DNA damage response-related proteins in gastric cancer: ATM, Chk2 and p53 expression and their prognostic value

The molecular crosstalk between innate immunity and DNA damage repair/response: Interactions and effects in cancers

DNA damage can lead to erroneous alterations and mutations which in turn can result into wide range of disease condition including aging, severe inflammation, and, most importantly, cancer. Due to the constant exposure to high-risk factors such as exogenous and endogenous DNA-damaging agents, cells may experience DNA damage impairing stability and integrity of the genome. These perturbations in DNA structure can arise from several mutations in the genome. Therefore, DNA Damage Repair/Response (DDR) detects and then corrects these potentially tumorigenic problems by inducing processes such as DNA repair, cell cycle arrest, apoptosis, etc. Additionally, DDR can activate signaling pathways related to immune system as a protective mechanism against genome damage. These protective machineries are ignited and spread through a network of molecules including DNA damage sensors, transducers, kinases and downstream effectors. In this review, we are going to discuss the molecular crosstalk between innate immune system and DDR, as well as their potential effects on cancer pathophysiology.

Immunohistochemical findings and clinicopathological features of breast cancers with pathogenic germline mutations in Non-BRCA genes

Deleterious germline mutations in multiple genes confer an increased breast cancer (BC) risk. Immunohistochemical (IHC) expression of protein products of mutated high-risk genes has not been investigated in BC. We hypothesized that pathogenic mutations may lead to an abnormal IHC expression pattern in the tumor cells. BCs with deleterious germline mutations in CHEK2, ATM, PALB2 & PTEN were identified. Immunohistochemistry was performed using Dako staining platform on formalin fixed paraffin embedded tumor tissue. Primary antibodies for PALB2 (ab202970), ATM [2C1(1A10)}, CHK2 (EPR4325), and PTEN (138G6) proteins were used for BCs with respective deleterious mutations. IHC expression was assessed in tumor and adjacent benign breast tissue. Total 27 BCs with 10 CHEK2, 9 ATM, 6 PALB2 & 2 PTEN deleterious germline mutations were identified. IHC staining was performed on 8 CHEK2, 7 ATM, 6 PALB2 & 2 PTEN cases. Abnormal CHEK2 IHC staining was identified in 7/8(88%) BCs. Three distinct CHK2 IHC patterns were noted: 1) Strong diffuse nuclear positivity (5 BC), 2) Null-pattern (2 BC), & 3) Normal breast-like staining in 1 BC Four of 5 (80%) strong CHK2 staining BC had missense CHEK2 mutations. Null-pattern was present with a missense & a frameshift mutation. Normal breast-like CHEK2 IHC staining pattern was present in 1 BC with CHEK2 frameshift mutation. Loss of nuclear/cytoplasmic PTEN IHC expression was noted in 2 in-situ carcinomas. Abnormal PTEN and CHK2 IHC were present in atypical ductal hyperplasia and flat epithelial atypia. ATM and PALB2 IHC expression patterns were similar in tumor cells and benign breast epithelium: mild to moderate intensity nuclear and cytoplasmic staining. We report abnormal CHEK2 IHC expression in 88% of BCs with pathogenic CHEK2 mutations. With PTEN and CHEK2 pathogenic mutations, abnormal IHC patterns are seen in early atypical proliferative lesions. IHC may be applied to identify CHEK2 & PTEN mutated BCs and precursor lesions.

mRNA Expression and Methylation of the RAD51, ATM, ATR, BRCA1, and BRCA2 Genes in Gastric Adenocarcinoma

Background

Immunohistochemical prognostic significance of the homologous recombination-related proteins RAD51, ATM, BRCA1, and BRCA2 is known in gastric adenocarcinoma, one of the deadliest cancers.

Objective and design

This retrospective cohort study aimed to evaluate mRNA expression and promoter methylation of some homologous recombination-related genes in this neoplasm.

Methods

We evaluated mRNA expression and methylation of RAD51, ATM, ATR, BRCA1, and BRCA2 in tumor and non-tumor frozen samples from gastrectomy specimens by RT-qPCR and MS-HRM, correlating our results with previous immunohistochemistry data and prognostic features.

Results

RAD51, ATR, BRCA1, BRCA2, and ATM mRNA expression was detected in 93.75% (45/48), 93.75% (45/48), 91.67% (44/48), 83.33% (40/48), and 89.58% (43/48) of the tumors; partial or complete methylation, in 94.87% (37/39), 0 (0/42), 97.56% (40/41), 100% (41/41), and 0 (0/40), respectively. Most gene pairs showed significant weak to moderate positive correlations of tumoral mRNA expression with each other: RAD51 with ATR (P = .027), BRCA1 (P < .001), and BRCA2 (P < .001); ATR with BRCA1 (P = .007), and ATM (P = .001); BRCA1 with BRCA2 (P = 0.001). BRCA1 mRNA was reduced in tumors compared with non-neoplastic mucosa (0.345 vs 1.272, P = .015) and, excluding neoadjuvant therapy cases, in T3 to T4 tumors compared with T2 (0.414 vs 0.954, P = .035). Greater tumoral RAD51 mRNA levels correlated with perineural invasion (1.822 vs 0.725, P = .010) and death (1.664 vs 0.929, P = .036), but not with survival time. There was an inverse association between nuclear immunohistochemical positivity for ATR and its mRNA levels (0.487 vs 0.907, P = .032), and no significant correlation for the other markers.

