Association of a novel genetic variant in RP11-650L12.2 with risk of colorectal cancer in Han Chinese population

Current Surveillance After Treatment is Not Sufficient for Patients With Rectal Cancer With Negative Baseline CEA

BACKGROUND

Serum CEA has been widely used to screen for potential recurrent disease after resection in rectal cancer. However, the influence of baseline CEA on the performance of CEA in recurrence surveillance needs to be investigated.

PATIENTS AND METHODS

This longitudinal cohort study included 484 patients with nonmetastatic rectal cancer from 18,013 patients in a prospectively enrolled institutional database program of colorectal disease. Baseline CEA levels were determined before treatment, and CEA-based follow-up tests and examinations were applied in the surveillance after treatment.

RESULTS

A total of 62.6% (62/99) overall, 53.5% (23/43) local, and 64.9% (50/77) distant recurrences were seen in patients who had similar CEA levels with their baseline statuses. The sensitivity of elevated CEA levels during surveillance for overall recurrence was significantly lower in patients with negative baseline CEA than in those with elevated baseline CEA levels (41.3% vs 69.4%; P =.007). Moreover, similar results were observed in the surveillance for local (50% vs 61.5%; P =.048) and distant (39.6% vs 72.4%; P =.005) recurrences between these 2 patient groups. However, CEA had comparable and excellent specificity during surveillance for recurrent disease in these groups. The addition of CA19-9 to the CEA assay significantly improved the sensitivity in recurrence surveillance for patients with negative baseline CEA (49.2% vs 41.3%; P =.037). Finally, we identified a subgroup of CEA-turn recurrences characterized by negative CEA at baseline, elevated CEA at recurrence, and worse survival outcomes after recurrence (hazard ratio, 1.88; 95% CI, 1.07-3.30; P =.026).

CONCLUSIONS

In patients with rectal cancer with negative baseline CEA, serum CEA had insufficient sensitivity in recurrence surveillance after treatment, and additional surveillance may improve oncologic outcomes. Baseline CEA should be considered before CEA-based surveillance can be applied in the follow-up trials.

Nine-long non-coding ribonucleic acid signature can improve the survival prediction of colorectal cancer

BACKGROUND

Investigating molecular biomarkers that accurately predict prognosis is of considerable clinical significance. Accumulating evidence suggests that long non-coding ribonucleic acids (lncRNAs) are frequently aberrantly expressed in colorectal cancer (CRC).

AIM

To elucidate the prognostic function of multiple lncRNAs serving as biomarkers in CRC.

METHODS

We performed lncRNA expression profiling using the lncRNA mining approach in large CRC cohorts from The Cancer Genome Atlas (TCGA) database. Receiver operating characteristic analysis was performed to identify the optimal cutoff point at which patients could be classified into the high-risk or low-risk groups. Based on the Cox coefficient of the individual lncRNAs, we identified a nine-lncRNA signature that was associated with the survival of CRC patients in the training set (n = 175). The prognostic value of this nine-lncRNA signature was validated in the testing set (n = 174) and TCGA set (n = 349). The prognostic models, consisting of these nine CRC-specific lncRNAs, performed well for risk stratification in the testing set and TCGA set. Time-dependent receiver operating characteristic analysis indicated that this predictive model had good performance.

RESULTS

Multivariate Cox regression and stratification analysis demonstrated that this nine-lncRNA signature was independent of other clinical features in predicting overall survival. Functional enrichment analysis of Kyoto Encyclopedia of Genes and Genomes pathways and Gene Ontology terms further indicated that these nine prognostic lncRNAs were closely associated with carcinogenesis-associated pathways and biological functions in CRC.

CONCLUSION

A nine-lncRNA expression signature was identified and validated that could improve the prognosis prediction of CRC, thereby providing potential prognostic biomarkers and efficient therapeutic targets for patients with CRC.

LncRNAs with miRNAs in regulation of gastric, liver, and colorectal cancers: updates in recent years

Long noncoding RNA (lncRNA) is a kind of RNAi molecule composed of hundreds to thousands of nucleotides. There are several major types of functional lncRNAs which participate in some important cellular pathways. LncRNA-RNA interaction controls mRNA translation and degradation or serves as a microRNA (miRNA) sponge for silencing. LncRNA-protein interaction regulates protein activity in transcriptional activation and silencing. LncRNA guide, decoy, and scaffold regulate transcription regulators of enhancer or repressor region of the coding genes for alteration of expression. LncRNA plays a role in cellular responses including the following activities: regulation of chromatin structural modification and gene expression for epigenetic and cell function control, promotion of hematopoiesis and maturation of immunity, cell programming in stem cell and somatic cell development, modulation of pathogen infection, switching glycolysis and lipid metabolism, and initiation of autoimmune diseases. LncRNA, together with miRNA, are considered the critical elements in cancer development. It has been demonstrated that tumorigenesis could be driven by homeostatic imbalance of lncRNA/miRNA/cancer regulatory factors resulting in biochemical and physiological alterations inside the cells. Cancer-driven lncRNAs with other cellular RNAs, epigenetic modulators, or protein effectors may change gene expression level and affect the viability, immortality, and motility of the cells that facilitate cancer cell cycle rearrangement, angiogenesis, proliferation, and metastasis. Molecular medicine will be the future trend for development. LncRNA/miRNA could be one of the potential candidates in this category. Continuous studies in lncRNA functional discrepancy between cancer cells and normal cells and regional and rational genetic differences of lncRNA profiles are critical for clinical research which is beneficial for clinical practice.

