Voice Pitch Shaping and Genderization: New Needs of Cosmetic Phonoplastic Surgery.

Voices can convey content, emotion, and essential information about an individual's gender and social information. Closely related to gender identification and sexual attraction, voices also positively affect many psychological factors of individuals. Surgeries have evolved from treating congenital diseases to fulfilling an individual's aesthetic needs for voice. Voice shaping is emerging as the next cosmetic surgery hotspot after skincare and appearance and body shaping. This paper summarizes the development of voice pitch shaping and genderization procedures out of the cosmetic need. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based medicine ratings, please refer to the Table of Contents or the online Instructions to Authors https://www.springer.com/00266 .

Age-dependent copy number variations of TP53 tumour suppressor gene associated with altered phosphorylation status of p53 protein in sporadic schwannomas.

PURPOSE: Point mutations of TP53 tumour suppressor are very rare in schwannomas. We aim to characterize the frequency of exonic copy-number changes of the gene in the tumour and to examine the association between TP53 alterations, phosphorylation status of p53 protein and clinical phenotypes. METHODS: The alterations of TP53 were screened by a combination of Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA) in a total of 44 vestibular schwannomas. The mutation index (MI) in a tumour was defined as the number of exons mutated/ the number of exons tested. Phosphorylation status of p53 protein was investigated by immunoblotting and immunofluorescence. RESULTS: MLPA analysis showed single and multi-exon deletion mutations of TP53 in 65.7% of the cases. Comparisons of clinical features between mutated and non-mutated patients established an association of TP53 mutations with progressive phenotypes, including an earlier formation and a larger tumour. In addition, there were significant correlations between MI and both patients' age and tumour size. The Ser 392 phosphorylation level of p53 varied among tumours, and correlation analysis revealed an age-dependent phosphorylation pattern. The majority of tumours with hyperphosphorylated p53 were from mutated and young patients, suggesting an association of Ser392 phosphorylation with the mutational status of TP53 involved in the acceleration of tumour growth in young individuals. Moreover, Ser 392 phosphorylation contributed to a nuclear accumulation of p53 in schwannona cultures with TP53 mutation. CONCLUSIONS: An interplay between the mutation status of TP53, phosphorylation patterns and tumour behaviors might be established in the disease.

A Novel Missense Mutation of NOG Interferes With the Dimerization of NOG and Causes Proximal Symphalangism Syndrome in a Chinese Family.

OBJECTIVES: NOG is an antagonist to bone morphogenetic proteins and plays an important role in proper bone and joint development. Dominant mutations in NOG may lead to a series of symphalangism spectrum disorders. In this study, we aimed to identify the genetic cause and the pathogenic mechanism of an autosomal dominant disorder with cosegregating proximal symphalangism and conductive hearing impairment in a Chinese family. METHODS: Mutation screening of NOG was performed in the affected family members by polymerase chain reaction (PCR) amplification and direct sequencing. Western blotting analysis of NOG was performed in the leukocyte samples of the family members. RESULTS: A novel p.W150C heterozygous mutation in NOG was identified cosegregating with the proximal symphalangism disorder in the family. Western blotting analysis showed that the p.W150C mutation interferes with the dimerization of the mutant NOG. CONCLUSIONS: Our results agreed with previously published results of in vitro studies and suggested that impaired dimerization of mutant NOG is an important pathogenic mechanism for the NOG-related symphalangism spectrum disorder.

Facial and lower cranial nerve function preservation in lateral approach for craniocervical schwannomas.

The purpose of this study was to discuss surgical approach selection, surgical procedures, and treatment strategy for preservation of the facial and lower cranial nerve function in craniocervical schwannomas surgery. Between 2002 and 2011, 44 craniocervical schwannomas were operated in Xinhua hospital of Shanghai, China by the same surgical team. The records were reviewed retrospectively regarding clinical presentation, radiographic assessment, surgical approaches selection, surgical procedures and facial and lower cranial nerve follow-up outcomes. Headache or neck pain was present in 30 patients (68.2 %) and cervical mass in 9 patients (20.5 %). Cranial nerve impairments, mainly involving the vagus nerve, were present in 19 patients (43.2 %) and hypoglossal nerve in five patients (11.4 %). 22 tumors were intra- and extracranial, 10 were intra-cranial and 12 were extra-cranial. According to the tumor region, infratemporal fossa type A approach, petrous occipital transsigmoid approach and transcervial approach were selected for tumor removal. Gross-total resection was achieved in 40 patients (90.9 %). Adjunctive radiosurgery was used in the management of residual tumor in two patients; tumor control was ultimately obtained in all cases. During follow-up period, good facial function was obtained in 42 patients (95.5 %) and complete compensation of lower cranial nerve function was achieved in all patients. The preoperative estimation of tumor in nature is of great importance in the determination of proper surgical planning of craniaocervical schwannomas. Facial nerve and lower cranial nerve function can be preserved in maximal degree by proper surgical approaches and careful operative manipulation. Initial surgical resection followed by radiosurgery may be an effective option for some special patients.

