Cytoplasmic expression of survivin is an independent predictor of poor prognosis in patients with salivary gland cancer

Role of Histone Deacetylases in the Pathogenesis of Salivary Gland Tumors and Therapeutic Targeting Options

Salivary gland tumors (SGTs) comprise a rare and heterogenous category of benign/malignant neoplasms with progressively increasing knowledge of the molecular mechanisms underpinning their pathogenesis, poor prognosis, and therapeutic treatment efficacy. Emerging data are pointing toward an interplay of genetic and epigenetic factors contributing to their heterogeneity and diverse clinical phenotypes. Post-translational histone modifications such as histone acetylation/deacetylation have been shown to actively participate in the pathobiology of SGTs, further suggesting that histone deacetylating factors (HDACs), selective or pan-HDAC inhibitors (HDACis), might present effective treatment options for these neoplasms. Herein, we describe the molecular and epigenetic mechanisms underlying the pathology of the different types of SGTs, focusing on histone acetylation/deacetylation effects on gene expression as well as the progress of HDACis in SGT therapy and the current status of relevant clinical trials.

Expression of survivin in oral leukoplakia and oral lichen planus

BACKGROUND

Up to one third (3-33%) oral squamous cell carcinomas develop from potentially malignant lesions. Most common potentially malignant lesions (PML) are Leukoplakia and Lichen planus. It is very important to diagnose PML at early stage to prevent malignant transformation of lesion. Survivin is a smallest member of the Inhibitor of Apoptosis (IAP) family of proteins. Survivin plays an important role in apoptosis regulation. High expression of survivin is an early event during oral carcinogenesis and it acts as a tool for the identification of precancerous lesions at higher risk of progression into invasive carcinoma. The aim of the study was to evaluate the expression of Survivin in oral leukoplakia, oral lichen planus.

METHODS AND MATERIAL

15 patients with oral lichen planus, 15 patients of oral leukoplakia were selected as subjects for the present study and 15 patients with normal oral mucosa were selected as controls and all were evaluated for expression of survivin. All sections were H & E stained and were studied immunohistochemically for the expression of surviving.

RESULTS

Expression of survivin was evaluated based on percent of cells expressing survivin and grading was given according to that. Significant survivin expression was detected in oral leukoplakia, oral lichen planus, (P < 0.001).

CONCLUSIONS

Expression of survivin in potentially malignant lesions indicate potential risk of malignant transformation.

Apoptotic signaling in salivary mucoepidermoid carcinoma

BACKGROUND

Mucoepidermoid carcinoma is the most common malignant tumor of salivary glands. Apoptosis plays an important role in organogenesis of glandular structures, and aberrations of apoptotic mechanisms is associated with a wide array of pathologic conditions.

METHODS

The immunoexpression of proteins associated with apoptosis and proliferation was evaluated in 40 mucoepidermoid carcinoma cases.

RESULTS

Par-4, Survivin, MUC1, PHLDA1, Fas, and Ki-67 were predominantly expressed in mucoepidermoid carcinoma. FasL was rarely expressed, and Caspase-3 expression was observed in almost 50% of the cases. SPARC expression was associated with low-grade tumors, and Ki-67 expression was associated with lymph node metastasis. Expression of Fas and decreased expression of Ki-67 and Caspase-3 were associated with better overall cancer-specific survival rates.

CONCLUSIONS

The association of SPARC and Ki-67 expression with pathological features and the association of Fas, Caspase-3, and Ki-67 with survival probabilities suggest that these proteins may be useful prognostic markers for mucoepidermoid carcinoma.

Down-regulation and nuclear localization of survivin by sodium butyrate induces caspase-dependent apoptosis in human oral mucoepidermoid carcinoma

OBJECTIVE

Sodium butyrate (NaBu) is a histone deacetylase inhibitor that possesses an apoptotic ability. However, the molecular mechanism by which NaBu induces apoptosis in human oral mucoepidermoid carcinoma (MEC), a type of salivary gland tumor, remains unclear.

MATERIALS AND METHODS

The anticancer effects of NaBu and its related molecular mechanisms were determined by trypan blue exclusion assay, 4'-6-diamidino-2-phenylindole staining, live/dead assay, human apoptosis array, RT-PCR, western blotting, immunocytochemistry, preparation of nuclear fractions, and nude mice tumor xenograft.

RESULTS

In this study, we found that NaBu inhibited growth and induced apoptosis in the human oral MEC cell lines MC3 and YD15 with acetylation of histone proteins H2A and H3. NaBu apparently down-regulated survivin protein, as evidenced by the results of the human apoptosis antibody array, and modulated it at the post-translational process. Interestingly, NaBu caused nuclear translocation of survivin protein in both cell lines. NaBu also resulted in decreased expression levels of Bcl-xL mRNA and protein, leading to induction of caspase-dependent apoptosis in human oral MEC cell lines. In addition, NaBu administration inhibited tumor growth in vivo at a dosage of 500 mg/kg/day, but it did not cause any hepatic or renal toxicity.

