Molecular patterns in salivary duct carcinoma identify prognostic subgroups.

Salivary duct carcinoma (SDCa) is a rare cancer with high rate of metastases and poor survival despite aggressive multimodality treatment. This study analyzes the genetic changes in SDCa, their impact on cancer pathways, and evaluates whether molecular patterns can identify subgroups with distinct clinical characteristics and outcome. Clinicopathologic details and tissue samples from 66 patients (48 males, 18 females) treated between 1995 and 2018 were obtained from multiple institutions. Androgen receptor (AR) was assessed by immunohistochemistry, and the Illumina TruSight 170 gene panel was used for DNA sequencing. Male gender, lympho-vascular invasion, lymph node metastasis, and smoking were significant predictors of disease-free survival. AR was present in 79%. Frequently encountered alterations were mutations in TP53 (51%), PIK3CA (32%) and HRAS (22%), as well as amplifications of CDK4/6 (22%), ERBB2 (21%), MYC (16%), and deletions of CDKN2A (13%). TP53 mutation and MYC amplifications were associated with decreased disease-free survival. Analysis of cancer pathways revealed that the PI3K pathway was most commonly affected. Alterations in the cell cycle pathway were associated with impaired disease-free survival (HR 2.6, P = 0.038). Three subgroups based on AR and ERBB2 status were identified, which featured distinct molecular patterns and outcome. Among AR positive SDCa, HRAS mutations were restricted to AR positive tumors without ERBB2 amplification and HRAS mutations featured high co-occurrence with PIK3CA alterations, which seems specific to SDCa. AR negative SDCa were associated with poor disease-free survival in multivariate analysis (HR 4.5, P = 0.010) and none of these tumors exhibited ERBB2 amplification or HRAS mutations. AR and ERBB2 status in SDCa thus classifies tumors with distinct molecular profiles relevant to future targeted therapy. Furthermore, clinical factors such as smoking and molecular features such as MYC amplification may serve as markers of poor prognosis of SDCa.

European and Asian contribution to the genetic diversity of mainland South American chickens.

Chickens (Gallus gallus domesticus) from the Americas have long been recognized as descendants of European chickens, transported by early Europeans since the fifteenth century. However, in recent years, a possible pre-Columbian introduction of chickens to South America by Polynesian seafarers has also been suggested. Here, we characterize the mitochondrial control region genetic diversity of modern chicken populations from South America and compare this to a worldwide dataset in order to investigate the potential maternal genetic origin of modern-day chicken populations in South America. The genetic analysis of newly generated chicken mitochondrial control region sequences from South America showed that the majority of chickens from the continent belong to mitochondrial haplogroup E. The rest belongs to haplogroups A, B and C, albeit at very low levels. Haplogroup D, a ubiquitous mitochondrial lineage in Island Southeast Asia and on Pacific Islands is not observed in continental South America. Modern-day mainland South American chickens are, therefore, closely allied with European and Asian chickens. Furthermore, we find high levels of genetic contributions from South Asian chickens to those in Europe and South America. Our findings demonstrate that modern-day genetic diversity of mainland South American chickens appear to have clear European and Asian contributions, and less so from Island Southeast Asia and the Pacific Islands. Furthermore, there is also some indication that South Asia has more genetic contribution to European chickens than any other Asian chicken populations.

Is high-risk cutaneous squamous cell carcinoma of the head and neck a suitable candidate for current targeted therapies?

OBJECTIVE: Cutaneous squamous cell carcinoma (cSCC) is the second most common malignancy, most frequently affecting the head and neck. Treatment often requires surgery and can have significant functional morbidity. Research into disease pathogenesis and second line medical management of cSCC is limited. We assess genetic mutations in high-risk, primary head and neck cutaneous squamous cell carcinomas (HNcSCC) that may hinder or be beneficial for use of targeted therapy in disease management. METHODS: Genetic alterations and variant allele frequencies (VAFs) were analysed using a clinically relevant 48 gene panel in 10 primary high-risk non-metastatic treatment-naïve HNcSCC to evaluate applicability of targeted therapeutics. Variants present at all VAFs were evaluated for pathogenicity. Somatic mutation patterns of individual tumours were analysed. RESULTS: High-risk HNcSCC showed a high proportion (82%) of C to T transitions in keeping with ultraviolet-mediated damage. There was significant intratumour genetic heterogeneity in this cohort (MATH scores 20-89) with the two patients <45 years of age showing highest intratumour heterogeneity. TP53 was altered at VAF >22% in all cases, and mutations with highest VAF were observed in tumour suppressor genes in 80%. 70% of cases demonstrated at least one mutation associated with treatment resistance (KIT S821F, KIT T670I, RAS mutations at codons 12 and 13). CONCLUSION: We demonstrate high proportion tumour suppressor loss of function mutations, high intratumour genetic heterogeneity, and presence of well recognised resistance mutations in treatment naïve primary HNcSCC. These factors pose challenges for successful utilisation of targeted therapies.

Analysis of clinically relevant somatic mutations in high-risk head and neck cutaneous squamous cell carcinoma.

