Philip J. Bergman

Prognostic Factors in Dogs with Urinary Bladder Carcinoma

Medical records and biopsy specimens were retrospectively reviewed from 25 dogs diagnosed with unresectable urinary bladder carcinoma and treated with chemotherapy. Our intention was to identify clinical, histologic, and immunohistochemical indicators of prognosis. Immunohistochemical stains for P-glycoprotein, glutathione-S-transferase pi, and factor VIII-related antigen were applied to archived tissue. There were more spayed female dogs than castrated male dogs (76% versus 24%). Transitional cell carcinoma was the most common tumor (88%, n = 22), followed by undifferentiated carcinoma (8%, n = 2) and squamous cell carcinoma (4%, n = 1). Overall median survival was 251 days. Histologic diagnosis and immunohistochemical characteristics did not correlate with prognosis. Spayed females survived significantly longer than castrated males (358 days versus 145 days, P = .042). Dogs that received either doxorubicin or mitoxantrone in addition to a platinum-based chemotherapeutic (either cisplatin or carboplatin) lived significantly longer than those that received only a platinum compound (358 days versus 132 days, P = .042).

Canine Hepatic Neuroendocrine Carcinoma: An Immunohistochemical and Electron Microscopic Study

Ten dogs with neuroendocrine carcinoma of the liver were selected for inclusion in the study. Clinical signs were anorexia (7), vomiting (5), polydipsia/polyuria (3), icterus (2), lethargy (2), weight loss (2), paresis (1), ataxia (1), weakness (1), collapse (1), and urinary tract infection (1). Hematologic and biochemical abnormalities included anemia (2/8), leukocytosis (4/8), high liver enzyme activity (serum alkaline phosphatase, 7/9; alanine transaminase, 7/9; aspartate transaminase, 8/9), and high total bilirubin (6/9). Grossly, the tumors were diffuse, involving all liver lobes in six dogs, and two dogs had various-sized nodules in addition to diffuse involvement. Histologically, there were eight tumors with solid or trabecular pattern (group A), one tumor with cords or rows of neoplastic cells (group B), and one tumor with multiple rosette-like structures (group C). immunohistochemical studies revealed that all 10 neoplasms were positive for at least one of the endocrine markers used: neuron-specific enolase (NSE; 8/10), synaptophysin (5/10), and chromogranin-A (3/10). A panel of NSE, chromagranin-A, and synaptophysin detected 100% of the tumors in our series. Electron microscopy confirmed the diagnosis by the presence of intracytoplasmic neurosecretory granules in the two examined cases. our results show that neuroendocrine markers commonly used in humans can be used for the diagnosis of hepatic neuroendocrine carcinoma in dogs, preferably a panel of synaptophysin, chromagranin-A, and NSE because chromogranin-A alone is not as useful in dogs as in humans.

Radioresistance, chemoresistance, and apoptosis resistance. The past, present, and future.

A wide variety of cancer therapy resistance mechanisms are available, with perhaps surprising overlap between causes of chemotherapy and radiation resistance. As previously discussed, most of the widely used chemotherapeutic agents and gamma-radiation utilize apoptosis as the common death pathway, thereby making apoptosis and the ability to manipulate apoptosis of integral importance to the future of cancer therapy. This is evidenced by the information explosion on this topic in the last 5 years. Obviously much remains to be learned. However, with the aforementioned cooperation of the oncology team and a greater understanding of the molecular mechanisms behind cancer and cancer therapy resistance, response rates, survival times, the quality of life of patients enduring antineoplastic therapies, and the importance of comparative oncology can only increase. We look forward to the findings in the coming years on this incredibly clinically relevant topic with great fondness and uncertainty.

