Expanding phenotype of hereditary fibrosing poikiloderma with tendon contractures, myopathy, and pulmonary fibrosis caused by FAM111B mutations: Report of an additional family raising the question of cancer predisposition and a short review of early-onset poikiloderma

Unravelling the Intricate Roles of FAM111A and FAM111B: From Protease-Mediated Cellular Processes to Disease Implications

Proteases are critical enzymes in cellular processes which regulate intricate events like cellular proliferation, differentiation and apoptosis. This review highlights the multifaceted roles of the serine proteases FAM111A and FAM111B, exploring their impact on cellular functions and diseases. FAM111A is implicated in DNA replication and replication fork protection, thereby maintaining genome integrity. Additionally, FAM111A functions as an antiviral factor against DNA and RNA viruses. Apart from being involved in DNA repair, FAM111B, a paralog of FAM111A, participates in cell cycle regulation and apoptosis. It influences the apoptotic pathway by upregulating anti-apoptotic proteins and modulating cell cycle-related proteins. Furthermore, FAM111B's association with nucleoporins suggests its involvement in nucleo-cytoplasmic trafficking and plays a role in maintaining normal telomere length. FAM111A and FAM111B also exhibit some interconnectedness and functional similarity despite their distinct roles in cellular processes and associated diseases resulting from their dysfunction. FAM111A and FAM111B dysregulation are linked to genetic disorders: Kenny-Caffey Syndrome type 2 and Gracile Bone Dysplasia for FAM111A and POIKTMP, respectively, and cancers. Therefore, the dysregulation of these proteases in diseases emphasizes their potential as diagnostic markers and therapeutic targets. Future research is essential to unravel the intricate mechanisms governing FAM111A and FAM111B and explore their therapeutic implications comprehensively.

Loss of FAM111B protease mutated in hereditary fibrosing poikiloderma negatively regulates telomere length

Hereditary fibrosing poikiloderma (HFP) is a rare human dominant negative disorder caused by mutations in the FAM111B gene that encodes a nuclear trypsin-like serine protease. HFP patients present with symptoms including skin abnormalities, tendon contractures, myopathy and lung fibrosis. We characterized the cellular roles of human FAM111B using U2OS and MCF7 cell lines and report here that the protease interacts with components of the nuclear pore complex. Loss of FAM111B expression resulted in abnormal nuclear shape and reduced telomeric DNA content suggesting that FAM111B protease is required for normal telomere length; we show that this function is independent of telomerase or recombination driven telomere extension. Even though FAM111B-deficient cells were proficient in DNA repair, they showed hallmarks of genomic instability such as increased levels of micronuclei and ultra-fine DNA bridges. When mutated as in HFP, FAM111B was more frequently localized to the nuclear envelope, suggesting that accumulation of the mutated protease at the nuclear periphery may drive the disease pathology.

High FAM111B expression predicts aggressive clinicopathologic features and poor prognosis in ovarian cancer

BACKGROUNDS

Ovarian cancer (OC) is the second most common gynecological tumor with the highest mortality rate worldwide. High FAM111B expression has been reported as a predictor of poor prognosis in other cancers, but its correlation with OC has not been reported.

METHODS

Immunohistochemistry of tissue microarrays was performed to detect FAM111B expression levels in 141 OC patient tissues. The prognostic value of FAM111B was determined by Kaplan-Meier survival analysis, and correlations between FAM111B expression and clinicopathologic features were investigated by the Clu-square test. The significance of FAM111B expression was verified bioinformatically using the Gene Expression Omnibus database. Protein-protein interaction were performed to explore downstream mechanisms of FAM111B in OC.

RESULTS

Among 141 OC patients, FAM111B was positively expressed in 87.23%, 58.16%, and 87.94%; and highly expressed in 8.51%, 17.02%, and 19.86%, as evaluated by cytoplasmic, nuclear, and combined cytoplasmic/nuclear staining. FAM111B expression was positively correlated with the expression of tumor protein markers KI67, EGFR, and PDL-1. Patients with high FAM111B expression had aggressive clinicopathologic features and shorter overall survival (P value 0.0428, 0.0050, 0.0029) and progression-free survival (P value 0.0251, 0.012, 0.0596) compared to the low FAM111B expression group for cytoplasmic, nuclear, and combined cytoplasmic/nuclear groups, respectively. These results were verified using patient data from the Gene Expression Omnibus. Seventeen genes co-expressed with FAM111B were primarily involved in "negative regulation of histone modification", "hippo signaling" and "inner ear receptor cell differentiation".

