PTOV1 is overexpressed in human high-grade malignant tumors

The prostate tumor overexpressed-1 (PTOV1) protein was first described overexpressed in prostate cancer but not detected in normal prostate. PTOV1 expression is associated to increased cancer proliferation in vivo and in vitro. In prostate biopsy, PTOV1 detection is helpful in the early diagnosis of cancer. The purpose of this study was to analyze the relevance of PTOV1 expression to identify aggressive tumors derived from 12 different histological tissues. Tissue microarrays (TMAs) containing 182 biopsy samples, including 168 human tumors, were analyzed for PTOV1 and Ki67 expression by immunohistochemistry. Tumors of low and high histological grade were selected from lung, breast, endometrium, pancreas liver, skin, ovary, colon, stomach, kidney, bladder, and cerebral gliomas. One TMA with representative tissues without cancer (14 samples) was used as control. PTOV1 expression was analyzed semiquantitatively for the intensity and percentage of positive cells. Ki67 was evaluated for tumors proliferative index. Results show that PTOV1 was expressed in over 95% of tumors examined. Its expression was significantly associated to high-grade tumors (p = 0.014). This association was most significant in urothelial bladder carcinomas (p = 0.026). Overall, the expression of Ki67 was associated to high-grade tumors, and it was significant in several tumor types. PTOV1 and Ki67 were significantly co-overexpressed in all tumors (p = 0.001), and this association was significant in clear cell renal carcinoma (p = 0.005). In conclusion, PTOV1 expression is associated to more aggressive human carcinomas and more significantly to bladder carcinomas suggesting that this protein is a potential new marker of aggressive disease in the latter tumors.     

Immunohistochemical expression of prostate tumor overexpressed 1 in cystoprostatectomies with incidental and insignificant prostate cancer. Further evidence for field effect in prostatic carcinogenesis

Prostate tumor overexpressed 1 was recently identified as a novel gene and protein during a differential display screening for genes overexpressed in prostate cancer. It has been suggested that overexpression of prostate tumor overexpressed 1 can contribute to the proliferative status of prostate tumor cells and, thus, to their biologic behavior. Prostate tumor overexpressed 1 and Ki-67 were immunohistochemically evaluated in prostate cancer, high-grade prostatic intraepithelial neoplasia, and normal-looking epithelium in 20 cystoprostatectomies and 20 radical prostatectomies with pT2a Gleason score 6 prostate cancer. The aim was to see whether there were differences in marker expression between cystoprostatectomies and radical prostatectomies. The proportions of prostate tumor overexpressed 1– and Ki-67–positive cells in the cystoprostatectomies and radical prostatectomies increased from normal-looking epithelium through high-grade prostatic intraepithelial neoplasia, away from and adjacent to prostate cancer, to prostate cancer. Prostate tumor overexpressed 1 expression in prostate cancer in cystoprostatectomies was lower than in radical prostatectomies, the differences being significant; there were significant differences in Ki-67 indices. In conclusion, our findings related to prostate tumor overexpressed 1 expression in high-grade prostatic intraepithelial neoplasia, evaluated adjacent and away from prostate cancer, and in incidental and clinical cancers give further support to the concept of field effect in prostatic carcinogenesis as well as to differences in the process of prostatic carcinogenesis between cystoprostatectomies and radical prostatectomies.     

Notch-1 and Notch-4 biomarker expression in triple-negative breast cancer

Triple-negative breast cancer (TNBC) demonstrates lack of expression of hormone receptors and human epidermal growth factor receptor. However, there is no targeted therapy for TNBC. The authors analyzed 29 TNBC cases for Notch-1 and Notch-4 biomarker expression and subcellular location, Ki67 proliferation rate, and relevant clinical/survival data. Results demonstrated an unfavorable Ki67 rate in 90% of cases, Notch-1 expression in tumor and endothelial cells in 100% of cases, and Notch-4 expression in tumor cells in 73% of cases and endothelial cells in 100% of cases. Additionally, subcellular localization of Notch-1 and Notch-4 was predominantly nuclear and cytoplasmic. In conclusion, (a) the majority of TNBCs are high-grade infiltrating ductal carcinomas with high Ki67 proliferation rate and (b) both Notch-1 and Notch-4 receptors are overexpressed in tumor and vascular endothelial cells with subcellular localization different from that of hormone-positive breast cancer. Targeting Notch signaling with gamma secretase inhibitors should to be explored to further improve the survival rate of TNBC patients.     