The role of NF2 gene mutations and pathogenesis-related proteins in sporadic vestibular schwannomas in young individuals.

Vestibular schwannomas (VSs) are benign tumors arising from eighth cranial nerve and most often occur sporadically in individuals of middle age group. Sporadic VSs are rarely reported in the young population. In this study, we evaluated clinical behaviors of 12 young sporadic VSs by the statistical comparison with a matched series of 145 adult cases. We found that young tumors were characterized by an earlier onset of initial symptom, shorter duration from the first symptom to diagnosis, and larger tumor size than adult ones. Standard sequencing demonstrated the presence of NF2 mutations in eight tumors. All NF2 mutations identified were truncating mutations (nonsense, frameshift, and splicing-site mutations). Earlier formation of VSs in young patients was evidenced by the high incidence of NF2 mutations (66.7%) far beyond our previous study in the adult case series (34.5%). Furthermore, young tumors exhibited deficient merlin or heightened phosphorylated merlin that was subsequently demonstrated to be well correlated with increased tumor size. Finally, we compared protein levels of four pathogenesis-related molecules between young and adult group but there was no significant difference. These results led us to suggest that high frequency of NF2 mutations may play a critical role in early tumorigenesis of young VSs. Moreover, merlin deficiency or phosphorylation status of merlin was involved in their earlier development. Further study remains to fully understand the mechanism for the rapid growth of young VSs.

GEF-H1/RhoA signaling pathway mediates pro-inflammatory effects of NF-κB on CD40L-induced pulmonary endothelial cells.

One of the key targets of the inflammatory response in acute lung injury (ALI) is the human pulmonary micro-vascular endothelial cells (HPMVECs). Owing to its role in the activation of endothelial cells (ECs), CD40L figures prominently in the pathogenesis of ALI. Increasing evidences have showed that CD40L mediates inflammatory effects on ECs, at least in part, by triggering NF-κB-dependent gene expression. However, the mechanisms of such signal transmission remain unknown. In this study, we found that CD40L stimulated the transactivation of NF-κB and expression of its downstream cytokines in a p38 MAPK-dependent mechanism in HPMVECs. In addition, CD40L-mediated inflammatory effects might be correlated with the activation of the IKK/IκB/NF-κB pathway and nuclear translocation of NF-κB, being accompanied by dynamic cytoskeletal changes. GEF-H1/RhoA signaling is best known for its role in regulating cytoskeletal rearrangements. An interesting finding was that CD40L induced the activation of p38 and IKK/IκB, and the subsequent transactivation of NF-κB via GEF-H1/RhoA signaling. The critical role of GEF-H1/RhoA in CD40L-induced inflammatory responses in the lung was further confirmed in GEF-H1 and RhoA knockout mouse models, both of which were established by adeno-associated virus (AAV)-mediated delivery of sgRNAs into mice with EC-specific Cas9 expression. These results taken together suggested that p38 and IKK/IκB-mediated signaling pathways, both of which lied downstream of GEF-H1/RhoA, may coordinately regulate the transactivation of NF-κB in CD40L-activated HPMVECs. These findings may help to determine key pharmacological targets of intervention for CD40L-activated inflammatory effects associated with ALI.

Impact of inner ear malformation and cochlear nerve deficiency on the development of auditory-language network in children with profound sensorineural hearing loss.

