the United States may present substantially increased risk for advanced colorectal neoplasia in this population. Currently, there is very little research in this area.

AIMS

We sought to identify metabolic risk factors for advanced adenomas (AA) in Hispanic Americans.

METHODS

We retrospectively reviewed data from the Los Angeles General (LAG) Medical Center of asymptomatic Hispanic patients above 45 years of age who underwent their first colonoscopies following a positive screening FBT. Patient demographics, metabolic characteristics, as well as colon polyp size and histology were recorded. Polyps were classified as adenomas or AA (including both high-risk adenomas and high-risk serrated polyps). Relative risk for AA was assessed by multivariate logistical regression analyses.

RESULTS

Of the 672 patients in our study, 41.4% were male, 67% had adenomas, and 16% had AA. The mean BMI was 31.2 kg/m2. The mean HDL-C was 49.5 mg/dL (1.28 mmol/L) and the mean triglyceride level was 151 mg/dL. 44.6% had diabetes and 64.1% had hypertension. When comparing patients with AA to patients with no adenoma, male sex, BMI > 34.9 kg/m2, and elevated fasting triglyceride levels were associated with an increased risk of AA. FIB-4 ≥1.45 was also associated with an increased risk of AA in males. There was no significant difference in the risk of AA with diabetes, hypertension, FIB-4 score, LDL-C level, and HDL-C level.

CONCLUSIONS

Hispanic patients with a positive FBT were observed to have a high incidence of AA. Class II obesity (BMI ≥ 35 kg/m2), elevated triglyceride levels were identified as risk factors among males in our study. Early interventions to address these modifiable risk factors in at-risk populations, such as multi-disciplinary weight management programs for the treatment of obesity and related co-morbidities, could potentially lead to risk reduction and CRC prevention.

Whole-transcriptome defines novel glucose metabolic subtypes in colorectal cancer

Colorectal cancer (CRC) is the most prevalent malignancy of the digestive system. Glucose metabolism plays a crucial role in CRC development. However, the heterogeneity of glucose metabolic patterns in CRC is not well characterized. Here, we classified CRC into specific glucose metabolic subtypes and identified the key regulators. 2228 carbohydrate metabolism-related genes were screened out from the GeneCards database, 202 of them were identified as prognosis genes in the TCGA database. Based on the expression patterns of the 202 genes, three metabolic subtypes were obtained by the non-negative matrix factorization clustering method. The C1 subtype had the worst survival outcome and was characterized with higher immune cell infiltration and more activation in extracellular matrix pathways than the other two subtypes. The C2 subtype was the most prevalent in CRC and was characterized by low immune cell infiltration. The C3 subtype had the smallest number of individuals and had a better prognosis, with higher levels of NRF2 and TP53 pathway expression. Secreted frizzled-related protein 2 (SFRP2) and thrombospondin-2 (THBS2) were confirmed as biomarkers for the C1 subtype. Their expression levels were elevated in high glucose condition, while their knockdown inhibited migration and invasion of HCT 116 cells. The analysis of therapeutic potential found that the C1 subtype was more sensitive to immune and PI3K-Akt pathway inhibitors than the other subtypes. To sum up, this study revealed a novel glucose-related CRC subtype, characterized by SFRP2 and THBS2, with poor prognosis but possible therapeutic benefits from immune and targeted therapies.

Identification of taxonomic changes in the fecal bacteriome associated with colorectal polyps and cancer: potential biomarkers for early diagnosis