Ki67 index and S-phase fraction in human breast carcinomas. Comparison and correlations with prognostic factors

In a prospective study of 148 consecutive breast adenocarcinomas, proliferative indices of the same surgical tumor sample were performed by immunohistologic staining (Ki67 index) with the use of the Ki67 monoclonal antibody, which binds to a nuclear antigen only expressed in cycling cells, and by flow cytometry-derived S-phase fraction (SPF). Measurable Ki67 and SPF indices were obtained in 142 cases and 99 cases, respectively, and in 96 cases by both methods. In aneuploid tumors, a significant but low (P less than 0.05, r = 0.3) relationship was observed between Ki67 index and SPF. When compared with clinical, pathologic, and biochemical parameters these two proliferative indices were shown to be associated with nuclear grading and mitotic index. Additionally, correlations were observed between Ki67 index and node involvement (P less than 0.02) and between SPF and estrogen receptors (P = 0.002). These results show that (1) proliferative indices are obtained in 96% of surgical samples with Ki67 versus 67% with SPF and that (2) Ki67 index and SPF may provide complementary data with respect to prognosis.     

过表达miR-138抑制TCF-4对甲状腺癌细胞CAL-62增殖，凋亡和运动的调节作用

目的　探究过表达miR-138抑制T细胞因子4（TCF-4）对甲状腺癌细胞CAL-62增殖,凋亡和运动的调节作用机制。 方法　转染miR-138 mimic于CAL-62细胞,使用RT-PCR检测miR-138的表达;使用TCF-4构建pcDNA过表达载体转染CAL-62细胞,使用Westen blot检测TCF-4、增殖核抗原67（Ki67）、增殖细胞核抗原（PCNA）、半胱天冬酶3（caspase-3）、半胱天冬酶9（caspase-9）、上皮型钙黏蛋白（E-cadherin）、波形蛋白（Vimentin）和靶基因cycD、c-Myc的表达;使用EDU染色检测细胞增殖;使用Hoechst染色检测细胞凋亡情况;transwell检测细胞侵袭能力。 结果　相比空白组,miR-138转染+TCF-4组caspase-3、caspase-9、Vimentin蛋白表达显著减少,且有显著性差异（P<0.01）;Ki67、PCNA、E-cadherin、cycD、c-Myc蛋白表达显著增加（P<0.01）;甲状腺肿瘤细胞凋亡受到显著抑制（P<0.01）,增殖、侵染受到显著的促进（P<0.01）。相比TCF-4组,miR-138转染+TCF-4组caspase-3、caspase-9、Vimentin蛋白表达显著增加、（P<0.01）;Ki67、PCNA、E-cadherin、cycD、c-Myc蛋白表达显著减少（P<0.01）,抑制了甲状腺肿瘤细胞增殖、侵染（P＜0.01）,凋亡受到了显著的促进（P<0.01）。 结论　表达miR-138抑制TCF-4使得甲状腺癌细胞CAL-62的增殖、侵染受到显著抑制,凋亡受到显著促进。     

过表达miR-138抑制TCF-4对甲状腺癌细胞CAL-62增殖，凋亡和运动的调节作用

目的　探究过表达miR-138抑制T细胞因子4（TCF-4）对甲状腺癌细胞CAL-62增殖,凋亡和运动的调节作用机制。 方法　转染miR-138 mimic于CAL-62细胞,使用RT-PCR检测miR-138的表达;使用TCF-4构建pcDNA过表达载体转染CAL-62细胞,使用Westen blot检测TCF-4、增殖核抗原67（Ki67）、增殖细胞核抗原（PCNA）、半胱天冬酶3（caspase-3）、半胱天冬酶9（caspase-9）、上皮型钙黏蛋白（E-cadherin）、波形蛋白（Vimentin）和靶基因cycD、c-Myc的表达;使用EDU染色检测细胞增殖;使用Hoechst染色检测细胞凋亡情况;transwell检测细胞侵袭能力。 结果　相比空白组,miR-138转染+TCF-4组caspase-3、caspase-9、Vimentin蛋白表达显著减少,且有显著性差异（P<0.01）;Ki67、PCNA、E-cadherin、cycD、c-Myc蛋白表达显著增加（P<0.01）;甲状腺肿瘤细胞凋亡受到显著抑制（P<0.01）,增殖、侵染受到显著的促进（P<0.01）。相比TCF-4组,miR-138转染+TCF-4组caspase-3、caspase-9、Vimentin蛋白表达显著增加、（P<0.01）;Ki67、PCNA、E-cadherin、cycD、c-Myc蛋白表达显著减少（P<0.01）,抑制了甲状腺肿瘤细胞增殖、侵染（P＜0.01）,凋亡受到了显著的促进（P<0.01）。 结论　表达miR-138抑制TCF-4使得甲状腺癌细胞CAL-62的增殖、侵染受到显著抑制,凋亡受到显著促进。     

