Loss of Fbxw7 expression is a predictor of recurrence in colorectal liver metastasis

Biallelic FBXW7 knockout induces AKAP8-mediated DNA damage in neighbouring wildtype cells

Colorectal cancer possesses marked intratumoral heterogeneity. While subclonal interactions between Vogelstein driver mutations have been extensively studied, less is known about competitive or cooperative effects between subclonal populations with other cancer driver mutations. FBXW7 is a cancer driver mutation which is present in close to 17% of colorectal cancer cells. In this study, we generated isogenic FBXW7 mutant cells using CRISPR-Cas9. We identified an upregulation of oxidative phosphorylation and DNA damage in FBXW7 mutant cells, which surprisingly proliferated at a decreased rate compared to wildtype cells. To determine subclonal interactions, wildtype and mutant FBXW7 cells were cocultured using a Transwell system. Wildtype cells cocultured with FBXW7 mutant cells similarly developed DNA damage which was not observed when wildtype cells were co-cultured with other wildtype cells, suggesting that FBXW7 mutant cells were inducing DNA damage in neighbouring wildtype cells. Using mass spectrometry, we identified AKAP8 as being secreted by FBXW7 mutant cells into the coculture media. Furthermore, overexpression of AKAP8 in wildtype cells recapitulated the DNA damage phenotype observed during coculture, while co-culture of wildtype cells with double mutant FBXW7^-/-/AKAP8^-/- cells abrogated the DNA damage phenotype. Here, we describe a hitherto unknown phenomenon of AKAP8-mediated DNA damage from FBXW7 mutant to neighbouring wildtype cells. Our findings demonstrate the importance of elucidating the local effect of cancer driver mutations between subclonal populations.

Association of single nucleotide polymorphism miRNA-146a (rs2910164) with increased predisposition to oral squamous cell carcinoma in central India population

BACKGROUND

miRNAs play a crucial role in the genesis of cancer, either as tumor suppressor genes or as oncogenes. Single Nucleotide Polymorphisms (SNPs) in the seed region of microRNAs (miRNAs) can dysregulate their levels in the tissues and thereby affect carcinogenesis. The association of SNP in miR-146a (rs2910164) with the risk of oral squamous cell carcinoma (OSCC) has not been understood.

OBJECTIVE

In the present study, we have determined the association and functional significance of miR-146a (rs2910164) SNP with susceptibility to OSCC predisposition.

METHODS

In the present case-control study, we enrolled 430 subjects from central India (215 OSCC cases and 215 healthy controls). We performed genotyping by Kompetitive Allele Specific PCR (KASP), and their correlation with OSCC susceptibility was analyzed. miRNA expression profiling in tumor tissues and adjacent normal tissues from six OSCC patients was done by a NanoString n-Counter-based assay. Subsequently, gene ontology and pathway analysis were performed with FunRich version 3.13.

RESULTS

The CC genotype of rs2910164 miR-146a was significantly associated with the increased risk for OSCC (CC vs GC, OR = 2.62; 95% CI: 1.48-4.66; p value = 0.001). However, the GC genotype was protective with GC vs CC (OR = 0.38, 95%CI =0.21-0.67, p-value = 0.001), and GC vs GG (OR = 0.58, 95%CI = 0.37-0.89, p-value = 0.01).

CONCLUSION

Our finding suggests that SNP rs2910164 of miR-146a may be a genetic risk factor for OSCC susceptibility in the Central India population. However, more extensive multicenter studies are required to validate these findings.

FBXW7 and the Hallmarks of Cancer: Underlying Mechanisms and Prospective Strategies

FBXW7, a member of the F-box protein family within the ubiquitin–proteasome system, performs an indispensable role in orchestrating cellular processes through ubiquitination and degradation of its substrates, such as c-MYC, mTOR, MCL-1, Notch, and cyclin E. Mainly functioning as a tumor suppressor, inactivation of FBXW7 induces the aberrations of its downstream pathway, resulting in the occurrence of diseases especially tumorigenesis. Here, we decipher the relationship between FBXW7 and the hallmarks of cancer and discuss the underlying mechanisms. Considering the interplay of cancer hallmarks, we propose several prospective strategies for circumventing the deficits of therapeutic resistance and complete cure of cancer patients.

Clinical significance of FBXW7 tumor suppressor gene mutations and expression in human colorectal cancer: a systemic review and meta-analysis

BACKGROUND

Various studies investigating the clinical significance of FBXW7 mutation and/or expression have yielded inconclusive results in colorectal cancer (CRC) patients. Therefore, the present meta-analysis summarizes previous evidence and evaluates the clinical significance, including the prognostic role, of FBXW7 status in CRCs.

