The molecular mechanisms that underlie the tumor suppressor function of LKB1

A Comparative Genomic Analysis of Parathyroid Adenomas and Carcinomas Harboring Heterozygous Germline CDC73 Mutations

CONTEXT

Parathyroid cancer has been linked to germline mutations of the Cell Division Cycle 73 (CDC73) gene. However, carriers harboring cancer-associated germline CDC73 mutations may develop only parathyroid adenoma or no parathyroid disease. This incomplete penetrance indicates that additional genomic events are required for parathyroid tumorigenesis.

OBJECTIVE

(1) Determine the status of the second CDC73 allele in parathyroid tumors harboring germline CDC73 mutations and (2) compare the genomic landscapes between parathyroid carcinomas and adenomas.

DESIGN

Whole-exome and RNA sequencing of 12 parathyroid tumors harboring germline CDC73 mutations (6 adenomas and 6 carcinomas) and their matched normal tissues.

RESULTS

All 12 parathyroid tumors had gained 1 somatic event predicted to cause a complete inactivation of the second CDC73 allele. Several distinctive genomic features were identified in parathyroid carcinomas compared to adenomas, including more single nucleotide variants bearing the C > G transversion and APOBEC deamination signatures, frequent mutations of the genes involved in the PI-3K/mTOR signaling, a greater number of copy number variations, and substantially more genes with altered expression. Parathyroid carcinomas also share some genomic features with adenomas. For instance, both have recurrent somatic mutations and copy number loss that impact the genes involved in T-cell receptor signaling and tumor antigen presentation, suggesting a shared strategy to evade immune surveillance.

CONCLUSION

Biallelic inactivation of CDC73 is essential for parathyroid tumorigenesis in carriers harboring germline mutations of this gene. Despite sharing some genomic features with adenomas, parathyroid carcinomas have more distinctive alterations in the genome, some of which may be critical for cancer formation.

Matrix metalloproteinases as the critical regulators of cisplatin response and tumor cell invasion

Cisplatin (CDDP) as one of the most common first-line chemotherapy drugs plays a vital role in the treatment of a wide range of malignant tumors. Nevertheless, CDDP resistance is observed as a therapeutic challenge in a large number of cancer patients. Considering the CDDP side effects in normal tissues, predicting the CDDP response of cancer patients can significantly help to choose the appropriate therapeutic strategy. In this regard, investigating the molecular mechanisms involved in CDDP resistance can lead to the introduction of prognostic markers in cancer patients. Matrix metalloproteinases (MMPs) have critical roles in tissue remodeling and cell migration through extracellular matrix degradation. Therefore, defects in MMPs functions can be associated with tumor metastasis and chemo resistance. In the present review, we discussed the role of MMPs in CDDP response and tumor cell invasion. PubMed, Scopus, Google Scholar, and Web of Science were searched using "MMP", "cisplatin", and "cancer" keywords for data retrieval that was limited to Apr 20, 2024. It has been reported that MMPs can increase CDDP resistance in tumor cells as the effectors of PI3K/AKT, MAPK, and NF-κB signaling pathways or independently through the regulation of structural proteins, autophagy, and epithelial-to-mesenchymal transition (EMT) process. This review has an effective role in introducing MMPs as the prognostic markers and therapeutic targets in CDDP-resistant cancer patients.

STK11 Causative Variants and Copy Number Variations Identified in Thai Patients With Peutz-Jeghers Syndrome

Introduction Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant inherited disorder caused by germline mutations in the serine-threonine kinase 11 (STK11) tumor suppressor gene. This syndrome is characterized by hamartomatous gastrointestinal polyps, mucocutaneous melanin pigmentation, and a higher risk of developing various cancers. Methods We summarized the clinical and molecular characteristics of five unrelated Thai patients with PJS. Denaturing high-performance liquid chromatography (DHPLC) screening, coupled with direct DNA sequencing and multiplex ligation-dependent probe amplification (MLPA), were applied for the molecular analysis of STK11. Results A total of four STK11 pathogenic changeswere identified in the five PJS patients, including two frameshift variants (a novel c.199dup, p.Leu67ProfsTer96 and a known c.834_835del, p.Cys278TrpfsTer6) and two types of copy number variations (CNV), exon 1 deletion and exons 2-3 deletion. Among reported STK11 exonic deletions, exon 1 and exons 2-3 deletions were found to be the two most commonly deleted exons. Conclusion All identified STK11 mutations were null mutations that were associated with more severe PJS phenotypes and cancers. This study broadens the phenotypic and mutational spectrum of STK11 in PJS.

