Akiko Ishikawa

Novel Therapeutic Strategies for Malignant Salivary Gland Tumors: Lessons Learned from Breast Cancer

Malignant salivary gland tumors (MSGTs) account for 2–6% of all head and neck cancers. Despite the rarity, MSGTs have been of great interest due to a wide variety of pathological features and high metastasis rates resulting in poor prognosis. Surgical resection followed by radiation therapy represents the main treatment of this malignancy. Adjuvant therapy is reserved for the management of local recurrence, no longer amenable to additional local therapy, and for metastasis. Based on the studies from other types of tumors, particularly breast cancer, the expression and function of sex steroid hormone receptors in cancer have been extensively studied and applied to diagnosis and treatment. Although a number of studies in MSGTs have been published, the rationale for hormone therapy is still controversial due to the disparate results and insufficient number of cases. However, some recent reports have demonstrated that certain salivary gland neoplasms are similar to breast cancer, not only in terms of the pathological features, but also at the molecular level. Here, we shed light on the biological similarity between MSGTs and certain types of breast cancer, and describe the potential use of hormone and additional therapies for MSGTs.

Objective validity of an implant-retained overdenture with a ball attachment system after marginal mandibulectomy

Implant-retained overdentures are known to improve oral function, but the clinical impact on patients who have had mandibular resections is still debatable. We have treated 16 patients who had such resections for oral cancer and consequent loss of the alveolar ridge, with overdentures supported by osseointegrated implants and ball attachments. To quantify their functional improvement, we evaluated their maximum bite force and masticatory performance. Their function improved significantly, (from 77.5N - 365N, 371% increase in maximum bite force, p<0.001) and masticatory performance increased (from 2.5 - 7.7, 208%, p<0.0001) after the overdentures had been inserted. While individual changes in maximum bite force showed no significant correlation, those in masticatory performance correlated significantly, which suggests that the subjects with poor masticatory function are likely to benefit from retention of an implant. These results indicate that implant-retained overdentures are an effective way to rehabilitate patients after marginal mandibular resection.

A Case of Impacted Supernumerary Fourth Molar in the Bilateral Mandibular Ramus

Abstract The occurrence of multiple supernumerary teeth in individuals without any associated syndrome is rare. In this report, a rare case of a 48-year-old woman who had an impacted supernumerary fourth molar in the bilateral mandibular ramus is described. She presented with a swelling in the left cheek region. Radiographic examination revealed an impacted supernumerary tooth in the left mandibular ramus with pericoronal resorption of the bone, suggesting peripheral inflammation. She also had an impacted supernumerary tooth on the right side. After administering an antibiotic and antiinflammatory drug, tooth extraction was performed under general anesthesia.

Targeting ID2 expression triggers a more differentiated phenotype and reduces aggressiveness in human salivary gland cancer cells

Inhibitors of DNA‐binding (ID) proteins are negative regulators of basic helix‐loop‐helix transcription factors and generally stimulate cell proliferation and inhibit differentiation. We previously determined that ID1 was highly expressed in aggressive salivary gland cancer (SGC) cells in culture. Here, we show that ID2 is also expressed in aggressive SGC cells. ID2 knockdown triggers important changes in cell behavior, that is, it significantly reduces the expression of N‐cadherin, vimentin and Snail, induces E‐cadherin expression and leads to a more differentiated phenotype exemplified by changes in cell shape. Moreover, ID2 knockdown almost completely suppresses invasion and the expression of matrix metalloproteinase 9. In conclusion, ID2 expression maintains an aggressive phenotype in SGC cells, and ID2 repression triggers a reduction in cell aggressiveness. ID2 therefore represents a potential therapeutic target during SGC progression. ID proteins are negative regulators of basic helix‐loop‐helix transcription factors and generally stimulate cell proliferation and inhibit differentiation. ID2 knockdown triggers important changes in cell behavior, that is, it significantly reduces the expression of N‐cadherin, vimentin and Snail, induces E‐cadherin expression and leads to a more differentiated phenotype exemplified by changes in cell shape. ID2 therefore represents a potential therapeutic target during SGC progression.

Hormone Therapy for the Treatment of Patients with Malignant Salivary Gland Tumor (MSGT)

Malignant salivary gland tumors (MSGTs) account for 2-6% of all head and neck cancers (Glisson et al., 2004; Milano et al., 2007). Despite their rarity, MSGTs have been of great interest because of their wide variety of pathological features and high rates of metastasis, which result in poor prognoses. Surgical resection followed by radiation therapy is the primary therapy for this malignancy. Adjuvant therapy is reserved for the management of local recurrence no longer amenable to additional local therapy and for metastasis. Based on studies of other types of tumors, particularly breast cancer, the expression and function of sex steroid hormone receptors in cancer have been extensively studied and the findings applied to diagnosis and treatment (Clarke & Sutherland, 1990; Kester et al., 1997). Although a number of studies have been published, the rationale for hormone therapy of MSGTs remains controversial because of disparate results and an insufficient number of cases. However, some recent studies have shown that certain salivary gland neoplasms are similar to breast cancer, not only in terms of their pathological features, but also at the molecular level (Pia-Foschini, 2003; Wick et al., 1998; Yoshimura et al., 2007). Here, we shed light on the biological similarity between MSGTs and certain types of breast cancer, and describe the potential use of hormone and additional therapies for MSGTs.