FAM46C inhibits cell proliferation and cell cycle progression and promotes apoptosis through PTEN/AKT signaling pathway and is associated with chemosensitivity in prostate cancer

Dissecting the Puzzling Roles of FAM46C: A Multifaceted Pan-Cancer Tumour Suppressor with Increasing Clinical Relevance

FAM46C is a well-established tumour suppressor with a role that is not completely defined or universally accepted. Although FAM46C expression is down-modulated in several tumours, significant mutations in the FAM46C gene are only found in multiple myeloma (MM). Consequently, its tumour suppressor activity has primarily been studied in the MM context. However, emerging evidence suggests that FAM46C is involved also in other cancer types, namely colorectal, prostate and gastric cancer and squamous cell and hepatocellular carcinoma, where FAM46C expression was found to be significantly reduced in tumoural versus non-tumoural tissues and where FAM46C was shown to possess anti-proliferative properties. Accordingly, FAM46C was recently proposed to function as a pan-cancer prognostic marker, bringing FAM46C under the spotlight and attracting growing interest from the scientific community in the pathways modulated by FAM46C and in its mechanistic activity. Here, we will provide the first comprehensive review regarding FAM46C by covering (1) the intracellular pathways regulated by FAM46C, namely the MAPK/ERK, PI3K/AKT, β-catenin and TGF-β/SMAD pathways; (2) the models regarding its mode of action, specifically the poly(A) polymerase, intracellular trafficking modulator and inhibitor of centriole duplication models, focusing on connections and interdependencies; (3) the regulation of FAM46C expression in different environments by interferons, IL-4, TLR engagement or transcriptional modulators; and, lastly, (4) how FAM46C expression levels associate with increased/decreased tumour cell sensitivity to anticancer agents, such as bortezomib, dexamethasone, lenalidomide, pomalidomide, doxorubicin, melphalan, SK1-I, docetaxel and norcantharidin.

A combined in vitro and molecular dynamics simulation studies unveil the molecular basis of the anticancer potential of piperine targeting AKT1 against prostate cancer

The present study investigates the activity of the natural compound piperine on prostate cancer cell line (PC-3), followed by exploring its mechanistic inhibition on the RAC-alpha serine/threonine-protein kinase (AKT1) protein. The 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay showed that after 24 hrs of exposure to piperine (15 µmol/ml), cell viability fell to 50% compared to the standard drug flutamide (SDF) (51 µmol/ml) with a lower IC50 concentration. However, the Dual acridine orange/ethidium bromide (AO/EtBr) staining demonstrated that, as compared to the SDF, piperine caused substantial cellular death in PC-3 cells, presumably by triggering DNA fragmentation. In addition, compared to untreated cells, the proportion of the sub-G0/G1 and G2/M stages population increased considerably in piperine-treated cells. The cell cycle's sub-G0/G1 and G2/M phases were also arrested in piperine-treated cells compared to the SDF in cell cycle analysis. Based on our systems pharmacology and molecular docking studies, AKT1 is predicted as a potential target against piperine. The complementary charge between AKT1 and piperine was emphasized in the transient ligand-protein binding interaction in molecular dynamic modeling over 100 ns, and stable hydrogen bond interaction between Lys268 and Ser205 amino acid residues of the active pocket was hypothesized. Overall, the findings from our in vitro and MD simulations provide insights into the mechanism of piperine targeting AKT1 and offer a possible candidate for future prostate cancer therapeutic development.Communicated by Ramaswamy H. Sarma.

Heme Metabolism-Related Gene TENT5C is a Prognostic Marker and Investigating Its Immunological Role in Colon Cancer

Background

There is a strong correlation between consuming high amounts of heme and an elevated risk of developing various types of cancer, including colorectal cancer. However, the role of heme metabolism-related genes (HRGs) in colorectal cancer remains unclear. Our study aimed to identify prognostic markers for colorectal cancer patients based on these genes.

Methods

The heme metabolism score was assessed using gene set variation analysis (GSVA). Potential prognostic HRGs were identified from the TCGA-COAD dataset using LASSO and COX regression analyses. The expression level of TENT5C was validated in the GEO database and clinical samples. To explore the association between TENT5C expression and immune cell infiltrations, we performed ESTIMATE and single-sample gene set enrichment analysis (ssGSEA).