CONCLUSIONS

High FAM111B expression may serve as a novel prognostic predictor and molecular therapeutic target for OC.

Hereditary fibrosing poikiloderma (POIKTMP syndrome) report of a new mutation and review of the literature

Hereditary fibrosing poikiloderma with tendon contractures, myopathy, and pulmonary fibrosis (POIKTMP) is a genodermatosis with autosomal dominant inheritance caused by mutations in FAM111B. We report another case with a new pathogenic variant and analyze all previously published 34 cases with a focus on sequence of clinical presentation and genotype-phenotype correlation. POIKTMP is characterized by marked age-dependent clinical expressivity. FAM111B encodes a catalytic nuclear protein, expressed in many tissues, which contributes to impaired DNA repair affecting multiple systems. Specific inhibition of catalytic activity might be a future strategy to halt progression of this otherwise untreatable disease. Given the relentless progression of the disease, it would make sense to start such treatment as early as possible. In order to achieve this objective, children with suspected POIKTMP should therefore undergo early imaging of all relevant organ systems.

FAM111B dysregulation promotes malignancy in fibrosarcoma and POIKTMP and a low-cost method for its mutation screening

INTRODUCTION

Mutations in the uncharacterised human FAM111B gene are associated with POIKTMP, a rare multi-organ fibrosing disease. Recent studies also reported the overexpression of FAM111B in specific cancers. Moreover, FAM111B mutation screening may prove expensive in under-resourced facilities. Therefore, this study investigated its cellular function and dysfunction and described an inexpensive mutation screening method.

MATERIALS AND METHODS

FAM111B expression was assessed in silico and validated in vitro in cell lines and primary skin fibroblasts from a South African POIKTMP-patient with the heterozygous FAM111B gene mutation: NM_198947.4: c.1861T>G (p. Tyr621Asp or Y621D) by qPCR and western blot. The cellular function of FAM111B was studied in HT1080 using various cell-based functional assays, and the Y621D mutation was genotyped by PCR-RFLP.

RESULTS

Expression studies showed upregulated FAM111B mRNA and protein in the cancer cells. High FAM111B expression with robust nuclear localization occurred in HT1080. Additionally, expression data and cell-based assays indicated that FAM111B led to the upregulation of cell migration, decreased cell apoptosis, and modulatory effects on cell proliferation. Y621D mutation showed similar effects on cell migration but minimal impact on cell apoptosis. FAM111B mRNA and protein expression were markedly downregulated (p ≤ 0.05) in the POIKTMP-patient's fibroblasts. The PCR-RFLP method successfully genotyped Y621D gene mutation.

DISCUSSION

FAM111B is a cancer-associated nuclear protein: Its modulation by mutations or overexpression may contribute to the malignancy of cancers and POIKTMP/fibrosis and poor clinical outcomes and represents a viable prognostic marker or therapeutic target. Furthermore, the PCR-RFLP method could prove a valuable tool for FAM111B mutation validation or screening in resource-constrained laboratories.

Pan-Cancer Analysis of the Tumorigenic Effect and Prognostic Diagnostic Value of FAM111B in Human Carcinomas

Introduction

FAM111B (FAM111 trypsin-like peptidase B) gene mutations have been linked to a hereditary fibrosing poikiloderma disorder known to cause poikiloderma, tendon contracture, myopathy, and pulmonary fibrosis (POIKTMP). Overexpression of FAM111B has been associated with an increased risk of certain cancers with a poor prognosis, although the relationship between FAM111B and other tumors is still unclear, and the molecular mechanism of its action is not fully understood.

Methods

We investigated the biological functions of FAM111B in 33 solid tumors using multi-omics data. We further recruited 109 gastric cancer (GC) patients for a clinical cohort study to confirm the effect of FAM111B on early tumor recurrence. Furthermore, we assessed the role of FAM111B in GC cell proliferation and migration via EdU incorporation, CCK8 and transwell assays in vitro.

Results

We found that FAM111B can enhance oncogenesis and progression in multiple tumor types. The clinical cohort of GC showed that upregulation of FAM111B is associated with early recurrence of GC, and knockdown of the FAM111B gene can inhibit the proliferation and migration of GC cells. Gene enrichment analysis indicates that FAM111B promotes cancer through immune system process, chromosome instability, DNA repair, and apoptosis regulation. Mechanistically, FAM111B appears to promote the growth cycle of malignant tumor cells while inhibiting apoptosis.