Profound congenital sensorineural hearing loss (SNHL) prevents children from developing spoken language. Cochlear implantation and auditory brainstem implantation can provide partial hearing sensation, but language development outcomes can vary, particularly for patients with inner ear malformations and/or cochlear nerve deficiency (IEM&CND). Currently, the peripheral auditory structure is evaluated through visual inspection of clinical imaging, but this method is insufficient for surgical planning and prognosis. The central auditory pathway is also challenging to examine in vivo due to its delicate subcortical structures. Previous attempts to locate subcortical auditory nuclei using fMRI responses to sounds are not applicable to patients with profound hearing loss as no auditory brainstem responses can be detected in these individuals, making it impossible to capture corresponding blood oxygen signals in fMRI. In this study, we developed a new pipeline for mapping the auditory pathway using structural and diffusional MRI. We used a fixel-based approach to investigate the structural development of the auditory-language network for profound SNHL children with normal peripheral structure and those with IEM&CND under 6 years old. Our findings indicate that the language pathway is more sensitive to peripheral auditory condition than the central auditory pathway, highlighting the importance of early intervention for profound SNHL children to provide timely speech inputs. We also propose a comprehensive pre-surgical evaluation extending from the cochlea to the auditory-language network, showing significant correlations between age, gender, Cn.VIII median contrast value, and the language network with post-implant qualitative outcomes.

Origins of biallelic inactivation of NF2 in neurofibromatosis type 2.

BACKGROUND: Elucidating the mechanism by which biallelic inactivation evolved could provide a mechanistic understanding for NF2 tumorigenesis and also a rationale for clinical management. METHODS: A cohort of 60 NF2 patients was recruited. Next-generation sequencing of tumor and paired control samples was used to explore how NF2 mutations evolve in determining the clinical phenotypes. RESULTS: In total, 60 blood samples (one from each patient) and 61 (from 35 patients) NF2-associated tumors were collected. Next-generation sequencing of the blood samples detected "first hit" NF2 mutation in 35/60 donors (58.3%), 82.9% of which (29/35) bear heterozygous germline mutations, and 17.1% (6/35) of which are mosaics with variable allelic frequency (VAF). While a number of NF2 patients were found without germline mutation, most (57/61, 93.4%) NF2-associated tumors were identified with NF2 somatic mutation. We calculated the correlation between the onset latency of mosaic and germline NF2 allele carriers with the mosaicism VAF. The mosaicism VAF is negatively and linearly correlated to clinical symptom onset latency (R2 = 0.3677, P = .00351), suggesting biallelic inactivation probability is a linear function of "first hit" prevalence in the body. The second NF2 somatic mutation occurrence time positively correlates with the onset of clinical symptoms (R2 = 0.4151, P = .02633), suggesting tumor growth is linearly proportional to the time after biallelic inactivation. CONCLUSIONS: Our results suggested that biallelic inactivation of NF2 evolved through neutral drift and preexisting first hit NF2 allele determines certain aspects of the clinical symptoms. Genetic diagnosis should be included in the diagnostic criteria and treatment consideration of NF2.

Characterization of a newly established schwannoma cell line from a sporadic vestibular schwannoma patient.

A stable, human sporadic vestibular schwannoma cell line is not currently available. By using a lentivirus-mediated transfection from a 41-year-old sporadic vestibular schwannoma patient, primary schwannoma cells were obtained, cultured and immortalized using the hHERT gene. The NF2 gene of the resulting JEI-001 cell line contains a specific Exon 5 mutation. The schwannoma cell origin of this cell line was confirmed using STR techniques and immunocytochemistry. A comparison between the primary tumor tissue and JEI-001 revealed a common mutation of the NF2 gene, which indicated that the JEI-001 cell line had retained most of its original tumor characteristics. The JEI-001 cell line was found to be non-tumorigenic in nude mice, but certain growth features had been altered, resulting in changes such as independence from the Schwann cell growth factors and a higher proliferation rate. This was the first known study to establish cell lines immortalized from human sporadic vestibular schwannoma that had different characteristics from that of HEI-193. This is a novel model system that can be used for the study of NF2 gene functions, in order to elaborate on the biological features of sporadic vestibular schwannoma, even including familial NF2 tumors, and to further explore the molecular pathogenesis and develop new adjuvant therapies.

High throughput proteomic and metabolic profiling identified target correction of metabolic abnormalities as a novel therapeutic approach in head and neck paraganglioma.

