Sensitive assay for detection of hepatocellular carcinoma associated gene transcription (alpha-fetoprotein mRNA) in blood

Development of a Non-Transformed Human Liver Cell Line with Differentiated-Hepatocyte and Urea-Synthetic Functions: Applicable for Bioartificial Liver

There is a need to develop human hepatocyte cell lines which retain both replicating capacity and highly differentiated functions to facilitate the development of an efficient bioartificial liver. The present study was undertaken to differentiate, using sodium butyrate, the actively replicating immortalized human liver cell line.

The effects of butyrate on cell growth and cell cycle were analyzed, and the albumin synthesis, cytochrome P450 and ammonia-detoxifying activity of the butyrate-treated cells were measured. Butyrate treatment resulted in G2/M arrest of the cell cycle and polygonal changes in the cell morphology. Neither the control nor the butyrate-treated cells showed transformed characteristics. Butyrate treatment increased the amount of albumin secretion, cytochrome P450 activity, and the urea production rate of the cells.

The present study provides non-transformed human hepatocytes, which can replicate unlimitedly and then restore differentiated hepatocyte-specific functions by butyrate, and therefore, have applications for the development of an efficient bioartiflcial liver

Circulating tumor cells measurements in hepatocellular carcinoma

Liver cancer is the fifth most common cancer in men and the seventh in women. During the past 20 years, the incidence of HCC has tripled while the 5-year survival rate has remained below 12%. The presence of circulating tumor cells (CTC) reflects the aggressiveness nature of a tumor. Many attempts have been made to develop assays that reliably detect and enumerate the CTC during the development of the HCC. In this case, the challenges are (1) there are few markers specific to the HCC (tumor cells versus nontumor cells) and (2) they can be used to quantify the number of CTC in the bloodstream. Another technical challenge consists of finding few CTC mixed with million leukocytes and billion erythrocytes. CTC detection and identification can be used to estimate prognosis and may serve as an early marker to assess antitumor activity of treatment. CTC can also be used to predict progression-free survival and overall survival. CTC are an interesting source of biological information in order to understand dissemination, drug resistance, and treatment-induced cell death. Our aim is to review and analyze the different new methods existing to detect, enumerate, and characterize the CTC in the peripheral circulation of patients with HCC.

Diagnostic value of cancer-testis antigen mRNA in peripheral blood from hepatocellular carcinoma patients

AIM: To evaluate the diagnostic value of cancer-testis antigen (CTA) mRNA in peripheral blood samples from hepatocellular carcinoma (HCC) patients.

METHODS: Peripheral blood samples were taken from 90 patients with HCC before operation. Expression of melanoma antigen-1 (MAGE-1), synovial sarcoma X breakpoint-1 (SSX-1), and cancer-testis-associated protein of 11 kDa (CTp11) mRNA in peripheral blood mononuclear cells (PBMC) was tested by nested reverse transcripts-polymerase chain reaction (RT-PCR). Serum α-fetoprotein (AFP) in these patients was also determined.

RESULTS: The positive rate of MAGE-1, SSX-1 and CTp11 transcripts was 37.7%, 34.4%, 31.1% in PBMC samples, and 74.4%, 73.3%, 62.2% in their resected tumor samples, respectively. The positive rate for at least one of the transcripts of three CTA genes was 66.7% in PBMC samples and 91.1% in their resected tumor samples. MAGE-1, SSX-1 and/or CTp11 mRNA were not detected in the PBMC of those patients from whom the resected tumor samples were MAGE-1, SSX-1 and/or CTp11 mRNA negative, nor in the PBMC samples from 20 healthy donors and 10 cirrhotic patients. Among the 90 patients, the serum AFP in 44 patients met the general diagnostic standard (AFP > 400 μg/L) for HCC, and was negative (AFP ≤ 20 μg/L) or positive with a low concentration (20 μg/L < AFP ≤ 400 μg/L) in the other patients. The positive rate for at least one of the transcripts of three CTA genes in PBMC samples from the AFP negative or positive patients with a low concentration was 69.2% and 45.0%, respectively. Of the 90 patients, 71 (78.9%) were diagnosed as HCC by nested RT-PCR and serum AFP. Although the positive rate for at least one of the transcripts of three CTA genes in PBMC samples from 53 patients at TNM stage III or IV was obviously higher than that in PBMC samples from 37 patients at stage I or II (77.9% vs 51.4%, P = 0.010), the CTA mRNA was detected in 41.7% and 56.0% of PBMC samples from HCC patients at stages I and II, respectively.

