Mutation profiling in gallbladder cancer in Indian population

Gallbladder cancer: Progress in the Indian subcontinent

Gallbladder cancer (GBC) is one of the commonest biliary malignancies seen in India, Argentina, and Japan. The disease has dismal outcome as it is detected quite late due to nonspecific symptoms and signs. Early detection is the only way to improve the outcome. There have been several advances in basic as well as clinical research in the hepatobiliary and pancreatic diseases in the West and other developed countries but not enough has been done in GBC. Therefore, it is important and the responsibility of the countries with high burden of GBC to find solutions to the many unanswered questions like etiopathogenesis, early diagnosis, treatment, and prognostication. As India being one of the largest hubs for GBC in the world, it is important to know how the country has progressed on GBC. In this review, we will discuss the outcome of the publications from India highlighting the work and the developments taken place in past several decades both in basic and clinical research.

Gallbladder Cancer: Current Insights in Genetic Alterations and Their Possible Therapeutic Implications

Due to the fast progression in molecular technologies such as next-generation sequencing, knowledge of genetic alterations in gallbladder cancer (GBC) increases. This systematic review provides an overview of frequently occurring genetic alterations occurring in GBC and their possible therapeutic implications. A literature search was performed utilizing PubMed, EMBASE, Cochrane Library, and Web of Science. Only studies reporting genetic alterations in human GBC were included. In total, data were extracted from 62 articles, describing a total of 3893 GBC samples. Frequently detected genetic alterations (>5% in >5 samples across all studies) in GBC for which targeted therapies are available in other cancer types included mutations in ATM, ERBB2, and PIK3CA, and ERBB2 amplifications. High tumor mutational burden (TMB-H) and microsatellite instability (MSI-H) were infrequently observed in GBC (1.7% and 3.5%, respectively). For solid cancers with TMB-H or MSI-H pembrolizumab is FDA-approved and shows an objective response rates of 50% for TMB-H GBC and 41% for MSI-H biliary tract cancer. Only nine clinical trials evaluated targeted therapies in GBC directed at frequently altered genes (ERBB2, ARID1A, ATM, and KRAS). This underlines the challenges to perform such clinical trials in this rare, heterogeneous cancer type and emphasizes the need for multicenter clinical trials.

Genetic mutational analysis of β-catenin gene affecting GSK-3β phosphorylation plays a role in gallbladder carcinogenesis: Results from a case control study

This manuscript has reported different mutations of β-catenin gene in gallbladder cancer patients which affect GSK-3β phosphorylation site.

PURPOSE

Gallbladder carcinoma (GBC) is a relatively rare and fatal cancer with poor prognosis. The molecular mechanism of gallbladder carcinogenesis is still not clear. Wnt signaling pathway is a highly conserved pathway that regulates proliferation, differentiation, migration, genetic stability, apoptosis, and stem cell renewal. β-catenin plays major role in Wnt signaling and aberrations in β-catenin has found to be involved in several cancers pathogenesis. This study was carried out to document the mutations of β-catenin gene in gallbladder cancer and to evaluate its possible role in gallbladder carcinogenesis.

METHODS

PCR-SSCP (Single Stranded Conformation Polymorphism) for ctnnb1 was performed in 50 patients each of gallbladder cancer, cholelithiasis and 50 healthy controls. Samples that showed variation in banding pattern were sequenced.

RESULTS

Variation in banding pattern was observed in 9 (18%) samples of GBC, 4 (8%) of cholelithiasis and 2 (4%) of control. Sequencing analysis showed 9 novel mutations of ctnnb1 in exon 3 in 18% of gallbladder cancer (χ2 = 5.778; p < 0.05). Six point mutations, 1 deletion and 1 insertion mutation were found in 9 cases of gallbladder cancer. All point mutations were mis-sense mutation that affected highly conserved serine or threonine region that is important for GSK-3β phosphorylation.

