Low-dose 5-fluorouracil (5-FU), a widely used chemotherapeutic, has been reported to have immunomodulatory effects. This study aimed to evaluate the optimal dose of 5-FU that produces antitumor and immunomodulatory effects. In a hepatoma 22 tumor-bearing mouse model, 0, 10, 20 and 40 mg/kg 5-FU (i.p.) was administered for 10 days. Tumor weight and volume were measured, thymus index (TI) and spleen index (SI) were calculated, and the number of white blood cells (WBCs) and lymphocytes (LYs) were counted following treatment. The percentages of CD3+, CD4+, CD8+ and natural killer (NK) cells were measured by flow cytometry. In addition, the body weights of the mice were measured and the average diet consumption was calculated. Administration of 5-FU produced a potent antitumor effect in a dose-dependent manner (P<0.01). At 20 and 40 mg/kg, a significant reduction of body weight and food consumption was observed. TI and SI decreased in the 20- and 40-mg/kg groups (P<0.01) for 10 days. The number of WBCs significantly decreased in each group (P<0.01); however, the number of LYs only decreased in the 40-mg/kg group (P<0.01). Percentages of CD3+ and CD4+ cells were increased in the 10- and 20-mg/kg groups (P<0.01). Thus, 5-FU at 10 mg/kg inhibits tumor growth while maintaining the immune function of the mice. 5-FU may exert its antitumor effect at a low dose with low toxicity and stimulate the host immune system. Future clinical trials taking into account the immunostimulatory capacity of chemotherapeutic agents are desirable for certain patients.

BACKGROUND/OBJECTIVESA variety of immunomodulators can improve the efficacy of low-dose chemotherapeutics. Active hexose correlated compound (AHCC), a mushroom mycelia extract, has been shown to be a strong immunomodulator. Whether AHCC could enhance the antitumor effect of low-dose 5-fluorouracil (5-FU) via regulation of host immunity is unknown.MATERIALS/METHODSIn the current study Hepatoma 22 (H22) tumor-bearing mice were treated with PBS, 5-FU (10 mg·kg-1·d-1, i.p), or AHCC (360 mg·kg-1·d-1, i.g) plus 5-FU, respectively, for 5 d. CD3+, CD4+, CD8+, and NK in peripheral blood were detected by flow cytometry. ALT, AST, BUN, and Cr levels were measured by biochemical assay. IL-2 and TNFα in serum were measured using the RIA kit and apoptosis of tumor was detected by TUNEL staining. Bax, Bcl-2, and TS protein levels were measured by immunohistochemical staining and mRNA level was evaluated by RT-PCR.RESULTSDiet consumption and body weight showed that AHCC had no apparent toxicity. AHCC could reverse liver injury and myelosuppression induced by 5-FU (P < 0.05). Compared to mice treated with 5-FU, mice treated with AHCC plus 5-FU had higher thymus index, percentages of CD3+, CD4+, and NK cells (P < 0.01), and ratio of CD4+/CD8+ (P < 0.01) in peripheral blood. Radioimmunoassay showed that mice treated with AHCC plus 5-FU had the highest serum levels of IL-2 and TNFα compared with the vehicle group and 5-FU group. More importantly, the combination of AHCC and 5-FU produced a more potent antitumor effect (P < 0.05) and caused more severe apoptosis in tumor tissue (P < 0.05) compared with the 5-FU group. In addition, the combination of AHCC and 5-FU further up-regulated the expression of Bcl-2 associated X protein (Bax) (P < 0.01), while it down-regulated the expression of B cell lymphoma 2 (Bcl-2) (P < 0.01).CONCLUSIONSThese results support the claim that AHCC might be beneficial for cancer patients receiving chemotherapy.

Background Liver metastasis is a common cause of death from colorectal cancer (CRC). In this paper we developed a liver metastasis mouse model by microsurgical orthotopic implantation (MSOI) to illuminate the CRC progression with an eye toward developing effective drug treatment. Methods Murine colon carcinoma CT-26 cells were cultured and then injected to male BALB/c athymic nude mice right flank to generate subcutaneous implantation tumor with 2×10 7 CT-26 cell suspension in DMEM. Tumor tissue at an average size of 1 cm 3 was injected into another nude mice right flank with 20-gauge inoculating needle. Between fourth and sixth generations, tumor tissue sewn into the cecal surface establishes orthotopic transplanted CRC model by MSOI. Then on the 7th, 14th, 21st and 35th day, body weight, abdomen circumference, volume of ascites and local tumor weight were observed and weighed. On the 21st day and 35th day, local tumor rate was calculated, and metastatic tumors of other organs were observed. Tumor tissue was stained by HE for pathologic analysis. Results On the 35th day, body weight and abdomen circumference of the model group were significantly higher than the control group (P<0.01). Local tumor weight increased rapidly from the 21st d to the 35th d (P<0.01), and take rate was high (100%). Metastatic tumor appeared only in liver on the 21st day and then invaded to liver, stomach, retroperitoneal lymph node and abdominal wall on the 35th day. The metastatic rate of liver tumor respectively was 83.3% and 100% on the 21st day and 35th day, but liver function remained normal. Pathologic analysis showed that colorectal tumor invaded the normal tissue of liver, abdominal wall and stomach. Conclusions A stable hepatic metastasis mouse model of murine CRC was established by MSOI.

The multiplex polymerase chain reaction (PCR) technique was applied to detect the SARS-CoV (severe acute respiratory syndrome-associated coronavirus) specific target cDNA fragments in the present study. The target cDNA fragments of SARS-CoV were synthesized artificially according to the genome sequence of SARS-CoV in GenBank submitted by The Chinese University of Hong Kong, and were used as simulated positive samples. Five primers recommended by World Health Organization (WHO) were used to amplify the fragments by single PCR and multiplex PCR. Three target cDNA fragments (121, 182 and 302 bp), as well as the three different combinations of any two of these fragments, were amplified by single PCR. The combination of these three fragments was amplified by multiplex PCR. The results indicated that the multiplex PCR technique could be applied to detect the SARS-CoV specific target cDNA fragments successfully.