Colorectal cancer (CRC) commonly arises in individuals with premalignant colon lesions known as polyps, with both conditions being influenced by gut microbiota. Host-related factors and inherent characteristics of polyps and tumors may contribute to microbiome variability, potentially acting as confounding factors in the discovery of taxonomic biomarkers for both conditions. In this study we employed shotgun metagenomics to analyze the taxonomic diversity of bacteria present in fecal samples of 90 clinical subjects (comprising 30 CRC patients, 30 with polyps and 30 controls). Our findings revealed a decrease in taxonomic richness among individuals with polyps and CRC, with significant dissimilarities observed among the study groups. We identified significant alterations in the abundance of specific taxa associated with polyps (Streptococcaceae, Lachnoclostridium, and Ralstonia) and CRC (Lactobacillales, Clostridiaceae, Desulfovibrio, SFB, Ruminococcus, and Faecalibacterium). Clostridiaceae exhibited significantly lower abundance in the early stages of CRC. Additionally, our study revealed a positive co-occurrence among underrepresented genera in CRC, while demonstrating a negative co-occurrence between Faecalibacterium and Desulfovibrio, suggesting potential antagonistic relationships. Moreover, we observed variations in taxonomic richness and/or abundance within the polyp and CRC bacteriome linked to polyp size, tumor stage, dyslipidemia, diabetes with metformin use, sex, age, and family history of CRC. These findings provide potential new biomarkers to enhance early CRC diagnosis while also demonstrating how intrinsic host factors contribute to establishing a heterogeneous microbiome in patients with CRC and polyps.

Association of clinical characteristics and recurrence of conventional colorectal adenomas with patient age: a single-center study

OBJECTIVES

We performed a clinical study comparing early-onset and late-onset conventional colorectal adenomas (CCRAs) since little is known about the differences in their characteristics.

METHODS

Pearson's chi-square test and the Kruskal‒Wallis test were used to compare basic information. MCAR tests and multiple imputation were performed to complete missing values. Multivariate logistic analysis and propensity score matching were used to identify the risk factors for recurrence.

RESULTS

We included 2793 patients (688 with early-onset CCRAs and 2105 with late-onset CCRAs) from January 2017 to December 2021. Patients with early-onset CCRAs had higher levels of Hb, ALB, and triglycerides but lower HDL levels and N/L ratios. Moreover, we found that more early-onset CCRAs were in the left colon than late-onset CCRAs, and the size of early-onset CCRAs was larger. Early-onset CCRAs tended to lack pedicles compared to late-onset CCRAs. Additionally, the ratio of EMR and APC in early-onset CCRAs was higher than that in late-onset CCRAs, and the ratio of ESD and surgery for late-onset CCRAs was higher. We found that age ≥ 50 years, abnormal vessels, drinking alcohol, and DB and ALB levels may be risk factors for recurrence, while the LDL level may be a protective factor. Finally, analysis of cumulative recurrence rates after PSM showed that patients with late-onset CCRAs exhibited higher recurrence rates (P < 0.05).

CONCLUSION

Compared with late-onset CCRAs, early-onset CCRAs were associated with higher triglyceride levels, lower HDL levels, and larger tumor volumes. Age ≥ 50 years, abnormal vessels, alcohol consumption, and DB and ALB levels were independent risk factors for recurrence of CCRAs.

High-density lipoprotein cholesterol and carcinogenesis

High-density lipoprotein cholesterol (HDLC) has been recognized to be associated with atherosclerosis. In the past few years many studies have found that HDLC is also related to tumor development and progression. Despite some opposing views, a large number of studies support a negative association between HDLC and tumor incidence. Measuring serum HDLC concentrations may facilitate assessment of the prognosis of cancer patients and provide a biomarker for tumors. However, there is a lack of molecular mechanism studies on the link between HDLC and tumors. In this review we discuss the impact of HDLC on the incidence and prognosis of cancer in different systems, as well as prospects for the prediction and treatment of cancer in the future.

