Germline genetic variants associated with prostate cancer and potential relevance to clinical practice

Recent advances and future perspectives in the therapeutics of prostate cancer

Prostate cancer (PC) is one of the most common cancers in males and the fifth leading reason of death. Age, ethnicity, family history, and genetic defects are major factors that determine the aggressiveness and lethality of PC. The African population is at the highest risk of developing high-grade PC. It can be challenging to distinguish between low-risk and high-risk patients due to the slow progression of PC. Prostate-specific antigen (PSA) is a revolutionary discovery for the identification of PC. However, it has led to an increase in over diagnosis and over treatment of PC in the past few decades. Even if modifications are made to the standard PSA testing, the specificity has not been found to be significant. Our understanding of PC genetics and proteomics has improved due to advances in different fields. New serum, urine, and tissue biomarkers, such as PC antigen 3 (PCA3), have led to various new diagnostic tests, such as the prostate health index, 4K score, and PCA3. These tests significantly reduce the number of unnecessary and repeat biopsies performed. Chemotherapy, radiotherapy, and prostatectomy are standard treatment options. However, newer novel hormone therapy drugs with a better response have been identified. Androgen deprivation and hormonal therapy are evolving as new and better options for managing hormone-sensitive and castration-resistant PC. This review aimed to highlight and discuss epidemiology, various risk factors, and developments in PC diagnosis and treatment regimens.

Role of GARP Vesicle Tethering Complex in Golgi Physiology

The Golgi associated retrograde protein complex (GARP) is an evolutionarily conserved component of Golgi membrane trafficking machinery that belongs to the Complexes Associated with Tethering Containing Helical Rods (CATCHR) family. Like other multisubunit tethering complexes such as COG, Dsl1, and Exocyst, the GARP is believed to function by tethering and promoting fusion of the endosome-derived small trafficking intermediate. However, even twenty years after its discovery, the exact structure and the functions of GARP are still an enigma. Recent studies revealed novel roles for GARP in Golgi physiology and identified human patients with mutations in GARP subunits. In this review, we summarized our knowledge of the structure of the GARP complex, its protein partners, GARP functions related to Golgi physiology, as well as cellular defects associated with the dysfunction of GARP subunits.

Genetic Factors Associated with Prostate Cancer Conversion from Active Surveillance to Treatment

Men diagnosed with low-risk prostate cancer (PC) are increasingly electing active surveillance (AS) as their initial management strategy. While this may reduce the side effects of treatment for prostate cancer, many men on AS eventually convert to active treatment. PC is one of the most heritable cancers, and genetic factors that predispose to aggressive tumors may help distinguish men who are more likely to discontinue AS. To investigate this, we undertook a multi-institutional genome-wide association study (GWAS) of 5,222 PC patients and 1,139 other patients from replication cohorts, all of whom initially elected AS and were followed over time for the potential outcome of conversion from AS to active treatment. In the GWAS we detected 18 variants associated with conversion, 15 of which were not previously associated with PC risk. With a transcriptome-wide association study (TWAS), we found two genes associated with conversion (MAST3, p = 6.9×10-7 and GAB2, p = 2.0×10-6). Moreover, increasing values of a previously validated 269-variant genetic risk score (GRS) for PC was positively associated with conversion (e.g., comparing the highest to the two middle deciles gave a hazard ratio [HR] = 1.13; 95% Confidence Interval [CI]= 0.94-1.36); whereas, decreasing values of a 36-variant GRS for prostate-specific antigen (PSA) levels were positively associated with conversion (e.g., comparing the lowest to the two middle deciles gave a HR = 1.25; 95% CI, 1.04-1.50). These results suggest that germline genetics may help inform and individualize the decision of AS-or the intensity of monitoring on AS-versus treatment for the initial management of patients with low-risk PC.

VPS53 Suppresses Malignant Properties in Colorectal Cancer by Inducing the Autophagy Signaling Pathway

Background

Many studies found that VPS53, one of the subunits of the golgi-associated retrograde protein (GARP) complexes, was aberrantly expressed in human diseases.

Aim

This study investigated the functions and molecular mechanisms of VPS53 in colorectal cancer (CRC).