Conclusions

Our results suggest RAD51, BRCA1, and BRCA2 methylation as a frequent epigenetic mechanism in gastric cancer, support the hypothesis that reduced BRCA1 expression participates in disease progression, and show an association between RAD51 mRNA and perineural invasion and mortality that may be considered unexpected, considering the former immunohistochemical studies. The lack of correlation between immunohistochemistry and mRNA, and even the inverse association, for ATR, can be seen as indicative of action of post-transcriptional or post-translational regulatory mechanisms, to be better investigated.

Could Inhibiting the DNA Damage Repair Checkpoint Rescue Immune-Checkpoint-Inhibitor-Resistant Endometrial Cancer?

Endometrial cancer (EC) is increasingly undermining female health worldwide, with poor survival rates for advanced or recurrent/metastatic diseases. The application of immune checkpoint inhibitors (ICIs) has opened a window of opportunity for patients with first-line therapy failure. However, there is a subset of patients with endometrial cancer who remain insensitive to immunotherapy alone. Therefore, it is necessary to develop new therapeutic agents and further explore reliable combinational strategies to optimize the efficacy of immunotherapy. DNA damage repair (DDR) inhibitors as novel targeted drugs are able to generate genomic toxicity and induce cell death in solid tumors, including EC. Recently, growing evidence has demonstrated the DDR pathway modulates innate and adaptive immunity in tumors. In this review, we concentrate on the exploration of the intrinsic correlation between DDR pathways, especially the ATM-CHK2-P53 pathway and the ATR-CHK1-WEE1 pathway, and oncologic immune response, as well as the feasibility of adding DDR inhibitors to ICIs for the treatment of patients with advanced or recurrent/metastatic EC. We hope that this review will offer some beneficial references to the investigation of immunotherapy and provide a reasonable basis for "double-checkpoint inhibition" in EC.

Systematic Review and Meta-analysis of TP53, HER2/ERBB2, KRAS, APC, and PIK3CA Genes Expression Pattern in Gastric Cancer

Background: With a global prevalence of about 10%, gastric cancer is among the most prevalent cancers. Currently, there has been an ongoing trend toward investigating genetic disruptions in different cancers because they can be used as a target-specific therapy. We aimed to systemically review some gene expression patterns in gastric cancer. Methods: The current systematic review was designed and executed in 2020. Scopus, PubMed, Cochrane Library, Google Scholar, web of knowledge, and Science Direct were searched for relevant studies. A manual search of articles (hand searching), reference exploring, checking for grey literature, and seeking expert opinion were also done. Results: In this review, 65 studies were included, and the expression pattern of HER2/ ERBB2, ER1/Erb1/EGFR, PIK3CA, APC, KRAS, ARID1A, TP53, FGFR2 and MET was investigated. TP53, APC, KRAS, and PIK3CA mutation cumulative frequency were 24.8 (I²=95.05, Q value=525.53, df=26, P<0.001), 7.2 (I²=89.79, Q value=48.99, df=5, P<0.001), 7.8 (I²=93.60, Q value=140.71, df=9, P=0.001) and 8.6 (I²=80.78, Q value=525.53, df=9, P<0.001) percent, respectively. Overexpression was investigated for HER1/ Erb1/EGFR, PIK3CA, APC, KRAS, ARID1A, TP53, CCND1, FGFR2, MET and MYC. The frequency of TP53 and HER2/ERBB2 were 43.1 (I²=84.06, Q value=58.09, df=9, P<0.001) and 20.8 (I²=93.61, Q value=234.89, df=15, P<0.001) percent, respectively. Conclusion: More research is encouraged to investigate the genes for which we could not perform a meta-analysis.

ILP-2: A New Bane and Therapeutic Target for Human Cancers

Inhibitor of apoptosis protein-related-like protein-2 (ILP-2), also known as BIRC-8, is a member of the inhibitor of apoptosis protein (IAPs) family, which mainly encodes the negative regulator of apoptosis. It is selectively overexpressed in a variety of human tumors and can help tumor cells evade apoptosis, promote tumor cell growth, increase tumor cell aggressiveness, and appears to be involved in tumor cell resistance to chemotherapeutic drugs. Several studies have shown that downregulation of ILP-2 expression increases apoptosis, inhibits metastasis, reduces cell growth potential, and sensitizes tumor cells to chemotherapeutic drugs. In addition, ILP-2 inhibits apoptosis in a unique manner; it does not directly inhibit the activity of caspases but induces apoptosis by cooperating with other apoptosis-related proteins. Here, we review the current understanding of the various roles of ILP-2 in the apoptotic cascade and explore the use of interfering ILP-2, and the combination of related anti-tumor agents, as a novel strategy for cancer therapy.

