Loss of heterozygosity and microsatellite alterations in p53 and RB genes in adenoid cystic carcinoma of the salivary glands

High-grade transformation of head and neck adenoid cystic carcinoma demonstrates distinctive clinicopathological features and an unfavorable prognosis: a matched case-control study of the largest series in China

PURPOSE

Amidst the rarity of High-grade transformation (HGT) in adenoid cystic carcinoma (ACC), this study offers unprecedented insights into its aggressive nature and clinical implications.

METHODS

A 1:1 match comparison between 23 HGT patients and non-HGT counterparts was extracted from 412 ACC cases, focusing on dissecting distinctive clinicopathological features and prognostic outcomes.

RESULTS

The predominant sites of HGT were the sinonasal and lacrimal glands (30.4% each). Notably, the solid subtype was the most prevalent pattern within HGT, accounting for 69.6% of cases. Compared to non-HGT, the HGT cohort exhibited significantly higher rates of lymph node metastasis (39.1% vs. 8.7%; P < 0.05), perineural invasion (60.9% vs. 26.1%; P < 0.05), and increased Ki-67 proliferation index (35.0% vs. 10.0%; P < 0.05). Moreover, HGT regions typically showed reduced or absent p63 expression, along with high-grade pathomorphology. HGT was associated with increased recurrence (55.0%) and distant metastasis (78.3%), leading to an average survival of 35.9 months and a 3-years mortality rate of 35.0%. Overall and progression-free survival rates were significantly decreased in the HGT group.

CONCLUSION

This study represents the largest single-center cohort of HGT cases to our knowledge, highlighting its frequent occurrence in the sinonasal and lacrimal glands and association with poorer outcomes. The findings support classifying HGT in ACC as Grade 4, reflecting its severity.

Prognostic Significance of Histopathological Parameters for Salivary Gland Adenoid Cystic Carcinoma

Adenoid cystic carcinoma (ACC) is a rare salivary gland tumor that accounts for approximately 1% of all head and neck cancers. Despite its initial indolent behavior, long-term survival is poor due to locoregional recurrence in approximately 40% and distant metastasis in up to 60% of patients who undergo radical treatment. The histological parameters of ACC and the combination of these parameters in histopathological grading systems provide valuable prognostic information about the clinical course of the disease. Within this context, this review aims to analyze the impact of histopathological parameters, individual or combined in histopathological grading systems of malignancy, on ACC prognosis. Individual histopathological parameters such as solid pattern, presence of tumor necrosis, high-grade transformation, dominance of the epithelial component, presence of perineural and lymphovascular invasion, and positive surgical margins have negative impacts on the survival of patients with ACC. There are currently four histopathological grading systems for ACC; however, few studies have validated these systems and most of them explored small cohorts with short follow-up. Considering that the application of grading systems has been associated with ACC prognosis, a broader validation will allow not only their use for prognostic prediction but also assist in treatment planning.

Selinexor for the treatment of recurrent or metastatic salivary gland tumors: Results from the GEMS-001 clinical trial

OBJECTIVES

We aimed to evaluate the activity of selinexor, an oral selective inhibitor of nuclear export, in patients with recurrent or metastatic salivary gland tumors (SGT).

METHODS

GEMS-001 is an open-label Phase 2 study for patients with recurrent or metastatic SGT with two parts. In Part 1 of the protocol, patients had tumor samples profiled with targeted next generation sequencing as well as immunohistochemistry for androgen receptor, HER-2 and ALK. For Part 2, patients with no targeted therapies available were eligible to receive selinexor 60 mg given twice weekly every 28 days. The primary endpoint was objective response rate. Secondary endpoints included progression-free survival (PFS) and prevalence of druggable alterations across SGT.

RESULTS

One hundred patients were enrolled in GEMS-001 and underwent genomic and immunohistochemistry profiling. A total of 21 patients who lacked available matched therapies were treated with selinexor. SGT subtypes (WHO classification) included adenoid cystic carcinoma (n = 10), salivary duct carcinoma (n = 3), acinic cell carcinoma (n = 2), myoepithelial carcinoma (n = 2), carcinoma ex pleomorphic adenoma (n = 2) and other (n = 2). Of 18 evaluable patients, stable disease (SD) was observed in 17 patients (94%) (SD ≥6 months in 7 patients (39%)). However, no objective responses were observed. The median PFS was 4.9 months (95% confidence interval, 3.4-10). The most common treatment-related Grade 1-2 adverse events were nausea [17 patients (81%)], fatigue [16 patients (76%)], and dysgeusia [12 patients (57%)]. Most common treatment-related Grade 3-4 adverse events were hyponatremia [3 patients (14%)], neutrophil count decrease [3 patients (14%)] and cataracts [2 patients (10%)]. No treatment-related deaths were observed.

CONCLUSIONS

Although tumor reduction was observed across participants, single agent selinexor anti-tumor activity was limited.

Shallow whole genome sequencing of adenoid cystic carcinomas of the salivary glands identifies specific chromosomal aberrations related to tumor progression

BACKGROUND AND PURPOSE

Adenoid cystic carcinomas (ACC) are characterized by high rate of local recurrence and late distant metastasis. Chromosomal changes in the evolution from primary tumors to metastatic disease of ACC have not been appointed. Here we investigated the chromosomal alterations of 53 primary tumors from ACC patients with different progressive states by shallow whole genome sequencing to identify potential new markers for metastatic spread.

