Detection of mycoplasma infection in circulating tumor cells in patients with hepatocellular carcinoma.

Many studies have shown that persistent infections of bacteria promote carcinogenesis and metastasis. Infectious agents and their products can modulate cancer progression through the induction of host inflammatory and immune responses. The presence of circulating tumor cells (CTCs) is considered as an important indicator in the metastatic cascade. We unintentionally produced a monoclonal antibody (MAb) CA27 against the mycoplasmal p37 protein in mycoplasma-infected cancer cells during the searching process of novel surface markers of CTCs. Mycoplasma-infected cells were enriched by CA27-conjugated magnetic beads in the peripheral blood mononuclear cells in patients with hepatocellular carcinoma (HCC) and analyzed by confocal microscopy with anti-CD45 and CA27 antibodies. CD45-negative and CA27-positive cells were readily detected in three out of seven patients (range 12-30/8.5 ml blood), indicating that they are mycoplasma-infected circulating epithelial cells. CA27-positive cells had larger size than CD45-positive hematological lineage cells, high nuclear to cytoplasmic ratios and irregular nuclear morphology, which identified them as CTCs. The results show for the first time the existence of mycoplasma-infected CTCs in patients with HCC and suggest a possible correlation between mycoplasma infection and the development of cancer metastasis.

The expression of phospho-AKT1 and phospho-MTOR is associated with a favorable prognosis independent of PTEN expression in intrahepatic cholangiocarcinomas.

AKT1 signaling pathway is important for the regulation of protein synthesis and cell survival with implications in carcinogenesis. In this study, we explored the prognostic significance of AKT1 pathway in intrahepatic cholangiocarcinomas. We investigated the status of phosphatase and tensin homolog deleted on chromosome 10 (PTEN), phosphorylated (p) AKT1 (p-AKT1), p-mammalian target of rapamycin (p-MTOR), p-p70 ribosomal protein S6 kinase (p-RPS6KB2) and p-eukaryotic initiation factor 4E-binding protein-1 (p-EIF4EBP1) in 101 intrahepatic cholangiocarcinomas by immunohistochemistry. Western blot analysis was performed to verify the expression levels of p-AKT1 and p-MTOR. The relationship of protein expression with clinicopathological data and the correlations of protein expression levels were explored. The overexpression of p-AKT1, p-MTOR, and PTEN was associated with a better survival in patients with intrahepatic cholangiocarcinoma (P=0.0137, 0.0194, and 0.0337, respectively). In a multivariate analysis, PTEN was an independent prognostic factor, and p-AKT1 showed tendency (P=0.032 and 0.051, respectively). The overexpression of p-MTOR was correlated with well-to-moderately differentiated tumors (P<0.001) and tumors without metastasis (P=0.046). Expression levels of the AKT1 signaling pathway proteins in this study showed positive correlations with each other, except for PTEN. Aberrant expressions of p-AKT1 and p-MTOR in intrahepatic cholangiocarcinoma were associated with a favorable prognosis, possibly in a PTEN-independent manner. Our results indicate that dysregulation of the AKT1 pathway may have an important role in the development of intrahepatic cholangiocarcinoma, but not necessarily in the progression of the disease.

Overexpression of renal tumor antigen is associated with tumor invasion and poor prognosis of hepatocellular carcinoma.

PURPOSE: The aim of this study was to investigate the roles of renal tumor antigen (RAGE) in the progression and clinical outcome of hepatocellular carcinoma (HCC). METHODS: RAGE mRNA levels in 350 cases of HCC were investigated by quantitative real-time reverse transcription polymerase chain reaction. We analyzed the relationship of RAGE mRNA level with clinicopathologic parameters and clinical outcome. To identify the possible role of RAGE on cellular invasion, we performed in vitro analyses using small interfering RNAs (siRNAs). RESULTS: RAGE mRNA level was significantly higher in HCC than in noncancerous hepatic tissues (P < 0.001). Overexpression of RAGE was significantly correlated with the presence of multiple tumors (P = 0.021), high alfa-fetoprotein level (P = 0.042), and advanced tumor stage (P = 0.016). Higher levels of RAGE expression were associated with significantly shorter overall survival time (P = 0.029). Knockdown of RAGE expression by siRNAs suppressed the invasive ability of HCC cells and the expression and secretion of matrix metalloproteinase-9 (MMP-9). We found that RAGE and MMP-9 expressions were correlated in HCCs, and furthermore, the combination of RAGE and MMP-9 expression was associated with the survival of patients (P = 0.0066). CONCLUSIONS: Our results suggest that RAGE may be important in tumor invasion and could be a potential predictor for the prognosis of HCC patients.