Head and neck paragangliomas (HNPGLs) are rare neoplasms that represent difficult treatment paradigms in neurotology. Germline mutations in genes encoding succinate dehydrogenase (SDH) are the cause of nearly all familial HNPGLs. However, the molecular mechanisms underlying tumorigenesis remain unclear. Mutational analysis identified 6 out of 14 HNPGLs harboring clinicopathologic SDH gene mutations. The SDHB gene was most frequently mutated in these patients, and western blot showed loss of SDHB protein in tumors with SDHB mutations. The paraganglioma cell line (PGL-626) was established from a sample that harbored a missense SDHB mutation (c.649C > T). Spectrometric analysis using tandem mass tags identified 151 proteins significantly differentially expressed in HNPGLs compared with normal nerves. Bioinformatics analyses confirmed the high level of enrichment of oxidative phosphorylation and metabolism pathways in HNPGLs. The mitochondrial complex subunits NDUFA2, NDUFA10, and NDUFA4, showed the most significantly increased expression and were localized predominantly in the cytoplasm of PGL-626 cells. The mitochondrial complex I inhibitor metformin exerted dose-dependent inhibitory effects on PGL-626 cells via cooperative down-regulation of NDUFA2, 4, and 10, with a significant decrease in the levels of reactive oxygen species and mitochondrial membrane potential. Further metabolomic analysis of PGL-626 cells showed that metabolites involved in central carbon metabolism in cancer and sphingolipid signaling pathways, pantothenate and CoA biosynthesis, and tryptophan and carbon metabolism were significantly altered after metformin treatment. Thus, this study provides insights into the molecular mechanisms underlying HNPGL tumorigenesis and identifies target correction of metabolic abnormalities as a novel therapeutic approach for this disease.

Proteomic screening identifies PML/p53 axis as a potential treatment target of facial nerve schwannomas.

Facial nerve schwannomas (FNS) represents one of the more difficult treatment paradigms in neurotology. The aim of this study is to investigate the molecular alterations of FNS, thus providing potential targets treatable in the tumour. We for the first time suggest that the deficiency of merlin (the product of NF2 tumour suppressor) is probably one of the key mechanisms underlying FNS tumourigenesis, although no disease-causing NF2 mutations were demonstrated in tumour samples. TMT-labeled spectrometry analysis was used to identify the proteome of FNS relative to nerve controls. Eighty-four significantly deregulated proteins were identified, among which the PML tumour suppressor showed the most significantly increased expression. The PML protein was distributed in the nucleoplasm of non-tumorous Schwann cells, whereas it was preferentially confined to the cytoplasm of FNS cultures. Overexpression of PML and p53, partner proteins positively regulating each other to trigger apoptosis, was further confirmed in FNS tissues/cultures, and this correlated with a significant decrease in the proliferation of FNS cultures in comparison to Schwann cells. It is therefore probable that PML-p53 overexpression may occur as part of protective cellular mechanisms in response to the proliferation signal mediated by loss of merlin in FNS, in accordance with the fact that the tumour is benign slow-growing. This hypothesis was supported by the finding that the p53 activator nutlin-3 could exert dose-dependent inhibitory effects on FNS cultures via a cooperative induction of PML-p53 levels. Thus, the current study may present a potential treatment target directed on the molecular mechanisms of this disease.

Degradable and Bioadhesive Alginate-Based Composites: An Effective Hemostatic Agent.

The perfect hemostatic material should be capable of rapidly controlling substantial hemorrhaging from visceral organs, veins, and arteries. Ideally, it should be biodegradable, biocompatible, easily applied, and inexpensive. Herein, taking advantages of sodium alginate (SA), carboxymethyl chitosan (CMC), and collagen, a degradable powdery hemostatic composite (SACC) was synthesized using emulsification and cross-linking technology. The morphology and structure of SACC were determined using Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). This hemostatic material exhibited a typical generic sphere shape with narrow size distribution, rough surface, and satisfactory water absorption. Using in vitro bleeding and in vivo bleeding models (rat liver injury model and rat tail amputation model), it was shown that SACC had superior hemostatic actions compared to CMC and SA. Excellent cytocompatibility was proven during cytotoxicity tests and SEM observations. Histomorphological evaluation during the wound healing process proved the superior biocompatibility of SACC in a rat liver injury model. Biodegradability of SACC was demonstrated by immunofluorescence techniques both in vitro and in vivo. In summary, we have demonstrated the enormous potential of SACC, which has excellent hemostatic activity, biodegradability, and biocompatibility properties for use in clinical hemostasis applications.

Synergistic effect of Nutlin-3 combined with MG-132 on schwannoma cells through restoration of merlin and p53 tumour suppressors.