过表达或抑制肿瘤相关巨噬细胞B7-H1 基因对卵巢癌增殖侵袭的机制研究

目的:探讨过表达或抑制肿瘤相关巨噬细胞(TAM)B7-H1 基因对卵巢癌增殖侵袭的影响及机制。方法:在体外刺激人单核THP-1 细胞成为巨噬细胞,并诱导为TAM,通过腺病毒载体系统过表达(Ad-B7-H1)或抑制(Ad-siB7-H1)TAM中的B7-H1 基因,通过Western blot 检测转染后的TAM 中的B7-H1 表达;单独培养(Alone 组)与过表达(siB7-H1-TAM 组)或抑制(B7-H1-TAM 组)B7-H1 基因的TAM 共培养后, CCK8 法检测CAOV3 细胞的活力。Transwell 小室检测细胞的迁移能力;Western blot 检测Ki67、基质金属蛋白酶2(MMP-2)、基质金属蛋白酶9(MMP-9)、磷酸化的蛋白酪氨酸激酶2(p-JAK2)、磷酸化的信号转导与转录因子3(p-STAT3)。结果:Ad-siB7-H1 组B7-H1 的表达显著低于对照组,Ad-B7-H1 组B7-H1 的表达显著高于对照组(P<0.05);与单独培养组比较,TAM 组细胞活力、细胞侵袭能力及Ki67、MMP-2、MMP-9、p-JAK2 和p-STAT3 的蛋白表达均显著升高(P<0.05),与RFP-TAM 组比较,siB7-H1-TAM 组的细胞活力、细胞侵袭能力及Ki67、MMP-2、MMP-9、p-JAK2 和p-STAT3 的蛋白表达均显著降低,B7-H1-TAM 组的细胞活力、细胞侵袭能力及Ki67、MMP-2、MMP-9、p-JAK2 和p-STAT3 的蛋白表达均显著升高(P<0.05)。结论:抑制肿瘤相关巨噬细胞B7-H1 基因可抑制卵巢癌细胞活力及侵袭能力,下调JAK2/ STAT3 信号通路,过表达B7-H1 基因反之。     

Alterations of cell cycle regulators in localized synovial sarcoma: A multifactorial study with prognostic implications

Genetic alterations of cell cycle regulators are thought to represent uncommon and possible secondary events in sarcomas characterized by recurrent chromosomal translocations. The present study investigates this hypothesis on synovial sarcoma (SS), assessing the frequency of expression and possible clinical implications of detecting alterations in critical cell cycle regulatory proteins. A homogeneous cohort of 49 patients with localized SS, restricted to the extremity and with available long-term follow-up information, was selected from our files. We focused our study on molecules involved in the G1 checkpoint and G1-S transition, including cyclins D1 and E, p21(WAF1), p27(Kip1), mdm2, p53, and Ki67. A cutoff point of 10% immunoreactive tumor cell nuclei was selected to define a positive phenotype for any given marker, except for Ki67. High Ki67 proliferative index was considered when >/=20% tumor cells displayed nuclear immunoreactivity. Biphasic SS were analyzed, taking into account separately the expression of these proteins in the spindle and glandular components. Disease specific survival was modeled using the Kaplan-Meier method with log rank test and Cox regression. The cohort of patients analyzed included 23 females and 26 males, and the histological type distribution was 35 monophasic and 14 biphasic SS. The median follow-up for survivors was 53 months, with a 5-year disease-specific survival of 63% and a metastatic disease-free survival of 40%. The positive phenotypes identified for the different markers studied were as follows: cyclin D1, 59%; cyclin E, 29%; p21, 51%; p27, 69%; mdm2, 59%; p53, 16%; and Ki67, 59%. We observed that positive p53, cyclin E, and high Ki67 proliferative index were correlated with survival, but only Ki67 and p53 were independent variables for prognostication. The present study suggests that alterations of cell cycle regulators are more common events in SS than originally thought. p53 overexpression could be of use as a marker together with a high Ki67 proliferative index, in identifying a subset of SS patients with increased risk of tumor relapse.     