Prognostic Value of the Immunohistochemical Expression of RAD51 and BRCA2 in Gastric Adenocarcinoma

Current scientific literature lacks data on the prognostic value of the expression of RAD51 and BRCA2 in gastric adenocarcinoma. Therefore, we aimed to evaluate those and other homologous recombination-related proteins (ATM, ATR, BRCA1, CHK2, γH2AX, p53) in gastric cancer, assessing their correlation with clinical prognosis. Paraffin-embedded samples were obtained from surgical specimens collected in total or subtotal gastrectomy procedures. Between 2008 and 2017, 121 patients with advanced gastric adenocarcinoma underwent surgical resection and were included in this study. Negativity for nuclear RAD51 correlated with vascular invasion, lymph node metastasis, larger tumor size, and lower overall survival and disease-free survival in univariate analysis. However, nuclear RAD51-negative cases presented better response rates to adjuvant therapy than the positive ones. Nuclear ATR negativity correlated with larger tumor size and a higher histological grade. Positivity for ATM was associated with more prolonged disease-free survival. Positivity for nuclear BRCA2 correlated with lower overall survival and diffuse histological type, whereas its high expression was associated with vascular invasion. Nevertheless, tumors positive for nuclear BRCA2 were more frequently low grade in the intestinal histological type. Our findings indicate that RAD51 and BRCA2 are valuable immunohistochemical prognostic markers in gastric adenocarcinoma.

Comprehensive analysis to identify DNA damage response-related lncRNA pairs as a prognostic and therapeutic biomarker in gastric cancer

OBJECTIVE

Gastric cancer (GC) is the fifth most common malignancy and the fourth leading cause of cancer-related mortality worldwide. The identification of valuable predictive signatures to improve the prognosis of patients with GC is becoming a realistic prospect. DNA damage response-related long noncoding ribonucleic acids (drlncRNAs) play an important role in the development of cancers. However, their prognostic and therapeutic values remain sparse in gastric cancer (GC).

METHODS

We obtained the transcriptome data and clinical information from The Cancer Genome Atlas Stomach Adenocarcinoma (TCGA-STAD) cohort. Co-expression network analyses were performed to discover functional modules using the igaph package. Subsequently, lncRNA pairs were identified by bioinformation analysis, and prognostic pairs were determined by univariate analysis, respectively. In addition, we utilized least absolute shrinkage and selection operator (LASSO) cox regression analysis to construct the risk model based on lncRNA pairs. Then, we distinguished between the high- or low- risk groups from patients with GC based on the optimal model. Finally, we reevaluated the association between risk score and overall survival, tumor immune microenvironment, specific tumor-infiltrating immune cells related biomarkers, and the sensitivity of chemotherapeutic agents.

RESULTS

32 drlncRNA pairs were obtained, and a 17-drlncRNA pairs signature was constructed to predict the overall survival of patients with GC. The ROC was 0.797, 0.812 and 0.821 at 1, 2, 3 years, respectively. After reclassifying these patients into different risk-groups, we could differentiate between them based on negative overall survival outcome, specialized tumor immune infiltration status, higher expressed immune cell related biomarkers, and a lower chemotherapeutics sensitivity. Compared with previous models, our model showed better performance with a higher ROC value.

CONCLUSION

The prognostic and therapeutic signature established by novel lncRNA pairs could provide promising prediction value, and guide individual treatment strategies in the future.

High FAM189B Expression and Its Prognostic Value in Patients with Gastric Cancer

The clinical significance of the family with sequence similarity 189 member B (FAM189B) gene remains largely unknown in gastric cancer (GC). A comprehensive investigation combining multiple detection methods was carried out in the current study to unveil the clinical implications and prospective molecular characterization of FAM189B protein and mRNA in GC. The protein level of FAM189B was clearly upregulated in the tumor tissues of GC as compared to noncancerous gastric tissues with 179 GC cases and 147 noncancerous gastric controls assessed by immunohistochemistry. The upregulation of the FAM189B protein was also found in the more deteriorating period of the tumor, as there were increasing trends in the groups of larger tumors, with lymph node metastasis, a further advanced clinical stage, and a higher histological grade. Next, we focused on the mRNA level of FAM189B in GC tissues using various high-throughput data. After the screening of GEO, ArrayExpress, and SRA, we finally achieved 18 datasets, including an RNA sequencing dataset of TCGA. Altogether, 1095 cases of GC tissue samples were collected, with 305 unique examples of noncancerous controls. Concerning the mRNA level of FAM189B in GC, the final standard mean difference (SMD) was 0.46 and the area under the curve (AUC) was 0.79 for the upregulation of FAM189B mRNA, which confirmed that the FAM189B mRNA level was also markedly upregulated in GC tissues and comparable to its protein level. The survival analysis showed that the higher expression of FAM189B was a risk factor for the overall survival, first progression, and postprogression survival of GC. For the Affymetrix ID 1555515_a_at of FAM189B, the higher expression level of FAM189B predicted a lower overall survival, first progression survival, and postprogression survival with the hazard ratio (HR) being 1.56 (1.24, 1.95), 1.69 (1.32, 2.17), and 1.97 (1.5, 2.6), respectively. For the Affymetrix ID 203550_s_at of FAM189B, a similar result could be found with corresponding HR being 1.49 (1.24, 1.8), 1.49 (1.21, 1.83), and 1.66 (1.32, 2.08), respectively. The interaction of MEM, COXPRESdb coexpressed genes, and DEGs of GC finally generated 368 genes, and the pathway of the cell cycle was the top pathway enriched by KEGG. In conclusion, the overexpression of the FAM189B protein and mRNA might enhance the incidence of GC.