CONCLUSION: Detecting MAGE-1, SSX-1 and CTp11 mRNA in PBMC improves the total diagnostic rate of HCC.

Modification of an in vivo lung metastasis model of hepatocellular carcinoma by low dose N-nitrosomorpholine and diethylnitrosamine

Previously, we established the in vivo lung metastasis model of rat HCC induced by two hepatocarcinogens, diethylnitrosamine (DEN) and N-nitrosomorpholine (NMOR) at a dose of 120 ppm. This model allows us to investigate modifying factors leading to the inhibition of metastasis formation. However, low survival rates made the evaluation of metastasis formation difficult. The current experiments were conducted to modify the experimental protocol to improve survival and to establish a better animal metastasis model. Lower doses of NMOR (80 or 40 ppm in drinking water) were given to F344 rats for 14 weeks after DEN treatment. Survival rates in the 80 ppm group and in the 40 ppm group were 57% and 81%, respectively and these values were significantly higher than that in 120 ppm. Incidences of lung metastasis in the 40 ppm group steadily increased up to 67% by week 36 while that in the 80 ppm increased sharply up to 86% by week 24. Severity of lung metastases in the 40 ppm group at week 36 was mild compared with the 80 ppm group at week 24. In the second experiment, in order to characterize HCC development and lung metastasis in the 40 ppm group, rats given DEN and then followed with 40 ppm NMOR were killed sequentially. Development of HCC was observed at week 14 and reached 100% incidence at week 20. First lung metastatic lesions were evident at week 22, and incidence of lung metastasis reached 100%. Tumor cells were identified in the blood at week 20 by RT-PCR. The current study revealed that 40 ppm NMOR for 14 weeks after DEN treatment developed HCC without lung metastases at week 22, then HCC with a frequent lung metastasis at week 40. Thus, it can be said that this system is a more appropriate model for elucidation of mechanisms of metastasis and also for analysis of factors to inhibit natural metastasis.

Quantitation of alpha-fetoprotein messenger RNA for early detection of recurrent hepatocellular carcinoma: A prospective pilot study

BACKGROUND

Alpha-fetoprotein (AFP) messenger RNA (mRNA) may be a potential marker of the dissemination of hepatocellular carcinoma (HCC) cells into the circulation. The aim of this prospective pilot study was to assess the prognostic value of quantitative levels of AFP mRNA in patients undergoing ablative treatment for HCC.

METHODS

Peripheral blood samples were taken from seven patients before and after treatment for measurement of AFP mRNA levels by reverse-transcriptase polymerase chain reaction (RT-PCR). Patients were treated with percutaneous radiofrequency thermal ablation (n=3) or transarterial chemoembolization (n=4). The level of AFP mRNA in blood was serially determined, and the time course was related to the clinical course and disease outcome. The median duration of follow-up was 14 months (range, 9-16 months).

RESULTS

HCC recurred locally in four patients, and lung metastases developed in two of them. Patients were divided into three groups on the basis of the pre- and post-treatment AFP mRNA status. Group 1 included four patients with consistently high serum AFP and AFP mRNA levels (pre- and post-treatment). These patients developed distant and local recurrence. Group 2 included a patient with serum-negative AFP mRNA and normal AFP levels at entry. Although serum AFP remained within normal range, mean AFP mRNA increased from 10 to 95 copies/microg RNA. This patient had no distant metastases, but his tumor markedly increased in size. In Group 3, AFP mRNA and serum AFP remained within normal range before and after treatment. These two patients did not develop either local or distant metastases during the follow-up period.

CONCLUSIONS

Although this is a small sample size pilot study these findings imply that quantitative measurement of AFP-expressing cells in peripheral blood may serve as a marker of HCC recurrence.

Alpha-fetoprotein (AFP)- and des-gamma-carboxy prothrombin (DCP)-producing adenocarcinoma of the stomach with liver metastasis in a patient with chronic hepatitis C

A 45-year-old man was admitted to our hospital because of chronic hepatitis C and a large liver tumor accompanied by increased serum levels of alpha-fetoprotein (AFP) and des-gamma-carboxy prothrombin (DCP), the tumor markers for hepatocellular carcinoma. Endoscopic examination revealed advanced gastric cancer. Biopsy specimens of the stomach and liver showed gastric adenocarcinoma and its metastasis to the liver. Immunohistochemical studies demonstrated that adenocarcinoma cells both of the stomach and liver, were positive for the antibodies against AFP as well as DCP. Expression of AFP mRNA was shown in the cancer cells of the stomach. Accordingly, we diagnosed this patient with AFP- and DCP-producing adenocarcinoma of the stomach together with liver metastasis.