Results

The low level of heme metabolism score was associated with a poor prognosis in colorectal cancer patients. TENT5C is a prognostic gene and an independent prognostic biomarker for overall survival. Its expression was confirmed in multiple datasets and clinical samples, showing a positive correlation with immune cells and immune score. GSEA results suggested TENT5C's significant role in regulating immune and inflammatory responses in colorectal cancer.

Conclusion

TENT5C can be used as a biomarker in colorectal cancer. Additionally, TENT5C is associated with both prognosis and immune infiltration. These findings lay a strong groundwork for future research to delve into the specific role of TENT5C in the development and advancement of colorectal cancer.

FAM46C Is an Interferon-Stimulated Gene That Inhibits Lentiviral Particle Production by Modulating Autophagy

FAM46C is a multiple myeloma (MM) tumor suppressor whose function is only starting to be elucidated. We recently showed that in MM cells FAM46C triggers apoptosis by inhibiting autophagy and altering intracellular trafficking and protein secretion. To date, both a physiological characterization of FAM46C role and an assessment of FAM46C-induced phenotypes outside of MM are lacking. Preliminary reports suggested an involvement of FAM46C with regulation of viral replication, but this was never confirmed. Here, we show that FAM46C is an interferon-stimulated gene and that the expression of wild-type FAM46C in HEK-293T cells, but not of its most frequently found mutant variants, inhibits the production of both HIV-1-derived and HIV-1 lentiviruses. We demonstrate that this effect does not require transcriptional regulation and does not depend on inhibition of either global or virus-specific translation but rather mostly relies on FAM46C-induced deregulation of autophagy, a pathway that we show to be required for efficient lentiviral particle production. These studies not only provide new insights on the physiological role of the FAM46C protein but also could help in implementing more efficient antiviral strategies on one side and lentiviral particle production approaches on the other. IMPORTANCE FAM46C role has been thoroughly investigated in MM, but studies characterizing its role outside of the tumoral environment are still lacking. Despite the success of antiretroviral therapy in suppressing HIV load to undetectable levels, there is currently no HIV cure, and treatment is lifelong. Indeed, HIV continues to be a major global public health issue. Here, we show that FAM46C expression in HEK-293T cells inhibits the production of both HIV and HIV-derived lentiviruses. We also demonstrate that such inhibitory effect relies, at least in part, on the well-established regulatory role that FAM46C exerts on autophagy. Deciphering the molecular mechanism underlying this regulation will not only facilitate the understanding of FAM46C physiological role but also give new insights on the interplay between HIV and the cellular environment.

Hsa-miR-1269a up-regulation fosters the malignant progression of esophageal squamous cell carcinoma via targeting FAM46C

Esophageal squamous cell carcinoma (ESCC) is a malignancy of the alimentary tract resulting in death worldwide. The role and underlying mechanism of hsa-miR-1269a in the progression of ESCC remain unclear. In this study, hsa-miR-1269a was screened by differential expression analysis in TCGA, and its target gene FAM46C was predicted. qRT-PCR was conducted to assay the expression of hsa-miR-1269a and FAM46C in ESCC cells. The results showed that hsa-miR-1269a was upregulated in ESCC tissues and cell lines. Hsa-miR-1269a overexpression stimulated the proliferation, migration, and invasion capacities of ESCC cells, and FAM46C overexpression inhibited these phenotypes. Dual-luciferase assay verified that hsa-miR-1269a could target FAM46C. Next, qRT-PCR and western blot demonstrated that hsa-miR-1269a overexpression downregulated FAM46C. Rescue experiments revealed that hsa-miR-1269a accelerated the malignant progression of ESCC through FAM46C down-regulation. These results indicate that the interaction between hsa-miR-1269a and FAM46C plays a regulatory role in driving the malignant progression of ESCC cells, thereby providing a novel molecular mechanism for understanding ESCC.