The Relationship Between Colorectal Polyps and Serum Lipid Levels: A Systematic Review and Meta-analysis

Colorectal polyp has been considered as the precancerous lesion of colorectal cancer, to which serum lipid levels are closely related. At present, there is no consensus on the relationship between colorectal polyps and serum lipid levels. We performed a meta-analysis to explore the effects of lipid levels on colorectal polyps. Relevant articles published from 2000 to 2020 were searched in PubMed, Web of Science, EMBASE, and Cochrane Library databases. The mean value and SD of serum lipid indexes and body mass index in colorectal polyps groups and control groups were extracted from the included articles. Combined weighted mean differences (WMDs) and 95% confidence intervals (CIs) were calculated to assess the effect size of serum lipid levels on colorectal polyps. The publication bias of the included studies were assessed based on the Egger test. Thirty-seven articles containing 19,464 cases and 63,979 controls were included. There were no significant publication bias. The levels of high-density lipoprotein cholesterol in the cases were lower than those in the controls (WMD: -2.589 mg/dL, 95% CI: -3.273, -1.906). While the levels of triglyceride (WMD: 16.933 mg/dL, 95% CI: 13.131, 20.736), total cholesterol (WMD: 5.561 mg/dL, 95% CI: 3.477, 7.645), low-density lipoprotein cholesterol (WMD: 3.109 mg/dL, 95% CI: 0.859, 5.359) and body mass index (WMD: 0.747 mg/dL, 95% CI: 0.588, 0.906) were higher in the cases. Colorectal polyps were associated with serum lipid levels and obesity. Hyperlipidemia and obesity may be the risk factors for colorectal polyps.

Factors Associated with Colorectal Polyps in Middle-Aged and Elderly Populations

Colorectal polyps are the precursor lesions of most colorectal cancers. This study aimed to evaluate associations between bone mineral density (BMD), metabolic syndrome (MetS), and gastrointestinal diseases with colorectal polyps in middle-aged and elderly populations. A retrospective cross-sectional study was performed using data from the health examination database of a tertiary medical center in southern Taiwan in 2015. Subjects aged 50 years and older who had been assessed for metabolic factors and had undergone colonoscopy, upper gastrointestinal endoscopy, and dual energy X-ray absorptiometry scan (DEXA) were included. Factors associated with colorectal polyps were evaluated using univariate and multivariate logistic regression. In total, 1515 subjects were included, with mean age 60.1 years. Among them, 710 (46.9%) had colorectal polyps. Multivariate logistic regression analysis showed that high fasting glucose (OR = 1.08, p = 0.001), high triglycerides (OR = 1.02, p = 0.008), high total cholesterol (OR = 1.004, p = 0.009), reflux esophagitis (OR = 1.44, p = 0.002), duodenal polyps (OR = 1.75, p = 0.026), gastric ulcer (OR = 1.38, p = 0.024), duodenal ulcers (OR = 1.45, p = 0.028), osteopenia (OR = 1.48, p = 0.001), and MetS (OR = 1.46, p < 0.001) were independently associated with colorectal polyps. In conclusion, hyperglycemia, hypercholesterolemia, hypertriglyceridemia, MetS, duodenal polyps, gastric and duodenal ulcers, reflux esophagitis, and low BMD are independent risk factors associated with colorectal polyps in the middle-aged and elderly Taiwanese population.

Antitumor activity and molecular mechanism of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a member of the proprotein convertase family of proteins that activate other proteins in cells. Functionally, PCSK9 binds to the receptor of low-density lipoprotein particles (LDL) to regulate cholesterol metabolism and lipoprotein homeostasis in human body. PCSK9 inhibition is a novel pharmacological strategy to control hypercholesterolemia and cardiovascular diseases. Recently accumulating evidence realizes that PCSK9 possesses other roles in cells, such as regulation of tissue inflammatory response, intratumoral immune cell infiltration, and tumor progression. This review discussed the advancement of PCSK9 research on its role and underlying mechanisms in tumor development and progression. For example, PCSK9 inhibition could attenuate progression of breast cancer, glioma, colon tumor, hepatocellular cancer, prostate cancer, and lung adenocarcinoma and promote apoptosis of glioma, prostate cancer, and hepatocellular cancer cells. PCSK9 deficiency could reduce liver metastasis of B16F1 melanoma cells by lowering the circulating cholesterol levels. PCSK9 gene knockdown substantially attenuated mouse tumor growth in vivo by activation of cytotoxic T cells, although PCSK9 knockdown had no effect on morphology and growth rate of different mouse cancer cell lines in vitro. PCSK9 inhibition thus can be used to control human cancers. Future preclinical and clinical studies are warranted to define anti-tumor activity of PCSK9 inhibition.

