Background Our previous analysis of papillary thyroid carcinomas (PTC) from the Ukrainian-American cohort exposed to 131I from the Chernobyl accident found RET/PTC rearrangements and other driver mutations in 60% of tumors. Methods In this study, we analyzed the remaining, mutation-negative tumors using RNA-Seq and RT-PCR to identify novel chromosomal rearrangements and characterize their relationship with radiation dose. Results The ETV6-NTRK3 rearrangement was identified by RNA-Seq in a tumor from a patient who received a high 131I dose. Overall, it was detected in 9/62 (14.5%) of post-Chernobyl and in 3/151 (2%) of sporadic PTCs (p=0.019). The most common fusion type was between exon 4 of ETV6 and exon 14 of NTRK3. The ETV6-NTRK3 prevalence in post-Chernobyl PTCs was associated with increasing 131I dose, albeit at borderline significance (p=0.126). The group of rearrangement-positive PTCs (ETV6-NTRK3, RET/PTC, PAX8-PPARγ) was associated with significantly higher dose response compared to the group of PTCs with point mutations (BRAF, RAS) (p<0.001). In vitro exposure of human thyroid cells to 1 Gy of 131I and γ-radiation resulted in the formation of ETV6-NTRK3 with a rate of 7.9 × 10−6 and 3.0 ×10−6 cells, respectively. Conclusions We report here the occurrence of ETV6-NTRK3 rearrangements in thyroid cancer and show that this rearrangement is significantly more common in tumors associated with exposure to 131I and has a borderline significant dose response. Moreover, ETV6-NTRK3 can be directly induced in thyroid cells by ionizing radiation in vitro and therefore may represent a novel mechanism of radiation-induced carcinogenesis.

Background Childhood exposure to I-131 from the 1986 Chernobyl accident led to a sharp increase in papillary thyroid carcinoma (PTC) incidence in regions surrounding the reactor. Data concerning the association between genetic mutations in PTCs and individual radiation doses are limited. Methods We performed mutational analysis of 62 PTCs diagnosed in a Ukrainian cohort of patients who were <18 y.o. in 1986 and received 0.008-8.6 Gy of I-131 to the thyroid and explored associations between mutation types and I-131 dose and other characteristics. Results RET/PTC rearrangements were most common (35%), followed by BRAF (15%) and RAS (8%) point mutations. Two tumors carrying PAX8/PPARγ rearrangement were identified. We found a significant negative association with I-131 dose for BRAF and RAS point mutations and a significant concave association with I-131 dose, with an inflection point at 1.6 Gy and odds ratio 2.1, based on a linear-quadratic model for RET/PTC and PAX8/PPARγ rearrangements. The trends with dose were significantly different between tumors with point mutations and rearrangements. Compared to point mutations, rearrangements were associated with residence in the relatively iodine deficient Zhytomyr region, younger age at exposure or surgery, and male gender. Conclusions Our results provide the first demonstration of PAX8/PPARγ rearrangements in post-Chernobyl tumors and show different associations for point mutations and chromosomal rearrangements with I-131 dose and other factors. These data support the relationship between chromosomal rearrangements, but not point mutations, and I-131 exposure and point to a possible role of iodine deficiency in generation of RET/PTC rearrangements in these patients.

Indolent T-cell lymphoproliferative disorders of the gastrointestinal tract are rare clonal T-cell diseases that more commonly occur in the intestines and have a protracted clinical course. Different immunophenotypic subsets have been described, but the molecular pathogenesis and cell of origin of these lymphocytic proliferations is poorly understood. Hence, we performed targeted next-generation sequencing and comprehensive immunophenotypic analysis of 10 indolent T-cell lymphoproliferative disorders of the gastrointestinal tract, which comprised CD4+ (n=4), CD8+ (n=4), CD4+/CD8+ (n=1) and CD4-/CD8-(n=1) cases. Genetic alterations, including recurrent mutations and novel rearrangements, were identified in 8/10 (80%) lymphoproliferative disorders. The CD4+, CD4+/CD8+, and CD4-/CD8-cases harbored frequent alterations of the JAK-STAT pathway genes (5/6, 82%); STAT3 mutations (n=3), SOCS1 deletion (n=1) and STAT3-JAK2 rearrangement (n=1), and 4/6 (67%) had concomitant mutations in epigenetic modifier genes (TET2, DNMT3A, KMT2D). Conversely, 2/4 (50%) of the CD8+ cases exhibited structural alterations involving the 3' untranslated region of the IL2 gene. Longitudinal genetic analysis revealed stable mutational profiles in 4/5 (80%) cases and acquisition of mutations in one case were a harbinger of disease transformation. The CD4+ and CD4+/CD8+ lymphoproliferative disorders displayed heterogeneous Th1 (T-bet+), Th2 (GATA3+) or hybrid Th1/Th2 (T-bet+/GATA3+) profiles, while the majority of CD8+ disorders and the CD4-/CD8-disease showed a type-2 polarized (GATA3+) effector T-cell (Tc2) phenotype. Additionally, CD103 expression was noted in 2/4 CD8+ cases. Our findings provide insights into the pathogenetic bases of indolent T-cell lymphoproliferative disorders of the 4 gastrointestinal tract and confirm the heterogeneous nature of these diseases.Detection of shared and distinct genetic alterations of the JAK-STAT pathway in certain immunophenotypic subsets warrants further mechanistic studies to determine whether therapeutic targeting of this signaling cascade is efficacious for a proportion of patients with these recalcitrant diseases.