CONCLUSION

Findings of the study suggests that high frequency of non synonymous mutations of β-catenin gene (ctnnb1) occurs in patients with gallbladder cancer. As these mutations mainly effect GSK 3β phosphorylation, it may be concluded that this might be an important step in gallbladder carcinogenesis. These β-catenin mutations lead to Wnt pathway activation and appear to have a role in progression from inflammation to cancer in gallbladder.

Molecular pathogenesis of gallbladder cancer: An update

Gallbladder carcinoma (GBC) is the most aggressive gastrointestinal malignancy throughout the world, with wide geographical variance. It is the subtype of biliary tract malignancy that has the poorest prognosis and lower survival among all biliary tract malignancies. Various factors are associated with GBC pathogenesis such as environmental, microbial, metabolic and molecular. Chronic inflammation of gallbladder due to presence of gallstone or microbial infection (eg. Salmonella or H. pylori) results in sustained production of inflammatory mediators in the tissue microenvironment, which can cause genomic changes linked to carcinogenesis. Genetic alterations are one of the major factors, associated with aggressiveness and prognosis. Researches have been done to explore suitable biomarker for early diagnosis and identify altered molecular pathways to develop appropriate biomarkers for early diagnosis, therapy and predicting prognosis. Different agents for targeted therapy against actionable mutations of molecules like EGFR, VEGF, mTOR, HER2, PDL-1, PD-1, MET, PI3K, N-cadherin, VEGFR, MEK1 and MEK2 are being tried. Despite these advancements, there is dismal improvement in the survival of GBC patients. Genetic aberrations other than actionable mutations and epigenetic modification including aberrant expressions of micro-RNAs, are also being studied both as diagnostic biomarker and therapeutic targets. Complex pathogenesis of GBC still needs to be unfolded. In this review we focus on the molecular pathogenesis of GBC elucidated till date along with future directions that can be explored to achieve better management of GBC patients.

Regional differences in gallbladder cancer pathogenesis: Insights from a multi-institutional comparison of tumor mutations

BACKGROUND

Although rare in the United States, gallbladder cancer (GBCA) is a common cause of cancer death in some parts of the world. To investigate regional differences in pathogenesis and outcomes for GBCA, tumor mutations were analyzed from a sampling of specimens.

METHODS

Primary tumors from patients with GBCA who were treated in Chile, Japan, and the United States between 1999 and 2016 underwent targeted sequencing of known cancer-associated genes. Fisher exact and Kruskal-Wallis tests assessed differences in clinicopathologic and genetic factors. Kaplan-Meier methods evaluated differences in overall survival from the time of surgery between mutations.

RESULTS

A total of 81 patients were included. Japanese patients (11 patients) were older (median age, 72 years [range, 54-81 years]) compared with patients from Chile (21 patients; median age, 59 years [range, 32-73 years]) and the United States (49 patients; median age, 66 years [range, 46-87 years]) (P = .002) and had more well-differentiated tumors (46% vs 0% for Chile/United States; P < .001) and fewer gallstone-associated cancers (36% vs 67% for Chile and 69% for the United States; P = .13). Japanese patients had a median mutation burden of 6 (range, 1-23) compared with Chile (median mutation burden, 7 [range, 3-20]) and the United States (median mutation burden, 4 [range, 0-27]) (P = .006). Tumors from Japanese patients lacked AT-rich interaction domain 1A (ARID1A) and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) mutations, whereas Chilean tumors lacked Erb-B2 receptor tyrosine kinase 3 (ERBB3) and AT-rich interaction domain 2 (ARID2) mutations. SMAD family member 4 (SMAD4) was found to be mutated similarly across centers (38% in Chile, 36% in Japan, and 27% in the United States; P = .68) and was univariately associated with worse overall survival (median, 10 months vs 25 months; P = .039). At least one potentially actionable gene was found to be altered in 80% of tumors.

