Heming Wu

The Hippo transducer TAZ promotes epithelial to mesenchymal transition and cancer stem cell maintenance in oral cancer

The Hippo pathway has emerged as a fundamental regulator in tissue growth, organ size and stem cell functions, and tumorigenesis when deregulated. However, its roles and associated molecular mechanisms underlying oral squamous cell carcinoma (OSCC) initiation and progression remain largely unknown. Here, we identified TAZ, the downstream effector of Hippo signaling, as a novel bona fide oncogene by promoting cell proliferation, migration/invasion and chemoresistance in OSCC. TAZ promoted epithelial‐to‐mesenchymal transition (EMT) and also was involved in TGF‐β1‐induced EMT in oral cancer cells. Furthermore, enriched TAZ sustained self‐renewal, maintenance, tumor‐seeding potential of oral cancer stem cells (CSCs). Remarkably, enforced TAZ overexpression conferred CSCs‐like properties on differentiated non‐CSCs and fueled phenotypic transition from non‐CSCs to CSCs‐like cells. Mechanistically, TAZ‐TEADs binding and subsequent transcriptional activation of EMT mediators and pluripotency factors are presumably responsible for TAZ‐mediated EMT and non‐CSCs‐to‐CSCs conversion. Importantly, aberrant TAZ overexpression was found to be associated with tumor size, pathological grade and cervical lymph node metastasis, as well as unfavorable prognosis. Pharmacological repression of TAZ by simvastatin resulted in potent anti‐cancer effects against OSCC. Taken together, our findings have revealed critical links between TAZ, EMT and CSCs in OSCC initiation and progression, and also established TAZ as a novel cancer biomarker and viable druggable target for OSCC therapeutics.

Oncogenic roles of Bmi1 and its therapeutic inhibition by histone deacetylase inhibitor in tongue cancer

The polycomb complex protein Bmi1 (B lymphoma Mo-MLV insertion region 1 homolog) mediates epigenetic transcriptional silencing by modifying chromatin structure and is critical for stem cell homeostasis and tumorigenesis. Bmi1 is frequently overexpressed in human malignancies and therefore has key diagnostic and prognostic significance, and holds potential as a therapeutic target. Here we sought to characterize the expression patterns and oncogenic roles of Bmi1 in tongue squamous cell carcinoma and to determine the anticancer effects of histone deacetylase inhibitors (HDACis) via Bmi1 inhibition against tongue cancer. Our data revealed that Bmi1 was aberrantly overexpressed in a significant portion of tongue cancers. Elevated Bmi1 is associated with cervical node metastasis, Ki-67 abundance and reduced overall survival, and also serves as an independent prognostic factor for patient outcomes. Short-hairpin RNA-mediated Bmi1 knockdown inhibited cell proliferation and migration, induced cell apoptosis and senescence, reduced colony formation and CD44+CD133+ sub-population as well as enhanced cisplatin chemosensitivity, presumably by modulation of p16, p14 and E-cadherin. Moreover, HDACi chemicals Trichostatin A (TSA) and sodium butyrate (NaB) potently inhibited Bmi1 and triggered similar phenotypic changes reminiscent of Bmi1 silencing, although TSA treatment seemed paradoxically to induce some epithelial–mesenchymal transition-like changes in tongue cancer cells. Importantly, NaB-induced antitumor effects were partially attenuated by enforced Bmi1 overexpression in vitro. Genetic Bmi1 silencing and pharmacological inhibition of Bmi1 by NaB treatment significantly impaired tumor growth in a tongue cancer xenograft model. Taken together, our results indicate that Bmi1 serves as a key driver and biomarker with multiple oncogenic functions underlying tongue tumorigenesis. Selected appropriate HDACi compounds like NaB may represent novel therapeutic agents against tongue cancer.

Monocarboxylate transporter 4 facilitates cell proliferation and migration and is associated with poor prognosis in oral squamous cell carcinoma patients.