Expression of Indoleamine 2, 3-dioxygenase 1 (IDO1) and Tryptophanyl-tRNA Synthetase (WARS) in Gastric Cancer Molecular Subtypes

AIMS

Developments in genomic pathology have led to novel molecular classification schemes in gastric cancers. Two of these new subtypes, Epstein-Barr virus (EBV)-associated and microsatellite instability-high (MSI-H), are associated with a dominant T-cell-mediated immune response. The roles of the immune modulators, indoleamine 2, 3-dioxygenase 1 (IDO1) and tryptophanyl-tRNA synthetase (WARS), have not been investigated in the context of this classification.

METHODS AND RESULTS

Using in situ hybridization and immunohistochemistry we subclassified 421 primary gastric adenocarcinomas into 5 subtypes, EBV-associated, epithelial to mesenchymal transition, MSI-H, p53-aberrant, and p53-wildtype tumors. Tumor-infiltrative lymphocytes were counted and protein expression of IDO1 and WARS was graded on tissue microarrays of these 421 tumors. High tumor-infiltrative lymphocytes as well as high expression of both IDO1 and WARS was found in EBV and MSI-H tumors. The prognostic effects of IDO1 and WARS expression were tumor subtype dependent. Although high expression levels of IDO1 and WARS were associated with poor prognosis in p53-aberrant, p53-wildtype, and all cancers combined, WARS expression was associated with better prognosis in MSI tumors.

CONCLUSIONS

The immunomodulators, IDO1 and WARs, are upregulated and have prognostic significance in EBV-associated and MSI-H tumors. Novel therapies targeting these proteins should be considered in the treatment of these patients.

Predictive and Prognostic Value of DNA Damage Response Associated Kinases in Solid Tumors

Dysfunctional DNA repair with subsequent genome instability and high mutational burden represents a major hallmark of cancer. In established malignant tumors, increased DNA repair capacity mediates resistance to DNA-damaging therapeutics, including cytotoxic drugs, radiotherapy, and selected small molecules including inhibitors of poly (ADP-ribose) polymerase (PARP), Ataxia Telangiectasia Mutated (ATM), ataxia telangiectasia and Rad3-related protein (ATR), and Wee1 kinase (Wee1). In addition, DNA repair deficiency is not only associated with sensitivity to selected anticancer drugs, but also with increased mutagenicity and increased neoantigen load on tumor cells, resulting in increased immunogenicity and improved response to CTLA4- or PD-(L)1 targeting monoclonal antibodies. DNA damage response (DDR) is composed of complex signalling pathways, including the sensing of the DNA damage, signal transduction, cellular response pathways to DNA damage, and activation of DNA repair. DNA double strand breaks (DSBs) are the most dangerous form of DNA damage. Tumor cells are characterised by frequent accumulation of DSBs caused by either endogenous replication stress or the impact of cancer treatment, most prominently chemotherapy and radiotherapy. Therefore, response of cancer cells to DSBs represents a crucial mechanism for how tumors respond to systemic treatment or radiotherapy, and how resistance develops. Ample clinical evidence supports the importance of DDR associated kinases as predictive and prognostic biomarkers in cancer patients. The ATM-CHK2 and ATR-CHK1-WEE1 pathways initiate DNA DSB repair. In the current review, we focus on major DDR associated kinases including ATM, ATR, CHK1, CHK2, and WEE1, and discuss their potential prognostic and predictive value in solid malignancies.

High-Throughput Sequencing of Gastric Cancer Patients: Unravelling Genetic Predispositions Towards an Early-Onset Subtype

