Bufalin is a key component of a Chinese medicine (Chan Su) and has been proved effective in killing various cancer cells. Its role in inducing DNA damage and the inhibition of the DNA damage response (DDR) has been reported, but none have studied such action in lung cancer in detail. In this study, we demonstrated bufalin-induced DNA damage and condensation in NCI-H460 cells through a comet assay and DAPI staining, respectively. Western blotting indicated that bufalin suppressed the protein levels associated with DNA damage and repair, such as a DNA dependent serine/threonine protein kinase (DNA-PK), DNA repair proteins breast cancer 1, early onset (BRCA1), 14-3-3 σ (an important checkpoint keeper of DDR), mediator of DNA damage checkpoint 1 (MDC1), O6-methylguanine-DNA methyltransferase (MGMT) and p53 (tumor suppressor protein). Bufalin could activate phosphorylated p53 in NCI-H460 cells. DNA damage in NCI-H460 cells after treatment with bufalin up-regulated its ATM and ATR genes, which encode proteins functioning as sensors in DDR, and also up-regulated the gene expression (mRNA) of BRCA1 and DNA-PK. But bufalin suppressed the gene expression (mRNA) of p53 and 14-3-3 σ, however, bufalin did not significantly affect the mRNA of MGMT. In conclusion, bufalin induced DNA damage in NCI-H460 cells and also inhibited its DNA repair and checkpoint function.

Administration of interferons (IFN) via the intranasal route recently has been shown to exert an antitumor activity against a variety of tumors in mice, including B16 melanoma inoculated intravenously. This study confirms the antitumor activity of orally administered IFN-alpha against B16 melanoma challenge using another route of tumor inoculation, the intraperitoneal route. It further demonstrates that orally administered IFN-alpha can synergistically interact with intraperitoneally administered IFN-gamma but not with intraperitoneally administered IFN-alpha. The results support the interpretation that the oral route may provide an effective alternative or supplement to current methods of IFN administration for the control of malignancies.

Vaccination using inactivated B16 melanoma cells that have been treated in vitro for > 2 weeks with interferon-alpha (IFN-alpha) (B16alpha cells) has been shown to elicit a protective host antitumor immunity. In these studies, vaccination with B16alpha cells has been shown to provide protection against primary B16 tumor challenge, established B16 tumors, and metastatic B16 tumors. Specific immune cells and factors that might mediate this tumor immunity have now been evaluated. Macrophage depletion studies suggest that macrophage function is required for expression of tumor immunity either for processing of antigen or for cytokine production but that macrophage function is not involved in direct cytotoxicity against the B16 challenge tumor. CD8(+) T cell depletion studies show that cytotoxic T cell function is required for expression of tumor immunity. Syngeneic knockout mouse experiments offer further insights into the immune cells and factors that mediate the development and expression of tumor immunity. First, interleukin-12 (IL-12) knockout mouse experiments identify IL-12 as an important cytokine in mediating the development of tumor immunity. Second, specific knockout mouse experiments show that tumor immunity requires the function of CD4(+) T cells, CD8(+) T cells, and natural killer (NK) cells. Third, specific knockout mouse experiments show that tumor immunity does not require the function of B cells. The results suggest that vaccination with inactivated B16alpha cells induces an active, cell-mediated immunity to B16 melanoma cells. The tumor vaccination protocol with B16alpha cell vaccinations establishes a potent tumor immunity against B16 melanoma tumors in mice and may serve as a model for induction of tumor immunity against primary or secondary melanoma tumors in humans.

B16 melanoma cells exposed to >2 weeks of in vitro interferon-alpha (IFN-alpha) treatment (B16alpha cells) were UV inactivated and used for vaccination. This vaccination was efficacious against challenge with parental B16 cells in the absence of adjuvant therapy. Vaccinations based on parental cells and B16 cells exposed to short-term in vitro IFN-alpha treatment were not effective. The efficacy of B16alpha vaccination was evaluated using three B16 tumor models. Using intraperitoneal (i.p.) tumor challenge given after vaccination, vaccination efficacy depended on the concentration of IFN-alpha to which B16alpha cells were exposed, the number of inactivated B16alpha cells inoculated, the number of inoculations administered, and the amount of tumor burden. A significant fraction (30%) of vaccinated mice surviving initial challenge had durable immunity against a second parental tumor challenge. This immunity increased to 92% with administration of a single booster vaccination. Using metastatic tumor challenge given after vaccination, vaccination reduced lung metastases by approximately 67%. Using vaccination begun 3 days after subcutaneous (s.c.) tumor challenge, regression of established tumor occurred when vaccination was given i.p. (39%) or contralaterally s.c. (53%). Taken together, the results suggest that vaccination with inactivated B16alpha cells may serve as a model for induction of host tumor immunity against primary or secondary tumors.

The aims of the present study were to assess the effect of the quartz particle size on XRD quantifications, and use it to develop models for correcting the measured quartz concentrations of samples collected from the field. Seven nearly monodispersed pure quartz dusts, with mass median aerodynamic diameters (MMAD) ranging from 0.70 to 10.84 µm, were prepared by a liquid sedimentation device, and their unit XRD intensities (UI) were measured using the NIOSH Method 7500. The results show that UI increases (from 063 to 1.14) along with the rise in MMAD of the pure quartz dust. To examine the impact of the above results on quantifying field collected samples, both total dust and respirable dust samplings were conducted at seven different workplace environments. The results show that the quartz particles contained in all collected total dust samples (MMAD = 5.18-16.7 µm, GSD = 2.08-2.88) were coarser in their particle sizes than that of the reference quartz standard (NIST-SRM 1878; MMAD = 2.16 µm, GSD = 1.55), and the measured total quartz particle concentrations (C m ) were 16.6-22.5% lower than the corresponding true concentrations (C t ). However, for respirable dust samples (MMAD = 1.37-3.95 µm, GSD = 1.978-2.87), since collected quartz particle sizes could be either finer or coarser than that of the reference standard, both underestimation and overestimation were found in the present study (C m /C t = 0.881-1.09). To correct the measured concentrations of field collected samples, correcting models were developed based on the MMADs of the collected quartz particle samples and their corresponding UIs. This study yields correcting factors for the respirable fraction (CR f ) as CR f = 1.50 -0.67 × [1 -exp(-0.69 × MMAD)] (R 2 = 0.996, n = 7). However, the obtained CR f should be used with caution if the collected samples were found with quartz particle sizes falling outside the size range of the present study.