FAM126A interacted with ENO1 mediates proliferation and metastasis in pancreatic cancer via PI3K/AKT signaling pathway

Pancreatic cancer (PC) is a common digestive system carcinoma with high mortality rate mostly due to aberrant growth and distant metastasis. Current researches demonstrated that Family Sequence Similarities (FAMs) have been involving in tumor development, and which subfamily has the function of promoting or inhibiting tumors and its in-depth molecular mechanism remains unclear. Based on the Gene Expression Omnibus (GEO), the Gene Expression Profiling Interactive Analysis (GEPIA2), we observed that FAM126A is in high expressed level among PC tissues and contributes to worse progression of PC, which was validated by PC tissue microarray. Function assay indicated that overexpression of FAM126A accelerates PC cell proliferation, invasion and migration in vitro, as well as liver cancer metastasis in vivo. Further, we found that FAM126A induces epithelial-mesenchymal transition (EMT), including the downregulation of E-cadherin epithelial marker expression, and the upregulation of N-cadherin, Vimentin, and Snail, mesenchymal marker expression. By co-localization and co-immunoprecipitation assays, we confirmed that FAM126A directly interacts with ENO1, which was a key activator of the PI3K/AKT signaling pathway. Furthermore, ENO1 knockdown reversed cell proliferation, migration, and invasion of PC cells promoted by FAM126A overexpression in vitro and in vivo. In general, these results verified FAM126A is an oncogene interacting with ENO1 in PC by activating PI3K/AKT signaling pathway.

Overexpression of microRNA-107 suppressed proliferation, migration, invasion, and the PI3K/Akt signaling pathway and induced apoptosis by targeting Nin one binding (NOB1) protein in a hypopharyngeal squamous cell carcinoma cell line (FaDu)

Hypopharyngeal squamous cell carcinoma (HSCC) is one of the most common head and neck cancers, with a worst prognosis owing to its aggressivity. MicroRNA-107 (miR-107) is reported to regulate the progression of various cancers. Nevertheless, its implied function in HSCC remains unclear. This study is aimed to exploring the roles and potential mechanisms of miR-107 in HSCC. We found that miR-107 expression was significantly decreased in HSCC tissues compared with the para-cancer tissues. Moreover, miR-107 overexpression by miR-107 mimics decreased FaDu cell viability, led to cell cycle arrest in G1/S phase, accelerated apoptosis, and reduced cell migration and invasion. MiR-107 possibly resulted in deactivation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, evidenced by the decrease of phosphorylated (p-) PI3K and p-Akt. Besides, dual-luciferase reporter assay confirmed that miR-107 might bind to the 3’UTR of Nin one binding protein 1 (NOB1), and elevated NOB1 expression in HSCC tissues and a negative correlation between miR-107 and NOB1 were found. Rescue assays demonstrated the significant roles of miR-107 in FaDu cell behavior by modulating NOB1. In addition, the tumorigenic potential of miR-107 in vivo was conducted. It was found that miR-107 overexpression in FaDu cells significantly inhibited tumor growth and led to inactivation of the PI3K/Akt signaling. The above findings revealed that miR-107 could suppress FaDu cell proliferation, migration, invasion and induced apoptosis by targeting NOB1 through the PI3K/Akt pathway, suggesting that miR-107/NOB1 axis may exert a key role in FaDu HSCC development.

FAM46C as a Potential Marker for Pan-Cancer Prognosis and Predicting Immunotherapeutic Efficacy

Background:FAM46C is a common mutated gene in tumours. A comprehensive understanding of the relationship between FAM46C expression and pan-cancer can guide clinical prognosis and broaden the immunotherapeutic targets.

Methods: Data from The Cancer Genome Atlas and Genotype-Tissue Expression (GTEx) databases were obtained, and gene expression of different tumour types and stages was analysed. Immunohistochemical analysis was performed to detect differences in the FAM46C protein levels in normal and cancerous tissues. The genetic variation of FAM46C was characterised using cBioPortal. The clinical prognostic value of FAM46C and the impact of FAM46C expression levels on the prognosis of patients with different types of cancer were assessed based on Kaplan–Meier and Cox regression analyses. Gene set enrichment analysis (GSEA) was used to analyse the pathways associated with FAM46C. Correlations between FAM46C expression levels and immune infiltration were assessed using the TIMER2 database and CIBERSORT algorithm, and correlations between FAM46C expression and the ESTIMATE, immune and stromal scores were analysed using the ESTIMATE algorithm. In addition, we also analysed the correlation between FAM46C expression and immune activation, suppression genes and immune chemokines.

Results: The expression level of FAM46C was correlated with the prognosis of most tumours, and low expression levels often suggested a poor prognosis. FAM46C was positively correlated with the abundance of CD4+ T cells, CD8+ T cells and plasma B lymphocytes in the tumour microenvironment. FAM46C exhibited a strong correlation with immunomodulatory pathways, immunomodulatory factors and immune markers. In addition, high FAM46C expression correlated with tumour mutational burden in acute myeloid leukaemia and microsatellite instability in endometrial cancer.

