Genomic landscape of a metastatic malignant proliferating tricholemmal tumor and its response to PI3K inhibition.

Proliferating tricholemmal tumors (PTTs) are rare benign neoplasms that arise from the outer sheath of a hair follicle. Occasionally, these PTTs undergo malignant transformation to become malignant proliferating tricholemmal tumors (MPTTs). Little is known about the molecular alterations, malignant progression, and management of MPTTs. Here, we describe the case of a 58-year-old female that had a widely metastatic MPTT that harbored an activating PIK3CA mutation and was sensitive to the PI3K inhibitor, alpelisib (BYL719). We review the available literature on metastatic MPTT, detail the patient's course, and present a whole genome analysis of this rare tumor.

LIM-Only Protein 4 (LMO4) and LIM Domain Binding Protein 1 (LDB1) Promote Growth and Metastasis of Human Head and Neck Cancer (LMO4 and LDB1 in Head and Neck Cancer).

Squamous cell carcinoma of the head and neck (HNSCC) accounts for more than 300,000 deaths worldwide per year as a consequence of tumor cell invasion of adjacent structures or metastasis. LIM-only protein 4 (LMO4) and LIM-domain binding protein 1 (LDB1), two directly interacting transcriptional adaptors that have important roles in normal epithelial cell differentiation, have been associated with increased metastasis, decreased differentiation, and shortened survival in carcinoma of the breast. Here, we implicate two LDB1-binding proteins, single-stranded binding protein 2 (SSBP2) and 3 (SSBP3), in controlling LMO4 and LDB1 protein abundance in HNSCC and in regulating specific tumor cell functions in this disease. First, we found that the relative abundance of LMO4, LDB1, and the two SSBPs correlated very significantly in a panel of human HNSCC cell lines. Second, expression of these proteins in tumor primaries and lymph nodes involved by metastasis were concordant in 3 of 3 sets of tissue. Third, using a Matrigel invasion and organotypic reconstruct assay, CRISPR/Cas9-mediated deletion of LDB1 in the VU-SCC-1729 cell line, which is highly invasive of basement membrane and cellular monolayers, reduced tumor cell invasiveness and migration, as well as proliferation on tissue culture plastic. Finally, inactivation of the LDB1 gene in these cells decreased growth and vascularization of xenografted human tumor cells in vivo. These data show that LMO4, LDB1, and SSBP2 and/or SSBP3 regulate metastasis, proliferation, and angiogenesis in HNSCC and provide the first evidence that SSBPs control LMO4 and LDB1 protein abundance in a cancer context.

Viable biobanking of primary head and neck squamous cell carcinoma.

OBJECTIVES/HYPOTHESIS: To determine the feasibility of viable storage of head and neck squamous cell carcinoma (HNSCC) for regrowth of cells in culture. STUDY DESIGN: Laboratory-based translational study. METHODS: Methods for intermediate-term frozen storage of viable HNSCC were explored using small pieces of primary tumor and dissociated HNSCC cells after short-term culture. Viable cells after freezing were confirmed by adherence to tissue culture plates, cell morphology, and increased cell or colony density. Two cultures were immunostained for cytokeratin to confirm epithelial origin of viable cultured cells after freezing. RESULTS: Six primary HNSCCs (two oral cavity, three larynx, one oropharynx) and two HNSCCs that had been passaged through a xenograft (two oral cavity) were dissociated to single cells and grown in short-term cell culture for 0 to 12 passages. After short-term culture, cells were frozen for up to 8 months, thawed, and replated. Frozen cells derived from all tumors (six primary and two xenografts) were successfully replated with cultures lasting >7 days with seven of eight tumors presenting increased colony or cell density over 1 week of growth after freezing. In total, 15 of 15 tested samples derived from six primary and two xenografted HNSCCs were viable after freezing. CONCLUSIONS: In the current study, we show that biopreservation of primary or xenografted HNSCC using short-term cell culture is feasible. Initial short-term cell culture was required for successful storage and viability of frozen cells. These proof-of-principle studies, if more widely implemented, could improve preclinical testing of new therapies for HNSCC.

Human-in-mouse modeling of primary head and neck squamous cell carcinoma.

OBJECTIVES/HYPOTHESIS: To develop a reliable modeling system for head and neck squamous cell carcinoma (HNSCC). STUDY DESIGN: Laboratory-based translational study. METHODS: HNSCC tissue was obtained from patients at biopsy/resection, cultured, and implanted into mice. In vivo, tumor growth, and survival was monitored by bioluminescence imaging. Histology and immunohistochemistry (IHC) were used to confirm HNSCC and human origin. RESULTS: Short-term culture techniques were optimized allowing survival of primary HNSCC cells more than 7 days in 76% of tumors. The size of the tumor biopsy collected did not correlate with the success of short-term culture or xenograft establishment. Xenograft modeling was attempted in primary HNSCCs from 12 patients with a success rate of 92%. Immunostaining confirmed human origin of epithelial tumor cells within the modeled tumor. Bioluminescence and Ki67 IHC suggested tumor proliferation within the model. Luciferase expression was maintained for as long as 100 days in modeled tumors. CONCLUSIONS: The techniques developed for short-term primary tumor culture followed by xenograft modeling provide a low-cost and tractable model for evaluation of HNSCC response to standard and novel therapies. The high success rate of human-in-mouse tumor formation from primary HNSCC suggests that selection pressures for tumor growth in this model may be less than those observed for establishment of cell lines. Bioluminescent imaging provides a useful tool for evaluating tumor growth and could be expanded to measure response of the modeled tumor to therapy. This model could be adapted for xenograft modeled growth of other primary tumor types.