Monocarboxylate transporter 4 (MCT4) is a cell membrane transporter of lactate. Recent studies have shown that MCT4 is over-expressed in various cancers; however, its role in cancer maintenance and aggressiveness has not been fully demonstrated. This study investigated the role of MCT4 in oral squamous cell carcinoma (OSCC), and found that it is highly expressed in OSCC patients by using immunohistochemistry. Moreover, this over-expression of MCT4 was closely associated with tumor size, TNM classification, lymphatic metastasis, distant metastasis and tumor recurrence, and also poor prognosis. To further study mechanisms of MCT4 in vitro, we used small-interfering RNA to silence its expression in OSCC cell lines. The results showed that knock-down of MCT4 decreased cell proliferation, migration, and invasion. The inhibition of proliferation was associated with down-regulation of p-AKT and p-ERK1/2, while decreased cell migration and invasion may be caused by down-regulation of integrin β4-SRC-FAK and MEK-ERK signaling. Together, these findings provide new insight into the critical role of MCT4 in cell proliferation and metastasis in OSCC.

The histone demethylase LSD1 is a novel oncogene and therapeutic target in oral cancer

The histone demethylase LSD1 functions as a key pro-oncogene and attractive therapeutic target in human cancer. Here we sought to interrogate the oncogenic roles of LSD1 in OSCC tumorigenesis and therapeutic intervention by integrating chemical-induced OSCC model, genetic and pharmacological loss-of-function approaches. Our data revealed that aberrant LSD1 overexpression in OSCC was significantly associated with tumor aggressiveness and shorter overall survival. Increased abundance of LSD1 was detected along with disease progression in DMBA- or 4NQO-induced OSCC animal models. LSD1 depletion via siRNA-mediated knockdown in OSCC cells resulted in impaired cell proliferation, migration/invasion, tumorsphere formation and reduced xenograft growth while inducing cell apoptosis and enhancing chemosensitivity to 5-FU. Moreover, treatments of LSD1 chemical inhibitors (pargyline and tranylcypromine) induced its protein reduction probably via enhanced protein degradation and produced similar phenotypic changes resembling LSD1 silencing in OSCC cells. Pharmacological inhibition of LSD1 by intraperitoneal delivery of these inhibitors resulted in impaired xenograft overgrowth. Taken together, our data reveal the tumorigenic roles of LSD1 and identified LSD1 as a novel biomarker with diagnostic and prognostic significance, and also establish that targeting LSD1 by chemical inhibitors is a viable therapeutic strategy against OSCC.

Application of Lateral Arm Free Flap in Oral and Maxillofacial Reconstruction following Tumor Surgery

Objective: To describe the application of lateral arm free flap (LAFF) in reconstruction of defects in the oral and maxillofacial regions following ablative oncological surgery. Subjects and Methods: The study included 16 patients (13 male, 3 female, mean age 56, range 35–69 years). Sixteen LAFF were harvested to reconstruct defects caused by the dissection of malignant tumors of the oral and maxillofacial regions. The tumor was squamous cell carcinoma of the tongue (6 cases), floor of the mouth (4), retromolar area (3), inner cheek (2), and lower gingival (1). Flap sizes ranging from 5 × 7 to 6 × 9 cm were harvested using a sterile tourniquet for bloodless technique. The anastomoses were carried out using a magnifier or microscope. All donor defects were closed primarily. Results: Fourteen flaps healed without venous insufficiency. One flap, in a female patient, survived with mild local microcirculatory obstruction but that of another female patient developed necrosis. There was no significant complication at the donor sites. The advantages of this flap include anatomically reliable vascular supply, accessible donor site, and the aesthetic quality of donor tissue is good. Compared with the radial artery, the posterior radial collateral artery is a nonessential vessel of the arm. The disadvantages are the relatively smaller vessel size for anastomosis and thicker subcutaneous tissue. Conclusions: For the repair of moderate-sized defects of the maxillofacial area, especially in male patients, the LAFF can be recommended.