BACKGROUND: The great majority of sporadic vestibular schwannomas (VSs) are due to the mutations of the NF2 gene encoding merlin. Sporadic VSs exhibit variable growth patterns and only a small fraction of the tumours are fast-growing; however, the underlying mechanisms remain undefined. METHODS: DNA sequencing and dosage analysis were used to identify the NF2 mutation status in sporadic schwannomas. The expression and sub-cellular localization of merlin and p53-MDM2 were assessed by immunoblotting, qRT-PCR and immunofluorescence. In vitro and in vivo studies were performed to reveal the effects of Nutlin-3 (a MDM2 inhibitor) and/or MG-132(a proteasome inhibitor) on schwannomas. The proliferation of schwannoma cells was assessed by CCK-8 assay, EdU staining and Flow cytometry analysis. FINDINGS: Double genetic hits of NF2 tended to occur in fast-growing tumours, characterized by the absence of merlin. The deregulation of p53-MDM2 was demonstrated to mediate merlin-deficient tumour growth, characterized by a nuclear accumulation of stabilized MDM2, contributing to a nuclear export of p53 for degradation. Nutlin-3 blocked the proliferation of schwannoma cells via a cooperative recovery of merlin and p53, accompanied by the shuttling of both proteins from the cytoplasm to the nucleus. We further demonstrated a difference in the sensitivity to Nutlin-3 between schwannoma cells with and without merlin expression. Nutlin-3 combined with MG-132 narrowed this between-group difference and triggered stronger inhibitory effects on the growth of schwannomas through coordinated reactivation of p53. INTERPRETATION: These findings present treatment strategies directed on the pathogenesis of sporadic schwannomas. FUND: National Natural Science Foundation of China.

Long-Term Hearing Preservation Outcomes for Small Vestibular Schwannomas: Retrosigmoid Removal Versus Observation.

OBJECTIVE: Management of small vestibular schwannomas (VSs) consists of three options: serial observation, radiosurgery, and microsurgery. The authors reported the long-term hearing outcomes after retrosigmoid tumor removal in 110 patients and hearing follow-up outcomes in 160 serial observation patients with small VSs to explore the appropriate management strategy and predictive factors of hearing preservation for small VSs. STUDY DESIGN: Retrospective study. SETTING: Tertiary referral center. PATIENTS: In this study, 110 patients with small VS (purely intracanalicular/cerebellopontine angle tumor ≤15 mm) during a 15-year period, from January 2001 to December 2015, were candidates for hearing preservation surgery through retrosigmoid approach, while 160 patients were candidates for serial observation. The main outcome measure was preservation of hearing under different hearing levels, assessed with the classification of American Academy of Otolaryngology-Head and Neck Surgery. RESULTS: Preoperative hearing levels of the 110 study patients were Class A in 49 patients, Class B in 43 patients, and Class C in 18 patients. In all surgery patients (n = 110), 97.3% (107/110) patients maintained the same level during postoperative follow-up (mean follow-up time was 49.1 ±â€Š28.2 mo) and 86 (78.2%) had complete radiologic and audiometric data at least 4 years follow-up for review. In the 4 years follow-up surgery group (n = 86), postoperative hearing levels were Class A, B, C, and D for 22, 11, 18, and 35 patients, and postoperative rates of preservation of serviceable and useful hearing were 59.3% (51/86) and 47.1% (33/70), respectively. In serial observation group, mean follow-up time was 35.2 ±â€Š33.1 months; mean tumor size at presentation was 8.6 ±â€Š4.3 mm; overall mean tumor growth rate was 1.08 ±â€Š2.3 mm/yr; serviceable hearing preservation rate of 98 patients was 54.1% (53/98) at the 5-year end point and 48.7% (37/76) at the 7-year end point. CONCLUSION: Tumor removal should be the first treatment option for patients with small VSs and preserved hearing, especially for young patients with good hearing; retrosigmoid approach is an effective and safe approach for small VSs removal with excellent functional outcomes; better preoperative hearing predicted a higher rate of postoperative hearing preservation; patients without fundal extension were more likely to achieve hearing preservation than those with fundal extension, but no difference had been detected when retrosigmoid removal assisted with endoscope was performed; patients with small tumors originating from SVN were more likely to achieve hearing preservation compared with those with IVN-originating tumors.

Genetic and epigenetic patterns in patients with the head-and-neck paragangliomas associate with differential clinical characteristics.