A novel missense mutation of the STK11 gene in a Chinese family with Peutz-Jeghers syndrome

BACKGROUND

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant inherited disease caused by mutations in the Serine-Threonine Kinase 11 (STK11) gene. This study aimed to diagnose a Chinese pedigree with PJS and to expand the spectrum of STK11 variants.

METHODS

We performed an inductive analysis of clinical features, gastrointestinal endoscopy, radiologic imaging, and pathological findings in a Chinese family with PJS. Whole-exome sequencing (WES), Sanger sequencing, and STK11 protein 3D structure prediction were performed for establishing a molecular diagnosis.

RESULTS

The proband, her mother, and grandfather presented with pigmentation spots on lips, oral mucosa, and fingers. Her mother and grandfather also had pigmentation spots on face and feet, while her brother had pigmentation spots only on the lower lip. On endoscopy, polyps were discovered in the proband, her mother, and grandfather. A novel heterozygous mutation (c.521A > C) in exon 4 of STK11 was identified in all four patients, leading to a change from histidine to proline in amino acid 174. The variable site p.H174 was highly conserved in different species on multiple sequence alignment analysis.

CONCLUSIONS

We diagnosed a Chinese pedigree with PJS based on clinical features, gastrointestinal endoscopy, and genetic testing results. Our results expanded the spectrum of STK11 variants, which will be helpful for genetic counseling.

Small Bowel Epithelial Precursor Lesions: A Focus on Molecular Alterations

The wider use of gastrointestinal endoscopic procedures has led to an increased detection of small intestinal preneoplastic and neoplastic epithelial lesions, most of which are identified in the duodenum and ampullary region. Like their malignant counterparts, small intestinal glandular precursor lesions, which include adenomas and hamartomas, may arise sporadically or be associated with hereditary tumor syndromes, such as familial adenomatous polyposis, MUTYH-associated polyposis, Lynch syndrome, Peutz-Jeghers syndrome, juvenile polyposis syndrome, and Cowden syndrome. In addition, dysplastic, preinvasive lesions have been observed adjacent to small bowel adenocarcinomas complicating immune-related disorders, such as celiac or Crohn’s disease. Adenomatous lesions may exhibit an intestinal-type, gastric-type, or, very rarely, serrated differentiation, related to different molecular pathogenetic mechanisms. Finally, in the background of multiple endocrine neoplasia 1 syndrome, precursor neuroendocrine growths have been described. In this review we offer a comprehensive description on the histo-molecular features of the main histotypes of small bowel epithelial precursors lesions, including: (i) sporadic adenomas (intestinal-type and gastric-type; non-ampullary and ampullary); (ii) syndromic adenomas; (iii) small bowel dysplasia in celiac and Crohn’s disease; (iv) serrated lesions; (v) hamartomatous lesions; and (vi) neuroendocrine precursor lesions.

Colon cancer of Peutz-Jeghers syndrome with gallolyticus endocarditis

We report a case of Peutz-Jeghers syndrome with gallolyticus endocarditis which has not yet been reported. Colon cancer was observed and implicated in Peutz-Jeghers syndrome. A 44-year-old female with fever and heart murmur was diagnosed as infective endocarditis caused by streptococcus gallolyticus. After treatment with antibiotics and mitral valbuloplasty, we performed gastrointestinal endoscopic studies and found polyps in stomach and colon. Histological findings of a large pedunculated colon polyp revealed hamartomatous polyp with a lesion of adenocarcinoma with adenoma. She had pigmentation of digits. Her father had also digits pigmentation and died of pancreas cancer. Peutz-Jeghers syndrome with colon cancer was incidentally diagnosed by infective endocarditis and subsequent colonoscopy.