Immunohistochemical detection of HER‐2/neu expression in spontaneous feline mammary tumours

Mammary gland tumours (MGT) are the third most common tumours in the cat. At least 85% are malignant and metastasis is common. The HER-2/neu protooncogene encodes a 185-kDa transmembrane tyrosine receptor kinase protein. Approximately 25-30% of human MGT demonstrate HER-2/neu protein overexpression in the malignant cells, and overexpression has been associated with an increased metastatic propensity and a decreased prognosis. No reports have been published, to date, investigating the expression of Her-2/neu in cats or cats with spontaneous mammary tumours. Based on the increased percentage of malignant mammary cancers in cats, compared to that in dogs, and the correlation of an increased malignancy and a decreased prognosis with Her-2 overexpression in human mammary cancer, we hypothesized that cats with spontaneous malignant mammary adenocarcinoma overexpress Her-2/neu in the neoplastic mammary epithelial cells. Thirty cats with MGT were assayed for Her-2/neu immunohistochemical expression. The median percentage of cells from feline MGT expressing Her-2/neu by utilizing the Dako polyclonal and CB11 monoclonal antibodies was 85 and 92.5, respectively. Her-2/neu expression intensity grades 2 and 3 consistent with the overexpression by utilizing the Dako polyclonal and CB11 monoclonal antibodies were observed in 90 and 76.7% of cats with MGT, respectively. The level of overexpression concordance across the two antibodies was 70%. The results from this study suggest that Her-2/neu overexpression is common in cats with spontaneous MGT, and therefore appears to represent an excellent model for Her-2/neu-overexpressing human breast cancer.

Radiation Therapy Toxicities

Since the infancy of radiology and radiation therapy, reactions to radiation have been noted and followed, and attempts have been made to minimize these reactions. We have turned to radiobiologists to explain these reactions and to radiation oncologists to prevent or decrease the normal tissue effects of radiation therapy. Radiation toxicities are divided into early (acute) and late (chronic) reactions; however, it is important to note that severe toxicities are rare and occur typically in less than 5% of veterinary radiation therapy patients.

An N-myristoylated protein kinase C-α pseudosubstrate peptide that functions as a multidrug resistance reversal agent in human breast cancer cells is not a P-glycoprotein substrate

Abstractu2003Protein kinase C-α (PKC-α) activation is an important contributing factor in human breast cancer MCF-7 MDR cell drug resistance. We recently reported the use of N-myristoylated PKC-α pseudosubstrate peptides with potent PKC-α inhibitory activity as reversal agents of drug resistance in MCF-7 MDR cells. The peptides potently inhibit phosphorylation of the PKC-α substrates P-glycoprotein (P-gp), raf kinase and PKC-α itself in MCF-7 MDR cells in association with a severalfold induction of intracellular uptake of P-gp substrate chemotherapeutics and a statistically significant twofold increase in cellular chemosensitivity. We now report that the N-myristoylated PKC-α pseudosubstrate peptide N-myristoyl-RFARKGALRQKNV (P3) is not a P-gp substrate in MCF-7 MDR cells based on a comparison of the cellular uptake of [125I]-radiolabeled P3 in MCF-7 MDR vs MCF-7 WT cells. The extent of cellular uptake of the radiolabeled peptide in the drug-resistant cell line MCF-7 MDR was either greater than or equivalent to the uptake in the parental drug-sensitive MCF-7 WT cell line over a time course of 30 min to 6 h, and across a peptide concentration range of 25u200a–u200a100 μM. Additionally, treatment of the MCF-7 MDR cells with verapamil (VPL), a known P-gp efflux inhibitor, had no effect on the cellular accumulation of radiolabeled P3. Our results provide direct evidence that the N-myristoylated pseudosubstrate peptide is taken up equivalently by drug-sensitive and MDR cancer cells and therefore has potential value as an MDR reversal agent that operates by a novel mechanism.