Conclusion

FAM111B may serve as a potential pan-cancer biomarker for predicting the prognosis and survival of malignant tumor patients. Our study elucidates the role of FAM111B in the occurrence and development of various cancers, and highlights the need for future research on FAM111B in cancers.

A cost-effective method for detecting mutations in the human FAM111B gene associated with POIKTMP syndrome

Background

Mutations of the human FAM111B gene are associated with hereditary fibrosing poikiloderma with tendon contracture, myopathy, and pulmonary fibrosis (POIKTMP), a rare and autosomal dominant multi-systemic fibrosing disease. To date, a total of 36 cases are documented, with eleven associated mutations identified and confirmed by Whole-Exome Sequencing and Sanger sequencing. However, these methods require a certain level of expertise. The FAM111B gene was annotated using the SNAPGENE tool to identify various restriction enzymes. The enzymes that cut at the positions where mutations of interest have been reported were selected. The method was implemented using the DNA samples extracted from the skin fibroblast collected from an affected South African family and unrelated control.

Results

The findings showed that of the eleven FAM111B mutational sites investigated with this method, ten mutations can be identified including the known mutation FAM111B NM_198947.4: c.1861T>G (pTyr621Asp) associated with the POIKTMP in South Africa.

Conclusions

Limited access to molecular diagnosis contributes to why POIKTMP is rarely diagnosed. Our study describes an inexpensive PCR–RFLP method to screen for POIKTMP FAM111B gene mutations. The PCR–RFLP can be used as a cost-effective method for diagnosing FAM111B mutations in POIKTMP, and it does not require having robust experience in molecular biology.

Functions and evolution of FAM111 serine proteases

Proteolysis plays fundamental and regulatory roles in diverse cellular processes. The serine protease FAM111A (FAM111 trypsin-like peptidase A) emerged recently as a protease involved in two seemingly distinct processes: DNA replication and antiviral defense. FAM111A localizes to nascent DNA and plays a role at the DNA replication fork. At the fork, FAM111A is hypothesized to promote DNA replication at DNA-protein crosslinks (DPCs) and protein obstacles. On the other hand, FAM111A has also been identified as a host restriction factor for mutants of SV40 and orthopoxviruses. FAM111A also has a paralog, FAM111B, a serine protease with unknown cellular functions. Furthermore, heterozygous missense mutations in FAM111A and FAM111B cause distinct genetic disorders. In this review, we discuss possible models that could explain how FAM111A can function as a protease in both DNA replication and antiviral defense. We also review the consequences of FAM111A and FAM111B mutations and explore possible mechanisms underlying the diseases. Additionally, we propose a possible explanation for what drove the evolution of FAM111 proteins and discuss why some species have two FAM111 proteases. Altogether, studies of FAM111 proteases in DNA repair, antiviral defense, and genetic diseases will help us elucidate their functions and the regulatory mechanisms.

Expanding phenotype of FAM111B-related disease focusing on liver involvement: Literature review, report of a case with end-stage liver disease and proposal for a new acronym

POIKiloderma, tendon contractures, myopathy, pulmonary fibrosis is a congenital multisystem disorder due to FAM111B dominant variants. We present a literature review focusing on the frequency and the impact of hepatic involvement and a case report of a patient with severe end-stage liver disease. Whole exome sequencing (WES) was conducted on the proband and his parents. A de novo FAM111B: c.1879A > G; (p.Arg627Gly) variant was identified. Hepatic involvement is present in 11 out of the 30 patients described in the literature, with different levels of dysfunction ranging from mild transaminitis to liver fibrosis found in three different cases by liver biopsies. Liver involvement seems to be a significant cause of morbidity. We propose to modify the previous acronym in POIK-TMPL: including POIKiloderma, tendon contractures, myopathy, pulmonary fibrosis/pancreas insufficiency and cancer, liver involvement/lymphedema. Moreover, we suggest screening patients with FAM111B variants for liver involvement from the first month of life and continue with an appropriate follow-up. Further studies are needed to better understand this frequent complication.