LKB1/Mo25/STRAD uniquely impacts sarcomeric contractile function and posttranslational modification

The myocardium undergoes extensive metabolic and energetic remodeling during the progression of cardiac disease. Central to remodeling are changes in the adenine nucleotide pool. Fluctuations in these pools can activate AMP-activated protein kinase (AMPK), the central regulator of cellular energetics. Binding of AMP to AMPK not only allosterically activates AMPK but also promotes phosphorylation of AMPK by an upstream kinase complex, LKB1/Mo25/STRAD (liver kinase B 1, mouse protein 25, STE-related adaptor protein). AMPK phosphorylation by the LKB1 complex results in a substantial increase in AMPK activity. Molecular targeting by the LKB1 complex depends on subcellular localization and transcriptional expression. Yet, little is known about the ability of the LKB1 complex to modulate targeting of AMPK after activation. Accordingly, we hypothesized that differing stoichiometric ratios of LKB1 activator complex to AMPK would uniquely impact myofilament function. Demembranated rat cardiac trabeculae were incubated with varying ratios of the LKB1 complex to AMPK or the LKB1 complex alone. After incubation, we measured the Ca(2+) sensitivity of tension, rate constant for tension redevelopment, maximum tension generation, length-dependent activation, cooperativity, and sarcomeric protein phosphorylation status. We found that the Ca(2+) sensitivity of tension and cross-bridge dynamics were dependent on the LKB1 complex/AMPK ratio. We also found that the LKB1 complex desensitizes and suppresses myofilament function independently of AMPK. A phospho-proteomic analysis of myofilament proteins revealed site-specific changes in cardiac Troponin I (cTnI) phosphorylation, as well as a unique distribution of cTnI phosphospecies that were dependent on the LKB1 complex/ AMPK ratio. Fibers treated with the LKB1 complex alone did not alter cTnI phosphorylation or phosphospecies distribution. However, LKB1 complex treatment independent of AMPK increased phosphorylation of myosin-binding protein C. Therefore, we conclude that the LKB1/AMPK signaling axis is able to alter muscle function through multiple mechanisms.

Disease pattern in Danish patients with Peutz-Jeghers syndrome

PURPOSE

In this paper, we aimed to collect genetic and medical information on all Danish patients with Peutz-Jeghers syndrome (PJS), in order to contribute to the knowledge of phenotype and genotype. Peutz-Jeghers syndrome is a hereditary syndrome characterized by multiple hamartomatous polyps in the GI tract, mucocutaneous pigmentations, and an increased risk of cancer in the GI tract and at extraintestinal sites. Over 90 % of patients harbour a pathogenic mutation in STK11.

METHODS

Based on the Danish Pathology Data Bank, the Danish National Patient Register, as well as information from relevant departments at Danish hospitals, we identified patients and collected clinical and genetic information.

RESULTS

We identified 43 patients of which 14 were deceased. The prevalence was estimated to be ∼1 in 195,000 individuals. The median age at first symptom was 27.5 with invagination of the small bowel as the most frequent presenting symptom. We noted 18 occurrences of cancer at various anatomical sites, including a case of thyroid cancer and penile cancer. Eight of the deceased patients had died of cancer. Eighteen different mutations in STK11 had been detected in 28 patients.

CONCLUSION

This is the first comprehensive study of patients with Peutz-Jeghers syndrome in the Danish population identified from nationwide registers and databases. We have demonstrated that the expressivity of Peutz-Jeghers syndrome varies greatly among the patients, even within the same families, underlining the great phenotypic spectrum. Patients with PJS should be offered surveillance from childhood in order to prevent morbidity and reduce mortality.

A single-nucleotide polymorphism in serine-threonine kinase 11, the gene encoding liver kinase B1, is a risk factor for multiple sclerosis