Does the presence of circulating hepatocellular carcinoma cells indicate a risk of recurrence after resection?

OBJECTIVES

Alpha-fetoprotein messenger RNA (AFP mRNA) in the peripheral blood (PB) of patients with hepatocellular carcinoma (HCC) has been considered to represent isolated tumor cells. We investigated its association with the prognosis after curative resection.

METHODS

Using a reverse-transcription polymerase chain reaction (RT-PCR)-based assay, AFP mRNA in the PB was determined prospectively in control and in 81 patients with curative resection for HCC.

RESULTS

Twenty-two (27.2%) and 19 (23.4%) of 81 HCC patients had AFP mRNA in their pre- and postoperative PB. Its presence preoperatively was not associated with an increased risk of HCC recurrence (54.5% vs 40.7%, p= 0.264). In contrast, the postoperative presence associated significantly with a higher incidence of recurrence (89.5% vs 30.6%, p < 0.001), irrespective of preoperative status. The odds ratio for HCC recurrence was 19.2 (95% confidence interval [CI]: 4.0- 91.7). The cmulative probability of recurrence-free survival was also much lower in patients with postoperatively positive AFP mRNA (p < 0.001). The Cox proportional hazards model also demonstrated a significant association with recurrence (p= 0.002). Preoperative serum AFP is also a significant factor and combination with postoperative AFP mRNA enhances the predictability, sensitivity (75.0%), specificity (93.3%), positive prediction (90.0%), and negative prediction (82.4%).

CONCLUSIONS

The postoperative detection of AFP mRNA in PB is associated with an increased risk of earlier HCC recurrence. Combination with preoperative serum AFP is useful in predictability.

Does surgical resection of hepatocellular carcinoma accelerate cancer dissemination

AIM: This study was to investigate whether surgery could increase cancer dissemination and postoperative recurrence in patients with hepatocellular carcinoma (HCC) by detection of human αfetoprotein messenger RNA (hAFP mRNA). hAFP mRNA in the peripheral blood of patients with HCC has been considered as a surrogate marker for circulating tumor cells.

METHODS: Eighty-one consecutive patients who underwent curative resection for HCC entered this prospective cohort study. We examined hAFP mRNA from the peripheral blood obtained preoperatively, perioperatively, and postoperatively to correlate the prognosis after curative resections from HCC patients and from the control subjects. Detection of hAFP mRNA by reverse transcriptase and polymerase chain reaction amplification (RT-PCR) was performed with primers specifically. The relations between the clinical variables (age, sex, associated liver cirrhosis, hepatitis B virus infection, hepatitis C virus infection, serum α-fetoprotein and Child-Pugh class), the histological variables (size, capsule, vascular permeation, grade of differentiation, and daughter nodules), hAFP mRNA in peripheral blood of 3 different sessions, and postoperative course (recurrence, and recurrence related death) were analysed.

RESULTS: No hAFP mRNA was detected in control group subjects. Twenty-two (27%), 24 (30%) and 19 (23%) of 81 HCC patients had hAFP mRNA positivity in the preoperative, perioperative and postoperative peripheral blood. The preoperative presence did not influence the risk of HCC recurrence (55% vs 41%, P = 0.280). In contrast, patients with postoperative presence had a significantly higher recurrence (90% vs 31%, P < 0.001; odds ratio 19.2; 95% confidence interval: 4.0-91.7). In the multivariate analysis by COX proportional hazards model, postoperative positivity had a significant influence on recurrence (P = 0.067) and recurrence related mortality (P = 0.017). Whereas, the perioperative positivity of hAFP mRNA did not increase HCC recurrence (58% vs.39%, P = 0.093). The correlation between perioperative hAFP mRNA positivity and recurrence related mortality had no statistical significance (P = 0.836).

CONCLUSION: From our study, perioperative detection of hAFP mRNA in peripheral blood of patients has no clinical relevance and significant role in the prediction of HCC recurrence. Surgical resection itself may not accelerate cancer dissemination and does not increase postoperative recurrence significantly either.