CONCLUSIONS

Differences in clinicopathologic variables suggest the possibility of distinct GBCA pathogenesis in Japanese patients, which may be supported by differences in mutation pattern. Among all centers, SMAD4 mutations were detected in approximately one-third of patients and may represent a converging factor associated with worse survival. The majority of patients carried mutations in actionable gene targets, which may inform the design of future trials.

Targeting phosphoinositide-3-kinase pathway in biliary tract cancers: A remedial route?

Biliary tract cancers (BTC) are aggressive tumours with a low survival rate. At the advent of the genomic era, various genetic mutations in cell signalling pathways have been incriminated in carcinogenesis. Genomic analysis studies have connected main components of the phosphoinositide-3-kinase (PI3K) signalling pathway to BTC. PI3K pathway playing a central role in cell signalling and being deregulated in various tumours has been studied as a target for chemotherapy. Novel compounds have also been identified in preclinical trials that specifically target the PI3K pathway in BTCs, but these studies have not accelerated to clinical use. These novel compounds can be examined in upcoming studies to validate them as potential therapeutic agents, as further research is required to combat the growing need for adjuvant chemotherapy to successfully battle this tumour type. Furthermore, these molecules could also be used along with gemcitabine, cisplatin and 5-fluorouracil to improve sensitivity of the tumour tissue to chemotherapy. This review focuses on the basics of PI3K signalling, genetic alterations of this pathway in BTCs and current advancement in targeting this pathway in BTCs. It emphasizes the need for gene-based drug screening in BTC. It may reveal various novel targets and drugs for amelioration of survival in patients with BTC and serve as a stepping stone for further research.

Genetic landscape of gallbladder cancer: Global overview

Gallbladder cancer (GBC) is a rare malignancy of biliary tract cancer (BTC), characterized by late presentation and poor prognosis. It exhibits wide geographical as well as ethnical variations. So, diverse epidemiology along with etiological factors have been discussed in the current article. Present review unravels the germ line polymorphisms contributing to GBC susceptibility through candidate gene approach and GWAS. GBC is enriched with multiple mutations consisting of both passenger and driver mutations. The identification of the hotspot driver mutations which are involved in the etiopathogenesis of this cancer is necessary, before targeted therapies could be implemented clinically. Thus, this review sheds lights on both traditional low throughput methods along with high throughput NGS used to determine somatic mutations in cancer. With the advent of GWAS and high throughput sequencing methods, it is possible to comprehend the mutational landscape of this enigmatic disease. This article is the first one to provide insights into the genetic heterogeneity of GBC along with somatic mutational data from Catalogue of Somatic Mutations in Cancer (COSMIC) database. In addition, management of tumor heterogeneity as a therapeutic challenge has been discussed. Future goals involve liquid biopsy based research for better clinical management of the disease. Therefore, research efforts involving discovery of non- invasive markers for early stage cancer detection along with novel therapies should be directed.

Genotyping and mRNA profiling reveal actionable molecular targets in biliary tract cancers