Cutaneous squamous cell carcinoma is the second most prevalent malignancy, most frequently occurring in the head and neck (head and neck cutaneous squamous cell carcinoma). Treatment of locally advanced or metastatic disease is associated with functional morbidity and disfigurement. Underlying genetic mechanisms are poorly understood. Targeted sequencing of 48 clinically relevant genes was performed on DNA extracted from formalin-fixed and paraffin-embedded high-risk primary head and neck cutaneous squamous cell carcinomas that remained non-metastatic at minimum follow-up of 24 months. Associations of somatic mutations with clinicopathologic characteristics were evaluated and compared with those described in the literature for metastatic disease. Alterations in 44 cancer-associated genes were identified. TP53 was mutated in 100% of cases; APC, ATM, ERBB4, GNAQ, KIT, RB1 and ABL1 were altered in 60% of cases. FGFR2 mutations (40%) were exclusively seen in patients with perineural invasion. MLH1 mutations were exclusively seen in the two younger patients (<45 years). Lower incidences of NOTCH1 mutations were observed compared with that described in metastatic head and neck cutaneous squamous cell carcinoma in the literature. Somatic mutations susceptible to EGFR inhibitors, and other small molecular targeted therapeutics were seen in 60% of cases. This study provides insights into somatic mutations in non-metastatic, high-risk head and neck cutaneous squamous cell carcinoma and identifies potential therapeutic targets. Alterations in FGFR2 and NOTCH1 may have roles in local and distant disease progression.

Somatic mutations in salivary duct carcinoma and potential therapeutic targets.

BACKGROUND: Salivary duct carcinomas (SDCa) are rare highly aggressive malignancies. Most patients die from distant metastatic disease within three years of diagnosis. There are limited therapeutic options for disseminated disease. RESULTS: 11 cases showed androgen receptor expression and 6 cases showed HER2 amplification. 6 Somatic mutations with additional available targeted therapies were identified: EGFR (p.G721A: Gefitinib), PDGFRA (p.H845Y: Imatinib and Crenolanib), PIK3CA (p.H1047R: Everolimus), ERBB2 (p.V842I: Lapatinib), HRAS (p.Q61R: Selumetinib) and KIT (p.T670I: Sorafenib). Furthermore, alterations in PTEN, PIK3CA and HRAS that alter response to androgen deprivation therapy and HER2 inhibition were also seen. MATERIALS AND METHODS: Somatic mutation analysis was performed on DNA extracted from 15 archival cases of SDCa using the targeted Illumina TruSeq Amplicon Cancer Panel. Potential targetable genetic alterations were identified using extensive literature and international somatic mutation database (COSMIC, KEGG) search. Immunohistochemistry for androgen receptor and immunohistochemistry and fluorescent in situ hybridization for HER2 were also performed. CONCLUSIONS: SDCa show multiple somatic mutations, some that are amenable to pharmacologic manipulation and others that confer resistance to treatments currently under investigation. These findings emphasize the need to develop testing and treatment strategies for SDCa.

East African origins for Madagascan chickens as indicated by mitochondrial DNA.

The colonization of Madagascar by Austronesian-speaking people during AD 50-500 represents the most westerly point of the greatest diaspora in prehistory. A range of economically important plants and animals may have accompanied the Austronesians. Domestic chickens (Gallus gallus) are found in Madagascar, but it is unclear how they arrived there. Did they accompany the initial Austronesian-speaking populations that reached Madagascar via the Indian Ocean or were they late arrivals with Arabian and African sea-farers? To address this question, we investigated the mitochondrial DNA control region diversity of modern chickens sampled from around the Indian Ocean rim (Southeast Asia, South Asia, the Arabian Peninsula, East Africa and Madagascar). In contrast to the linguistic and human genetic evidence indicating dual African and Southeast Asian ancestry of the Malagasy people, we find that chickens in Madagascar only share a common ancestor with East Africa, which together are genetically closer to South Asian chickens than to those in Southeast Asia. This suggests that the earliest expansion of Austronesian-speaking people across the Indian Ocean did not successfully introduce chickens to Madagascar. Our results further demonstrate the complexity of the translocation history of introduced domesticates in Madagascar.

Australian and Pacific contributions to the genetic diversity of Norfolk Island feral chickens.

BACKGROUND: Norfolk Island has a population of feral chickens which could be the result of domestic stock introduced onto the island by British settlers in 1788. However, there is ongoing debate about their origins because multiple human arrivals to the island may have brought chickens with them. Here we investigate the genetic origins of these feral chickens by sequencing their mitochondrial control region. We infer their phylogenetic relationships using a large dataset of novel sequences from Australian mainland domestic chickens and published sequences from around the world. RESULTS: Eleven control region haplotypes were found among the Norfolk Island feral and Australian mainland domestic chickens. Six of the Norfolk Island haplotypes fall within haplogroup E, but given the worldwide distribution of this haplogroup, the putative European origin of these chickens requires further investigation. One haplotype common among Norfolk Island and Australian samples belonged to a subgroup of haplogroup D, which appears to be restricted to chickens from Indonesia, Vanuatu and Guam. CONCLUSIONS: Our data show that at least two mitochondrial DNA haplogroups (D and E) have contributed to the genetic make-up of Norfolk Island feral chickens. In addition, we have provided insights into the discrete geographical distribution and diversity of the chicken haplogroup D. In view of the worldwide interest in the characterisation of poultry resources, further assessment of chicken populations of Island Southeast Asia and the Pacific region is warranted.

Genetic divergence among marine and lagoon Atherina boyeri populations in Greece using mtDNA analysis.

Genetic differentiation and phylogenetic relationships among 15 Atherina boyeri populations from several marine and lagoon or lake sites in Greece were investigated using mtDNA analysis. PCR-RFLP analysis of 12s, 16s rRNA genes and D-loop revealed 23 haplotypes. All the lake or lagoon populations, as well as the Kymi and Kalymnos populations that originated from sites with lagoonlike environmental conditions, showed haplotypes 1-6, clearly distinguishable from the marine populations, which exhibited types 7-23. The genetic divergence values estimated between the lagoon and the marine populations ranged from 5.55 to 10.45%. The high genetic differentiation observed between these two types of populations is also highlighted by the dendrograms obtained using UPGMA and maximum parsimony methods.