alpha-Fetoprotein mRNA in the circulation as a predictor of postsurgical recurrence of hepatocellular carcinoma: a prospective study

alpha-fetoprotein (AFP) messenger RNA (mRNA) has been proposed as a marker of hepatocellular carcinoma (HCC) cells disseminated into the circulation, but its clinical significance remains controversial. We prospectively assessed the prognostic value of AFP mRNA in patients undergoing curative hepatic resection for HCC. Peripheral blood samples were taken from 87 patients before and after surgery to determine the presence of AFP mRNA by use of a reverse-transcription polymerase chain reaction. A primary endpoint was recurrence-free interval. AFP mRNA was detectable preoperatively in 31 patients (36%) and postoperatively in 30 patients (34%). With a median follow-up period of 28 months (range, 3-41 months), HCC recurred in 46 patients (53%). Among 4 groups separated according to preoperative and postoperative AFP mRNA status, patients with consistent positivity of AFP mRNA showed the highest recurrence rate (85%) and trend to distant or multiple recurrence. The recurrence-free interval was significantly shorter in patients with postoperative positivity of AFP mRNA than in those without (53% [95% CI, 36-71] vs. 88% [95% CI, 79-96] at 1 year, 37% [95% CI, 17-57] vs. 60% [95% CI, 46-75] at 2 years; P =.014), whereas the preoperative positivity of AFP mRNA provided no significance (P =.100). Cox's proportional-hazards model identified the postoperative positivity of AFP mRNA as an independent prognostic factor for HCC recurrence (relative risk, 2.33; 95% CI, 1.26-4.34; P =.007). In conclusion, postsurgical recurrence of HCC can be predicted by detecting AFP mRNA-expressing cells in peripheral blood.

Polymerase chain reaction in the detection of circulating tumour cells in peripheral blood of melanoma patients

Conflicting results were obtained by various research groups using the tyrosinase reverse transcription polymerase chain reaction (RT-PCR) for detecting melanoma cells circulating in peripheral blood. Whereas 100% positivity was initially reported for stage IV patients, more recent investigations reported positive detection rates between 30% and 50% in patients with disseminated melanoma. While the high detection rate initially reported in metastatic melanoma may be explained by contamination problems, methodological differences in different steps of the technical procedure of RT-PCR may account for the differences reported in more recent examinations. Major differences may result from the kind of blood preparation, the RNA isolation method, the kind of RT enzyme used, and the gene targeted by PCR primers. In our experience, blood purification by a Ficoll gradient increased melanoma cell detection rates compared to RNA extraction from total blood or after erythrocyte lysis. Amplification of MelanA in addition to tyrosinase resulted in a 30% enhanced sensitivity of melanoma cell detection compared to amplification to tyrosinase alone, whereas gp100/pMel17 and MUC18 gene products were already detected in blood from nonmelanoma patients. These findings are in agreement with those of other groups. Currently, an increase in the sensitivity for detection of circulating tumour cells to more than 50% of patients with disseminated melanoma seems to be unlikely. It is interesting that between 15% and 30% positive results and sometimes more have already been obtained from patients with primary melanoma. So far, there is no data for judging the prognostic significance of the detection of circulating tumour cells in patients without clinically recognisable metastases. Our limited experience shows that staging examinations in these patients reveal no proof of macrometastasis. Therefore, it is presently unclear whether these positive findings are associated with long-term prognosis or if they merely reflect false positive findings in this highly sensitive RT-PCR technique.

Detection of circulating testicular cancer cells in peripheral blood

Patients who receive peripheral blood stem cell transplants are at risk of developing cancer recurrence due to the presence of malignant cells in the transplants. We investigated a sensitive method to detect malignant cells in the peripheral blood and peripheral blood stem cells of patients with testicular cancer using nested, reverse transcription-polymerase chain reaction (RT-PCR) to measure alpha-fetoprotein gene expression. Using this technique, a single cancer cell could be detected in 10(6) peripheral blood mononuclear cells. This is the first report of an attempt to detect circulating malignant cells in the peripheral blood of patients with testicular cancer by nested RT-PCR.

Presence of alpha-fetoprotein mRNA in blood correlates with outcome in patients with hepatocellular carcinoma

BACKGROUND/AIMS

Since hematogenous spread of tumor cells may adversely affect the prognosis of patients with hepatocellular carcinoma, we prospectively analyzed whether the presence of alpha-fetoprotein (AFP) messenger RNA (mRNA) in blood, used as a marker of circulating hepatocellular carcinoma cells, correlates with outcome.

METHODS

Eighty-eight patients were enrolled between December 1993 and August 1995, and 81 were followed until the end of 1997. All patients were treated with percutaneous ethanol injection therapy and/or transarterial embolization during follow-up. The status of AFP mRNA in blood was serially determined. Cumulative metastasis-free survival and overall survival were analyzed in relation to AFP mRNA and other clinical and laboratory variables.