Identification of a novel functional nuclear localization signal in the protein encoded by open reading frame 47 of Bombyx mori nucleopolyhedrovirus

BM47 is encoded by open reading frame 47 of Bombyx mori nucleopolyhedrovirus (BmNPV). BM47 was localized in the nucleus of BmNPV-infected cells. In the present study, we investigated a novel nuclear localization signal (NLS) for BM47 transport and accumulation in the nucleus. By expressing various regions of BM47 fused to enhanced green fluorescent protein (EGFP), we demonstrated that residues 117–148 are necessary for mediating nuclear localization of BM47. Site-directed mutation analysis showed that the two basic residue clusters at positions 117–120 (¹¹⁷RKRR) and 144–148 (¹⁴⁴RKR-K) constitute an authentic NLS for BM47 localization. Finally, we observed that two clusters of basic residues were conserved in BM47 homologues of group-I nucleopolyhedroviruses.     

Cell biological evaluation of liver cell carcinoma, dysplasia and adenoma by tissue micro-array analysis

The clinical and morphological definition of hepatocellular carcinoma (HCC), dysplasia and adenoma suffers from a lack of biological understanding. This is especially important in the histomorphological diagnosis of nodular liver lesions in needle biopsies. Therefore, we constructed a liver tissue micro-array (TMA) and evaluated 48 HCCs, 46 dysplasias, 8 adenomas, 20 cirrhotic specimens and 28 normal liver samples derived from 68 patients. Protein (over)expression by tumor suppressor genes p16, p53 and Rb1 was assessed by immunohistochemistry, the proliferative capacity was examined by immunostaining of Ki67. Further, DNA ploidy status (hyperdiploidy) was measured by fluorescent in situ hybridization (FISH) with a chromosome 1-specific repetitive DNA probe. An abnormal chromosome 1 number, i.e. the percentage of hyperdiploid cells, was 11.0, 13.7, 16.1, 23.7 and 31.3 for normal liver samples, adenomas, cirrhosis, dysplasias and HCCs, respectively. A significant difference was found for HCC versus cirrhosis (P = 0.024) or adenoma (P = 0.033), a trend (borderline significance) was seen for dysplasia versus cirrhosis (P = 0.094). Immunohistochemical protein localisation of p53 and Rb1, as well as Ki67 indicating proliferation, was clearly higher in HCC than in cirrhosis or dysplasia (all P < 0.001). Proliferation was also higher in HCC than in adenoma (P = 0.025), whereas a trend (borderline significance) was observed for Rb1 overexpression (P = 0.063). These data suggest that in the liver cell dysplasia-carcinoma pathway, changes in ploidy are followed by increased proliferation and cell biological perturbations involving p53 and Rb1. Adenomas can be distinguished from carcinomas, but not from dysplasias, based on ploidy and proliferation characteristics.     

The N-terminal 33 amino acid domain of Siva-1 is sufficient for nuclear localization

Siva-1 induces apoptosis in multiple pathological processes and plays an important role in the suppression of tumor metastasis, protein degradation, and other functions. Although many studies have demonstrated that Siva-1 functions in the cytoplasm, a few have found that Siva-1 can relocate to the nucleus. In this study, we found that the first 33 amino acid residues of Siva-1 are required for its nuclear localization. Further study demonstrated that the green fluorescent protein can be imported into the nucleus after fusion with these 33 amino acid residues. Other Siva-1 regions and domains showed less effect on Siva-1 nuclear localization. By site-mutagenesis of all of these 33 amino acid residues, we found that mutants of the first 1-18 amino acids affected Siva-1 nuclear compartmentalization but could not complete this localization independently. In summary, we demonstrated that the N-terminal 33 amino acid residues were sufficient for Siva-1 nuclear localization, but the mechanism of this translocation needs additional investigation.     

Cell membrane reactivity of MIB-1 antibody to Ki67 in human tumors: fact or artifact?