Biliary tract cancer (BTC) represents a heterogeneous disease with dismal outcome. Herein, we examined genotype and angiogenesis features in BTC. We applied genotyping (Sanger, qPCR, 101-gene panel NGS), mRNA relative quantification methods, and β-catenin immunohistochemistry in 84 FFPE BTC (55 gallbladder [GBC], 14 intrahepatic [ICC], 15 extrahepatic [ECC] carcinomas). We identified 541 mutations in 68 (81%) tumors. Top mutated genes were CTNNB1 (36%); PTEN (33%); TP53 (31%); PIK3R1 (29%); PIK3CA (13%); BRCA2 and KRAS (12%); BRCA1 (11%). Six GBCs were hypermutated [hm] displaying a distinct mutational pattern. Mutations in TP53 and PI3K, Wnt and RAS components were prevalent among non-hypermutated tumors. All hmGBCs carried mutations in BRCA2 and other homologous recombination repair (HRR) genes, in PD1, but not in CTNNB1 and KRAS. None of the pathogenic BRCA2 p.D2723G and BRCA1 p.Q563* and c.5266dupC was present at frequencies expected for germline mutations. We observed copy gains (>6 copies) in EGFR (9% of informative tumors), PRKAR1A (7%), PIK3CA (6%), ERBB2 (5%) and MET (4%). TP53 mutations were prevalent in GBC (P<0.001) and PRKAR1A copy gains in ICC (P=0.007). PTEN was frequently co-mutated with CTNNB1 (P<0.001). Unrelated to CTNNB1 mutations, nuclear β-catenin was detected in 45% of tumors, among them in 5/6 hmGBC. We observed strong mRNA expression correlation of the two neuropilins (NRP1 and NRP2) with each other (Spearman's rho 0.59) and with the endothelin receptor (NRP2 rho 0.66; NRP2 rho 0.51), and between VEGFA and its receptors (FLT1 rho 0.49; KDR rho 0.45). All PIK3CA mutated tumors expressed endothelin 1 mRNA (P=0.010). Most tumors expressing nuclear β-catenin were negative for VEGFC (P=0.009) and FLT4 (P=0.002) mRNA expression. In conclusion, we confirmed the presence of known genomic aberrations in BTC and different genotypes between BTC subsets. Novel findings are the coexistence of PI3K and WNT pathway gene alterations in BTC, their association with angiogenesis, and the hypermutated GBCs with HRR gene mutations, all of which may be considered for new treatment options in this difficult to treat disease.

Gallbladder cancer epidemiology, pathogenesis and molecular genetics: Recent update

Gallbladder cancer is a malignancy of biliary tract which is infrequent in developed countries but common in some specific geographical regions of developing countries. Late diagnosis and deprived prognosis are major problems for treatment of gallbladder carcinoma. The dramatic associations of this orphan cancer with various genetic and environmental factors are responsible for its poorly defined pathogenesis. An understanding to the relationship between epidemiology, molecular genetics and pathogenesis of gallbladder cancer can add new insights to its undetermined pathophysiology. Present review article provides a recent update regarding epidemiology, pathogenesis, and molecular genetics of gallbladder cancer. We systematically reviewed published literature on gallbladder cancer from online search engine PubMed (http://www.ncbi.nlm.nih.gov/pubmed). Various keywords used for retrieval of articles were Gallbladder, cancer Epidemiology, molecular genetics and bullion operators like AND, OR, NOT. Cross references were manually searched from various online search engines (http://www.ncbi.nlm.nih.gov/pubmed,https://scholar.google.co.in/, http://www.medline.com/home.jsp). Most of the articles published from 1982 to 2015 in peer reviewed journals have been included in this review.

Genetic alterations in Japanese extrahepatic biliary tract cancer

Biliary tract cancer (BTC) is one of the most devastating types of malignant neoplasms worldwide. However, the mechanisms underlying the development and progression of BTC remain unresolved. BTC includes extrahepatic bile duct carcinoma (EBDC), gallbladder carcinoma (GBC) and ampulla of Vater carcinoma (AVC), named according to the location of the tumor. Although genetic alterations of intrahepatic cholangiocarcinoma have been investigated, those of EBDC, GBC and AVC have not yet been fully understood. The present study analyzed somatic mutations of 50 cancer-associated genes in 27 Japanese BTC cells, including: 11 EBDC, 14 GBC and 2 AVC. Next-generation sequencing using an Ion AmpliSeq Cancer Panel identified a total of 44 somatic mutations across 14 cancer-associated genes. Among the 44 mutations, 42 were judged as pathological mutations. Frequent mutations were identified in tumor protein 53 (TP53) (14/27), SMAD family member 4 (SMAD4) (6/27), phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit α (PIK3CA) (6/27), and Kirsten rat sarcoma (KRAS) (6/27); no significant differences were identified between EBDC and GBC tissues. Notably, the frequency of the PIK3CA mutation was higher when compared with previous reports. This result may suggest that the activation of the PIK3CA-protein kinase B signaling pathway, in addition to the abrogation of p53, SMAD4 and RAS mitogen-activated protein kinase may have a crucial role in the carcinogenesis of Japanese BTC. These findings may be useful for the development of personalized therapies for BTC.