PURPOSE: In addition to genetic alterations, the importance of a CpG island methylator phenotype, characterized by methylation of multiple tumour-suppressor genes (TSGs), has been acknowledged in many cancer types. This study was done to determine the impact of genetic and epigenetic patterns on the clinical characteristics of the head and neck paragangliomas (HNPGLs). METHODS: The retrospective study examined a series of 37 patients with HNPGLs who underwent surgical resection between 2010 and 2015. The mutations in the succinate dehydrogenase (SDH) genes were detected using direct DNA sequencing. Aberrant hypermethylation of the CpG islands of a panel of ten TSGs was also analysed using methylation-specific PCR. RESULTS: Direct sequencing demonstrated the presence of germline SDH mutations in ten HNPGLs. Comparisons of clinical features between mutated and non-mutated HNPGLs established an association of SDH mutations with progressive phenotypes, including an earlier formation, multiple lesions, or malignancy. There was also a significant correlation between the presence of SDH mutations and the number of TSGs methylated in HNPGLs. The SDH-related tumours were therefore more likely to suffer from a CpG island methylator phenotype. Four differentially methylated TSGs in mutated tumours vs non-mutated counterparts were identified with inefficient expression through Real-Time PCR analysis. CONCLUSIONS: Our results suggested that epigenetic inactivation on multiple TSGs may serve as a key mechanism for the progressive behaviors of SDH-mutated HNPGLs. Thus, an interplay between genetic status, epigenetic alterations, and clinical features might be established in the disease.

Differential NF2 Gene Status in Sporadic Vestibular Schwannomas and its Prognostic Impact on Tumour Growth Patterns.

The great majority of sporadic vestibular schwannomas (VSs) are due to the inactivation of the NF2 gene. In this study, we found age-dependent differences in the clinical parameters of sporadic VSs. Young patients were characterized by progressive tumour behaviours, including earlier onset of initial symptoms, shorter symptom duration and larger tumour size. An increased rate of "two-hits" of both NF2 alleles, usually by mutation and allelic loss, was observed in young cases compared to older, and this correlated with the loss of protein and mRNA expression. In contrast, the tumours with a single mutation (referred to as 'one-hit') exhibited obvious expression levels. Moreover, a mixture of merlin-expressing tumour cells and non-expressing tumour cells was observed in 'one-hit' schwannomas, suggesting that a subset of 'one-hit' tumour cells was present in these tumours. To mimic the growth promoting effects by the second hit, we performed lentivirus-mediated NF2 knockdown in the 'one-hit' schwannoma cultures. Following the loss of NF2 expression, schwannoma cultures demonstrated increased proliferation rates. Above all, we have identified a correlation between the NF2 status and the growth patterns of sporadic VSs. The treatment decision-making, microsurgery or "wait and scan" strategy, should be carried out according to the tumour's genetic background.

p53 performs an essential role in mediating the oncogenic stimulus triggered by loss of expression of neurofibromatosis type 2 during in vitro tumor progression.

The loss of the tumor suppressor neurofibromatosis type 2 gene, encoding merlin, has been considered to be a fundamental event during the malignant progression of various cell types. However, a consensus for the mainstream mechanism, by which merlin deficiency contributes to uncontrolled cellular proliferation, has not been reached. The present study aimed to determine whether silencing of merlin using lentivirus-based short hairpin RNA potentiates cellular proliferation and cell cycle progression in human colon carcinoma HCT116 cell lines, expressing p53. The present results demonstrated that merlin knockdown contributed to cellular proliferation and G1/S cell cycle progression to a greater extent in HCT116 cells wide-type for p53 (p53wt) compared with p53-null (p53-/-) cells. This was supported by overexpression experiments which demonstrated a significant inhibitory effect of excess merlin on cellular proliferation only in HCT116 p53wt cells. In order to investigate the underlying mechanisms of action, the expression of p53-involved G1/S transition genes was evaluated by western blot analysis. For HCT116 p53wt cells, merlin loss suppressed p53 expression, and therefore the dysregulation of cell cycle regulatory proteins, including p21, cyclin D1/cyclin-dependent kinase (CDK)4 and cyclin E1/CDK2 complexes. However, merlin knockdowns had no impact on the expression of any of the aforementioned molecules in p53-/- cells, indicating that lack of merlin resulted in G1/S cell cycle progression, and thereby uncontrolled cellular proliferation mainly via the regulation of p53-mediated pathways. Taken together, it was proposed that p53 performs an essential role in mediating the oncogenic stimulus triggered by merlin loss, and p53 is a molecule that should be investigated for its potential in targeted drug therapy for merlin-deficient malignancies.