Background: Gastric cancer is the fourth most common cause of cancer-related death. Currently, it is broadly accepted that the molecular complexity and heterogeneity of gastric cancer, both inter- and intra-tumor, display important barriers for finding specific biomarkers for the early detection and diagnosis of this malignancy. Early-onset gastric cancer is not as prevalent as conventional gastric carcinoma, but it is a preferable model for studying the genetic background, as young patients are less exposed to environmental factors, which influence cancer development. Aim: The main objective of this study was to reveal age-dependent genotypic characteristics of gastric cancer subtypes, as well as conduct mutation profiling for the most frequent alterations in gastric cancer development, using targeted next-generation sequencing technology. Patients and methods: The study group included 53 patients, consisting of 18 patients with conventional gastric cancer and 35 with an early-onset subtype. The DNA of all index cases was used for next-generation sequencing, employing a panel of 94 genes and 284 single nucleotide polymorphisms (SNPs) (TruSight Cancer Panel, Illumina), which is characteristic for common and rare types of cancer. Results: From among the 53 samples processed for sequencing, we were able to identify seven candidate genes (STK11, RET, FANCM, SLX4, WRN, MEN1, and KIT) and nine variants among them: one splice_acceptor, four synonymous, and four missense variants. These were selected for the age-dependent differentiation of gastric cancer subtypes. We found four variants with C-Score ≥ 10, as 10% of the most deleterious substitutions: rs1800862 (RET), rs10138997 (FANCM), rs2230009 (WRN), and rs2959656 (MEN1). We identified 36 different variants, among 24 different genes, which were the most frequent genetic alterations among study subjects. We found 16 different variants among the genes that were present in 100% of the total cohort: SDHB (rs2746462), ALK (rs1670283), XPC (rs2958057), RECQL4 (rs4925828; rs11342077, rs398010167; rs2721190), DDB2 (rs326212), MEN1 (rs540012), AIP (rs4930199), ATM (rs659243), HNF1A (rs1169305), BRCA2 (rs206075; rs169547), ERCC5 (rs9514066; rs9514067), and FANCI (rs7183618). Conclusions: The technology of next-generation sequencing is a useful tool for studying the development and progression of gastric carcinoma in a high-throughput way. Our study revealed that early-onset gastric cancer has a different mutation frequency profile in certain genes compared to conventional subtype.

Expression of BAP1 and ATM proteins: Association with AJCC tumor category in uveal melanoma

BACKGROUND

Our aim is to detect the association of BAP1 with ATM protein with AJCC tumor category and its prognostic significance.

METHODS

Based on AJCC tumor category, 69 patients samples were categorized into group A (LBD > 15 mm & tumor thickness ≥ 8 mm) and group B (LBD ≤ 15 mm & tumor thickness < 8 mm) subjected to immunohistochemistry to assess the nuclear expression of ATM and BAP1 proteins. Mutational analysis of BAP1 was performed on five samples from each group.

RESULTS

Group A tumors showed insertion mutation of BAP1 gene while there was no mutation seen in group B tumor. At translational level loss of ATM and BAP1 was found in 65% and 66% of cases respectively. Loss of ATM with BAP1 was seen in 55% of cases which was more frequent in group A which was statically significant with metastasis (p = 0.006), advanced tumor staging (p = 0.021) and reduced metastasis-free survival (p = 0.048). On multivariate analysis loss of ATM along with BAP1 came out to be an independent prognostic marker (p = 0.035).

CONCLUSION

Our data suggest that loss of BAP1 along with ATM might serve as a potential prognostic indicator in patients with an advanced AJCC tumor category, which leads to an increased risk of metastasis.

Hsa_circ_0001546 acts as a miRNA-421 sponge to inhibit the chemoresistance of gastric cancer cells via ATM/Chk2/p53-dependent pathway

Circular RNAs (circRNAs) are a new class of noncoding RNAs, play a crucial role in tumor initiation and development. Hsa_circ_0001546 is a novel circular RNA that was downregulated in gastric cancer (GC) tissues, however its function and mechanism in GC has not been studied. Our study verified that circ_0001546 was decreased in GC and correlated with the poor prognosis. Next, Pull-down assay and dual-luciferase reporter assay verified that miR-421 was a target of circ_0001546 while ATM (Ataxia telangiectasia mutated) was target by miR-421. Overexpression of circ_0001546 inhibited the proliferation and chemoresistance of HGC-27 cells, and increased the expression of ATM. In addition, circ_0001546 overexpression reversed the effect of miR-421 overexpression. What is more, circ_0001546 inhibits the chemoresistance of HGC-27 cells to L-OPH (Oxaliplatin) may through the activation of the ATM/checkpoint kinase 2 (Chk2)/p53-dependent signaling pathway. In summary, our study proved that circ_0001546 sponges miR-421 to upregulate the expression level of ATM and inhibit the proliferation and chemoresistance through the activation of the ATM/Chk2/p53-dependent pathway.

High-level expression of protein tyrosine phosphatase non-receptor 12 is a strong and independent predictor of poor prognosis in prostate cancer

BACKGROUND

Protein tyrosine phosphatase non-receptor 12 (PTPN12) is ubiquitously tyrosine phosphatase with tumor suppressive properties.

METHODS

PTPN12 expression was analyzed by immunohistochemistry on a tissue microarray with 13,660 clinical prostate cancer specimens.

RESULTS

PTPN12 staining was typically absent or weak in normal prostatic epithelium but seen in the majority of cancers, where staining was considered weak in 26.5%, moderate in 39.9%, and strong in 4.7%. High PTPN12 staining was associated with high pT category, high classical and quantitative Gleason grade, lymph node metastasis, positive surgical margin, high Ki67 labeling index and early prostate specific antigen recurrence (p < 0.0001 each). PTPN12 staining was seen in 86.4% of TMPRSS2:ERG fusion positive but in only 58.4% of ERG negative cancers. Subset analyses discovered that all associations with unfavorable phenotype and prognosis were markedly stronger in ERG positive than in ERG negative cancers but still retained in the latter group. Multivariate analyses revealed an independent prognostic impact of high PTPN12 expression in all cancers and in the ERG negative subgroup and to a lesser extent also in ERG positive cancers. Comparison with 12 previously analyzed chromosomal deletions revealed that high PTPN12 expression was significantly associated with 10 of 12 deletions in ERG negative and with 7 of 12 deletions in ERG positive cancers (p < 0.05 each) indicating that PTPN12 overexpression parallels increased genomic instability in prostate cancer.