Epithelial-mesenchymal transition gene signature to predict clinical outcome of hepatocellular carcinoma.

Hepatocellular carcinoma is one of the most lethal cancers worldwide. More accurate stratification of patients at risk is necessary to improve its clinical management. As epithelial-mesenchymal transition is critical for the invasiveness and metastasis of human cancers, we investigated expression profiles of 12 genes related to epithelial-mesenchymal transition through a real-time polymerase chain reaction. From a univariate Cox analysis for a training cohort of 128 hepatocellular carcinoma patients, four candidate genes (E-cadherin [CDH1], inhibitor of DNA binding 2 [ID2], matrix metalloproteinase 9 [MMP9], and transcription factor 3 [TCF3]) with significant prognostic values were selected to develop a risk score of patient survival. Patients with high risk scores calculated from the four-gene signature showed significantly shorter overall survival times. Moreover, the multivariate Cox analysis revealed that four-gene signature (P = 0.0026) and tumor stage (P = 0.0023) were independent prognostic factors for overall survival. Subsequently, the four-gene signature was validated in an independent cohort of 231 patients from three institutions, in which high risk score was significantly correlated with shorter overall survival (P = 0.00011) and disease-free survival (P = 0.00038). When the risk score was entered in a multivariate Cox analysis with tumor stage only, both the risk score (P = 0.0046) and tumor stage (P = 2.6 x 10(-9)) emerged as independent prognostic factors. In conclusion, we suggest that the proposed gene signature may improve the prediction accuracy for survival of hepatocellular carcinoma patients, and complement prognostic assessment based on important clinicopathologic parameters such as tumor stage.

p53 alteration independently predicts poor outcomes in patients with endometrial cancer: a clinicopathologic study of 131 cases and literature review.

OBJECTIVE: The aim of this study was to evaluate the prognostic impact of p53 alteration in human uterine endometrial adenocarcinoma. METHODS: One hundred and thirty-one patients with primary endometrial adenocarcinoma were included in the study. The p53 mutation and/or protein expression were evaluated by polymerase chain reaction-single-strand conformational polymorphism and by immunohistochemical analysis, respectively. Clinical and pathological parameters were obtained from medical records. Survival data were estimated using Kaplan-Meier estimates and compared with the log-rank test where indicated. Multivariate analysis was performed using the Cox regression method. RESULTS: Thirty nine cases (29.8%) containing p53 alterations had a lower disease specific-survival rate and disease-free survival rate than those without p53 alterations. Statistically significant correlations were seen between p53 alteration and non-endometrioid histology type, high grade tumors, and the absence of progesterone receptor. Multivariate analyses showed that both p53 alteration and FIGO stage at diagnosis were adverse prognostic factors. The group of women with p53 alteration had an 11.0-fold increased risk of disease specific death (95% confidence interval: 1.008-120.765) compared to women whose tumors lacked p53 alteration. CONCLUSION: p53 alteration defines a subset of endometrial adenocarcinoma with highly aggressive behavior and predicts lower survival in patients with endometrial adenocarcinoma.

Comparative proteomic analysis of mouse melanoma cell line B16, a metastatic descendant B16F10, and B16 overexpressing the metastasis-associated tyrosine phosphatase PRL-3.

