Lack of Effects of Viral Sialoadenitis and Depletion of Epidermal Growth Factor on Initiation of Hepatic Carcinogenesis in the Rat

Abstract

Sialodacryoadenitis (SDA) is a commonly-encountered coronaviral infection in laboratory rats that causes acute destruction of submandibular salivary glands. SDA results in depletion of salivary epidermal growth factor (EGF) and may thereby affect EGF-dependent cell growth processes. The purpose of this study was to determine the effects of SDA virus (SDAV) infection on the growth factor-dependent stages of experimental liver carcinogenesis. Rats were injected ip with the carcinogen diethylnitrosamine (DENA) at 1, 2, or 3 weeks following inoculation with SDAV. Uninfected control rats were treated only with DENA. The salivary glands of SDAV-inoculated and control rats were stained using the immunoperoxidase method for the detection of EGF. Residual submandibular salivary gland lesions and focal depletion of EGF were still evident in affected submandibular glands for up to 42 days after SDAV infection. Serum EGF concentrations measured at 9, 28, and 42 days following SDAV inoculation were reduced, but were not significantly different in comparison with non-inoculated, DENA-treated control rats. Initiated hepatocytes were detected 21 days after DENA treatment in formalin-fixed sections by an immunoperoxidase stain for the P isoenzyme of the enzyme glutathione S-transferase (GST-P). There was no significant difference in the number of foci of GST-P positive cells in a comparison of initiated cells in SDAV-inoculated and non-inoculated rats. Based on this model, concurrent infection with SDAV does not appear to have any significant effects on the initial stages of chemical hepatocarcinogenesis in the rat.

Keywords

Diethylnitrosamine epidermal growth factor glutathione S-transferase immunoperoxidase sialodacryoadenitis virus submandibular salivary gland

References

1. Barka T (1980). Biologically active polypeptides in submandibular glands. J. Histochem. Cytochem. 28: 836–859.

2. Bucher NLR , Patel U , and Cohen S (1978). Hormonal factors and liver growth. Adv. Enzyme Regul. 16: 205–213.

3. Carthew P and Slinger RP (1981). Diagnosis of Sialodacryoadenitis virus infection of rats in a virulent enzootic outbreak. Lab. Anim. 15: 339–342.

4. Collins MJ (1986). Prevalence of pathogenic viruses and mycoplasmas which are currently a problem to research. In: Complications of Viral and Mycoplasmal Infections in Rodents to Toxicology Research and Testing, TE Hamm (ed). Hemisphere Publishing Corp., New York, pp. 1–9.

5. Doi K , Yasoshima A , Kojima A , Okawa H , Kurabe S , and Okaniwa A (1980). Pathological observations on natural cases of sialodacryoadenitis virus of rats. Exp. Anim. 29: 419–426.

6. Eisenbrandt DL , Hubbard GB , and Schmidt RE (1982). A subclinical epizootic of sialodacryoadenitis in rats. Lab. Anim. Sci. 32: 655–659.

7. Farber E and Sarma DSR (1987). Hepatocarcinogenesis: A dynamic cellular perspective. Lab. Invest. 56: 4–22.

8. Gresik EW , Van Der Noen H , and Barka T (1979). Epidermal growth factor-like material in rat submandibular gland. Am. J. Anat. 156: 83–89.

9. Hickman RL (1986). Toxicology: Complications caused by murine viruses and mycoplasmas. In: Viral and Mycoplasmal Infections of Laboratory Rodents: Effects on Biomedical Research, PN Bhatt , RO Jacoby , HC Morse , and AE New (eds). Academic Press, London, pp. 693–720.

10.

10. Jonas AM , Craft J , Black CL , Bhatt PN , and Hilding D (1969). Sialodacryoadenitis in the rat: A light and electron microscopic study. Arch. Path. Pathol. Lab. Med. 88: 613–622.

11.

11. Kurachi H , Okamoto S , and Oka T (1985). Evidence for the involvement of the submandibular gland epidermal growth factor in mouse tumorigenesis. Proc. Natl. Acad. Sci. USA 82: 5940–5943.

12.

12. Lussier G and Descoteaux J-P (1986). Prevalence of natural virus infections in laboratory mice and rats used in Canada. Lab. Anim. Sci. 36: 145–148.

13.

13. Moore MA and Kitagawa T (1986). Hepatocarcino-genesis in the rat: The effect of promoters and carcinogens in vivo and in vitro. Int. Rev. Cytol. 101: 125–173.

14.

14. Moore MA , Nakagawa K , Satoh K , Ishikawa T , and Sato K (1987). Single GST-P positive liver cells-putative initiated hepatocytes. Carcinogenesis 8: 483–486.