Expression of Autophagic and Inflammatory Markers in Normal Mucosa of Individuals with Colorectal Adenomas: A Cross Sectional Study among Italian Outpatients Undergoing Colonoscopy

Colorectal cancer (CRC) ranks among the three most common cancers in terms of both cancer incidence and cancer-related deaths in Western industrialized countries. Lifetime risk of colorectal cancer may reach 6% of the population living in developed countries. In the current era of personalized medicine, CRC is no longer considered as a single entity. In more recent years many studies have described the distinct differences in epidemiology, pathogenesis, genetic and epigenetic alterations, molecular pathways and outcome depending on the anatomical site. The aim of our study is to assess in a multidimensional model the association between metabolic status and inflammatory and autophagic changes in the normal colorectal mucosa classified as right-sided, left-sided and rectum, and the presence of adenomas. One hundred and sixteen patients undergoing colonoscopy were recruited and underwent a complete serum lipid profile, immunofluorescence analysis of colonic biopsies for MAPLC3 and myeloperoxidase expression, matched with clinical and anthropometric characteristics. Presence of adenomas correlated with cholesterol (total and LDL) levels, IL-6 levels, and MAPLC3 tissue expression, especially in the right colon. In conclusion, serum IL-6 amount and autophagic markers could be good predictors of the presence of colorectal adenomas.

Long-Term Statin Use, Total Cholesterol Level, and Risk of Colorectal Cancer: A Prospective Cohort Study

INTRODUCTION

Statin use has been examined as a potential chemopreventive strategy against colorectal cancer (CRC). Previous studies have not been able to investigate this topic with adequate follow-up time or disentangle the effects of statin use and total cholesterol level. We investigated prospectively this topic.

METHODS

Eligible participants (100,300 women and 47,991 men) in the Nurses' Health Study and Health Professionals Follow-Up Study were followed for up to 24 years. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals.

RESULTS

We documented 2,924 incident CRC cases during follow-up. In fully adjusted analyses, longer duration of statin use was associated with higher risk of colon cancer (hazard ratios, the 95% confidence interval was 1.09, 0.95-1.25 for 1-5 years; 1.16, 0.99-1.36 for 6-10 years; 1.08, 0.81-1.44 for 11-15 years; 1.85, 1.30-2.61 for >15 years; vs never users, P = 0.004 for trend) rather than rectal cancer. The risk elevation was driven by proximal colon cancer (1.16, 0.98-1.38 for 1-5 years; 1.19, 0.98-1.45 for 6-10 years; 1.25, 0.89-1.74 for 11-15 years; 2.17, 1.46-3.24 for >15 years; vs never users, P = 0.001 for trend) rather than distal colon cancer. The results remained robust in analyses among participants with hypercholesterolemia or who never received screening. Total cholesterol level was not associated with CRC risk.

DISCUSSION

This study does not support benefit of statin use in CRC chemoprevention or any association between total cholesterol level and CRC risk. On the contrary, long-term statin use may be associated with increased colon cancer risk (driven by proximal colon cancer).

Blood lipids and risk of colon or rectal cancer: a Mendelian randomization study

PURPOSE

Recent Mendelian randomization (MR) studies derived inconsistent results of blood lipids' effect on colorectal cancer, and whether the blood lipids' effect on colon and rectal cancer is different is still unknown. Here, we sought to answer these questions.

METHODS

Primarily, we employed univariable MR to explore the blood lipids' effect on colon and rectal cancer, including high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol and triglycerides. Then, multivariable MR was also employed to reassess each blood lipid's effect on the two cancers with adjustment of the other lipids. Reverse MR analysis was adopted to determine whether colon or rectal cancer could affect the levels of blood lipids. The Cochrane's Q value was used to evaluate the heterogeneity, and MR-PRESSO was used to appraise the pleiotropy.