METHODS

The meta-analysis was conducted by searching the databases of PubMed, China National Knowledge Infrastructure (CNKI), WANFANG data, Web of Science, Embase, and Web of Science. Pooled odds ratios (ORs) and hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) were calculated to assess the relationships between FBXW7 status and clinicopathological features and survival in CRC, respectively.

RESULTS

Ten studies involving 4199 patients met the inclusion criteria and included in our meta-analysis. FBXW7 mutation/low expression was obviously correlated with advanced T stage (OR = 0.44, 95% CI: 0.27-0.74, P <  0.01) and lymph node metastasis (OR = 1.88, 95% CI: 1.40-2.53, P <  0.01), but was not associated with other parameters. Further investigation found that FBXW7 mutation/low expression predicted poor OS (HR = 1.25, 95% CI: 1.06-1.47, P <  0.01), but not DFS in CRC (HR = 1.04, 95% CI: 0.60-1.82, P = 0.88). Subgroup analysis found that FBXW7 status was obviously correlated with OS in cohorts recruited after 2009 (HR = 1.32, 95% CI: 1.17-1.50, P <  0.01), from eastern Asia (HR = 1.27, 95% CI: 1.04-1.55, P = 0.02), detected by immunohistochemistry/qRT-PCR (HR = 1.39, 95% CI: 1.22-1.59, P <  0.01), and analysed with multivariate method (HR = 1.47, 95% CI: 1.25-1.74, P <  0.01).

CONCLUSIONS

This study indicates that FBXW7 status, expression level especially, is associated with OS but not DFS in CRC. FBXW7 expression level may function as a prognostic biomarker in CRC.

Emerging Mechanisms and Treatment Progress on Liver Metastasis of Colorectal Cancer

Colorectal cancer is currently the third largest malignant tumor in the world, with high new cases and high mortality. Metastasis is one of the most common causes of death of colorectal cancer, of which liver metastasis is the most fatal. Since the beginning of the Human Genome Project in 2001, people have gradually recognized the 3 billion base pairs that make up the human genome, of which only about 1.5% of the nucleic acid sequences are used for protein coding, including proto-oncogenes and tumor suppressor genes. A large number of differences in the expression of proto-oncogenes and tumor suppressor genes have also been found in the study of colorectal cancer, which proves that they are also actively involved in the progression of colorectal cancer and promote the occurrence of liver metastasis. Except for 1.5% of the coding sequence, the rest of the nucleic acid sequence does not encode any protein, which is called non-coding RNA. With the deepening of research, genome sequences without protein coding potential that were originally considered “junk sequences” may have important biological functions. Many years of studies have found that a large number of abnormal expression of ncRNA in colorectal cancer liver metastasis, indicating that ncRNA plays an important role in it. To explore the role and mechanism of these coding sequences and non-coding RNA in liver metastasis of colorectal cancer is very important for the early diagnosis and treatment of liver metastasis of colorectal cancer. This article reviews the coding genes and ncRNA that have been found in the study of liver metastasis of colorectal cancer in recent years, as well as the mechanisms that have been identified or are still under study, as well as the clinical treatment of liver metastasis of colorectal cancer.

MicroRNA‑223‑induced inhibition of the FBXW7 gene affects the proliferation and apoptosis of colorectal cancer cells via the Notch and Akt/mTOR pathways

The tumour suppressor gene F-box and WD repeat domain-containing 7 (FBXW7) plays an important role in human cancer by regulating cell division, proliferation and differentiation. However, the exact regulatory mechanisms of microRNA (miR)-223 in colorectal cancer (CRC) cells are still unknown. The present study aimed to investigate the effect and mechanism of miR-223 inhibiting FBXW7 on the proliferation and apoptosis of CRC cells. HCT116 cells were transfected with miR-223 mimics or small interfering RNA (siRNA) targeting FBXW7 (siFBXW7), and the effects of these treatments on cell proliferation and apoptosis were examined. The downstream Notch and Akt/mTOR pathways were also assessed. Following miR-223 overexpression, the mRNA and protein expression levels of FBXW7 were downregulated. Transfection with miR-223 mimics or siFBXW7 promoted the proliferation of HCT116 cells and inhibited apoptosis by promoting the Notch and Akt/mTOR signalling pathways. Conversely, miR-223 mimics transfection with FBXW7 overexpression inhibited cell viability and restored apoptosis. Thus, the present study demonstrated that miR-223 could bind to the FBXW7 gene and inhibit its expression, ultimately increasing the proliferation and preventing the apoptosis of CRC cells through the Notch and Akt/mTOR signalling pathways.