Young Chang Lim

Background: Xerostomia is a pathological condition characterized by decreased salivation due to salivary gland dysfunction and is frequently attributed to irreversible damage as a side effect of radiation therapy. Stem cell–derived organoid therapy has garnered attention as a promising avenue for resolving this issue. However, Matrigel, a hydrogel commonly used in organoid culture, is considered inappropriate for clinical use due to its undefined composition and immunogenicity. In this study, we aimed to develop a method for culturing collagen-based human salivary gland organoids (hSGOs) suitable for clinical applications and evaluated their therapeutic effectiveness. Methods: Human salivary gland stem cells were isolated from the salivary gland tissues and cultured in both Matrigel and collagen. We compared the gene and protein expression patterns of salivary gland–specific markers and measured amylase activity in the two types of hSGOs. To evaluate the therapeutic effects, we performed xenogeneic and allogeneic transplantation using human and mouse salivary gland organoids (hSGOs and mSGOs), respectively, in a mouse model of radiation-induced xerostomia. Results: hSGOs cultured in Matrigel exhibited self-renewal capacity and differentiated into acinar and ductal cell lineages. In collagen, they maintained a comparable self-renewal ability and more closely replicated the characteristics of salivary gland tissue following differentiation. Upon xenotransplantation of collagen-based hSGOs, we observed engraftment, which was verified by detecting human-specific nucleoli and E-cadherin expression. The expression of mucins, especially MUC5B, within the transplanted hSGOs suggested a potential improvement in the salivary composition. Moreover, the allograft procedure using mSGOs led to increased salivation, validating the efficacy of our approach. Conclusions: This study showed that collagen-based hSGOs can be used appropriately in clinical settings and demonstrated the effectiveness of an allograft procedure. Our research has laid the groundwork for the future application of collagen-based hSGOs in allogeneic clinical trials.

Head and neck squamous cell carcinomas (HNSCCs) are highly lethal epithelial tumours containing self-renewal cancer stem cells (CSCs). CSCs in HNSCCs are strongly associated with tumour initiation, invasion, and chemoradiation resistance. However, the important factors regulating stemness in HNSCCs remain unclear. Here, we investigated the molecular roles and clinical significance of inhibitor of DNA binding 2 (Id2) protein to determine if it constitutes a novel therapeutic target for ablating HNSCC cells with stemness. We performed in vitro and in vivo studies of Id2 function and its effects on stemness using HNSCC cells. We also examined whether Id2 expression could be used as a prognostic indicator through immunohistochemical staining of 119 human HNSCC tumours. Expression of Id2 was higher in HNSCC cells with stemness compared with differentiated HNSCC cells. Overexpression of Id2 increased proliferation, self-renewal, and expression of the putative stemness marker CD44 in HNSCC cells in vitro and in vivo. In contrast, silencing of Id2 using short hairpin RNA attenuated the stemness phenotype of HNSCC cells by reducing self-renewal, CD44 expression, cisplatin chemoresistance, and xenograft tumourigenicity. Most importantly, increased expression of Id2 was closely associated with poorer post-treatment survival rates in HNSCC patients. Inhibitor of DNA binding2 represents a novel and promising therapeutic target for treating and improving the clinical outcomes for patients with HNSCC.

Identification of a novel biomarker of subclinical lymph node metastasis (SLNM) in papillary thyroid microcarcinoma (PTMC) could provide important clues regarding SLNM in PTMC. We evaluated the significance of HGF and c-Met expression in surgically removed tumor tissue from PTMC patients as a predictive marker of SLNM. We analyzed the immunohistochemical relationship between HGF and c-Met expression and SLNM in 113 surgically treated PTMC patients with clinically negative nodes presurgery. In addition, we explored whether HGF/c-Met pathway activation enhanced the in vitro migration and invasion of PTC cells. Positive immunohistochemical HGF and c-Met staining was found in 107 (95 %) and 103 (91 %) cases, respectively. The HGF staining distribution was as follows: no staining in 6 cases, weak staining in 43, moderate staining in 55, and strong staining in 9. Of the nine cases with strong HGF staining, eight (89 %) had SLNM. The c-Met staining distribution was as follows: no staining in 10 cases, weak staining in 39, moderate staining in 59, and strong staining in 5. Of the five cases with strong c-Met staining, three (60 %) had SLNM. The presence of SLNM was strongly correlated with HGF and c-Met expression in PTMC in a univariate analysis (P < 0.05). HGF overexpression was also associated with SLNM in a multivariate analysis (P < 0.05). Stimulation with exogenous HGF and constitutive activation of c-Met enhanced the migration and invasion of PTC cells in vitro by enhancing VEGF-A expression. HGF/c-Met pathway activation is associated with SLNM of the central neck in PTMC.

Background: Anaplastic thyroid carcinoma (ATC) is one of the most lethal cancers because of its aggressiveness and the lack of efficacious therapy. Epigallocatechin‐3‐gallate (EGCG), a major catechin in green tea, was shown to possess remarkable therapeutic potential against various types of human cancer cells in in vitro and in vivo models. The aim of this study was to investigate the effect of EGCG on the proliferation and apoptosis of ARO cells—human ATC cells.Study design: Experimental study.Methods: Human ATC cell line, ARO, was treated with EGCG. Cell viability was assessed by MTT assay. Inhibition of EGFR/MAPK pathway and cell cycle‐related proteins by EGCG were measured by Western blot analysis. In addition, cell cycle analysis was measured by flow cytometry.Results: EGCG treatment inhibited the growth of ARO cells in a dose‐dependent manner. Furthermore, EGCG suppressed phosphorylation of EGFR, ERK1/2, JNK, and p38. These changes were associated with increased p21 and reduced cyclin B1/CDK1 expression. In addition, EGCG treatment increased the accumulation of sub‐G1 cell, activated caspase‐3 and cleaved PARP.Conclusions: Taken together, EGCG inhibits cell proliferation and induces apoptosis via suppression of the EGFR/ERK pathway and cyclin B1/CDK1 complex in ATC cells. J. Surg. Oncol. 2011; 104:776–780.

The purpose of this study was to examine the frequency, pattern, and predictive factors associated with occult level II lymph node (LN) metastases in papillary thyroid carcinoma (PTC) patients with clinically metastatic lymph nodes in the lateral neck (level III, IV, and/or V) by preoperative ultrasonography. We retrospectively reviewed the medical records of 52 PTC patients with clinically positive neck lymph nodes in level III, IV, and/or V based on preoperative ultrasonography, who underwent therapeutic lateral neck dissection (ND) (level II–V) between March 2004 and October 2009. All patients had no suspicion of clinically positive neck nodes in level II. Histopathological analysis of neck specimens according to each node level of the neck was performed, with special attention given to level II. Forty-two (81%), 41 (79%), and 6 (12%) patients had histologically positive lymph nodes in level III, IV, and V, respectively. Occult metastases in level II were observed in ten (19%) patients. Patients without suspicious positive LNs in both neck level III and IV by preoperative ultrasonography, and patients without pathologic LN metastases in level III, had no occult LN metastases occurrence to level II. Based on multivariate analysis, presence of more than four metastatic LNs was an independent predictive factor for occult level II metastases [P = 0.022, odds ratio (OR) = 7.738]. Prophylactic level II LN dissection may be omitted in PTC patients with clinically positive neck nodes if suspicious positive lymph nodes in level III are absent during preoperative ultrasonography.