Ki67 immunohistochemistry is a widely used marker of the tumor proliferative fraction. Apart from the nuclear staining of dividing cells, MIB-1 monoclonal antibody was also found to stain the cell membrane of some tumor types. Indeed, such membrane reactivity was proposed as a diagnostic feature of hyalinizing trabecular tumor (HTT) of the thyroid. To verify the diagnostic role of Ki67 membrane pattern, 6 HTTs, 8 pulmonary sclerosing hemangiomas (SH), and 6 other human tumors with MIB-1 cell membrane immunoreactivity were stained by immunoperoxidase with 5 different anti-Ki67 antibodies in different experimental conditions. We show here that the cell membrane reactivity reported in HTT is produced only by MIB-1 and not by other antibodies to Ki67 (including commercially available mouse and rabbit monoclonal antibodies). In addition, this peculiar pattern is obtained only if the reaction is performed at room temperature, because automated immunostainers which operate at 37 degrees C do not produce any MIB-1 membrane localization. The same findings were obtained in the other 6 tumors. Conversely, sclerosing hemangioma of the lung did not produce any MIB-1 cell membrane reactivity in our hands. A cross-reactivity of the MIB-1 monoclonal antibody with an epitope expressed at the cell membrane level (rather than an artifact) seems the most likely explanation for this finding, because the immunoreactivity is generally intense and uniform in the membrane positive tumors. We conclude that when Ki67 immunohistochemistry is used for diagnostic purposes in a suspected HTT, only MIB-1 clone at room temperature should be employed.     

Identification of the nuclear localization and export signals of high risk HPV16 E7 oncoprotein

The E7 oncoprotein of high risk human papillomavirus type 16 (HPV16) binds and inactivates the retinoblastoma (RB) family of proteins. Our previous studies suggested that HPV16 E7 enters the nucleus via a novel Ran-dependent pathway independent of the nuclear import receptors (Angeline, M., Merle, E., and Moroianu, J. (2003). The E7 oncoprotein of high-risk human papillomavirus type 16 enters the nucleus via a nonclassical Ran-dependent pathway. Virology 317(1), 13-23.). Here, analysis of the localization of specific E7 mutants revealed that the nuclear localization of E7 is independent of its interaction with pRB or of its phosphorylation by CKII. Fluorescence microscopy analysis of enhanced green fluorescent protein (EGFP) and 2xEGFP fusions with E7 and E7 domains in HeLa cells revealed that E7 contains a novel nuclear localization signal (NLS) in the N-terminal domain (aa 1-37). Interestingly, treatment of transfected HeLa cells with two specific nuclear export inhibitors, Leptomycin B and ratjadone, changed the localization of 2xEGFP-E7_38-98 from cytoplasmic to mostly nuclear. These data suggest the presence of a leucine-rich nuclear export signal (NES) and a second NLS in the C-terminal domain of E7 (aa 38-98). Mutagenesis of critical amino acids in the putative NES sequence (₇₆IRTLEDLLM₈₄) changed the localization of 2xEGFP-E7_38-98 from cytoplasmic to mostly nuclear suggesting that this is a functional NES. The presence of both NLSs and an NES suggests that HPV16 E7 shuttles between the cytoplasm and nucleus which is consistent with E7 having functions in both of these cell compartments.     

Thioredoxin, a putative oncogene product, is overexpressed in gastric carcinoma and associated with increased proliferation and increased cell survival

Human thioredoxin is a putative oncogene that may confer both a growth and survival advantage to tumor cells. Overexpressed thioredoxin mRNA has been found in both primary human lung and colorectal cancers. To determine the intratumor distribution and amount of thioredoxin protein in human primary carcinomas, we developed an immunohistochemical assay for thioredoxin in paraffin-embedded tissue. We then studied 10 patients with primary high-risk gastric carcinoma. To further relate thioredoxin protein overexpression to cell death and survival, we used a paraffin-based in situ end-labeling (ISEL) assay. To delineate proliferation, we used the nuclear proliferation antigen detected by Ki-67. In this survey, we found that thioredoxin was localized to tumor cells and overexpressed compared with normal gastric mucosa in 8 of 10 gastric carcinomas. The thioredoxin was found at high levels in 5 of the 8 overexpressing carcinomas. The overexpression of thioredoxin was typically found in both a nuclear and cytoplasmic location in the neoplastic cells. There was a significant positive correlation (P = .0061) with cancer cell proliferation measured by Ki-67. There was a significant negative correlation (P = .0001) with DNA damage measured by the ISEL assay, suggesting decreased apoptosis and increased carcinoma cell survival. Thus, human primary gastric tumors that are highly expressive of thioredoxin have both a higher proliferative rate and a higher survival rate than tumors that do not express thioredoxin. With these newly developed assays in hand, it is now feasible to question whether this thioredoxin-related combined growth and survival advantage translates into poor clinical outcome.     

