Muneyuki Masuda

The Roles of JNK1 and Stat3 in the Response of Head and Neck Cancer Cell Lines to Combined Treatment with All trans‐retinoic Acid and 5‐Fluorouracil

We have used a combination of vitamin A (all‐trans‐retinyl palmitate), 5‐fluorouracil (5‐FU) and radiation to treat human head and neck squamous cell carcinoma (HNSCC). This chemoradiother‐ apy is called “FAR therapy” In this study we examined the effects of all‐trans‐retinoic acid (ATRA), the active metabolite of vitamin A, and ATRA plus 5‐FU on two HNSCC cell lines (YCU‐ N861 and YCU‐H891) to gain insight into the molecular mechanisms of FAR therapy. ATRA at 1 μM (the order of concentration found in HNSCC tumors treated with FAR therapy) inhibited cell proliferation and caused Gl cell cycle arrest in both cell lines. This was associated with a decrease in cyclin D1, an increase in p27Kipl and a reduction in the hyperphosphorylated form of retinoblastoma protein (pRB). With YCU‐N861 cells, ATRA also caused a decrease in Bcl‐2 and Bcl‐XL and an increase in Bax. Both ATRA and 5‐FU activated c‐Jun N‐terminal kinase (JNK) 1 and the combination of both agents resulted in additive or synergistic activation of JNK1, and also enhanced the induction of apoptosis. The YCU‐H891 cells, in which the epidermal growth factor receptor (EGFR)‐signal transducer and activator of transcription 3 (Stat3) pathway is constitutively activated, were more resistant to treatments with ATRA, 5‐FU and the combination of both agents than YCU‐N861 cells. A dominant negative Stat3 construct strongly enhanced the cellular sensitivity of this cell line to 5‐FU but not to ATRA. In addition there is evidence that activation of Stat3 is associated with cellular resistance to radiation in HNSCC. Therefore, the addition to FAR therapy of agents that inhibit activation of the Stat3 pathway may enhance the clinical response of patients with HNSCC to FAR therapy.

Sulindac sulfide and exisulind inhibit expression of the estrogen and progesterone receptors in human breast cancer cells

In previous studies, we found that sulindac sulfide and exisulind (sulindac sulfone, Aptosyn) cause growth inhibition, arrest cells in the G1 phase of the cell cycle, and induce apoptosis in human breast cancer cell lines. These effects were associated with decreased expression of cyclin D1. The present study focuses on the effects of sulindac sulfide and exisulind on hormone signaling components in breast cancer cells. We found that estrogen receptor (ER)–positive and progesterone receptor (PR)–positive T47D breast cancer cells were somewhat more sensitive to growth inhibition by sulindac sulfide or exisulind than ER-negative PR-negative MB-MDA-468 breast cancer cells. Further studies indicated that sulindac sulfide and exisulind caused marked down-regulation of expression of the ER and PR-A and PR-B in T47D cells. However, neither compound caused a major change in expression of the retinoic acid receptor α (RARα), RARβ, or RARα in T47D cells. Sulindac sulfide and exisulind also caused a decrease in expression of the ER in estrogen-responsive MCF-7 breast cancer cells. Both compounds also markedly inhibited estrogen-stimulated activation of an estrogen-responsive promoter in transient transfection reporter assays. Treatment of T47D cells with specific protein kinase G (PKG) activators did not cause a decrease in ER or PR expression. Therefore, although sulindac sulfide and exisulind can cause activation of PKG, the inhibitory effects of these two compounds on ER and PR expression does not seem to be mediated by PKG. Our findings suggest that the growth inhibition by sulindac sulfide and exisulind in ER-positive and PR-positive human breast cancer cells may be mediated, in part, by inhibition of ER and PR signaling. Thus, these and related compounds may provide a novel approach to the prevention and treatment of human breast cancers, especially those that are ER positive.

Roles of Therapeutic Selective Neck Dissection in Multidisciplinary Treatment

In the treatment of head and neck squamous cell carcinoma (HNSCC), management of cervical lymph nodal metastases has a crucial impact on the prognosis of patients. The “radical neck dissection (RND)”, which was proposed by Crile (Crile, 1906) in 1906, had long been played a role of standard treatment for neck metastases due to its high curability. However, during the last two to three decades, modified neck dissection (MND), also called as “functional neck dissection”, which preserves non-lymphatic structures, has replaced the position of RND, because patients as well as surgeons have become more aware of the significance of the quality of life. In addition, it has become apparent that under current multimodality treatment protocols, MND can achieve improved functional results without compromising oncological outcomes, compared to the conventional RND (Ferlito et al., 2003). Of note, in this study, MND implies the comprehensive (I-V) ND that is generally termed as “modified radical neck dissection (MRND)”, unless described otherwise. Moreover, the detailed studies on the patterns of potential neck metastases clearly demonstrated that the laryngeal and pharyngeal cancers seldom metastasize to the level I and V, while the oral cavity cancers to the level IV and V (Lindberg, 1972; Shah, 1990). These data have strongly encouraged the application of selective neck dissection (SND) that spares the dissection of at least one level in the treatment of clinically N0 neck as “elective” SND (ESND). It is now widely accepted that ESND can achieve similar regional control rates compared to comprehensive neck dissection (CND) (i.e., RND or MRND) in this N0 clinical setting with improved functional outcomes as summarized in a comprehensive review (Ferlito et al., 2006). Recent remarkable advancements in chemoradiation have further extended the application of SND to clinically N+ cases as “therapeutic” SND (TSND) instead of therapeutic CND (TCND). Efficacy of TSND performed either as an initial treatment or as a planed ND (PND) in the course of multidisciplinary treatments has been reported by an increasing number of studies (Ambrosch et al., 2001; Byers et al., 1999; Ferlito et al., 2009; Lohuis et al., 2004; Muzaffar, 2003; Patel et al., 2008; Shepard et al., 2010). Moreover, a recent study by Robins et. al., (Robbins et al., 2005) demonstrated that super selective (i.e., only two levels) neck dissection can achieve quite favorable outcomes, when performed as a PND after RADPLAT. In view of these observations, neck dissection (ND)