Metastasis is a complex, multistep process by which a cancer cell leaves the primary tumor, travels to a distant site via the circulatory system, and establishes a secondary cancer. A deeper understanding of the molecular events underlying metastasis will provide information that will be useful for the development of new diagnostic and therapeutic strategies. The B16 and B16F10 mouse melanoma cell lines are widely used as model system for studying many aspects of cancer biology including metastasis. Compared with B16, which has a low metastatic potential, the highly metastatic cell line B16F10 displayed a higher metastatic ability along with higher expression levels of the metastasis-associated phosphatase of regenerating liver-3 (PRL-3). B16 cells transfected with PRL-3 cDNA (B16-PRL3) had metastatic abilities comparable to those of Bl16F10 cells. To study the molecular mechanisms that underlie metastasis, the proteomes of the B16, B16F10, and B16-PRL3 cell lines were compared using two-dimensional differential in-gel electrophoresis. Proteins that varied significantly in levels between these cell lines were selected and identified using mass spectrometry. Interestingly, many proteins, especially those present in membrane fractions, were similarly up- or downregulated in both the Bl16F10 and B16-PRL3 cells lines compared to B16 cell lines. The list of similarly regulated proteins included heat shock protein 70, fascin-1, septin-6, ATP synthase beta subunit, and bone morphogenic protein receptor type IB. These proteins may play a causal role in PRL-3-mediated metastasis. These investigations open an avenue for the further characterization of the molecular mechanisms that underlie metastasis.

Expression of cystathionine beta-synthase is downregulated in hepatocellular carcinoma and associated with poor prognosis.

The cystathionine beta-synthase (CBS) gene encodes an enzyme that catalyzes the synthesis of cystathionine in the trans-sulfuration pathway and is subject to tight regulation because of its critical role in antioxidant and methylation metabolism. The expression level of CBS in 120 hepatocellular carcinoma (HCC) specimens evaluated by real-time reverse transcriptase PCR (RT-PCR) is markedly lower than in surrounding non-cancerous liver (P<0.0001). The correlation between CBS gene expression in HCC and clinicopathological parameters or survival of HCC patients was statistically analyzed in the present study. Our study demonstrated that reduced CBS expression is significantly correlated with high tumor stage (P=0.0019), high Edmondson grade (P=0.00084), and high AFP level (P=6.2x10(-5)). Interestingly, a survival analysis showed that a significantly shorter overall survival (OS) time is observed in patients with reduced CBS expression (P=0.0022), although CBS expression was determined not to be an independent prognostic factor for OS (P=0.071) after considering tumor stage, tumor size, and AFP level. However, for the 62 patients with low AFP levels (<100 ng/ml), reduced CBS expression was found to be an independent prognostic factor for OS (P=0.0042) after considering tumor stage and tumor size. Thus, the expression level of CBS mRNA could be useful to predict clinical outcome of HCC, especially for patients with low AFP levels.

Effectiveness of each Bethesda marker in defining microsatellite instability when screening for Lynch syndrome.

BACKGROUND/AIMS: A panel of five markers (two mononuclotide markers and three dinucleotide markers; the so-called Bethesda markers) has been proposed to define MSI status. However reducing these 5 markers into one or two markers have been suggested to be sufficient for detection of the MLH1- or MSH2-mutated Lynch syndrome. We attempted to examine the effectiveness of each Bethesda marker for the determination of MSI status clinically relevant to Lynch syndrome. METHODOLOGY: We compared the MSI status obtained using each or a combination of two Bethesda markers to those obtained using all five Bethesda markers in 1,531 non-selected colorectal cancer patients. RESULTS: At least one mononucleotide marker was unstable in 94% of the MSI-H tumors defined by the Bethesda markers (126 of 134). After sequencing MLH1 and MSH2 genes from 31 of 86 patients eligible for the genetic test, 18 germline mutations were detected. Seventeen of these mutations were from high MSI tumors, and 1 was from a MSS tumor defined by 5 Bethesda markers. A combination of two mononucleotide markers was able to identify all 17 mutation-positive individuals with MSI-H tumors defined by the five Bethesda markers. CONCLUSIONS: Instability in two mononucleotide markers, BAT26 and BAT25, was most effective markers at defining MSI status. Sensitivity is only slightly impaired by using two mononucleotide markers instead of five markers.