CONCLUSIONS

These data identify PTPN12 as an independent prognostic marker in prostate cancer. PTPN12 analysis, either alone or in combination with other biomarkers might be of clinical utility in assessing prostate cancer aggressiveness.

Loss of CHEK2 Predicts Progression in Stage pT1 Non-Muscle-Invasive Bladder Cancer (NMIBC)

Downregulation of checkpoint protein kinase 2 (CHEK2), which is involved in DNA repair, is associated with poorer outcome in various tumors. Little is known about the role of CHEK2 in urothelial carcinoma of the bladder (UCB). In the present study, we investigated the prognostic impact of CHEK2 protein expression in stage pT1 UCB. This retrospective, single-center analysis was carried out in a cohort of patients initially diagnosed with a pT1 UCB between 2007 and 2015. Immunohistochemical (IHC) staining of CHEK2 was performed. CHEK2 expression was correlated with recurrence-free survival (RFS), progression-free survival (PFS), and cancer-specific survival (CSS) using Kaplan-Meier analysis and multivariable Cox regression analysis. The analysis included 126 patients (86% male, median age 71 years). Loss of immunohistochemical protein expression of CHEK2 (<10%) was associated with significantly worse PFS (p = 0.041). Likewise, CHEK2 loss identified a subgroup of patients with worse PFS in the high-risk groups with concomitant CIS (p = 0.044), multifocal tumors (p < 0.001) and tumor grading G3 according to WHO1973 (p = 0.009). Multivariable Cox regression analysis revealed both loss of CHEK2 expression (HR: 4.18, 95%-CI: 1.35-12.93; p = 0.013) and multifocal tumors (HR: 4.53, 95%-CI:1.29-15.92; p = 0.018) as the only predictive factors for progression. Loss of IHC expression of CHEK2 in pT1 UCB is an independent predictor for progression to muscle-invasive disease and is also associated with worse PFS. This could help to identify high-risk patients who would benefit from early cystectomy.

Prognostic relevance of ATM protein in uveal melanoma and its association with clinicopathological factors

PURPOSE

Uveal melanoma (UM) is an intraocular malignancy commonly arising from choroid which can cause visual loss or metastasis. Ataxia-telangiectasia mutated (ATM) protein is an activator of DNA damage response and its role in uveal melanoma (UM) is still unexplored. Therefore, the study aims to detect the expression and localization of ATM protein and its association with clinicopathological parameters METHODS: Expression of nuclear ATM (nATM) was investigated on 69 formalin fixed paraffin embedded choroidal melanoma samples by immunohistochemistry and validated by western blotting. Results were then correlated with clinical and histopathological parameters. Prognostic significance was determined by the Kaplan-Meier analysis and the multivariate analysis by Cox's hazard proportional method.

RESULTS

Loss of nATM was observed in 65% of cases, which was statistically significant with the reduced disease-free survival (p = 0.042). This loss was more frequently found in cases with high-risk histopathological factors like epithelioid cell type, tumor infiltrating lymphocytes and high pigmentation which might help in the progression of melanoma. On multivariate analysis, extraocular spread and loss of nATM were found to be independent prognostic factors (p < 0.05).

CONCLUSION

Our data suggest that loss of nATM protein might serve as a poor prognostic marker in the pathogenesis of uveal melanoma which may lead to increased risk of metastasis.

Expression of DNA damage response proteins in gastric cancer: Comprehensive protein profiling and histological analysis

Gastric cancer is the third major cause of cancer-related mortality in Japan. The aim of this study was to identify a factor implicated in the biology of gastric cancer by comprehensive protein profiling. Protein profiling was carried out by liquid chromatography-tandem mass spectrometry, using formalin-fixed paraffin-embedded specimens of 17 gastric cancer cases. Pathway analysis and orthogonal partial least square-discriminant analysis suggested the significant expression of ribonucleoproteins, heterogeneous nuclear ribonucleoproteins, interleukin binding factor 2 (ILF2), KU70 and KU80, which are involved in DNA damage response (DDR). Thus, the expression and phosphorylation levels of KU70, ILF2, CHK1 and CHK2 were examined by immunohistochemistry in 42 cases of gastric cancer. The expressions of ILF2 and CHK1 were unaffected in all cases. The expression and phosphorylation of CHK2 were absent in 2 cases. Despite the expression of proteins, the phosphorylation of KU70 and CHK2 appeared to be impaired in 1 and 4 cases, respectively. In 7 out of 42 cases (17%), DDR appeared to be impaired. Recurrence was noted in 2 out of these 7 cases (29%), whereas the recurrence was noted in 2 out of the remaining 35 cases (6%). The expression levels of KU70, ILF2, CHK1, CHK2 and TP53 were further examined in 4 gastric cancer cell lines. The expression and phosphorylation levels following exposure to ultraviolet radiation were abnormal in the 3 cell lines. The normal consecutive phosphorylation of CHK1 and CHK2, the upregulation of TP53 and an increase in apoptotic cell death following exposure to ultraviolet radiation was detected only in one cell line, suggesting that the preserved functions of DDR and TP53 are necessary for the determination of cell fate. It is thus suggested that DDR plays an important role in the pathobiology of gastric cancers.