We identified a family in which five siblings were diagnosed with multiple sclerosis (MS) or clinically isolated syndrome. Several women in the maternal lineage have comorbidities typically associated with Peutz Jeghers Syndrome, a rare autosomal-dominant disease caused by mutations in the serine-threonine-kinase 11 (STK11) gene, which encodes liver kinase B1. Sequence analysis of DNA from one sibling identified a single-nucleotide polymorphism (SNP) within STK11 intron 5. This SNP (dbSNP ID: rs9282860) was identified by TaqMan polymerase chain reaction (PCR) assays in DNA samples available from two other siblings. Further screening was carried out in samples from 654 relapsing-remitting MS patients, 100 primary progressive MS patients, and 661 controls. The STK11-SNP has increased frequency in all female patients versus controls (odds ratio = 1.66, 95% CI = 1.05, 2.64, p = .032). The STK11-SNP was not associated with disease duration or onset; however, it was significantly associated with reduced severity (assessed by MS severity scores), with the lowest scores in patients who also harbored the HLA-DRB1*1501 allele. In vitro studies showed that peripheral blood mononuclear cells from members of the family were more sensitive to the mitochondrial inhibitor metformin than cells from MS patients with the major STK11 allele. The increased association of SNP rs9282860 in women with MS defines this variant as a genetic risk factor. The lower disease severity observed in the context of HLA-DRB1*1501 combined with limited in vitro studies raises the provocative possibility that cells harboring the STK11-SNP could be targeted by drugs which increase metabolic stress.

Decreased expression and prognostic role of cytoplasmic BRSK1 in human breast carcinoma: correlation with Jab1 stability and PI3K/Akt pathway

OBJECTIVE

Jun activation domain-binding protein 1 (Jab1) was overexpressed in breast cancer, which was involved in degradation of the cyclin-dependent kinase inhibitor p27(Kip1). The objective of this study was to examine the effect of brain specific kinase 1 (BRSK1) expression on Jab1 over-expression and related signaling pathway in breast cancer.

METHODS

Immunohistochemical analysis was performed in 95 human breast carcinoma samples and the data were correlated with clinicopathologic features. Furthermore, Western blot analysis was performed for BRSK1 and Jab1 in breast carcinoma samples and cell lines to evaluate their protein levels and molecular interaction.

RESULTS

We found that the cytoplasmic BRSK1 expression was inversely associated with Jab1 expression (P<0.01) and correlated significantly with histologic grade (P=0.006), however nuclear BRSK1 expression couldn't obtain similar results. Kaplan-Meier analysis revealed that survival curves of low versus high expressers of cytoplasmic BRSK1 and Jab1 showed a highly significant separation in breast cancer (P<0.01). While in vitro, following release of breast cancer cell lines from serum starvation, the expression of Jab1, phosphor-Akt (p-Akt) was up-regulated, whereas BRSK1 and p27(Kip1) were decreased. Treatment of phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 could diminish Jab1 expression but increase BRSK1 expression. In addition, we employed siRNA technique to knock down Jab1 and/or BRSK1 expression and observed their effects on MDA-MB-231 cell growth.

CONCLUSIONS

BRSK1 is a novel tumor suppressor in breast cancer which inversely correlated with Jab1 expression, may involve in the restoring Jab1-induced suppression of p27(Kip1) and may regulate cell cycle through the PI3K/Akt pathway.

The transcriptional responsiveness of LKB1 to STAT-mediated signaling is differentially modulated by prolactin in human breast cancer cells

Background

Liver kinase 1 (LKB1) is an important multi-tasking protein linked with metabolic signaling, also controlling polarity and cytoskeletal rearrangements in diverse cell types including cancer cells. Prolactin (PRL) and Signal transducer and activator of transcription (STAT) proteins have been associated with breast cancer progression. The current investigation examines the effect of PRL and STAT-mediated signaling on the transcriptional regulation of LKB1 expression in human breast cancer cells.

Methods

MDA-MB-231, MCF-7, and T47D human breast cancer cells, and CHO-K1 cells transiently expressing the PRL receptor (long form), were treated with 100 ng/ml of PRL for 24 hours. A LKB1 promoter-luciferase construct and its truncations were used to assess transcriptional changes in response to specific siRNAs or inhibitors targeting Janus activated kinase 2 (JAK2), STAT3, and STAT5A. Real-time PCR and Western blotting were applied to quantify changes in mRNA and protein levels. Electrophoretic mobility shift (EMSA) and chromatin immunoprecipitation (ChIP) assays were used to examine STAT3 and STAT5A binding to the LKB1 promoter.