METHODS

Illumina paired-end libraries were generated using DNA from the primary tumor of 53 ACC patients. Fragmented DNA was end-repaired, A-tailed and multiplex sequencing adapters were ligated. Sequence data were mapped to HG19 and a copy-number analysis was conducted using the QDNAseq R package (version 1.10.0). Outliers were removed and data was smoothed by applying the circular binary segmentation algorithm implemented in the R package copynumber version 1.22.0. A modified chromosomal instability (CNI) score was used to analyze deletions and amplifications.

RESULTS

Cluster analysis of the whole genome sequencing revealed that the frequency of chromosomal aberrations were increased in ACC with local recurrence and distant metastases in comparison to ACC patients with no metastatic spread. Specifically, chromosome 6 and 12 and exclusively the entire chromosome 4 showed an increased frequency of chromosomal alterations with tumor progression.

CONCLUSION

Our data show a molecular evolution from primary tumors to local recurrences and distant metastases and pinpoint the critical chromosomal regions involved in this process. These regions should be in the focus of the search for therapeutic targets of progressive ACC.

Particular aspects in the cytogenetics and molecular biology of salivary gland tumours - current review of reports

Salivary gland tumours are a group of lesions whose heterogeneity of biological and pathological features is widely reflected in the molecular aspect. This is demonstrated by an increasing number of studies in the field of genetics of these tumours.

The aim of this study was to collect the most significant scientific reports on the cytogenetic and molecular data concerning these tumours, which might facilitate the identification of potential biomarkers and therapeutic targets. The analysis covered 71 papers included in the PubMed database. We focused on the most common tumours, such as pleomorphic adenoma, Warthin tumour, mucoepidermoid carcinoma, and others. The aim of this study is to present current knowledge about widely explored genotypic alterations (such as PLAG1 gene in pleomorphic adenoma or MECT1 gene in mucoepidermoid carcinoma), and also about rare markers, like Mena or SOX10 protein, which might also be associated with tumourigenesis and carcinogenesis of these tumours.

Adenoid cystic carcinoma: current therapy and potential therapeutic advances based on genomic profiling

Adenoid cystic carcinoma (ACC) is a rare cancer with high potential for recurrence and metastasis. Efficacy of current treatment options, particularly for advanced disease, is very limited. Recent whole genome and exome sequencing has dramatically improved our understanding of ACC pathogenesis. A balanced translocation resulting in the MYB-NFIB fusion gene appears to be a fundamental signature of ACC. In addition, sequencing has identified a number of other driver genes mutated in downstream pathways common to other well-studied cancers. Overexpression of oncogenic proteins involved in cell growth, adhesion, cell cycle regulation, and angiogenesis are also present in ACC. Collectively, studies have identified genes and proteins for targeted, mechanism-based, therapies based on tumor phenotypes, as opposed to nonspecific cytotoxic agents. In addition, although few studies in ACC currently exist, immunotherapy may also hold promise. Better genetic understanding will enable treatment with novel targeted agents and initial exploration of immune-based therapies with the goal of improving outcomes for patients with ACC.

Histopathological grading of adenoid cystic carcinoma of the head and neck: analysis of currently used grading systems and proposal for a simplified grading scheme

BACKGROUND

Histopathological grading of adenoid cystic carcinoma (ACC) is a controversial issue. It is generally agreed that solid type ACC has a relatively poor prognosis. However, the amount of solid regions within this often mixed type tumor that predicts a poor prognosis is not firmly established. Some authors stipulate that the presence of a solid component regardless of the amount is a poor prognosticator where others argue that the amount should be taken into consideration. Two grading systems most commonly used are those described by Perzin et al./Szanto et al. and Spiro et al., respectively. They report that prognosis of ACC is poor if >30% and >50% of the tumor volume has a solid growth pattern, respectively.

MATERIAL AND METHODS

The described grading systems are applied to a series of 81 surgically treated cases of ACC at the VU University Medical Center, Amsterdam, The Netherlands. Moreover, we introduced an alternative grading system, in which the presence of a solid component, irrespective of its amount, is considered. All three systems of grading were tested for inter-observer concordance and prediction of prognosis.

RESULTS

Inter-observer concordance for grading ACC according to Perzin et al./Szanto et al. and Spiro et al., proved to be moderate with Kappa Scores of 0.393 and 0.433, respectively. Our alternative grading system yielded inter-observer concordance with a Cohen's kappa result of 0.990. All systems were comparable in discriminating patients with poor clinical outcome. Histopathological grade proved to be an independent prognosticator.

CONCLUSION

The presence of any solid component in ACC is a negative prognosticator, and can histopathologically be diagnosed with a high reliability. These results suggest to merely register the presence or absence of a solid tumor component since its inter-observer variability is very low, its reproducibility is high and its predictive value is comparable to the traditional grading systems used.

Salivary adenoid cystic carcinoma with an early phase of high-grade transformation: case report with an immunohistochemical analysis

BACKGROUND

The early phase of salivary gland carcinomas with high-grade transformation (HGT) is extremely rare. We reported one case of adenoid cystic carcinoma (AdCC) with early HGT, herein.

CASE PRESENTATION

The patient was a 27-year-old Japanese woman who suffered from swelling of the left parotid region. Most of this tumor consisted of typical AdCC histology, whereas the central area of this tumor was composed of solid growth component by atypical cells with clear cytoplasm and marked nuclear atypia. Immunohistochemically, this area was strongly and diffusely positive for epithelial membrane antigen, p53, p16, Her-2, cyclin A and cyclin B1. The Ki-67 labeling index of this area was high, entirely different from that of AdCC area.

CONCLUSION

Overall, this area was an early phase of AdCC-HGT. This case is the second case of early AdCC-HGT. We discuss the development of salivary gland carcinoma with HGT.