Genomic landscape of gastric cancer: molecular classification and potential targets

Gastric cancer imposes a considerable health burden worldwide, and its mortality ranks as the second highest for all types of cancers. The limited knowledge of the molecular mechanisms underlying gastric cancer tumorigenesis hinders the development of therapeutic strategies. However, ongoing collaborative sequencing efforts facilitate molecular classification and unveil the genomic landscape of gastric cancer. Several new drivers and tumorigenic pathways in gastric cancer, including chromatin remodeling genes, RhoA-related pathways, TP53 dysregulation, activation of receptor tyrosine kinases, stem cell pathways and abnormal DNA methylation, have been revealed. These newly identified genomic alterations await translation into clinical diagnosis and targeted therapies. Considering that loss-of-function mutations are intractable, synthetic lethality could be employed when discussing feasible therapeutic strategies. Although many challenges remain to be tackled, we are optimistic regarding improvements in the prognosis and treatment of gastric cancer in the near future.

Evaluation of Fibroblast Growth Factor Receptor 2 Expression, Heterogeneity and Clinical Significance in Gastric Cancer

BACKGROUND

We aimed to evaluate the protein and mRNA expression of fibroblast growth factor receptor 2 (FGFR2) by immunohistochemistry (IHC) and mRNA in situ hybridization (ISH), respectively, and to assess the heterogeneity of FGFR2 expression in gastric cancer (GC).

METHODS

A tissue microarray containing 362 surgically resected GC tissues and 135 matched metastatic lymph nodes was evaluated using FGFR2b IHC and FGFR2 ISH. FGFR2 fluorescence ISH was also performed in 188 cases.

RESULTS

All FGFR2-amplified cases (5 of 188) showed FGFR2b protein and FGFR2 mRNA overexpression (p < 0.001), and FGFR2 amplification was not identified in FGFR2b IHC- and FGFR2 mRNA ISH-negative cases. Kaplan-Meier survival analysis revealed that FGFR2b protein and FGFR2 mRNA overexpression was significantly associated with a poor overall survival (p < 0.001 and p = 0.012, respectively), and multivariate analyses showed that FGFR2 mRNA overexpression was an independent biomarker of a poor overall survival. Intratumoral heterogeneity of FGFR2b protein and FGFR2 mRNA overexpression was observed in 5 of 9 (55.5%) and 18 of 21 (85.7%) cases, respectively. Discordant FGFR2b and FGFR2 expression results between primary and matched metastatic lymph nodes were observed in 5 of 9 (55.5%) and 4 of 14 (28.6%) cases, respectively.

CONCLUSIONS

Intratumoral heterogeneity and discordant FGFR2b expression in primary tumors and metastatic lymph nodes are common in GC.

Curcumin induces apoptosis in p53-null Hep3B cells through a TAp73/DNp73-dependent pathway

Curcumin has anticancer functions in various tumors. It has been shown to induce apoptosis through p53-dependent pathways. p73 gene is a member of the p53 family which encodes both a tumor suppressor (transactivation-competent p73 (TAp73)) and a putative oncogene (dominant-negative p73 (DNp73)); the former shares similarity with the tumor suppressor p53, and the latter behaves as dominant-negative proteins that interfere with the activity of TAp73. To understand the p73-dependent mechanisms that are engaged during curcumin-induced apoptosis, we established a p73 overexpression cell models using p53-deficient Hep3B cells (Hep3B(TAp73/DNp73)). Our results demonstrated that curcumin at concentrations of 40 and 80 μM induced DNA damage, increased TAp73/DNp73 ratio, and also led to apoptosis in the Hep3B(TAp73/DNp73) cells. The apoptotic cell death was concurrent with the loss of mitochondrial membrane potential; release of cytochrome c from mitochondria; and the cleavage of caspase 9, caspase 3, and poly(ADP-ribose) polymerase (PARP). These results demonstrated a p73-dependent mechanism for curcumin-induced apoptosis that involves the mitochondria-mediated pathway.