Results

Consistent with increases in mRNA, the LKB1 promoter was up-regulated by PRL in MDA-MB-231 cells, a response that was lost upon distal promoter truncation. A putative GAS element that could provide a STAT binding site mapped to this region, and its mutation decreased PRL-responsiveness. PRL-mediated increases in promoter activity required signaling through STAT3 and STAT5A, also involving JAK2. Both STATs imparted basally repressive effects in MDA-MB-231 cells. PRL increased in vivo binding of STAT3, and more definitively, STAT5A, to the LKB1 promoter region containing the GAS site. In T47D cells, PRL down-regulated LKB1 transcriptional activity, an effect that was reversed upon culture in phenol red-free media. Interleukin 6, a cytokine activating STAT signaling in diverse cell types, also increased LKB1 mRNA levels and promoter activity in MDA-MB-231 cells.

Conclusions

LKB1 is differentially regulated by PRL at the level of transcription in representative human breast cancer cells. Its promoter is targeted by STAT proteins, and the cellular estrogen receptor status may affect PRL-responsiveness. The hormonal and possibly cytokine-mediated control of LKB1 expression is particularly relevant in aggressive breast cancer cells, potentially promoting survival under energetically unfavorable conditions.

The role of AMP-activated protein kinase in quercetin-induced apoptosis of HL-60 cells

Our previous studies have shown that quercetin inhibits Cox-2 and Bcl-2 expressions, and induces human leukemia HL-60 cell apoptosis. In order to investigate the role of AMP-activated protein kinase (AMPK) on quercetin-induced apoptosis of HL-60 cells, we used flow cytometry to detect cell apoptosis. The expressions of LKB1, phosphorylated AMPK (p-AMPK), and Cox-2 protein were detected in HL-60 cells and normal peripheral blood mononuclear cells (PBMCs) by western blot. The expressions of LKB1, p-AMPK, and Cox-2 were detected in HL-60 cells after culture with quercetin. The expressions of p-AMPK were detected in HL-60 cells after culture with AMPK inhibitor Compound C. Then, the expressions of LKB1, p-AMPK, and Cox-2 were detected in HL-60 cells after culture with quercetin alone or quercetin + Compound C. It was found that there was no significant difference in LKB1 between PBMCs and HL-60. p-AMPK in PBMCs was higher than that in HL-60, while Cox-2 was lower. After culture of HL-60 with quercetin, p-AMPK was increased, Cox-2 was decreased, but LKB1 remained unchanged. After culture of HL-60 with Compound C, p-AMPK was decreased. There was no significant difference in LKB1 between the quercetin-alone and the quercetin + Compound C groups. p-AMPK decreased more significantly, while Cox-2 increased more significantly in the quercetin + Compound C groups than those in the quercetin-alone groups. Taken together, these findings suggested that quercetin activates AMPK expression in HL-60 cells independent of LKB1 activation, inhibits Cox-2 expression by activating AMPK, and further regulates the Bcl-2-dependent pathways of apoptosis to exert its anti-leukemia effect.

Liver kinase B1 expression promotes phosphatase activity and abrogation of receptor tyrosine kinase phosphorylation in human cancer cells

Aberrant receptor tyrosine kinase phosphorylation (pRTK) has been associated with diverse pathological conditions, including human neoplasms. In lung cancer, frequent liver kinase B1 (LKB1) mutations correlate with tumor progression, but potential links with pRTK remain unknown. Heightened and sustained receptor activation was demonstrated by LKB1-deficient A549 (lung) and HeLaS3 (cervical) cancer cell lines. Depletion (siRNA) of endogenous LKB1 expression in H1792 lung cancer cells also correlated with increased pRTK. However, ectopic LKB1 expression in A549 and HeLaS3 cell lines, as well as H1975 activating-EGF receptor mutant lung cancer cell resulted in dephosphorylation of several tumor-enhancing RTKs, including EGF receptor, ErbB2, hepatocyte growth factor receptor (c-Met), EphA2, rearranged during transfection (RET), and insulin-like growth factor I receptor. Receptor abrogation correlated with attenuation of phospho-Akt and increased apoptosis. Global phosphatase inhibition by orthovanadate or depletion of protein tyrosine phosphatases (PTPs) resulted in the recovery of receptor phosphorylation. Specifically, the activity of SHP-2, PTP-1β, and PTP-PEST was enhanced by LKB1-expressing cells. Our findings provide novel insight on how LKB1 loss of expression or function promotes aberrant RTK signaling and rapid growth of cancer cells.

