Human T-cell leukemia virus type I (HTLV-I) is recognized as the etiologic agent of adult T-cell leukemia (ATL), a disease endemic in certain regions of southeastern Japan, Africa, and the Caribbean basin. Although HTLV-I can immortalize T lymphocytes in culture, factors leading to tumor progression after HTLV-I infection remain elusive. Previous attempts to propagate the ATL tumor cells in animals have been unsuccessful. Severe combined immunodeficient (SCID) mice have previously been used to support the survival of human lymphoid cell populations when inoculated with human peripheral blood lymphocytes (PBL). SCID mice were injected intraperitoneally with PBL from patients diagnosed with ATL, HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP), or from asymptomatic HTLV-I-seropositive patients. Many of these mice become persistently infected with HTLV-I. Furthermore, after human reconstitution was established in these mice, HTLV-I-infected cells displayed a proliferative advantage over uninfected human cells. Lymphoblastic lymphomas of human origin developed in animals injected with PBL from two ATL patients. The tumor cells represented outgrowth of the original ATL leukemic clone in that they had monoclonal or oligoclonal integrations of the HTLV-I provirus identical to the leukemic clone and predominantly expressed the cell surface markers, CD4 and CD25. In contrast, cell lines derived by HTLV immortalization of T cells in vitro did not persist or form tumors when inoculated into SCID mice, indicating differences between in vitro immortalized cells and ATL leukemic cells. This system represents the first small animal model to study HTLV-I tumorigenesis in vivo.

The effect of fendiline on cytosolic free Ca2+ concentrations ([Ca2+]i) and proliferation has not been explored in human oral cancer cells. This study examined whether fendiline altered Ca2+ levels and caused cell death in OC2 human oral cancer cells. [Ca2+]i and cell viability were measured using the fluorescent dyes fura-2 and WST-1, respectively. Fendiline at concentrations above 10 μM increased [Ca2+]i in a concentration-dependent manner. The Ca2+ signal was reduced partly by removing extracellular Ca2+. The fendiline-induced Ca2+ influx was sensitive to blockade of L-type Ca2+ channel blockers. In Ca2+-free medium, after pretreatment with 50 μM fendiline, 1 μM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor)-induced [Ca2+]i rises were inhibited; and conversely, thapsigargin pretreatment nearly abolished fendiline-induced [Ca2+]i rises. Inhibition of phospholipase C with 2 μM U73122 did not change fendiline-induced [Ca2+]i rises. At concentrations between 5 and 25 μM, fendiline killed cells in a concentration-dependent manner. The cytotoxic effect of 15 μM fendiline was not reversed by prechelating cytosolic Ca2+ with BAPTA/AM. Collectively, in OC2 cells, fendiline induced [Ca2+]i rises by causing Ca2+ release from the endoplasmic reticulum and Ca2+ influx from L-type Ca2+ channels. Furthermore, fendiline-caused cytotoxicity was not via a preceding [Ca2+]i rise.

In this study, we took advantage of the overexpression of human epidermal growth factor receptor 2 (HER-2) in prostate cancers to design lentiviruses with modified envelope proteins that bind antibodies to specific cell-surface antigens. When bound to trastuzumab (Herceptin, Genentech, CA), lentiviruses were able to selectively infect androgen-sensitive LNCaP and castrationresistant C4-2 human prostate cancer cell lines, both of which express high levels of HER-2. To test for a therapeutic effect, we engineered our antibody-binding lentiviruses to express thymidine kinase, which can convert the non-toxic pro-drug ganciclovir (GCV) into a cytotoxic form. LNCaP and C4-2 cells infected by these viruses were sensitive to GCV killing. In vivo, C4-2 xenograft tumors treated either intratumorally or i.v. with trastuzumab-bound lentivirus expressed luciferase, although the latter route was less tumor specific. When a prostate-specific promoter for governing luciferase expression was combined with trastuzumab-mediated delivery, there was a further enrichment in targeting viral gene expression in prostate tumors. In conclusion, we found that although prostate cancers that express high levels of HER-2 are resistant to the killing effects of trastuzumab, they can be targeted for selective gene expression and destruction by viruses with envelope proteins engineered to bind this antibody.