Immunoexpression of Ki67, proliferative cell nuclear antigen, and Bcl-2 proteins in a case of ameloblastic fibrosarcoma

Ameloblastic fibrosarcoma (AFS), regarded as the malignant counterpart of the benign ameloblastic fibroma, is an extremely rare odontogenic neoplasm with only 68 cases reported in the English literature up to 2009. It is composed of a benign odontogenic epithelium, resembling that of ameloblastoma, and a malignant mesenchymal part exhibiting features of fibrosarcoma. Due to the rarity of the lesion, little is known about its molecular pathogenesis; therefore, in the current study, we sought to evaluate the immunoexpression of Ki67, proliferative cell nuclear antigen, and Bcl-2 proteins in AFS, comparing the results obtained with its benign counterpart, as well as to report a new case of this rare entity affecting a 19-year-old female patient. The results obtained revealed that all the proteins evaluated were overexpressed in the malignant mesenchymal portion of AFS if compared with ameloblastic fibroma, suggesting that nuclear proliferative factors such as Ki67 and proliferative cell nuclear antigen, in association to histopathologic features, may be useful markers for identifying the malignancy and that, despite the lack of molecular analysis in the case reported, Bcl-2 alteration may play a role in AFS pathogenesis.     

Nuclear localization of ubiquitin‐activating enzyme Uba1 is characterized in its mammalian temperature‐sensitive mutant

In our previous study, a point mutation in Uba1, the gene encoding ubiquitin‐activating enzyme, was identified in temperature‐sensitive (ts) CHO‐K1 mutant tsTM3 cells, which led to a Met‐to‐Ile substitution at amino acid 256 in Uba1 protein. Characterization of this mutant revealed a deficiency of nuclear Uba1 and impaired ubiquitination in the nucleus. The ts defects in tsTM3 were complemented by the expression of the wild‐type Uba1 tagged with green fluorescent protein (GFP). In this study, the expression and localization of Uba1 were investigated using the various forms of Uba1 tagged with GFP. Western blot analysis and confocal microscopy revealed that nuclear localization of Uba1, as well as even the modified and truncated forms of Uba1, appears to be essential to rescue tsTM3 cells. The localization of Uba1 in the nucleus, even if it was a small amount, was proportional to the efficiency of complementation of tsTM3 cells. Uba1 plays an important role in the nucleus, and a ts mutation found in tsTM3 cells appears to result in the loss of localization of Uba1 in the nucleus.     

Proliferative activity in human glioblastomas: evaluation of different Ki67 equivalent antibodies.

AIMS: Determination of proliferative activity in human gliomas may be of clinical importance. Immunohistochemical estimation of the proliferative index with the prototypic monoclonal antibody Ki67 is often used but has the disadvantage that it must be carried out on frozen material. However, novel Ki67 equivalent antibodies have been developed for use on formalin fixed and paraffin wax embedded tissue. In this study, the prototypic Ki67 antibody and several new Ki67 equivalent antibodies were tested on human glioblastoma tissue. METHODS: Eleven glioblastomas were included in the study. The antibodies used were the prototypic monoclonal Ki67 and the novel Ki67 equivalent antibodies MIB1 (monoclonal), NC-MM1 (monoclonal), NC-Ki67p (polyclonal), and rabbit antihuman Ki67 antigen (polyclonal). The prototypic Ki67 was used on frozen sections and the other Ki67 antibodies on microwave oven heated, formalin fixed and paraffin wax embedded sections. RESULTS: All antibodies exhibited specific granular nuclear staining of weak to strong intensity. In some tumours the labelling indices were within the same range, whereas in others the antibodies elicited divergent values. CONCLUSIONS: All the novel Ki67 equivalent antibodies provided satisfactory staining on paraffin sections. However, a significant spread of labelling indices was recorded in some cases. Therefore, Ki67 immunostaining is encumbered with some degree of uncertainty and requires further optimisation before it can be regarded as a reliable prognostic marker.