VIRTUAL SLIDES

http://www.diagnosticpatology.diagnomx.eu/vx/1598278104895730.

Increased expression of MDM2 and NM23 are associated with malignant transformation of pleomorphic adenoma

This study was designed to correlate the expression of both MDM2 and NM23 in pleomorphic adenoma (PA) to clinical background, histological features, local recurrence, and metastatic potentiality in this tumor. Expression of MDM2 and NM23 was studied immunohistochemically in 23 cases of PA. Our results demonstrated MDM2 and NM23 overexpression in almost all cases of PA. There was a significant difference of the MDM2 and NM23 mean values between benign PA and both carcinoma-ex PA and metastasizing PA. The results of this study show that the overexpression of NM23 and MDM2 oncoproteins could be used as reliable predictors of malignant progression as well as metastatic potentiality of PA.

Reappraisal of KIT mutation in adenoid cystic carcinomas of the salivary gland

BACKGROUND

While overexpression of KIT protein has been well documented in adenoid cystic carcinomas (ACCs), mutation of KIT gene has been a controversial issue. We wanted to evaluate clinical value of the KIT mutation and protein expression in ACC.

METHODS

We analyzed 33 cases of ACC. Gene mutations in KIT exons 9, 11, 13, and 17 were analyzed using paraffin-embedded tissue, and two different sets of primers with direct sequencing after polymerase chain reaction (PCR) for exon 9, 11, 13, and 17, and cloning of PCR products for exon 11. KIT protein expression was assessed by immunohistochemistry. The correlation between clinicopathological findings and these biomarkers was analyzed.

RESULTS

No KIT mutation was observed in all of the 33 cases. With one primer set, KIT mutation was found in nine of 33 cases (27.3%). However, these mutations were not reproducible in the experiment using another primer set. KIT protein overexpression was detected in 22 of 33 patients (66.7%). KIT protein expression was not statistically correlated with either clinicopathological factors or survival. Patients with metastasis showed a tendency of longer progression-free survival (P = 0.052) and overall survival (P = 0.080) when the tumor overexpressed KIT protein.

CONCLUSION

This study supports that mutational study using paraffin-embedded tissue should be interpreted with great caution. KIT gene mutation is very rare in ACC, and gene mutation is not the cause of protein overexpression. KIT protein expression may have a potential value for better prognostic factor in patients with metastasis.

Molecular biology of adenoid cystic carcinoma

BACKGROUND

Adenoid cystic carcinoma (ACC) is an unusual salivary gland malignancy that remains poorly understood. Standard treatment, including surgery with postoperative radiation therapy, has attained reasonable local control rates, but the propensity for distant metastases has limited any improvement in survival over time. Our understanding of the molecular mechanisms driving ACC is quite rudimentary, due to the infrequent nature of its occurrence.

METHODS

An extensive literature review was performed on salivary gland ACCs and basic science research findings.

RESULTS

This review highlights many findings that are emerging about the carcinogenesis of ACC including cytogenetics, tumor suppressor genes, oncogenes, epigenetic alterations, mitochondrial alterations, and biomarker studies.

CONCLUSION

Although there have been many discoveries, much still remains unknown about this rare malignancy. © 2011 Wiley Periodicals, Inc. Head Neck, 2011.

Adenoid cystic carcinoma: a rare clinical entity and literature review

The adenoid cystic carcinoma is a relatively rare epithelial tumor of the major and minor salivary glands, accounting for about 1% of all malignant tumor of the oral and maxillofacial region. Although it presents a widespread age distribution, peak incidence occurs predominantly among women, between the 5th and 6th decades of life. The clinical and pathological findings typical of this tumor include slow growth, perineural invasion, potential local recurrence and distant metastasis. Histopathologically it is composed of basaloid cells with primarily myoepithelial/basal cell differentiation. It presents three patterns, cribriform, tubular and solid; the solid type is related to a poor prognosis contrary to the cribriform type, which has a better prognosis. Surgical excision with wide margins is the treatment of choice, if it metastasizes to lymph nodules, post surgical radiotherapy is recommended. We presented herein the case of a 45 year old female patient who presented a palatal lesion, which was treated with surgery and radiotherapy as an additional treatment. We also described a brief literature review of adenoid cystic carcinoma.

Deletion of 1p32-p36 is the most frequent genetic change and poor prognostic marker in adenoid cystic carcinoma of the salivary glands

PURPOSE

Adenoid cystic carcinoma (ACC) is a relatively uncommon salivary gland malignancy known for its protean phenotypic features and pernicious clinical behavior. Currently, no effective therapy is available for patients with advanced nonresectable, recurrent, and/or metastatic disease. The purpose of this study is to identify prognostic factors other than tumor stage that can be used to predict the outcome of the patients with ACC.

EXPERIMENTAL DESIGN

We used comparative genomic hybridization (CGH) to identify copy number aberrations in 53 primary ACCs. Array CGH and fluorescence in situ hybridization analysis was used to validate CGH results on selected cases. We correlated these copy number aberrations with clinicopathologic factors using Pearson's chi2 or by the two-tailed Fisher exact test. The disease-specific survival and disease-free intervals were generated by the Kaplan-Meier product limit method.

RESULTS

Chromosomal losses (n = 134) were more frequent than gains (n = 74). The most frequent genetic change was the loss of 1p32-p36 in 44% of the cases followed by 6q23-q27, and 12q12-q14. The most frequently gained chromosomal regions were 8 and 18. Of the chromosomal aberrations, loss of 1p32-p36 was the only abnormality significantly associated with patient's outcome.