CONCLUSION

This study provides new insights into the molecular mechanism of apoptotic actions by NaBu in human oral MEC and the basis of its clinical application for the treatment of human oral MEC.

Towards Comprehension of the ABCB1/P-Glycoprotein Role in Chronic Myeloid Leukemia

Abstract: The introduction of imatinib (IM), a BCR-ABL1 tyrosine kinase inhibitor (TKI), has represented a significant advance in the first-line treatment of chronic myeloid leukemia (CML). However, approximately 30% of patients need to discontinue IM due to resistance or intolerance to this drug. Both resistance and intolerance have also been observed in treatment with the second-generation TKIs-dasatinib, nilotinib, and bosutinib-and the third-generation TKI-ponatinib. The mechanisms of resistance to TKIs may be BCR-ABL1-dependent and/or BCR-ABL1-independent. Although the role of efflux pump P-glycoprotein (Pgp), codified by the ABCB1 gene, is unquestionable in drug resistance of many neoplasms, a longstanding question exists about whether Pgp has a firm implication in TKI resistance in the clinical scenario. The goal of this review is to offer an overview of ABCB1/Pgp expression/activity/polymorphisms in CML. Understanding how interactions, associations, or cooperation between Pgp and other molecules-such as inhibitor apoptosis proteins, microRNAs, or microvesicles-impact IM resistance risk may be critical in evaluating the response to TKIs in CML patients. In addition, new non-TKI compounds may be necessary in order to overcome the resistance mediated by Pgp in CML.

Honokiol Radiosensitizes Squamous Cell Carcinoma of the Head and Neck by Downregulation of Survivin

Purpose: Previous studies revealed diverging results regarding the role of survivin in squamous cell carcinoma of the head and neck (SCCHN). This study aimed to evaluate the clinical significance of survivin expression in SCCHN; the function of survivin in DNA-damage repair following ionizing radiation therapy (RT) in SCCHN cells; and the potential of honokiol to enhance RT through downregulation of survivin.Experimental Design: Expression of survivin in SCCHN patient primary tumor tissues (n = 100) was analyzed and correlated with clinical parameters. SCCHN cell lines were used to evaluate the function of survivin and the effects of honokiol on survivin expression in vitro and in vivoResults: Overexpression of survivin was significantly associated with lymph nodes' metastatic status (P = 0.025), worse overall survival (OS), and disease-free survival (DFS) in patients receiving RT (n = 65, OS: P = 0.024, DFS: P = 0.006) and in all patients with SCCHN (n = 100, OS: P = 0.002, DFS: P = 0.003). In SCCHN cells, depletion of survivin led to increased DNA damage and cell death following RT, whereas overexpression of survivin increased clonogenic survival. RT induced nuclear accumulation of survivin and its molecular interaction with γ-H2AX and DNA-PKCs. Survivin specifically bound to DNA DSB sites induced by I-SceI endonuclease. Honokiol (which downregulates survivin expression) in combination with RT significantly augmented cytotoxicity in SCCHN cells with acquired radioresistance and inhibited growth in SCCHN xenograft tumors.Conclusions: Survivin is a negative prognostic factor and is involved in DNA-damage repair induced by RT. Targeting survivin using honokiol in combination with RT may provide novel therapeutic opportunities. Clin Cancer Res; 24(4); 858-69. ©2017 AACR.

Altered expression of apoptosis-regulating miRNAs in salivary gland tumors suggests their involvement in salivary gland tumorigenesis

Salivary gland tumors comprise a heterogeneous group of lesions with different histological features and diverse clinical pathophysiology. They account for about 3% of all head and neck tumors. Apoptosis plays an important role during morphogenesis of glandular structures, including that of the salivary gland. Recent studies have demonstrated that several microRNAs (miRNAs) are involved in the control of apoptosis. The aim of the present study was to determine the expression of apoptosis-related miRNAs (miR-15a, miR-16, miR-17-5p, miR-20a, miR-21, miR-29, and miR-34) and their target mRNAs in 25 pleomorphic adenomas, 23 mucoepidermoid carcinomas, and 10 non-neoplastic salivary gland samples by real-time RT-PCR. We observed upregulation of miR-15a, miR-16, miR-17-5p, miR-21, miR-29, and miR-34a in pleomorphic adenomas. The expression of miR-21 and miR-34a was upregulated in 91 and 74% of mucoepidermoid carcinomas, respectively. Downregulation of miR-20a was observed in 75% of pleomorphic adenomas and in 57% of mucoepidermoid carcinomas. APAF1, BAX, BCL2, BID, CASP2, CASP8, DIABLO , and TP53 transcripts were upregulated in both tumor types. BAD transcripts were upregulated in pleomorphic adenomas. CASP3 and CASP6 transcripts were upregulated in mucoepidermoid carcinomas. BCL2, CASP2, CASP6, and CASP8 proteins were mostly absent in mucoepidermoid carcinomas but expressed in few cells in pleomorphic adenomas. Our study provides evidence of alterations in the expression of apoptosis-regulating miRNAs in salivary gland tumors, suggesting possible involvement of these microRNAs in salivary gland tumorigenesis.