Findings from the Peutz-Jeghers syndrome registry of uruguay

Background

Peutz-Jeghers syndrome (PJS) is characterized by intestinal polyposis, mucocutaneous pigmentation and an increased cancer risk, usually caused by mutations of the STK11 gene. This study collected epidemiological, clinical and genetic data from all Uruguayan PJS patients.

Methods

Clinical data were obtained from public and private medical centers and updated annually. Sequencing of the STK11 gene in one member of each family was performed.

Results and discussion

25 cases in 11 unrelated families were registered (15 males, 10 females). The average age of diagnosis and death was 18 and 41 years respectively. All patients had characteristic PJS pigmentation and gastrointestinal polyps. 72% required urgent surgery due to intestinal obstruction. 3 families had multiple cases of seizure disorder, representing 20% of cases. 28% developed cancer and two patients had more than one cancer. An STK11 mutation was found in 8 of the 9 families analyzed. A unique M136K missense mutation was noted in one family. Comparing annual live births and PJS birth records from 1970 to 2009 yielded an incidence of 1 in 155,000.

Conclusion

The Uruguayan Registry for Peutz-Jeghers patients showed a high chance of emergent surgery, epilepsy, cancer and shortened life expectancy. The M136K missense mutation is a newly reported STK 11 mutation.

One novel deletion and one splicing mutation of the LKB1 gene in two Chinese patients with Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is an uncommon autosomal dominant inherited disease, characterized by the occurrence of gastrointestinal hamartomatous polyps and pigmentation of the lips, buccal mucosa, and digits. Patients with PJS have a significant risk for developing tumors in multiple organs. Germline mutation of the LKB1 gene, which encodes a serine/threonine kinase that acts as a tumor suppressor, has been identified as a cause of PJS. The current study included two Chinese PJS probands and their available family members, as well as 200 unrelated healthy controls for comparison. Genomic DNA was extracted from the peripheral blood of these subjects. The nine coding exons and flanking introns of the LKB1 gene in the two probands and their family members were amplified by polymerase chain reaction (PCR) and then directly sequenced. Mutations identified in the patients were checked in the 200 healthy controls by PCR and denaturing high-performance liquid chromatography. Total RNA was extracted from the patient who was found to have a dubious splice site mutation and his available family members. Reverse transcription PCR was performed to identify the abnormal splicing caused by the splice site mutation. Two types of mutations were detected in the two PJS families. One type was a previously unreported 30-base-pair deletion in exon 4, and the other was an intron mutation that affected splicing. None of the 200 controls had either of these two types of mutations. The results provide support that mutation of the LKB1 gene is a cause of PJS, and expand the spectrum of LKB1 gene mutations.

Advances in the prevention, diagnosis and treatment of Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is an autosomal dominant inherited disease caused by inactivating germline mutations of the LKB1/STK11 gene and characterized by mucocutaneous pigmentation, multiple gastrointestinal hamartomatous polyps and family history. Life-threatening complications include intestinal obstruction and an increased risk for developing gastrointestinal malignancies and extraintestinal cancers. Surgery and endoscopic therapy are still main ways to manage gastrointestinal polyposis in PJS patients, and double-balloon enteroscopy has important clinical significance in the diagnosis and treatment of this disease. With the development of translational medicine, molecular targeted therapy (e.g., selective COX-2 inhibitors) brings a new approach to preventive treatment of gastrointestinal polyposis in PJS patients. Traditional Chinese medicine provides an alternative choice. In this paper, we review the recent advances in the prevention, diagnosis and treatment of PJS.