RESULTS

Among 81 patients followed, 54 were positive for AFP mRNA at entry and 27 were negative. Extrahepatic metastasis developed more frequently among the AFP mRNA-positive patients (13 of 54) than among the AFP mRNA-negative patients (2 of 27) (p=0.0296). After treatment, AFP mRNA became negative in 24 of 54 patients (44%). Cumulative metastasis-free survival and overall survival were significantly better in the 24 patients whose AFP mRNA became negative after treatment than in the 30 patients with persistently positive AFP mRNA (p= 0.0001 and p<0.0001, respectively).

CONCLUSIONS

The presence or absence of AFP mRNA in blood is a predictor of outcome in patients with hepatocellular carcinoma.

Amplification of MelanA messenger RNA in addition to tyrosinase increases sensitivity of melanoma cell detection in peripheral blood and is associated with the clinical stage and prognosis of malignant melanoma

An improved protocol for reverse transcription-polymerase chain reaction (RT-PCR), amplifying tyrosinase and MelanA/MART-1 mRNA from peripheral blood, was used to test 340 blood samples from 225 patients with malignant melanoma for the presence of circulating tumour cells. Positive results for tyrosinase or MelanA were obtained in 19% of patients in stage I (n = 74), 31% in stage II (n = 45), 29% in stage III (n = 48) and 52% in stage IV (n = 58). Amplification of MelanA in addition to tyrosinase resulted in a 30% enhanced sensitivity of melanoma cell detection compared with amplification of tyrosinase alone. The sensitivity was further enhanced by analysis of at least two blood samples per patient and performing at least two PCR analyses per sample. During a median follow-up of 4 months, patients with a positive PCR showed a 2. 4-fold increased risk for relapse compared with PCR-negative patients. These data indicate that the detection of circulating melanoma cells in peripheral blood using our optimized protocol for RT-PCR correlated with the clinical stage of disease and is therefore likely to be a prognostic marker for recurrence. MelanA is a sensitive additional marker to tyrosinase in detecting micrometastases using RT-PCR.

Role of alpha-fetoprotein in the diagnosis and management of hepatocellular carcinoma

Thirty-five years after its first description, alpha-fetoprotein (AFP) remains the gold standard by which other markers are judged. Serum levels above the reference range of 10 ng/mL occur in approximately 75% of cases of hepatocellular carcinoma (HCC). In individual patients, the serum AFP level behaves as if it reflects tumour mass. However, the specificity of AFP is relatively low because moderately raised levels are also found in some patients with uncomplicated chronic liver disease. Recently, tumour-specific AFP assays have been developed. These are based on the carbohydrate side-chains on the AFP molecule which exhibit characteristic differences in AFP of different origins. Monitoring response to treatment may often be more effectively carried out by serial estimation of AFP than by conventional imaging techniques. The relative specificity of AFP for HCC has also been employed to detect circulating HCC cells and to target gene therapy.

Perioperative change in albumin messenger RNA levels in patients with hepatocellular carcinoma

A quantitative assay of albumin messenger RNA (mRNA) in blood samples was designed using the competitive reverse-transcription polymerase chain reaction, and the significance of measuring albumin mRNA levels in the blood of patients with hepatocellular carcinoma (HCC) in hepatic resection was evaluated. Albumin mRNA levels were measured in the following: (1) peripheral blood in 11 patients with HCC and 20 control subjects without liver disease, (2) blood in the portal and hepatic veins in five patients with HCC immediately after laparotomy, and (3) a perioperative series of peripheral blood in eight patients with HCC. Two patients with HCC whose albumin mRNA level in peripheral blood was markedly high were both at stage IVa. On the other hand, 20 control subjects showed negative or <5 x 10(3) transcripts/microgram RNA of albumin mRNA expression. Immediately after laparotomy, the albumin mRNA levels in the tumor-draining hepatic vein were greater than in the portal and non-tumor-draining hepatic veins in four of five patients with HCC. Albumin mRNA levels in peripheral blood showed a marked increase after mobilization and/or resection of the liver and, thereafter, gradually decreased at postoperative day 7 in all eight patients with HCC. A new method to measure the albumin mRNA levels in blood samples was developed, and high albumin mRNA levels in the peripheral blood of patients with advanced-stage HCC suggest the presence of HCC cells in the circulation. Increased levels in the tumor-draining hepatic vein could indicate the spontaneous release of tumor cells or nontumorous hepatocytes or an increased albumin transcription in activated blood mononuclear cells. An increase in the levels in peripheral blood during an operation is intermittent. Therefore, an increased albumin mRNA level in the tumor-draining vein suggests, but does not prove, that the increased albumin mRNA level reflects tumor cells entering the systemic circulation. This alone does not prove that the prognosis is worsened.