Long-Term Changes in the Personality and Psychopathological Profile of Opiate Addicts after Nucleus Accumbens Ablative Surgery Are Associated with Treatment Outcome

Objective: To investigate the long-term outcome and changes of the personality and psychopathological profile of opiate addicts after bilateral stereotactic nucleus accumbens (NAc) ablative surgery. Methods: 60 patients were followed up for 5 years and abstinent status and adverse events were evaluated. NAc lesion volumes and locations were obtained by postoperative MRI scans. The Chinese version of the Eysenck Personality Questionnaire (EPQ-RSC), the Symptom Checklist-90-Revised (SCL-90-R), the Beck Depression Inventory (BDI), the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) and the World Health Organization’s Quality of Life Questionnaire – Brief Version (WHOQOL-BREF) were administered to the patients before and 5 years after the stereotactic surgery. Results: The total abstinence rate of all patients in their 5th postoperative year was 47.4%. The abstinent patients had a significantly larger lesion volume than the relapsed ones, but a larger lesion volume also increased the risk of adverse events. 5 years after surgery, the abstinent patients showed significant decreases on the Psychoticism (EPQ-P) and Neuroticism (EPQ-N) scores by EPQ-RSC, a significant decline on the Global Severity Index and the subscores in all 10 dimensions by SCL-90-R, significant decreases on the BDI and Y-BOCS scores, and significant improvements on the scores of all domains by WHOQOL-BREF, while for the relapsed patients, only the subscores of obsessive-compulsive by SCL-90-R and the Y-BOCS scores significantly decreased. Postoperative analysis revealed that the abstinent patients had a significantly better score than the relapsed ones by various instruments, and NAc lesion volumes and locations did not correlate with the outcome of any of these instruments. Conclusion: The bilateral ablation of NAc by stereotactic neurosurgery was a feasible method for alleviating psychological dependence on opiate drugs and preventing a relapse. Long-term follow-up suggested that surgery can improve the personality and psychopathological profile of opiate addicts with a trend towards normal levels, provided persistent abstinence can be maintained; relapse, on the other hand, may ruin this effect.

Lactate dehydrogenase B is associated with the response to neoadjuvant chemotherapy in oral squamous cell carcinoma.

Oral squamous cell carcinoma (OSCC) comprises a subset of head and neck squamous cell carcinoma (HNSCC) with poor therapeutic outcomes and high glycolytic dependency. Neoadjuvant chemotherapy regimens of docetaxel, cisplatin and 5-fluorouracil (TPF) are currently accepted as standard regimens for HNSCC patients with a high risk of distant metastatic spread. However, the antitumor outcomes of TPF neoadjuvant chemotherapy in HNSCC remain controversial. This study investigated the role of lactate dehydrogenase B (LDHB), a key glycolytic enzyme catalyzing the inter-conversion between pyruvate and lactate, in determining chemotherapy response and prognosis in OSCC patients. We discovered that a high protein level of LDHB in OSCC patients was associated with a poor response to TPF regimen chemotherapy as well as poor overall survival and disease-free survival. Our in-depth study revealed that high LDHB expression conferred resistance to taxol but not 5-fluorouracil or cisplatin. LDHB deletion sensitized OSCC cell lines to taxol, whereas the introduction of LDHB decreased sensitivity to taxol treatment. Taxol induced a pronounced impact on LDHB-down-regulated OSCC cells in terms of apoptosis, G2/M phase cell cycle arrest and energy metabolism. In conclusion, our study highlighted the critical role of LDHB in OSCC and proposed that LDHB could be used as a biomarker for the stratification of patients for TPF neoadjuvant chemotherapy and the determination of prognosis in OSCC patients.