CONCLUSIONS

This study, for the first time, identifies loss of 1p32-p36 as a significant aberration in ACC. Molecular characterization of 1p32-36 region using the available genomic technologies may lead to the identification of new genes critical to the development of novel therapeutic targets for this disease copy number aberration.

Aberrant methylation in promoter regions of cyclin-dependent kinase inhibitor genes in adenoid cystic carcinoma of the salivary gland

Adenoid cystic carcinoma (ACC) is a common malignant neoplasm of the salivary gland. The mechanism underlying ACC carcinogenesis is not fully elucidated, although data on associated genetic alterations are accumulating. Cyclin-dependent kinase inhibitors (CKIs) act as tumor suppressors in various cancers, and aberrant methylation in the CKI gene promoter region has been linked to gene silencing and downregulation of expression. The present study investigated methylation of CKI genes, p15, p18, p19, p21, and p27, in 34 cases of ACC. We found frequent and plural methylations of these genes in most cases (68.8% in p15, 90.3% in p18, 78.8% in p19, 92.3% in p21, and 26.5% in p27). Cell cycle disruption induced by these epigenetic aberrations might be important in the tumorigenesis of ACC.

DNA copy number gains at loci of growth factors and their receptors in salivary gland adenoid cystic carcinoma

PURPOSE

Adenoid cystic carcinoma (ACC) is a malignant salivary gland tumor with a high mortality rate due to late, distant metastases. This study aimed at unraveling common genetic abnormalities associated with ACC. Additionally, chromosomal changes were correlated with patient characteristics and survival.

EXPERIMENTAL DESIGN

Microarray-based comparative genomic hybridization was done to a series of 18 paraffin-embedded primary ACCs using a genome-wide scanning BAC array.

RESULTS

A total of 238 aberrations were detected, representing more gains than losses (205 versus 33, respectively). Most frequent gains (>60%) were observed at 9q33.3-q34.3, 11q13.3, 11q23.3, 19p13.3-p13.11, 19q12-q13.43, 21q22.3, and 22q13.33. These loci harbor numerous growth factor [fibroblast growth factor (FGF) and platelet-derived growth factor (PDGF)] and growth factors receptor (FGFR3 and PDGFRbeta) genes. Gains at the FGF(R) regions occurred significantly more frequently in the recurred/metastasized ACCs compared with indolent ACCs. Furthermore, patients with 17 or more chromosomal aberrations had a significantly less favorable outcome than patients with fewer chromosomal aberrations (log-rank = 5.2; P = 0.02).

CONCLUSIONS

Frequent DNA copy number gains at loci of growth factors and their receptors suggest their involvement in ACC initiation and progression. Additionally, the presence of FGFR3 and PDGFRbeta in increased chromosomal regions suggests a possible role for autocrine stimulation in ACC tumorigenesis.

Concurrent loss of heterozygosity and copy number analysis in adenoid cystic carcinoma by SNP genotyping arrays

Adenoid cystic carcinoma (ACC) is one of the most common malignancies to arise in the salivary glands, yet very little is known of the genetic alterations that are involved in the pathogenesis of this disease. To further examine the genetic changes that underlie ACC, we analyzed genomic DNA obtained from 22 primary ACC and two ACC-derived cell lines by high-density oligonucleotide single-nucleotide polymorphism genotyping arrays (Affymetrix GeneChip Human Mapping 100K Set). Allelotype calls were analyzed by the Haplotype Correction version of the Linkage Disequilibrium Hidden Markov Model to determine loss of heterozygosity using information derived only from tumor samples. Comparison of data obtained from matched tumor-normal samples suggested that only deletion calls of >3 Mb were reliable. Within these parameters, ACC samples revealed a mean of three deletions per tumor, and no consensus areas of deletion were observed across the majority of tumors. Similarly, copy number analysis of primary hybridization data revealed no consensus areas of gene amplification. This is in contrast to a much higher rate of genomic alterations detected in a cohort of squamous carcinomas analyzed by the same methods. Our data show that most ACC have predominantly stable genomes, which is consistent with the theory that telomere crisis does not play a significant role in early stages of ACC tumor progression. Our data suggest that gene mutation and/or epigenetic events that cannot be detected by assay of gross alteration of chromosomal structure are likely to underlie the malignant transformation events of this tumor type.

Phenotypic features with p53 alterations related to human papillomavirus and prognostic evaluation in cervical cancer

Cervical cancer is one of the most common tumor affecting women worldwide. Human papillomavirus (HPV) was found to have a causal relationship with cervical cancer and its precursors. The interaction between HPV E6 protein and p53 was identified in in vitro studies. The aim of the study was to evaluate the prevalence of p53 alterations related to HPV infection and the prognostic significance of p53 alterations in cervical cancer. Studies were identified by a MEDLINE search, and all relevant articles were retrieved from 1991 to March 2004. The prevalence of p53 mutations is a rare event in cervical cancer. The correlation between p53 mutations and HPV or prognosis is controversial. Loss of heterozygosity (LOH) of p53 is more commonly found in cervical cancer and is related with the prognosis of this disease. There is no significant correlation between p53 polymorphism and development of cervical cancer. The p53 mutations were not commonly found in cervical cancer. LOH of p53 may contribute to the progression of this malignancy. p53 polymorphism failed to be an independent prognostic factor in predicting the outcome of patients with cervical cancer. Further, epidemiologic surveys should be undertaken in larger populations and in different geographical regions.