Long non-coding RNA HOTTIP is upregulated in renal cell carcinoma and regulates cell growth and apoptosis by epigenetically silencing of LATS2

Renal cell carcinoma (RCC) is one of the most aggressive malignancies with increasing incidence worldwide and is characterized by dismal prognosis owing to a lack of early detection and prognostic biomarkers for this fatal disease. Accumulating studies demonstrated that abnormally expressed long non-coding RNAs (lncRNAs) are involved in tumorigenesis and progression. Specifically, HOTTIP is upregulated and exerts oncogenic properties in some cancers. However, its clinical significance, biological functions and molecular mechanisms in RCC have not been studied. In the current study, RT-qPCR was performed to quantify the relative expression of HOTTIP in RCC tissues and cells. Additionally, we explored its clinical value using Fisher's exact test. Moreover, cell growth and apoptosis altered by HOTTIP was evaluated in vitro and in vivo. Mechanistically, RNA immunoprecipitation (RIP) and chromatin immunoprecipitation (ChIP) analysis was used to determine its molecular mechanism in cell growth and apoptosis. As a result, upregulated HOTTIP is closely associated with unfavorable phenotypes in RCC patients. The mechanistic investigations showed that HOTTIP could bind to enhancer of zeste homolog 2 (EZH2) and lysine specific demethylase 1 (LSD1), thereby repressing LATS2 expression. Collectively, our study illustrates how HOTTIP plays an oncogenic role in RCC and may offer a potential therapeutic target for treating this fatal disease.

Weak sharing of genetic association signals in three lung cancer subtypes: evidence at the SNP, gene, regulation, and pathway levels

BACKGROUND

There are two main types of lung cancer: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). NSCLC has many subtypes, but the two most common are lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). These subtypes are mainly classified by physiological and pathological characteristics, although there is increasing evidence of genetic and molecular differences as well. Although some work has been done at the somatic level to explore the genetic and biological differences among subtypes, little work has been done that interrogates these differences at the germline level to characterize the unique and shared susceptibility genes for each subtype.

METHODS

We used single-nucleotide polymorphisms (SNPs) from a genome-wide association study (GWAS) of European samples to interrogate the similarity of the subtypes at the SNP, gene, pathway, and regulatory levels. We expanded these genotyped SNPs to include all SNPs in linkage disequilibrium (LD) using data from the 1000 Genomes Project. We mapped these SNPs to several lung tissue expression quantitative trait loci (eQTL) and enhancer datasets to identify regulatory SNPs and their target genes. We used these genes to perform a biological pathway analysis for each subtype.

RESULTS

We identified 8295, 8734, and 8361 SNPs with moderate association signals for LUAD, LUSC, and SCLC, respectively. Those SNPs had p < 1 × 10^{- 3} in the original GWAS or were within LD (r² > 0.8, Europeans) to the genotyped SNPs. We identified 215, 320, and 172 disease-associated genes for LUAD, LUSC, and SCLC, respectively. Only five genes (CHRNA5, IDH3A, PSMA4, RP11-650 L12.2, and TBC1D2B) overlapped all subtypes. Furthermore, we observed only two pathways from the Kyoto Encyclopedia of Genes and Genomes shared by all subtypes. At the regulatory level, only three eQTL target genes and two enhancer target genes overlapped between all subtypes.

CONCLUSIONS

Our results suggest that the three lung cancer subtypes do not share much genetic signal at the SNP, gene, pathway, or regulatory level, which differs from the common subtype classification based upon histology. However, three (CHRNA5, IDH3A, and PSMA4) of the five genes shared between the subtypes are well-known lung cancer genes that may act as general lung cancer genes regardless of subtype.

Long noncoding RNA CCAT1 polymorphisms are associated with the risk of colorectal cancer

Colorectal cancer associated transcript 1 (CCAT1) is a novel long noncoding RNA, whose overexpression is evident in both early phase of tumorigenesis and later disease stages in colorectal cancer (CRC). No study has explored the relationship between CCAT1 polymorphisms and CRC risk. In the present study, a case-control study was conducted to investigate the association between CCAT1 polymorphisms and CRC risk in Chinese population. We identified that CCAT1 rs67085638 polymorphism was associated with an increased risk of CRC (OR = 1.72, 95%CI = 1.14-2.58, P = 0.009 in heterozygote codominant model; OR = 1.67, 95%CI = 1.13-2.47, P = 0.010 in dominant model). Moreover, CCAT1 rs7013433 polymorphism was associated with late clinical stage (OR = 1.82, 95%CI = 1.16-2.86, P = 0.009 in heterozygote codominant model; OR = 1.72, 95%CI = 1.13-2.63, P = 0.012 in dominant model). Our finding proposed a link between CCAT1 polymorphisms with CRC risk as well as different clinical stages.