Epidermal Growth Factor Receptor (EGFR) is frequently over-expressed in head and neck squamous cell carcinoma (HNSCC) where aberrant signaling downstream of this receptor contributes to tumor growth. EGFR variant III (EGFRvIII) is the most commonly altered form of EGFR and contains a truncated ligand-binding domain. We previously reported that EGFRvIII is expressed in up to 40% of HNSCC tumors where it is associated with increased proliferation, tumor growth and chemoresistance to anti-tumor drugs including the EGFR targeting monoclonal antibody cetuximab. Cetuximab was FDA-approved in 2006 for HNSCC but has not been shown to prevent invasion or metastasis. The present study was undertaken to evaluate the mechanisms of EGFRvIII-mediated cell motility and invasion in HNSCC. We found that EGFRvIII induced HNSCC cell migration and invasion in conjunction with increased STAT3 activation, which was not abrogated by cetuximab treatment. Further investigation demonstrated that EGF-induced expression of the STAT3 target gene HIF1-α, was abolished by cetuximab in HNSCC cells expressing wild-type EGFR under hypoxic conditions, but not in EGFRvIII-expressing HNSCC cells. These results suggest that EGFRvIII mediates HNSCC cell migration and invasion via increased STAT3 activation and induction of HIF1-α, which contribute to cetuximab resistance in EGFRvIII-expressing HNSCC tumors.

Purpose: This study aimed to investigate the utility of honokiol, a naturally occurring compound, in the treatment of head and neck squamous cell carcinoma (HNSCC) as well as its ability to target the epidermal growth factor receptor (EGFR), a critical therapeutic target in HNSCC, and to enhance the effects of other EGFR-targeting therapies.Experimental Design: Human HNSCC cell lines and the xenograft animal model of HNSCC were used to test the effects of honokiol treatment.Results: Honokiol was found to inhibit growth in human HNSCC cell lines, with 50% effective concentration (EC 50 ) values ranging from 3.3 to 7.4 μmol/L, and to induce apoptosis, as shown through Annexin V staining. These effects were associated with inhibition of EGFR signaling, including downstream inhibition of mitogen-activated protein kinase, Akt, and signal transducer and activator of transcription 3 (STAT3), and expression of STAT3 target genes, Bcl-X L and cyclin D1. Furthermore, honokiol enhanced the growth inhibitory and anti-invasion activity of the EGFR-targeting agent erlotinib. Although HNSCC xenograft models did not show significant inhibition of in vivo tumor growth with honokiol treatment alone, the combination of honokiol plus cetuximab, a Food and Drug Administration-approved EGFR inhibitor for this malignancy, significantly enhanced growth inhibition. Finally, HNSCC cells rendered resistant to erlotinib retained sensitivity to the growth inhibitory effects of honokiol.Conclusions: These results suggest that honokiol may be an effective therapeutic agent in HNSCC, in which it can augment the effects of EGFR inhibitors and overcome drug resistance.

Treatment of human head and neck squamous cell carcinoma (HNSCC) cell lines with guggulsterone, a widely available, well-tolerated nutraceutical, demonstrated dose-dependent decreases in cell viability with EC(50)s ranging from 5 to 8 microM. Guggulsterone induced apoptosis and cell cycle arrest, inhibited invasion and enhanced the efficacy of erlotinib, cetuximab and cisplatin in HNSCC cell lines. Guggulsterone induced decreased expression of both phosphotyrosine and total signal transducer and activator of transcription (STAT)-3, which contributed to guggulsterone's growth inhibitory effect. Hypoxia-inducible factor (HIF)-1alpha was also decreased in response to guggulsterone treatment. In a xenograft model of HNSCC, guggulsterone treatment resulted in increased apoptosis and decreased expression of STAT3. In vivo treatment with a guggulsterone-containing natural product, Guggulipid, resulted in decreased rates of tumor growth and enhancement of cetuximab's activity. Our results suggest that guggulsterone-mediated inhibition of STAT3 and HIF-1alpha provide a biologic rationale for further clinical investigation of this compound in the treatment of HNSCC.

B cell lymphoma 6 (BCL6) is a transcriptional repressor critical for the development and maintenance of germinal centers (GCs), which are required for generation of an effective humoral immune response. Genomic aberrations of BCL6, including mutations and translocations that occur during the GC reaction, as well as alterations of genes that regulate BCL6 expression, lead to sustained activity of BCL6, which promotes the development of GC-derived lymphomas. Since many types of B cell non-Hodgkin lymphomas (B-NHL) arise from neoplastic transformation of GC B cells and a high proportion harbor genetic lesions that deregulate BCL6 expression, inhibition of BCL6 has emerged as an attractive therapeutic strategy for lymphomas. Areas covered: This review examines the rationale for and challenges in therapeutic targeting of BCL6 in lymphomas. We describe approaches that have been used and are currently being considered for inhibition of BCL6. Expert opinion: Several BCL6 inhibiting agents, including peptidomimetics, small molecules, and natural compounds, most of which target the BTB domain of the protein at the corepressor binding site, have been developed with demonstration of anti-lymphoma activity in preclinical models. Future clinical trials will be important to investigate the efficacy of targeting BCL6 in B-NHL (and other neoplasms), particularly in combination with other therapies.

EATL frequently evolves from RCD type II (RCD II) but can occur "de novo" in individuals with celiac disease. Recurrent activating mutations in members of the JAK/STAT pathway have been recently described in EATL and RCD II, which suggests deregulation of cytokine signaling to be an early event in lymphomagenesis. Intraepithelial T cells are presumed to be the cell of origin of EATL (and RCD II). Recent in vitro molecular and phenotypic analyses and in vivo murine studies, however, suggest an origin of RCD II from innate IELs (NK/T cell precursors), which could also be the cell of origin of RCD II-derived EATL. The immune microenvironment of the small intestinal mucosa in celiac disease fosters the development of EATL, often in a multistep pathway.