Adenoid cystic carcinoma of the maxillary sinus with gradual histologic transformation to high-grade adenocarcinoma: a comparative report with dedifferentiated carcinoma

We report a unique case of adenoid cystic carcinoma (ACC) of the maxillary sinus, with gradual histologic transformation from lower-grade ACC (cribriform and tubular types) to high-grade adenocarcinoma (HGA) showing a sequential histologic spectrum via solid-type ACC. A 74-year-old man presented with swelling and mild pain of the right cheek. CT scan showed a mass measuring approximately 4 cm, with marked bone destruction in the right maxillary sinus. A surgically resected specimen revealed that the tumor was comprised of three different components: HGA and solid-type ACC in the central portion and lower-grade ACC in the periphery. The tumor was discriminated from a dedifferentiated carcinoma or hybrid tumor. Autopsy specimens also demonstrated both solid-type ACC and HGA components in the lung and spleen. Immunohistochemically, positive staining of p53 protein was detected on both solid-type ACC and HGA cells, but cyclin D1 and HER2/neu was only seen in HGA cells. Solid-type ACC cells were immunoreactive for CD117 (c-kit), but lower-grade ACC and HGA cells were negative. This case suggests that the overexpression of CD117, p53 protein, cyclin D1, and HER2/neu might be involved in the progression from lower-grade ACC to solid-type ACC and HGA.

TP53 mutations in salivary gland neoplasms

Many studies have demonstrated that loss of TP53 gene function has an important role in the genesis of many neoplasms, including salivary gland neoplasms. The purpose of this study was to examine the mutation profile of the TP53 gene in salivary gland neoplasms. Genomic DNA was extracted from paraffin-embedded tissues of pleomorphic adenoma, carcinoma in pleomorphic adenoma, mucoepidermoid carcinoma, adenoid cystic carcinoma and polymorphous low grade adenocarcinoma. Exons 5 to 8 of the TP53 gene were amplified by polymerase chain reaction (PCR) to perform single-stranded conformational polymorphism (SSCP) analysis. Band shifting was observed in exons 5, 6 and 8 in 9 out of 18 neoplasms. The results of this study suggest that mutations in TP53 gene are related to salivary gland neoplasms pathogenesis and that exons 5 and 8 are most frequently involved.

Factores pronósticos en el carcinoma adenoide quístico de glándulas salivares

OBJECTIVE

Adenoid cystic carcinoma (ACC) is a relatively rare tumor which is characterized by its long clinical history, with multiple recurrences and late distant metastasis. The aim of the present study is to show our experience in the management of this tumor and the relationship of different clinico-pathological parameters with its prognosis.

MATERIAL AND METHODS

A retrospective study was carried out between 1984 and 2004 in 28 patients with ACC of the salivary glands, analyzing the most outstanding clinico-pathological variables in this tumor related to the prognosis of the tumor and the survival.

RESULTS

The overall survival rates at 5, 10 and 15 years were 88%, 69% and 52% respectively. Ten (36%) patients presented local recurrence and 10 (36%) presented distant metastasis (four of which also have local recurrence). Although the differences were not statistically significant, the patients with solid histological subtype (p=0.17), with positive margins status (p=0.2), with perineural invasion (p=0.59), and those treated with surgery alone (p=0.19), presented a worse survival.

DISCUSSION/CONCLUSION

Our study confirms that the ACC is a tumor with a high tendency to local recurrence and development of distant metastasis, even long term, which means a close follow-up for life. Nevertheless, it also demonstrates that acceptable survival rates can be obtained with aggressive treatment.

Mutations in components of the Wnt signaling pathway in adenoid cystic carcinoma

The Wnt signaling pathway is essential for normal development and organogenesis. However, inappropriate activation of Wnt signaling, which results in the nuclear translocation of beta-catenin, is associated with the development of various types of neoplasm. In this study, we investigated possible mutations in the genes for components of this pathway, namely, CTNNB1 (the gene for beta-catenin), AXIN1, and APC, in adenoid cystic carcinoma, by PCR, analysis of single-strand conformational polymorphism, and sequencing. Among a total of 20 cases of adenoid cystic carcinoma, seven cases (35%) were associated with mutations in one or more of these three components. A mutation in CTNNB1 was detected in one case. Five cases, including the case with a mutation in CTNNB1, were associated with missense mutations in AXIN1. An aberration in the mutation cluster region of APC was detected in two cases. Mutations trended to be detected more frequently in adenoid cystic carcinoma with solid growth pattern than that with tubular and cribriform growth pattern. In the cases in which we detected mutations, it is possible that the presence of the abnormal products of the mutated genes resulted in the inappropriate activation of the Wnt signaling pathway to tumorigenesis and the growth of adenoid cystic carcinoma.

Frequent downregulation of 14-3-3 sigma protein and hypermethylation of 14-3-3 sigma gene in salivary gland adenoid cystic carcinoma

14-3-3 sigma:, a target gene of the p53 tumour suppressor protein, has been shown to regulate the cell cycle at the G2/M checkpoint. Recent studies have demonstrated that 14-3-3 sigma is downregulated by hypermethylation of the CpG island in several types of cancer. In this study, we investigated the expression and methylation status of 14-3-3 sigma in human salivary gland adenoid cystic carcinoma (ACC) and mucoepidermoid carcinoma (MEC). Immunohistochemical analysis revealed that the positive expression rate of 14-3-3 sigma in ACC (one out of 14) was markedly lower than that in MEC (ten out of 10). Since most of the ACCs carried the wild-type p53 protein, downregulation of 14-3-3 sigma in ACC may not be due to the dysfunction of p53 pathway. Microdissection-methylation-specific PCR revealed that frequent hypermethylation of the 14-3-3 sigma gene was observed in ACC when compared to that in MEC. In cultured-ACC cells, we confirmed the downregulation of 14-3-3 sigma via hemimethylation of the gene by sequencing analysis after sodium bisulphite treatment. Furthermore, re-expression of 14-3-3 sigma in the ACC cells was induced by the treatment with DNA demethylating agent, 5-aza-2'-deoxycytidine. Irradiation apparently induced the enhanced expression of 14-3-3 sigma and G2/M arrest in normal salivary gland cells; however, in the ACC cells, neither induction of 14-3-3 sigma nor G2/M arrest was induced by irradiation. These results suggest that downregulation of 14-3-3 sigma might play critical roles in the neoplastic development and radiosensitivity of ACC.