Alteration of serum lipid profile and its prognostic value in head and neck squamous cell carcinoma

BACKGROUND Several serum lipid components have been implicated in the development of cancer. However, the prognostic significance of serum lipid components in head and neck squamous cell carcinoma is unknown. Here, we investigated the predictive value of serum lipid profile at diagnosis and in the overall survival of the patients. METHODS The study population consists of 136 pathologically confirmed head and neck squamous cell carcinoma cases diagnosed between years 2009 and 2014 at a tertiary medical center. Levels of preoperative serum lipid components total cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, apolipoprotein A, apolipoprotein B, and lipoprotein (a) were compared between patients and normal controls matched for age and gender. Serum lipid profiles and their association with clinical parameters were analyzed. The effects of the serum lipid components on survival were examined using the proportional hazards regression model to estimate hazard ratio. RESULTS Significant lower levels of cholesterol, low-density lipoprotein, apolipoprotein A, and apolipoprotein B were found in patients with oral cancer (P < 0.0001). However, a significantly higher level of lipoprotein (a) was found in the cancer group (P < 0.0001). Patients with higher lipoprotein (a) had significantly shorter overall survival than those with lower lipoprotein (a) (P = 0.0042). Multivariate analysis showed that both higher lipoprotein (a) and lymph node metastasis are independent prognostic factors in the patient population (P < 0.01). CONCLUSION A higher lipoprotein (a) was associated with poorer prognosis and might be a novel marker in patients with head and neck squamous cell carcinoma.

Medial sural artery perforator flap for postsurgical reconstruction of head and neck cancer.

BACKGROUND This article aims to describe the application of medial sural artery perforator flaps (MSAPs) in reconstruction of defects following ablation of head and neck cancer. METHODS The study included 24 patients (10 males and 14 females). A total of 24 MSAPs were harvested to reconstruct defects caused by the dissection of malignant tumors of the oral and maxillofacial regions. Overall, 20 radial forearm free flaps (RFFs) and 16 anterior lateral thigh perforator flaps (ALTPs) were included in the donor site cosmetic assessments. Visual analog scale (VAS) score was used to assess postoperative oral function and cosmetic results. RESULTS A total of 22 (92%) flaps healed without venous insufficiency. The external diameter of the medial sural artery for anastomosis was 2.2 mm (range, 1.3-2.5 mm), and the external diameter of the venae comitantes was 2.6 mm (range, 1.5-3.5 mm). Esthetic satisfaction with the primary site had a VAS score of 6.38 ± 1.89, while the donor site had a score of 7.34 ± 1.28. Use of MSAP and ALTP showed significantly higher esthetic satisfaction at the donor site than with RFF (p < 0.001 and p < 0.05, respectively). CONCLUSION MSAPs show a strong advantage for donor site esthetic outcome and can be a good choice for the repair of defects of the maxillofacial area after cancer ablation.

Altered expression of podoplanin in keratocystic odontogenic tumours following decompression

Marsupialisation or decompression is frequently performed as a conservative therapy for keratocystic odontogenic tumours (KCOTs). Positive podoplanin (PDPN) expression in the epithelium of KCOT has been previously reported and may be associated with neoplastic invasion. In the present study, changes in PDPN expression were observed in the epithelium of KCOTs following decompression. In total, 16 pairs of paraffin-embedded tissue specimens obtained at the time of decompression and at two-stage curettage or enucleation were collected and immunohistochemically examined using an antibody against PDPN. The intensity of PDPN staining was evaluated with a semi-quantitative detection method and statistically analysed. The immunohistochemical reactivity of PDPN was consistently markedly positive in 93.8% of KCOT samples prior to decompression. The positive staining was immunolocalised to the cell membrane and cytoplasm of cells in the basal layer and extended into the suprabasal layer for two to three cell layers. At the time of curettage, 2 of the 16 (12.5%) cases were completely negative, 11 of the 16 (68.8%) cases were locally positive and 3 of the 16 (18.7%) cases showed a ‘linear staining’ pattern, as the PDPN-positive cells were restricted to within the single basal layer. The expression level of PDPN was significantly decreased (P<0.05) and a significant loss or reduction of PDPN expression was observed in KCOTs following decompression. Larger sample groups are required to further verify this result.