Conclusion: Our study suggests that FAM46C can be a potential prognostic marker for pan-cancer, is closely associated with immune regulation and may be an immune checkpoint to guide future clinical immunotherapy.

Structural and functional characterization of multiple myeloma associated cytoplasmic poly(A) polymerase FAM46C

Background

Multiple myeloma (MM) is a hematologic malignancy characterized by the accumulation of aberrant plasma cells within the bone marrow. The high frequent mutation of family with sequence similarity 46, member C (FAM46C) is closely related with the occurrence and progression of MM. Recently, FAM46C has been identified as a non‐canonical poly(A) polymerase (PAP) that functions as a tumor suppressor in MM. This study aimed to elucidate the structural features of this novel non‐canonical PAP and how MM‐related mutations affect the structural and biochemical properties of FAM46C, eventually advancing our understandings towards FAM46C mutation‐related MM occurrence.

Methods

We purified and crystallized a mammalian FAM46C construct, and solved its structure. Next, we characterized the property of FAM46C as a PAP through a combination of structural analysis, site‐directed mutagenesis and biochemical assays, and by comparison with its homolog FAM46B. Finally, we structurally analyzed MM‐related FAM46C mutations and tested the enzymatic activity of corresponding mutants.

Results

We determined the crystal structure of a mammalian FAM46C protein at 2.35 Å, and confirmed that FAM46C preferentially consumed adenosine triphosphate (ATP) and extended A‐rich RNA substrates. FAM46C showed a weaker PAP activity than its homolog FAM46B, and this difference was largely dependent on the residue variance at particular sites. Of them, residues at positions 77, 290, and 298 of mouse FAM46C were most important for the divergence in enzymatic activity. Among the MM‐associated FAM46C mutants, those residing at the catalytic site (D90G and D90H) or putative RNA‐binding site (I155L, S156F, D182Y, F184L, Y247V, and M270V) showed abolished or compromised PAP activity of FAM46C, while N72A and S248A did not severely affect the PAP activity. FAM46C mutants D90G, D90H, I155L, S156F, F184L, Y247V, and M270V had significantly lower inhibitory effect on apoptosis of RPMI‐8226 cells as compared to wild‐type FAM46C.

Conclusions

FAM46C is a prokaryotic‐like PAP with preference for A‐rich RNA substrates, and showed distinct enzymatic efficiency with its homolog FAM46B. The MM‐related missense mutations of FAM46C lead to various structural and biochemical outcomes to the protein.

MiR-221/222 Ameliorates Deoxynivalenol-Induced Apoptosis and Proliferation Inhibition in Intestinal Epithelial Cells by Targeting PTEN

Intestinal epithelial cells are critical for nutrient absorption and defending against pathogen infection. Deoxynivalenol (Don), the most common mycotoxin, contaminates cereals and food throughout the world, causes serious damage to mammal intestinal mucosa, and appears as intestinal epithelial cell apoptosis and proliferation inhibition. Our previous study has found that milk-derived exosome ameliorates Don-induced intestinal damage, but the mechanism is still not fully understood. In this study, we demonstrated that Don downregulated the expression of miR-221/222 in intestinal epithelial cells, and exosome treatment reversed the inhibitory effect of Don on miR-221/222. Through immunofluorescence and flow cytometry analysis, we identified that miR-221/222 ameliorates Don-induced apoptosis and proliferation inhibition in intestinal epithelial cells. Through bioinformatics analyses and RNA immunoprecipitation analysis, we identified Phosphatase and tensin homolog (PTEN) is the target of miR-221/222. Through the PTEN interfering experiment, we found Don-induced apoptosis and proliferation inhibition relied on PTEN. Finally, through adenovirus to overexpress miR-221/222 in mice intestinal epithelial cells specifically, our results showed that miR-221/222 ameliorated Don-induced apoptosis and proliferation inhibition in intestinal epithelial cells by targeting PTEN. This study not only expands our understanding of how miR-221/222 and the host gene PTEN regulate intestinal epithelial cells defending against Don-induced damage, but also provides a new way to protect the development of the intestine.

