Kondo Eisaku, Miyake Takayoshi, Shibata Masao, Kimura Toshikazu, Iwagaki Hiromi, Nakamura Shin-Ichi, Tanaka Takehiro, Ohara Nobuya, Ichimura Koichi, Oka Takashi, Yanai Hiroyuki, Shibasaki Futoshi, Yoshino Tadashi
Department of Pathology, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan.
Clin Cancer Res. 2005 Oct 15;11(20):7255-63. doi: 10.1158/1078-0432.CCR-05-0274.
Bcl-2 is a model apoptosis suppressor postulated to promote tumorigenesis. Recently, it has been reported that Bcl-2 undergoes phosphoregulation of its Ser70 to substantially alter its molecular function. Previous studies further suggest that such phospho-Bcl-2 regulation may influence tumor progression in colorectal and other cancers; however, phosphorylation status of the Ser70 of Bcl-2 (pSer70) in vivo in tumors remains obscure. To elucidate this question that may suggest the biological role, we molecularly screened a panel of human colorectal adenomas and adenocarcinomas for endogenous expression of pSer70 Bcl-2.
An antibody specific against pSer70 Bcl-2 was generated for thorough immunohistochemical examination of paraffin-embedded tumor specimens, allowing detection of the endogenously expressed antigen among a range of Bcl-2-positive colorectal neoplasms, including 75 tubular adenomas, 114 adenocarcinomas, and 15 cases of cancer in adenomas.
Loss of pSer70 Bcl-2 expression was observed in adenocarcinomas in a differentiation-dependent manner (positivities: well differentiated 63%, moderately differentiated 52%, and poorly differentiated 12%), whereas tubular adenomas maintained their expression (positivity 88%). Interestingly, an inverse correlation was found between expression of pSer70 Bcl-2 and Ki-67 antigen in those cases of cancer in adenoma (P < 0.01). It was further observed that loss of pSer70 Bcl-2 expression was associated with significantly shorter survival (P < 0.05) and correlated with clinical stages and lymph node metastasis (P < 0.05 and P < 0.05, respectively).
Loss of pSer70 Bcl-2 expression is closely linked to biological aggressiveness in colorectal tumors and represents a statistically significant molecular index for prognosis of patients with these tumors.
Bcl-2是一种被认为可促进肿瘤发生的典型凋亡抑制因子。最近，有报道称Bcl-2的Ser70位点发生磷酸化调节，从而显著改变其分子功能。先前的研究进一步表明，这种磷酸化Bcl-2调节可能影响结直肠癌和其他癌症的肿瘤进展；然而，肿瘤体内Bcl-2的Ser70位点（pSer70）的磷酸化状态仍不清楚。为了阐明这个可能提示生物学作用的问题，我们对一组人类结肠腺瘤和腺癌进行了分子筛选，以检测内源性pSer70 Bcl-2的表达。
制备了一种针对pSer70 Bcl-2的特异性抗体，用于对石蜡包埋的肿瘤标本进行全面的免疫组织化学检查，以便在一系列Bcl-2阳性的结直肠肿瘤中检测内源性表达的抗原，包括75例管状腺瘤、114例腺癌和15例腺瘤性癌。
在腺癌中观察到pSer70 Bcl-2表达缺失，且呈分化依赖性（阳性率：高分化63%，中分化52%，低分化12%），而管状腺瘤保持其表达（阳性率88%）。有趣的是，在腺瘤性癌病例中，pSer70 Bcl-2表达与Ki-67抗原表达呈负相关（P < 0.01）。进一步观察到，pSer70 Bcl-2表达缺失与显著缩短的生存期相关（P < 0.05），并与临床分期和淋巴结转移相关（分别为P < 0.05和P < 0.05）。
pSer70 Bcl-2表达缺失与结直肠肿瘤的生物学侵袭性密切相关，是这些肿瘤患者预后的一个具有统计学意义的分子指标。