Prognostic Significance of HER-2 and p53 Expression in Gallbladder Carcinoma in North Indian Patients

BACKGROUND/OBJECTIVE

Proto-oncogenes (HER-2) and tumor suppressor genes (p53) are commonly deregulated in gallbladder cancer (GBC). Available literature discloses skewed data from endemic Asian countries, especially north India. This study evaluates the prognostic significance of HER-2 and p53 in GBC patients from two major hospitals.

METHODS

Sixty resectable tumor and control specimens were prospectively collected from December 2012 to January 2016. Immunohistochemical staining was done using monoclonal antibodies to semiquantitatively evaluate HER-2 and p53 protein expression. The criterion for HER-2 positivity was set at >30% tumor cells showing complete, membranous staining while p53 positivity was established at <50% tumor cells showing complete nuclear staining. Clinicopathological correlations were drawn with major clinical outcomes.

RESULTS

It was observed that 36.67% (22/60) tumor cases and 5% (3/60) control cases showed strong HER-2 overexpression significantly correlating with sex, T-stage, nodal spread and distant metastasis (p < 0.05), while 33.3% (20/60) positivity was observed for p53 in tumor cases and 1.7% (1/60) in control cases. Multivariate analysis showed HER-2 (p = 0.04; hazard ratio: 2.36; 95% confidence interval: 1.04-5.33) and p53 (p = 0.03; hazard ratio: 5.63; 95% confidence interval: 1.21-26.26) expression to be independent prognostic factors.

CONCLUSION

Our study thus suggests the plausible role of HER-2 and p53 expression in worse prognosis of GBC in a north Indian population.

TNF-alpha promotes lymphangiogenesis and lymphatic metastasis of gallbladder cancer through the ERK1/2/AP-1/VEGF-D pathway

Background

Tumor necrosis factor-alpha (TNF-α), a key player in cancer-related inflammation, was recently demonstrated to be involved in the lymphatic metastasis of gallbladder cancer (GBC). Vascular endothelial growth factor D (VEGF-D) is a key lymphangiogenic factor that is associated with lymphangiogenesis and lymph node metastasis in GBC. However, whether VEGF-D is involved in TNF-α-induced lymphatic metastasis of GBC remains undetermined.

Methods

The expression of VEGF-D in patient specimens was detected by immunohistochemistry and the relationship between VEGF-D in the tissue and TNF-α in the bile of the matching patients was analyzed. The VEGF-D mRNA and protein levels after treatment with exogenous TNF-α in NOZ, GBC-SD and SGC-996 cell lines were measured by real-time PCR and ELISA. The promoter activity and transcriptional regulation of VEGF-D were analyzed with the relative luciferase reporter assay, mutant constructs, electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation (ChIP) assay, RNA interference and Western blotting. Inhibitors of JNK, p38 MAPK and ERK1/2 were used to explore the upstream signaling effector of AP-1. We used lentiviral vector expressing a VEGF-D shRNA construct to knockdown VEGF-D gene in NOZ and GBC-SD cells. The role of the TNF-α-VEGF-D axis in the tube formation of human dermal lymphatic endothelial cells (HDLECs) was determined using a three-dimensional coculture system. The role of the TNF-α - VEGF-D axis in lymphangiogenesis and lymph node metastasis was studied via animal experiment.

Results

TNF-α levels in the bile of GBC patients were positively correlated with VEGF-D expression in the clinical specimens. TNF-α can upregulate the protein expression and promoter activity of VEGF-D through the ERK1/2 - AP-1 pathway. Moreover, TNF-α can promote tube formation of HDLECs, lymphangiogenesis and lymph node metastasis of GBC by upregulation of VEGF-D in vitro and in vivo.

Conclusion

Taken together, our data suggest that TNF-α can promote lymphangiogenesis and lymphatic metastasis of GBC through the ERK1/2/AP-1/VEGF-D pathway.