Expression of uroplakin Ib and uroplakin III genes in tissues and peripheral blood of patients with transitional cell carcinoma

Uroplakins (UPs), urothelium-specific transmembrane proteins, are present only in urothelial cells. We have determined the nucleotide sequences of human UP-Ib and UP-III and synthesized specific primer pairs. The two UP genes were expressed in both cancerous and noncancerous urothelial taken from all patients examined by reverse transcription-polymerase chain reaction (RT-PCR). These genes were also detected in the peripheral blood of 3 patients with metastatic transitional cell carcinoma (TCC), but not in that from 9 patients with non-metastatic TCC or 3 healthy volunteers. The sensitivity of our assay was sufficient to detect one cancer cell in 5 ml of peripheral blood. Detection of UP gene-expression in blood by RT-PCR may provide helpful information for the diagnosis and management of TCC.

Utilization of polymerase chain reaction technology in the detection of solid tumors

BACKGROUND

Most cancer detection tests currently performed are based on either antibody assays to a marker protein with altered expression in cancer patients or on imaging studies to identify characteristic lesions. Generally, for a positive result, these detection assays require that a tumor have a significant volume of cancer cells. Advances in diagnostic techniques and technology may allow for cancer detection at earlier stages, when the tumor burden is smaller and potentially more curable. The molecular techniques of polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) are highly sensitive methods for detecting a small number of cancer cells. Over the past few years, numerous clinical studies have used PCR techniques to detect physical alterations of genes, such as mutations, deletions, translocations and amplification, the presence of oncogenic viruses, and the expression of genes specific to tissue, cancer, and metastasis. The current status of PCR as a method for detecting marker genes in the management of solid tumors is reviewed.

METHODS

A review of the literature on the clinical utility of PCR and RT-PCR in the detection of solid tumor micrometastasis was conducted.

RESULTS

Amplification by PCR is a highly sensitive method to determine gene expression. A single cell expressing a tumor marker among 10-100 million lymphocytes can be detected by the PCR assay. This approach has been used to detect tumor cells in approximately 18 different solid tumor types, with melanoma and carcinoma of the breast and prostate the most widely investigated to date. PCR-based assays have been used to detect cancer cells in biopsies of solid tissue, lymph nodes, bone marrow, peripheral blood, and other body fluids. Several studies have reported a high specificity and sensitivity of tumor marker detection and a high correlation between PCR results and the presence of metastatic disease. However, in a few studies, PCR assays have not consistently demonstrated a higher sensitivity and specificity of detection than traditional modalities for many types of cancer. There has been a wide range in sensitivity and specificity among the studies, which may be partly attributed to the lack of uniformity among the PCR protocols used in different studies.

CONCLUSIONS

PCR can detect tumor marker-expressing cells that are otherwise undetectable by other means in patients with localized or metastatic cancer. Reports from various study groups have lacked uniformity in their protocols, and this has prevented adequate comparison. The clinical utility of this assay as a tool for the prognosis and management of cancer patients remains and area of active investigation. PCR is a powerful tool in the study of the biology of cancer metastasis and will likely serve as a useful adjunct to clinical decision-making in the future.

Detection of hepatoma cells in peripheral blood of HCC patients by nested RT-PCR

AIM: To offer a more simple method with a high sensitivity and specificity for detection of hepatoma cells in peripheral blood of the patients with HCC.

METHODS: Improved nested RT-PCR method was used to detect the expression of AFP mRNA in nuclear cells separated from peripheral venous blood.

RESULTS: AFP mRNA contained in ten hepatoma cells was detected from 2 mL peripheral blood.

CONCLUSION: The improved nested RT-PCR assay for AFP mRNA expressed in cancer cells in peripheral blood might be a valuable method for clinical diagnosis of HCC.

Utilization of polymerase chain reaction technology in the detection of solid tumors

BACKGROUND

Most cancer detection tests currently performed are based on either antibody assays to a marker protein with altered expression in cancer patients or on imaging studies to identify characteristic lesions. Generally, for a positive result, these detection assays require that a tumor have a significant volume of cancer cells. Advances in diagnostic techniques and technology may allow for cancer detection at earlier stages, when the tumor burden is smaller and potentially more curable. The molecular techniques of polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) are highly sensitive methods for detecting a small number of cancer cells. Over the past few years, numerous clinical studies have used PCR techniques to detect physical alterations of genes, such as mutations, deletions, translocations and amplification, the presence of oncogenic viruses, and the expression of genes specific to tissue, cancer, and metastasis. The current status of PCR as a method for detecting marker genes in the management of solid tumors is reviewed.