RESULTS

Generally, we did not find any significant result between blood lipids and the colon/rectal cancer after Bonferroni correction in the univariable MR analysis. The multivariable MR analysis also obtained the same results. However, it should be noted that higher total cholesterol level might increase the risk of colon cancer (OR = 1.15 [1.01, 1.31], IVW p value = 0.029) but not rectal cancer (OR = 1.02 [0.85, 1.21], IVW p value = 0.853). Such causal relationship turned insignificant in the multivariable MR. The reverse MR analysis suggested that either colon or rectal cancer could increase the levels of blood lipids.

CONCLUSION

We found no association between blood lipids and risk of colon or rectal cancer, except for a positive association between total cholesterol and colon cancer risk.

PCSK9 and cancer: Rethinking the link

BACKGROUND

Cancer is emerging as a major problem globally, as it accounts for the second cause of death despite medical advances. According to epidemiological and basic studies, cholesterol is involved in cancer progression and there are abnormalities in cholesterol metabolism of cancer cells including prostate, breast, and colorectal carcinomas. However, the importance of cholesterol in carcinogenesis and thereby the role of cholesterol homeostasis as a therapeutic target is still a debated area in cancer therapy. Proprotein convertase subtilisin/kexin type-9 (PCSK9), a serine protease, modulates cholesterol metabolism by attachment to the LDL receptor (LDLR) and reducing its recycling by targeting the receptor for lysosomal destruction. Published research has shown that PCSK9 is also involved in degradation of other LDLR family members namely very-low-density-lipoprotein receptor (VLDLR), lipoprotein receptor-related protein 1 (LRP-1), and apolipoprotein E receptor 2 (ApoER2). As a result, this protein represents an interesting therapeutic target for the treatment of hypercholesterolemia. Interestingly, clinical trials on PCSK9-specific monoclonal antibodies have reported promising results with high efficacy in lowering LDL-C and in turn reducing cardiovascular complications. It is important to note that PCSK9 mediates several other pathways apart from its role in lipid homeostasis, including antiviral activity, hepatic regeneration, neuronal apoptosis, and modulation of various signaling pathways. Furthermore, recent literature has illustrated that PCSK9 is closely associated with incidence and progression of several cancers. In a number of studies, PCSK9 siRNA was shown to effectively suppress the proliferation and invasion of the several studied tumor cells. Hence, a novel application of PCSK9 inhibitors/silencers in cancer/metastasis could be considered. However, due to poor data on effectiveness and safety of PCSK9 inhibitors in cancer, the impact of PCSK9 inhibition in these pathological conditions is still unknown.

SEARCH METHODS

A vast literature search was conducted to find intended studies from 1956 up to 2020, and inclusion criteria were original peer-reviewed publications.

PURPOSE OF REVIEW

To date, PCSK9 has been scantly investigated in cancer. The question that needs to be discussed is "How does PCSK9 act in cancer pathophysiology and what are the risks or benefits associated to its inhibition?". We reviewed the available publications highlighting the contribution of this proprotein convertase in pathways related to cancer, with focus on the potential implications of its long-term pharmacological inhibition in cancer therapy.

Targeting HDL in tumor microenvironment: New hope for cancer therapy

Epidemiological studies have shown that plasma HDL-C levels are closely related to the risk of prostate cancer, breast cancer, and other malignancies. As one of the key carriers of cholesterol regulation, high-density lipoprotein (HDL) plays an important role in tumorigenesis and cancer development through anti-inflammation, antioxidation, immune-modulation, and mediating cholesterol transportation in cancer cells and noncancer cells. In addition, the occurrence and progression of cancer are closely related to the alteration of the tumor microenvironment (TME). Cancer cells synthesize and secrete a variety of cytokines and other factors to promote the reprogramming of surrounding cells and shape the microenvironment suitable for cancer survival. By analyzing the effect of HDL on the infiltrating immune cells in the TME, as well as the relationship between HDL and tumor-associated angiogenesis, it is suggested that a moderate increase in the level of HDL in vivo with consequent improvement of the function of HDL in the TME and induction of intracellular cholesterol efflux may be a promising strategy for cancer therapy.