Carcinogenic risk of human papillomavirus (HPV) genotypes and potential effects of HPV vaccines in Korea.

This study investigated the distribution of HPV types in Korean women and evaluated the carcinogenic risk of individual HPV types and the potential effects of HPV vaccines. A total of 4,081 HPV-positive samples between 2014 and 2017 were included. The most prevalent genotypes were HPV 16, 58, 68, and 56. Among them, HPV 16 was significantly higher in high-grade squamous intraepithelial neoplasia or worse (HSIL+ ) group. In cytologically evaluating the risk for HSIL+ by individual HPV types, HPV 16 was associated with the highest risk of HSIL+ (OR = 10.82; 95% CI: 7.93-14.77), followed by HPV 33, 31, 52, 18, 58, 51, and 35, in descending order (OR = 3.50 [type 33] to 2.62 [type 35]). Among those types, HPV 16, 18, 31, 33, and 58 were also significantly associated with HSIL+ on histologic evaluation. The analysis of the HPV subgroups covered by the different vaccines revealed that the HPV types covered by the 9-valent vaccine had a high association with HSIL+ (OR = 4.09; 95% CI: 3.02-5.54). Our findings highlight the different carcinogenic risks posed by the high risk HPV genotypes and the positive potential effects of the 9-valent HPV vaccine in reducing HPV-associated cervical cancer in Korea.

Phosphorylation of p53 Serine 15 Is a Predictor of Survival for Patients with Hepatocellular Carcinoma.

Background: Hepatocellular carcinoma (HCC) is one of the most common malignant cancers with a poor prognosis. Several commonly investigated immunohistochemical markers in resected HCC have potential prognostic value, but the prognostic utility of p53 expression in HCC has remained elusive. Aim: To evaluate the prognostic value of p53 and p53 phosphorylation at serine 15 (p53 Ser15-P) in patients with HCC. Methods: Surgically resected tumors from 199 HCC patients were analyzed for p21, p53, p53 Ser15-P, and proliferating cell nuclear antigen (PCNA) expression using immunohistochemistry. Results: Stratifying by the expression of p53 Ser15-P (P = 0.016), but not by p53 (P = 0.301), revealed significantly different survival outcomes in patients with HCC. Moreover, our analysis demonstrated that patients who were PCNA-positive and p53 Ser15-P-negative had significantly worse survival outcomes (P = 0.001) than patients who were PCNA-positive and p53 Ser15-P-positive. Conclusions: P53 Ser15-P is associated with poor outcomes in patients with HCC, and this prognostic marker is useful for predicting the survival of patients with PCNA-positive HCC.

Composite marginal zone B cell lymphoma and enteropathy-type T cell lymphoma of the stomach: a case report.

We describe a 64-year-old patient with gastric synchronous extranodal marginal zone B cell lymphoma of mucosa-associated lymphoid tissue and enteropathy-type T cell lymphoma. The simultaneous occurrence of mucosa-associated lymphoid tissue lymphoma and enteropathy-type T cell lymphoma is exceptional and has never been reported. We discuss the possible pathogenetic relationship between the two neoplasms.

Detection of human papillomavirus DNA by DNA chip in breast carcinomas of Korean women.

It remains unclear whether there is an association between human papillomavirus (HPV) infection and human breast cancer. The aim of this study was to investigate the presence of HPV DNA in breast carcinomas of Korean women and to examine the possible association between HPV and breast cancer development. For this purpose, HPV DNAs from 154 patients, including 123 patients with breast carcinoma and 31 with intraductal papilloma, and nipple tissue from 27 cancer patients were examined using the DNA chip method. HPV DNA was detected in 8 breast carcinomas (6.5%) but in no intraductal papilloma. All detected HPV genotypes were of high-risk groups. There was a slightly increased incidence in papillary carcinomas (11.5%) and invasive ductal carcinomas with adjacent intraductal papillomas (11.8%) compared to the other histological subtypes (3.2-4.3%), although the difference was not statistically significant (p = 0.126). The presence of HPV DNA was not correlated with specific prognostic predictors of disease. High-risk HPV DNA sequences were present in 6.5% of Korean patients with breast tumors. However, this study could not demonstrate whether or not such HPVs directly contribute to the development of breast cancer.