Alternative Pre-mRNA Splicing, Cell Death, and Cancer

Alternative splicing is one of the most powerful mechanisms for generating functionally distinct products from a single genetic loci and for fine-tuning gene activities at the post-transcriptional level. Alternative splicing plays important roles in regulating genes critical for cell death. These cell death genes encode death ligands, cell surface death receptors, intracellular death regulators, signal transduction molecules, and death executor enzymes such as caspases and nucleases. Alternative splicing of these genes often leads to the formation of functionally different products, some of which have antagonistic effects that are either cell death-promoting or cell death-preventing. Differential alternative splicing can affect expression, subcellular distribution, and functional activities of the gene products. Molecular defects in splicing regulation of cell death genes have been associated with cancer development and resistance to treatment. Studies using molecular, biochemical, and systems-based approaches have begun to reveal mechanisms underlying the regulation of alternative splicing of cell death genes. Systematic studies have begun to uncover the multi-level interconnected networks that regulate alternative splicing. A global picture of the complex mechanisms that regulate cell death genes at the pre-mRNA splicing level has thus begun to emerge.

Salivary gland carcinomas

INTRODUCTION

Salivary gland carcinomas are rare tumours of heterogeneous morphology that require distinctive surgical and adjuvant therapy.

METHODS

Relevant studies were electronically searched in PubMed and reviewed for innovative and important information.

RESULTS

Recent insights in genetic alterations like chromosomal aberrations, expression of receptor tyrosine kinases, malfunction of tumour suppressor genes or DNA promoter methylations increased the knowledge about aetiology and pathogenesis. New histological subtypes are recognised, and a three-tiered grading system seems reasonable. Ultrasound remains the basic diagnostic imaging procedure. New developments comprise the diffusion-weighed magnetic resonance imaging, while fluorodeoxyglucose positron emission tomography/computed tomography shows good diagnostic accuracy in detecting distant metastases and local recurrence. Fine-needle aspiration cytology helps in differentiating a neoplasia from a non-neoplastic lesion while being unreliable in recognising malignancy. In contrast, additional core needle biopsy and/or intraoperative frozen section diagnosis increase the accuracy in diagnosing a malignant lesion. Conservative parotid surgery with nerve monitoring remains state-of-the-art. Free flaps or musculoaponeurotic flaps are proposed for prevention of Frey's syndrome. As parotid cancer often shows skip metastases, complete ipsilateral neck dissection (level I-V) is indicated particularly in high-grade lesions. Adjuvant radio(chemo)therapy increases local tumour control, whereas overall survival is not necessarily improved. Current results of systemic chemotherapy or targeted therapy in advanced tumour stages are disappointing.

CONCLUSION

Despite several developments, salivary gland carcinomas remain a heterogeneous group of tumours challenging both pathologists and clinicians.

EGFR, HER2, survivin, and loss of pSTAT3 characterize high-grade malignancy in salivary gland cancer with impact on prognosis

Increased gene copy number (high polysomy or amplification) of EGFR and HER2 has evolved as a predictor for response to targeted therapy. STAT3 and the apoptosis inhibitor survivin represent distinct oncogenes in various human neoplasms. The purpose of this study was to evaluate protein and gene status of these biomarkers by immunohistochemistry and dual color fluorescence in situ hybridization on tissue microarrays of 286 salivary gland carcinomas in the context of clinical and histopathologic characteristics. Diverse tumor types showed overexpression and increased gene copy number of EGFR and HER2. Amplification of HER2 was found in 35.5% of salivary duct carcinomas. Protein overexpression was strongly associated with high gene copy number for both EGFR and HER2 (P < .001). Overexpression and increased gene copy number of EGFR and HER2 were correlated to high-grade malignancy (P < .001) and unfavorable prognosis (P < .001). Strong nuclear staining of survivin was found in 18.9% of tumors and was associated with high-grade malignancy (P < .001), overexpression, and high gene copy number of EGFR and HER2 (P ≤ .05) as well as unfavorable prognosis (P < .001). Overexpression of nuclear pSTAT3 was found in 28.3% of tumors and correlated with well tumor differentiation (P < .001) and favorable prognosis (P = .001). Loss or weak expression of pSTAT3 was inversely associated with overexpression of survivin (P < .001) as well as overexpression and high gene copy number of EGFR and HER2 (P < .05). Overall, overexpression and increased gene copy number of EGFR and HER2 characterize high-grade malignancy with unfavorable prognosis in salivary gland cancer. Nuclear survivin typifies aggressive tumors with worse prognosis, whereas nuclear pSTAT3 might play a role as a tumor suppressor in absence of EGFR, HER2, and survivin.