Pleiotropic Effects of PCSK-9 Inhibitors

Proprotein convertase subtilisin/kexin type 9 (PCSK-9) inhibitors are a group of drugs whose main mechanism of action is binding to the PCSK-9 molecule, which reduces the degradation of the low-density lipoprotein receptor (LDL-R) and, hence, increases the uptake of low-density lipoprotein cholesterol (LDLc) from the bloodstream as well as reducing its concentration. The effectiveness of three monoclonal antibodies, namely, alirocumab (human IgG1/κ monoclonal antibody, genetically engineered in Chinese hamster ovary cells), evolocumab (the first fully human monoclonal antibody), and bococizumab (humanized mouse antibody), in inhibiting the action of PCSK-9 and reducing LDLc levels has been confirmed. The first two, after clinical trials, were approved by the Food and Drug Administration (FDA) and are used primarily in the treatment of autosomal familial hypercholesterolemia and in cases of statin intolerance. They are currently used both as monotherapy and in combination with statins and ezetimibe to intensify therapy and achieve therapeutic goals following the American Heart Association (AHA) and European Society of Cardiology (ESC) guidelines. However, the lipid-lowering effect is not the only effect of action described by researchers that PCSK-9 inhibitors have. This paper is a review of the literature describing the pleiotropic effects of PCSK-9 inhibitors, which belong to a group of drugs that are being increasingly used, especially when standard lipid-lowering therapy fails. The article focuses on activities other than lipid-lowering, such as the anti-atherosclerotic effect and stabilization of atherosclerotic plaque, the anti-aggregation effect, the anticoagulant effect, the antineoplastic effect, and the ability to influence the course of bacterial infections. In this publication, we try to systematically review the current scientific data, both from our own scientific work and knowledge from international publications.

Predicting the effect of statins on cancer risk using genetic variants from a Mendelian randomization study in the UK Biobank

Laboratory studies have suggested oncogenic roles of lipids, as well as anticarcinogenic effects of statins. Here we assess the potential effect of statin therapy on cancer risk using evidence from human genetics. We obtained associations of lipid-related genetic variants with the risk of overall and 22 site-specific cancers for 367,703 individuals in the UK Biobank. In total, 75,037 individuals had a cancer event. Variants in the HMGCR gene region, which represent proxies for statin treatment, were associated with overall cancer risk (odds ratio [OR] per one standard deviation decrease in low-density lipoprotein [LDL] cholesterol 0.76, 95% confidence interval [CI] 0.65-0.88, p=0.0003) but variants in gene regions representing alternative lipid-lowering treatment targets (PCSK9, LDLR, NPC1L1, APOC3, LPL) were not. Genetically predicted LDL-cholesterol was not associated with overall cancer risk (OR per standard deviation increase 1.01, 95% CI 0.98-1.05, p=0.50). Our results predict that statins reduce cancer risk but other lipid-lowering treatments do not. This suggests that statins reduce cancer risk through a cholesterol independent pathway.

Mendelian randomization analysis rules out disylipidaemia as colorectal cancer cause