Correction: Mapping of a Mycoplasma-Neutralizing Epitope on the Mycoplasmal p37 Protein.

[This corrects the article DOI: 10.1371/journal.pone.0169091.].

Cell-surface major vault protein promotes cancer progression through harboring mesenchymal and intermediate circulating tumor cells in hepatocellular carcinomas.

Circulating tumor cells (CTCs) play a major role in the metastasis and recurrence of hepatocellular carcinoma (HCC). Here, we found that major vault protein (MVP) is expressed on the surface of HCC cells and further induced under stressful environments. MVP knockdown reduces cell proliferation and induces apoptosis in HCC cells. Treatment of HCC cells with anti-MVP antibody (α-MVP) recognizing cell-surface MVP (csMVP) inhibits cell proliferation, migration, and invasion. csMVP-positive HCC cells have a higher clonogenic survival than csMVP-negative HCC cells, and treatment of HCC cells with α-MVP inhibits clonogenic survival, suggesting that csMVP contributes to HCC cell survival, migration, and invasion. The function of csMVP is mediated through mTOR, FAK, ERK and Akt signaling pathways. csMVP-positive CTCs are detected in HCC patients (89.7%) but not in healthy donors, and the number of csMVP-positive CTCs is further increased in patients with metastatic cancers. csMVP is exclusively detectable in CTCs with mesenchymal phenotype or intermediate phenotype with neither epithelial nor mesenchymal markers, suggesting that csMVP-associated survival and metastatic potential harbor CTCs with nonepithelial phenotypes. The results suggest that csMVP promotes cancer progression and serves as a surface marker for mesenchymal and intermediate CTCs in patients with HCC and metastatic cancers.

Mapping of a Mycoplasma-Neutralizing Epitope on the Mycoplasmal p37 Protein.

Many studies have shown that the mycoplasmal membrane protein p37 enhances cancer cell migration, invasion, and metastasis. Previously, we generated 6 monoclonal antibodies (MAbs) against the mycoplasmal protein p37 and showed the presence of mycoplasma-infected circulating tumor cells in the blood of hepatocellular carcinoma patients by using CA27, one of the six MAbs. When mycoplasmas were incubated with cancer cells in the presence of CA27, mycoplasma infection was completely inhibited, suggesting that CA27 is a neutralizing antibody inhibiting mycoplasma infection. To examine the neutralizing epitope of CA27, we generated a series of glutathione S-transferase (GST)-fused p37 deletion mutant proteins in which p37 was partly deleted. To express p37-coding sequences in E.coli, mycoplasmal TGA codons were substituted with TGG in the p37 deletion mutant genes. GST-fused p37 deletion mutant proteins were then screened to identify the epitope targeted by CA27. Western blots showed that CA27 bound to the residues 216-246 on the middle part of the p37 protein while it did not bind to the residues 183-219 and 216-240. Fine mapping showed that CA27 was able to bind to the residues 226-246, but its binding activity was relatively weakened as compared to that to the residues 216-246, suggesting that the residues 226-246 is essential for optimal binding activity of CA27. Interestingly, the treatment of the purified GST-tagged epitopes with urea showed that CA27 binding to the epitope was sodium dodecyl sulfate-resistant but urea-sensitive. The same 226-246 residues were also recognized by two other anti-p37 MAbs, suggesting that the epitope is immunodominant. The identification of the novel neutralizing epitope may provide new insight into the interaction between the p37 protein and host receptors.

Microsatellite instable double primary cancers of the colorectum and stomach exhibit less favorable outcome.