The role of components of the chromatin modification machinery in carcinogenesis of clear cell carcinoma of the ovary (Review)

Recent data have provided information regarding the profiles of clear cell carcinoma of the ovary (CCC) with adenine-thymine rich interactive domain 1A (ARID1A) mutations. The purpose of this review was to summarize current knowledge regarding the molecular mechanisms involved in CCC tumorigenesis and to describe the central role played by the aberrant chromatin remodeling. The present article reviews the English-language literature for biochemical studies on the ARID1A mutation and chromatin remodeling in CCC. ARID1A is responsible for directing the SWI/SNF complex to target promoters and regulates the transcription of certain genes by altering the chromatin structure around those genes. The mutation spectrum of ARID1A was enriched for C to T transitions. CCC and clear cell renal cell carcinoma (ccRCC) resemble each other pathogenetically. Dysfunction of the ARID1A protein, which occurs with VHL mutations in ccRCC, is responsible for loss of the assembly of the ARID1A-mediated histone H2B complex. Therefore, ARID1A acts as a chromatin remodeling modifier, which stimulates cell signaling that can lead to cell cycle arrest and cell death in the event of DNA damage. The dysfunction of ARID1A may result in susceptibility to CCC carcinogenesis through a defect in the repair or replication of damaged DNA.

A novel de novo mutation in LKB1 gene in a Chinese Peutz Jeghers syndrome patient significantly diminished p53 activity

Peutz Jeghers syndrome (PJS) is an autosomal dominant disease caused by mutations in the LKB1 gene. We screened for the LKB1 gene mutation in a Chinese PJS patient. Sequence analysis of LKB1 exons showed that there was a novel de novo mis-sense mutation of codon 16 (GAG to GGG) in exon 1 in LKB1 gene in the Chinese PJS patient. Furthermore, we observed that wild type LKB1 expression increased p53 activity, while LKB1 A47G mutation had no such effect on p53 activity, indicating that the mis-sense variant of LKB1 influenced the p53 activation function of LKB1 protein. In addition, real-time RT-PCR analysis revealed that the expression levels of p53 downstream targets were significantly diminished in affected PJS patient compared with those in unaffected parents, further confirming the roles of LKB1 and p53 in PJS pathogenesis. Therefore, a novel PJS associated LKB1 gene mutation is provided, and the roles of LKB1 and p53 in PJS pathogenesis is validated in this research.

Novel mutations in the STK11 gene in Thai patients with Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS), a rare autosomal dominant inherited disorder, is characterized by hamartomatous gastrointestinal polyps and mucocutaneous pigmentation. Patients with this syndrome have a predisposition to a variety of cancers in multiple organs. Mutations in the serine/threonine kinase 11 (STK11) gene have been identified as a major cause of PJS. Here we present the clinical and molecular findings of two unrelated Thai individuals with PJS. Mutation analysis by Polymerase Chain Reaction-sequencing of the entire coding region of STK11 revealed two potentially pathogenic mutations. One harbored a single nucleotide deletion (c.182delG) in exon 1 resulting in a frameshift leading to premature termination at codon 63 (p.Gly61AlafsX63). The other carried an in-frame 9-base-pair (bp) deletion in exon 7, c.907_915del9 (p.Ile303_Gln305del). Both deletions were de novo and have never been previously described. This study has expanded the genotypic spectrum of the STK11 gene.

Advances in research on hereditary colorectal neoplasms

Colorectal cancer is one of the most common digestive malignant tumors in China. Its incidence and mortality rates rank top among all malignant tumors. Previous studies show that nearly one-third of colorectal cancers are associated with hereditary colorectal tumors. Hereditary colorectal tumors are mainly divided into two categories: hereditary nonpolyposis colorectal cancer and hereditary colorectal polyposis. In this article, we will review the recent advances in research on hereditary colorectal neoplasms.

The regulation of protein synthesis in cancer

Translational control of cancer is a multifaceted process, involving alterations in translation factor levels and activities that are unique to the different types of cancers and the different stages of disease. Translational alterations in cancer include adaptations of the tumor itself, of the tumor microenvironment, an integral component in disease, and adaptations that occur as cancer progresses from development to local disease and ultimately to metastatic disease. Adaptations include the overexpression and increased activity of specific translation factors, the physical or functional loss of translation regulatory components, increased production of ribosomes, selective mRNA translation, and alteration of signal transduction pathways to permit unfettered activation of protein synthesis. There is intense clinical interest to capitalize on the emerging new understanding of translational control in cancer by targeting specific components of the translation apparatus that are altered in disease for the development of specific cancer therapeutics. Clinical trial data are nascent but encouraging, suggesting that translational control constitutes an important new area for drug development in human cancer.