Prognostic Significance of Nuclear Phospho-ATM Expression in Melanoma

UV radiation induced genomic instability is one of the leading causes for melanoma. Phosphorylation of Ataxia Telangiectasia Mutated (ATM) is one of the initial events that follow DNA damage. Phospho-ATM (p-ATM) plays a key role in the activation of DNA repair and several oncogenic pathways as well as in the maintenance of genomic integrity. The present study was therefore performed to understand the significance of p-ATM in melanoma progression and to correlate it with patient prognosis. Tissue microarray and immunohistochemical analysis were employed to study the expression of p-ATM in melanoma patients. A total of 366 melanoma patients (230 primary melanoma and 136 metastatic melanoma) were used for the study. Chi-square test, Kaplan-Meier, univariate and multivariate Cox regression analysis were used to elucidate the prognostic significance of p-ATM expression. Results revealed that both loss of, and gain in, p-ATM expression were associated with progression of melanoma from normal nevi to metastatic melanoma. Patients whose samples showed negative or strong p-ATM staining had significantly worse 5-year survival compared to patients who had weak to moderate expression. Loss of p-ATM expression was associated with relatively better 5-year survival, but the corresponding 10-year survival curve almost overlapped with that of strong p-ATM expression. p-ATM expression was found to be an independent prognostic factor for 5-year but not for 10-year patient survival. In conclusion our findings show that loss of p-ATM expression and gain-in p-ATM expression are indicators of worse melanoma patient survival.

Molecular Links between Alcohol and Tobacco Induced DNA Damage, Gene Polymorphisms and Patho-physiological Consequences: A Systematic Review of Hepatic Carcinogenesis

Chronic alcohol and tobacco abuse plays a crucial role in the development of different liver associated disorders. Intake promotes the generation of reactive oxygen species within hepatic cells exposing their DNA to continuous oxidative stress which finally leads to DNA damage. However in response to such damage an entangled protective repair machinery comprising different repair proteins like ATM, ATR, H2AX, MRN complex becomes activated. Under abnormal conditions the excessive reactive oxygen species generation results in genetic predisposition of various genes (as ADH, ALDH, CYP2E1, GSTT1, GSTP1 and GSTM1) involved in xenobiotic metabolic pathways, associated with susceptibility to different liver related diseases such as fibrosis, cirrhosis and hepatocellular carcinoma. There is increasing evidence that the inflammatory process is inherently associated with many different cancer types, including hepatocellular carcinomas. The generated reactive oxygen species can also activate or repress epigenetic elements such as chromatin remodeling, non-coding RNAs (micro-RNAs), DNA (de) methylation and histone modification that affect gene expression, hence leading to various disorders. The present review provides comprehensive knowledge of different molecular mechanisms involved in gene polymorphism and their possible association with alcohol and tobacco consumption. The article also showcases the necessity of identifying novel diagnostic biomarkers for early cancer risk assessment among alcohol and tobacco users.

Low ATM protein expression and depletion of p53 correlates with olaparib sensitivity in gastric cancer cell lines

Small-molecule inhibitors of poly (ADP-ribose) polymerase (PARP) have shown considerable promise in the treatment of homologous recombination (HR)-defective tumors, such as BRCA1- and BRCA2-deficient breast and ovarian cancers. We previously reported that mantle cell lymphoma cells with deficiency in ataxia telangiectasia mutated (ATM) are sensitive to PARP-1 inhibitors in vitro and in vivo. Here, we report that PARP inhibitors can potentially target ATM deficiency arising in a solid malignancy. We show that ATM protein expression varies between gastric cancer cell lines, with NUGC4 having significantly reduced protein levels. Significant correlation was found between ATM protein expression and sensitivity to the PARP inhibitor olaparib, with NUGC4 being the most sensitive. Moreover, reducing ATM kinase activity using a small-molecule inhibitor (KU55933) or shRNA-mediated depletion of ATM protein enhanced olaparib sensitivity in gastric cancer cell lines with depletion or inactivation of p53. Our results demonstrate that ATM is a potential predictive biomarker for PARP-1 inhibitor activity in gastric cancer harboring disruption of p53, and that combined inhibition of ATM and PARP-1 is a rational strategy for expanding the utility of PARP-1 inhibitors to gastric cancer with p53 disruption.

Expression and significance of the novel tumor-suppressor gene SMG-1 in hepatocellular carcinoma

Recent studies have demonstrated that SMG-1, a newly characterized member of the family of phosphatidylinositol 3-kinase-related protein kinases (PIKKs), is involved in tumorigenesis as a new tumor suppressor. However, its expression and significance in hepatocellular carcinoma (HCC) remain obscure. The present study investigated SMG-1 expression in HCC tissue specimens, aimed at defining the association with clinicopathological significance. Both immunohistochemistry and qRT-PCR were employed to analyze SMG-1 expression in 157 HCC and corresponding distant normal tissue specimens. The results revealed that expression of SMG-1 was significantly lower in the HCC tissue specimens than that in the distant normal tissues. Moreover, a lower expression level of SMG-1 was significantly correlated with serum α-fetoprotein level (P=0.001), poorly differentiated tumors (P=0.009) and more advanced TNM stage (P<0.001). Further study showed that SMG-1 expression was exactly associated with tumor differentiation and clinical stage in HCC. Kaplan-Meier analysis indicated that low SMG-1 expression was related to poor overall survival, and the prognostic impact of SMG-1 was further confirmed by stratified survival analysis. Importantly, multivariate analysis revealed that low SMG-1 expression was an independent prognostic marker for an unfavorable overall survival. We conclude that SMG-1 is downregulated in HCC and may represent a promising biomarker for predicting the prognosis of HCC, including the prognosis of early-stage patients.