Fredrik Persson

Recurrent fusion of MYB and NFIB transcription factor genes in carcinomas of the breast and head and neck

The transcription factor gene MYB was identified recently as an oncogene that is rearranged/duplicated in some human leukemias. Here we describe a new mechanism of activation of MYB in human cancer involving gene fusion. We show that the t(6;9)(q22–23;p23–24) translocation in adenoid cystic carcinomas (ACC) of the breast and head and neck consistently results in fusions encoding chimeric transcripts predominantly consisting of MYB exon 14 linked to the last coding exon(s) of NFIB. The minimal common part of MYB deleted as the result of fusion was exon 15 including the 3′-UTR, which contains several highly conserved target sites for miR-15a/16 and miR-150 microRNAs. These microRNAs recently were shown to regulate MYB expression negatively. We suggest that deletion of these target sites may disrupt repression of MYB leading to overexpression of MYB-NFIB transcripts and protein and to activation of critical MYB targets, including genes associated with apoptosis, cell cycle control, cell growth/angiogenesis, and cell adhesion. Forced overexpression of miR-15a/16 and miR-150 in primary fusion-positive ACC cells did not significantly alter the expression of MYB as compared with leukemic cells with MYB activation/duplication. Our data indicate that the MYB-NFIB fusion is a hallmark of ACC and that deregulation of the expression of MYB and its target genes is a key oncogenic event in the pathogenesis of ACC. Our findings also suggest that the gain-of-function activity resulting from the MYB-NFIB fusion is a candidate therapeutic target.

Clinically Significant Copy Number Alterations and Complex Rearrangements of MYB and NFIB in Head and Neck Adenoid Cystic Carcinoma

Adenoid cystic carcinoma (ACC) of the head and neck is a malignant tumor with poor long‐term prognosis. Besides the recently identified MYB–NFIB fusion oncogene generated by a t(6;9) translocation, little is known about other genetic alterations in ACC. Using high‐resolution, array‐based comparative genomic hybridization, and massively paired‐end sequencing, we explored genomic alterations in 40 frozen ACCs. Eighty‐six percent of the tumors expressed MYB–NFIB fusion transcripts and 97% overexpressed MYB mRNA, indicating that MYB activation is a hallmark of ACC. Thirty‐five recurrent copy number alterations (CNAs) were detected, including losses involving 12q, 6q, 9p, 11q, 14q, 1p, and 5q and gains involving 1q, 9p, and 22q. Grade III tumors had on average a significantly higher number of CNAs/tumor compared to Grade I and II tumors (P = 0.007). Losses of 1p, 6q, and 15q were associated with high‐grade tumors, whereas losses of 14q were exclusively seen in Grade I tumors. The t(6;9) rearrangements were associated with a complex pattern of breakpoints, deletions, insertions, inversions, and for 9p also gains. Analyses of fusion‐negative ACCs using high‐resolution arrays and massively paired‐end sequencing revealed that MYB may also be deregulated by other mechanisms in addition to gene fusion. Our studies also identified several down‐regulated candidate tumor suppressor genes (CTNNBIP1, CASP9, PRDM2, and SFN) in 1p36.33‐p35.3 that may be of clinical significance in high‐grade tumors. Further, studies of these and other potential target genes may lead to the identification of novel driver genes in ACC.

High‐resolution genomic profiling of adenomas and carcinomas of the salivary glands reveals amplification, rearrangement, and fusion of HMGA2

Carcinoma ex pleomorphic adenoma (Ca‐ex‐PA) is an epithelial malignancy developing within a benign salivary gland pleomorphic adenoma (PA). Here we have used genome‐wide, high‐resolution array‐CGH, and fluorescence in situ hybridization to identify genes amplified in double min chromosomes and homogeneously staining regions in PA and Ca‐ex‐PA and to identify additional genomic imbalances characteristic of these tumor types. Ten of the 16 tumors analyzed showed amplification/gain of a 30‐kb minimal common region, consisting of the 5′‐part of HMGA2 (encoding the three DNA‐binding domains). Coamplification of MDM2 was found in nine tumors. Five tumors had cryptic HMGA2‐WIF1 gene fusions with amplification of the fusion oncogene in four tumors. Expression analysis of eight amplified candidate genes in 12q revealed that tumors with amplification/rearrangement of HMGA2 and MDM2 had significantly higher expression levels when compared with tumors without amplification. Analysis of individual HMGA2 exons showed that the expression of exons 3–5 were substantially reduced when compared with exons 1–2 in 9 of 10 tumors with HMGA2 activation, indicating that gene fusions and rearrangements of HMGA2 are common in tumors with amplification. In addition, recurrent amplifications/gains of 1q11‐q32.1, 2p16.1‐p12, 8q12.1, 8q22‐24.1, and 20, and losses of 1p21.3‐p21.1, 5q23.2‐q31.2, 8p, 10q21.3, and 15q11.2 were identified. Collectively, our results identify HMGA2 and MDM2 as amplification targets in PA and Ca‐ex‐PA and suggest that amplification of 12q genes (in particular MDM2), deletions of 5q23.2‐q31.2, gains of 8q12.1 (PLAG1) and 8q22.1‐q24.1 (MYC), and amplification of ERBB2 may be of importance for malignant transformation of benign PA.