15.

15. Murphy RA , Watson AY , Metz J , and Forssmann WG (1980). The mouse submandibular gland: An exocrine organ for growth factors. J. Histochem. Cy-tochem. 28: 1329–1331.

16.

16. Percy DH , Hayes MA , Kocal TE , and Wojcinski ZW (1988). Depletion of salivary gland epidermal growth factor by sialodacryoadenitis infection in the Wistar rat. Vet. Pathol. 25: 183–192.

17.

17. Pitot HC and Sirica AE (1980). The stages of initiation and promotion in hepatocarcinogenesis. Bio-chem. Biophys. Acta 605: 191–215.

18.

18. Richman RA , Claus TH , Pilkis SJ , and Friedman DL (1976). Hormonal stimulation of DNA synthesis in primary cultures of adult rat hepatocytes. Proc. Natl. Acad. Sci. USA 73: 3589–3593.

19.

19. Rushmore TH , Harris L , Nagai M , Sharma RN , Hayes MA , Cameron R , Murray RK , and Farber E (1988). Purification and characterization of P-52 (gluta-thione s-transferase-p or 7–7) from normal liver and putative preneoplastic liver nodules. Cancer Res. 48: 2805–2812.

20.

20. Sato K , Kitahara A , Satoh K , Ishikawa T , Tatematsu M , and Ito N (1984). The placental form of glutathione s-transferase as a new marker protein for preneoplasia in rat chemical hepatocarcinogenesis. Jpn. J. Cancer Res. 75: 199–202.

21.

21. Satoh K , Kitahara A , Soma Y , Inaba Y , Hatayama I , and Sato K (1985). Purification, induction, and distribution of placental glutathione transferase: A new marker enzyme for preneoplastic cells in the rat chemical hepatocarcinogenesis. Proc. Natl. Acad. Sci. USA 82: 3964–3968.

22.

22. Schaudies RP and Savage CR (1986). Isolation of rat epidermal growth factor (r-EGF): Chemical, biological and immunological comparisons with mouse and human EGF. Comp. Biochem. Physiol. [B] 84: 497–505.

23.

23. Schultz GS , White M , Mitchell R , Brown G , Lynch J , Twardzik DR , and Todaro GJ (1987). Epithelial wound healing enhanced by transforming growth fac-tor-α and vaccinia growth factor. Science 235: 350–352.

24.

24. Smith AL (1983). An immunofluorescent test for detection of serum antibody to rat coronaviruses. Lab. Anim. Sci. 33: 157–160.

25.

25. Sporn MB , Roberts AB , Smith JM , Ward JM , and Sodek J (1983). Polypeptide transforming growth factors isolated from bovine sources and used for wound healing in vivo. Science 219: 1329–1331.

26.

26. Taketani Y and Oka T (1983). Epidermal growth factor stimulates cell proliferation of mouse mammary epithelial cells in culture. Endocrinology 113: 871–877.

27.

27. Taketani Y and Oka T (1983). Possible physiological role of epidermal growth factor in the development of mouse mammary gland during pregnancy. FEBS Let. 152: 256–260.

28.

28. Tsuda H , Lee G , and Farber E (1980). Induction of resistant hepatocytes as a new principle for a possible short-term in vivo test for carcinogenesis. Cancer Res. 40: 1157–1164.

29.

29. Tsutsumi O , Tsutsumi A , and Oka T (1987). Importance of epidermal growth factor in implantation and growth of mouse mammary tumour in female nude mice. Cancer Res. 47: 4651–4653.

30.

30. Utsumi K , Ishikawa T , and Maeda T (1980). Infectious sialadenitis and rat breeding. Lab. Anim. 14: 303–307.

31.

31. Williams GM (1980). The pathogenesis of rat liver cancer caused by chemical carcinogens. Biochem. Biophys. Acta 605: 167–189.

32.

32. Wollenberg GK , Harris L , Farber E , and Hayes MA (1989). Inverse relationship between epidermal growth factor induced proliferation and expression of high affinity surface epidermal growth factor receptors in rat hepatocytes. Lab. Invest. 60: 254–259.

33.

33. Wright NA , Pike C , and Elia G (1990). Induction of a novel epidermal growth factor-secreting cell lineage by mucosal ulceration in human gastrointestinal cells. Nature 343: 82–85.

34.

34. Ying TS , Sarma DSR , and Farber E (1981). Role of acute hepatic necrosis in the induction of early steps in liver carcinogenesis by diethylnitrosamine. Cancer Res. 41: 2096–2102.