| Summary: | 碩士 === 臺北醫學大學 === 臨床醫學研究所 === 97 === Breast cancer is the fourth cause of female cancer deaths in Taiwan with increased incidence and young age tendency (age?T40 years old, 29.3%). In recent years, the distinct age distribution and more aggressive clinical behavior in the young patient are noted in Taiwanese women and this phenomenon is different from that in the Western countries. Besides, due to the heterogeneity of breast cancer, designation of an ideal treatment protocol for breast cancer could not only be based on the traditionally histological, clinical, and biological markers (such as ER, PR and HER-2/neu) but also some new prognostic factors. Therefore, the specific study of breast cancer in Taiwan women becomes an important issue.
Kruppel-like factors (KLF) belong to a group of zinc finger like transcription factors and are involved in regulating cell proliferation. KLFs have more than twenty subtypes. The studies of Kruppel-like factors in breast cancer are increased recently and are mainly focused on their roles in tumorigenesis. The KLFs are considered as new prognostic factors in breast cancers in some studies. Among them, KLF4 and KLF5 are most important and are broadly studied, but most studies are mainly in Western countries. In order to provide better treatment strategies for native breast cancers, the aim of this study is to evaluate the correlation of KLF4 and KLF5 expression with pathologic changes and clinical behaviors of breast cancers in Taiwanese women.
In the literatures, KLF4 has both tumor suppressor gene and oncogene functions. KLF4 can promote the proliferation of cancer cells and also can regulate production of extracellular matrix. More aggressive clinical manifestations may be associated with the cellular location of KLF4 in cancer cells. The patients have poor prognosis when nuclear localization of KLF4 in cancer cells. KLF5 also has both tumor suppressor gene and oncogene functions. KLF5 can facilitate the proliferation and transformation of cancer cells. Increased expression of KLF5 is a poor prognostic factor and is positively correlated with the expression of HER-2/neu and Ki-67 in breast cancer. KLF5 also has increased expression in breast cancer patients younger than 50 years old.
In this study, we used immunohistochemistry method to evaluate both staining intensity and staining pattern of expression of KLF4 and KLF5 in non-tumor and tumor parts (including invasive and in situ cancers) of breast tissues. We also analyzed the associations of expression status of KLF4 and KLF5 with histological features, clinical presentation and other prognostic factors of breast cancer.
We enrolled 60 breast cancer patients with the mean age 47 years old and the mean tumor size was 2.7 cm. The clinical presentation was stage I: 30.0%; stage II: 43.3%; stage III: 21.7%; and stage IV: 5.0%. The follow-up period of these patients ranged from 8 to 59 months (mean 27 months) and only one patient died of disease. Pathologically, most of them were invasive ductal carcinoma (IDC) (90.0%) and showed moderately differentiation (66.7%). The accompanied ductal carcinoma in situ (DCIS), if present, was predominantly highest grade (60.0%). The immunohistochemical study of KLF4 in cancer cells showed cytoplasmic and nuclear expression. The intensity of tumor part was stronger than non-tumor part in 43.3% patients. We evaluated the association of the immunohistochemical results of KLF4 and KLF5 and clinical manifestations of these patients. We found that more KLF4 nuclear expression in tumor cells positively correlated with more advanced stage (p=0.006) and larger size of the tumor (size more than 2 cm in maximal diameter, p=0.035). KLF4 expression was also age-related. KLF4 intensity was stronger in tumor part than non-tumor part in patients older than 50 years old (p=0.007) and, in this setting, the invasive cancer tended to be poorly differentiated (p=0.033). Besides, consistent expression of KLF4 between DCIS and invasive cancers was also found: stronger intensity in DCIS accompanied with stronger intensity in invasive cancers (p=0.002), more predominant nuclear expression in DCIS with more predominant nuclear expression in invasive cancers (p<0.001). The expression of KLF5 in cancer cells was mainly cytoplasmic. The intensity of tumor part was stronger than non- tumor part in 58.3% patients. For KLF5, invasive breast cancers with negative or weak cytoplasmic expression showed better differentiation compared with strong cytoplasmic expression (p=0.035). Consistent expression of KLF5 between DCIS and invasive cancers was also found: stronger intensity in DCIS with stronger intensity in invasive cancers (p<0.001) and more predominant cytoplasmic expression in DCIS with more predominant cytoplasmic expression in invasive cancers (p<0.001). Moreover, there was no association between the following factors and the KLF4 expression intensity and pattern, respectively: ER (p=0.271 and p=0.925), PR (p=0.191 and p=0.448), HER-2/neu (p=0.136 and p=0.454), p53 (p=1.000 and p=0.925), and p21 (p=0.572 and p=0.367). There was also no correlation between the following factors and the KLF5 expression intensity and staining pattern, respectively: ER (p=1.000 and p=0.512), PR (p=1.000 and p=1.000), and HER-2/neu (p=0.520 and p=0.443).
Our study found that KLF4 expression is positive association with tumor stage, tumor size, and age but could not conduct the conclusion that nuclear KLF4 expression was an adverse prognostic factor proposed in the literatures. In the other hand, KLF5 expression was associated with the differentiation of invasive cancers. We also found that KLF5 nuclear localization was mainly restrictedly in non-tumor breast ducts and lobules (16.7%) and loss of nuclear expression in DCIS and invasive cancers, the finding not mentioned in literatures before. Although we didn’t study the biologic function of KLF5, it maybe presented a possible tumor suppressor gene-like function of KLF5. We found that there were associations of KLF4 and KLF5 expressions and clinical manifestations in breast cancers but the expressions of KLF4 and KLF5 were not enough to predict the prognosis and survival rate. The major cause was due to too short follow up period of our patients to exactly evaluate the association of survival rate and expressions of KLF4 and KLF5. Therefore, well-designed retrospective studies with adequate follow up period for studying correlation of expressions of KLF4 and KLF5 and prognosis and survival rate of breast cancers are necessary.
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