Methods

Expression and correlation of Beclin 1 and VPS53 were analyzed by RT-qPCR and Pearson’s correlation in CRC tissues, and VPS53 expression was also determined in CRC cells. The changes of proliferation, migration, invasion, apoptosis, and autophagy of CRC cells were examined by a succession of functional experiments including CCK-8, flow cytometry, transwell assay, and electron microscopy. The levels of autophagy related proteins were evaluated by Western blotting analysis.

Results

RT-qPCR results found that VPS53 was downregulated in CRC tissues and cells, and Beclin 1 expression was also decreased in CRC tissues. There was a positive correlation between VPS53 and Beclin 1. Functional results showed that overexpression of VPS53 could suppress proliferation, migration, and invasion, and accelerate apoptosis and autophagy of CRC cells. Also, VPS53 could upregulate Beclin 1 and LC3BII, suggesting the inductive effect of VPS53 on CRC cell autophagy. Furthermore, it was found that the autophagy inhibitor (Inhb) could attenuate the inhibition of VPS53 on CRC progression.

Conclusion

VPS53 repressed CRC progression by regulating the autophagy signaling pathway, suggesting that VPS53 might be a promising therapeutic target for CRC.

Genetic variants in RNA-induced silencing complex genes and prostate cancer

PURPOSE

The purpose of this study is to evaluate the potential association between genetic variants in genes encoding the components of RNA-induced silencing complex and prostate cancer (PCa) risk. Genetic variants chosen for this study are rs3742330 in DICER1, rs4961280 in AGO2, rs784567 in TARBP2, rs7813 in GEMIN4 and rs197414 in GEMIN3.

METHODS

The study involved 355 PCa patients, 360 patients with benign prostatic hyperplasia and 318 healthy controls. For individuals diagnosed with PCa, clinicopathological characteristics including serum prostate-specific antigen level at diagnosis, Gleason score (GS) and clinical stage were determined. Genotyping was performed using high-resolution melting analysis, PCR-RFLP, TaqMan SNP Genotyping Assay and real-time PCR-based genotyping assay using specific probes. Allelic and genotypic associations were evaluated by unconditional linear and logistic regression methods.

RESULTS

The study provided no evidence of association between the analyzed genetic variants and PCa risk. Nevertheless, allele A of rs784567 was found to confer the reduced risk of higher serum PSA level at diagnosis (P = 0.046; Difference = -66.64, 95 % CI -131.93 to 1.35, for log-additive model). Furthermore, rs4961280, as well as rs3742330, were shown to be associated with GS. These variants, together with rs7813, were found to be associated with the lower clinical stage of PCa. Also, rs3742330 minor allele G was found to be associated with lower PCa aggressiveness (P = 0.036; OR 0.14, 95 % CI 0.023-1.22, for recessive model).

CONCLUSIONS

According to our data, rs3742330, rs4961280 and rs7813 qualify for potentially protective genetic variants against PCa progression. These variants were not shown to be associated with PCa risk.

Prevention and early detection of prostate cancer

Prostate cancer is a common malignancy in men and the worldwide burden of this disease is rising. Lifestyle modifications such as smoking cessation, exercise, and weight control offer opportunities to reduce the risk of developing prostate cancer. Early detection of prostate cancer by prostate-specific antigen (PSA) screening is controversial, but changes in the PSA threshold, frequency of screening, and the use of other biomarkers have the potential to minimise the overdiagnosis associated with PSA screening. Several new biomarkers for individuals with raised PSA concentrations or those diagnosed with prostate cancer are likely to identify individuals who can be spared aggressive treatment. Several pharmacological agents such as 5α-reductase inhibitors and aspirin could prevent development of prostate cancer. In this Review, we discuss the present evidence and research questions regarding prevention, early detection of prostate cancer, and management of men either at high risk of prostate cancer or diagnosed with low-grade prostate cancer.

A review of cancer risk prediction models with genetic variants

Cancer risk prediction models are important in identifying individuals at high risk of developing cancer, which could result in targeted screening and interventions to maximize the treatment benefit and minimize the burden of cancer. The cancer-associated genetic variants identified in genome-wide or candidate gene association studies have been shown to collectively enhance cancer risk prediction, improve our understanding of carcinogenesis, and possibly result in the development of targeted treatments for patients. In this article, we review the cancer risk prediction models that have been developed for popular cancers and assess their applicability, strengths, and weaknesses. We also discuss the factors to be considered for future development and improvement of models for cancer risk prediction.