Recent advances in PTEN signalling axes in cancer

In over two decades since the discovery of phosphatase and tensin homologue deleted on chromosome 10 (PTEN), nearly 18,000 publications have attempted to elucidate its functions and roles in normal physiology and disease. The frequent disruption of PTEN in cancer cells was a strong indication that it had critical roles in tumour suppression. Germline PTEN mutations have been identified in patients with heterogeneous tumour syndromic diseases, known as PTEN hamartoma tumour syndrome (PHTS), and in some individuals with autism spectrum disorders (ASD). Today we know that by limiting oncogenic signalling through the phosphoinositide 3-kinase (PI3K) pathway, PTEN governs a number of processes including survival, proliferation, energy metabolism, and cellular architecture. Some of the most exciting recent advances in the understanding of PTEN biology and signalling have revisited its unappreciated roles as a protein phosphatase, identified non-enzymatic scaffold functions, and unravelled its nuclear function. These discoveries are certain to provide a new perspective on its full tumour suppressor potential, and knowledge from this work will lead to new anti-cancer strategies that exploit PTEN biology. In this review, we will highlight some outstanding questions and some of the very latest advances in the understanding of the tumour suppressor PTEN.

FAM46C and FNDC3A Are Multiple Myeloma Tumor Suppressors That Act in Concert to Impair Clearing of Protein Aggregates and Autophagy

Multiple myeloma is a plasma cell neoplasm characterized by the production of unfolded immunoglobulins, which cause endoplasmic reticulum (ER) stress and sensitivity to proteasome inhibition. The genomic landscape of multiple myeloma is characterized by the loss of several genes rarely mutated in other cancers that may underline specific weaknesses of multiple myeloma cells. One of these is FAM46C that is lost in more than 10% of patients with multiple myeloma. We show here that FAM46C is part of a new complex containing the ER-associated protein FNDC3A, which regulates trafficking and secretion and, by impairing autophagy, exacerbates proteostatic stress. Reconstitution of FAM46C in multiple myeloma cells that had lost it induced apoptosis and ER stress. Apoptosis was preceded by an increase of intracellular aggregates, which was not linked to increased translation of IgG mRNA, but rather to impairment of autophagy. Biochemical analysis showed that FAM46C requires interaction with ER bound protein FNDC3A to reside in the cytoplasmic side of the ER. FNDC3A was lost in some multiple myeloma cell lines. Importantly, depletion of FNDC3A increased the fitness of FAM46C-expressing cells and expression of FNDC3A in cells that had lost it recapitulated the effects of FAM46C, inducing aggregates and apoptosis. FAM46C and FNDC3A formed a complex that modulates secretion routes, increasing lysosome exocytosis. The cellular landscape generated by FAM46C/FNDC3A expression predicted sensitivity to sphingosine kinase inhibition. These results suggest that multiple myeloma cells remodel their trafficking machinery to cope with ER stress. SIGNIFICANCE: This study identifies a new multiple myeloma-specific tumor suppressor complex that regulates autophagy and unconventional secretion, highlighting the sensitivity of multiple myeloma cells to the accumulation of protein aggregates.

Progress in Delivery of siRNA-Based Therapeutics Employing Nano-Vehicles for Treatment of Prostate Cancer

Prostate cancer (PCa) accounts for a high number of deaths in males with no available curative treatments. Patients with PCa are commonly diagnosed in advanced stages due to the lack of symptoms in the early stages. Recently, the research focus was directed toward gene editing in cancer therapy. Small interfering RNA (siRNA) intervention is considered as a powerful tool for gene silencing (knockdown), enabling the suppression of oncogene factors in cancer. This strategy is applied to the treatment of various cancers including PCa. The siRNA can inhibit proliferation and invasion of PCa cells and is able to promote the anti-tumor activity of chemotherapeutic agents. However, the off-target effects of siRNA therapy remarkably reduce its efficacy in PCa therapy. To date, various carriers were designed to improve the delivery of siRNA and, among them, nanoparticles are of importance. Nanoparticles enable the targeted delivery of siRNAs and enhance their potential in the downregulation of target genes of interest. Additionally, nanoparticles can provide a platform for the co-delivery of siRNAs and anti-tumor drugs, resulting in decreased growth and migration of PCa cells. The efficacy, specificity, and delivery of siRNAs are comprehensively discussed in this review to direct further studies toward using siRNAs and their nanoscale-delivery systems in PCa therapy and perhaps other cancer types.