Case Report: Diverse phenotypes of congenital poikiloderma associated with FAM111B mutations in codon 628: A case report and literature review

Congenital poikiloderma is an extremely rare autosomal dominant genetic syndrome, characterized by a combination of early onset poikiloderma, telangiectasia, and epidermal atrophy. FAM111B gene with multiple mutations has been identified as a potential causative gene for congenital poikiloderma. In this report, we described a boy with congenital poikiloderma confirmed by clinical manifestations. Next-generation sequencing based on a gene probe panel consisting of 541 genetic loci of genodermatoses, was used to screen mutations of the proband and his parents. Results showed that a missense mutation in the FAM111B gene c.1883G>A (rs587777238) was identified in the proband, but absent in his parents, indicating the mutation is de novo. In conclusion, a new case of congenital poikiloderma in China was reported, and the hotspot mutations in codon 628 of FAM111B gene was reviewed, as well as authenticating the uncertain association between genotypes and phenotypes in this rare disease.

Proposed Cellular Function of the Human FAM111B Protein and Dysregulation in Fibrosis and Cancer

FAM111B gene mutations are associated with a hereditary fibrosing poikiloderma known to cause poikiloderma, tendon contracture, myopathy, and pulmonary fibrosis (POIKTMP). In addition, the overexpression of FAM111B has been associated with cancer progression and poor prognosis. This review inferred the molecular function of this gene's protein product and mutational dysfunction in fibrosis and cancer based on recent findings from studies on this gene. In conclusion, FAM111B represents an uncharacterized protease involved in DNA repair, cell cycle regulation, and apoptosis. The dysregulation of this protein ultimately leads to fibrotic diseases like POIKTMP and cancers via the disruption of these cellular processes by the mutation of the FAM111B gene. Hence, it should be studied in the context of these diseases as a possible therapeutic target.

Mutations within the putative protease domain of the human FAM111B gene may predict disease severity and poor prognosis: A review of POIKTMP cases

Mutations in the human FAM111B gene are associated with a rare, hereditary multi‐systemic fibrosing disease, POIKTMP. To date, there are ten POIKTMP‐associated FAM111B gene mutations reported in thirty‐six patients from five families globally. To investigate the clinical significance of these mutations, we summarized individual cases by clinical features and position of the reported FAM111B gene mutations as those within and outside the putative protease domain (MWPPD and MOPPD respectively). MWPPD cases had more clinical manifestations than MOPPD (25 versus 18). Although the most common clinical features of poikiloderma, alopecia and hypohidrosis overall occurred in 94%, 86% and 75% of all cases with no significant differences between the MOPPD and MWPPD group, less common features included life‐threatening (pulmonary fibrosis 47% vs. 13%; liver abnormalities specifically cirrhosis 26% vs. 7%) and physically disabling conditions (myopathy 53% vs. 20%; tendon contracture 55% vs. 7%) were more common in MWPPD cases. Similarly, the only 2 cases of POIKTMP with fatal pancreatic cancers were both only in the MWPPD group. This review thus suggests that mutations within the putative protease domain of the FAM111B protein are associated with a broader range of clinical features and may predict increased POIKTMP severity and a poorer prognosis.

Spontaneous chromosomal instability in peripheral blood lymphocytes from two molecularly confirmed Italian patients with Hereditary Fibrosis Poikiloderma: insights into cancer predisposition

Two Italian patients with the initial clinical diagnosis of Rothmund-Thomson syndrome were negative for RECQL4 mutations but showed in peripheral blood cells a spontaneous chromosomal instability significantly higher than controls. Revisiting after time their clinical phenotype, the suggestive matching with the autosomal dominant syndrome Poikiloderma, Hereditary Fibrosing with Tendon Contracture, Myopathy and Pulmonary fibrosis (POIKTMP) was confirmed by identification of the c.1879A>G (p.Arg627Gly) alteration in FAM111B. We compare the overall clinical signs of our patients with those of reported carriers of the same mutation and present the up-to-date mutational repertoire of FAM111B and the related phenotypic spectrum. Our snapshot highlights the age-dependent clinical expressivity of POIKTMP and the need to follow-up patients to monitor the multi-tissue impairment caused by FAM111B alterations. We link our chromosomal instability data to the role of FAM111B in cancer predisposition, pointed out by its implication in DNA-repair pathways and the outcome of pancreatic cancer in 2 out of 17 adult POIKTMP patients. The chromosomal instability herein highlighted well connects POIKTMP to cancer-predisposing syndromes, such as Rothmund-Thomson which represents the first hereditary poikiloderma entering in differential diagnosis with POIKTMP.

