Telomerase enzyme activity as a diagnostic tool to distinguish effusions of malignant and benign origin

Total protein concentration as a predictor of in neoplastic peritoneal and pleural effusions of dogs

BACKGROUND

The diagnosis of neoplastic cavitary effusions requires the identification of neoplastic cells in effusions, yet the cytologic appearance of neoplastic effusions can be highly variable due to the varied mechanisms of formation. Additional parameters might aid in the interpretation of equivocal cytologic results.

OBJECTIVES

Our goal was to evaluate whether total protein concentrations can be used to support the diagnosis of neoplasia in the peritoneal and pleural effusions of dogs with lower cellularities (≤5000 nucleated cells/μL).

METHODS

Pleural and peritoneal fluid analyses from dogs presented to the University of Illinois Veterinary Teaching Hospital between 2014 and 2019 were evaluated retrospectively. Effusions were categorized as neoplastic or non-neoplastic based on histology or cytology. Non-neoplastic effusions were subcategorized according to mechanism: decreased oncotic pressure, increased hydrostatic pressure, increased vascular permeability, leakage of urine, and leakage of lymph. The TP and blood albumin to fluid TP ratio (Alb_blood :TP_fluid ) were compared among groups.

RESULTS

Twenty-seven neoplastic and 65 non-neoplastic cases were evaluated. TP was higher in the neoplastic group (P = .001) than in the non-neoplastic group. Neoplastic effusions had a lower Alb_blood :TP_fluid than non-neoplastic (P = .001), and effusions with Alb_blood :TP_fluid of ≤0.6 were 5.6 times more likely to be neoplastic (95% CI 1.69-17.36; P = .003).

CONCLUSIONS

Fluid TP concentrations were significantly greater in neoplastic than non-neoplastic effusions; however, given the considerable overlap between groups, the diagnostic utility of this difference is low. A neoplastic etiology might be more likely in cases with an Alb_blood :TP_fluid ≤0.6.

Telomere length and telomerase activity in canine mammary gland tumors

OBJECTIVE

To measure telomere length and telomerase activity in naturally occurring canine mammary gland tumors.

SAMPLE POPULATION

27 mammary gland tumor specimens obtained during resection or necropsy and 12 mammary gland tissue specimens obtained from healthy (control) dogs.

PROCEDURE

Telomere length in tissue specimens was measured by use of restriction endonuclease digestion and Southern blot analysis. Telomerase activity was measured by use of a telomeric repeat amplification protocol assay.

RESULTS

Telomere length in mammary gland tumors ranged from 11.0 to 21.6 kilobase pairs (kbp; mean +/- SEM, 14.5+/-0.5 kbp) but did not differ among tumor types. Telomeres in mammary gland tumors were slightly shorter than in normal tissue specimens, but telomere length could not be directly compared between groups, because mean age of dogs was significantly different between groups. Age was negatively correlated with telomere length in control dogs but was not significantly correlated with length in affected dogs. Telomerase activity was detected in 26 of 27 mammary gland tumors and in 4 of 12 normal tissue specimens. However, telomerase activity and telomere length were not correlated in tumor specimens.

CONCLUSIONS AND CLINICAL RELEVANCE

Telomere length is maintained in canine mammary gland tumors regardless of the age of the affected dog. Measurement of telomere length may be a useful tool for monitoring the in vivo effects of telomerase inhibitors in dogs with tumors.

Telomerase activity in clinically normal dogs and dogs with malignant lymphoma

OBJECTIVES

To determine whether telomerase activity was present in lymph nodes, buffy coat, and serum samples from dogs with malignant lymphoma (ML) and in liver, lymph node, buffy coat, and serum samples from clinically normal dogs

SAMPLE POPULATION

Tissue specimens and blood samples were obtained from 11 clinically normal adult dogs (age range, 1 to 4 years) and 14 client-owned dogs with ML.

PROCEDURE

The telomere repeat amplification protocol assay was used to quantify telomerase activity in the tissues from clinically normal dogs and dogs with ML.

RESULTS

Of 11 clinically normal dogs, 8 had lymph node samples, 5 had liver samples, and 1 had buffy coat samples with detectable telomerase activity. None of the serum samples from the clinically normal dogs had detectable telomerase activity. Of 14 dogs with ML, 9 had lymph node samples, 3 had buffy coat samples, and 1 had serum samples with measurable telomerase activity.

CONCLUSIONS AND CLINICAL RELEVANCE

Telomerase activity was not specific to tumor cells and overlapped with that found in cells from clinically normal dogs. Telomerase activity in neoplastic lymph nodes was not substantially different from that found in lymph nodes from clinically normal dogs. The determination of telomerase activity cannot be used as a sole diagnostic test for cancer. Therapeutic modalities directed toward the telomerase enzyme may not be feasible in dogs, because somatic tissues from clinically normal dogs possess variable amounts of telomerase activity.