PCNA, Ki-67 and p53 expressions in submandibular salivary gland tumours

Salivary gland tumours are uncommon with a broad heterogeneity. The most common benign tumour is the pleomorphic adenoma, whereas mucoepidermoid carcinoma and adenoid cystic carcinoma predominate among the malignancies. Most salivary gland tumours occur in the parotid, and consequently clinical and biological data are normally derived from this site. This work describes the expressions of PCNA, Ki-67 and p53 in 15 pleomorphic adenomas, 15 mucoepidermoid carcinomas and 15 adenoid cystic carcinomas of the submandibular gland. Our results showed that all pleomorphic adenomas were negative for p53 and Ki-67 with 66.6% being positive for PCNA. Conversely, p53 was positive in 53% of the mucoepidermoid carcinomas and in 20% of the adenoid cystic carcinomas. Ki-67 was expressed in 47.7% of the mucoepidermoid carcinomas and 40% of the adenoid cystic carcinomas. All malignant tumours were positive for PCNA. These results indicate that the proliferative rate analysed with PCNA and Ki-67 and the expression of p53 in pleomorphic adenoma and adenoid cystic carcinoma of the submandibular gland were similar to those described in the parotid and minor salivary glands. However, mucoepidermoid carcinomas showed higher expression of these markers than those of other salivary glands. This work is the first describing the expression of these immunohistochemical markers exclusively in submandibular salivary gland tumours.

Immunohistochemical expression of retinoblastoma pathway proteins in normal salivary glands and in salivary gland tumours

The expression of G1-phase cell-cycle regulators is commonly deregulated in human malignancies. In the present study, we investigate components of the retinoblastoma (RB) pathway in normal salivary glands (NSG) and in salivary gland tumours (SGT). Samples of NSG, pleomorphic adenoma (PA), adenoid cystic carcinoma (ACC), mucoepidermoid carcinoma (MEC), epithelial-myoepithelial carcinoma (EMC), malignant myoepithelioma (MEM), carcinoma ex pleomorphic adenoma (CEPA), and polymorphous, low-grade adenocarcinoma (PLGA) were examined immunohistochemically using antibodies to cyclin D1, cyclin-dependent kinase 4 (CDK-4), retinoblastoma protein (pRb), CDK inhibitor p16 and transcription factor E2F-1. In normal salivary glands, cyclin D1 and cdk-4 were not expressed in any case while p16 was positively expressed. pRb was abundant and E2F-1 moderately expressed. In tumors, cdk-4 was overexpressed in half of the cases. Most tumour cases showed decreased pRb immunoexpression compared to normal salivary glands. In contrast, expression of p16 and E2F-1 increased. pRb expression was absent in three cases of PA, two of EMC and one of CEPA. One case of MEM and one of PLGA showed no E2F-1 expression. Statistical analyses revealed positive correlations between cyclin D1 and cdk-4, cyclin D1 and E2F-1, cdk-4 and E2F-1, and p16 and E2F-1. The benign and malignant tumours expressed retinoblastoma pathway proteins differently form the normal salivary gland. Our findings suggest that, pRb pathway deregulation in salivary gland neoplasms is unrelated to their biological behaviour.

Dedifferentiated malignant myoepithelioma of the parotid gland

Dedifferentiated salivary gland tumor is a rare, recently recognized tumor type. A case of dedifferentiated malignant myoepithelioma in a 59-year-old man who presented with a painful mass in the left preauricular region is reported. Histologically, two distinct neoplastic cell populations were observed in the same tumor mass. The first population was composed of solid nests of polygonal eosinophilic or glycogen-rich clear cells showing neoplastic myoepithelial immunocytological features, such as positivity for cytokeratins, vimentin, S-100 protein (S-100), alpha-smooth muscle actin (SMA) and glial fibrillary acidic protein (GFAP). A multinodular growth pattern, necrosis and occasional mitotic figures suggested malignancy. This population was diagnosed as low-grade malignant myoepithelioma. The second population infiltrated diffusely into the parotid gland and facial nerves. It consisted of polygonal or short spindle cells with obvious pleomorphism and atypical mitoses. The tumor cells were positive for vimentin and cytokeratins, and showed an accumulation of p53 and cyclin D1. S-100 protein, SMA and GFAP were negative. This population was regarded as undifferentiated carcinoma. A final diagnosis of dedifferentiated malignant myoepithelioma was made. This seems to be the first published case of dedifferentiation in malignant myoepithelioma. Because any tumor type can undergo dedifferentiation with accumulation of additional genetic changes, complete sampling should be the standard approach to all salivary gland tumors in order to avoid missing a dedifferentiation component.

Clonality of combined tumors

CONTEXT

Tumors with mixed morphologic patterns (combined tumors) are sometimes encountered, and questions often arise regarding the mechanism of molecular pathogenesis of each component and their relationships.