AIM: To ascertain the adequacy of the microsatellite instability (MSI) as a prognostic indicator by assessing MSI status of patients with double primary gastric and colorectal cancer (DPGCC). METHODS: Sixteen patients were studied, all of whom exhibited sporadic DPGCC, and had no family history of hereditary non-polyposis colorectal cancer, according to the Amsterdam criteria. A total of 32 cancers from 16 DPGCC patients, and 216 single primary CRC, were assessed for MSI in 5 microsatellite loci, BAT25, BAT26, D2S123, D5S346, and D17S250. RESULTS: MSI was observed in 6 (37.5%) of 16 GC and 4 (25.0%) of 16 CRC. Thirty tumors (13.9%) out of 216 single primary CRC and one tumor (16.7%) out of 6 double primary CRC were found to be microsatellite unstable. Of the 6 GC with MSI in DPGCC, 5 (31.3%) were MSI-high and one (6.3%) was MSI-low. In 5 of 16 DPGCC patients, the cancer recurred in or adjacent to the anastomosis or metastasized to the kidney or lung. The MSI-high DPGCC cases were associated with a younger age of onset (47.5 years vs 62.5 years), higher frequency of lymph node metastasis (100% vs 25%), and advanced Dukes stage (C, 100% vs 41.7%), as well as a higher frequency of recurrence or metastasis (100% vs 8.3%). Only recurrence or metastasis showed statistical significance by Fisher's exact test. CONCLUSION: Our data suggest that MSI may play an important role in the development of DPGCC, and that it may be used clinically as a molecular predictive marker for recurrence or late metastasis of DPGCC.

Actionable gene expression-based patient stratification for molecular targeted therapy in hepatocellular carcinoma.

BACKGROUND: The effectiveness of molecular targeted agents is modest in hepatocellular carcinoma (HCC). Efficacy of molecular targeted therapies has been better in cancer patients with high expression of actionable molecules defined as cognate target molecules. However, patient stratification based on the actionable molecules dictating the effectiveness of targeted drugs has remained understudied in HCC. EXPERIMENTAL DESIGN & RESULTS: Paired tumor and non-tumoral tissues derived from a total of 130 HCC patients were studied. Real-time RT-PCR was used to analyze the mRNA expression of actionable molecules in the tissues. mRNA levels of EGFR, VEGFR2, PDGFRß, FGFR1, and mTOR were up-regulated in tumors compared to non-tumors in 35.4, 42.3, 61.5, 24.6, and 50.0% of patients, respectively. Up-regulation of EGFR was observed at early stage and tended to gradually decrease toward late stages (BCLC stage A: 41.9%; B: 30.8%; C: 17.6%). Frequency of VEGFR2 expression in tumors at stage C was lower than that in the other stages (BCLC stage A: 45.9%; B: 41.0%; C: 29.4%). PDGFRß and mTOR were observed to be up-regulated in more than 50% of tumors in all the stages whereas FGFR1 was up-regulated in only about 20% of HCC irrespective of stages. A cluster analysis of actionable gene expression revealed that HCC can be categorized into different subtypes that predict the effectiveness of molecular targeted agents and combination therapies in clinical trials. Analysis of in vitro sensitivity to sorafenib demonstrated that HCC cells with up-regulation of PDGFRß and c-Raf mRNA are more susceptible to sorafenib treatment in a dose and time-dependent manner than cells with low expression of the genes. CONCLUSIONS: mRNA expression analysis of actionable molecules could provide the rationale for new companion diagnostics-based therapeutic strategies in the treatment of HCC.

Overexpression of high-mobility group box 2 is associated with tumor aggressiveness and prognosis of hepatocellular carcinoma.