A man from Chile developed an aggressive mature T cell leukemia associated with marked eosinophilia. The neoplastic lymphocytes were of T helper surface phenotype, and they expressed the p24 and p19 antigens of human T cell leukemia virus (HTLV). A cell line (ME) was established from the patient's peripheral blood cells that was initially composed of eosinophils and T and B lymphocytes. The B lymphocytes of the cell line are polyclonal and contain Epstein-Barr virus (EBV) DNA. Many of the T lymphocytes, a few of the B lymphocytes, and none of the eosinophils express HTLV p19 and p24 antigens. By 6 months of culture, the ME line no longer contained eosinophils. A variant line of ME was established; this variant (ME-2) is notable because the cells (greater than 80%) adhere tightly to the bottom of the culture flask; they do not express T lymphocyte markers, but 30% of the cells contain cytoplasmic mu heavy immunoglobulin chains. These pre-B and null lymphocytes contain p19 and p24 antigens (80% of cells), have the HTLV- I genome, and are able to transform normal T lymphocytes in vitro. We isolated a B lymphocyte clone (11A) from ME that expresses cytoplasmic immunoglobulin (70% of cells) and p19 and p24 antigens (75% of cells), contains the EBV and HTLV genomes, and can transform T lymphocytes from normal volunteers. These data show that B lymphocytes can be infected with HTLV, although no disease of HTLV-infected B lymphocytes has been reported. The T lymphocytes from normal adult peripheral blood were easily immortalized (about 70% efficiency) by cocultivation with lethally irradiated ME cells. Twenty-five of 27 of the transformant lines were composed of T lymphocytes with helper antigens, and two of the lines were of T suppressor antigen phenotype. All the cell lines that were tested constitutively produce lymphokines, including colony- stimulating factor (CSF), erythroid-potentiating activity (EPA), macrophage migration-inhibitory factory (MIF), neutrophil-inhibitory factor (NIF), and differentiation-inducing factor (DIF).

A man from Chile developed an aggressive mature T cell leukemia associated with marked eosinophilia. The neoplastic lymphocytes were of T helper surface phenotype, and they expressed the p24 and p19 antigens of human T cell leukemia virus (HTLV). A cell line (ME) was established from the patient's peripheral blood cells that was initially composed of eosinophils and T and B lymphocytes. The B lymphocytes of the cell line are polyclonal and contain Epstein-Barr virus (EBV) DNA. Many of the T lymphocytes, a few of the B lymphocytes, and none of the eosinophils express HTLV p19 and p24 antigens. By 6 months of culture, the ME line no longer contained eosinophils. A variant line of ME was established; this variant (ME-2) is notable because the cells (greater than 80%) adhere tightly to the bottom of the culture flask; they do not express T lymphocyte markers, but 30% of the cells contain cytoplasmic mu heavy immunoglobulin chains. These pre-B and null lymphocytes contain p19 and p24 antigens (80% of cells), have the HTLV- I genome, and are able to transform normal T lymphocytes in vitro. We isolated a B lymphocyte clone (11A) from ME that expresses cytoplasmic immunoglobulin (70% of cells) and p19 and p24 antigens (75% of cells), contains the EBV and HTLV genomes, and can transform T lymphocytes from normal volunteers. These data show that B lymphocytes can be infected with HTLV, although no disease of HTLV-infected B lymphocytes has been reported. The T lymphocytes from normal adult peripheral blood were easily immortalized (about 70% efficiency) by cocultivation with lethally irradiated ME cells. Twenty-five of 27 of the transformant lines were composed of T lymphocytes with helper antigens, and two of the lines were of T suppressor antigen phenotype. All the cell lines that were tested constitutively produce lymphokines, including colony- stimulating factor (CSF), erythroid-potentiating activity (EPA), macrophage migration-inhibitory factory (MIF), neutrophil-inhibitory factor (NIF), and differentiation-inducing factor (DIF).