The Comparative Effect of Morphine on Proliferation of Cancer Cell Lines Originating from Different Organs: An In Vitro Study

Abstract

Background/Objectives: Opium consumption was recently classified by the International Agency for Research on Cancer (IARC) monograph as carcinogenic to humans based on strong evidence for cancers of the larynx, lung, and urinary bladder, and limited evidence for cancers of the oesophagus, stomach, pancreas, and pharynx. This poses the question of a potential pro-cancer effect of pharmaceutical opioid analgesics. In vitro studies employing a variety of experimental conditions suggest that opioid alkaloids have proliferative or antiproliferative effects. We set out to reconcile this discrepancy and explore the hypothesis that opioids promote cancer cell proliferation in an organ-dependent fashion. Methods: Using strictly controlled conditions, we tested the effect of morphine on the proliferation of a series of human cancer cell lines isolated from organs where cancer risk was linked causally to opium consumption in human studies (i.e., lung, bladder, and larynx), or control organs where no link between cancer risk and opium consumption has been reported in human studies (i.e., breast, colon, prostate). Results: Our results showed a minimal effect on proliferation on any cell line and no trend supporting an organ-specific effect of morphine. Conclusions: This argues against a direct effect of opioids on tumour cell proliferation to support their organ-specific effect.

Keywords: cancer cell lines; morphine; proliferation.

Figure A1

Proliferation of lung cancer cell lines (A-549, H1299, H1975, and H460) in response to morphine. Cells were exposed to indicated concentrations of morphine or serum for 48 h. Resazurin reduction was quantified after 4, 6, and 8 h by fluorescence at an excitation of 560 nm and an emission of 590 nm. Results are expressed as a percentage of the viability of control cells unexposed to morphine or serum at time = 4 h. Data are shown as mean ± SEM, n = 3 independent experiments.

Figure A2

Proliferation of bladder cancer cell lines (HT-3376, T24, and UM-UC-3) in response to morphine. Cells were exposed to indicated concentrations of morphine or serum for 48 h. Resazurin reduction was quantified after 4, 6, and 8 h by fluorescence at an excitation of 560 nm and an emission of 590 nm. Results are expressed as a percentage of the viability of control cells unexposed to morphine or serum at time = 4 h. Data are shown as mean ± SEM, n = 3 independent experiments.

Figure A3

Proliferation of pancreas cancer cell lines (AsPC-1, BxPC-3, Capan-2, and MIA PaCa-2) in response to morphine. Cells were exposed to indicated concentrations of morphine or serum for 48 h. Resazurin reduction was quantified after 4, 6, and 8 h by fluorescence at an excitation of 560 nm and an emission of 590 nm. Results are expressed as a percentage of the viability of control cells unexposed to morphine or serum at time = 4 h. Data are shown as mean ± SEM, n = 3 independent experiments.

Figure A4

Proliferation of breast cancer cell lines (MCF-7, MDA-MB-231, and MDA-MB-468) in response to morphine. Cells were exposed to indicated concentrations of morphine or serum for 48 h. Resazurin reduction was quantified after 4, 6, and 8 h by fluorescence at an excitation of 560 nm and an emission of 590 nm. Results are expressed as a percentage of the viability of control cells unexposed to morphine or serum at time = 4 h. Data are shown as mean ± SEM, n = 3 independent experiments.

Figure A5

Proliferation of prostate cancer cell lines (22Rv1, DU145, and LNCaP) in response to morphine. Cells were exposed to indicated concentrations of morphine or serum for 48 h. Resazurin reduction was quantified after 4, 6, and 8 h by fluorescence at an excitation of 560 nm and an emission of 590 nm. Results are expressed as a percentage of the viability of control cells unexposed to morphine or serum at time = 4 h. Data are shown as mean ± SEM, n = 3 independent experiments.

Figure A6

Proliferation of colon cancer cell lines (Caco-2, HCT 116, and SW620) in response to morphine. Cells were exposed to indicated concentrations of morphine or serum for 48 h. Resazurin reduction was quantified after 4, 6, and 8 h by fluorescence at an excitation of 560 nm and an emission of 590 nm. Results are expressed as a percentage of the viability of control cells unexposed to morphine or serum at time = 4 h. Data are shown as mean ± SEM, n = 3 independent experiments.

Figure A7

Gene expression of mu (left), delta (centre), and kappa (right) opioid receptors expressed in transcripts per million (TPM), taken from the PCTA.

Figure 1

Proliferation of lung cancer cell lines (A-549, H1299, H1975, and H460) in response to morphine. Cells were exposed to indicated concentrations of morphine or serum for 48 h. Resazurin reduction was quantified after 4 h by fluorescence at an excitation of 560 nm and an emission of 590 nm. Results are expressed as a percentage of the viability of control cells unexposed to morphine or serum. Data are shown as mean ± SEM, n = 3 independent experiments. ns, not significant; *** p < 0.001; **** p < 0.0001.

Figure 2

Proliferation of bladder cancer cell lines (HT-1376, T24, and UM-UC-3) in response to morphine. Cells were exposed to indicated concentrations of morphine or serum for 48 h. Resazurin reduction was quantified after 4 h by fluorescence at an excitation of 560 nm and an emission of 590 nm. Results are expressed as a percentage of the viability of control cells unexposed to morphine or serum. Data are shown as mean ± SEM, n = 3 independent experiments. ns, not significant; *** p < 0.001; **** p < 0.0001.

Figure 3

Proliferation of pancreas cancer cell lines (AsPC-1, BxPC-3, Capan-2, and MIA PaCa-2) in response to morphine. Cells were exposed to indicated concentrations of morphine or serum for 48 h. Resazurin reduction was quantified after 4 h by fluorescence at an excitation of 560 nm and an emission of 590 nm. Results are expressed as a percentage of the viability of control cells unexposed to morphine or serum. Data are shown as mean ± SEM, n = 3 independent experiments. ns, not significant; * p < 0.05; ** p < 0.01; *** p < 0.001; **** p < 0.0001.

Figure 4

Proliferation of breast cancer cell lines (MCF-7, MDA-MB-231, and MDA-MB-468) in response to morphine. Cells were exposed to indicated concentrations of morphine or serum for 48 h. Resazurin reduction was quantified after 4 h by fluorescence at an excitation of 560 nm and an emission of 590 nm. Results are expressed as a percentage of the viability of control cells unexposed to morphine or serum. Data are shown as mean ± SEM, n = 3 independent experiments. ns, not significant; *** p < 0.001; **** p < 0.0001.

Figure 5

Proliferation of prostate cancer cell lines (22Rv1, DU145, and LNCaP) in response to morphine. Cells were exposed to indicated concentrations of morphine or serum for 48 h. Resazurin reduction was quantified after 4 h by fluorescence at an excitation of 560 nm and an emission of 590 nm. Results are expressed as a percentage of the viability of control cells unexposed to morphine or serum. Data are shown as mean ± SEM, n = 3 independent experiments. ns, not significant; * p < 0.05; ** p < 0.01; *** p < 0.001; **** p < 0.0001.

Figure 6

Proliferation of colon cancer cell lines (Caco-2, HCT 116, and SW620) in response to morphine. Cells were exposed to indicated concentrations of morphine or serum for 48 h. Resazurin reduction was quantified after 4 h by fluorescence at an excitation of 560 nm and an emission of 590 nm. Results are expressed as a percentage of the viability of control cells unexposed to morphine or serum. Data are shown as mean ± SEM, n = 3 independent experiments. ns, not significant; * p < 0.05; *** p < 0.001; **** p < 0.0001.