Targeted Therapy in Biliary Tract Cancers

OPINION STATEMENT

A paradigm shift towards molecular-based, personalized cancer therapeutics has occurred in recent years and a number of targeted drugs have emerged. Various targeted therapies like erlotinib, trastuzumab, and cetuximab have been approved in lung, breast, and colon cancers, respectively. Numerous clinical trials involving targeted drugs in biliary tract cancers are currently in progress, though none have been approved for this disease. Biliary tract cancers are divided into separate entities both anatomically and in terms of pathogenesis but are grouped together in most trials given their rarity. Combination chemotherapy involving cisplatin and gemcitabine is the current standard of care in the metastatic setting. In this review, we will discuss the various molecular pathways implicated in biliary tract cancers and potential therapeutic targets.

Gallbladder cancer in Chile: what have we learned?

PURPOSE OF REVIEW

Gallbladder cancer (GBC) should be considered an orphan disease in oncology and represent a unique carcinogenetic model. This review will analyse some of the current aspects of GBC.

RECENT FINDINGS

Chile has the highest incidence and mortality of GBC in the world. Most patients are diagnosed in advanced stages with few treatment options. During the last two decades, little progress has been made in early diagnosis and treatment. At the molecular level, recent access to next-generation sequencing and other techniques for detecting the mutations of multiple genes have made advances in this area.

SUMMARY

The use of therapies targeted according to the detection of specific molecular alterations is in the early stages of evaluation and could represent a significant advance in the treatment of a large number of patients from developing countries.

Gall bladder carcinoma: Aggressive malignancy with protean loco-regional and distant spread

The most common malignancy of biliary tract is gallbladder cancer (GBC) which is the third most common cancer in gastrointestinal tract. It is a lethal disease for most patients in spite of growing awareness and improved diagnostic techniques. GBC has a very poor prognosis and the 5 year survival rate is < 10%. Although etiology of the carcinoma of the gallbladder is still obscure, various factors have been implicated, cholelithiasis being the most frequent. The incidence of GBC worldwide is based on the gender, geography and ethnicity which suggest that both genetic and environmental factors can cause GBC. The major route of spread of gallbladder cancer (GC) is loco-regional rather than distant. It spreads by lymphatic, vascular, neural, intraperitoneal, and intraductal routes. Sonography is usually the most common imaging test to evaluate symptoms of biliary tract disease including suspected GC. With recent advances in imaging modalities like multi-detector computed tomography (CT) scanners, magnetic resonance imaging-positron emission tomography/CT diagnosis of gallbladder cancer has improved. Studies have also targeted molecular and genetic pathways. Treatment options have included extended and radical surgeries and adjuvant chemotherapy. This review article deals in detail with important aspects of carcinoma gallbladder and its manifestations and challenges. Role of various imaging modalities in characterization and accurate staging has been discussed. The loco-regional spread of this aggressive malignancy is dealt explicitly.

Targeting specific molecular pathways holds promise for advanced gallbladder cancer therapy

Gallbladder cancer is the most common and aggressive malignancy of the biliary tract. The complete surgical resection is the only potentially curative approach in early stage; however, most cases are diagnosed in advanced stages and the response to traditional chemotherapy and radiotherapy is extremely limited, with modest impact in overall survival. The recent progress in understanding the molecular alterations of gallbladder cancer has shown great promise for the development of more effective treatment strategies. This has mainly resulted from the identification of molecular alterations in relevant intracellular signaling pathways-Hedgehog, PI3K/AKT/mTOR, Notch, ErbB, MAPK and angiogenesis-which are potential tailored targets for gallbladder cancer patients. This review discusses the recent remarkable progress in understanding the molecular alterations that represent novel prognosis molecular markers and therapeutic targets for gallbladder cancer, which will provide opportunities for research and for developing innovative strategies that may enhance the benefit of conventional chemotherapy, or eventually modify the fatal natural history of this orphan disease.