OBJECTIVE

To determine whether different components of combined tumors contain the same or different genetic alterations, thus providing evidence for their clonality.

MATERIALS AND METHODS

Six combined tumors with 2 components (in each case, both components showed epithelial differentiation morphologically) were studied by microdissecting tumor cells from each morphologic area followed by loss of heterozygosity analysis.

RESULTS

In 1 of the cases studied, the different morphologic areas contained different patterns of genetic alterations. In the remaining 5 cases, the different morphologic areas harbored identical genetic changes in the chromosome regions studied. The latter group, interestingly, included a colonic tumor with an area of tubulovillous adenoma and an area of neuroendocrine carcinoma, and 2 lung tumors with squamous carcinoma and small cell carcinoma components.

CONCLUSIONS

Our results suggest that in the majority of combined tumors, cells with different phenotypes share similar genotype and may arise from a single precursor cell. However, in a minority of these tumors, different areas may be derived from different precursor cells.

Novel DNA copy number losses in chromosome 12q12--q13 in adenoid cystic carcinoma

In order to find common genetic abnormalities that may identify loci of genes involved in the development of adenoid cystic carcinoma (ACC), we investigated DNA copy number changes in 24 of these tumors by comparative genomic hybridization (CGH). Our results indicate that unlike many carcinomas, ACCs have relatively few changes in DNA copy number overall. Twenty tumors had DNA copy number changes, which were mostly restricted to a few chromosomal arms. A frequent novel finding was the loss of DNA copy number in chromosome 12q (eight tumors, 33%) with the minimal common overlapping region at 12q12--q13. Deletion in this region has not been reported to be frequent in other types of cancer analyzed by CGH. In addition, deletions in 6q23-qter and 13q21--q22 and gains of chromosome 19 were observed in 25% to 38% of ACCs. Deletion of 19q, previously reported in a small series of ACC, was not identified in the current group of carcinomas. The current CGH results for chromosomes 12 and 19 were confirmed by microsatellite allelotyping. These results indicate that DNA copy number losses in 12q may be important in the oncogenesis of ACC and suggest that the 12q12--q13 region may harbor a new tumor-suppressor gene.

ras gene mutations in salivary gland tumors

OBJECTIVE

To assess the prevalence of activating mutations in K-ras and H-ras genes in salivary gland tumors with ductal or acinar differentiation and to evaluate their potential correlation with clinical parameters.

DESIGN

Paraffin-embedded tissue samples of salivary gland carcinomas were investigated by the application of a direct sequence analysis procedure with automated DNA sequencing of polymerase chain reaction-amplified ras sequences.

SETTING

Tertiary care teaching hospital.

PATIENTS

Twenty-four patients with salivary gland carcinoma were surgically treated. Nine had adenocarcinoma, 1 had adenosquamous carcinoma, 11 had mucoepidermoid carcinoma, and 3 had acinic cell carcinoma.

RESULTS

Point mutations were detected in 7 (29%) of the 24 carcinomas examined. The K-ras gene was mutated in only 2 samples (8%): a GGC-to-ATC mutation at codon 13 in an adenocarcinoma and a GGC-to-GTC transversion mutation at codon 13 in a mucoepidermoid carcinoma. Five (21%) harbored H-ras mutations: 4 contained a GGC-to-GTC transversion mutation at codon 12 and 1 had 2 distinct mutations, the same G-to-T at codon 12 as was shown in the other cases and a GGT-to-GGA heterozygous mutation at codon 13. All the H-ras mutations were in the group of mucoepidermoid carcinoma lesions (45%; 5/11).

CONCLUSION

Our data suggest that K-ras gene alteration is probably not an important factor in the oncogenesis of human salivary gland tumors. However, mutational activation of the H-ras gene appears to play a role in the development and/or progression of salivary gland mucoepidermoid carcinomas.

H-ras gene mutations in salivary gland mucoepidermoid carcinomas

BACKGROUND

The authors' recent investigation of salivary gland tumors in ras gene alteration has suggested that K-ras activation may not play a role in their oncogenesis but H-ras may, especially in mucoepidermoid carcinomas. A study was undertaken to assess the overall incidence of mutated H-ras genes in mucoepidermoid carcinomas and to discover its potential correlation with clinicopathologic parameters.

METHODS

Fifty samples from patients with salivary gland mucoepidermoid carcinoma were analyzed for point mutations at codons 12, 13, and 61 of the H-ras gene using the polymerase chain reaction followed by automated direct sequencing methodology.

RESULTS

Mutated H-ras genes were detected in 9 patients, for an overall incidence of 18% (9 of 50 patients). All but 1 of the mutations occurred at codon 12: a GGC-to-GTC transversion in 8 patients and a GGC-to-GAC transition in 1 patient, resulting in the amino acid substitution of valine and aspartic acid, respectively, for glycine. One of the samples showed concurrent mutations at codons 12 (GGC-to-GTC) and 13 (GGT-to-GGA). None of the samples demonstrated mutations involving codon 61. The H-ras mutations were observed in 5% (1of 21), 17% (2 of 12), and 35% (6 of 17) of low, intermediate, and high grade lesions, respectively.

CONCLUSIONS

These data suggest involvement of H-ras activation in conjunction with other yet-unknown events in the development and/or progression of mucoepidermoid carcinomas. It is noteworthy that a stepwise increase in the frequency of H-ras mutations strongly correlates with tumor grade (P = 0.017). Molecular analysis of this gene alteration may provide assistance in the determination of tumor grade and differentiation.

