Abstract
Purpose.:
Activation or dysregulation of the Sonic hedgehog (Shh) and Wnt signaling pathways is suggested to lead to the development of many human malignancies. In this study, we investigated Shh and Wnt signaling protein expression in eyelid sebaceous gland carcinoma, and analyzed their correlation with clinical characteristics of the tumor.
Methods.:
Patients who underwent surgical resection of eyelid sebaceous gland carcinoma from 1999 to 2011 were recruited for the study. Immunohistochemical stainings of Shh signaling proteins (Shh, Gli-1, Gli-2, Gli-3, and ABCG2) and Wnt signaling proteins (Wnt, glycogen synthase kinase 3β, β-catenin, lipoprotein receptor-related protein [LRP], and c-Myc) were conducted.
Results.:
Thirty-seven cases of eyelid sebaceous gland carcinoma were included in this study. Twenty-nine patients showed no metastasis, and eight patients showed lymph node or distant metastasis. Shh, ABCG2, and Wnt proteins were more highly expressed in the group with metastasis than in the group without metastasis (P = 0.031, P = 0.015, and P = 0.001, respectively; χ2 test). Patients showing high ABCG2 expression, Wnt, or LRP expression developed metastasis more commonly than those with low ABCG2, or without Wnt or LRP expression (log rank test, P = 0.019, 0.001, and 0.000, respectively).
Conclusions.:
The group with metastasis showed higher expression levels of Shh, ABCG2, and Wnt than did the group without metastasis, and patients with strong ABCG2 expression, Wnt, or LRP expression showed higher cumulative incidence of lymph node or distant metastasis, implying that activation of the Shh and Wnt signaling pathway is associated with aggressive behavior of the tumor.
Patients who underwent surgical resection of eyelid sebaceous gland carcinoma in Seoul National University Hospital, Seoul National University Bundang Hospital, and Seoul Municipal Government-Seoul National University Boramae Hospital from 1999 to 2011 were recruited for the study, and their archival paraffin blocks were collected. Thirty-seven paraffin blocks of eyelid sebaceous gland carcinoma were available.
We reviewed the electronic medical records of 37 patients with eyelid sebaceous gland carcinoma. Wide surgical excision with frozen section control was performed as a primary treatment. Reviewed data included demographic information, histopathologic diagnosis, anatomic tumor location, details of treatment, and outcomes such as local recurrence, distant metastasis, and survival. TMN staging was re-established in all cases according to the 2010 American Joint Committee on Cancer (AJCC) (seventh edition). The hematoxylin and eosin-stained slides were independently reviewed in each case to confirm the original diagnosis.
This study was approved by the institutional review board of Seoul National University Bundang Hospital. This study was conducted in compliance with the Declaration of Helsinki.
Patients with eyelid sebaceous gland carcinoma were divided into two groups according to the presence of lymph node or distant metastasis. Demographic data, such as sex and age, were compared between the group with metastasis and the group without metastasis. Immunostaining results were compared between the two groups; χ2 test or Fisher's exact test was used to compare nominal variables, and Mann-Whitney U test was used to compare continuous variables without normality or ordinal variables. Correlations between the expressions of the proteins were analyzed with the Spearman correlation test.
The cumulative incidence of lymph node section or distant metastasis was calculated from the date of surgery until the first day of metastasis detection using the Kaplan-Meier method; patients who had been lost to follow-up without the development of metastasis were considered censored at the date of the last follow-up. Log rank tests were carried out to determine difference in the cumulative incidence of metastasis among comparison groups in univariate analysis. Statistical analyses were performed with SPSS software version 18.0 (SPSS Inc., Chicago, IL). P values less than 0.05 were considered statistically significant.
Shh and Wnt signaling are the key master regulators of vertebrate development.
7,29 In normal mature tissue, the Shh or Wnt pathway is not activated and their signaling molecules are only found during embryogenesis and in stem cells. It has been postulated that reactivation of signaling pathways that are activated during organogenesis and subsequently inactivated in mature tissue, plays a critical role in tumor development and/or progression.
14,17-20,30–33 However, this phenomenon has not been evaluated in eyelid sebaceous gland carcinoma. In this study, we examined the potential involvement of the Shh and Wnt pathways in eyelid sebaceous gland carcinoma by assessing the expression of key downstream effector proteins.
We found that the Shh and Wnt signaling pathways, which are important in organogenesis of the pilosebaceous unit, were activated in eyelid sebaceous gland carcinoma. A significant correlation was also observed between the expression of Shh and ABCG2, molecules of the Shh signaling pathway, suggesting that once Shh had been activated, the whole canonical pathway of Shh was activated. This finding implies that these signaling pathways could be involved, at least in part, in the development of eyelid sebaceous gland carcinoma. Furthermore, the group with metastasis showed higher expression of Shh, ABCG2, and Wnt than the group without metastasis did, and patients with high ABCG2 expression, Wnt, or LRP expression showed higher cumulative incidence of LN or distant metastasis, implying that activation of the Shh and Wnt signaling pathways is also significantly associated with metastatic potential. This finding suggests that activation of the Shh and Wnt signaling pathways is a possible predictive factor for metastasis in eyelid sebaceous gland carcinoma.
Given the different treatment approaches for patients with lymph node metastases and those without metastases, identification of patients with a high risk of lymph node metastasis would have significant implications in treatment decisions. Currently, patients with locally advanced eyelid sebaceous gland carcinoma are treated with wide surgical excision and radical neck dissection to decrease the risk of distant metastasis and provide better disease control.
34 However, sentinel lymph node biopsy in eyelid sebaceous gland carcinoma often yields false-negative results,
35 and there is no predictive biomarker for selecting patients with a significant risk of metastasis. Predictive biomarkers of metastasis would provide clinical benefits to patients with eyelid sebaceous gland carcinoma.
One limitation of our study is that the expression of signaling molecules was not evaluated at the gene or mRNA level.
In summary, we showed that the Shh and Wnt signaling pathways are frequently activated in eyelid sebaceous gland carcinoma and might be associated with metastasis. Risk stratification for metastasis based on this analysis warrants further validation in prospective cohorts of patients with eyelid sebaceous gland carcinoma.