Interferon receptors and the caspase cascade regulate the antitumor effects of interferons on human pancreatic cancer cell lines

BACKGROUND: Interferons (IFNs) have antiproliferative effects on tumor cells. The apoptotic effects and sensitization to chemotherapy conferred by IFN therapy, however, are not clearly understood. The aims of the present study were to explore the apoptotic effects of IFNs in human pancreatic cancer cell lines and to attempt to define their ability to synergistically enhance sensitivity to 5-fluorouracil (5-FU) and gemcitabine, a mechanism that depends on the expression of IFN receptors. METHODS: Human pancreatic cancer cells were cultured alone or in combination with the chemotherapeutic agents 5-FU and gemcitabine. Differential dosages of IFN-alpha, -beta, and -gamma were also added to the cell lines concomitantly during a period of 24 to 96 hours. The cell line viability and effects of treatment were examined using the methylthiazol tetrazolium assay and single-stranded DNA apoptosis assay. The expression of IFN receptors was determined using immunohistochemistry. Caspase-8 inhibitor was used to block the caspase cascade. RESULTS: The antiproliferative and apoptotic effects of IFNs were most profoundly demonstrated on those cells that expressed the respective IFN receptor. The apoptotic effects provided by the interferons, however, were blocked by caspase-8 inhibition. The addition of IFNs significantly enhanced the cytotoxic effects of 5-FU and gemcitabine in those cell lines that expressed the corresponding IFN-alpha, -beta, or -gamma receptors. CONCLUSIONS: This study on pancreatic cancer cell lines has demonstrated that IFNs mediate apoptosis through IFN receptors and the caspase cascade. Enhanced cytotoxicity occurred when IFNs were combined with 5-FU and gemcitabine.     

Localization of the ABCG2 mitoxantrone resistance-associated protein in normal tissues

Reduced drug accumulation due to overexpression of individual members of the ATP binding cassette (ABC) superfamily of membrane transporters has been investigated as a cause of multidrug resistance and treatment failure in oncology. This study was designed to develop an immunohistochemical assay to determine the expression and localization of the 72kDa ABC half-transporter ABCG2 in normal tissues. Formalin-fixed, paraffin embedded archival tissue from 31 distinct normal tissues with an average of eight separate tissue samples of each were immunostained with rabbit-anti-ABCG2 antibody 405 using a modified avidin-biotin procedure. As a negative control, each sample was also stained with antibody pre-adsorbed with peptide to assess background staining. As a means of verification, selected tissues were also stained with the commercially available monoclonal antibody 5D3. ABCG2 positivity was consistently found in alveolar pneumocytes, sebaceous glands, transitional epithelium of bladder, interstitial cells of testes, prostate epithelium, endocervical cells of uterus, squamous epithelium of cervix, small and large intestinal mucosa/epithelial cells, islet and acinar cells of pancreas, zona reticularis layer of adrenal gland, kidney cortical tubules and hepatocytes. Placental syncytiotrophoblasts showed both cytoplasmic and surface staining. Our results support a hypothesis concluding that ABCG2 plays a role in the protection of organs from cytotoxins. However, many of the cell types expressing ABCG2 have a significant secretory function. These data suggest a dual function for ABCG2 in some tissues: the excretion of toxins and xenobiotics including anti-cancer agents and a potential, as-yet undefined role in the secretion of endogenous substrates.     

Management of salivary gland malignancies: current and developing therapies

Salivary gland tumors are rare, clinically diverse neoplasms that represent less than 1% of all malignancies. In locoregional recurrent or metastatic disease, systemic therapy is the standard approach. While numerous small phase II studies have evaluated the activity of cytotoxic agents, either alone or in combination, the response rates are generally modest with objective response rates ranging from 15%–50%. Duration of response is cited in the range of 6–9 months. Given this, further evaluation of novel therapies is mandatory in these diseases. With the emergence of molecular targeted therapy, these tumors become optimal candidates for trials of investigational drugs and established drugs for new indications. Of note, given the often indolent nature of disease, only patients with progressive disease should be enrolled and treated on these clinical trials. Study designs must incorporate stringent inclusion criteria to enable accurate reporting of disease response and stabilization. With dedication and co-operation, patients with these rare neoplasms can be accrued to clinical trials and the establishment of new treatment guidelines will be forthcoming.     

Cellular basis of induced alpha-fetoprotein synthesis by hepatocytes of adult mouse after hepatotoxic injury and partial hepatectomy.

The dynamics of α-fetoprotein (AFP) production by hepatocytes following different experimental manoeuvres that are known to induce regeneration of the liver was studied in young adult mice by simultaneous identification of dividing cells arrested during mitosis and of cells containing immuno-histochemically detectable AFP. After 70% hepatectomy AFP was produced by a few, largely periportally located hepatocytes, following waves of brisk and active cell division. Carbon tetrachloride (CCl₄)-induced hepatic injury, on the other hand, led to participation of a relatively larger number of cells in early AFP synthesis preceding a less extensive cell proliferation. Initially, AFP-producing cells were located in the peripheral part of the lobule but later they were more centrally placed, most often surrounding the zone of necrosis. Cells in mitosis often contained large amounts of AFP. CCl₄ administration 48 h after 70% hepatectomy resulted in extensive AFP production by approximately a quarter of all surviving liver cells, although the concurrent rate of cell division was low. Intoxication with dimethylnitrosamine showed a pattern identical to that of hepatectomy but both cell division and AFP production were of comparatively lower magnitude. It is concluded that at least two distinct modes exist for augmented synthesis of AFP by hepatocytes of adult animals. In one, pre-existent cells are stimulated to produce the protein before and irrespective of cell division while in the other, small amounts are synthesized by newly generated cells. Combination of the two mechanisms results in high levels of AFP production by stimulation of a large number of young hepatocytes.     

Human histocompatibility (HL-A) antigens in semen and their role in reproduction.

Seminal plasma from 7 of 10 normal persons was found to inhibit anti-HL-A2, 3, 7, 8, and 12 antisera specifically. Inhibition by seminal plasma appeared quantitatively less than that by whole serum and even less than that by platelets from the same individuals. No decrease in the number of offspring was found due to increased numbers of HL-A incompatibilities of the male spouse in 67 normal couples. No clear decrease in the number of pregnancies was observed in normal women with lymphocytotoxic antibodies. A similar study with infertile persons may yet reveal a role for HL-A antigens in human reproduction.     

Local anaesthetic activity of some new substituted acylamides II.

Six new substituted acylamides, chemically related to lignocaine were studied for local anaesthetic activity and toxicity in mice, frogs and guinea pigs. Only one of these compounds, w-pyrrolidino 2, 3, 5, 6 tetramethyl acetanilide was found to possess potency comparable to lignocaine with a slightly higher therapeutic index. Study of the S.A.R. of this group indicated that by removal of two methyl groups at position 3 and 5 in the above compound, a local anaesthetic with greater potency than lignocaine may be obtained. Further exploration of the potentialities of a compound having pyrrolidine group as a part of basic side chain is indicated.