Dyslipidemia and statin use have been associated with colorectal cancer (CRC), but prospective studies have shown mixed results. We aimed to determine whether dyslipidemia is causally linked to CRC risk using a Mendelian randomization approach and to explore the association of statins with CRC. A case-control study was performed including 1336 CRC cases and 2744 controls (MCC-Spain). Subjects were administered an epidemiological questionnaire and were genotyped with an array which included polymorphisms associated with blood lipids levels, selected to avoid pleiotropy. Four genetic lipid scores specific for triglycerides (TG), high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol (LDL), or total cholesterol (TC) were created as the count of risk alleles. The genetic lipid scores were not associated with CRC. The ORs per 10 risk alleles, were for TG 0.91 (95%CI: 0.72-1.16, p = 0.44), for HDL 1.14 (95%CI: 0.95-1.37, p = 0.16), for LDL 0.97 (95%CI: 0.81-1.16, p = 0.73), and for TC 0.98 (95%CI: 0.84-1.17, p = 0.88). The LDL and TC genetic risk scores were associated with statin use, but not the HDL or TG. Statin use, overall, was a non-significant protective factor for CRC (OR 0.84; 95%CI: 0.70-1.01, p = 0.060), but lipophilic statins were associated with a CRC risk reduction (OR 0.78; 95%CI 0.66-0.96, p = 0.018). Using the Mendelian randomization approach, our study does not support the hypothesis that lipid levels are associated with the risk of CRC. This study does not rule out, however, a possible protective effect of statins in CRC by a mechanism unrelated to lipid levels.

Potential anti-tumor effect of a nanoliposomal antiPCSK9 vaccine in mice bearing colorectal cancer

INTRODUCTION

Inhibition of proprotein convertase subtilisin/kexin 9 (PCSK9) is an effective therapeutic tool for lowering low-density lipoprotein cholesterol (LDL-C). There is no available evidence on the efficacy and safety of PCSK9 inhibitors in non-cardiovascular diseases, particularly cancer. The present study aimed to evaluate the effect of PCSK9 inhibition on cancer endpoints in mice bearing colon carcinoma, using a nanoliposomal antiPCSK9 vaccine.

MATERIAL AND METHODS

The prepared nanoliposomal antiPCSK9 vaccine was subcutaneously inoculated in BALB/c mice four times with a biweekly interval. Two weeks after the last booster, the vaccinated and unvaccinated mice were subcutaneously inoculated with CT26 colon cancer cells into the right flank. After the tumor mass became palpable, the mice were randomly divided into three groups: (1) PBS (untreated control), (2) vaccine group, and (3) pegylated liposomal doxorubicin (PLD; positive control) group. Body weight, tumor size and survival of mice were monitored for 50 days.

RESULTS

The nanoliposomal antiPCSK9 vaccine could efficiently provoke specific antibodies against PCSK9 in BALB/c mice and thereby reduced the plasma level and function of PCSK9. Tumor volume was 77% and 87.7% lower (p < 0.0001) in the vaccinated mice when compared with Doxil (liposomal doxorubicin) and control mice, respectively. Tumor size analysis showed that time to reach the endpoint of the vaccine group (47 ±11 days) was slightly but not significantly higher than PLD (46 ±2.6 days) and the control (43 ±12 days) groups. The tumor growth rates in the vaccine and PLD groups were reduced by 9.3% and 7.3, respectively, when compared with the control group. The vaccinated mice survived slightly but not significantly longer than PLD and the control mice. The median survival of the vaccine, PLD and control groups were 51, 45, and 41 days, respectively. The vaccinated mice's life was prolonged by 24.4% as compared with the control mice, while it was increased by 9.8% in the PLD group.

CONCLUSIONS

Our results revealed that PCSK9 inhibition not only exerted no harmful effects but also could moderately inhibit tumor growth, and improve lifespan and survival in mice bearing colon cancer.

Changes in lipids composition and metabolism in colorectal cancer: a review

Altered metabolism of lipids is currently considered a hallmark characteristic of many malignancies, including colorectal cancer (CRC). Lipids are a large group of metabolites that differ in terms of their fatty acid composition. This review summarizes recent evidence, documenting many alterations in the content and composition of fatty acids, polar lipids, oxylipins and triacylglycerols in CRC patients' sera, tumor tissues and adipose tissue. Some of altered lipid molecules may be potential biomarkers of CRC risk, development and progression. Owing to a significant role of many lipids in cancer cell metabolism, some of lipid metabolism pathways may also constitute specific targets for anti-CRC therapy.

