Integrated Genomic and Functional microRNA Analysis Identifies miR-30-5p as a Tumor Suppressor and Potential Therapeutic Nanomedicine in Head and Neck Cancer

PURPOSE

To identify deregulated and inhibitory miRNAs and generate novel mimics for replacement nanomedicine for head and neck squamous cell carcinomas (HNSCC).

EXPERIMENTAL DESIGN

We integrated miRNA and mRNA expression, copy number variation, and DNA methylation results from The Cancer Genome Atlas (TCGA), with a functional genome-wide screen.

RESULTS

We reveal that the miR-30 family is commonly repressed, and all 5 members sharing these seed sequence similarly inhibit HNSCC proliferation in vitro. We uncover a previously unrecognized inverse relationship with overexpression of a network of important predicted target mRNAs deregulated in HNSCC, that includes key molecules involved in proliferation (EGFR, MET, IGF1R, IRS1, E2F7), differentiation (WNT7B, FZD2), adhesion, and invasion (ITGA6, SERPINE1). Reexpression of the most differentially repressed family member, miR-30a-5p, suppressed this mRNA program, selected signaling proteins and pathways, and inhibited cell proliferation, migration, and invasion in vitro. Furthermore, a novel miR-30a-5p mimic formulated into a targeted nanomedicine significantly inhibited HNSCC xenograft tumor growth and target growth receptors EGFR and MET in vivo. Significantly decreased miR-30a/e family expression was related to DNA promoter hypermethylation and/or copy loss in TCGA data, and clinically with decreased disease-specific survival in a validation dataset. Strikingly, decreased miR-30e-5p distinguished oropharyngeal HNSCC with poor prognosis in TCGA (P = 0.002) and validation (P = 0.007) datasets, identifying a novel candidate biomarker and target for this HNSCC subset.

CONCLUSIONS

We identify the miR-30 family as an important regulator of signal networks and tumor suppressor in a subset of HNSCC patients, which may benefit from miRNA replacement nanomedicine therapy.

Abstract 185: MicroRNA-375 suppresses extracellular matrix degradation and invadopodial activity in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a highly invasive cancer having an association with locoregional recurrence and lymph node metastasis. We previously reported that patients with lower microRNA-375 (miR-375) tumor:normal expression levels showed significantly decreased disease-specific survival, increased locoregional recurrence and distant metastasis. We also previously described that HNSCC cells with increased miR-375 showed significantly diminished invasion in vitro. The ability of cancer cells to degrade extracellular matrix (ECM) through secreted and membrane-bound proteases allows local invasion into the surrounding stroma, as well as possible metastasis. Invadopodia are specialized actin-rich structures, which mediate ECM degradation. Our objective was to determine whether elevated miR-375 expression in HNSCC cells also affects invadopodia formation and activity.

For the evaluation of the matrix degradation properties of UMSCC1 and OSC19 cell lines, an invadopodial matrix degradation assay was used. Western blot analyses were conducted to measure the total protein levels of selected invadopodia-associated proteins. The tyrosine phosphorylation states of cortactin were evaluated by immunoprecipitation experiments. For the detection of levels of secreted proteases in the conditioned cell growth medium, Human Protease Arrays were used. Quantitative RT-PCR measurements were used to evaluate the mRNA expression levels of the commonly regulated proteases.

We observed that the HNSCC cell lines with elevated miR-375 expression showed significant reductions in ECM degradation. We further identified that HNSCC cells expressing increased miR-375 expression had significantly suppressed amounts of mature invadopodia, although the levels of invadopodium precursors were not significantly altered. We determined that increased miR-375 expression in the HNSCC cell lines did not reduce cellular levels of invadopodia components, such as Tks5, cortactin and fascin. We also did not observe significant alterations to the tyrosine phosphorylation states of cortactin in the HNSCC cell lines. However, we found that the HNSCC cells with higher miR-375 expression had significant reductions in the mRNA expression and secreted levels of specific proteases, including Kallikrein 6, Kallikrein 10, and MMP-9.

In summary, we have extended our understanding of the impact of miR-375 expression levels on HNSCC invasion. We demonstrated that increased miR-375 expression in HNSCC cells reduced ECM degradation and invadopodial activity. Our data suggest that reduced miR-375 expression in HNSCC patients can contribute to the invasive properties of head and neck cancer through increased invadopodial activity.

Citation Format: Lizandra Jimenez, Ved P. Sharma, John S. Condeelis, Thomas M. Harris, Thomas J. Ow, Michael B. Prystowsky, Geoffrey J. Childs, Jeffrey E. Segall. MicroRNA-375 suppresses extracellular matrix degradation and invadopodial activity in head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 185. doi:10.1158/1538-7445.AM2015-185

Proteomic analysis of oral cavity squamous cell carcinoma specimens identifies patient outcome-associated proteins

CONTEXT

Global proteomic analysis of oral cavity squamous cell carcinoma was performed to identify changes that reflect patient outcomes.

OBJECTIVES

To identify differentially expressed proteins associated with patient outcomes and to explore the use of imaging mass spectrometry as a clinical tool to identify clinically relevant proteins.

DESIGN

Two-dimensional separation of digested peptides generated from 43 specimens with high-resolution mass spectrometry identified proteins associated with disease-specific death, distant metastasis, and loco-regional recurrence. RNA expressions had been correlated to protein levels to test transcriptional regulation of clinically relevant proteins. Imaging mass spectrometry explored an alternative platform for assessing clinically relevant proteins that would complement surgical pathologic diagnosis.