PURPOSE: We investigated the expression of high-mobility group box 2 (HMGB2) in patients with hepatocellular carcinoma (HCC) and its clinical effects with underlying mechanisms. EXPERIMENTAL DESIGN: HMGB2 mRNA levels were measured in 334 HCC patients by real-time reverse transcription-PCR and HMGB2 protein levels in 173 HCC patients by immunohistochemical studies. The HMGB2 expression level was measured by Western blotting for three HCC cell lines. To clarify the precise role of HMGB2 on cell proliferation, we did in vitro analysis with expression vectors and small interfering RNAs. RESULTS: HMGB2 mRNA and protein expression were significantly higher in HCC than in noncancerous surrounding tissues (P < 0.0001) and showed a positive correlation (ρ = 0.35, P < 0.001). HMGB2 overexpression was significantly correlated with shorter overall survival time, both at mRNA (P = 0.0054) and protein level (P = 0.023). Moreover, HMGB2 mRNA level was an independent prognostic factor for overall survival in a multivariate analysis (P = 0.0037). HMGB2 knockdown by small interfering RNAs decreased cell proliferation, and overexpression of HMGB2 by expression vectors diminished cisplatin- and etoposide-induced cell death. CONCLUSIONS: Our clinical and in vitro data suggest that HMGB2 plays a significant role in tumor development and prognosis of HCC. These results can partly be explained by altered cell proliferations by HMGB2 associated with the antiapoptotic pathway.

Clinical impact of microsatellite instability in colon cancer following adjuvant FOLFOX therapy.

PURPOSE: Colon cancer with DNA mismatch repair (MMR) defects reveals indistinguishable clinical and pathologic aspects, including better prognosis and reduced response to 5-fluorouracil (5-FU)-based chemotherapy. There has been no consensus for p53 as a prognostic marker in colorectal cancer. This study investigated the clinical implication of MSI-H/MMR-D and p53 expression in R0-resected colon cancer patients who received adjuvant oxaliplatin/5-FU/leucovorin (FOLFOX) therapy. EXPERIMENTAL DESIGN: We analyzed 135 patients, who had been treated by adjuvant chemotherapy containing 5-FU and oxaliplatin (FOLFOX) after curative resection (R0) for colon adenocarcinoma between May 2004 and November 2007. Tumor expression of the MMR proteins, MLH1 and MSH2, was detected by immunohistochemistry (IHC) in surgically resected tumor specimens. MSI was analyzed by polymerase chain reaction (PCR) amplification using fluorescent dye-labeled primers specific for microsatellite loci. Tumors with MMR defects were defined as those demonstrating loss of MMR protein expression (MMR-D) and/or microsatellite instability high (MSI-H) genotype. Expression patterns of p53 were determined in a semiquantitative manner by light microscopy. RESULTS: There were 13 (9.6%) patients with stage II, 108 (80%) with stage III, and 14 (10.4%) with stage IV. Fourteen patients with stage IV (10.3%) had metastases to liver only, all of whom underwent complete metastasectomy for liver metastases. In total, 134 tumor specimens were genotyped, 115 specimens were tested by IHC and 113 cases had both genotyping and IHC results available for analysis. Genotyping results demonstrated that 12 (9.0%) cases were MSI-H and 122 (91.0%) were MSI-L/S. By IHC, 11 (9.6%) patients were MMR-D and 104 (90.4%) were MMR-I. The methods were in agreement in 108 patients (94.7%). We assessed 114 patients for p53 expression by immunostaining. MMR status was not significantly associated with DFS (P = 0.56) or OS (P = 0.61) in patients with colon cancer (n = 135) receiving adjuvant FOLFOX. According to p53 status, there was also no significant difference for DFS (P = 0.11) and OS (P = 0.94). For patients with genotyping/IHC agreement (n = 108), there was no difference in DFS (P = 0.57) and OS (P = 0.98) between patients with MSI-H/MMR-D and MSI-L/S/MMR-I tumors. CONCLUSION: The MMR status or p53 positivity was not significantly associated with outcomes to FOLFOX as adjuvant chemotherapy in colon cancer patients with R0 resection. Adding oxaliplatin in adjuvant chemotherapy may overcome negative impact of 5-FU on colon cancers with MSI-H/MMR-D.