Inherited skin disorders presenting with poikiloderma

Poikiloderma is a skin condition that combines atrophy, telangiectasia, and macular pigment changes (hypo- as well as hyperpigmentation). It is often mistaken for mottled pigmentation by general practitioners or nondermatology specialists. Poikiloderma can be a key presenting symptom of Rothmund-Thomson syndrome (RTS), dyskeratosis congenita (DC), hereditary sclerosing poikiloderma (HSP), hereditary fibrosing poikiloderma with tendon contractures, myopathy, and pulmonary fibrosis (POIKTMP), xeroderma pigmentosum (XP), Bloom syndrome (BS), Kindler syndrome (KS), and Clericuzio-type poikiloderma with neutropenia (PN). In these conditions, poikiloderma starts early in life, usually before the second or third year. They may also be associated with photosensitivity and other significant multi-organ manifestation developed later in life. Poikiloderma could indicate the presence of a genetic disorder with potentially serious consequences. Poikiloderma almost always precedes more severe manifestations of these genodermatoses. Prompt diagnosis at the time of presentation could help to prevent complications and mitigate the course of the disease. This review discusses these to help the practicing clinician manage patients presenting with the symptom. To further facilitate early recognition, this paper also proposes a simple diagnostic algorithm.

Determination of genetic aberrations and novel transcripts involved in the pathogenesis of oligodendroglioma using array comparative genomic hybridization and next generation sequencing

The aim of the present study was to determine the genetic aberrations and novel transcripts, particularly the fusion transcripts, involved in the pathogenesis of low-grade and anaplastic oligodendroglioma. In the present study, tissue samples were obtained from patients with oligodendroglioma and additionally from archived tissue samples from the Brain Tumor Tissue Bank of the Brain Tumor Foundation of Canada. Six samples were obtained, three of which were low-grade oligodendroglioma and the other three anaplastic oligodendroglioma. DNA and RNA were extracted from each tissue sample. The resulting genomic DNA was then hybridized using the Agilent CytoSure 4×180K oligonucleotide array. Human reference DNA and samples were labeled using Cy3 cytidine 5′-triphosphate (CTP) and Cy5 CTP, respectively, while human Cot-1 DNA was used to reduce non-specific binding. Microarray-based comparative genomic hybridization data was then analyzed for genetic aberrations using the Agilent Cytosure Interpret software v3.4.2. The total RNA isolated from each sample was mixed with oligo dT magnetic beads to enrich for poly(A) mRNA. cDNAs were then synthesized and subjected to end-repair, poly(A) addition and connected using sequencing adapters using the Illumina TruSeq RNA Sample Preparation kit. The fragments were then purified and selected as templates for polymerase chain reaction amplification. The final library was constructed with fragments between 350–450 base pairs and sequenced using deep transcriptome sequencing on an Illumina HiSeq 2500 sequencer. The array comparative genomic hybridization revealed numerous amplifications and deletions on several chromosomes in all samples. However, the most interesting result was from the next generation sequencing, where one anaplastic oligodendroglioma sample was demonstrated to have five novel fusion genes that may potentially serve a critical role in tumor pathogenesis and progression.

[Pulmonary fibrosis associated with hereditary fibrosing poikiloderma caused by FAM111B mutation: A case report]

INTRODUCTION

Hereditary fibrosing poikiloderma with tendon contractures, myopathy and pulmonary fibrosis (POIKTMP) is a recently described, extremely rare, entity belonging to the spectrum of inherited poikilodermas. It is provoked by a mutation of the FAM111B gene. Respiratory involvement has never been fully described but usually involves a restrictive respiratory pattern. We present here a case of pulmonary fibrosis associated with POIKTMP and describe the clinical, functional, radiological and evolutionary characteristics.

OBSERVATION

A 38 year-old patient with poikiloderma diagnosed in childhood was referred on account of dyspnoea. Initial evaluation showed a diffuse, fibrosing, interstitial pneumonitis with upper lobe predominance, associated with severe muscular involvement on imaging that remained sub-clinical during the evolution of the disease. Lung function impairment was severe and a rapid worsening of the pulmonary fibrosis and an acute exacerbation led to death after a follow-up of 21 months.

CONCLUSION

This case illustrates the fibrosing pulmonary involvement associated with POIKTMP and confirms its extreme severity. It is found only in adults and is universally fatal after a variable time. It highlights the necessity for a systematic screening as soon as the diagnosis of POIKTMP is confirmed in order to establish specialised respiratory management.