Changes in lecithin: cholesterol acyltransferase, cholesteryl ester transfer protein and paraoxonase-1 activities in patients with colorectal cancer

BACKGROUND

Previous studies revealed decreased level of high-density lipoprotein cholesterol (HDLC) as important factor for development of colorectal cancer (CRC). Quantity and structure of HDL particles depend on activities of lipid transfer proteins lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP), but this topic is largely unexplored in CRC. The main objective of this study was to investigate activities of LCAT and CETP in patients with CRC. Additionally, we analyzed activity of paraoxonase-1 (PON-1), as a main carrier of HDL-antioxidant function.

MATERIALS AND METHODS

Ninety-nine CRC patients and 101 healthy individuals were included. LCAT and CETP activities were assessed by measuring rates of formation and transfer of cholesteryl esters. PON-1 paraoxonase and arylesterase activities were measured.

RESULTS

Lower levels of HDL-C (p < .001) were observed in cohort of patients, alongside with decreased LCAT (p < .050) and increased CETP activity (p < .050). Both PON-1 activities were diminished in CRC (p < .050 and p < .001 respectively). Univariate logistic regression singled out HDL-C level (OR = 0.218, p < .001), CETP activity (OR = 1.010, p < .01) and mass (OR = 0.994, p < .001) as possible markers of elevated CRC risk. CETP mass maintained its predictive significance when adjusted for traditional risk factors and level of oxidative stress (OR = 0.993, p < .001; OR = 0.982, p < .050, respectively).

CONCLUSION

Our results demonstrated increased CETP and decreased LCAT and PON-1 activities in CRC patients. In preliminary analysis CETP mass was identified as potential significant predictor of CRC development, suggesting that alterations in HDL-C levels, alongside with changes in HDL structure might have a role in carcinogenesis.

Gallbladder stones and gallbladder polyps associated with increased risk of colorectal adenoma in men

BACKGROUND AND AIMS

Most cases of colorectal cancer develop via an adenoma to carcinoma sequence. Gallbladder polyps share some risk factors with colorectal polyps. Little is known about the relationship between gallbladder diseases and different status of colorectal polyps by gender. This study was to investigate the association of gallbladder stones and polyps with colorectal adenomas by gender in a Taiwanese population.

METHODS

A total of 7066 eligible subjects who underwent a total colonoscopy as a part of health check-up between January 2001 and August 2009 were recruited. Colonoscopic findings were classified into polyp-free, non-neoplastic polyps and colorectal adenomas. Gallbladder stones and gallbladder polyps were diagnosed based on ultrasonographic findings.

RESULTS

There was a significant difference in the status of colon polyps between subjects with and without gallbladder polyps. However, the status of colon polyps was not significantly different between subjects with or without gallbladder stones. After adjusting obesity, fasting plasma glucose, and other variables, there was a positive relationship between gallbladder polyps and colorectal adenomas (odds ratio [OR]: 1.396, 95% confidence interval [CI]: 1.115-1.747) but not non-neoplastic polyps in all subjects. In men, gallbladder polyps (OR: 1.560, 95% CI: 1.204-2.019) and gallbladder stones (OR: 1.465, 95% CI 1.081-1.984) were positively associated with colorectal adenomas. In women, neither gallbladder polyps nor gallbladder stones were significantly related to colon polyps.

CONCLUSIONS

Both gallbladder polyps and gallbladder stones were associated with an increased risk of colorectal adenomas in men but not in women. Gender difference was significant for the association between gallbladder lesions and colorectal polyps.

Epidemiology and risk factors of colorectal polyps

The lifetime risk of colorectal cancer (CRC) in the Western world is around 5%. CRC commonly develops from precursor lesions termed polyps, classified as adenomatous or serrated polyps according to growth pattern. Despite the well-known connection between polyps and cancer, most polyps will never develop into CRC. For those that do, the time until CRC development is generally thought of as >10 years. This gives opportunity for interventional strategies to prevent transformation into cancer. This article aims to provide an overview of the epidemiology of and risk factors for colorectal polyps in the average risk population, and will encompass the effect of age, gender, ethnicity, smoking, obesity, alcohol, physical activity, NSAIDs and dietary factors on colorectal polyps.