## 3 Results
### H1299 Cell Nucleus Shapes and Sizes Change in Response to MMW Irradiation  
To examine whether the observed effects were transient (reversible) or irreversible (stable), the nuclei sizes and shapes were monitored over 7-14 days after irradiation. MMW irradiation for 2, 4, and/or 10 min duration led to changes in nuclear size in irradiated groups (Figure 3A,B). Samples irradiated for 2 min showed a relative 100% increase in the nuclear sizes of cells from subgroups 6-7 (cell division active) only as compared to untreated (sham) cells (Table 2). Under the 2 min regime, cells from the other subgroups were not so dramatically affected. By delivering higher energy dosage more prominent effects on nuclear sizes were seen under the 4 and 10 min exposure regimes. MMW irradiation were seen to elicit two major responses in the treated cells indicative of apoptosis and senescence respectively as previously reported [19]. One group of cells (from subgroups 1-4) mostly reduced their nuclear sizes (by 25-200%) while another set (from subgroups 4-10) increased their nuclear sizes (by 30-300%) (Figure 3B and Table 2) under the 4 and 10 min exposure regimes, respectively. The cells irradiated for 10 min did not survive after a few days in culture, demonstrating that the effects of the treatment were irreversible on cell viability. Thus, experimental observations for further investigations were possible only on the groups that were treated with shorter durations of irradiation. The changes observed on cell and nuclear morphology associated with shorter and longer exposure durations; this clearly confirm the strong and specific effect of MMW on lung cancer cell properties and viability. This experiment also demonstrates that the cells from subgroups 6-7 (cell division active) were the ones most affected indicating the effectiveness of MMW treatment in inhibiting metastasis. Under the short-term observation period (Day 1, 90 min following irradiation) the effects resulting from 2 min of irradiation were less profound as compared to 4 and 10 min exposures. The 4 min irradiation regime delivering a higher dose of energy showed that the major effect of MMW treatment was reduction in nuclear size distribution in response to the irradiation reminiscent of accelerated apoptosis [19] and mortality. However, the small population of the large cells with multi-lobular nuclei increased their sizes 3-fold as compared to control. This may indicate that nuclei lose their ability to maintain their shape and/or that new subgroups of cells with different properties appear and transition into pro-apoptosis. Further, over 14 days of experimental observation, nuclei morphology prominently changed in response to the irradiation. The irradiated cells that contained only one nucleus were changed from oval to kidney-like for both 2- and 4-min exposure times (Figure 3A), likely due to changes in DNA condensation via adverse regulation and the appearance of small pro-apoptotic subgroups in the cell populations. These results demonstrate that W-band (75-105 GHz) MMW has an effect on cell sizes as well as the cell nuclei in a dose dependent manner. _Appl. Sci._**2020**, _10_, 4813  
**Figure 3. The distribution of the nuclei sizes and shapes in control and treated H1299 cells populations in response to MMW irradiation. (A) Representative images of nuclei morphology after irradiation. (a) Control cells nuclei show circle or oval morphology; (b) cells with enlarged nuclear morphology under the 2 min irradiation regime corresponding to subgroups 1–2 from Table 2 observed over long-term incubation of 7–14 days after MMW treatment; (c) and (e) cells with altered nuclear morphology under the 4 min irradiation regime observed on the day of experiment (Day 1); and (d) and (f) cells with enlarged nuclear morphology under the 4 min irradiation regime corresponding to subgroups 4–10 from Table 2 observed over long-term incubation of 7–14 days after MMW treatment. Arrows indicate altered nuclei as compared to control.