RESULTS

Seventy-two peptide features were found to be associated with 3 patient outcomes: disease-specific death (9), distant metastasis (16), and loco-regional recurrence (39); 8 of them were associated with multiple outcomes. Functional ontology revealed major changes in cell adhesion and calcium binding. Thirteen RNAs showed strong correlation with their encoded proteins, implying transcriptional control. Reduction of DSP, PKP1, and TRIM29 was associated with significantly shorter time to onset of distant metastasis. Reduction of PKP1 and TRIM29 correlated with poorer disease-specific survival. Additionally, S100A8 and S100A9 reductions were verified for their association with poor prognosis using imaging mass spectrometry, a platform more adaptable for use with surgical pathology.

CONCLUSIONS

Using global proteomic analysis, we have identified proteins associated with clinical outcomes. The list of clinically relevant proteins observed will provide a means to develop clinical assays for prognosis and optimizing treatment selection.

Isolation, characterization, and expression of the gene encoding the late histone subtype H1-gamma of the sea urchin Strongylocentrotus purpuratus

We cloned and characterized the gene encoding H1-gamma, a late histone subtype of the sea urchin species Strongylocentrotus purpuratus. The predicted primary sequence of H1-gamma is 216 amino acids in length and has a net charge of +70, which is high for a somatic H1 histone. The H1-gamma gene appears to be a unique sequence gene that is not tightly linked to the core histone genes. The 770-base-pair transcribed region of the H1-gamma gene is bordered on the 5' side by two previously described H1-specific sequence elements and on the 3' side by a hairpin loop structure and CAGA box sequences. We detected 3,900 stored maternal H1-gamma mRNA transcripts per egg. The number of H1-gamma transcripts per embryo rises by 9.5 h postfertilization, but the maximum rate of accumulation (4,300 molecules per min per embryo) occurs in the late-blastula-stage embryo between 14 and 21 h after fertilization. The number of H1-gamma mRNA molecules peaks 21 h after fertilization when there are 2.0 X 10(6) molecules per embryo (a 500-fold increase) and then decreases over the next 3.25 h to 1.3 million molecules per embryo. Between 24 and 82 h after fertilization the number of H1-gamma transcripts declines steadily (210 molecules per min per embryo) to reach approximately 5.4 X 10(5) H1-gamma mRNAs by 82 h postfertilization. Surprisingly, the number of late H1 mRNA molecules per embryo is greater than the number of late H2B mRNA molecules beginning at the early gastrula stage of development.

Comparison of the late H1 histone genes of the sea urchins Lytechinus pictus and Strongelocentrotus purpuratus

We have isolated and sequenced a gene encoding a late H1 histone subtype from the sea urchin species L. pictus. The primary structure of the late H1 subtype encoded by this gene is 209 amino acids in length, and has a net positive charge of 67. This gene is present in a single copy per haploid genome and encodes an mRNA of 752 nucleotides. Late H1 transcripts are detected in the unfertilized egg and are most prevalent in gastrulating embryos. Comparison of 375 bp of 5' flanking sequences of the L. pictus late H1 gene and the H1-gamma gene of a distantly related sea urchin species, S. purpuratus, reveals large blocks of sequences that are identical between the two genes. To determine if these conserved 5' sequences are present in other members of the sea urchin H1 gene family, the analogous region of S. purpuratus H1-alpha, an early H1 gene, was sequenced. The homology between the flanking sequences of the early and late families was limited to consensus sequences which are found upstream of all H1 genes. The possible regulatory implications of these findings are discussed.

Temporal expression of late histone messenger RNA in the sea urchin Lytechinus pictus

Sea urchin histones are encoded by several multigene families. The temporal expression of one of these families, the late histones, has been studied during the early development of Lytechinus pictus. Using a nuclease S1 assay, we detected about 10,000 transcripts encoding both late H3 and H4 proteins in the unfertilized egg. This suggests that the late genes were active at some point during oogenesis. The number of late gene transcripts begins to increase 6.5 hr after fertilization (64-cell stage), indicating that these genes probably become reactivated 4.5-6.5 hr after fertilization. The maximum rate of accumulation of transcripts (4600 molecules per min per embryo) occurs 9-14 hr after fertilization (from blastula stage to hatching). The number of transcripts peaks 21 hr after fertilization (onset of gastrulation) when the embryo has accumulated 1.8 X 10(6) copies of each late mRNA (a 164-fold increase). A 5.5-fold increase in the relative rate of transcription, between 7 and 15 hr after fertilization, is partly responsible for the accumulation of these gene products. The relative synthesis of early histone message, which is encoded by a different family, decreases 18-fold during this time. Synthesis of the late transcripts continues at the higher rate after accumulation has ceased (24 hr after fertilization). The number of late transcripts begins to decrease 48 hr after fertilization, reaching about 10,000 copies at 72 hr.

Transcriptional control of the isoleucine-valine messenger RNA's in E. coli K-12

Hybridization of messenger ribonucleic acid (mRNA) isolated from Escherichia Coli K-12 to deoxyribonucleic acid (DNA) from lambdaCI857st68h80dilv was used to detect isoleucine-valine (ilv) specific mRNA. A number of strains partially constitutive for the isoleucine-valine enzymes had levels of ilv mRNA 2 to 3-fold higher than the parent strain. Starvation for any of the branched-chain amino acids resulted in a 20 to 23-fold increase in ilv mRNA as compared to repressed levels. These differences were not due to altered growth rates or to changes in the stability of ilv mRNA. These data indicate that regulation of the isoleucine-valine enzymes by multivalent repression occurs mainly at the level of transcription. Kinetics of elongation of ilv mRNA after repression are consistent with the assumption that the mechanism of multivalent repression involves the prevention of further initiations by RNA polymerase.