METHODS

A review of the literature on the clinical utility of PCR and RT-PCR in the detection of solid tumor micrometastasis was conducted.

RESULTS

Amplification by PCR is a highly sensitive method to determine gene expression. A single cell expressing a tumor marker among 10-100 million lymphocytes can be detected by the PCR assay. This approach has been used to detect tumor cells in approximately 18 different solid tumor types, with melanoma and carcinoma of the breast and prostate the most widely investigated to date. PCR-based assays have been used to detect cancer cells in biopsies of solid tissue, lymph nodes, bone marrow, peripheral blood, and other body fluids. Several studies have reported a high specificity and sensitivity of tumor marker detection and a high correlation between PCR results and the presence of metastatic disease. However, in a few studies, PCR assays have not consistently demonstrated a higher sensitivity and specificity of detection than traditional modalities for many types of cancer. There has been a wide range in sensitivity and specificity among the studies, which may be partly attributed to the lack of uniformity among the PCR protocols used in different studies.

CONCLUSIONS

PCR can detect tumor marker-expressing cells that are otherwise undetectable by other means in patients with localized or metastatic cancer. Reports from various study groups have lacked uniformity in their protocols, and this has prevented adequate comparison. The clinical utility of this assay as a tool for the prognosis and management of cancer patients remains and area of active investigation. PCR is a powerful tool in the study of the biology of cancer metastasis and will likely serve as a useful adjunct to clinical decision-making in the future.

Detection and characterization of carcinoma cells in the blood

A highly sensitive assay combining immunomagnetic enrichment with multiparameter flow cytometric and immunocytochemical analysis has been developed to detect, enumerate, and characterize carcinoma cells in the blood. The assay can detect one epithelial cell or less in 1 ml of blood. Peripheral blood (10-20 ml) from 30 patients with carcinoma of the breast, from 3 patients with prostate cancer, and from 13 controls was examined by flow cytometry for the presence of circulating epithelial cells defined as nucleic acid+, CD45(-), and cytokeratin+. Highly significant differences in the number of circulating epithelial cells were found between normal controls and patients with cancer including 17 with organ-confined disease. To determine whether the circulating epithelial cells in the cancer patients were neoplastic cells, cytospin preparations were made after immunomagnetic enrichment and were analyzed. Epithelial cells from patients with breast cancer generally stained with mAbs against cytokeratin and 3 of 5 for mucin-1. In contrast, no cells that stained for these antigens were observed in the blood from normal controls. The morphology of the stained cells was consistent with that of neoplastic cells. Of 8 patients with breast cancer followed for 1-10 months, there was a good correlation between changes in the level of tumor cells in the blood with both treatment with chemotherapy and clinical status. The present assay may be helpful in early detection, in monitoring disease, and in prognostication.

Clinical usefulness of RT-PCR detection of hematogenous prostate cancer spread

Understaging is commonly associated with therapeutic failure of surgical intervention in apparently localized prostate cancers. Methods that specifically detect prostate cancer cells in the circulation may be able to identify metastatic cancers and thus aid in the selection of the most adequate therapy. The high sensitivity and specificity of the reverse transcriptase-polymerase chain reaction (RT-PCR) encouraged various groups to investigate the mRNA expression of prostate-specific markers in the peripheral blood of patients with prostate cancer. However, probably due to methodological differences, many contradictory results have been obtained with the markers studied so far: prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSM). For this reason, clinical decisions should not be based yet on RT-PCR results. Future research and long-term follow-up on the patients may point out whether RT-PCR assays, following appropriate standardization, will have an additive value in prostate cancer staging and in prediction of tumor progression.

Prospective evaluation of circulating hepatocytes by alpha-fetoprotein mRNA in humans during liver surgery

OBJECTIVE

The objective of this study was to analyze the specificity of detecting liver tumor cell dissemination by alpha-fetoprotein (AFP) mRNA in peripheral blood.

SUMMARY BACKGROUND DATA

Alpha-fetoprotein mRNA has been used for the detection of circulating micrometastatic tumor foci of hepatocellular carcinoma (HCC); however, the interpretation of the results has been equivocal.

METHODS

Sixty-four consecutive patients with malignant HCC (n = 20), liver metastases (n = 27), or nonmalignant (n = 17) liver diseases undergoing partial or total hepatectomy and orthotopic liver transplantation were included in this prospective study from January to July 1995. Peripheral blood samples were obtained before surgery, during surgery, and after surgery (range, 6-15 months). Total mRNA was extracted from nucleated cells, and cDNA synthesis and polymerase chain reaction amplification (nested polymerase chain reaction in one tube) were performed with specific AFP primers.