Diagnostic and therapeutic implications of new molecular biomarkers in salivary gland cancers.

Salivary gland carcinomas (SGCs) are uncommon tumors, constituting approximately 5% of all cancers of the head and neck. They are a heterogeneous group of diseases that pose significant diagnostic and therapeutic challenges. The treatment of patients with SGCs is mainly restricted to surgery and/or radiation therapy and there is only limited data available on the role of conventional systemic and targeted therapies in the management of patients with advanced disease. There is thus a great need to develop new molecular biomarkers to improve the diagnosis, prognostication, and therapeutic options for these patients. In this review, we will discuss the most recent developments in this field, with focus on pathognomonic gene fusions and other driver mutations of clinical significance. Comprehensive cytogenetic and molecular genetic analyses of SGCs have revealed a translocation-generated network of fusion oncogenes. The molecular targets of these fusions are transcription factors, transcriptional coactivators, and tyrosine kinase receptors. Prominent examples of clinically significant fusions are the MYB-NFIB fusion in adenoid cystic carcinoma and the CRTC1-MAML2 fusion in mucoepidermoid carcinoma. The fusions are key events in the molecular pathogenesis of these tumor types and contribute as new diagnostic, prognostic, and therapeutic biomarkers. Moreover, next-generation sequencing analysis of SGCs have revealed new druggable driver mutations, pinpointing alternative therapeutic options for subsets of patients. Continued molecular characterization of these fusions and their down-stream targets will ultimately lead to the identification of novel driver genes in SGCs and will form the basis for development of new therapeutic strategies for these patients.

Prognostic factors for survival after surgery for adrenal metastasis

AIM To better define the indications for adrenalectomy for adrenal metastasis we have analysed factors predicting survival in our institutional series. METHODS A consecutive series of 30 patients undergoing adrenalectomy for metastasis (1996-2007), excluding patients with simultaneous ipsilateral renal cell carcinoma (RCC), was studied. Metastases were regarded as synchronous (<6 mo), or metachronous (>6 mo), depending on the interval after primary surgery. Survival was calculated from time of adrenalectomy and factors influencing survival were identified. RESULTS The tumour diagnoses were RCC n = 9, malignant melanoma n = 5, non-small-cell lung cancer n = 5, colorectal carcinoma n = 4, foregut carcinoid n = 2, adrenocortical carcinoma, breast cancer, hepatocellular carcinoma, urothelial carcinoma, and liposarcoma (one each); nine adrenal metastases were synchronous and 21 metachronous. Ten patients had undergone previous surgery for extra-adrenal metastases. Out of 30 adrenalectomies 10 were laparoscopic (LAdx) and 20 open (OAdx) procedures without surgical complications. The local recurrence rate was low: LAdx 1/10, OAdx 1/20, and the median survival was 23 months. Independent prognosticators of favourable survival were adrenalectomy for potential cure (p = 0.01), no previous metastasis surgery (p = 0.02), and tumour type (p = 0.043), with better prognosis for patients with adrenal metastasis from colorectal carcinoma and RCC and worse prognosis in non-small-cell lung cancer and malignant melanoma. CONCLUSIONS Surgery for adrenal metastasis is safe and the indication for this procedure in an individual patient can be supported by several prognostic factors. The survival benefit in patients with adrenalectomy for potential cure indicates a therapeutic value of adrenalectomy in selected patients.

High-resolution array CGH analysis of salivary gland tumors reveals fusion and amplification of the FGFR1 and PLAG1 genes in ring chromosomes.

We have previously identified a subgroup of pleomorphic salivary gland adenomas with ring chromosomes of uncertain derivation. Here, we have used spectral karyotyping (SKY), fluorescence in situ hybridization (FISH) and high-resolution oligonucleotide array-CGH to determine the origin and content of these rings and to identify genes disrupted as a result of ring formation. Of 16 tumors with rings, 11 were derived from chromosome 8, 3 from chromosome 5 and 1 each from chromosomes 1, 6 and 9. Array-CGH revealed that 10/11 r(8) consisted of amplification of a 19 Mb pericentromeric segment with recurrent breakpoints in FGFR1 in 8p12 and in PLAG1 in 8q12.1. Molecular analyses revealed that ring formation consistently generated novel FGFR1–PLAG1 gene fusions in which the 5′-part of FGFR1 is linked to the coding sequence of PLAG1. An alternative mechanism of PLAG1 activation was found in tumors with copy number gain of an intact PLAG1 gene. Rings derived from chromosomes 1, 5, 6 or 9 did not result in gene fusions, but rather resulted in losses indicative of the involvement of putative tumor suppressor genes on 8p, 5p, 5q and/or 6q. Our findings also reveal a novel mechanism by which FGFR1 contributes to oncogenesis and further illustrate the versatility of the FGFR1 and PLAG1 genes in tumorigenesis.

