Induction of Premalignant and Malignant Changes in Nude Mice by Human Tumors-Derived Cell-Free Filtrates

Abstract

Carcinogenesis is a vast and heterogeneous, multi-step process driven by genetic and epigenetic operators leading to superimposed “tumor organs”. Based on our previous experiences of reproducing human donor’s histopathological hallmarks in healthy animals exposed to pathologic tissues homogenates, we examined the consequences of administering crude homogenates elaborated from invasive human tumors to nude mice. Subcutaneous administrations of increasing protein concentrations of breast carcinoma homogenates for 6 and 12 weeks, induced lungs atypical adenomatous hyperplasia, foci of lepidic and solid growth poorly-differentiated adenocarcinomas at the two time points. Non-atypical mucosal hyperplasia and adenomas were detected along the gastrointestinal tract. Another experiment addressed the impact of daily administrations (100 μg protein/mouse) of anaplastic sarcoma tissue homogenate for a month. This scheme triggered proliferative changes including: lung adenocarcinomas; a subcutaneous, poorly-differentiated mesenchymal cells tumor, a lymphoadenoma, and multiple gastrointestinal adenomas. When 50% of the month-treated animals were left to evolve treatment-free for other 35 days, a larger and broader incidence of neoplastic changes was found, suggesting autonomous growth: lung adenocarcinomas, a poorly differentiated thyroid tumor, an epithelial tumor within the periaortic brown adipose tissue, and multiple adenomas. These findings indicate that tumor crude homogenates contains soluble “transforming” messengers, that in a short period of time disrupt tissues’ proliferative and differentiation programs drifting to progressive neoplasms. This study expands previous evidences on the ability of human pathologic tissues-derived homogenates, to induce the reproduction of diseased donor’s histopathologic hallmarks.

Carcinogenic Effect of Human Tumors-Derived Cell Free-Filtrates in Nude Mice

“…Irrespective to its limitations, this study confirms, extends, and consequently supports our hypothesis that human malignant tissues-derived homogenates are able to disrupt the proliferative and differentiation programs of normal host cells, conducting to the onset of premalignant and malignant changes. A previous study from our group addressing the effects of 3 months administration of an invasive mammary carcinoma, and a pleomorphic sarcoma-derived CFFs, proved to act as a genuine carcinogen in nude mice, rendering epithelial and mesenchymal tumors that exhibited irreversible, metastasizing, and autonomous progression [25]. The findings obtained in the present study while administering the breast carcinoma-derived CFF to mice, faithfully reproduce and converge with these previous pathologic descriptions [25].…”

“…A previous study from our group addressing the effects of 3 months administration of an invasive mammary carcinoma, and a pleomorphic sarcoma-derived CFFs, proved to act as a genuine carcinogen in nude mice, rendering epithelial and mesenchymal tumors that exhibited irreversible, metastasizing, and autonomous progression [25]. The findings obtained in the present study while administering the breast carcinoma-derived CFF to mice, faithfully reproduce and converge with these previous pathologic descriptions [25]. We deem this is a meaningful event given that the multidimensional complexity of cancer has historically derived in variability, heterogeneity, and lack of reproducibility in basic research experiments [33].…”

“…The experimental methodology used in this opportunity was as previously described [25], so that tumors-derived CFFs were prepared using sterile physiologic saline solution with no purification processes, or any other type of chemical manipulation. These homogenates represent a pure extract of the pathologic tissues, a rich-in-content material, and a vehicle of donor cells' soluble signatures that have previously proved to recapitulate in healthy recipient rodents, histopathologic hallmarks of diabetic angiopathy and neuropathy, and non-diabetic related arteriosclerosis as models of non-communicable chronic diseases [23,24].…”

“…Mice in protocol I received 100µg of protein (as arbitrary unit) of normal skin tissue or breast malignant samples, whereas for protocols II and III protein concentration was reduced to 50µgall in a volume of 250µL of normal saline, once a day, from Monday through Saturday for 12 weeks. We assumed this administration time window for the three protocols since it proved to induce malignant tissue changes in a previous study [25]. Subcutaneous and intraperitoneal routes were alternatively used on weekly bases to prevent local injury due to repeated trauma.…”

“…Subsequently and following the hypothesis that CFFs may contain cell-transforming messengers, we examined the consequences on nude mice of administering the homogenates of surgically excised malignant tumors. Tumors-derived crude material induced premalignant and malignant changes in different organs, and in a narrow temporary window [25].…”