RESULTS

Preoperative AFP mRNA was detected in 20 patients (17%), of which 5 of 20 had HCC. Intraoperative assessment showed positive AFP mRNA values in a total of 34 patients (53%) with various causes, of which 8 of 20 (40%) had HCC, 17 of 27 (63%) had other malignancies, and 9 of 17 (53%) had nonmalignant diseases. Recurrent tumor in patients with HCC occurred in four cases after surgery (range, 6-15 months) and did not correlate with AFP mRNA positivity before surgery, during surgery, or after surgery.

CONCLUSIONS

Alpha-fetoprotein mRNA in peripheral blood is not a specific marker of circulating micrometastases from HCC, especially in the context of surgical treatment of HCC.

Semiquantification of circulating hepatocellular carcinoma cells by reverse transcriptase polymerase chain reaction

Hepatocellular carcinoma (HCC) is one of the most common and rapidly fatal malignancies worldwide. Treatment options are severely limited by the frequent presence of metastases. If hepatocyte-specific mRNAs are detected in the circulation, it is possible to infer the presence of circulating, presumably malignant, liver cells. If these can be quantified, it is possible to predict the likelihood of haematogenous metastasis. In this investigation, we have attempted to gain an index of the mass of circulating HCC cells (with reference to the number of hepatoblastoma cells) by measuring the amounts of PCR products for albumin (alb) mRNA and alpha-fetoprotein (afp) mRNA by reverse transcriptase polymerase chain reaction (RT-PCR) and Southern blot analysis. For calibration, total RNA from 1-10(6) HepG2 cells was mixed with total RNA from 10(6) normal peripheral mononuclear cells. A linear relationship was demonstrated between the amount of alb- or afp PCR product and the level of HepG2 total RNA spiked. The assay is sensitive down to a detection level of one HepG2 cell. Alb mRNA was detected in 50% of 18 normal subjects and afp mRNA in only two normal subjects. The alb mRNA cut-off level for the normal was exceeded by seven normal subjects and 34 out of 64 HCC patients, and that for afp mRNA was exceeded by six HCC patients but none of the normal subjects. The level of alb mRNA detected was not linearly proportional to the amount of afp mRNA detected in peripheral blood of the same patients, suggesting heterogeneous expression of alb and afp genes in different circulating tumour cells. In addition, no significant linear association between the levels of afp mRNA and serum AFP was observed. Semiquantification of both mRNA markers for HCC cell detection may prove useful in prediction of metastases.

Detection of circulating albumin-mRNA by RT-PCR does not indicate metastasizing hepatocellular carcinoma

Hepatocellular carcinomas (HCC) frequently recur after partial liver resection or orthotopic liver transplantation, possibly because of the presence of a small number of hepatoma cells in the peripheral blood. Detection of circulating HCC cells might improve therapeutic options and could predict disease recurrence resulting from a metastasizing disease. In the present study, human albumin-mRNA was detected by RT-PCR in the peripheral blood of patients with hepatocellular carcinoma. Circulating albumin-specific PCR products were detected in each patient with HCC, but also in healthy volunteers. It is concluded that albumin-mRNA is not specific to circulating hepatoma cells and therefore does not indicate metastasizing disease.

Detection of alphafetoprotein-expressing cells in the blood of patients with hepatoma and hepatitis

The presence of tumour cells in the blood circulation may predict disease recurrence and metastasis. We have evaluated the specificity and sensitivity of detecting hepatoma cells in blood using nested polymerase chain reaction with primers specific for the alphafetoprotein (AFP) gene. The nested polymerase chain reaction amplified a 270-base pair AFP DNA fragment from cDNA of Hep 3B hepatoma cells. In a reconstitution experiment, AFP mRNA was detected from peripheral mononuclear cells isolated from 10 ml of blood containing as few as ten Hep 3B cells. Peripheral mononuclear cells from the blood of 20 hepatoma patients were analysed, and 19 patients showed positive AFP mRNA expression. Seven of 13 samples from hepatitis patients also showed positive AFP mRNA expression. All five paired samples of peripheral blood or umbilical cord blood from pregnant mothers and their babies, respectively, showed positive AFP expression. None of 22 control samples was positive. The presence of AFP mRNA in the blood of hepatitis or hepatoma patients suggests the presence of circulating hepatoma cells or hepatocytes in the circulation. The high incidence of AFP mRNA in the blood of hepatoma patients supports the notion of early haematogenous spreading of the disease.