Salivary gland cancer: an update on present and emerging therapies.

Malignant salivary gland tumors make up a small proportion of malignancies worldwide, yet vary widely in terms of histology, patterns of spread, and recurrence. A better understanding of this variability will guide appropriate treatment recommendations and lead to improved outcomes. Recent molecular genetic studies have uncovered a translocation-generated gene fusion network in salivary gland carcinomas that can be used for diagnosis, treatment decisions, and development of specific targeted therapies. The gene fusions encode novel fusion oncoproteins that function as transcriptional coactivators, tyrosine kinase receptors, and transcription factors involved in growth-factor signaling and cell-cycle regulation. While surgery currently is the primary therapy for operable tumors, radiation plays an important role in the postoperative setting, as well as in the definitive setting for inoperable lesions. An awareness of the risk factors for tumor recurrence and spread is important for both adjuvant therapy referrals and for radiation treatment planning purposes. Additionally, chemotherapy is being used increasingly in both the concurrent setting as a radiosensitizer, as well as in the palliative setting for metastatic tumors. Future trials investigating concurrent chemotherapy and radiation, as well as the use of targeted agents based on evolving molecular discoveries, will elucidate optimal personalized approaches for this challenging disease.

Studies of genomic imbalances and the MYB-NFIB gene fusion in polymorphous low-grade adenocarcinoma of the head and neck.

Polymorphous low-grade adenocarcinoma (PLGA) is a malignancy predominantly originating from the minor salivary glands. The molecular events underlying the pathogenesis of PLGA is poorly understood and no recurrent genetic aberrations have so far been identified. We used genome-wide, high-resolution aCGH analysis to explore genomic imbalances in 9 cases of PLGA. Because of the well-known morphologic similarities between PLGA and adenoid cystic carcinoma (ACC) we also analyzed all tumors for expression of the recently identified ACC-associated MYB-NFIB gene fusion. aCGH analysis revealed that the PLGA genome contains comparatively few copy number alterations (CNAs). Gains/losses of whole chromosomes or chromosome arms were more than twice as common as partial CNAs. Two cases showed gain of chromosome 8 and one case each gain of chromosome 9, loss of chromosome 22 and loss of the Y chromosome. One case showed loss of the entire 6q arm and one case an interstitial deletion of a 33-Mb segment within 6q22.1-q24.3. This region contains the MYB oncogene and the candidate tumor suppressor gene PLAGL1. RT-PCR analysis revealed that one of the 9 PLGAs expressed the ACC-associated MYB-NFIB gene fusion, illustrating the diagnostic difficulties associated with the diagnosis of these morphologically partly overlapping entities. Taken together, our findings indicate that the PLGA genome is genetically stable and contains comparatively few CNAs which is in line with the clinical observation that PLGA is a slow-growing, low-grade carcinoma with low metastatic potential.

Metachronous and synchronous occurrence of 5 primary malignancies in a female patient between 1997 and 2013 : A case report with germline and somatic genetic analysis

The number of patients with multiple primary malignancies has been increasing steadily in recent years. In the present study, we describe a unique case of an 81-year-old woman with 5 metachronous and synchronous primary malignant neoplasms. The patient was first diagnosed with an endometrium adenocarcinoma in 1997 and a colon adenocarcinoma in 2002. Eleven years after her colon surgery, in 2013, the patient presented with 3 other primary malignancies within a 4-month time span: an invasive malignant melanoma on the lower leg, an invasive mucinous breast carcinoma in the right breast, and a pleomorphic spindle cell sarcoma on the left upper arm. Subsequent routine medical checkups in 2013–2017 revealed no metastases of the primary malignancies. The patient mentioned a familial aggregation of malignant tumors, including 2 sisters with breast cancer and a brother with lung cancer. Interestingly, next-generation sequencing analysis of the patient’s blood sample detected no mutations in the BRCA1, BRCA2, TP53, PTEN, CDH1, PALB2, RAD51C, RAD51D, MLH1, MSH2, MSH6, PMS2, EPCAM, APC, MUTYH, STK11, BMPR1A, SMAD4, PTEN, POLE, POLD1, GREM1, and GALNT12 genes. Therefore, whole genome sequencing is warranted to identify cancer-related genetic alterations in this patient with quintuple primary malignancies.