Analysis of chromosome 9p21 deletion and p16 gene mutation in salivary gland carcinomas

The chromosomal locus 9p21 contains the p16(INK4a/CDKN2/MTS1) tumor suppressor gene that has been implicated in a variety of tumor types, including carcinomas of the head and neck, esophagus, and pancreas. To determine whether the loss of this gene is involved in salivary gland cancers, 35 carcinomas and paired nonneoplastic specimens were analyzed for loss of heterozygosity (LOH) of polymorphic genetic markers located in the region of interest. Five types of salivary gland tumors were studied: mucoepidermoid carcinoma, salivary duct carcinoma, adenoid cystic carcinoma, acinic cell carcinoma, and polymorphous low-grade adenocarcinoma. Seven of 9 salivary duct carcinomas showed LOH of 1 or more polymorphic markers. In 1 case of salivary duct carcinoma with LOH, we confirmed a deletion of bp 240-254 within exon 2. In addition, another salivary duct carcinoma showed a homozygous deletion of p16 in differential polymerase chain reaction analysis. Loss of heterozygosity was found in 1 of 10 adenoid cystic carcinomas and 1 of 8 mucoepidermoid carcinomas and was absent in the remaining subtypes. No mutations in exon 1 or exon 2 or homozygous deletion of p16 were found in these 2 particular neoplasms with LOH. These results suggest that inactivation of p16 is important in the development or progression of at least some salivary duct carcinomas, but we found no evidence that its alteration plays a role in the other subtypes examined.

Dedifferentiation in adenoid cystic carcinoma of salivary gland: an uncommon complication associated with an accelerated clinical course

Adenoid cystic carcinoma (ACC) of the salivary gland is generally an indolent tumor that pursues a protracted clinical course with recurrences and late metastasis. The authors report three cases of ACC with dedifferentiation to high-grade malignant neoplasms. One patient developed dedifferentiated ACC ab initio, with extensive local disease and multiple lymph nodes metastases at first presentation, requiring mutilating surgery. Two patients had dedifferentiated ACC 4 and 10 years, respectively, following excision of the initial uncomplicated ACC; both patients died within 1.5 years after recurrence. Histologically, the dedifferentiated component appeared as a distinct population of anaplastic cells with more abundant cytoplasm, irregular-shaped tumor islands infiltrating a desmoplastic stroma, and total loss of bicellular differentiation characteristic of ACC. The immunophenotypic profile was altered in comparison with the ACC, such as acquisition of strong staining for S100 protein and lack of a myoepithelial component in the two cases that were interpreted as being poorly differentiated adenocarcinoma. One case was a sarcomatoid neoplasm with focal myoepithelial features. Overexpression of p53 protein was demonstrated in the dedifferentiated component in one case, and overexpression of cyclin D1 was seen in two cases. The dedifferentiated component had a higher Ki67 index than did the ACC. To the authors' best knowledge, this report represents the first documentation of dedifferentiation as a form of tumor progression in ACC, which is associated with a sinister clinical outcome.

Genetic alterations in acinic cell carcinoma of the parotid gland determined by microsatellite analysis

We investigated, for the first time, the genetic alterations at certain chromosomal loci in 25 primary parotid acinic cell carcinomas to define the most frequently altered chromosomal regions and their association with pathologic features and DNA content analysis. Our results showed that 21 (84.0%) of the tumors had alteration in at least one of the loci tested. In general, chromosomal regions at chromosomes 4p, 5q, 6p, and 17p were more frequently altered than those on chromosomes 1p and 1q, 4q, 5p, and 6q. Certain markers at 4p15-16, 6p25-qter, and 17p11 regions showed the highest incidence of LOH, suggesting the presence of tumor suppressor genes associated with the oncogenesis of these tumors. LOH was significantly associated only with tumor grade. No apparent correlation between LOH and other clinicopathologic and DNA content characteristics was identified. Our study broadly defined the chromosomal arms and loci that may be targeted for further localization of the minimally deleted regions involved in the tumorigenesis of these tumors.

DNA analysis at p53 locus in adenoid cystic carcinoma: comparison of molecular study and p53 immunostaining

Abnormalities of the p53 tumor suppressor gene were investigated in 22 foci from 14 adenoid cystic carcinomas (ACC) by polymerase chain reaction (PCR)-based assays for dinucleotide (CA)n and pentanucleotide (AAAAT)n repeat polymorphisms and by immunohistochemical staining for oncoprotein expression. Adenoid cystic carcinomas were divided into lower grade (tubular and cribriform) subtypes and higher grade (trabecular and solid) subtypes. Histologically identified tumor cells were precisely microdissected from archival microslides and were used for molecular analysis. The overall frequency of p53 gene mutations detected by PCR-loss-of-heterozygosity (LOH) analysis was 57% and was higher than the frequency of over-expression of p53 oncoprotein detected by immunostaining (43%). In the molecular analysis of individual histological subtype foci, the number of foci with p53 gene mutation was significantly greater in the higher grade subtype foci than in the lower grade subtype foci and was greatest in solid-type foci (100%). In all six tumors in which histologically different foci were present in the same tumors, mutations of the p53 gene were detected. When tumor heterogeneity of the p53 gene was present among different histological foci in the same tumors, the mutations were always detected in the higher grade foci. When lower and higher grade foci were present in the same tumors, the identical mutations detected in the lower grade foci were present in the corresponding higher grade foci. These findings indicate that abnormalities of the p53 gene are involved in carcinogenesis and/or progression of this tumor and, furthermore, suggest that molecular analyses of ACC may provide information of prognostic importance.