Targeted cytotoxic somatostatin analogue AN-238 inhibits somatostatin receptor-positive experimental colon cancers independently of their p53 status

Karoly Szepeshazi, Andrew V Schally, Gabor Halmos, Patricia Armatis, Francine Hebert, Baodong Sun, Anita Feil, Hippokratis Kiaris, Attila Nagy

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

The resistance of advanced colorectal cancers to therapy is often related to mutations in the p53 tumor suppressor gene. Because somatostatin (SRIF) receptors (ssts) are present in colorectal carcinomas, the treatment with targeted cytotoxic SRIF analogue AN-238, consisting of 2-pyrrolin-odoxorubicin (AN-201) linked to octapeptide SRIF carrier RC-121, may overcome this resistance by producing a higher concentration of the cytotoxic agent in the tumors. Four colon cancer cell lines, HCT-116 and LoVo expressing wild-type p53, and HCT-15 and HT-29 with mutated p53, were investigated. HCT-116, HCT-15, and HT-29, but not LoVo possess functional ssts. We analyzed changes in p53, p21, and proliferating cell nuclear antigen (PCNA) concentrations in these cells in vitro by immunoblotting after exposure to AN-238, its radical AN-201, or doxorubicin (DOX). Equitoxic doses of AN-238, AN-201, or DOX affected p53, p21, and PCNA differently. Analysis of the p21:p53 ratios revealed that DOX increased p53 levels, but most of p53 was mutated and inactive, whereas AN-238 produced smaller changes in p53 concentrations but enhanced its activity. In HCT-15 cells, PCNA:p21 ratios, which are indicators of proliferation and repair processes, remained unchanged after exposure to AN-238 but were increased by DOX. In vivo studies in nude mice demonstrated that AN-238, AN-201, and DOX were equally effective on HCT-116 tumors that express wild-type p53. However, AN-238 also inhibited the growth of HCT-15 and HT-29 cancers that express mutant p53, whereas AN-201 and DOX showed no effect. None of the compounds could suppress the proliferation of LoVo tumors that lack functional ssts. In conclusion, cytotoxic SRIF analogue AN-238 inhibits the growth of experimental colon cancers that express ssts, regardless of their p53 status.

Original languageEnglish
Pages (from-to)781-788
Number of pages8
JournalCancer Research
Volume62
Issue number3
StatePublished - Feb 1 2002
Externally publishedYes

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Somatostatin Receptors
Somatostatin
Colonic Neoplasms
Doxorubicin
Proliferating Cell Nuclear Antigen
Colorectal Neoplasms
Neoplasms
AN 238
Cytotoxins
Growth
Tumor Suppressor Genes
Immunoblotting
Nude Mice
AN 204
Cell Line
Mutation

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

Cite this

Targeted cytotoxic somatostatin analogue AN-238 inhibits somatostatin receptor-positive experimental colon cancers independently of their p53 status. / Szepeshazi, Karoly; Schally, Andrew V; Halmos, Gabor; Armatis, Patricia; Hebert, Francine; Sun, Baodong; Feil, Anita; Kiaris, Hippokratis; Nagy, Attila.

In: Cancer Research, Vol. 62, No. 3, 01.02.2002, p. 781-788.

Research output: Contribution to journalArticle

Szepeshazi, K, Schally, AV, Halmos, G, Armatis, P, Hebert, F, Sun, B, Feil, A, Kiaris, H & Nagy, A 2002, 'Targeted cytotoxic somatostatin analogue AN-238 inhibits somatostatin receptor-positive experimental colon cancers independently of their p53 status', Cancer Research, vol. 62, no. 3, pp. 781-788.
Szepeshazi, Karoly ; Schally, Andrew V ; Halmos, Gabor ; Armatis, Patricia ; Hebert, Francine ; Sun, Baodong ; Feil, Anita ; Kiaris, Hippokratis ; Nagy, Attila. / Targeted cytotoxic somatostatin analogue AN-238 inhibits somatostatin receptor-positive experimental colon cancers independently of their p53 status. In: Cancer Research. 2002 ; Vol. 62, No. 3. pp. 781-788.
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AU - Hebert, Francine

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