Potent induction of human colon cancer cell uptake of chemotherapeutic drugs by N-myristoylated protein kinase C-α (PKC-α) pseudosubstrate peptides through a P-glycoprotein-independent mechanism

Phorbol ester protein kinase C (PKC) activators and PKC isozyme over-expression have been shown to significantly reduce intracellular accumulation of chemotherapeutic drugs, in association with the induction of multidrug resistance (MDR) in drug-sensitive cancer cells and enhancement of drug resistance in MDR cancer cells. These observations constitute solid evidence that PKC plays a significant role in the MDR phenotype of cancer cells. PKC-catalyzed phosphorylation of the drug-efflux pump P-glycoprotein was recently ruled out as a contributing factor in MDR. At present, the sole drug transport-related event that has been identified as a component of the role of PKC in MDR is PKC-induced expression of the P-glycoprotein-encoding gene mdr1. The objective of this study was to test the hypothesis that PKC can modulate the uptake of chemotherapeutic drugs in cancer cells independently of P-glycoprotein. We analyzed the effects of selective PKC activators/inhibitors on the uptake of radiolabelled cytotoxic drugs by cultured human colon cancer cells that lacked P-glycoprotein activity and did not express the drug efflux pump at the level of message (mdr1) or protein. We found that the selective PKC activator 12-O-tetradecanoylphorbol-13-acetate (TPA) significantly reduced uptake of [14C] Adriamycin and [3H] vincristine in human colon cancer cells devoid of P-glycoprotein activity, and that PKC-inhibitory N-myristoylated PKC-α pseudosubstrate synthetic peptides potently and selectively induced uptake of the cytotoxic drugs in the phorbol ester-treated and non-treated colon cancer cells. TPA treatment of the cells did not induce expression of either P-glycoprotein or its message mdr1. In contrast with [14C]Adriamycin and [3H] vincristine uptake, [3H] 5-fluorouracil uptake by the cells was unaffected by TPA and reduced by the PKC-inhibitory peptides. These results indicate that PKC activation can significantly reduce the uptake of multiple cytotoxic drugs by cancer cells independently of P-glycoprotein, and that N-myristoylated PKC-α pseudosubstrate peptides potently and selectively induce uptake of multiple cytotoxic drugs in cultured human colon cancer cells by a novel mechanism that does not involve P-glycoprotein and may involve PKC isozyme inhibition. Thus, N-myristoylated PKC-α pseudosubstrate peptides may offer a basis for the development of agents that reverse intrinsic drug resistance in human colon cancer.

Characterization of spindle cell component of ferret (Mustela putorius furo) adrenal cortical neoplasms – correlation to clinical parameters and prognosis

Adrenal cortical epithelial tumours are common in ferrets. A variant tumour type with prominent spindle cell proliferation has been identified. We characterized these variant tumours with light microscopy and immunohistochemical analysis and correlate these features to clinical parameters and prognosis. We classified 24 ferret adrenal cortical masses with recognizable spindle cell proliferation obtained from the AMC and AFIP databases, based on percentage of spindle cells present and features of malignancy. These masses were separated into hyperplastic nodules and adenomas (both with 1-24% spindle cells), mixed adenomas (>or=25% spindle cells), adenocarcinomas (1-24%) and mixed adenocarcinomas (>or=25% spindle cells). Tumours were evaluated immunohistochemically for smooth muscle actin (SMA) and estrogen receptor (ER) expression. Disease-free interval (DFI) and survival time (ST) were calculated using Kaplan-Meier product limit method. Of 24 cases of spindle cell variant adrenal tumours, one was a hyperplastic nodule, 10 were adenomas, three were mixed adenomas, six were adenocarcinomas and four were mixed adenocarcinomas. The proliferative spindle cell cytoplasm was SMA-positive (smooth muscle myocyte origin). ER positivity, seen in nine of 24 cases, was restricted to adenocarcinomas, mixed adenomas and mixed adenocarcinomas. DFI and ST were significantly reduced in mixed adenocarcinomas or tumours with ER expression. DFI was significantly reduced in tumours with marked smooth muscle. The spindle cell component of these variant adrenal tumours is smooth muscle in origin. The presence of abundant smooth muscle, a more malignant histologic grade (mixed adenocarcinomas) and ER expression are significantly positively correlated to both decreased DFI and decreased ST.

Radiation Oncology of Head and Neck Tumors

Malignant tumors of the head and neck region occur commonly in veterinary medicine. Unfortunately, tumors in the head and neck can cause treatment dilemmas because many neoplastic entities at this site are locally aggressive. Additional local therapies such as radiation therapy are becoming commonplace as standardized therapies for many head and neck tumors in veterinary medicine.